On the Implant Communication and MAC Protocols for a WBAN

On the Implant Communication and MAC Protocols for a WBAN Abstract Recent advances in micro-electro-mechanical systems (MEMS), wireless communication, low-power intelligent sensors, and semiconductor technologies have allowed the realization of a wireless body area network (WBAN). A WBAN provides unobtrusive health monitoring for a long period of time with real-time updates to the physician. It is widely used for ubiquitous healthcare, entertainment, and military applications. The implantable and wearable medical devices have several critical requirements such as power consumption, data rate, size, and low-power medium access control (MAC) protocols. This article consists of two parts: body implant communication, which is concerned with the communication to and from a human body using RF technology, and WBAN MAC protocols, which presents several low-power MAC protocols for a WBAN with useful guidelines. In body implant communication, the in-body radio frequency (RF) performance is affected considerably by the implants depth inside the human body as well as by the muscle and fat. We observe best performance at a depth of 3cm and not close to the human skin. Furthermore, the study of low-power MAC protocols highlights the most important aspects of developing a single, a low-power, and a reliable MAC protocol for a WBAN. Keywords: In-body, on-body, RF communication, Implant, WBAN 1. Introduction Cardiovascular diseases are the foremost cause of deaths in the United States and Europe since 1900. More than ten million people are affected in Europe, one million in the US, and twenty two million people in the world [1]. The number is projected to be triple by 2020, resulting in an expenditure of around 20% of the gross domestic product (GDP). The ratio is 17% in South Korea and 39% in the UK [2]. The healthcare expenditure in the US is expected to be increased from $2.9 trillion in 2009 to $4 trillion US dollars in 2015 [3]. The impending health crisis attracts researchers, industrialists, and economists towards optimal and quick health solutions. The non-intrusive and ambulatory health monitoring of patients vital signs with real time updates of medical records via internet provide economical solutions to the health care systems. A wireless body area network (WBAN) is becoming increasingly important for healthcare systems, sporting activities, and members of emergency as well as military services. WBAN is an integration of in-body (implants) and on-body (wearable) sensors that allow inexpensive, unobtrusive, and long-term health monitoring of a patient during normal daily activities for prolonged periods of time. In-body radio frequency (RF) communications have the potential to dramatically change the future of healthcare. For example, they allow an implanted pacemaker to regularly transmit performance data and the patients health status to the physician. However, the human body poses many wireless transmission challenges. This is partially conductive and consists of materials having different dielectric constants and characteristics impedance. The interface of muscles and fats may reflect the RF wave rather than transmitting it. The key elements of an RF-linked implant are the in-body antenna and the communi cation link performance. Also, in the case of many implants and wearable sensors, a low-power MAC protocol is required to accommodate the heterogeneous traffic in a power-efficient manner. This article is divided into two parts: body implant communication and WBAN MAC protocols. In the body implant communication part, we look at the RF communication link performance at various depths inside a human (artificial) body. In the MAC part, we review the existing low-power MAC protocols and discuss their pros and cons in the context of a WBAN. We further provide alternative MAC solutions for in-body and on-body communication systems. The rest of the article is divided into three sections. In section 2, we present a discussion on body implant communication including in-body electromagnetic induction, RF communication, antenna design, and the communication link performance. Section 3 discusses several low-power MAC protocols and realizes a need for a new, a low-power, and a reliable MAC protocol for a WBAN. The final section concludes our work. 2. Body Implant Communication There are several ways to communicate with an implant that includes the use of electromagnetic induction and RF technology. Both are wireless and their use depends on the application requirements. Further, the key elements of an RF-linked implant are the in-body antenna and the communication link performance. The following part discusses in-body electromagnetic induction, RF communication, antenna design, and the communication link performance. 2.1. In-body Electromagnetic Induction Several applications still use electromagnetic coupling to provide a communication link to an implant device. In this scheme, an external coil is held very close to the body that couples to a coil implanted just below the skin surface. The implant is powered by the coupled magnetic field and requires no battery for communication. Data is transferred from the implant by altering the impedance of the implanted loop that is detected by the external coil and electronics. This type of communication is commonly used to identify animals that have been injected with an electronic tag. Electromagnetic induction is used when continuous, long-term communication is required. The base band for electromagnetic communication is typically 13.56 MHz or 28 MHz, with other frequencies also available. The choice of a particular band is subject to regulation for maximum specific absorption rate (SAR). The inductive coupling achieves best power transfer efficiency when uses large transmit and receive coil s. It, however, becomes less efficient when the space is an issue of the device is implanted deep inside the human body. Furthermore, inductive coupling technique does not support a very high data rate and cannot initiate a communication session from inside of the body. 2.2. In-body RF Communication Compared with the electromagnetic induction, RF communication dramatically increases bandwidth and supports a two-way data communication. The band designated for the in-body RF communication is medical implant communication service (MICS) band and is around 403 to 405 MHz. This band has a power limit of 25  µW in the air and is usually split into ten channels of 300 kHz bandwidth each. The human body is a medium that poses numerous wireless transmission challenges. It consists of various components that are not predictable and will change as the patient ages, gains or losses weight, or even changes posture. Values of dielectric constant (ÃŽ µr), conductivity (ÏÆ') and characteristic impedance (Zo) for some body tissue are given in table 1 [4]. This demonstrates that these two tissue types are very different. Also, the dielectric constant affects the wavelength of a signal. At 403 MHz, the wavelength in the air is 744mm, but in muscle with ÃŽ µr = 50 the wavelength reduces to 105mm, which helps in designing implanted antennas. 2.3. In-body Antenna Design A modern in-body antenna should be tuneable by using an intelligent transceiver and software routine. This enables the antenna coupling circuit to be optimised. Due to the frequency, and available volume, a non-resonant antenna is commonly used. It has a lower gain than a resonant antenna. This makes design of the antenna coupling circuit very important. Antenna options are dictated by the location of the implant. A patch antenna can be used when the implant is flat. Patch antennas are comprised of a flat insulating substrate coated on both sides with a conductor. The substrate is a body compatible material with a platinum or a platinum/iridium conductor. The upper surface is the active face and is connected to the transceiver. The connection to the transceiver needs to pass through the case where the hermetic seal is maintained, requiring a feed-through. The feed-through must have no filter capacitors present; these are common on other devices. An implanted patch antenna is electrically larger than its physical size because it is immersed in a high (ÃŽ µr) medium. It can be much larger electrically if the substrate is of higher (ÃŽ µr), such as titania or zirconia. A loop antenna can also be attached to the implant. This antenna operates mostly by the magnetic field, whereas the patch operates mostly by the electric field. The loop antenna delivers performance comparable to that of a dipole, but with a considerably smaller size. In addition, the magnetic permeability of muscle or fat is very similar to that of an air, unlike the dielectric constant that varies considerably. This property enables an antenna to be built and used with much less need for retuning. A loop antenna can be mounted on the case in a biocompatible structure. 2.4. In-body Link Performance The demonstration system consists of a base-station, an implant, antennas, and a controlling laptop. The base-station contains a printed circuit board (PCB) with a wakeup RF circuit, a Zarlink ZL70101 IC, and a micro-controller. It sends a wakeup signal on industrial, scientific, and medical (ISM) 2.4 GHz band to power up the implant to communicate. It also supports communication within the MICS band. The implant contains a Zarlink ZL70101 IC, a micro-controller, and a battery. The power limits of the wakeup signal for ISM and MICS bands transmitters are 100mW and 25  µW respectively. Experiments that measure the performance of an implant inside a living body are difficult to arrange. The alternative is to use 3D simulation software or a body phantom defined in [5]. The use of 3D simulation software is time consuming and hence practically not valuable. Therefore, measurements are generally performed using the body phantom and immersing a battery-powered implant into it [6]. Since no additional cables are attached to the test implant, the interference errors in the measurements are minimal. The body phantom is filled with a liquid that mimics the electrical properties of the human body tissues. The test environment is an anechoic chamber that includes a screened room. The interior walls of the room have sound-absorbent cones to minimize any reflections from walls or the floor that could distort the results. In real life, however, the results will be affected by the reflections from walls, desks, and other equipment and hardware. The body phantom is mounted on a woo den stand (non-conductive). The distance from the body phantom to the base-station is 3m. The MICS base-station dipole antenna is mounted on a stand. 1(a) shows the anechoic chamber with a body phantom (on the wooden stand), a log periodic test antenna (foreground), and a base-station dipole (right). The log periodic antenna is used to calculate the power radiated from the body phantom. A depth is defined as the horizontal distance between the outer skin of the phantom and the test implant. Vertical polarization of the implant is the case when the long side of the box and the patch antenna is vertical. The link performance is measured once the communication link is established. The measurements include the effective radiated power (ERP) from the implant, the received signal at the implant from the base-station, and the link quality. Measurements are made over a set distance with all the combinations of implant and test antenna polarisations, i.e., vertical-vertical (V-V), horizontal-vertical (H-V), vertical-horizontal (V-H), and horizontal-horizontal (H-H) polarisations. Typical results are shown in 1(b) where the ERP is calculated from the received signal power and the antenna characteristics. The measurement of the signal levels is done with the log periodic antenna and the spectrum analyzer. It can be seen in the that there is a significant difference in signal levels with polarisation combinations and depths. For a V-V polarisation, the ERP increases from a 1cm depth to a maximum between 2 and 7 cm, and then it decreases. The gradual increase is due to the simulated body acti ng as a parasitic antenna. The also shows how the signal level is affected by the depth with different polarisation. Such a test needs to be done with the antenna that is to be used in the final product. To measure the received signal at the implant, the Zarlink ZL70101 has an inbuilt receive signal strength indication (RSSI) function that gives a measure of the signal level detected. RSSI is a relative measurement with no calibration. The implant receives and measures a continuous wave signal transmitted by the base-station. In this case, the implant and the base-station antennas are vertically polarised. 1(c) shows an increase in the signal level at a depth between 3 and 4cm for a 15dec power. The power settings refer to the base-station and are cond to set the ERP to 25  µW. Signal levels are not valuable unless they are related to data transmission. One way to maintain the link quality is to measure the number of times the error correction is invoked during the transmission of 100 blocks of data. Two types of error correction codes, i.e., error correction code (ECC) and cyclic redundancy code (CRC) are invoked to maintain data integrity and reliability. The fewer ECC and CRC invocations result in better link quality. In 1(d), the error correction is lowest at a depth between 3 and 5 cm. A sample of ECC data collected at a 3cm implant depth is given in Table 2. The Count indicates the number of data blocks, the Time (ms) indicates the block transmission time, and the ECC indicates the number of times it is invoked. During the transmission of 100 blocks of data at a 3cm depth, the ECC is invoked 368 times, which is further equivalent to an average 3.68 times (as given in 1(d)). 2.5. Discussion The ERP, RSSI, as well as the ECC and CRC plots show that the implant demonstrates the best performance at a depth between 3 and 5 cm. The depth and position of an implant is not chosen for engineering performance but for the best clinical reasons. The implant designer must be aware of the possible losses through the human body. The attenuation and the parasitic antenna effects vary from patient to patient, with the position of the implant and with the time as the patient gains, or looses weight. Therefore, these factors need to be built into the link budget. 3. WBAN MAC Protocols Some of the common objectives in a WBAN are to achieve maximum throughput, minimum delay, and to maximize the network lifetime by controlling the main sources of energy waste, i.e., collision, idle listening, overhearing, and control packet overhead. A collision occurs when more than one packet transmits data at the same time. The collided packets have to be retransmitted, which consumes extra energy. The second source of energy waste is idle listening, meaning that a node listens to an idle channel to receive data. The third source is overhearing, i.e., to receive packets that are destined to other nodes. The last source is control packet overhead, meaning that control information area added to the payload. Minimal number of control packets should be used for data transmission. Generally MAC protocols are grouped into contention-based and schedule-based MAC protocols. In contention-based MAC protocols such as carrier sense multiple access/collision avoidance (CSMA/CA) protocols, nodes contend for the channel to transmit data. If the channel is busy, the node defers its transmission until it becomes idle. These protocols are scalable with no strict time synchronization constraint. However, they incur significant protocol overhead. In schedule-based protocols such as time division multiple access (TDMA) protocols, the channel is divided into time slots of fixed or variable duration. These slots are assigned to nodes and each node transmits during its slot period. These protocols are energy conserving protocols. Since the duty cycle of radio is reduced, there is no contention, idle listening and overhearing problems. But these protocols require frequent synchronization. Table 3 compares CSMA/CA and TDMA protocols. 3.1. WBAN MAC Requirements The most important attribute of a good MAC protocol for a WBAN is energy efficiency. In some applications, the device should support a battery life of months or years without interventions, while others may require a battery life of tens of hours due to the nature of the applications. For example, cardiac defibrillators and pacemakers should have a lifetime of more than 5 years, while swallowable camera pills have a lifetime of 12 hours. Power-efficient and flexible duty cycling techniques are required to minimize the idle listening, overhearing, packet collisions and control packet overhead. Furthermore, low duty cycle nodes should not receive frequent synchronization and control information (beacon frames) if they have no data to send or receive. The WBAN MAC should also support simultaneous operation on in-body (MICS) and on-body channels (ISM or UWB) at the same time. In other words, it should support multiple physical layer (Multi-PHYs) communication or MAC transparency. Other important factors are scalability and adaptability to changes in the network, delay, throughput, and bandwidth utilization. Changes in the network topology, the position of the human body, and the node density should be handled rapidly and successfully. The MAC protocol for a WBAN should consider the electrical properties of the human body and the diverse traffic nature of in-body and on-body nodes. For example, the data rate of in-body nodes varies, ranging from few kbps in pacemaker to several Mbps in capsular endoscope. In the following sections, we discuss proposed MAC protocols for a WBAN with useful guidelines. We also present a case study of IEEE 802.15.4, PB-TDMA, and S-MAC protocols for a WBAN using NS2 simulator. 3.2. Proposed MAC Protocols for a WBAN In this section, we study proposed MAC protocols for a WBAN followed by useful suggestions/comments. Many of the proposed MAC protocols are the extension of existing MAC protocols originally proposed for wireless sensor networks (WSNs). 3.2.1. IEEE 802.15.4 IEEE 802.15.4 has remained the main focus of many researchers during the past few years. Some of the main reasons of selecting IEEE 802.15.4 for a WBAN were low-power communication and support of low data rate WBAN applications. Nicolas et.al investigated the performance of a non-beacon IEEE 802.15.4 in [7], where low upload/download rates (mostly per hour) are considered. They concluded that the non-beacon IEEE 802.15.4 results in 10 to 15 years sensor lifetime for low data rate and asymmetric WBAN traffic. However, their work considers data transmission on the basis of periodic intervals which is not a perfect scenario in a real WBAN. Furthermore, the data rate of in-body and on-body nodes are not always low, i.e., it ranges from 10 Kbps to 10 Mbps, and hence reduces the lifetime of the sensor nodes. Li et.al studied the behavior of slotted and unslotted CSMA/CA mechanisms and concluded that the unslotted mechanism performs better than the slotted one in terms of throughput and lat ency but with high cost of power consumption [8]. Intel Corporation conducted a series of experiments to analyze the performance of IEEE 802.15.4 for a WBAN [9]. They deployed a number of Intel Mote 2 [10] nodes on chest, waist, and the right ankle. Table 4 shows the throughput at a 0dBm transmit power when a person is standing and sitting on a chair. The connection between ankle and waist cannot be established, even for a short distance of 1.5m. All other connections show favourable performance. Dave et al. studied the energy efficiency and QoS performance of IEEE 802.15.4 and IEEE 802.11e [11] MAC protocols under two generic applications: a wave-form real time stream and a real-time parameter measurement stream [12]. Table 5 shows the throughput and the Power (in mW) for both applications. The AC_BE and AC_VO represent the access categories voice and best-effort in the IEEE 802.11e. Since the IEEE 802.15.4 operates in the 2.4 GHz unlicensed band, the possibilities of interference from other devices such as IEEE 802.11 and microwave are inevitable. A series of experiments to evaluate the impact of IEEE 802.11 and microwave ovens on the IEEE 802.15.4 transmission are carried out in [13]. The authors considered XBee 802.15.4 development kit that has two XBee modules. Table 6 shows the affects of microwave oven on the XBee remote module. When the microwave oven is ON, the packet success rate and the standard deviation is degraded to 96.85% and 3.22% respectively. However, there is no loss when the XBee modules are taken 2 meters away from the microwave oven. 3.2.2. Heartbeat Driven MAC Protocol (H-MAC) A Heartbeat Driven MAC protocol (H-MAC) [14] is a TDMA-based protocol originally proposed for a star topology WBAN. The energy efficiency is improved by exploiting heartbeat rhythm information in order to synchronize the nodes. The nodes do not need to receive periodic information to perform synchronization. The heartbeat rhythm can be extracted from the sensory data and hence all the rhythms represented by peak sequences are naturally synchronized. The H-MAC protocol assigns dedicated time slots to each node to guarantee collision-free transmission. In addition, this protocol is supported by an active synchronization recovery scheme where two resynchronization schemes are implemented. Although H-MAC protocol reduces the extra energy cost required for synchronization, it does not support sporadic events. Since the TDMA slots are dedicated and not traffic adaptive, H-MAC protocol encounters low spectral/bandwidth efficiency in case of a low traffic. For example, a blood pressure node may not need a dedicated time slot while an endoscope pill may require a number of dedicated time slots when deployed in a WBAN. But the slots should be released when the endoscope pill is expelled. The heartbeat rhythm information varies depending on the patient condition. It may not reveal valid information for synchronization all the time. One of the solutions is to assign the time slots based on the nodes traffic information and to receive synchronization packets when required, i.e., when a node has data to transmit/receive. 3.2.3. Reservation-based Dynamic TDMA Protocol (DTDMA) A Reservation-based Dynamic TDMA Protocol (DTDMA) [15] is originally proposed for a normal (periodic) WBAN traffic where slots are allocated to the nodes which have buffered packets and are released to other nodes when the data transmission/reception is completed. The channel is bounded by superframe structures. Each superframe consists of a beacon used to carry control information including slot allocation information, a CFP period a configurable period used for data transmission, a CAP period a fixed period used for short command packets using slotted aloha protocol, and a configurable inactive period used to save energy. Unlike a beacon-enabled IEEE 802.15.4 superframe structure where the CAP duration is followed by CFP duration, in DTDMA protocol the CFP duration is followed by CAP duration in order to enable the nodes to send CFP traffic earlier than CAP traffic. In addition, the duration of inactive period is configurable based on the CFP slot duration. If there is no CFP t raffic, the inactive period will be increased. The DTDMA superframe structure is given in 2(a). It has been shown that for a normal (periodic) traffic, the DTDMA protocol provides more dependability in terms of low packet dropping rate and low energy consumption when compared with IEEE 802.15.4. However, it does not support emergency and on-demand traffic. Although the slot allocation based on the traffic information is a good approach, the DTDMA protocol has several limitations when considered for the MICS band. The MICS band has ten channels where each channel has 300 Kbps bandwidth. The DTDMA protocol is valid only for one channel and cannot operate on ten channels simultaneously. In addition, the DTDMA protocol does not support the channel allocation mechanism in the MICS band. This protocol can be further investigated for the MICS band by integrating the channel information in the beacon frame. The new concept may be called Frequency-based DTDMA (F-DTDMA), i.e., the coordinator first selects one of the channels in the MICS band and then divides the selected channel in TDMA superframe (s) according to the DTDMA protocol. However the FCC has imposed several restrictions on the channel selection/allocation mechanism in the MICS band, which further creates problems for the MAC designers. 3.2.4. BodyMAC Protocol A BodyMAC protocol is a TDMA-based protocol where the channel is bounded by TDMA superframe structures with downlink and uplink subframes as given in 2(b) [16]. The downlink frame is used to accommodate the on-demand traffic and the uplink frame is used to accommodate the normal traffic. There is no proper mechanism to handle the emergency traffic. The uplink frame is further divided into CAP and CFP periods. The CAP period is used to transmit small size MAC packets. The CFP period is used to transmit the normal data in a TDMA slot. The duration of the downlink and uplink superframes are defined by the coordinator. The advantage of the BodyMAC protocol is that it accommodates the on-demand traffic using the downlink subframe. However, in case of low-power implants (which should not receive beacons periodically), the coordinator has to wake up the implant first and then send synchronization packets. After synchronization, the coordinator can request/send data in the downlink subframe. The wake up procedure for low-power implants is not defined in the BodyMAC protocol. One of the solutions is to use a wakeup radio in order to wake up low-power implants before using the downlink subframe. In addition the wakeup packets can be used to carry control information such as channel (MICS band) and slot allocation information from the coordinator to the nodes. Finally, the BodyMAC protocol uses the CSMA/CA protocol in the CAP period which is not reliable for a WBAN. This should be replaced by slotted-ALOHA as done in DTDMA. Further details on low-power MAC protocols (originally proposed for WSNs) for a WBAN are given in Appendix I. 3.3. Case Study: IEEE 802.15.4, PB-TDMA, and SMAC Protocols for a WBAN In this section, we investigate the performance of a beacon-enabled IEEE 802.15.4, preamble-based TDMA [17], and SMAC protocols for an on-body communication system. Our analysis is verified by extensive simulations using NS-2. The wireless physical parameters are considered according to a low-power Nordic nRF2401 transceiver (Chipcon CC2420 radio [18] is considered in case of IEEE 802.15.4) [19]. This radio transceiver operates in the 2.4-2.5 GHz band with an optimum transmission power of -5dBm. We use the shadowing propagation model throughout the simulations. We consider a total of 7 nodes firmly placed on a human body. The nodes are connected to the coordinator in a star topology. The distribution of the nodes and the coordinator is given in 3(a). The initial nodes energy is 5 Joules. The packet size is 120 bytes. The average data transmission rate of ECG, EEG, and EMG is 10, 70, and 100 kbps. The transport agent is a user datagram protocol (UDP). Since the traffic is an uplink t raffic, the buffer size at the coordinator is considered unlimited. In a real WBAN, the buffer size should be configurable based on the application requirements. For energy calculation, we use the existing energy model defined in NS-2. The simulation area is 33 meter and each node generates constant bit rate (CBR) traffic. The CBR traffic is an ideal model for some of the medical applications, where the nodes send data based on pre-defined traffic patterns. However, most of the nodes in a WBAN have heterogeneous traffic characteristics and they generate periodic and aperiodic traffic. In this case, they will have many traffic models operating at the same time, ranging from CBR to variable bit rate (VBR). 3(b) shows the throughput of the IEEE 802.15.4, PB-TDMA, and S-MAC protocols. The performance of the IEEE 802.15.4, when cond in a beacon-enabled mode, outperforms PB-TDMA and S-MAC protocols. The efficiency of a MAC protocol depends on the traffic pattern. In this case, S-MAC protocol results poor performance because the traffic scenario that we generated is not an ideal scenario for the S-MAC. 3(c) shows the residual energy at various nodes during simulation time. When nodes finish their transmission, they go into sleep mode, as indicated by the horizontal line. The coordinator has a considerable energy loss because it always listens to the other nodes. However, the energy consumption of the coordinator is not a critical issue in a WBAN. We further analyze the residual energy at the ECG node for different transmission powers. There is a minor change in energy loss for three different transmission powers as given in 3(d). This concludes that reducing the transmission power only d oes not save energy unless supported by an efficient power management scheme. The IEEE 802.15.4 can be considered for certain on-body medical applications, but it does not achieve the level of power required for in-body nodes. It is not sufficient for high data rate medical and non-medical applications due to its limitations to 250 kbps. Furthermore, it uses slotted or unslotted CSMA/CA where the nodes are required to sense the channel before transmission. However, the channel sensing is not guaranteed in MICS band because the path loss inside the human body due to tissue heating is much higher than in free space. Bin et.al studied the clear channel assessment (CCA) range of in-body nodes which is only 0.5 meters [20]. This unreliability in CCA indicates that CSMA/CA is not an ideal technique for the in-body communication system. An alternative approach is to use a TDMA-based protocol that contains a beacon, a configurable contention access period (CCAP), and a contention free period (CFP) [21]. Unlike the IEEE 802.15.4, this protocol is required to use a slot ted-ALOHA protocol in the CCAP instead of CSMA/CA. The CCAP period should contain few slots (3 or 4) of equal duration and can be used for short data transmission and a guaranteed time slot (GTS) allocation. To enable a logical connection between the in-body and the on-body communication systems, a method called bridging function can be used as discussed in [21]. The bridging function can integrate in-body and on-body nodes into a WBAN, thus satisfying the MAC transparency requirement. Further details about bridging function are given in [22]. 3.4. Discussion Since the CSMA/CA is not suitable due to unreliable CCA and heavy collision problems, it can be seen that the most reliable power-efficient protocol is a TDMA-based protocol. Many protocols have been proposed for a WBAN and most of them are based on a TDMA-based mechanism. However, all of them have pros and cons for a real WBAN system that should operate on Multi-PHYs (MICS, ISM, and UWB) simultaneously. The MAC transparency has been a hot topic for the MAC designers since different bands have different characteristics in terms of data rate, number of channels in a particular frequency band, and data prioritization. A good MAC protocol should enable reliable operation on MICS, ISM, and UWB etc bands simultaneously. The main problems are related to MICS band due to FCC restrictions [23]. According to FCC, â€Å"Within 5 seconds prior to initiating a communications session, circuitry associated with a medical implant programmer/control transmitter must monitor the channel or channels the MICS system devices intend to occupy for a minimum of 10 milliseconds per channel.† In other words, the coordinator must perform Listen-before-talking (LBT) criteria prior to a MICS communication sessions. The implants are not allowed to On the Implant Communication and MAC Protocols for a WBAN On the Implant Communication and MAC Protocols for a WBAN Abstract Recent advances in micro-electro-mechanical systems (MEMS), wireless communication, low-power intelligent sensors, and semiconductor technologies have allowed the realization of a wireless body area network (WBAN). A WBAN provides unobtrusive health monitoring for a long period of time with real-time updates to the physician. It is widely used for ubiquitous healthcare, entertainment, and military applications. The implantable and wearable medical devices have several critical requirements such as power consumption, data rate, size, and low-power medium access control (MAC) protocols. This article consists of two parts: body implant communication, which is concerned with the communication to and from a human body using RF technology, and WBAN MAC protocols, which presents several low-power MAC protocols for a WBAN with useful guidelines. In body implant communication, the in-body radio frequency (RF) performance is affected considerably by the implants depth inside the human body as well as by the muscle and fat. We observe best performance at a depth of 3cm and not close to the human skin. Furthermore, the study of low-power MAC protocols highlights the most important aspects of developing a single, a low-power, and a reliable MAC protocol for a WBAN. Keywords: In-body, on-body, RF communication, Implant, WBAN 1. Introduction Cardiovascular diseases are the foremost cause of deaths in the United States and Europe since 1900. More than ten million people are affected in Europe, one million in the US, and twenty two million people in the world [1]. The number is projected to be triple by 2020, resulting in an expenditure of around 20% of the gross domestic product (GDP). The ratio is 17% in South Korea and 39% in the UK [2]. The healthcare expenditure in the US is expected to be increased from $2.9 trillion in 2009 to $4 trillion US dollars in 2015 [3]. The impending health crisis attracts researchers, industrialists, and economists towards optimal and quick health solutions. The non-intrusive and ambulatory health monitoring of patients vital signs with real time updates of medical records via internet provide economical solutions to the health care systems. A wireless body area network (WBAN) is becoming increasingly important for healthcare systems, sporting activities, and members of emergency as well as military services. WBAN is an integration of in-body (implants) and on-body (wearable) sensors that allow inexpensive, unobtrusive, and long-term health monitoring of a patient during normal daily activities for prolonged periods of time. In-body radio frequency (RF) communications have the potential to dramatically change the future of healthcare. For example, they allow an implanted pacemaker to regularly transmit performance data and the patients health status to the physician. However, the human body poses many wireless transmission challenges. This is partially conductive and consists of materials having different dielectric constants and characteristics impedance. The interface of muscles and fats may reflect the RF wave rather than transmitting it. The key elements of an RF-linked implant are the in-body antenna and the communi cation link performance. Also, in the case of many implants and wearable sensors, a low-power MAC protocol is required to accommodate the heterogeneous traffic in a power-efficient manner. This article is divided into two parts: body implant communication and WBAN MAC protocols. In the body implant communication part, we look at the RF communication link performance at various depths inside a human (artificial) body. In the MAC part, we review the existing low-power MAC protocols and discuss their pros and cons in the context of a WBAN. We further provide alternative MAC solutions for in-body and on-body communication systems. The rest of the article is divided into three sections. In section 2, we present a discussion on body implant communication including in-body electromagnetic induction, RF communication, antenna design, and the communication link performance. Section 3 discusses several low-power MAC protocols and realizes a need for a new, a low-power, and a reliable MAC protocol for a WBAN. The final section concludes our work. 2. Body Implant Communication There are several ways to communicate with an implant that includes the use of electromagnetic induction and RF technology. Both are wireless and their use depends on the application requirements. Further, the key elements of an RF-linked implant are the in-body antenna and the communication link performance. The following part discusses in-body electromagnetic induction, RF communication, antenna design, and the communication link performance. 2.1. In-body Electromagnetic Induction Several applications still use electromagnetic coupling to provide a communication link to an implant device. In this scheme, an external coil is held very close to the body that couples to a coil implanted just below the skin surface. The implant is powered by the coupled magnetic field and requires no battery for communication. Data is transferred from the implant by altering the impedance of the implanted loop that is detected by the external coil and electronics. This type of communication is commonly used to identify animals that have been injected with an electronic tag. Electromagnetic induction is used when continuous, long-term communication is required. The base band for electromagnetic communication is typically 13.56 MHz or 28 MHz, with other frequencies also available. The choice of a particular band is subject to regulation for maximum specific absorption rate (SAR). The inductive coupling achieves best power transfer efficiency when uses large transmit and receive coil s. It, however, becomes less efficient when the space is an issue of the device is implanted deep inside the human body. Furthermore, inductive coupling technique does not support a very high data rate and cannot initiate a communication session from inside of the body. 2.2. In-body RF Communication Compared with the electromagnetic induction, RF communication dramatically increases bandwidth and supports a two-way data communication. The band designated for the in-body RF communication is medical implant communication service (MICS) band and is around 403 to 405 MHz. This band has a power limit of 25  µW in the air and is usually split into ten channels of 300 kHz bandwidth each. The human body is a medium that poses numerous wireless transmission challenges. It consists of various components that are not predictable and will change as the patient ages, gains or losses weight, or even changes posture. Values of dielectric constant (ÃŽ µr), conductivity (ÏÆ') and characteristic impedance (Zo) for some body tissue are given in table 1 [4]. This demonstrates that these two tissue types are very different. Also, the dielectric constant affects the wavelength of a signal. At 403 MHz, the wavelength in the air is 744mm, but in muscle with ÃŽ µr = 50 the wavelength reduces to 105mm, which helps in designing implanted antennas. 2.3. In-body Antenna Design A modern in-body antenna should be tuneable by using an intelligent transceiver and software routine. This enables the antenna coupling circuit to be optimised. Due to the frequency, and available volume, a non-resonant antenna is commonly used. It has a lower gain than a resonant antenna. This makes design of the antenna coupling circuit very important. Antenna options are dictated by the location of the implant. A patch antenna can be used when the implant is flat. Patch antennas are comprised of a flat insulating substrate coated on both sides with a conductor. The substrate is a body compatible material with a platinum or a platinum/iridium conductor. The upper surface is the active face and is connected to the transceiver. The connection to the transceiver needs to pass through the case where the hermetic seal is maintained, requiring a feed-through. The feed-through must have no filter capacitors present; these are common on other devices. An implanted patch antenna is electrically larger than its physical size because it is immersed in a high (ÃŽ µr) medium. It can be much larger electrically if the substrate is of higher (ÃŽ µr), such as titania or zirconia. A loop antenna can also be attached to the implant. This antenna operates mostly by the magnetic field, whereas the patch operates mostly by the electric field. The loop antenna delivers performance comparable to that of a dipole, but with a considerably smaller size. In addition, the magnetic permeability of muscle or fat is very similar to that of an air, unlike the dielectric constant that varies considerably. This property enables an antenna to be built and used with much less need for retuning. A loop antenna can be mounted on the case in a biocompatible structure. 2.4. In-body Link Performance The demonstration system consists of a base-station, an implant, antennas, and a controlling laptop. The base-station contains a printed circuit board (PCB) with a wakeup RF circuit, a Zarlink ZL70101 IC, and a micro-controller. It sends a wakeup signal on industrial, scientific, and medical (ISM) 2.4 GHz band to power up the implant to communicate. It also supports communication within the MICS band. The implant contains a Zarlink ZL70101 IC, a micro-controller, and a battery. The power limits of the wakeup signal for ISM and MICS bands transmitters are 100mW and 25  µW respectively. Experiments that measure the performance of an implant inside a living body are difficult to arrange. The alternative is to use 3D simulation software or a body phantom defined in [5]. The use of 3D simulation software is time consuming and hence practically not valuable. Therefore, measurements are generally performed using the body phantom and immersing a battery-powered implant into it [6]. Since no additional cables are attached to the test implant, the interference errors in the measurements are minimal. The body phantom is filled with a liquid that mimics the electrical properties of the human body tissues. The test environment is an anechoic chamber that includes a screened room. The interior walls of the room have sound-absorbent cones to minimize any reflections from walls or the floor that could distort the results. In real life, however, the results will be affected by the reflections from walls, desks, and other equipment and hardware. The body phantom is mounted on a woo den stand (non-conductive). The distance from the body phantom to the base-station is 3m. The MICS base-station dipole antenna is mounted on a stand. 1(a) shows the anechoic chamber with a body phantom (on the wooden stand), a log periodic test antenna (foreground), and a base-station dipole (right). The log periodic antenna is used to calculate the power radiated from the body phantom. A depth is defined as the horizontal distance between the outer skin of the phantom and the test implant. Vertical polarization of the implant is the case when the long side of the box and the patch antenna is vertical. The link performance is measured once the communication link is established. The measurements include the effective radiated power (ERP) from the implant, the received signal at the implant from the base-station, and the link quality. Measurements are made over a set distance with all the combinations of implant and test antenna polarisations, i.e., vertical-vertical (V-V), horizontal-vertical (H-V), vertical-horizontal (V-H), and horizontal-horizontal (H-H) polarisations. Typical results are shown in 1(b) where the ERP is calculated from the received signal power and the antenna characteristics. The measurement of the signal levels is done with the log periodic antenna and the spectrum analyzer. It can be seen in the that there is a significant difference in signal levels with polarisation combinations and depths. For a V-V polarisation, the ERP increases from a 1cm depth to a maximum between 2 and 7 cm, and then it decreases. The gradual increase is due to the simulated body acti ng as a parasitic antenna. The also shows how the signal level is affected by the depth with different polarisation. Such a test needs to be done with the antenna that is to be used in the final product. To measure the received signal at the implant, the Zarlink ZL70101 has an inbuilt receive signal strength indication (RSSI) function that gives a measure of the signal level detected. RSSI is a relative measurement with no calibration. The implant receives and measures a continuous wave signal transmitted by the base-station. In this case, the implant and the base-station antennas are vertically polarised. 1(c) shows an increase in the signal level at a depth between 3 and 4cm for a 15dec power. The power settings refer to the base-station and are cond to set the ERP to 25  µW. Signal levels are not valuable unless they are related to data transmission. One way to maintain the link quality is to measure the number of times the error correction is invoked during the transmission of 100 blocks of data. Two types of error correction codes, i.e., error correction code (ECC) and cyclic redundancy code (CRC) are invoked to maintain data integrity and reliability. The fewer ECC and CRC invocations result in better link quality. In 1(d), the error correction is lowest at a depth between 3 and 5 cm. A sample of ECC data collected at a 3cm implant depth is given in Table 2. The Count indicates the number of data blocks, the Time (ms) indicates the block transmission time, and the ECC indicates the number of times it is invoked. During the transmission of 100 blocks of data at a 3cm depth, the ECC is invoked 368 times, which is further equivalent to an average 3.68 times (as given in 1(d)). 2.5. Discussion The ERP, RSSI, as well as the ECC and CRC plots show that the implant demonstrates the best performance at a depth between 3 and 5 cm. The depth and position of an implant is not chosen for engineering performance but for the best clinical reasons. The implant designer must be aware of the possible losses through the human body. The attenuation and the parasitic antenna effects vary from patient to patient, with the position of the implant and with the time as the patient gains, or looses weight. Therefore, these factors need to be built into the link budget. 3. WBAN MAC Protocols Some of the common objectives in a WBAN are to achieve maximum throughput, minimum delay, and to maximize the network lifetime by controlling the main sources of energy waste, i.e., collision, idle listening, overhearing, and control packet overhead. A collision occurs when more than one packet transmits data at the same time. The collided packets have to be retransmitted, which consumes extra energy. The second source of energy waste is idle listening, meaning that a node listens to an idle channel to receive data. The third source is overhearing, i.e., to receive packets that are destined to other nodes. The last source is control packet overhead, meaning that control information area added to the payload. Minimal number of control packets should be used for data transmission. Generally MAC protocols are grouped into contention-based and schedule-based MAC protocols. In contention-based MAC protocols such as carrier sense multiple access/collision avoidance (CSMA/CA) protocols, nodes contend for the channel to transmit data. If the channel is busy, the node defers its transmission until it becomes idle. These protocols are scalable with no strict time synchronization constraint. However, they incur significant protocol overhead. In schedule-based protocols such as time division multiple access (TDMA) protocols, the channel is divided into time slots of fixed or variable duration. These slots are assigned to nodes and each node transmits during its slot period. These protocols are energy conserving protocols. Since the duty cycle of radio is reduced, there is no contention, idle listening and overhearing problems. But these protocols require frequent synchronization. Table 3 compares CSMA/CA and TDMA protocols. 3.1. WBAN MAC Requirements The most important attribute of a good MAC protocol for a WBAN is energy efficiency. In some applications, the device should support a battery life of months or years without interventions, while others may require a battery life of tens of hours due to the nature of the applications. For example, cardiac defibrillators and pacemakers should have a lifetime of more than 5 years, while swallowable camera pills have a lifetime of 12 hours. Power-efficient and flexible duty cycling techniques are required to minimize the idle listening, overhearing, packet collisions and control packet overhead. Furthermore, low duty cycle nodes should not receive frequent synchronization and control information (beacon frames) if they have no data to send or receive. The WBAN MAC should also support simultaneous operation on in-body (MICS) and on-body channels (ISM or UWB) at the same time. In other words, it should support multiple physical layer (Multi-PHYs) communication or MAC transparency. Other important factors are scalability and adaptability to changes in the network, delay, throughput, and bandwidth utilization. Changes in the network topology, the position of the human body, and the node density should be handled rapidly and successfully. The MAC protocol for a WBAN should consider the electrical properties of the human body and the diverse traffic nature of in-body and on-body nodes. For example, the data rate of in-body nodes varies, ranging from few kbps in pacemaker to several Mbps in capsular endoscope. In the following sections, we discuss proposed MAC protocols for a WBAN with useful guidelines. We also present a case study of IEEE 802.15.4, PB-TDMA, and S-MAC protocols for a WBAN using NS2 simulator. 3.2. Proposed MAC Protocols for a WBAN In this section, we study proposed MAC protocols for a WBAN followed by useful suggestions/comments. Many of the proposed MAC protocols are the extension of existing MAC protocols originally proposed for wireless sensor networks (WSNs). 3.2.1. IEEE 802.15.4 IEEE 802.15.4 has remained the main focus of many researchers during the past few years. Some of the main reasons of selecting IEEE 802.15.4 for a WBAN were low-power communication and support of low data rate WBAN applications. Nicolas et.al investigated the performance of a non-beacon IEEE 802.15.4 in [7], where low upload/download rates (mostly per hour) are considered. They concluded that the non-beacon IEEE 802.15.4 results in 10 to 15 years sensor lifetime for low data rate and asymmetric WBAN traffic. However, their work considers data transmission on the basis of periodic intervals which is not a perfect scenario in a real WBAN. Furthermore, the data rate of in-body and on-body nodes are not always low, i.e., it ranges from 10 Kbps to 10 Mbps, and hence reduces the lifetime of the sensor nodes. Li et.al studied the behavior of slotted and unslotted CSMA/CA mechanisms and concluded that the unslotted mechanism performs better than the slotted one in terms of throughput and lat ency but with high cost of power consumption [8]. Intel Corporation conducted a series of experiments to analyze the performance of IEEE 802.15.4 for a WBAN [9]. They deployed a number of Intel Mote 2 [10] nodes on chest, waist, and the right ankle. Table 4 shows the throughput at a 0dBm transmit power when a person is standing and sitting on a chair. The connection between ankle and waist cannot be established, even for a short distance of 1.5m. All other connections show favourable performance. Dave et al. studied the energy efficiency and QoS performance of IEEE 802.15.4 and IEEE 802.11e [11] MAC protocols under two generic applications: a wave-form real time stream and a real-time parameter measurement stream [12]. Table 5 shows the throughput and the Power (in mW) for both applications. The AC_BE and AC_VO represent the access categories voice and best-effort in the IEEE 802.11e. Since the IEEE 802.15.4 operates in the 2.4 GHz unlicensed band, the possibilities of interference from other devices such as IEEE 802.11 and microwave are inevitable. A series of experiments to evaluate the impact of IEEE 802.11 and microwave ovens on the IEEE 802.15.4 transmission are carried out in [13]. The authors considered XBee 802.15.4 development kit that has two XBee modules. Table 6 shows the affects of microwave oven on the XBee remote module. When the microwave oven is ON, the packet success rate and the standard deviation is degraded to 96.85% and 3.22% respectively. However, there is no loss when the XBee modules are taken 2 meters away from the microwave oven. 3.2.2. Heartbeat Driven MAC Protocol (H-MAC) A Heartbeat Driven MAC protocol (H-MAC) [14] is a TDMA-based protocol originally proposed for a star topology WBAN. The energy efficiency is improved by exploiting heartbeat rhythm information in order to synchronize the nodes. The nodes do not need to receive periodic information to perform synchronization. The heartbeat rhythm can be extracted from the sensory data and hence all the rhythms represented by peak sequences are naturally synchronized. The H-MAC protocol assigns dedicated time slots to each node to guarantee collision-free transmission. In addition, this protocol is supported by an active synchronization recovery scheme where two resynchronization schemes are implemented. Although H-MAC protocol reduces the extra energy cost required for synchronization, it does not support sporadic events. Since the TDMA slots are dedicated and not traffic adaptive, H-MAC protocol encounters low spectral/bandwidth efficiency in case of a low traffic. For example, a blood pressure node may not need a dedicated time slot while an endoscope pill may require a number of dedicated time slots when deployed in a WBAN. But the slots should be released when the endoscope pill is expelled. The heartbeat rhythm information varies depending on the patient condition. It may not reveal valid information for synchronization all the time. One of the solutions is to assign the time slots based on the nodes traffic information and to receive synchronization packets when required, i.e., when a node has data to transmit/receive. 3.2.3. Reservation-based Dynamic TDMA Protocol (DTDMA) A Reservation-based Dynamic TDMA Protocol (DTDMA) [15] is originally proposed for a normal (periodic) WBAN traffic where slots are allocated to the nodes which have buffered packets and are released to other nodes when the data transmission/reception is completed. The channel is bounded by superframe structures. Each superframe consists of a beacon used to carry control information including slot allocation information, a CFP period a configurable period used for data transmission, a CAP period a fixed period used for short command packets using slotted aloha protocol, and a configurable inactive period used to save energy. Unlike a beacon-enabled IEEE 802.15.4 superframe structure where the CAP duration is followed by CFP duration, in DTDMA protocol the CFP duration is followed by CAP duration in order to enable the nodes to send CFP traffic earlier than CAP traffic. In addition, the duration of inactive period is configurable based on the CFP slot duration. If there is no CFP t raffic, the inactive period will be increased. The DTDMA superframe structure is given in 2(a). It has been shown that for a normal (periodic) traffic, the DTDMA protocol provides more dependability in terms of low packet dropping rate and low energy consumption when compared with IEEE 802.15.4. However, it does not support emergency and on-demand traffic. Although the slot allocation based on the traffic information is a good approach, the DTDMA protocol has several limitations when considered for the MICS band. The MICS band has ten channels where each channel has 300 Kbps bandwidth. The DTDMA protocol is valid only for one channel and cannot operate on ten channels simultaneously. In addition, the DTDMA protocol does not support the channel allocation mechanism in the MICS band. This protocol can be further investigated for the MICS band by integrating the channel information in the beacon frame. The new concept may be called Frequency-based DTDMA (F-DTDMA), i.e., the coordinator first selects one of the channels in the MICS band and then divides the selected channel in TDMA superframe (s) according to the DTDMA protocol. However the FCC has imposed several restrictions on the channel selection/allocation mechanism in the MICS band, which further creates problems for the MAC designers. 3.2.4. BodyMAC Protocol A BodyMAC protocol is a TDMA-based protocol where the channel is bounded by TDMA superframe structures with downlink and uplink subframes as given in 2(b) [16]. The downlink frame is used to accommodate the on-demand traffic and the uplink frame is used to accommodate the normal traffic. There is no proper mechanism to handle the emergency traffic. The uplink frame is further divided into CAP and CFP periods. The CAP period is used to transmit small size MAC packets. The CFP period is used to transmit the normal data in a TDMA slot. The duration of the downlink and uplink superframes are defined by the coordinator. The advantage of the BodyMAC protocol is that it accommodates the on-demand traffic using the downlink subframe. However, in case of low-power implants (which should not receive beacons periodically), the coordinator has to wake up the implant first and then send synchronization packets. After synchronization, the coordinator can request/send data in the downlink subframe. The wake up procedure for low-power implants is not defined in the BodyMAC protocol. One of the solutions is to use a wakeup radio in order to wake up low-power implants before using the downlink subframe. In addition the wakeup packets can be used to carry control information such as channel (MICS band) and slot allocation information from the coordinator to the nodes. Finally, the BodyMAC protocol uses the CSMA/CA protocol in the CAP period which is not reliable for a WBAN. This should be replaced by slotted-ALOHA as done in DTDMA. Further details on low-power MAC protocols (originally proposed for WSNs) for a WBAN are given in Appendix I. 3.3. Case Study: IEEE 802.15.4, PB-TDMA, and SMAC Protocols for a WBAN In this section, we investigate the performance of a beacon-enabled IEEE 802.15.4, preamble-based TDMA [17], and SMAC protocols for an on-body communication system. Our analysis is verified by extensive simulations using NS-2. The wireless physical parameters are considered according to a low-power Nordic nRF2401 transceiver (Chipcon CC2420 radio [18] is considered in case of IEEE 802.15.4) [19]. This radio transceiver operates in the 2.4-2.5 GHz band with an optimum transmission power of -5dBm. We use the shadowing propagation model throughout the simulations. We consider a total of 7 nodes firmly placed on a human body. The nodes are connected to the coordinator in a star topology. The distribution of the nodes and the coordinator is given in 3(a). The initial nodes energy is 5 Joules. The packet size is 120 bytes. The average data transmission rate of ECG, EEG, and EMG is 10, 70, and 100 kbps. The transport agent is a user datagram protocol (UDP). Since the traffic is an uplink t raffic, the buffer size at the coordinator is considered unlimited. In a real WBAN, the buffer size should be configurable based on the application requirements. For energy calculation, we use the existing energy model defined in NS-2. The simulation area is 33 meter and each node generates constant bit rate (CBR) traffic. The CBR traffic is an ideal model for some of the medical applications, where the nodes send data based on pre-defined traffic patterns. However, most of the nodes in a WBAN have heterogeneous traffic characteristics and they generate periodic and aperiodic traffic. In this case, they will have many traffic models operating at the same time, ranging from CBR to variable bit rate (VBR). 3(b) shows the throughput of the IEEE 802.15.4, PB-TDMA, and S-MAC protocols. The performance of the IEEE 802.15.4, when cond in a beacon-enabled mode, outperforms PB-TDMA and S-MAC protocols. The efficiency of a MAC protocol depends on the traffic pattern. In this case, S-MAC protocol results poor performance because the traffic scenario that we generated is not an ideal scenario for the S-MAC. 3(c) shows the residual energy at various nodes during simulation time. When nodes finish their transmission, they go into sleep mode, as indicated by the horizontal line. The coordinator has a considerable energy loss because it always listens to the other nodes. However, the energy consumption of the coordinator is not a critical issue in a WBAN. We further analyze the residual energy at the ECG node for different transmission powers. There is a minor change in energy loss for three different transmission powers as given in 3(d). This concludes that reducing the transmission power only d oes not save energy unless supported by an efficient power management scheme. The IEEE 802.15.4 can be considered for certain on-body medical applications, but it does not achieve the level of power required for in-body nodes. It is not sufficient for high data rate medical and non-medical applications due to its limitations to 250 kbps. Furthermore, it uses slotted or unslotted CSMA/CA where the nodes are required to sense the channel before transmission. However, the channel sensing is not guaranteed in MICS band because the path loss inside the human body due to tissue heating is much higher than in free space. Bin et.al studied the clear channel assessment (CCA) range of in-body nodes which is only 0.5 meters [20]. This unreliability in CCA indicates that CSMA/CA is not an ideal technique for the in-body communication system. An alternative approach is to use a TDMA-based protocol that contains a beacon, a configurable contention access period (CCAP), and a contention free period (CFP) [21]. Unlike the IEEE 802.15.4, this protocol is required to use a slot ted-ALOHA protocol in the CCAP instead of CSMA/CA. The CCAP period should contain few slots (3 or 4) of equal duration and can be used for short data transmission and a guaranteed time slot (GTS) allocation. To enable a logical connection between the in-body and the on-body communication systems, a method called bridging function can be used as discussed in [21]. The bridging function can integrate in-body and on-body nodes into a WBAN, thus satisfying the MAC transparency requirement. Further details about bridging function are given in [22]. 3.4. Discussion Since the CSMA/CA is not suitable due to unreliable CCA and heavy collision problems, it can be seen that the most reliable power-efficient protocol is a TDMA-based protocol. Many protocols have been proposed for a WBAN and most of them are based on a TDMA-based mechanism. However, all of them have pros and cons for a real WBAN system that should operate on Multi-PHYs (MICS, ISM, and UWB) simultaneously. The MAC transparency has been a hot topic for the MAC designers since different bands have different characteristics in terms of data rate, number of channels in a particular frequency band, and data prioritization. A good MAC protocol should enable reliable operation on MICS, ISM, and UWB etc bands simultaneously. The main problems are related to MICS band due to FCC restrictions [23]. According to FCC, â€Å"Within 5 seconds prior to initiating a communications session, circuitry associated with a medical implant programmer/control transmitter must monitor the channel or channels the MICS system devices intend to occupy for a minimum of 10 milliseconds per channel.† In other words, the coordinator must perform Listen-before-talking (LBT) criteria prior to a MICS communication sessions. The implants are not allowed to

Moma Visit – Compare and Contrast Paintings

MoMA visit – Visual analysis Art is an effective way to express beauty. Artists have different ways to express their ideas and communicate nonverbally through their work. In the Early Modern Art period, artists were free to create their pieces in diverse ways that never had been done before. For this essay, I chose the works of two artists of this period to compare and contrast so that the diversity of Modern art can be demonstrated.Even though Vincent Van Gogh and Rene Magritte was born forty five years apart from each other and had different styles, I am interested in analyzing â€Å"The Starry Night† (Vincent van Gogh) and â€Å"The Empire of Light, ii† (Rene Magritte) after my trip to the Museum of Modern Art. At the first analysis, I would like to discuss the famous painting â€Å"The Starry Night† (1889) by Van Gogh. This painting is in oil on canvas and has the dimensions of 73. 7  cm ? 92. 1  cm. Van Gogh depicts the town in Rhone under gasligh t and reflected in the blue river.As it is displayed at MoMA, â€Å"The Starry Night† attracts a great number of visitors to its mysterious blue spirals. The focus of the painting is quite high as the first point drawn to the viewer is at the sky. The spirals meet with each other and the yellow stars are bright throughout the dark blue sky. Van Gogh uses thick brush strokes to draw the mysterious spirals, which occupy most of the center of the painting. The enormous spirals are reproduced images of moving waves in the ocean, but also induce a whirling movement. This technique plays a significant part to create the chaotically moving effect for the picture.Most people who see this picture for the first time feel that the whole scenery somehow shifts, even though it is a still life painting. Moving my view point from the mysterious spirals, I can see the big, extremely dark green cypress tree located in the right part of the picture. Cypress appears in Van gogh’s picture often such as in the â€Å"Cypresses† and â€Å"Wheatfield with cypresses. † Unlike these two pictures above, he uses similar sinuous curves tortured from full cycles one after another in this one to reproduce the brush stroke he uses in the spirals.In the bottom one third of the painting, Rhone town at midnight is peaceful in blue. The clearest part we can see at this town is the church and its bell tower. Although the church only consists of simple sketches, it seems to be the most complicated fragment in the painting. The bell tower points up to the sky and draws attention of the viewers to the spirals once again. Secondly, the next painting I would like to mention is â€Å"The Empire of Light ii† (1950) of Rene Magritte. Its dimensions are of 78. 8 x 99. 1 cm. Magritte wants to demonstrate a nocturnal scene under a daytime sky.When I first saw the painting, the initial thought that came through my mind was to admire the peaceful scenery of an ordinary small town. Then I noticed the paradox in the painting. The upper half of the painting is the light blue sky of a peaceful day with floating white clouds. However, the bottom half is a small town at midnight. Houses and trees are all covered with dark hue as if it is late at night. The town looks as if it has already gone to sleep. The thin and precise brush strokes that Magritte adroitly use make the picture look as real as a photo. The closer and longer I look at the painting, the more confused I become.The serenity of the deep-sleeping town, which is dimly lit by the antique street light, along with the floating clouds, makes me feel so calm and peaceful that I am persuaded into its reality. However, I am still able to notice the contrast between day and night in two halves of the painting. This confusion is the result of the eyes tricked to believe in what we see. The placement of day and night remarkably reminds us about our conscious mind that we use in everyday life, and about our lit unconscious mind that waits for us to use it to brighten our senses.This painting conceals Magritte’s psyche that â€Å"The mind loves the unknown. It loves images whose meaning is unknown, since the meaning of the mind itself is unknown. † On the one hand, there are similarities between two paintings that I notice. Firstly, both painters use oil on canvas for the paintings. They also have the approximate dimensions of about 70cmx95cm. Secondly, mystery is an important fact that makes the two paintings worth seeing. People cannot resist taking a look at the spirals and following the moving effect of the whole picture when seeing â€Å"The Starry Night. The spirals themselves are mysterious since they are echoed the movement of ocean waves. Similarly, ‘The Empire of Light, ii† makes spectators wonder the reality of a nocturnal scene of a small town under a sunny day. Their minds are tricked to believe in the true-to-life scene as well as to question th e paradox. In addition, luminosity is created successfully in two paintings. In â€Å"The Starry Night†, the moon and the stars illuminate the sky as stars and moon are in concentric circles and contrary to the dark blue sky surrounding.The moon is placed at the top right corner of the painting, where the sun usually appears, and produces light together with the stars. Correspondingly, in Magritte’s, light comes from the title of the painting itself. The lamppost, as well as the windows’ dim light, creates the luminosity standing alone in the dark night. Finally, even though both paintings have no sign of human and animals, motion still appears clearly. The whole â€Å"Starry Night† is a chaos, moving and moving freely, while the floating clouds in the sunny sky in the upper half of the painting prevents â€Å"The Empire of Light, ii† from lacking in movement.On the other hand, each picture has its own quality. The first difference between the two paintings is the brush stroke. Vincent van Gogh uses the thick brush stroke in â€Å"The Starry Night,† especially when painting the spirals and the cypress, while Magritte’s extremely thin brush stroke appears everywhere in the painting. As a result, the surfaces of two paintings are different; rough in â€Å"The Starry Night† and smooth in â€Å"The Empire of light, ii. † Also, while â€Å"The Starry Night† has an open shape, â€Å"The Empire of Light, ii† is closed-shaped. In â€Å"Starry Night,† there are no edges coming between the stars and the sky.They just merge with one another and create a beautiful â€Å"Starry Night. † However, the thin brush strokes in â€Å"The Empire of Light† identify all objects distinctively. Edges are clear between houses; clouds and sky are clearly recognized. Thirdly, although both painters use blue, the hue, value and intensity are different. Blue is the spiritual color in â€Å"Th e starry night,† and Van Gogh uses blue that varies from the darkest in the town to the lightest in the inside of the spirals. Blue is also diverse in the sky, together with yellow to make a sky lively.Magritte, however, uses just one value of light blue to paint his sky in a sunny day and the sky looks serene. Last but not least, even though both paintings depict the same subject of a small town at midnight, each painting represents a different style. While â€Å"the starry night† of Van Gogh follows post-impressionism – a style that combines the elements of Impressionism with those of non-Europe to create their own way – â€Å"The Empire of Light, ii† of Magritte is surrealist, whose purposes are to describe the irrational, to examine perception and to create the word and image relationship.In conclusion, â€Å"The starry night† of Vincent van Gogh and â€Å"The Empire of Light, ii† are expressions of aesthetic values. The paintings, either post-impressionist or surrealist, represent the painters’ own way of self-expression and their own way to communicate with the spectators nonverbally. Reference 1. Van Gogh’s letters http://vangoghletters. org/vg/letters/let693/letter. html http://vangoghletters. org/vg/letters/let782/letter. html 2. Magritte’s quotes http://www. rene-magritte. org/rene-magritte-quotes. jsp 3. Other http://www. moma. org/collection/object. php? object_id=78456 http://www. all-art. rg/art_20th_century/magritte1. html The starry night – Vincent van Gogh The Empire of Light, ii – Rene Magritte Claude Monet – Contextual factors influenced his style Claude Monet (1840-1926) was a French artist, who was considered a leader of the Impressionism movement as this style was named after his painting â€Å"Impression, Sunrise† (1872). He is one of the typical artists to mention when we discuss the Early Modern art era. I would like to analyze the contextu al factors that affect his style of painting. First of all, the political circumstances in France from 1870s had effects on Monet’s style.During the Franco-Prussian War (1871-1872), Monet came to England with Pissarro for shelter. He met the dealer Durand Ruel, who then became a great advocator of the Impressionists. Also in England, Monet had chance to study the works of John Constable and Joseph Mallord William Turner, which inspired his innovations in study of colors. After spending a summer (1971) in Amsterdam, Holland, he returned to French, which was damaged by the civil war. He stayed in Argenteuil, which was an industrially growing town near the Seine river until 1878.From 1872-1878, Argenteuil was a center for Impressionist painters to gather after Monet published his painting â€Å"Impression, Sunrise† depicted the Seine river. In addition, innovations in painting manufacture were introduced in public in 19th century. In 1841, John Rahn invented the collapsib le tin paint tube, which revolutionized the color palette and technique of  plein-air oil painting  by offering a range of pre-mixed colors in a convenient medium. This is a major factor to emerge Impressionism. Monet used this plein-air painting as a elementary principle of his art in 1860s,.He sought to combine his Realist investigation with the possibilities of creating a new style of painting. In the paintings produced at La Grenouillere at 1869, Monet found a way establish a challenging tension between appearances and painterly invention that proved sufficient basis for the developed Impressionist manner of the 1870s and after. In 1870s, Monet’s brush stroke became smaller and more diverse. He also tried to conduct experiments to control value contrasts. These experiments with color were played off against and within a traditional framework, essentially perspectives in nature.Finally, 19th century marked the emergence of photography, which had a major effect on Moder n Art. In the first half of the century, cameras were introduced continuously and rapidly improved. For example, in 1814, Joseph Niepce used his  camera obscura  to take picture, but the image required eight hours of light exposure and later faded. In 1851, Frederick Scott Archer invented the  Collodion process, in which images required only two or three seconds of light exposure. Thus, painters were in need of seeking new techniques to innovate their painting. They had to prove that paintings might not be replaced by photos.Thus, Monet sought a way to break the old rules of traditional painting. His brush strokes became thinner; the closed shape in traditional painting became more open as the boundaries between objects were more obscure, as we can see in his â€Å"Impression, Sunrise. † According to the contemporary critics, the painting was rather a sketch than a complete work of art. However, this painting was the first impressionist to be presented. In conclusion, t he political circumstances and developing technique are two crucial factors that affect the style of Monet Claude.After his first painting in 1972, Impressionism became his style for his later life. Work cited MoMA – Monet Claud’s biography http://www. moma. org/collection/artist. php? artist_id=4058 http://www. claude-monet. com/index. jsp House, John, et al. :  Monet in the 20th century, page 2, Yale University Press, 1998 http://www. visual-arts-cork. com/artist-paints/colour-palette-nineteenth-century. htm http://library. brown. edu/cds/paris/finearts. html#impressionism http://inventors. about. com/od/pstartinventions/a/Photography. htm

Music Appreciation Essay

1. What are figured bass and basso continuo? How are they related? Figured bass is a musical notation using numbers to indicate chords, intervals, and other aspects in relation to the bass note of the music and basso continuo is the harmony of the music itself. (this has nothing to do with the question; when I took AP music theory, figured bass was my favorite thing to do!) 2. What is ornamentation? Ornamentation is the use of non-necessary musical flourishes, such as trills and grace notes, to the basic melody or harmony. 3. What is an oratorio? How does it differ from an opera? Oratorios are basically just concerts, whereas operas are more theatrical. Oratorios have a different focus and don’t use scenery like operas. 4. What is an orchestra? How did the development of orchestras influence Baroque music? Orchestras are larger instrumental ensembles or groups that contain brass, string, percussion, and woodwind instruments. The development of orchestras brought along the development of new instruments, like the violin and cello & it also brought along the composition of orchestral music specifically. 5. What is an instrumental suite? A composition that consists of a succession of short pieces, forming into a large composition. Critical thinking questions: 1. What are the characteristics of Baroque music? How would you describe Baroque music? Baroque music is defined as â€Å"that in which the harmony is confused, charged with modulations and dissonances, the melody is harsh and little natural, the intonation difficult, and the movement constrained† (Jean-Jacques Rousseau). To me, baroque music is highly eccentric and decorative; extremely difficult and concise, yet beautiful all at the same time. 2. Choose one of the composers discussed in the unit and listen to several of the composer’s works. Which works did you listen to? How would you describe this composer’s music? Why do you think this composer was an influential figure in Baroque music? I chose to listen to one of my favorite composers of all time, Antonio Vivaldi. I listened to The Four Seasons (every season & every movement). I find his compositions astounding, able to tell stories without the use of words. Small things such as the incorporation of animals and sounds from nature truly paint a picture in the mind. In addition to this, the sudden change from a soothing violin soloist playing to a group of string instruments playing at once completely dramatizes the piece, making it more meaningful. Overall, I believe Vivaldi is an amazing composer, who was highly influential in the Baroque period due to his use of mostly stringed instruments, and he was highly innovative. His music was highly decorated and creative, and in most cases, very melodic and smooth. Vivaldi continues to be an influential composer to this day. 3. How did composers and musicians think about themselves during the Baroque period? How did this influence the music that they created? 4. What advantages and disadvantages did Baroque composers have in the patronage system? What did they gain from this practice? What limitations did it place on them? They were able to showcase their musical genius, yet they were limited to what they were able to play because of what the patron wanted to hear. They did gain a lot of fame and publicity through the patronage system despite the limitations that were placed on them. 5. Baroque music often tried to capture and reflect a particular emotion or feeling. Choose one of the musical works in the unit. Identify the work that you chose. What feeling or emotion is the composer trying to capture or reflect in the work? What aspects of the music lead you to this emotion or feeling?

Video Games Effects On Children - 906 Words

Video games have become an important part of children lives these days. As parents we need to help our children spend a reasonable amount of time on gaming. Allowing too much time on video games can hinder a child’s developmental process. Obsessive amounts of video game playing can cause; attention span problems, inhibit social interaction, aggression, poor social skills, and games are not intellectually stimulating. Parents need to take control and limit the time their children spend on video games each day. Paying Attention School children already have enough on their plates while in school and need to pay as much attention as they can to their teachers. Sixty-seven percent of elementary children are more liable to have attention span problems from playing video games for more than two hours (Klein, 2010). Some parents seem to believe that video games will not harm their attention like TV does. Researchers say that children who watch TV or play games for long periods struggle to pay attention to their teachers while at school (Klein, 2010). Parents will even say that video games do not affect their children’s attention because they can sit for hours playing with no problem. Dr. Ron Steingard, says â€Å"Continuous activity doesn’t mean sustained attention†. Dr. Steingard, also states that â€Å"The task is changing so rapidly, shorts burst of attention are all that’s involved† (Miller, n.d., para. 6). Yalda Uhls, a senior researcher with the UCLA’s Children’s Digital Media Center,Show MoreRelatedThe Effects Of Video Games On Children Essay1279 Words   |  6 PagesIntroduction Video games have always been a controversial type of entertainment, that may come from how relatively new video games are compared to other mediums of entertainment[1]. Maybe because of that when a violent crime occurs and the culprit has played a lot of games the media is quick to point at violent games as the reason for the crime, but is that true or are the media just biased or looking for quick views, this report aims to answer that question. Do games affect our way of thinkingRead MoreEffects Of Video Games On Children Essay1357 Words   |  6 PagesScreening to a halt: Are parents in New Zealand able to identify signs of dependency or addiction in their children due to over use of screen-time from the recreational use of video games? Digital technology and the vast amount of video games have increased the amount of screen time consumption in contemporary New Zealand society. The saturation of smart phones, ipad’s, tablets, computers, game consoles and the Internet are devices with the means of connection to gaming. Many New Zealand families integrateRead MoreThe Effects of Video Games on Children1288 Words   |  6 PagesThe Effects of Video Games on Children Technology today has progressed rapidly from generation to generation. Children and young adults are both into video games and the latest gadgets out there. Video games have been available to customers for the last 30 years. They are a unique way to entertain individuals because they encourage players to become a part of the games script. Victor Strasburger an author of â€Å"Children, Adolescents, and the media† stated â€Å"The rising popularity of video games hasRead MoreThe Effects of Video and Video Games on Children2043 Words   |  8 Pagesaction, usually in a cartoon, movie, or video game. For many of us, Disney is where we refer back to early forms of animation with the idea of using thousands of consecutive drawings; through Disney, we can now see how far this idea of breathing life into static objects has advanced. Today, animation is becoming more and more realistic. With highly advanced technology and computer programs, it has become easier for simple cartoons to develop into what children see as real life. These animated cartoonsRead MoreThe Effects Of Video Games On Children1548 Words   |  7 PagesVideo Games Introduction Today video games are a staple in most households. It is pretty amazing to know that the first creation of games date all the way back to the 1900s. They were not originally invented to make a profit, but to give patients something to do while waiting in the lobby of an office. One inventor had a simple idea of using the monitor not just as a television set, but as a way to play games. College students were just playing around with equipment and happened upon something greatRead MoreVideo Games And Its Effects On Children927 Words   |  4 PagesVideo games are a more interesting form of entertainment for the simple reason that players may become part of the game’s plot. Video games were invented for many years now. However, the current variety of games raised concerns about how they affect the children s behavior due to the fact that the games are becoming more sophisticated. Children spend most of their free time playing video games. Sometimes children refrain from completi ng important duties and dedicate all of their time playing videoRead MoreVideo Games And Its Effects On Children940 Words   |  4 Pageswas bored they went outside to play, they created new games, or they played with friends. But, for the past three decades, video games and other digital media have been persuading many adolescents and children to spend the majority of their time playing them. Video games seem to satisfy children’s natural need to interact socially, however more often than not, they lead to social isolation. Overexposure to digital media, such as video games is detrimental to the health and function of a child’sRead MoreVideo Games And Its Effects On Children1519 Words   |  7 PagesVideo games in the 21st century have transformed from friendly competing into guns, explosions, and major violence. Video games are getting away with more violence every year and the games are becoming more extreme. The consistence and severity of violence is at an a ll-time high leading the most popular games in the gaming community to have a ‘mature’ rating due to the considerable amount of violence involved. For example, one of the highest selling video games of all time grossing one billion itsRead MoreThe Effects of Video Games on Children1656 Words   |  7 PagesIntroduction For more than 30 years, video gaming has been a popular activity amongst many of America’s children. With over $63 billion (Reuters, reuters.com) worth sold each year, video games are here to stay. While much controversy has arisen over the subject, video games have benefited the United States of America and its citizens to a great degree. For example, the military and CIA use gaming to train soldiers (Davidson, www.ehow.com), and classrooms use video games to teach students. The potentialRead MoreThe Effects Of Video Games On Children1034 Words   |  5 PagesThe world of today has developed in a way that even children are affected by technology. They enjoy video games in their leisure time and even prefer them to studying that, in its turn, can contribute to their poor performance in the class. These days, video games have become an issue that has brought concern to many people from parents to scholars about their potential effect on the future of children through influenci ng their conduct. They feel that the violent behavior or any other negative consequence

The Effects of Alcohol Consumption on College Students

The Effects of Alcohol Consumption on College Students On a weekly basis, college students consume more alcohol to fit in with their peers. Prior research has shown how alcohol consumption can lead to negative effects. Typically, college students ignore the negative effects of consuming alcohol, in order to have a good time. College students are the point in their life where they are searching for new and exciting ways to fit in and have fun amongst peers. Alcohol consumption among college student is an important community and public health concern. Drinking appears to be a normal part of the college experience and is related with high-risk behavior, such as driving†¦show more content†¦Although students drink for a variety of reasons (Baer, 2002), peer pressure plays an important role in maintaining these patterns. Peer pressure has three forms: explicit offers of alcohol, role modeling, and social norms (Borsari Carey, 2001). Women may report greater discrepancies between how much they think others are drinking and their ow n levels of alcohol consumption because they use men as a frame of reference when responding to questions about the typical student s drinking habits (Borsari Carey, 2003; Korcuska Thombs, 2003; Lewis Neighbors, 2004). Alternatively, the gender difference in other self- gap scores may reflect a greater susceptibility to peer pressure among males. In their longitudinal analysis of other-self discrepancies in perceived comfort with campus drinking practices, Prentice and Miller (1993) found that males were more likely than females to adopt attitudes toward alcohol use that matched what they believed to be normative. Women are also more likely than their male counterparts to state that they would be able to resist situational pressures conducive to drinking in a variety of hypothetical situations (Shore et al., 1983). Presumably this is due to the fact that men experience more pressure from others to drink. Students themselves acknowledge this gender difference. They also believe that women are more inclined to sufferShow MoreRelatedEffects Of On Campus Housing On College Students Drinking Behavior1565 Words   |  7 PagesEffec ts of on-campus housing on college students’ drinking behavior: A Literature Review Educational scholars have widely researched the effects of on-campus housing on the behavior of college students and one of the behavioral effects is on drinking behavior. Researchers from both the United States and New Zealand have found that students living in residential halls on campus demonstrate the greatest rates for drinking and peer pressure for drinking (Rickwood, et al., 2011.). Leontini, et al.Read MoreAlcohol Use, Abuse, And Related Accidents Among College Adults1412 Words   |  6 PagesQuestion: Alcohol uses among college students-What are the trends in alcohol use, abuse, and related accidents among college aged women versus men? Background National Institute on Alcohol Abuse and Alcoholism (NIAAA) defines low risk drinking as less than 4 drinks in a day.1 On the other hand, binge drinking as a pattern of drinking makes blood alcohol concentration (BAC) level to 0.07h/dL. This level is typically reached after 4 drinks for women and 5 drinks for men in approximately 2 hours. DrinkingRead MoreAlcohol Is The Drug Of Choice Among Youth1692 Words   |  7 Pagesto become addicted to alcohol and drugs? Or why is age of first use of alcohol is critically important? There are many questions raised on consumption of alcohol when it comes on drinking at early age. Alcohol often has a strong effect on people and throughout history, we have struggled to understand and manage the power of alcohol. However, we hardly think how much alcohol is too much for us, unless we get into any kind of trouble or shows some physical or mental effects on our health. Read MoreEffects Of Alcohol Awareness Programs On College Students1594 Words   |  7 Pages Effects of Alcohol Awareness Programs on College Students Valerie Love Grand Canyon University: PSY-550 October 2, 2015 Abstract In this paper, the effects of alcohol awareness programs on college students will be discussed. The discussion and study will be based on the before and after effects of alcohol awareness programs on college students. The study presents a CBT (Cognitive Behavior Therapy), or an Alcohol 101 Psych-Education CD-ROM to a randomly assigned group of 113 college studentsRead MoreAlcohol Consumption Among Athletes and Non-Athletes Essay1395 Words   |  6 PagesAlcohol Consumption Among Athletes and Non-Athletes On college campuses, the consumption of alcohol amongst undergraduate college students continues to be a maladaptive college health behavior. The recreational use of alcohol effects the student population and the health of the students who excessively drink alcohol. The issue caused many research studies to focus on the effect of alcohol consumption based on being an athlete and non-athlete. This study is important because it provides college campusesRead MoreA Study of College Drinking Essay examples1497 Words   |  6 PagesReview of Literature The literature on college binge drinking and student’s academic performance are for the most part; focused on an essential constituent or characteristic that has been revealed. During the past ten months, research has become an essential basis in regards to college binge drinking and the effects said behavior is having on those college students who choose to over-indulge. Given the situation over the literature pertaining to college binge drinking and poor academic grades,Read MoreUnderage drinking1086 Words   |  5 PagesUnderage alcohol consumption can be very common in the weekly routine for many students. There are many different types of drinkers and reasons for their drinking habits. Some people may drink for social reasons and others may have an alcohol problem. Underage alcohol consumption is serious among students in high school and college; it can cause health issues, and legal problems. Alcohol can be very addictive and excessive consumption could be detriment al to a person in numerous ways. Alcohol abuseRead MoreThe Legal Drinking Age Act1179 Words   |  5 Pagesage and whether it should lower from twenty-one, or remain. On July 17, 1984, Ronald Reagan was in office when the National Minimum Drinking Age Act was passed, prohibiting anyone under the age of twenty-one from publicly possessing and purchasing alcohol. After the Act was passed in 1984, the states that failed to abide by Ronald Reagan’s National Minimum Drinking Age Act were withheld from federal highway construction funds. By creating this punishment, states were almost forced to comply with theRead MoreUnderage Alcohol And Alcohol Abuse1597 Words   |  7 Pagesdrug and alcohol abuse in schools whether its at the high school or college level. Not only does drug and alcohol consumption effect your overall health, it can effect your academic performance as well. In this paper I am going to be talking about the problems with drug and alcohol abuse, preventions, risks, costs and much more. We are goi ng to dissect the problems with drug alcohol consumption amongst young adults, from high school to college, and I will be talking about how students are gettingRead MoreBinge Drinking Among College Students And Its Implications On The Society1462 Words   |  6 PagesBinge Drinking among College Students and Its Implications on the Society Binge drinking is a term used to describe a situation where women drink more than 4 bottles of alcohol in a row and men drink 5 or more bottles of alcohol in a row. It is taking too much alcohol in a short period. Alcohol is a substance that gradually produces an addiction in the body. Many college students use alcohol in recreational activities and parties. The alcohol gradually leads to addiction and causes a decline in their

Capital Punishment And Its Impact On Society - 1292 Words

Capital punishment has and will continue to be a controversial subject. There are many that vehemently oppose its function, while others adamantly support it use, especially when confronted with horrific crimes. The sanctioning of death for the punishment of murder and other heinous acts in the United States has declined in recent years. However, many advocate that the United States, who remains the most advanced democratic nation, fails to recognize that capital punishment is a profound violation of human rights. There are many factors that weigh heavily on the productivity of our culture, specifically its impact on society, in terms of populace content and ineradicable norms. Theories in sociology provide us with different perspectives to view our past and current social structure. A perspective is simply one’s beliefs in how they view the world, which includes but are not limited to, the right way to punish society’s most violent offenders. Throughout this essay, we will explore two main points: first, capital punishment’s role in society, and second, how it evolves and continues to sustain its core principles in U.S society. Sociological perspectives is an echoed term, which is divided into three major factors: â€Å"†¦symbolic interactionism, functionalism, and conflict theory† (Chambliss Eglitis, n.d.). Conflict theory is a theory that claims society is in a state of perpetual conflict due to competition for limited resources. It holds that social order isShow MoreRelatedCapital Punishment and the Media1249 Words   |  5 PagesCapital Punishment and the Media Xavier Mendez Professor Collica JUS110 September 12, 2011 Capital Punishment and the Media In today’s society, the capital punishment known as the death penalty has played a major role in the criminal justice system. It has brought important debates to the national attention in every aspect to whether end the lives of criminals. With the intense media coverage, it raised high standards on disputes on high profile cases such as serial killers. The attentionRead MoreThe Death Penalty And Its Effects On Society826 Words   |  4 PagesThe death penalty is still a major topic even in today’s society. In this short paper I am going to analyze the Supreme Court decision and how it influences the death penalty, the financial impact on society, and social impact of the death penalty on society. The death penalty does cause a financial burden on society to the point that a state can go bankrupt. The death penalty need to be handed down on case by case bases. Moreover, it cheaper to just give a sentence of life without parole. Read MoreCapital Punishment And Its Effect On The Economy Of United States1320 Words   |  6 Pagesof society. As society grew more complex, many different factors influenced the development of the death penalty, or capital punishment as it has developed into in the United States. Because of this, controversy about whether or not to have the punishment arose, leading to much debate on the topic. The paper will analyze and observe the Capital Punishment and its influence on the economy of United States. Before proceeding, it is important to note that the definition of the capital punishment: aRead MoreTaking a Look at Capital Punishment1003 Words   |  4 PagesCapital punishment is a topic highly debated upon. For years the court systems have been debating whether the criminals deserve this strict punishment or not. However, despite the verdict from the judge, people have still been divided on whether capital punishment does more harm than good. A major subject that comes up is if the government has a justifiable reason for killing convicted people. Some only look at the negative but there are plenty of reasons why this is a positive action. Capital punishmentRead MoreCapital Punishment and its Controversies 1434 Words   |  6 PagesCapital punishment uses death penalty as a form of punishment in many states and countries. It is a practice that has raised endless questions all over the world. Capital punishment or death penalty policy has changed in many countries overtime. Countries such as, New Australia, Zealand and 15 states in the US do not have capital punishment. One of the major concerns arising with capital punishment is because it causes ending of a human life. People and organizations of different backgrounds areRead MoreEssay on The Death Penalty1543 Words   |  7 PagesCapital Punishment The Death Penalty In the United States many crimes are committed every day, people killing another person, raping innocent children. I strongly believe that people who committed a crime should be punished and punished harshly and those who commit harm to another person should die. The Capital Punishment is a controversial topic that affects society as a whole and causes a great deal of disagreement. Capital punishment is the government legally kills an individual as punishmentRead MorePersuasive Essay On Capital Punishment1621 Words   |  7 PagesThe use of capital punishment in the United States has been the center of a heated debate for nearly six decades. Prior to the 1960’s society accepted the idea that the interpretation of the fifth, eighth, and fourteenth amendment permitted the use of capital punishment; however, it was suggested in the 1960’s that capital punishment constituted â€Å"cruel and unusual punishment†. (www.deathpenaltyinfo.org) â€Å"In 1958, the Supreme Court had decided that the Eighth Amendment contained an evolving standardRead More Capital Punishment Essay949 Words   |  4 PagesCapital Punishment   Ã‚  Ã‚  Ã‚  Ã‚  Capital punishment is a very controversial issue, but it is a just penalty for murderers. Murderers forfeit their lives for taking the life of another. Capital punishment deters criminals from committing violet crimes. Incapacitating criminals is also another form of deterrence. The death penalty removes harmful criminals from society. In doing this, people can feel much safer knowing that there is one less criminal on the streets. The death penalty is also more economicalRead MoreCapital Punishment And Its Economic, Political, And Social Impact On The United States Of America1739 Words   |  7 PagesINTRODUCTION Capital punishment, also frequently referred to as the  death penalty, is a government certified practice where a person is put to death by the state as a form of punishment for a crime they have committed (Henderson, 25). Crimes that are found punishable by death are referred to as  capital crimes  or  capital offences, and commonly include offences such as murder, treason, war crimes, crimes against humanity and genocide (Henderson, 48-9). The term  capital  is derived from the  Latin termRead MoreThe Death Penalty Is Necessary899 Words   |  4 Pagesone can look into human civilization, justice for a murder victim has always been by taking the life of the killer. In today’s society capital punishment is needed to defend it from further harm, bring justice and/or vengeance to the victims of the loved ones, and encourage psychological deterrence. As of today, there are thirty-two states which offer the only just punishment for a crime without parallel and eigh teen states having abolished the death penalty. The use of the death penalty has brought