Recently, the IEEE 802.15.6 Task Group introduced a new wireless communication standard that provides a suitable framework specifically to support the requirements of wireless body area networks (WBANs). The standardization dictates the physical (PHY) layer and medium access control (MAC) layer protocols for WBAN-based communications. Unlike the preexisting wireless communication standards, IEEE 802.15.6 standardization supports short-range, extremely low power wireless communication with high quality of service and support for high data rates upto 10 Mbps in the vicinity of living tissues. In this work, we construct a discrete-time Markov chain (DTMC) that efficiently depicts the states of an IEEE 802.15.6 CSMA/CAbased WBAN. Following this, we put forward a thorough analysis of the standard in terms of reliability, throughput, average delay, and power consumption. The work concerns non-ideal channel characteristics and a saturated network traffic regime. The major shortcoming of the existing literature on Markov chain-based analysis of IEEE 802.15.6 is that the authors did not take into consideration the time spent by a node awaiting the acknowledgement frame after transmission of a packet, until time-out occurs. Also, most of the work assume that ideal channel characteristics persist for the network which is hardly the case in practice. This work remains distinctive as we take into account the waiting time of a node after it transmits a packet while constructing the DTMC. Based on the DTMC, we perform a user priority (UP)-wise analysis, and justify the importance of the standard from a medical perspective.

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This paper proposes an improvement for beacon enabled IEEE 802.15.4 medium access control (MAC) protocol for better energy consumption, reliability and synchronization among the sensors. First, we suggest an improved model over the existing beacon enabled IEEE 802.15.4. The modified IEEE 802.15.4 MAC protocol is modeled through a Markov chain using retry limits, acknowledgements and a new parameter namely 'number of sleep slots'. Second, in beacon superframe structure there is an inactive period, which is used by sensors during sleep mode; the random sleep time for each sensor reduces the reliability of the network. We have proposed an optimized sleep time which divides the inactive period into number of slots in which the sensor utilizes a single slot in the sleep mode and then returns to the idle state. Third, sensors are synchronized by periodic transmission of beacon superframe from personal area network (PAN) coordinator. We have modified this by an adaptive synchronization method. We have simulated our suggested model in ns 2.34 to test the performance. The performance of our model is compared with the existing model for different performance metrics as reliability, data packet collision probability, data transmission failure probability and energy consumption of the sensors.

This paper proposes a redefined multiple access control (MAC) protocol of IEEE 802.15.4 standard, incorporating an adaptive synchronization algorithm with optimal sleep period. The modified standard, namely AS 802.15.4 provides better power consumption, reliability and synchronization among the sensors than the existing protocol. AS 802.15.4 MAC protocol is modelled using a four dimensional Markov chain using backoff stage, backoff counter, retransmission limits, and a new parameter namely number of sleep slots. Using the Markov chain we have calculated different performance metrics as reliability, data packet collision probability, data transmission failure probability, power consumption, throughput and average packet delay for comparison between the existing and redefined protocol. We have simulated our modified protocol in ns 2.35 to compare the simulation result with the calculated result of the performance metrics. The performance of modified protocol is compared with the existing protocol for different performance metrics. We observe that our modified MAC protocol gives significant better performance than the existing MAC protocol.

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