Abstract
Due to the recent development in the field of Wireless Sensor Networks (WSNs), the Wireless Body Area Networks (WBANs) have become a major area of interest for the developers and researchers. Human body exhibits postural mobility due to which distance variation occurs and the status of connections amongst sensors change time to time. One of the major requirements of WBAN is to prolong the network lifetime without compromising on other performance measures, i.e., delay, throughput and bandwidth efficiency. Node prioritization is one of the possible solutions to obtain optimum performance in WBAN. IEEE 802.15.6 CSMA/CA standard splits the nodes with different user priorities based on Contention Window (CW) size. Smaller CW size is assigned to higher priority nodes. This standard helps to reduce delay, however, it is not energy efficient. In this paper, we propose a hybrid node prioritization scheme based on IEEE 802.15.6 CSMA/CA to reduce energy consumption and maximize network lifetime. In this scheme, optimum performance is achieved by node prioritization based on CW size as well as power in respective user priority. Our proposed scheme reduces the average back off time for channel access due to CW based prioritization. Additionally, power based prioritization for a respective user priority helps to minimize required number of retransmissions. Furthermore, we also compare our scheme with IEEE 802.15.6 CSMA/CA standard (CW assisted node prioritization) and power assisted node prioritization under postural mobility in WBAN. Mathematical expressions are derived to determine the accurate analytical model for throughput, delay, bandwidth efficiency, energy consumption and life time for each node prioritization scheme. With the intention of analytical model validation, we have performed the simulations in OMNET++/MIXIM framework. Analytical and simulation results show that our proposed hybrid node prioritization scheme outperforms other node prioritization schemes in terms of average network delay, average throughput, average bandwidth efficiency and network lifetime.
Highlights
Nowadays, smart healthcare services are one of the most preferable demands of our society.A healthcare monitoring service is efficient enough to observe and check a patient anytime and anywhere
For Moderate Priority (MP) nodes of UP3, Contention Window (CW) size is increased as CWMP ∈ [(CWmin− Highest Priority (HP) + 2δ ), 2(CWmin− HP + 2δ )] and CW size of Low Priority (LP) nodes is further increased w.r.t
We have made a comparison of hybrid node prioritization with CW assisted node prioritization, Power assisted node prioritization and unpriortized network on
Summary
Smart healthcare services are one of the most preferable demands of our society. Authors in [10] evaluate the performance of IEEE 802.15.6 based CSMA/CA MAC protocol for stable network with Immediate ACK policy (I-ACK) and without ACK policy on same CW size (without user priority) and derive mathematical expressions for network delay, throughput and bandwidth efficiency. In [11] authors derived analytical expressions for energy consumption of CSMA/CA based contention oriented random access scheme and polling based contention free access scheme, as specified in IEEE 802.15.6 standard They evaluated the performance in terms of network lifetime for both channel access schemes. An amendment to the IEEE 802.15.6 standard has been introduced in [12] using the new Contention Priority (CP) dynamism which is based on the device’s queue length This technique is contributed significantly to achieve optimized throughput, delay and data packet dropping rate.
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