Energy Efficiency Scheduling Strategy For Co-existence WBANs

With the growing phenomenon of global aging, telemedicine service gets more andmore attention in recent years. As the core technology of telemedicine service, WirelessBody Area Network (WBAN) becomes one of the hotspot of wireless communicationstechnologies. As a network closely related to user, WBAN is made up of a sensor nodesand a coordinator. Taking into account the special requirements of the medical industryand application convenience, WBAN has strict requirements on volume, transmitterpower, service delay, reliability and so on. Therefore, the performance evaluation ofWBAN includes energy efficiency, throughput, fairness of QoS and so on.As interference is one of the most important factors that affect the performance ofWBAN, the access strategy of MAC layer can greatly reduce the impact of interferenceon WBAN. Access strategy of MAC layer can be divided into contention based andscheduling based, according to channel resource allocation mechanism. Interference inWBAN can be divided in Inter-BAN and Intra-BAN interference, according to thesource of the interference. This paper we focus on the scheduling policy in MAC layerunder the Inter-BAN interference.In this paper we investigate the related researches in the field of static schedulingstrategies. The static scheduling strategy is easy to implement in a centralized networkand can effectively improve the overall performance of the co-existence WBANs. Inthe latest research, the static scheduling strategy based on Horse Racing algorithmperforms well and is easy to apply in the hardware system. In this paper, we study theperformance of Horse Racing algorithm in terms of throughput, energy efficiency andfairness of QoS. In the Two-WBANs scenario, we compare Horse Racing algorithmwith the traversal algorithm. The results of Horse Racing algorithms in terms ofthroughput and energy efficiency can reach80%or more of those in traversal algorithm.However, both of them have significant deficiencies in terms of fairness of QoS. Thelack of fairness is a common problem of static scheduling strategies. The reason is thatonce the scheduling strategy is determined, the quality of the slots allocated to eachnode is determined, and therefore there is no chance to make the balance. Consider of the problems of static scheduling strategy mentioned above, we designthe dynamic scheduling strategy to improve the fairness performance. To facilitate theresearch, we make the assumptions that each WBAN access channel concurrently, andeach node access channel once or less in one superframe. We establish thecommunication model based on the above assumptions, and design the dynamicscheduling strategies based on throughput maximization and energy efficiencymaximization respective. The optimization problems for them belong to the0-1programming problems, and the only way to find the optimal solution is by traversingall the possible conditions. As the statistic value of fairness is considered in theoptimization problems, we designed Fairness-based Throughput MaximizationHeuristic (FTMH) algorithm and Fairness-based Energy Efficiency Maximization(FEEM) algorithm to find the suboptimal solutions. The results of the FTMH andFEEM show that compared with the static scheduling strategy, dynamic schedulingstrategy performs better in terms of fairness. In the condition of strong interference,FEEM get better performance than FTMH.As polling method is used in designing the dynamic scheduling strategy, in practicalapplication, each WBAN system can optimize its own strategy separately based on theinterference information collected by control center. Along with the prolonged of theoperation time, the system performance tends to the optimal value.