Study Of Energy Efficient Wban Topology In IEEE 802.15.6

In the last few decades, we have witnessed a steady increase in many parts of the world, leading to a sharp rise in the number of elderly people. A recent report from United Nations predicted that the world will have twenty billion elderly people, accounting for 22% of the world’s population by 2050. In addition, research indicates that about 89% of the aged people are likely to live independently. However, medical research surveys found that about 80% of the aged people older than 65 suffers from at least one chronic disease, causing many aged people to have difficulty in taking care of themselves.Therefore, providing a decent and quality life for aged people has become a serious social challenge. Recently, human health monitoring is an emerging technology. As a typical representative, wireless body area network (WBAN) mainly use the cooperation of microelectronics, wireless communications, integrated circuits and sensor technology. WBAN is composed of several body sensors and the sink node. These body sensors are capable of sensing and processing the body signals (such as SPO2, skin temperature, etc) and the sink node is responsible for communicating with remote human health monitoring. In WBAN, body nodes are either worn on a human body or small enough to be implanted in body. Because the energy of sensor nodes is limited, so the paper mainly carried out a research on the design and optimization of topology structure in order to save energy and extend the life cycle.In this paper, an optimization model is proposed to design the network topology of wireless body area network (WBAN). Focusing on the two hops extended star topology given in IEEE802.15.6 standard, a mixed integer non linear programming model is constructed to minimize the energy consumption of WBAN. Then, the optimized network topology is obtained by adjusting the number and location of relays to be deployed and the data routing towards the hub. The experimental results show that, compared with Elias’s model(energy aware WBAN design, EAWD), the proposed model can reduce network energy consumption by 40.5%, decrease network delay by 52.4% on average, and extend network lifetime by double.Long time monitoring for wireless body area network is one of the most important requirements, so we put forward a topology control method, relay nodes reselection strategy based on awakening process, when the sink node identify that the energy consumption of a relay node reaches the threshold, the strategy begin running, it looks up all the relay nodes, and compares their residual energy and the distance of the sensor, then selects the most close and the more remaining energy relay nodes; If there is no right choice or the distance of candidate relay node is greater than the distance of sink node, then the sensor nodes will communicate directly with the sink. The experimental results show that, the lifetime of sensor nodes increase by 22.6% on average and network lifetime increase by 37.5％.