An Energy-efficient Multi-channel MAC Protocol Research For WBAN

Along with the continuous increase of elderly population in most countries and the advance of modern technology,people's urge for advanced and considerate medical service increases greatly.More people are favor of modern remote medical services.In recent years,Wireless Body Area Network(WBAN)becomes the core technology of modern medical system which comprises in-body or around-body sensor nodes for collecting data of physiological feature.WBAN offers users with intelligent personalized healthcare services and entertainment applications as well,which shows a broad development prospects.WBAN is so widely used that the IEEE published an international standard IEEE 802.15.6.It contains comprehensive technical guidance of medium access control(MAC),physical layer(PHY)and security service which provides powerful foundation for WBAN designers.This thesis studies standard IEEE 802.15.6 and designs an energy-delay efficient MAC protocol named ED-MAC dedicated to WBAN.In addition,this thesis evaluates the network access performance of IEEE 802.15.6 and ED-MAC protocol through theoretical analysis.Both of the theoretical analysis results prove ED-MAC outperforms IEEE 802.15.6.Many elements can affect the performance of WBAN and interference plays an important role involving the network service.Open wireless environment brings other interferences to WBAN,such as the influence from Wi Fi.The failure of transmission due to interference will expend extra energy as well as reduce the reliability and security thus it should not be ignored.Multi-channel scheme,in which different devices can transmit data in parallel channels,is shown as a promising way to reduce interference by avoiding using the same frequency.However,traditional multi-channel protocols in WSN(Wireless Sensor Networks)and Ad hoc are not suitable for WBAN for its nature characteristics and special medical application scenario.Considering the application characteristics and business requirements,this thesis proposes a multi-channel protocol ED-MAC.Our main contributions are presented as follows: 1.A novel one-to-one channel mapping mechanism between channel state field and multiple channels is proposed.2.Considering theunfairness between high and low priorities,we propose channel selection and selection conflict avoidance mechanisms.3.We evaluate the network performance in terms of traffic arrival rate and number of nodes and simulation results show that the performances can be promoted obviously.In addition,nodes in WBAN have higher requirements of energy consumption for their restricted of size and power.Contention-based access to the media is one of the main access methods and WBAN can use CSMA/CA mechanism to access to the channel.This thesis proposes to analyze the CSMA/CA mechanism in IEEE 802.15.6 and ED-MAC protocol.The simulation about normalized throughput and delay proves that under high traffic loads,IEEE 802.15.6 CSMA/CA mechanism utilizes the wireless medium poorly.The analysis results show the introduction of multi-channel technology can mitigate the poor performance of the contention based access mechanism.Compared with single channel protocol,this proposed multi-channel protocol ED-MAC outperforms in view of network throughput,delay and energy consumption.