Relay node selection in Two Hop Extended Star Topology based Wireless Body Area Network

Abstract

A Wireless Body Area Network (WBAN) is a special purpose sensor network designed to operate autonomously to connect various medical sensors and appliances, located inside and outside the human body. These medical sensors are capable of measuring, processing, and forwarding important physiological parameters. To facilitate the development of WBAN, IEEE 802.15.6 Task Group 6 (TG6) that released IEEE 802.15.6 standard in 2012. The standard provide physical and medium access for wireless BAN. IEEE 802.15.6 creates star topology based network that is established and maintained by central device preferred as hub. An important aspect of the standard is that it can support two hop extend star topology. The aforementioned topology is created using relay node. The multi-hop (two hop) topology is especially useful for extremely low power in-body and around-body implanted devices that can decrease energy consumption by transmitting to hub through near-by relay node(s). IEEE 802.15.6 define the message exchange necessary for the announcement and selection of relaying node. However, the standard does not define the metrics based on which the relayed node should select the relaying nodes. In this thesis we propose and use packet drop, packet service time and packet retries as the basic metrics for the selection of relaying node. Also, another novelty of this work is that the decision of node selection is mode by the relayed node based on the feedback provided by relaying node. On the other hand, IEEE 802.15.6 suggests that the decision should be made by relayed node without the involvement of relaying nodes. Detailed simulation analysis using OPNET is conducted in this thesis which reveals that the relaying node selection based on the feedback of different metrics results in better throughput and low latency of communication.