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A Wireless Body Area Networks (WBAN) is a communication network that provides both medical and consumer electronics (CE) services by using sensor devices in, on, or around a human body. To provide reliable communication with low power consumption for in-body communication, the IEEE 802.15.6 provides Medical Implant Communication Service (MICS) band and defines its communication policy. However, MICS band communication suffer from the coexistence problem, which causes significant performance degradation due to high-density deployment and network-level mobility of WBANs. In addition, existing coexistence mitigation schemes in IEEE 802.15.6 do not consider the MICS band. To overcome the coexistence problem, numerous studies have been conducted for multi-channel usage in WBANs, but they just include simple channel selection schemes which do not provide reliable channel selection. This paper proposes an Adaptive Channel Estimation and Selection Scheme (ACESS) for coexistence mitigation in WBANs. The proposed method maintains a history table and predicts the conditions of available channels based on two-state Markov chain with an exponentially controlled channel history, which can control the sensitivity of prediction. Our simulation study show that the proposed scheme can improve communication performance in terms of Packet Reception Ratio (PRR) under coexistence environments with multiple WBANs.

A Wireless Body Area Network (WBAN) which consists of wireless sensors in/on/around human body requires high reliability for medical data. The coexistence problem which occurs when multiple-WBANs occupy the same channel at the same time declines the performance of the network. It is an important issue because this problem causes the collision of data among WBANs. For that reason, the IEEE 802.15.6 which was established for WBAN standardization defined guidelines to solve this problem, but these guidelines did not provide detailed methods. To solve this problem, there are also a few related works by using graph coloring algorithm as a general theory to assign limited resources but they cannot satisfy the requirements of WBAN. In this paper, we propose a distributed multi-coloring algorithm to mitigate coexistence problems among WBANs. The proposed algorithm shows short transmission-cycle per WBAN through multiple coloring with a color sequence and the efficiency of the proposed scheme is verified by the numerical results which outperform existing works in multiple WBANs environment.

Wireless body area networks (WBANs) which is standardized by IEEE 802.15 TG6 support communication service with in/on/around body. Similar to wireless sensor network (WSN) environment, devices of WBAN may be densely deployed. Compared with WSN, however, WBAN operates in a centralized manner, and thus, contention complexity on contention-based phase of WBAN may be larger than WSN. In this paper, we propose a novel channel access algorithm for contention based MAC protocol in WBANs. The proposed algorithm classifies the contention-based access phase into 4-levels by the priority of packet that is defined in WBAN draft document, and divides the contention-based access phase into sub-period by calculated offset. Extensive simulation results show that the proposed algorithm achieves low complexity such as reduced collisions, low power consumption, and high channel utilization compared with the IEEE 802.15.6 baseline MAC protocol.