In this paper, we propose a distributed multi-hop interference avoidance algorithm, namely, IAA to avoid co-channel interference inside a wireless body area network (WBAN). Our proposal adopts carrier sense multiple access with collision avoidance (CSMA CA) between sources and relays and a flexible time division multiple access (FTDMA) between relays and coordinator. The proposed scheme enables low interfering nodes to transmit their messages using base channel. Depending on suitable situations, high interfering nodes double their contention windows (CW) and probably use switched orthogonal channel. Simulation results show that proposed scheme has far better minimum SINR (12dB improvement) and longer energy lifetime than other schemes (power control and opportunistic relaying). Additionally, we validate our proposal in a theoretical analysis and also propose a probabilistic approach to prove the outage probability can be effectively reduced to the minimal.
Other research focuses on the performance at the coordinator that calculates SINR periodically. This calculation enables C to command its nodes to select appropriate interferece mitigation scheme @cite_11 . Other studies of @cite_10 analyze the performance of a reference WBAN. They evaluate the performance in terms of bit error rate, throughput and lifetime which have been improved by adoption of an optimized time hopping code assignment strategy. Works in @cite_4 consider a WBAN where coordinator periodically queries sensors to transmit data. The network adopts the CSMA CA and the nodes adopt link adaptation to select the modulation scheme according to the experienced channel quality.
@cite_10 @cite_4 @cite_11
2032297769 2035002549 2073051949
A Wireless Body Area Network (WBAN) consists of different tiny physiological wearable sensors to monitor the vital signs of a human body and these sensor nodes transmit in real-time the sensed physiological information to the on-body coordinator or server over a wireless medium. Any radio frequency based wireless device suffers from interference due to the existence of other wireless devices operating in the same frequency band. In this paper we address the problem of interference when multiple WBANs come in the proximity of one another. We propose a TDMA-based solution that creates a common schedule between these WBANs, so that there is seamless communication with their sensors without interference among them, while increasing the cost of latency per node. Also, when these TDMA based WBANs come in the close proximity of one another, they sense the existence of other interfering WBANs. Our solution proposed a scheme that defines the time when to exchange their TDMA schedules. We simulated the proposed solution using NS-3 network simulator and it is observed that there is improvement in the percentage of packet delivery by using the proposed scheme. It is also observed that the increase of speed of WBANs leads to decrease in the percentage of packet delivery. In this paper we consider an IEEE 802.15.4-based Wireless Body Area Network, where wearable sensor devices are distributed on a body and have to send the measured data to a coordinator. The Carrier Sense Multiple Access with Collision Avoidance algorithm defined by the standard is used as Medium Access Control protocol, whereas different modulation schemes are assumed to be available at the physical layer. We propose a novel Link Adaptation (LA) strategy, where nodes select the modulation scheme according to the experienced channel quality and level of interference. The novelty lays in the fact that in case of large Signal-to-Noise Ratio and low Signal-to-Interference Ratio nodes increase the bit rate, instead of reducing it, as largely done in the works present in the literature. The reduction of the bit rate, in fact, allows to decrease the time the channel is occupied and, therefore, the collision probability. Performance is evaluated in terms of packet error rate and results achieved with and without LA are compared. Results show that the proposed strategy improves performance. Considering the medical nature of the information carried in body area networks (BANs), interference from coexisting wireless networks or even other nearby BANs could create serious problems on their operational reliability. As practical implementation of power control mechanisms could be very challenging, link adaptation schemes can be an efficient alternative to preserve link quality while allowing more number of nodes to operate simultaneously. This paper proposes several interference mitigation schemes such as adaptive modulation as well as adaptive data rate and duty cycle for BANs. Interference mitigation factor is introduced as a measure to quantify the effectiveness of the proposed schemes. These schemes are relatively simple and well-suited for low power nodes in BANs that might be operating in environments with high level of interference.