text: We focus on interference mitigation and energy conservation within a single wireless body area network (WBAN). We adopt two-hop communication scheme supported by the the IEEE 802.15.6 standard (2012). In this paper, we propose a dynamic channel allocation scheme, namely DCAIM to mitigate node-level interference amongst the coexisting regions of a WBAN. At the time, the sensors are in the radius communication of a relay, they form a relay region (RG) coordinated by that relay using time division multiple access (TDMA). In the proposed scheme, each RG creates a table consisting of interfering sensors which it broadcasts to its neighboring sensors. This broadcast allows each pair of RGs to create an interference set (IS). Thus, the members of IS are assigned orthogonal sub-channels whereas other sonsors that do not belong to IS can transmit using the same time slots. Experimental results show that our proposal mitigates node-level interference and improves node and WBAN energy savings. These results are then compared to the results of other schemes. As a result, our scheme outperforms in all cases. Node-level signal to interference and noise ratio (SINR) improved by 11dB whilst, the energy consumption decreased significantly. We further present a probabilistic method and analytically show the outage probability can be effectively reduced to the minimal.
  @cite_14: 
  @cite_4: In this paper, a cooperative two-hop communication scheme, together with opportunistic relaying (OR), is applied within a mobile wireless body area network (WBAN). Its effectiveness in interference mitigation is investigated in a scenario where there are multiple closely-located networks. Due to a typical WBAN's nature, no coordination is used among different WBANs. A suitable time-division-multiple-access (TDMA) scheme is adopted as both an intra-network and also an internetwork access scheme. Extensive on-body and off-body channel gain measurements are employed to gauge performance, which are overlaid to simulate a realistic WBAN working environment. It is found that opportunistic relaying is able to improve the signal-to-interference-plus-noise ratio (SINR) performance at an outage probability of 10 by an average of 5 dB, and it is also shown that it can reduce level crossing rate (LCR) significantly at low SINRs. Furthermore, this scheme is more efficient when on-body channels fade more rapidly.
  @cite_10: 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.
  @cite_3: This paper investigates the issue of interference mitigation in wireless body area networks (BANs). Although several approaches have been proposed in BAN standard IEEE 802.15.6, they increase transmission latency or energy cost, and do not mitigate interference effectively. In order to avoid both intra- and inter-BAN interference, we present a MAC protocol with two-layer interference mitigation (2L-MAC) for BANs. Considering the QoS requirements of BANs, the proposed protocol not only avoids packet collisions but also reduces transmission delay and energy consumption in sensors. Moreover, channel switching is triggered whenever a BAN needs to acquire more bandwidth. Simulation results show that our protocol outperforms other protocols in terms of delivery rate, latency and energy saving.
  @cite_2: This paper focuses on the energy efficiency of communication in small-scale sensor networks experiencing high path loss. In particular, a sensor network on the human body or BASN is considered. The energy consumption or network lifetime of a single-hop network and a multi-hop network are compared. We derive a propagation model and a radio model for communication along the human body. Using these models, energy efficiency was studied analytically for a line and a tree topology. Calculations show that single-hop communication is inefficient, especially for nodes far away from the sink. There however, multi-hop proves to be more efficient but closer to the sink hotspots arise. Based on these findings, we propose to exploit the performance difference by either introducing extra nodes in the network, i.e. dedicated relay devices, or by using a cooperative approach or by a combination of both. We show that these solutions increase the network lifetime significantly.
  @cite_5: 
  @cite_13: We study the use of wireless relay channel in a one-hop sensor network with random packet arrival. Exploiting regular sensor nodes to serve in a wireless relay channel can increase the overall network capacity. However, due to asynchronous source transmission, the relays interfere with each other's transmission and reception. The fundamental trade-off between these two issues leads us to an optimization problem in which we find the optimum relay zone radius to maximize the overall sum rate of the network. We also propose a MAC protocol to choose the optimum number of sources allowed to transmit under this setting. The overall system capacity is proven to increase significantly under the proposed scheme, compared with cases where relay nodes are not exploited or where the relay zone radius is suboptimal
summary: Recent studies show multi-hop scheme has a lower power consumption in comparison to one-hop scheme. Using relays reduces the whole WBAN interference and its power consumption @cite_4 @cite_13 @cite_2 . On the other hand, other works prove that TDMA scheme is an attractive solution to avoid interference within an intra-WBAN. These schemes require time synchronization which is infeasible when large number of WBANs coexist @cite_10 @cite_3 @cite_14 . Some efforts focus on co-channel interference analysis of non-overlapping WBANs. They develop a model for efficient network planning and resource management by using geometrical probability approach @cite_5 . Other research works assume one desired and multiple coexisting interferers WBANs. The coordinator of the desired WBAN calculates SINR periodically and afterwards commands its nodes to select an appropriate interferece mitigation scheme @cite_10 .