  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.
