  When sensors of different coexisting wireless body area networks (WBANs)
transmit at the same time using the same channel, a co-channel interference is
experienced and hence the performance of the involved WBANs may be degraded. In
this paper, we exploit the 16 channels available in the 2.4 GHz international
band of ZIGBEE, and propose a distributed scheme that avoids interference
through predictable channel hopping based on Latin rectangles, namely, CHIM. In
the proposed CHIM scheme, each WBAN's coordinator picks a Latin rectangle whose
rows are ZIGBEE channels and columns are sensor IDs. Based on the Latin
rectangle of the individual WBAN, each sensor is allocated a backup time-slot
and a channel to use if it experiences interference such that collisions among
different transmissions of coexisting WBANs are minimized. We further present a
mathematical analysis that derives the collision probability of each sensor's
transmission in the network. In addition, the efficiency of CHIM in terms of
transmission delay and energy consumption minimization are validated by
simulations.
