  Wireless local area networks (WLAN) still suffer from a severe performance
discrepancy between different users in the uplink. This is because of the
spatially varying channel conditions provided by the wireless medium.
Cooperative medium access control (MAC) protocols as for example CoopMAC were
proposed to mitigate this problem. In this work, it is shown that cooperation
implies for cooperating nodes a tradeoff between throughput and bit-cost, which
is the energy needed to transmit one bit. The tradeoff depends on the degree of
cooperation. For carrier sense multiple access (CSMA) based networks, the
throughput/bit-cost tradeoff curve is theoretically derived. A new distributed
CSMA protocol called fairMAC is proposed and it is theoretically shown that
fairMAC can asymptotically achieve any operating point on the tradeoff curve
when the packet lengths go to infinity. The theoretical results are validated
through Monte Carlo simulations.
