Achievable transmission capacity of cognitive mesh networks with different media access control

Spectrum sharing is an emerging mechanism to resolve the conflict between the spectrum scarcity and the growing demands for the wireless broadband access. In this paper we investigate the achievable transmission capacity of a wireless backhaul mesh network that shares the spectrums of the underutilized cellular uplink over the underlay spectrum sharing model with several commonly adopted medium access control protocols: slotted-ALOHA, CSMA/CA, and TDMA. By employing stochastic geometry, we derive the probabilities for a packet to be successfully transmitted in the primary cellular uplink and the secondary mesh networks. The achievable transmission capacity of the secondary network with outage probability constraints from both the primary and the secondary systems is obtained according to Shannon´s Theory. The capacity region and the achievable capacity when the outage probabilities equal their corresponding threshold values are analyzed numerically and the results illustrate the effect of adjusting the mesh network parameters on the achievable transmission capacity under different MAC protocols.