Formulating multilateral trade-off of sensing, missed idle and transmission times in dynamic spectrum access networks

many studies have been done in cognitive radios to maximize the network efficiency. The efficiency is usually defined in the form of throughput, energy efficiency or spectrum efficiency. With the advent of dynamic spectrum access concept in wireless networks, efficiency in such networks must be defined in order to best consider all the important metrics involved. For example, many works in cognitive radio network (CRN) neglect the interference due to primary user returns to the frequency band, and moreover; nobody has considered missed idle times during waiting throughout the entire current frame when the channel is sensed busy at the beginning. Both mentioned interference and missed opportunities depend on primary user traffic characteristics, secondary network communication protocol, sensing time and transmission time. Clearly, to consider them, we define and formulate a new efficiency metric in network dynamic access strategy called Access Efficiency in order to consider both interference, sensing time and missed opportunities due to transmission and waiting times respectively. Then, the optimized values for sensing and transmission time are computed using genetic algorithm in order to maximize Access Efficiency. The optimization point concurrently reduces missed idle times and maximizes successful transmission times (conventional throughput). It is obvious that a network protocol with higher Access Efficiency misses less idle times and imposes less collision on users.