Channel capacity in fading environment with CSI and interference power constraints for cognitive radio communication system

Capacity in fading environment based on soft sensing information under spectrum sharing constraints

“…In [19], ergodic capacity for Nakagami fading channel is investigated based on sensing statistics and CSI of secondary link under average interference constraint with no peak power restriction of secondary user. However, the secondary user transmission power must be limited within the operating range of power amplifier and to avoid health endangering situation.…”

“…In fading environment, following same line of development as in [19], it is straightforward to show that channel capacity can be achieved with optimum power distribution such that both the constraints are satisfied. Assuming Y s and Y sp are independent to each other, the channel capacity becomes the solution of the following optimization problem …”

“…Depending upon channel inversion 1 Y s , power adaptation scheme is divided into three parts with respect to two (19), it can be observed that unlike [19] transmission is limited to peak value when channel inversion is weaker than Y v n ð Þ N 0 B . In other words, from (17) and (19) it is clear that, when fading between secondary transmitter and primary and secondary receivers is deep, STx can transmit with maximum power i.e.…”

“…In other words, from (17) and (19) it is clear that, when fading between secondary transmitter and primary and secondary receivers is deep, STx can transmit with maximum power i.e. P Peak : The second part represents the optimum transmission…”

“…However, in [17,18] different system capacities have been assessed for secondary user without using soft sensing information. In [19], ergodic capacity under Nakagami-m fading channel is investigated based on sensing parameter and CSI of secondary link under average interference power constraint whereas, peak transmission power of secondary user is ignored which results ergodic capacity to increase monotonically. However, to avoid health endangering situation and to restrict the secondary transmission power within the operating range of power amplifier, it is important to restrict secondary user transmission power with peak power constraint.…”