Impact of power control on network-layer stability in cognitive radio systems

In cognitive radio (CR) systems, secondary transmitters (STs) should have etiquette that its transmission is not harmful to primary communication. Limiting transmitting power of ST is a usual way of being polite in a physical-layer point of view. In this paper, we assume that a primary user (PU) has a desire to keep its stable throughput though ST intervenes, which is a network-layer goal. And we investigate how the physical-layer tool of power control manages to keep the network-layer requirement in CR systems by assuming different levels of channel knowledge. We provide secondary power allocation strategies according to the channel knowledge, which does not violate PU's desire. Numerical investigation is used to show where and how much the proposed power allocation is effective.