Secondary transmission profile for a single-band cognitive interference channel

In this paper, we model a cognitive interference channel with two flows, a primary and a secondary. The primary traffic is bursty which gives rise to idle channel periods in time. The objective for the secondary flow is to utilize the temporal white spaces and to maximize its own rate without adversely affecting the primary flow's SINR beyond a given threshold. The key aspect analyzed in this paper is the lack of knowledge about start and stop times of primary flow's transmissions. We propose a sense-and-send protocol where the secondary senses to detect idle channels and then divide its transmissions into many small bursts (making it paranoid about overlapping on primary's transmissions). Furthermore, since the secondary cannot sense while transmitting (assuming half-duplex radios), it has to reduce its transmission power for each subsequent symbol in each component burst. Thus, the proposed power profile for the secondary is significantly different from that in a regular interference channel, where both flows have the same "status."