Addressing the Hidden Incumbent Problem in 802.22 Networks

In the context of IEEE 802.22 networks, the hidden incumbent problem refers to a situation in which a consumer premise equipment (CPE) is within the protection region of an operating incumbent but it fails to report the existence of the incumbent to its base station (BS). In such a scenario, CPEs within the incumbent’s transmission range may not be able to decode the BS signal because of the strong interference from the incumbent signal. Moreover, the CPEs cannot report the existence of the incumbent as their transmission will cause interference to the incumbent. Therefore, these CPEs are unable to report the existence of the incumbent to the BS, and hence the BS fails to detect the presence of the incumbent. To address this problem, IEEE 802.22 prescribes that the BS broadcasts explicit outband control signals on a set of candidate channels and CPEs search for control signals on those candidate channels so that they can send the hidden incumbent detection messages to the BS via one of the candidate channels. In this paper, we present a systematic way of designating the candidate channel sets for the hidden incumbent detection (HID) protocol in 802.22 networks. The proposed approach has two noteworthy features: (1) it allows the BS and the CPE to choose different sets of candidate channels in a distributed manner without message exchanges; and (2) it significantly reduces the size of the set of candidate channels for each 802.22 entity, thus lowering the control overhead of the HID protocol.