Backward-Compatible Dynamic Spectrum Leasing for 802.11-Based Wireless Networks

Dynamic spectrum access (DSA) is proposed to deal with the growing shortage of available leased spectrum for wireless communication. We investigate a subset of DSA referred to as Dynamic Spectrum Leasing (DSL). At its core, DSL allows spectrum lease holders and cognitive radios to cooperate in an effort to leverage spatial diversity to improve channel utilization for both parties. In this research, cognitive radios offer their services as an intermediate relay node in an effort to improve throughput of primary users utilizing a 802.11-based channel access mechanism. In return, the cognitive radio ´piggy-backs´ some of its own data while acting as a relay. In this paper, a simple coordination scheme is introduced that allows a network of Secondary Users to coordinate with a Primary User network´s access point. This scheme does not require any modification to the primary users´ 802.11-based protocol stack as our protocol is implemented only at the access point and the secondary users. Analytical insights into the overhead required for this coordination and the optimization of the overhead are presented. It is shown that, given sufficient relay channel conditions, forwarding packets through a secondary relay channel can be beneficial to both parties in terms of saturation throughput.