Capacity scavenging in wireless networks: A comparative study

Dynamic spectrum access can enable secondary network users to access unused spectrum, or whitespace, which is found between the transmissions of primary users in a wireless network. The main design objectives for secondary user access strategy are to be able to ¿scavenge¿ spatio-temporally fragmented whitespace opportunities while limiting the amount of interference caused to the primary users. In this paper, we propose a novel secondary user access strategy which is based on measurement and modeling of the whitespace as perceived by the secondary network users. A secondary user continually monitors its surrounding whitespace, models it, and then attempts to access the available spectrum holes so that the effective secondary throughput is maximized while the resulting interference to the primary users is limited to a pre-defined bound. We first develop analytical expressions for the secondary throughput and primary interference, and then perform ns2 based simulation experiments to validate the effectiveness of the proposed access strategy, and evaluate its performance against two other access schemes from the cognitive network literature.