Impact of exclusion region and spreading in spectrum-sharing ad hoc networks

In wireless ad hoc network medium access control (MAC) protocol design, it is important to incorporate an exclusion region around a receiver, such that nodes inside the exclusion region are not allowed to transmit, to limit the interference caused to the receiver. In this paper, we investigate the performance trends of a spread-spectrum-based network with respect to outage constraints and derive its relationship with the size of the exclusion region and the spreading factor. A non-spread-spectrum-based network is a special case with a spreading factor of one. We show that there exists an optimal size for the exclusion region with respect to maximizing the performance of the network which depends upon the spreading factor used in the network. It is also shown that the throughput of the network degrades while the throughput of individual users improves with an increase in spreading factor. These results are used to show that spectrum-sharing (SS) schemes based on interference-avoidance are desirable from a network performance perspective while interference-averaging-based SS schemes are desirable from the perspective of the performance of individual users.