Capacity analysis of wireless ad hoc networks with improved channel reservation

In ad hoc networks, interference is an important factor limiting the network capacity. Imposing a reservation zone around each receiver has been widely considered to mitigate the interference. A larger reservation zone can decrease the interference, but it also lowers the spatial reuse for reduced simultaneous transmissions. Therefore, there exists an optimal reservation zone to maximize the network capacity. In this paper, rate adaptation is brought to improve the channel reservation scheme, and network capacity achieved by jointly optimizing the data rate and reservation zone is investigated for spread-spectrum (SS) ad hoc networks. Compared to the transmission capacity with fixed data rate assumption, analytical and numerical results show that network capacity can be significantly improved, and the capacity gain remains constant in the order of 300% for direct sequence (DS) SS networks and increases with the growing spreading factors in the range of 300-800% for frequency hopping (FH) SS networks.