In this paper, we investigate the network throughput achieved by both spatial diversity and spatial frequency reuse in a wireless ad hoc network with randomly positioned single-hop source-destination pairs and relays. Compared with conventional direct transmissions, cooperative communication can enhance single-link transmission reliability but reduce network-wide spatial frequency reuse due to relay transmissions. To study the tradeoff between these two competing effects, we construct a geographically constrained region for relay selection based on channel state information.
The network throughput, defined as the product of the success probability of each link and the expected number of concurrent transmissions, is derived as a function of the total number of links, relay density, size of relay selection region, and distance between the source and destination. The performance analysis is carried out for both selection combining and maximum ratio combining at the destination. Such analytical results can evaluate the effectiveness of cooperative communication and provide useful insights on the design of large-scale networks. Finally, extensive simulations are conducted to validate the performance analysis.