Capacity of power constrained ad-hoc networks

Throughput capacity is a critical parameter for the design and evaluation of ad-hoc wireless networks. Consider n identical randomly located nodes, on a unit area, forming an ad-hoc wireless network. Assuming a fixed per node transmission capability of T hits per second at a fixed range, it has been shown that the uniform throughput capacity per node r(n) is ⊗(T/√nlogn). We consider an alternate communication model, with each node constrained to a maximum transmit power P₀ and capable of utilizing W Hz of bandwidth. Under the limiting case W→∞, such as in ultra wide band networks, the uniform throughput per node is ⊗((nlogn)^α-12/ (upper bound) and Ω(n^(α-1)2//(logn)^(α+1)2/) (achievable lower bound). These bounds demonstrate that throughput increases with node density n, in contrast to previously published results. This is the result of the large bandwidth, and the assumed power and rate adaptation, which alleviate interference. Thus, the significance of physical layer properties on the capacity of ad-hoc wireless networks is demonstrated.