Cost of Path Loss and Local Cooperation in Capacity Scaling of Extended Wireless Networks

Given a large wireless network consisting of randomly deployed nodes, where each of the nodes wants to transmit to a random destination node within the network at some equal rate, how fast can the sum rate grow as the number of nodes scales up at fixed density? This question is important because it captures the bottleneck of message exchanging among randomly deployed Internet-of-Things (IoT) devices, and it models nicely the wireless backhaul communication among access points or within airborne communication systems. Previous work has shown that, given an extended network with fixed density, multi-hop routing based approach provides sum rate that scales at most as the square root of network size, where as hierarchical cooperation protocols have the potential to support linear scaling. With limited power, the SNR decreases at least inverse proportional to the network size, and therefore the benefit of hierarchical cooperation will be curbed by the combined effects of path loss and local communication cost. We show in this paper how the path loss and local cooperation cost reshape the capacity scaling law results.