Connectivity and Scaling Behavior of Power-limited Directional Infrastructureless Wireless Networks

This paper identifies regimes of high connectivity and the associated throughput, delay, and energy per bit scaling performance of a power-limited infrastructureless wireless network. Infrastructureless wireless networks are a key strategic technology for future military communications. In their current state, their utility for mission critical applications is limited by their susceptibility to disconnection. However, the inclusion of directional antennas increases communication range for a given transmit power and path loss characteristic and hence improves network connectivity. Previous work on the benefits of directional infrastructureless wireless networks considered interference-limited systems. We analyze the connectivity benefits of directional antennas when used in power-limited networks (networks where there is sufficient bandwidth available to avoid interference effects). We characterize the level of directionality required to achieve a desired probability of connectivity under given operating conditions, and we find that end-user density can decrease significantly while maintaining a high probability of connectivity. We also consider how the performance benefits of directional antennas are affected by scaling the end-user density in a fixed-size operating region. This scaling behavior analysis demonstrates the existence of routing schemes with Theta(1) hops that achieve the optimal Theta(1) throughput, delay, and energy consumption per bit scaling behavior.