A Fully-Distributed PHY/MAC for High Capacity Mobile Ad Hoc Networks: Robust Interference Alignment

Interference Alignment (IA) has emerged as a promising technique to improve the capacity of future wireless networks. In IA, radio terminals with multiple antennas co-optimize, or align their transmitter and receiver antennas within a group (or cluster) of users, to suppress or eliminate interference within the cluster. We propose a unique slotted MAC structure that uses Zadoff-Chu sequences to distinguish user transmissions during the alignment. Users are able to simultaneously update their antennas weights, avoiding inefficient contention-based mechanisms to assign slots. We use a unique antenna algorithm, the Minimum Interference Leakage Beamformer (MIL-B) as our starting point. Simulations show MIL-B gives an amazing 4x gain over a standard MIMO system sending to one user at a time (TDMA). Our MAC design is fully distributed, yet is able to incorporate mechanisms for user selection, fairness, and synchronization.