On gain asymmetry and broadcast efficiency in MIMO ad hoc networks

In this paper, the problem of broadcast in ad hoc networks with smart antennas in a general propagation scenario is investigated. The conventional models proposed in the literature are surveyed and their limiting assumptions on the array at the receiver are identified. The connection between this point and the gain asymmetry for the broadcast of control packets is explored. As a first result, the impossibility to solve this problem in a conventional setting is proved. Then, a solution is mathematically deduced based on the consideration that a true MIMO (rather than MISO) system is required. The scheme can simultaneously send these packets farther, omnidirectionally and with very limited delay. Finally, a comparison with the Circular RTS scheme [1] is carried out with interesting results.