Non-Coherent Hierarchical Cooperation

Hierarchical cooperation is a communication strategy introduced recently by Ozgur et al. and shown to significantly outperform standard multi-hop communication in some wireless scenarios. To achieve this gain over multi-hop communication, full availability of channel state information at all the nodes in the network is required. In this paper, we investigate the impact of absence of channel state information on the performance of hierarchical cooperation. If the product of coherence time and coherence bandwidth of the wireless channel is on the order of the number of nodes in the network, we show that non-coherent hierarchical cooperation achieves the same order rate as the coherent version. If the product is smaller than the number of nodes, we show that non-coherent hierarchical cooperation can still yield sizable gains over multi- hop communication, but may not achieve the same order rate as the coherent version.