Information theoretic aspects of constrained cell-sites cooperation

We review some recent information theoretic results on cooperation in cellular systems, addressing multicell processing (cooperation among base stations) and relaying (cooperation at the user level). This talk will focus on the information theoretic implications of practical assumptions of limited capacity links and constrained interbase station cooperation. First multicell processing is studied with either limited-capacity backhaul links to a central processor or only local (and finite-capacity) cooperation among neighboring cells. Clustered based multi-cell decoding is also considered. The role of codebook information, with emphasis on structured codes, decoding delay and network planning (frequency reuse) are specifically highlighted along with the impact of different transmission/reception strategies. We shall address non-fading and fading uplink and downlink channels adhering to simple Wyner type, cellular system models. The analytical treatment enhances the insight into the limitations imposed by practical constraints on the potential gains associated with cooperative techniques. In particular, achievable rates are compared with upper bounds and analyzed in asymptotic regimes, deriving the conditions under which certain techniques are optimal. The talk is based on numerous joint studies with O. Simeone, M. Gastpar, A. Lapidot, N. Levy, B. Nazer, V. Poor, A. Sanderovich, O. Somekh, M. Wigger and B. Zaidel.