Distributed orthogonalization in large interference relay networks


Veniamin I. Morgenshtern, Helmut Bölcskei, and Rohit U. Nabar


Proc. IEEE Int. Symposium on Information Theory (ISIT), Adelaide, Australia, pp. 1211-1215, Sept. 2005.

DOI: 10.1109/ISIT.2005.1523534

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We study fading interference relay networks where M single-antenna source-destination terminal pairs communicate through a set of K relays using half-duplex two-hop relaying. Two specific protocols are considered, P1 introduced in [Bölcskei et al., 2004] and P2 introduced in [Dana and Hassibi, 2003]. P1 relies on the idea of relay partitioning and requires each relay terminal to know one backward and one forward fading coefficient only. P2 requires each relay terminal to know all M backward and M forward fading coefficients and does not need relay partitioning. We prove that in the large-M limit the minimum rate of growth of K for P1 to achieve a strictly positive per source-destination terminal pair capacity is K~M^3 whereas in P2 it is K~M^2. The protocols P1 and P2 are thus found to trade off the number of relay terminals for channel state information (CSI) at the relays; more CSI at the relays reduces the total number of relays needed to achieve a strictly positive per source-destination terminal pair capacity in the large-M limit.


Relay networks, capacity scaling, distributed orthogonalization


Compared to the version in the proceedings, minor corrections in the formulation of Theorems 1 and 2.

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