2009/08/17 by Makesh Pravin Wilson, Wilson, Makesh Pravin, Krishna R. Narayanan +2
Computer Science · Engineering · Mathematics · #Cooperative Communication and Network Coding #FOS: Computer and information sciences #Full-Duplex Wireless Communications #Information Theory (cs.IT) #Wireless Communication Security Techniques #cs.IT #math.IT
paper · pdf · doi:10.48550/arxiv.0908.2408
5 pages, 4 figures and was presented at the International Symposium on Information Theory - ISIT 2009
arxiv created 2009/08/17 · openalex publication_date 2009/08/17 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We consider a communication system where two transmitters wish to exchange information through a half-duplex relay in the middle. The channels between the transmitters and the relay have asymmetric channel gains. More specifically, the channels are assumed to be synchronized with complex inputs and complex fading coefficients with an average power constraint on the inputs to the channels. The noise at the receivers have the same power spectral density and are assumed to be white and Gaussian. We restrict our attention to transmission schemes where information from the two nodes are simultaneously sent to the relay during a medium access phase followed by a broadcast phase where the relay broadcasts information to both the nodes. An upper bound on the capacity for the two phase protocol under a sum power constraint on the transmit power from all the nodes is obtained as a solution to a convex optimization problem. We show that a scheme using channel inversion with lattice decoding can obtain a rate a small constant 0.09 bits from the upper bound at high signal-to-noise ratios. Numerical results show that the proposed scheme can perform very close to the upper bound.