Bit-additive superposition coding for the bandwidth limited broadcast channel

• Published in: Proceedings / IEEE International Symposium on Information Theory pp. 165 - 169
• Main Authors: Abotabl, Ahmed Attia, Nosratinia, Aria
• Format: Conference Proceeding Journal Article
• Language: English
• Published: IEEE 01.07.2016
• Subjects: Allocations; Broadcasting; Channels; Coding; Constellations; Constraints; Encoding; Modulation; Multilevel; Optimization; Pragmatics; Receivers; Resource management
• ISSN: 2157-8117
• DOI: 10.1109/ISIT.2016.7541282

For the Gaussian broadcast channel, transmission at or near the capacity subject to a specific modulation constraint, has been an essentially open problem. The capacity of the AWGN broadcast is achieved by superposition coding, but superposition of individual coded modulations does not in general obey a predefined constellation. We approach this coded modulation problem with multilevel coding (MLC) which is known to achieve the constellation constrained capacity in the point-to-point channel. In channels involving multiple transmitters or receivers, the application of multilevel coding has received little attention. In this paper, a method is proposed that decomposes superposition coding into binary multilevel superposition coding. The problem of rate allocation through every level for each user is studied and a pragmatic rate allocation procedure is presented. The problem of rate allocation to levels is studied and a pragmatic method for its solution is proposed. The coded modulation with proposed rate allocation achieves rates that are very close to the constellation constrained capacity.