On broadcast approach for multiple access channel

Kazemi, Samia Binte
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Other Contributors
Tajer, Ali
Vastola, Kenneth S.
Saulnier, Gary J.
Issue Date
Electrical engineering
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This electronic version is a licensed copy owned by Rensselaer Polytechnic Institute, Troy, NY. Copyright of original work retained by author.
Full Citation
A broadcast strategy for multiple access communication over slowly fading channels is introduced. It is an extension of the existing broadcast approaches to multiple access communication, in which the channel state information is known to the receiver only. In this strategy, the transmitters split their information streams into multiple independent coded information layers, each adapted to a specific actual channel realization. The major distinction between the proposed strategy and the existing one is that in the existing approach, each transmitter adapts its transmission strategy only to the fading process of its direct channel to the receiver, hence directly adopting a single-user strategy previously designed for the single-user channels. However, the contribution of each user to a network-wide measure (e.g., sum-rate capacity) depends not only on the users' direct channel to the receiver, but also on the qualities of other channels. Driven by this premise, an alternative broadcast strategy is proposed here in which the transmitters adapt their transmissions to the combined state resulting from both users' channels. This leads to generating a larger number of information layers by each transmitter and a different decoding strategy by the receiver. The fundamental trade-off among the rates of different information layers is established. Capacity region characterized by sum rates of two users' equivalent layers is derived for independent and finite state channel realization. This region turns out to be larger than the equivalent capacity region for existing broadcast strategy which in turn provides a larger average rate. This approach is extended to continuous channels with infinite states and corresponding average rate is expressed as a function of joint distribution function of channel states and power density function among the transmission layers.
August 2016
School of Engineering
Dept. of Electrical, Computer, and Systems Engineering
Rensselaer Polytechnic Institute, Troy, NY
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