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Please use this identifier to cite or link to this item: http://hdl.handle.net/2005/828

Title: Diversity-Mutiplexing Tradeoff Of Asynchronous Cooperative Relay Networks And Diversity Embedded Coding Schemes
Authors: Naveen, N
Advisors: Vijay Kumar, P
Keywords: Multiplexing
Coding Theory
Information Theory
Fading Wireless Channels
Space-time Codes
MIMO Broadcast Channels
Asynchronous Cooperative Relay Networks
Diversity Embedded Coding
Diversity-Multiplexing Tradeoff (DMT)
Slot-offset Model
Diversity Embedding
Diversity Gain Region (DGR)
Submitted Date: Jul-2008
Series/Report no.: G22603
Abstract: This thesis consists of two parts addressing two different problems in fading channels. The first part deals with asynchronous cooperative relay communication. The assumption of nodes in a cooperative communication relay network operating in synchronous fashion is often unrealistic. In this work we consider two different models of asynchronous operation in cooperative-diversity networks experiencing slow fading and examine the corresponding Diversity-Multiplexing Tradeoffs (DMT). For both models, we propose protocols and distributed space-time codes that asymptotically achieve the transmit diversity bound on DMT for all multiplexing gains and for number of relays N ≥ 2. The distributed space-time codes for all the protocols considered are based on Cyclic Division Algebras (CDA). The second part of the work addresses the DMT analysis of diversity embedded codes for MIMO channels. Diversity embedded codes are high rate codes that are designed so that they have a high diversity code embedded within them. This allows a form of opportunistic communication depending on the channel conditions. The high diversity code ensures that at least a part of the information is received reliably, whereas the embedded high rate code allows additional information to be transferred if the channel is good. This can be thought of coding the data into two streams: high priority and low priority streams so that the high priority stream gets a better reliability than the lower priority stream. We show that superposition based diversity embedded codes in conjunction with naive single stream decoding is sub-optimal in terms of the DM tradeoff. We then construct explicit diversity embedded codes by the superposition of approximately universal space-time codes from CDAs. The relationship between broadcast channels and the diversity embedded setting is then utilized to provide some achievable Diversity Gain Region (DGR) for MIMO broadcast Channels.
URI: http://etd.iisc.ernet.in/handle/2005/828
Appears in Collections:Electrical Communication Engineering (ece)

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