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A spectrally efficient transmission scheme for half-duplex decode-and-forward relaying
KTH, School of Electrical Engineering (EES), Communication Theory.
KTH, School of Electrical Engineering (EES), Communication Theory.
2007 (English)In: GLOBECOM 2007: 2007 IEEE GLOBAL TELECOMMUNICATIONS CONFERENCE, 2007, 1663-1667 p.Conference paper, Published paper (Refereed)
Abstract [en]

We propose a spectrally efficient transmission scheme for the half-duplex relay channel. In the proposed scheme, the relay combines N detected r-dimensional symbols and generates M new r-dimensional symbols, where M < N, using a linear transformation. The proposed linear transformation preserves the signal energy, and it facilitates decoupled symbol detection at the receiver.

We also present an optimized design for the case of complex scalar modulation (r = 2) with N = 2 and M = 1. This design increases the spectral efficiency by 33% compared to conventional decode- or amplify-and-forward relaying.

Place, publisher, year, edition, pages
2007. 1663-1667 p.
Series
IEEE Global Telecommunications Conference (Globecom), ISSN 1930-529X
Keyword [en]
Communication channels (information theory), Optimization, Signal analysis, Signal receivers, Complex scalar modulation, Linear transformation, Signal energy
National Category
Telecommunications
Identifiers
URN: urn:nbn:se:kth:diva-8306DOI: 10.1109/GLOCOM.2007.320ISI: 000257505701124Scopus ID: 2-s2.0-39349083565ISBN: 978-1-4244-1042-2 (print)OAI: oai:DiVA.org:kth-8306DiVA: diva2:13591
Conference
IEEE Global Telecommunications Conference (GLOBECOM 07), Washington, DC, NOV 26-30, 2007
Note
QC 20101118 Tidigare titel: A Spectrally Efficient Transmission Scheme for Half-Duplex DF RelayingAvailable from: 2008-04-30 Created: 2008-04-30 Last updated: 2010-11-18Bibliographically approved
In thesis
1. Relaying Protocols for Wireless Networks
Open this publication in new window or tab >>Relaying Protocols for Wireless Networks
2008 (English)Licentiate thesis, comprehensive summary (Other scientific)
Abstract [en]

Motivated by current applications in multihop transmission and ad hoc networks, the classical three-node relay channel consisting of a source-destination pair and a relay has received significant attention. One of the crucial aspects of the relay channel is the design of proper relaying protocols, i.e., how the relay should take part into transmission. The thesis addresses this problem and provides a partial answer to that.

In this thesis, we propose and study two novel relaying protocols. The first one is based on constellation rearrangement (CR) and is suitable for higher-order modulation schemes. With CR, the relay uses a bit-symbol mapping that is different from the one used by the source. We find the optimal bit-symbol mappings for both the source and the relay and the associated optimal detectors, and show that the improvement over conventional relaying with Gray mapping at the source and the relay can amount to a power gain of several dB. This performance improvement comes at no additional power or bandwidth expense, and at virtually no increase in complexity. The second one is a half-duplex decode-and-forward (DF) relaying scheme based on partial repetition (PR) coding at the relay. With PR, if the relay decodes the received message successfully, it re-encodes the message using the same channel code as the one used at the source, but retransmits only a fraction of the codeword. We analyze the proposed scheme and optimize the cooperation level (i.e., the fraction of the message that the relay should transmit). We compare our scheme with conventional repetition in which the relay retransmits the entire decoded message, and with parallel coding, and additionally with dynamic DF. The finite SNR analysis reveals that the proposed partial repetition can provide a gain of several dB over conventional repetition. Surprisingly, the proposed scheme is able to achieve the same performance as that of parallel coding for some relay network configurations, but at a much lower complexity.

Additionally, the thesis treats the problem of resource allocation for collaborative transmit diversity using DF protocols with different type of CSI feedback at the source. One interesting observation that emerges is that the joint powerbandwidth allocation only provides marginal gain over the relaying protocols with optimal bandwidth allocation.

Place, publisher, year, edition, pages
Stockholm: KTH, 2008. vii, 13 p.
Series
Trita-EE, ISSN 1653-5146 ; 2008:019
Keyword
The relay channel, constellation rearrangement, decode-and-forward, resource allocation
National Category
Telecommunications
Identifiers
urn:nbn:se:kth:diva-4716 (URN)
Presentation
2008-05-16, Q21, Q, Osquldas väg 6, KTH, Stockholm, Sweden, 13:15
Opponent
Supervisors
Note
QC 20101119Available from: 2008-04-30 Created: 2008-04-30 Last updated: 2010-11-19Bibliographically approved

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  • Other locale
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Output format
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  • asciidoc
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