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Relaying Protocols for Wireless Networks
KTH, School of Electrical Engineering (EES), Communication Theory.
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 [en]
The relay channel, constellation rearrangement, decode-and-forward, resource allocation
National Category
Telecommunications
Identifiers
URN: urn:nbn:se:kth:diva-4716OAI: oai:DiVA.org:kth-4716DiVA: diva2:13592
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
List of papers
1. Improving Collaborative Transmit Diversity by Using Constellation Rearrangement
Open this publication in new window or tab >>Improving Collaborative Transmit Diversity by Using Constellation Rearrangement
2007 (English)In: IEEE Wireless Communications and Networking Conference, WCNC, 2007, 804-808 p.Conference paper, Published paper (Refereed)
Abstract [en]

We propose an enhancement to cooperative transmit diversity based on uncoded detect-and-forward, by using so-called constellation rearrangement (CR) at the relay. 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.

Series
IEEE Wireless Communications and Networking Conference, ISSN 1525-3511
Keyword
Bandwidth, Diversity reception, Signal detection, Telecommunication systems, Collaborative transmit diversity, Constellation rearrangement, Optimal bit-symbol mappings, Optimal detectors
National Category
Telecommunications
Identifiers
urn:nbn:se:kth:diva-8302 (URN)10.1109/WCNC.2007.153 (DOI)000252337101059 ()2-s2.0-36349018202 (Scopus ID)1424406595 (ISBN)978-142440659-3 (ISBN)
Conference
2007 IEEE Wireless Communications and Networking Conference, WCNC 2007; Kowloon; China; 11 March 2007 through 15 March 2007
Note

Conference: IEEE Wireless Communications and Networking Conference. Hong Kong, PEOPLES R CHINA. MAR 11-15, 2007

Available from: 2008-04-30 Created: 2008-04-30 Last updated: 2015-07-15Bibliographically approved
2. Receiver Design for Wireless Relay Channels with Regenerative Relays
Open this publication in new window or tab >>Receiver Design for Wireless Relay Channels with Regenerative Relays
2007 (English)In: IEEE International Conference on Communications, 2007, 4034-4039 p.Conference paper, Published paper (Refereed)
Abstract [en]

We develop a general framework for design of receivers for the wireless relay channel. We derive the optimum detectors for various degrees of channel state information (CSI) at the destination. We consider both the case when the destination has access to full knowledge of the CSI and the case when it only knows the statistics of the channel. High-SNR and low-SNR approximations of the detectors are presented as well.

Series
IEEE International Conference on Communications, ISSN 1550-3607
Keyword
Channel state information, Signal detection, Signal to noise ratio, Telecommunication repeaters, Wireless networks, Receiver design, Regenerative relays, Wireless relay channels
National Category
Telecommunications
Identifiers
urn:nbn:se:kth:diva-8303 (URN)10.1109/ICC.2007.664 (DOI)000257882502187 ()2-s2.0-38549132527 (Scopus ID)1424403537 (ISBN)978-142440353-0 (ISBN)
Conference
2007 IEEE International Conference on Communications, ICC'07; Glasgow, Scotland; United Kingdom; 24 June 2007 through 28 June 2007
Note

QC 20150713

Available from: 2008-04-30 Created: 2008-04-30 Last updated: 2015-07-13Bibliographically approved
3. Cooperative Transmission Based on Decode-and-Forward Relaying with Partial Repetition Coding
Open this publication in new window or tab >>Cooperative Transmission Based on Decode-and-Forward Relaying with Partial Repetition Coding
2009 (English)In: IEEE Transactions on Wireless Communications, ISSN 1536-1276, E-ISSN 1558-2248, Vol. 8, no 4, 1716-1725 p.Article in journal (Refereed) Published
Abstract [en]

We propose a novel half-duplex decode-and-forward relaying scheme based on partial repetition coding at the relay. In the proposed scheme, 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, with parallel coding, and additionally with dynamic decode-and-forward (DDF). We provide a finite-SNR analysis for all the collaborative schemes. The analysis reveals that the proposed partial repetition method can provide a gain of several dB over conventional repetition. It also shows that in general, power allocation is less important provided that one optimally allocates bandwidth. 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.

Keyword
Relay channel, cooperative diversity, parallel coding, repetition coding, resource allocation, power allocation, bandwidth allocation
National Category
Telecommunications
Identifiers
urn:nbn:se:kth:diva-8304 (URN)10.1109/TWC.2009.070674 (DOI)000265373100022 ()2-s2.0-65949118492 (Scopus ID)
Note
QC 20101118 Uppdaterad från in press till published (20101118). Tidigare titel: Cooperative Transmission Based on DF Relaying with Partial Repetition CodingAvailable from: 2008-04-30 Created: 2008-04-30 Last updated: 2017-12-14Bibliographically approved
4. Analytical results on block length optimization for decode-and-forward relaying with CSI feedback
Open this publication in new window or tab >>Analytical results on block length optimization for decode-and-forward relaying with CSI feedback
2007 (English)In: 2007 IEEE 8th Workshop on Signal Processing Advances in Wireless Communications, IEEE , 2007, 96-100 p.Conference paper, Published paper (Refereed)
Abstract [en]

We consider block length optimization for collaborative transmit diversity using a decode-and-forward protocol assuming that the source and the relay have access to the magnitudes of all path gains. Moreover, we propose a simple scheme which requires only one bit of channel state information (CSI) feedback. We analyze the outage probabilities of all schemes for both selection combining and maximum ratio combining (MRC) at the destination. Analytical results show that even one bit of CSI feedback can provide a significant gain over conventional (non-adaptive) collaborative schemes.

Place, publisher, year, edition, pages
IEEE, 2007
Keyword
Channel state information, Communication channels (information theory), Feedback, Information retrieval, Optimization, Signal processing, State feedback, Telecommunication, Analytical results, Block lengths, Channel state information feedback, CSI feedback, Decode-and-forward protocol, Decode-and-forward relaying, Maximum Ratio Combining, Selection combining, Transmit diversity, Wireless communications
National Category
Telecommunications
Identifiers
urn:nbn:se:kth:diva-8305 (URN)10.1109/SPAWC.2007.4401292 (DOI)000255431000020 ()2-s2.0-48049091377 (Scopus ID)978-1-4244-0954-9 (ISBN)
Conference
8th IEEE Workshop on Signal Processing Advances in Wireless Communications, Helsinki, Finland, June 17-20, 2007
Note

QC 20101118

Available from: 2008-04-30 Created: 2008-04-30 Last updated: 2014-11-04Bibliographically approved
5. A spectrally efficient transmission scheme for half-duplex decode-and-forward relaying
Open this publication in new window or tab >>A spectrally efficient transmission scheme for half-duplex decode-and-forward relaying
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.

Series
IEEE Global Telecommunications Conference (Globecom), ISSN 1930-529X
Keyword
Communication channels (information theory), Optimization, Signal analysis, Signal receivers, Complex scalar modulation, Linear transformation, Signal energy
National Category
Telecommunications
Identifiers
urn:nbn:se:kth:diva-8306 (URN)10.1109/GLOCOM.2007.320 (DOI)000257505701124 ()2-s2.0-39349083565 (Scopus ID)978-1-4244-1042-2 (ISBN)
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

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