liu.seSearch for publications in DiVA
Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Bits-to-Symbol Mappings for Superposition Coding Based HARQ Systems
Linköping University, Department of Electrical Engineering, Communication Systems. Linköping University, The Institute of Technology.
Linköping University, Department of Electrical Engineering, Communication Systems. Linköping University, The Institute of Technology.ORCID iD: 0000-0002-7599-4367
2013 (English)In: Proceedings of the IEEE Wireless Communications and Networking Conference (WCNC), Institute of Electrical and Electronics Engineers (IEEE), 2013, 2468-2472 p.Conference paper, Published paper (Refereed)
Abstract [en]

We consider the mapping of bits-to-superimposed constellation symbols in terms of the achievable rate on the channel for the HARQ system using superposition coding as proposed in [2]. We show that using a Gray mapping of bits-to-superimposed constellation symbols has better performance thanthe conventional natural mapping that results from superposition in signal space, for all the values of the superposition ratio. We also show through link-level simulations that the predicted gains in terms of achievable rate can be realized in practice using LDPC codes. Furthermore, we show that the optimal superposition ratio for the Gray mapping case results in conventional higher order constellation symbols after the superposition operation.

Place, publisher, year, edition, pages
Institute of Electrical and Electronics Engineers (IEEE), 2013. 2468-2472 p.
Series
IEEE Wireless Communications and Networking Conference. Proceedings, ISSN 1525-3511
Keyword [en]
Superposition coding, bits-to-symbol mapping, hybrid ARQ
National Category
Communication Systems
Identifiers
URN: urn:nbn:se:liu:diva-87279DOI: 10.1109/WCNC.2013.6554948ISBN: 978-1-4673-5938-2 (print)ISBN: 978-1-4673-5937-5 (print)OAI: oai:DiVA.org:liu-87279DiVA: diva2:588320
Conference
IEEE Wireless Communications and Networking Conference, WCNC 2013, 7-10 April, Shanghai; China
Note

The previous status of this article was Manuscript and the working title was Bits-to-Symbol Mappings for Superposition Coding.

Available from: 2013-04-03 Created: 2013-01-15 Last updated: 2017-01-13Bibliographically approved
In thesis
1. HARQ Systems: Resource Allocation, Feedback Error Protection, and Bits-to-Symbol Mappings
Open this publication in new window or tab >>HARQ Systems: Resource Allocation, Feedback Error Protection, and Bits-to-Symbol Mappings
2013 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Reliability of data transmission is a fundamental problem in wireless communications. Fading in wireless channels causes the signal strength to vary at the receiver and this results in loss of data packets. To improve the reliability, automatic repeat request (ARQ) schemes were introduced. However these ARQ schemes suffer from a reduction in the throughput. To address the throughput reduction, conventional ARQ schemes were combined with forward error correction (FEC) schemes to develop hybrid-ARQ (HARQ) schemes. For improving the reliability of data transmission, HARQ schemes are included in the present wireless standards like LTE, LTE-Advanced and WiMAX.

Conventional HARQ systems use the same transmission power and the same number of channel uses in different ARQ rounds. However this is not optimal in terms of minimizing the average transmit power or the average energy spent for successful transmission of a data packet. We address this issue in the first part of the dissertation, where we consider optimal resource allocation in HARQ systems with a limit on the maximum number of allowed transmissions for a data packet. Specifically, we consider the problem of minimizing the packet drop probability (PDP) under an average transmit power constraint or equivalently minimizing the average transmit power under a fixed PDP constraint. We consider both incremental redundancy (IR)-based and Chase combining (CC)-based HARQ systems in our work. For an IR-HARQ system, for the special case of two allowed transmissions for each packet, we provide a solution for the optimal number of channel uses and the optimal power to be used in each ARQ round. For a CC-HARQ system, we solve the problem of optimal power allocation in i.i.d. Rayleigh fading channels as well as correlated Rayleigh fading channels. For the CC-HARQ case, we also provide a low complexity geometric programming (GP) solution using an approximation of the outage probability expression.

HARQ systems conventionally use one bit acknowledgement (ACK)/negative ACK (NACK) feedback from the receiver to the transmitter. In the 3GPP-LTE systems, one method for sending these HARQ acknowledgement bits is to jointly code them with the other control signaling information using a specified Reed-Muller code consisting of 20 coded bits. Even though the resources used for sending this control signaling information can inherently provide a diversity gain, the Reed-Muller code with such a short block size is not good at extracting all of the available diversity. To address this issue, in the second part of this dissertation, we propose two new methods: i) based on complex-field coding (CFC), and ii) using repetition across frequency bands, to extract the inherent diversity available in the channel resources and improve the error protection for the HARQ acknowledgement bits along with the other control signaling information. In the second part of the dissertation, we also propose a new signal space diversity (SSD) scheme, which results in transmit signals having constant envelope (CE). The proposed CE-SSD scheme results in a better overall power efficiency due to the reduced back-off requirements on the radio frequency power amplifier. Moreover, the proposed CE-SSD technique can be useful for application scenarios involving transmission of small number of information bits, such as in the case of control signaling information transmission.

In conventional HARQ systems, during the retransmission phase, the channel resources are exclusively used for the retransmitted data packet. This is not optimal in terms of efficient resource utilization. For efficient utilization of channel resources during the retransmissions, a superposition coding (SPC) based HARQ scheme was proposed in the literature. In an SPC based HARQ system, an erroneous packet is transmitted together with a new data packet by superposition in the Euclidean space. In the final part of this dissertation, we study performance of different bits-to-symbol mappings for such an SPC based HARQ system.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2013. 43 p.
Series
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 1526
Keyword
HARQ Systems, Resource Allocation, Geometric Programming, 3GPP-LTE, PUCCH Format 2, Complex-field coding, Signal Space Diversity, Optimization, Superposition Coding
National Category
Communication Systems Telecommunications
Identifiers
urn:nbn:se:liu:diva-96021 (URN)978-91-7519-574-2 (ISBN)
Public defence
2013-09-27, Visionen, Hus B, Campus Valla, Linköpings universitet, Linköping, 10:56 (English)
Opponent
Supervisors
Available from: 2013-09-11 Created: 2013-08-13 Last updated: 2017-01-13Bibliographically approved
2. Improved Techniques for Retransmission and Relaying in Wireless Systems
Open this publication in new window or tab >>Improved Techniques for Retransmission and Relaying in Wireless Systems
2011 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

The last three decades have seen significant advances in the wireless communication field. As the data rates of wireless systems are increasing, the demand for mobile services also is increasing rapidly. Like other natural resources, radio spectrum suitable for mobile wireless communications is also limited. In order to keep up with this ever increasing demand, there is a requirement of new signal processing algorithms.

Diversity is a technique used in wireless systems to combat the effects of fading and thereby improve reliability of data transfer. There are many ways in which algorithms can exploit diversity in wireless channels. Hybrid-automatic repeat request (H-ARQ) schemes and relaying mechanisms are two such diversity extracting techniques. Even though these diversity achieving techniques have been well understood in theory, there are many ways in which one can optimize these techniques for specific application scenarios.In this thesis, we focus on improving the performance of retransmission schemes and relaying systems.

In the first part of the thesis, we improve the performance of H-ARQ schemes in the 3GPP- long term evolution (LTE) system by improving the performance of feedback signaling. We employ complex-field coding to extract the inherent frequency diversity available in the resources. Next, we provide a sub-optimal solution to the outage-optimal power allocation problem in incremental redundancy based H-ARQ system, whose performance is practically the same as that of the optimal solution.

In the later part of the thesis, we propose a retransmission scheme based on superposition coding (SPC) for the symmetric relaying scenario. We provide packet error probability (PEP) expressions and solutions for the optimal fraction of power allocated for the partners' data. Finally, we study the optimal bits-to-symbol mappings for SPC and its effect on an H-ARQ scheme and the symmetric relaying scenario using SPC.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2011. 19 p.
Series
Linköping Studies in Science and Technology. Thesis, ISSN 0280-7971 ; 1494
Keyword
Hybrid-ARQ, relaying schemes, superposition coding, 3GPP- LTE
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-68289 (URN)978-91-7393-144-1 (ISBN)
Presentation
2011-06-17, Visionen, Hus B, Campus Valla, Linköpings universitet, Linköping, 13:15 (English)
Opponent
Supervisors
Available from: 2011-05-27 Created: 2011-05-17 Last updated: 2017-01-13Bibliographically approved

Open Access in DiVA

fulltext(219 kB)988 downloads
File information
File name FULLTEXT01.pdfFile size 219 kBChecksum SHA-512
4fa0875c94c995a456543ee2393406a1607e108ee87c5af736b0c275954de9f2c4ca15acb7b0142c51271cf2739669115b417b3d6aac2445679bbb68dca8812e
Type fulltextMimetype application/pdf

Other links

Publisher's full text

Authority records BETA

Tumula V. K., ChaitanyaLarsson, Erik G

Search in DiVA

By author/editor
Tumula V. K., ChaitanyaLarsson, Erik G
By organisation
Communication SystemsThe Institute of Technology
Communication Systems

Search outside of DiVA

GoogleGoogle Scholar
Total: 988 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

doi
isbn
urn-nbn

Altmetric score

doi
isbn
urn-nbn
Total: 599 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf