Spectral efficiency enhancement in multi-channel systems using redundant transmission and diversity reception

Haewoon Nam, Young Chai Ko, Mohamed Slim Alouini

Research output: Contribution to journalArticlepeer-review

13 Citations (Scopus)


We first consider conventional multi-channel systems with fixed-power variable-rate transmission of independent data streams as a function of channel variations. In these conventional systems, no data is transmitted through the sub-channels whose received signal strength is below a certain cutoff threshold. We then propose new hybrid adaptive modulation and diversity schemes for multi-channel transmission systems. The proposed hybrid schemes attempt to increase the overall spectral efficiency by (i) transmitting redundant information symbols through the deeply faded sub-channels that are not to be used in conventional multi-channel systems and then (ii) diversity combining these replicas at the receiver end. We evaluate the performance of the newly proposed hybrid schemes and compare their spectral efficiency with that of (i) the conventional scheme and (ii) a benchmark scheme which maximizes the overall spectral efficiency but is too complex for practical implementation. We show using some selected numerical examples that the proposed hybrid schemes offer spectral efficiency very close to that of the optimal scheme with much reduced complexity.

Original languageEnglish
Article number4543066
Pages (from-to)2143-2153
Number of pages11
JournalIEEE Transactions on Wireless Communications
Issue number6
Publication statusPublished - 2008 Jun

Bibliographical note

Funding Information:
Manuscript received June 22, 2006; revised April 22, 2007 and December 23, 2007; accepted April 4, 2008. The associate editor coordinating the review of this paper and approving it for publication was S. Kishore. This is an extended version of work which was presented in the IEEE Wireless Communications and Networking Conference (WCNC 2007), Hong Kong, China, March 2007. This research was supported by the MKE(Ministry of Knowledge Economy), Korea, under the ITRC(Information Technology Research Center) support program supervised by the IITA(Institute of Information Technology Assessment)(IITA-2008-C1090-0801-0019).


  • Adaptive modulation
  • Diversity combining
  • Multi-channel wireless systems

ASJC Scopus subject areas

  • Computer Science Applications
  • Electrical and Electronic Engineering
  • Applied Mathematics


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