An efficient random access scheme for OFDMA systems with implicit message transmission

Ping Zhou, Honglin Hu, Haifeng Wang, Hsiao Hwa Chen

Research output: Contribution to journalArticlepeer-review

42 Citations (Scopus)


Random access channel (RACH) is usually used for initial channel access, bandwidth request, etc. In this paper, we analyze the throughput and access delay performance of the RACH in an orthogonal frequency division multiple access (OFDMA) system. A closed-form expression of the RACH throughput is presented and its mean access delays under both binary exponential and uniform backoff policies have also been derived. Moreover, to further improve the utilization of RACH in an OFDMA system, we propose a novel message transmission scheme in a shared RACH. The message in the proposed scheme can be sent implicitly in the cyclic-shifted preambles which make the transmission much more reliable in a contention based RACH. Meanwhile, performance of the preamble detection has also been improved by the redundant information conveyed in messages. Finally, simulation results will demonstrate performance gains of the proposed scheme.

Original languageEnglish
Article number4570245
Pages (from-to)2790-2797
Number of pages8
JournalIEEE Transactions on Wireless Communications
Issue number7
Publication statusPublished - 2008 Jul

All Science Journal Classification (ASJC) codes

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


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