This paper considers the problem of efficient usage of subcarriers in downlink Orthogonal Frequency-Division Multiple Access (OFDMA) multi-hop cellular networks. Multi-hop transmission can either save or waste subcarriers depending on quality of service (QoS) requirements, interference from other cells, and the location of a given mobile station (MS). Preventing unnecessary usage of multi-hop transmission requires the use of a transmission mode selection (TMS) scheme, and we propose two types of TMS in this paper. The first of these is distance-based TMS (TMS-D), which determines the transmission mode based on the MS's location, and the second is subcarrier-based TMS (TMS-S), which selects whichever transmission mode uses fewer subcarriers. Numerical results on blocking probability demonstrate that TMS improves overall subcarrier usage efficiency, meaning that more MSs can be supported with low blocking probability within a cell. Furthermore, the performance of TMSS, even given its higher complexity, is shown to be superior to that of TMS-D.
Bibliographical noteFunding Information:
Manuscript received April 21, 2007; revised August 14, 2007 and January 22, 2008; accepted June 9, 2008. The associate editor coordinating the review of this paper and approving it for publication was A. Hjorungnes. This work was supported in part by Korea Science & Engineering Foundation through the NRL Program (Grant R0A-2007-000-20043-0), and in part by the 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-C1090-0803-0002).
All Science Journal Classification (ASJC) codes
- Computer Science Applications
- Electrical and Electronic Engineering
- Applied Mathematics