Unified Packet Scheduling Method Considering Delay Requirement in OFCDM Forward Link Broadband Wireless Access

Yoshiaki OFUJI  Sadayuki ABETA  Mamoru SAWAHASHI  

Publication
IEICE TRANSACTIONS on Communications   Vol.E88-B   No.1   pp.170-182
Publication Date: 2005/01/01
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Section on Multi-carrier Signal Processing Techniques for Next Generation Mobile Communications--Part 1)
Category: Scheduling
Keyword: 
fast packet scheduling,  OFCDM,  QoS,  delay,  

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Summary: 
This paper proposes a unified packet scheduling method that considers the delay requirement of each traffic data packet whether real time (RT) or non-real time (NRT), the channel conditions of each accessing user, and the packet type in hybrid automatic repeat request (ARQ), i.e., either initially transmitted packet or retransmitted packet, in the forward link for Orthogonal Frequency and Code Division Multiplexing (OFCDM) wireless access. In the proposed packet scheduling method, the overall priority function is decided based on PTotal = αDelayPDelay + αTypePType + αSINRPSINR (PDelay, PType, and PSINR are the priority functions derived from the delay requirement, type of packet, and the received signal-to-interference plus noise power ratio (SINR), respectively, and αDelay, αType, and αSINR are the corresponding weighting factors). The computer simulation results show that the weighting factor of each priority function as αTypeDelay = 0.6, αSINRDelay = 0.4 assuming the linear-type function in PDelay and a constant-type function in PType is optimized. Furthermore, we show that the outage probability for achieving the packet loss rate (PLR) of less than 10-3 for non-real time (NRT) traffic users employing the proposed packet scheduling method is reduced by approximately two orders of magnitude compared to that using the Priority Queuing (PQ) method while maintaining the PLR of real-time (RT) traffic users at the same level as that using the PQ method.