Handoff Delay-Based Call Admission Control in Cognitive Radio Networks

Ling WANG  Qicong PENG  Qihang PENG  

IEICE TRANSACTIONS on Communications   Vol.E97-B   No.1   pp.49-55
Publication Date: 2014/01/01
Online ISSN: 1745-1345
DOI: 10.1587/transcom.E97.B.49
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Network
cognitive radio,  spectrum handoff,  call admission control,  preemptive,  queuing theory,  

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In this paper, we investigate how to achieve call admission control (CAC) for guaranteeing call dropping probability QoS which is caused by handoff timeout in cognitive radio (CR) networks. When primary user (PU) appears, spectrum handoff should be initiated to maintain secondary user (SU)'s link. We propose a novel virtual queuing (VQ) scheme to schedule spectrum handoff requests sent by multiple SUs. Unlike the conventional first-come-first-served (FCFS) scheduling, resuming transmission in the original channel has higher priority than switching to another channel. It costs less because it avoids the cost of signaling frequent spectrum switches. We characterize the handoff delay on the effect of PU's behavior and the number of SUs in CR networks. And user capacity under certain QoS requirement is derived as a guideline for CAC. The analytical results show that call dropping performance can be greatly improved by CAC when a large amount of SUs arrives fast as well as the VQ scheme is verified to reduce handoff cost compared to existing methods.