QoS Protection in Cognitive Wireless Mesh Networks: Issues and Solutions

Abstract

Radio links in cognitive wireless mesh networks (CWMN) exhibit fluctuations in link capacity due to the unpredictable nature of the occupancy of frequency holes by primary users in addition to variability in the quality of wireless channels. These variations prevent quality of service (QoS) from being delivered on CWMNs solely by using traditional mechanisms, i.e. call admission control, bandwidth reservation, queue management and packet scheduling. In [1] a quality of service protection (QoSP) architecture has been proposed which extends the failure protection mechanisms used in MPLS networks to protect QoS for CWMNs. This paper aims to provide solutions for the open QoSP-related issues: (1) a measure called effective capacity is defined and estimated to characterize the fluctuation in link capacity, (2) a policy is provided to reach decisions about path switching when QoS degradation happens and (3) a margin guard call admission control and an adaptive method to find suitable margin guards is proposed to keep the probability of successful path restoration above a predefined threshold.