Service response time of elastic data traffic in cognitive radio networks with SPT service discipline

Cognitive radio networks (CRNs) have emerged as a promising solution to spectrum under-utilization and congestion. Supporting quality of service (QoS)-aware services over CRNs is always challenging due to the random spectrum availability. In this work, we consider a single channel CRN with centralized control, operating over a time-slotted primary network, accessing the channel at the spectrum holes without interfering with primary users. The central controller transmits elastic data traffic to the secondary users (SUs). The service response time is an important QoS parameter for elastic data traffic, defined as the duration from the instant that an SU requests a data file from the central controller until it completes the reception. We analyze the response time under the shortest processing time (SPT) first service discipline, and compare it with the processor sharing (PS) service discipline. We show that the SPT service discipline outperforms the PS service discipline in medium and heavy traffic load conditions. The response time analysis can be used for call admission control to ensure service satisfaction.