Abstract

We consider a secondary user with energy harvesting capability. We design access schemes for the secondary user which incorporate random spectrum sensing and random access, and which make use of the primary automatic repeat request (ARQ) feedback. The sensing and access probabilities are obtained such that the secondary throughput is maximized under the constraints that both the primary and secondary queues are stable and that the primary queueing delay is kept lower than a specified value needed to guarantee a certain quality of service (QoS) for the primary user. We consider spectrum sensing errors and assume multipacket reception (MPR) capabilities. Numerical results are presented to show the enhanced performance of our proposed system over a random access system, and to demonstrate the benefit of leveraging the primary feedback.

Highlights

  • Cognitive radio technology provides an efficient means of utilizing the radio spectrum [2]

  • We propose a novel access and sensing schemes where the secondary user (SU) possibly senses the channel for a certain fraction of the time slot duration and accesses the channel with some access probability that depends on the sensing outcome

  • The sensing and access probabilities are obtained such that the secondary throughput is maximized under the stability of the primary queue and that the primary queueing delay is kept lower than a specified value needed to guarantee a certain quality of service (QoS) for the primary user (PU)

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Summary

Introduction

Cognitive radio technology provides an efficient means of utilizing the radio spectrum [2]. In [15], the authors use a partially observable Markov decision process (POMDP) to optimize the secondary action on the basis of the spectrum sensing outcome and primary ARQ feedback. The SU may access the channel probabilistically without sensing in order to utilize the whole slot duration for transmission Whereas in the second problem-formulation, we include a constraint on the primary queueing delay to the optimization problem for delay-aware PUs. The sensing and access probabilities are obtained such that the secondary throughput is maximized under the stability of the primary queue and that the primary queueing delay is kept lower than a specified value needed to guarantee a certain QoS for the PU.

System Model
Secondary Access Without Employing Primary Feedback
First Dominant System
Second Dominant System
Feedback-based Access
First dominant system
Second dominant system
Delay-Aware Primary Users
Primary Queueing Delay for System S with Saturated SU
Primary Queueing Delay for System S f with Saturated SU
Numerical Results and Conclusions
Full Text
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