Enhanced Primary and Secondary Performance Through Cognitive Relaying and Leveraging Primary Feedback

• Published in: IEEE transactions on vehicular technology Vol. 63; no. 5; pp. 2236 - 2247
• Main Authors: Hamza, Doha, Aissa, Sonia
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.06.2014; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Applied sciences; ARQ feedback; Automatic repeat request; Channels; Cognitive radio; cognitive relaying; Connection and protection apparatus; Delay; delay analysis; Delays; Electrical engineering. Electrical power engineering; Exact sciences and technology; Feedback; Information, signal and communications theory; Markov chains; Markov processes; Mathematical analysis; Queues; Radiocommunication specific techniques; Radiocommunications; Receivers; Relaying; Relays; Sensors; Signal and communications theory; Signal representation. Spectral analysis; Signal, noise; spectrum sensing; Systems, networks and services of telecommunications; Telecommunications; Telecommunications and information theory; Terminals; Throughput; Transmission and modulation (techniques and equipments); cognitive radio (CR); Markov chains; cognitive relaying; delay analysis; Automatic repeat request (ARQ) feedback; spectrum sensing; Performance evaluation; Relaying; Relay; Information rate; Feedback regulation; Markov chain; Feedback; Spectrum analysis; Traffic control; Delay time; Queue; Teletraffic; Resource sharing; Failures; Information transmission; Queueing system; Traffic management; Signal analysis; Automatic repeat request; Software radio
• ISSN: 0018-9545; 1939-9359
• DOI: 10.1109/TVT.2013.2292532

We consider a spectrum-sharing system, where the primary terminal operates in a time-slotted fashion and is active only when it has a packet to send. The secondary terminal uses spectrum sensing results and the primary automatic repeat request (ARQ) feedback to access the channel probabilistically. To enhance the primary's system performance, the secondary user (SU) acts as a relay for the primary user (PU) in the event of transmission failure on the direct link of the latter. Closed-form expressions for the primary and secondary throughputs are obtained for the described scheme. The optimal medium access probabilities are then obtained by maximizing the secondary throughput subject to constraints that guarantee the stability of the considered queues, a minimum primary throughput, and a maximum primary queueing delay. The results clearly indicate the benefits of cognitive relaying in enhancing the throughput performance for both the PU and SU. Furthermore, by guaranteeing minimum rate and maximum delay requirements, our scheme is shown to provide a definitive notion of protection for the licensed users of the network.