Cognitive Proactive and Reactive DF Relaying Schemes under Joint Outage and Peak Transmit Power Constraints

Abstract

Abstract-Cognitive Radio networks allow the unlicensed users to share the available spectrum opportunities. However, this demands for solving the problem of contention among multiple unlicensed user packets for transmission. In our paper, we consider the Opportunistic Spectrum Access model for packet transmission between two unlicensed users. We suggest a priority scheme for a unlicensed user to concurrently transmit different types of packets. Our scheme reserves a fixed number of queueing places in the buffer for the prioritized packets. We study the transmission performance under both the priority scheme and imperfect spectrum sensing, with respect to the blocking probabilities, average transmission delay and transmission throughput of unlicensed users packets. The Markov chain based numerical analysis is validated by simulation experiments. Our results show that the suggested priority scheme is able to enhance transmission throughput of unlicensed users packets, together with significant decreased average transmission delay and minor decreased total transmission throughput.

Proactive and Reactive DF Relaying for Cognitive Network with Multiple Primary Users

“…At the same time, the relaying transmission has been demonstrated as an effective means to boost the throughput and extend the coverage of wireless communication system [3][4][5][6]. Hence, investigating the performance of relaying transmission in spectrum sharing system and extension of opportunistic relay selection to cognitive network have attracted great interest [7][8][9][10][11].…”

“…Very recently, the performance of cognitive opportunistic relaying network over frequency selective fading channel has been reported [9]. The joint outage constraint of the PU and peak transmit power constraint of the SU on the outage performance of a cognitive cooperative radio network (CCRN) using the proactive and reactive DF schemes has been investigated in [10]. The outage probability and power allocation for the two-way decode-and-forward (DF) relay network with relay selection has been investigated in [11].…”

“…Furthermore, constraints on primary outage and peak transmit power of SU-Tx or SU relays were not considered simultaneously for multiple PU in early works which are incorporated in our present work. The joint outage constraint of the PU and peak transmit power constraint of the SU on the outage performance of a cognitive cooperative radio network (CCRN) using the proactive and reactive DF schemes has been investigated in [10] for a single PU. In contrast to [10], our present work considers the impact of multiple PUs.…”

“…The joint outage constraint of the PU and peak transmit power constraint of the SU on the outage performance of a cognitive cooperative radio network (CCRN) using the proactive and reactive DF schemes has been investigated in [10] for a single PU. In contrast to [10], our present work considers the impact of multiple PUs. In a realistic scenario more than one PU band may be available.…”

“…Some of them could be unused while others may be occupied depending on PU activity. This feature is captured in our present work while a scenario with a single PU only has been considered in [10]. Moreover, novel closed form expressions for the outage of secondary user in proactive and reactive relay schemes under multiple PUs are derived.…”