Exact Outage Analysis of Underlay Cooperative Cognitive Networks with Reactive Relay Selection Under Imperfect Channel Information

Abstract

This paper investigates the effect of imperfect channel information on the outage performance of underlay cooperative cognitive networks with reactive relay selection under both primary outage constraint and maximum transmit power constraint. Towards this end, we firstly propose a power allocation scheme for secondary users to meet both constraints and take into account channel estimation error. Then, based on this scheme we propose an exact closed-form outage probability expression for secondary networks. This expression facilitates in quickly assessing the performance behaviour of underlay cooperative cognitive networks with reactive relay selection in different aspects and provides useful insights into the system performance. Various results show considerable system performance degradation due to imperfect channel information, a performance trade-off between the secondary network and the primary network, the performance saturation phenomenon in the secondary network, and the significant performance improvement with respect to the increase in the number of relays.

Joint Spatial-Temporal Access Scheme for Multihop Cognitive Relay Networks Over Nakagami-m Fading

“…where the first term is calculated as the same as (8) and the second term is calculated by submitting I p Ps into the CDF of g ri as given in (12). Finally, by substituting (14) and (15) into (11) and doing a series of algebraic operations, we obtain (10) and complete the proof.…”

“…Under the interference constraint from one primary receiver (PR), the outage performance of CRNs with single-relay over Gaussian and Nakagami-m fading channels is analyzed in [6,7], respectively. Furthermore, the outage probabilities of CRNs with multi-relay over Rayleigh and Nakagami-m fading are derived in [8,9], respectively. However, all these works [6][7][8][9] assume that the primary transmitter (PT) is far way from CUs in order to ignore its transmission impact on CUs.…”

“…Furthermore, the outage probabilities of CRNs with multi-relay over Rayleigh and Nakagami-m fading are derived in [8,9], respectively. However, all these works [6][7][8][9] assume that the primary transmitter (PT) is far way from CUs in order to ignore its transmission impact on CUs. Thus, with the consideration of PT's interference, the exact and asymptotic outage probabilities of CRNs with single-relay over Rayleigh fading are derived in [10].…”

“…Different from [6][7][8][9][10][11] that focus on the underlay CRNs with only one source-destination pair and with single-relay or multi-relay, the following works pay attention to the case of CRNs with multi-destination over Nakagami-m fading. Specifically, without the consideration of PT's interference, the outage performances of CRNs with single-relay under the interference constraints from multiple PRs, and with multi-relay under the interference constraint from one PR are investigated in [12,13], respectively.…”

“…In addition to the above works [3][4][5][6][7][8][9][10][11][12][13][14] that focus on dual-hop CRNs, a more general scenario of multihop CRNs is receiving more attention, since multihop relaying is an efficient strategy to save power, and improve connectivity or coverage. In [15], under the interference constraint from one PR, the outage performance of multihop CRNs with imperfect channel state information (CSI) over Nakagami-m fading is investigated.…”