Energy‐efficient outage‐constrained power allocation based on statistical channel knowledge for dual‐hop cognitive relay networks

Abstract

This paper investigates the power allocation problem in decode-and-forward cognitive dual-hop systems over Rayleigh fading channels. In order to optimize the performance of the secondary network in terms of power consumption, an outage-constrained power allocation scheme is proposed. The secondary nodes adjust their transmit power subject to an average interference constraint at the primary receiver and an outage probability constraint for the secondary receivers while having only statistical channel knowledge with respect to the primary nodes. We compare this approach with a power allocation scheme based on instantaneous channel state information under a peak interference constraint. Analytical and numerical results show that the proposed approach, without requiring the constant interchange of channel state information, can achieve a similar performance in terms of outage probability as that of power allocation based on instantaneous channel knowledge. Moreover, the transmit power allocated by the proposed approach is considerably smaller than the power allocated by the method based on instantaneous channel knowledge in more than 50% of the time.perspective [11] but also from the economic point of view. Therefore, minimizing the energy consumption for wireless data transmission becomes one of the most important design goals in WSNs, aiming at maximizing the battery lifetime. Because the transmit power is a relevant fraction of the total consumed energy, power allocation (PA) plays an important role towards achieving the aforementioned goal. Related worksSeveral recent works investigate the outage behavior of cooperative cognitive networks under different relaying protocols, number of available relays, channel models, and interference conditions, as for instance, [12][13][14][15][16][17][18]. In [12], it is investigated the outage performance of a multi-relay network under Rayleigh fading channels in a noise-limited environment, as well as the impact of imperfect channel state information (CSI) on the system performance. The authors in [13] carry out an analysis about the capacity and outage behavior of a decode-and-forward (DF) dual-hop system in a scenario where the SUs are subject to interference imposed by the PU. Similar to [13], the presence of PU interference is also considered in [14], but the authors show that increasing the number of relays can compensate the performance degradation caused by the PU interference. The diversity order and outage performance of a single relay dual-hop system in a noise-limited scenario under Nakagamim fading are investigated in [15]. Considering the presence of multiple primary transmitters (PTs) and receivers, the outage performance of DF systems is evaluated in [16]. In all these works, the transmit power of the SUs is adjusted to its maximum allowed value such that the peak interference at the primary receiver (PR) remains below the required constraint. However, this approach requires global CSI at the secondary network, of all the related channel coefficients, but perf...

Error rate and outage of dual‐hop DF relay system with selection combining over Rice fading

“…There are many research works available on the decode‐and‐forward (DF) relay systems over fading channels. The works in line with the perspective of the analysis presented here are from the previous studies . The works in Su et al, Lee and Tsai, and Kim and Beaulieu present average symbol error rate (ASER) expressions for digital modulation schemes using MRC receiver for dual‐hop transmission over Nakagami‐ m fading channels while also applies optimal power allocation scheme in its analysis.…”

“…The outage probability over mixed Rayleigh and generalized gamma fading channels is derived in Kapucu et al A performance comparison of dual‐hop hybrid decode‐or‐amplify‐forward relay schemes over Rayleigh fading channels is presented in Woo et al Kapucu et al investigate ABER performance of direct‐sequence code division multiple access scheme on dual‐hop amplify‐and‐forward protocol over different fading channels. A outage‐constrained power allocation for dual‐hop cognitive relay system is studied in Bordon et al In Anees and Bhatnagar, a performance analysis for DF dual‐hop asymmetric radio frequency free space optical communication system is presented. Authors analyze performance of dual‐hop DF relaying over mixed η − μ and κ − μ fading channels in Chaitanya and Muthuchidambaranathan .…”

Optimal power allocation for energy‐efficient full‐duplex cognitive relay networks under primary interference

“…Motivated by the need to improve the EE, several authors have recently made attempts to analyse the EE of CRNs, see e.g. [12–22] and references therein. In [12, 13], the authors have independently investigated the optimal power allocation (OPA) scheme for improving the EE of decode‐and‐forward (DF)‐based dual‐hop CRN.…”

“…Zhang et al [15] have investigated two distinct problems for a dual‐hop CRN with the following objectives: (i) minimise the transmit power to reduce energy consumption, and (ii) maximise the transmission rate of the secondary network. In [16], the authors have considered optimising the power consumption of secondary network in dual‐hop CRN subject to an average interference constraint at the primary receiver and an outage probability constraint for the secondary receivers. In [17], the authors have addressed a residual energy maximisation problem for a two‐hop DF relay‐assisted CRN operating in a time‐slotted mode in the presence of an eavesdropper.…”