Asymptotic BER Analysis of Threshold Digital Relaying Schemes in Cooperative Wireless Systems

Abstract

Abstract-Threshold relaying is an effective technique to achieve cooperative diversity in uncoded cooperative wireless networks, which suffer from error propagation due to detection errors at the relays. This paper analyzes the asymptotic end-toend (e2e) bit error rate (BER) of threshold digital relaying. A three node network with a source, destination and relay and with links experiencing independent Rayleigh fading is considered. It is shown that, as the average link signal-to-noise ratios (SNR) are increased simultaneously, the optimal threshold that minimizes the e2e BER increases as log(SNR). The resulting e2e BER decreases as log(SNR)/SNR 2 . Moreover, any threshold of the form log(c SNR), where c is a positive constant, achieves the same order of e2e BER as the one achieved by the optimal threshold and provides dual diversity. A value of c that performs very close to the optimal threshold is also proposed.Index Terms-Cooperative diversity relaying, threshold maximum ratio combining, diversity order, selective digital relaying, SNR based selective relaying, multihop communication.

Selective combining for hybrid cooperative networks

“…(16), and the SNR threshold of [42], i.e., Eq. (12). It can be observed that our proposed SNR threshold converges to the optimal SNR threshold at medium and high SNR regimes quickly, which validates our analysis in Section III.…”

A novel threshold-based quadrature signaling scheme for cooperative networks

“…Furthermore, from Figures 3 and 4, we find that numerical and simulation results match very well. Finally, in order to show more features of the TQS scheme, a comparison with the traditional TDR scheme discussed in [8][9][10][11][12] is presented in Figure 5. Without loss of generality, the relevant parameters are set as dSNR = 10 dB, SNR BD = 15 dB, and SNR AD varying from 0 to 30 dB.…”

“…In fact, seeking a higher system performance with a lower implementation complexity is always an important direction of the people's efforts in nowadays we put more emphasis on green communications [6,7]. Particularly, the so-called threshold digital relaying (TDR) cooperative idea, in which the partner(s) decide whether or not to relay the source's signal based on the comparison between the received symbol strength and a predefined threshold, has attracted much attention as it can obtain the diversity gain and provide the implementation simplicity at the same time [8][9][10][11][12]. However, the major disadvantage of the TDR cooperative scheme lies in the two-phase transmission property resulted from its design philosophy.…”

Signal transmission with unequal error protection in relay selection networks

“…Since the average SNR changes much slower compared to the instantaneous SNR, the transmission of the optimal thresholds to the relay if found centrally should not be a major issue in the proposed scheme. 3 With two positive real functions f (x) and g(x), we say f (x) = O(g(x))…”

“…When the sourcerelay SNR is larger than a threshold, the probability of decoding error at the relay can be negligible and hence the relay retransmits the message [1]. For this approach, references [2], [3] derive the optimal threshold value for BPSK modulation to minimize the end-to-end (e2e) BER.…”