Impact of imperfect channel estimation on the performance of amplify-and-forward relaying

Abstract

Abstract-In this paper, we investigate the error rate performance of amplify-and-forward (AF) relaying with imperfect channel estimation. We consider a single-relay scenario with orthogonal and non-orthogonal AF (OAF and NAF) cooperative protocols. Two pilot-symbol-assisted receiver architectures are studied: In the mismatched-coherent receiver, the complex fading channel coefficients (i.e., both phase and amplitude) are estimated based on a linear minimum-mean-squared-error estimation approach and fed to a coherent sub-optimal maximum likelihood decoder as if the channels were perfectly known. In the partiallycoherent receiver, channel amplitude is ignored and phase is estimated by a phase locked loop. For both receiver types, we analyze the achievable diversity orders for cooperative protocols under consideration and quantify the impact of channel estimation through the derivation of pairwise error probability. Our performance analysis reveals that a second order diversity order is obtained for the considered single-relay scenario indicating that full diversity is extracted. Our simulation results demonstrate that the performance degradation due to channel estimation with respect to the genie bound (i.e., perfect channel state information) is as small as 1.1dB based on the employed detector. Performance results further show that partially-coherent receiver presents a similar performance to mismatched-receiver for sufficiently large loop SNRs although channel amplitude is completely ignored.

Simultaneous estimation of multi-relay MIMO channels

“…Similar to previous work in the literature, e.g., [10], the variance, σ 2 , is assumed to be known at the receiver. Assumption A3 is used in previous channel estimation analyses [8]- [10], [15], [16]. Moreover, A3 is justifiable if applied to orthogonal frequency division multiplexing (OFDM) systems, which are used to combat frequency-selective fading in modern wireless systems.…”

Impact of Channel Estimation Errors in Cooperative Transmission over Nakagami-m Fading Channels

“…Then MGF can be given as (13) Similar to getting the SER at the relay node, with the help of Table 1, for one symbol and a specific relay set C R , the average error probability is…”

“…The composite channel estimation means that the overall channel from the source to the destination is estimated at the destination. In [13], considering mismatched-coherent and partially-coherent receivers at the destination terminal, pairwise error probability (PEP) expressions under imperfect channel estimation in AF relaying systems were derived. The SNR expression was derived in [14] with three different approximate assumptions and the outage probability was obtained for a fixed gain AF system in the presence of channel estimation errors.…”

“…Yi Wu and Pätzold in [16] and [17] gave an accurate symbol-error-rate (SER) expression for variable-gain AF cooperative communication systems, although an iterated integral was still involved. Besides, the works in [13]- [17] were limited for a single relay scenario. During the time of the review process of this paper, there are some new-issued researches on this topic for multi-relay cases.…”

Channels and Parameters Acquisition in Cooperative OFDM Systems

“…Nevertheless, to exploit the full potential of cooperative communication accurate estimates for the different links are required. Although some work has evaluated the impact of the imperfect channel estimation in cooperative schemes (Chen et al, 2009), (Fouillot et al, 2010), (Gedik & Uysal, 2009), (Hadizadeh & Muhaidat, 2010), (Han et al, 2009), (Ikki et al 2010), (Muhaidat et al, 2009), new techniques have been derived to address the specificities of such systems. Channel estimation for cooperative communication depends on the employed relaying protocol, e.g., decode and forward (DF) (Laneman et al, 2004) when the relay has the capability to regenerate and re-encode the whole frame; amplify and forward (AF) (Laneman et al, 2004) where only amplification takes place; and what we term equalize and forward (EF) (Moco et al, 2010), (Teodoro et al, 2009), where more sophisticated filtering operations are used.…”