Pilot Optimization and Power Allocation for OFDM-Based Full-Duplex Relay Networks With IQ-Imbalances

Abstract

In OFDM relay networks with IQ imbalances and full-duplex relay station (RS), how to optimize pilot pattern and power allocation using the criterion of minimizing the sum of mean square errors (Sum-MSE) for the frequency-domain leastsquares channel estimator has a heavy impact on self-interference cancellation. Firstly, the design problem of pilot pattern is casted as a convex optimization. From the KKT conditions, the optimal analytical expression is derived given the fixed source power and RS power. Subsequently, an optimal power allocation (OPA) strategy is proposed and presented to further alleviate the effect of Sum-MSE under the total transmit power sum constraint of source node and RS. Simulation results show that the proposed OPA performs better than equal power allocation (EPA) in terms of Sum-MSE, and the Sum-MSE performance gain grows with deviating ρ from the value of ρ o minimizing the Sum-MSE, where ρ is defined as the average ratio of the residual SI channel at RS to the intended channel from source to RS. For example, the OPA achieves about 5dB SNR gain over EPA by shrinking or stretching ρ with a factor 4. More importantly, as ρ decreases or increases more, the performance gain becomes more significant.

Efficient pilot design scheme for OFDM‐based full‐duplex systems

“…It is valuable to investigate the pilot scheme for the FD systems. For FD point‐to‐point OFDM systems with IQ imbalances, channel estimation and pilot optimisation were intensively investigated in [10–12]. In [10], an adaptive orthogonal matching pursuit‐based channel estimator was proposed by exploiting the sparsity of both SI and intended channels mixed with IQ parameters.…”

“…When the transmit power of source was identical with that of destination, the closed‐form expression of optimal pilot product matrix was proved to be any four columns of an unitary matrix multiplied by a constant. This result is extended to the FD relay networks in [12]. However, such a scheme cannot provide satisfactory performance in all cases, since the channel is assumed to be constant during multiple continuous pilot or data OFDM symbols [11, 12].…”

“…This result is extended to the FD relay networks in [12]. However, such a scheme cannot provide satisfactory performance in all cases, since the channel is assumed to be constant during multiple continuous pilot or data OFDM symbols [11, 12].…”

Power Allocation and Capacity Analysis for FBMC-OQAM With Superimposed Training

“…division multiplexing (OFDM) [6], [7] as their multicarrier transmission waveform. While OFDM offers robustness against multipath fading and convenience for a one-tap equalizer implementation, this is achieved at the expense of the efficiency of the entire system.…”

Design and Optimization for Distributed Compress-and-Forward System based on Multi-Relay Network

“…In addition, wireless relay technology has also been studied from other aspects, such as outage probability [11] [12], relay selection [13]- [15], minimizing the bit error ratio (BER) [16] [17] and spatial channel pairing strategy [18]. It should be noted that power allocation has long been playing an important role in wireless relay technology [3] [5], [19]- [22], since a better system performance can be achieved by appropriately allocating limited power between the source and relays.…”