Effect Of Channel Estimation Error Research Articles

Effect of Channel Estimation Error on Coordinated Small-Cells with Block Diagonalization

This paper investigates the implementation of cooperative communication in small-cells network. Cooperative communication is some cells that in a network can work together, ex. joint transmit power and exchange resource allocation among them. Therefore, cooperative small-cells can be possible to add more multiple input multiple output (MIMO) antennas. But, channel state information (CSI) is required. In practice, perfect channel state information may not be perfect due to the real condition of the real environment such as delay, error, and etc. This paper illustrates cooperative small-cells under error model on the channel estimation. Our propose system is combined by implementing block diagonalization pre-coding and power allocation based on water-filling algorithm. As investigated by simulation results, our proposed coordinated small-cells showed good performances compare to previous algorithm either with perfect channel or with the error channel estimation.

On the Performance of the Golden Code in the Presence of Channel Estimation Error in Correlated MIMO Rayleigh Fading Channels

AbstractThe Golden Code (GC) is a full-rate and full-diversity, space-time code for 2 × 2 multiple-input multiple-output (MIMO) systems with non-vanishing minimum determinant. Thanks to its algebraic construction, the GC achieves diversity-multiplexing gain trade-off and preserves the mutual information. The zero-forcing (ZF) detection is one of the simplest detection techniques that has a low computational complexity and provides a suboptimal performance. The purpose of this work is to investigate the effect of channel estimation error on the performance of the MIMO-ZF receiver for golden coded systems in spatio-temporally correlated Rayleigh fading channels. An upper and a lower bounds of the error probability are delivered and compared to the Monte Carlo simulation results. We quantify the capacity reduction due to the channel estimation error and to the spatio-temporally correlation. A tight lower bound of the ergodic capacity is provided. Numerical results show an excellent agreement between analytic bounds and Monte Carlo simulation curves. Moreover, the performances of the GC, in terms of bit error rate (BER) and channel capacity, are compared with those of the Alamouti coding.

Virtual Branch Analysis of Symbol Error Rate for OSTBC MIMO Systems with Generalized Selection Combining Using MPSK and MQAM Modulation Schemes

We consider a system where Generalized Selection Combining (GSC) is applied to a 4 x L Multiple-Input Multiple-Output (MIMO) system using Half rate-Full diversity Orthogonal Space-Time Block Codes (OSTBCs) at the transmitter. The Symbol Error Rate (SER) of M-ary Quadrature Amplitude Modulation (MQAM) for a slow, flat Rayleigh fading channel is derived and compared to that of the M-ary Phase Shift Keying (MPSK) modulation scheme. Performance comparisons of various antenna configurations are made. The channel statistics are assumed to be identical for the independent diversity branches. The effects of channel estimation errors on the SER performance for GSC are plotted and discussed in this paper. Index Terms—Multiple-input multiple-output (MIMO) systems, channel estimation error, generalized selection combining (GSC), space-time block codes (STBCs), quadrature amplitude modulation (QAM), symbol error rate (SER).

Realizing high-accuracy transmission in high-rate data broadcasting networks with heterogeneous users via cooperative communication

This paper considers a broadcasting network in which multiple single-antenna (weak) and multiantenna (strong) users are receiving simultaneously spatial-multiplexed data streams from the multiantenna base station (BS). In order to improve the received data quality for the single-antenna users while preserving the transmission rates of the multiantenna users, we propose user cooperation schemes without the employment of space–time codes or retransmission from the BS which reduce the data rates and the spectral efficiency. Three cooperation schemes among single-antenna users, namely, decode-and-forward (DF), amplify-and-forward (AF), and hybrid cooperation, are examined and compared. Simulation results demonstrate that single-antenna users through cooperation can achieve comparable or superior error-rate performance as compared with noncooperative multiantenna users. Various configurations of the proposed cooperation schemes are studied to show the tradeoff in terms of cooperation overhead, receiver complexity, and system performance. The acquisition of the channel information and the effect of channel estimation errors on the system performance are also investigated for practical implementation of the proposed schemes. The proposed schemes are capable of avoiding modification to the multiple-input multiple-output (MIMO) transceivers, and are readily applicable to existing MIMO broadcasting networks.

Effects of Channel Estimation Error on Full-Duplex Two-Way Networks

Bidirectional communication systems based on full-duplex transmission have been proposed as a way to increase the ergodic capacity of multiantenna two-way networks. This type of system enables simultaneous exchange of data between two nodes via bidirectional use of spatial resources. However, when channel estimation error is present, each node experiences both desired-channel interference (DI) and echo-channel interference (EI). This paper investigates the effect of channel estimation errors on the ergodic capacities for bidirectional full-duplex transmission (BFD) using one of two combining schemes: maximal-ratio combining (MRC) or optimum combining (OC). We derive the ergodic capacities as closed-form expressions and quantify the effect of channel estimation errors on ergodic capacities for BFD with MRC (BFD-MRC) or OC (BFD-OC). Numerical results demonstrate that full-duplex transmission in two-way networks is an attractive option when channel estimation error is present.

Optimal Linear Channel Prediction for LTE-A Uplink Under Channel Estimation Errors

This paper proposes an optimal design of the linear channel prediction scheme for LTE-A uplink transmission, taking into account the effect of channel estimation errors. The optimization criterion is to minimize mean square prediction errors, averaged over the distributions of true channel coefficients and estimation errors. We derive a closed-form solution of the optimal channel predictor and provide exact analysis for the achievable mean square error (MSE). The performance gain, in terms of the amount of reduction in MSE, as compared with the conventional channel predictor, is also analytically characterized. Simulation results are used to validate our MSE analyses and to confirm the performance advantage of the proposed solution.

GSVD Beamforming for Two-User MIMO Downlink Channel

This paper introduces the fundamentals of generalized singular value decomposition (GSVD) beamforming: a noniterative beamforming technique based on GSVD for the two-user multiple-input-multiple-output (MIMO) downlink. The numbers of private/common channels produced by GSVD beamforming and transmit power normalization are investigated; the channel gains under Rayleigh fading are characterized exactly for configurations that involve only common channels. Moreover, symbol error rates (SERs) are presented for elementary multicasting and two-way relaying applications; the performance distinctions of the private/common channels and the effect of channel-estimation errors and asymmetries in channel fading are highlighted thereby.

Performance Analysis of Distributed Beamforming in a Spectrum Sharing System

In this paper, we consider a distributed beamforming scheme (DBF) in a spectrum sharing system where multiple secondary users share the spectrum with some licensed primary users under an interference temperature constraint. We assume that the DBF is applied at the secondary users. We first consider optimal beamforming and compare it with the user selection scheme in terms of the outage probability and bit error rate performance metrics. Since perfect feedback is difficult to obtain, we then investigate a limited feedback DBF scheme and develop an analysis for a random vector quantization design algorithm. Specifically, the approximate statistics functions of the squared inner product between the optimal and quantized vectors are derived. With these statistics, we analyze the outage performance. Furthermore, the effects of channel estimation error and number of primary users on the system performance are investigated. Finally, optimal power adaptation and cochannel interference are considered and analyzed. Numerical and simulation results are provided to illustrate our mathematical formalism and verify our analysis.

Robust Transceiver with Tomlinson-Harashima Precoding for Amplify-and-Forward MIMO Relaying Systems

In this paper, robust transceiver design with Tomlinson-Harashima precoding (THP) for multi-hop amplify-and-forward (AF) multiple-input multiple-output (MIMO) relaying systems is investigated. At source node, THP is adopted to mitigate the spatial intersymbol interference. However, due to its nonlinear nature, THP is very sensitive to channel estimation errors. In order to reduce the effects of channel estimation errors, a joint Bayesian robust design of THP at source, linear forwarding matrices at relays and linear equalizer at destination is proposed. With novel applications of elegant characteristics of multiplicative convexity and matrix-monotone functions, the optimal structure of the nonlinear transceiver is first derived. Based on the derived structure, the transceiver design problem reduces to a much simpler one with only scalar variables which can be efficiently solved. Finally, the performance advantage of the proposed robust design over non-robust design is demonstrated by simulation results.

Two-Way Amplify-and-Forward Relaying with Gaussian Imperfect Channel Estimations

In this letter, we study the effect of channel estimation errors on the reception reliability of two-way relaying. For a network with two users that exchange information with each other through multiple amplify-and-forward relays, we investigate a single-relay selection scheme. Since the communication is two-way, the selection scheme aims at optimizing the worse performance of the two communication tasks between the pair of users. The signal-to-noise ratio (SNR) at the users' nodes of the relaying network is formulated and upper bounded. Then, the probability density function (PDF) of the upper bounded SNRs are determined. Subsequently, expressions for the error probabilities are obtained. Furthermore, an approximate PDF of the output instantaneous SNRs are derived, based on which simple and general asymptotic expressions for the error probabilities are presented and discussed. Numerical and simulation results are provided to verify the analysis and compare the performance of the two-way relaying network for different operating conditions and scenarios.

Training and Decodings for Cooperative Network with Multiple Relays and Receive Antennas

In this paper, channel training and coherent decodings under channel estimation error are investigated for relay networks with one single-antenna transmitter, R single-antenna relays, and one R-antenna receiver. A two-stage training scheme is proposed to estimate both the relay-receiver and the transmitter-relay channels at the receiver, which are commonly required in amplify-and-forward (AF) relay networks. We use distributed space-time coding (DSTC) for data transmission and investigate the effect of channel estimation errors on network performance. Two coherent decodings are considered: mismatched decoding in which channel estimations are treated as if perfect, and matched decoding in which estimation error is taken into consideration. We show that for full diversity, with mismatched decoding, at least 3R symbol intervals are required for training; while with matched decoding, R+2 symbol intervals for training are enough. The complexities of the decoding schemes are investigated. To achieve a balance between performance and complexity, an adaptive decoding scheme is proposed. Simulated error rates are shown to justify the analytical results.

Performance of Spatial Modulation in the Presence of Channel Estimation Errors

This work investigates the negative effects of channel estimation errors on the performance of spatial modulation (SM) when operating over flat Rayleigh fading channels. The pairwise error probability of the SM scheme is derived in the presence of channel estimation errors and an upper bound on the average bit error probability is evaluated for M-PSK and M-QAM signalling. It is shown via computer simulations that the derived upper bound becomes very tight with increasing signal-to-noise ratio (SNR) and the SM scheme is quite robust to channel estimation errors.

Robust user pairing algorithm under channel estimation errors for uplink virtual multiple-input multiple-output systems

Employing user pairing schemes in uplink virtual multiple-input multiple-output (V-MIMO) systems can significantly improve system capacity owing to multi-user diversity. Most of the existing user pairing algorithms were developed under the assumption that a scheduler always possesses the perfect channel state information (CSI). In this paper, taking into account the effects of channel estimation error (CEE), the authors propose a robust user pairing algorithm based on a closed-form average sum rate under CEE. In addition, the authors further propose an adaptive user selection scheme as an effort to maximise the sum rates owing to the rate constraint under CEE. The gain of the proposed method is shown in simulation results.

Effect of channel estimation error on performance of time reversal-UWB communication system and its compensation by pre-filter

Time reversal (TR) technique is an effective and simple method for data transmission in extremely multipath indoor ultra-wideband (UWB) channels. Temporal focusing property supported by TR, mitigates the complexity of receiver by reducing the effective channel taps. In spite of its good performance in perfect channel state information (CSI), TR method is very sensitive to the channel estimation error. The effect of channel imperfection on TR technique is considered the study. At first, the bit error rate (BER) of the TR-UWB communication system under the assumptions of the simple matched filter (MF) receiver under the channel estimation errors is derived in closed-form. Then, based on optimal minimum mean square error (MMSE) estimator receiver, a pre-filter is calculated in closed-form to improve the performance of the TR-UWB system in an imperfect CSI scenario. Furthermore, in order to compare the results, similar calculation for pre-filter is carried out based on a simple MF receiver. Unfortunately, it was not possible for us to drive a closed-form solution for pre-filter in this case. To overcome this shortcoming, a two stage iteration-based algorithm is developed at transmitter to calculate a pre-filter in MF receiver. This improved algorithm causes the channel estimation error tends to zero in some steps for the TR-UWB system with MF. The initial value for this iteration-based improved algorithm is considered to be closed-form pre-filter where is calculated based on TR-UWB system with an optimal MMSE estimator. Finally, exhaustive simulations are done to demonstrate the performance advantage attained by the proposed algorithms.

Effects of Channel Estimation Error and Interference on BER in the MIMO Zero-Forcing Receiver

Effects of Channel Estimation Error and Interference on BER in the MIMO Zero-Forcing Receiver

Multi-User Resource Allocation for a Distributed Multi-Carrier DS-CDMA Network

This paper addresses an adaptive multi-user resource allocation for a distributed multi-carrier direct sequence-code division multiple access (MC DS-CDMA) network. The packet throughput, which turns out to be nonconvex and nondifferentiable, is considered to measure the system performance. A sub-optimal non-cooperative power control game is proposed to adaptively allocate the transmit power, available subchannels and alphabet size by minimizing the transmit power with a transmit power constraint and a packet throughput requirement. Also, the paper investigates the effect of channel estimation error on the adaptive resource allocation in a distributed MC DS-CDMA network, and shows that using the Gaussian approximation for the signal-dependent noise can lead to a nontrivial discrepancy in system performance.

Carrier frequency offset tracking for constant modulus signalling-based orthogonal frequency division multiplexing systems

This study presents a blind carrier frequency offset (CFO) tracking algorithm for orthogonal frequency division multiplexing systems with constant modulus signalling. Both single-input single-output and multiple-input multiple-output (MIMO) systems are considered. Based on the assumption that the channel frequency response (CFR) has been estimated by training symbols and keeps constant over one frame duration, we discover that the CFO can be estimated via minimising the power difference between the received signals and the CFR. The polynomial rooting method is exploited to derive a low complexity solution. The expectation and mean-square error of the proposed method are derived mathematically. Besides, the effect of channel estimation error on the performance of CFO tracking is addressed and it is shown that the proposed algorithm is robust to this error. At last, this blind scheme can be applied to a MIMO system with the aid of space time block codes.

Effect of Feedback Delay on the Performance of Cooperative Networks with Relay Selection

In this paper, we analyze the effect of feedback delay and channel estimation errors on the performance of a decode-and-forward (DF) cooperative transmission scenario with relay selection. In our relay selection scheme, only one relay with the best relay-to-destination (R → D) channel quality is selected among the set of relays that decode the source information correctly. Specifically, the destination terminal first estimates the channel state information (CSI) of all active R → D links and then sends the index of the best relay to the relay terminals via a delayed feedback link. Due to the time varying nature of the fading channels, selection is performed based on the old version of the channel estimate. Closed-form expressions for the outage probability, average capacity and average symbol error rate (ASER) are derived. Through asymptotic diversity order analysis, we show that the presence of feedback delay reduces the asymptotic diversity order to one, while the effect of channel estimation errors reduces it to zero. Finally, simulation results are presented to corroborate the analytical results.

Effect of Channel Estimation Error on Time Reversal UWB Communication System

In this paper, effects of channel estimation error on time reversal (TR) UWB systems are investigated. In time reversal, a signal is prefiltered by using a time reversed complex conjugate of the channel impulse response as a transmitter prefilter. To investigate the effect of channel estimation error, an error function is added to TR-UWB prefilter. Analytical and simulation results show that channel estimation error degrade the performance. The signal-to-interference plus noise ratio decreases with increasing error variance. It is shown that the channel performance is degraded about 0.5 dB in CM1 and 1.3 dB in CM4 channel.

Impact of Imperfect Channel State Information on Bi-Directional Communications With Relay Selection

In this correspondence, we study the effect of channel estimation error to the reception reliability for decode-forward based two-way relaying and physical layer network coding. In particular, we focus on the scenario where the channel estimation error is inversely proportional to signal-to-noise ratio (SNR). To such a scenario, analytic results have been developed to show that symbol error probability can approach zero by increasing SNR and extra diversity gains can still be achieved by applying relay selection.