Zero-forcing Successive Interference Cancellation Research Articles

Performance improvement of space diversity technique using space time block coding for time varying channels in wireless environment

Performance improvement of space diversity technique using space time block coding for time varying channels in wireless environment

Generic Deep Learning-Based Linear Detectors for MIMO Systems Over Correlated Noise Environments

To support the and development and application of the fifth-generation (5G) communication and internet of things (IoT) networks, high data-rate wireless transmission is required. To meet the demand of high data-rate, multiple antennas are equipped at the transmitter and receiver, forming multiple-input multiple-output (MIMO) systems. A big challenge of MIMO is the detector design in correlated noise environments, which should achieve a fine performance with moderate computational complexity. To this end, we employ an iterative framework of a deep convolutional neural network (DCNN) and a linear detector for MIMO systems over correlated noise environments. In this framework, the linear detector can be zero-forcing (ZF), minimum mean square error (MMSE), ZF with successive interference cancellation (ZF-SIC), or MMSE-SIC, which produces an initial estimate of transmitted signals. The DCNN is used to capture the local correlation among noise, and it can produce a more accurate estimate of transmitted signals. Simulation results are finally provided to show that the proposed detector can outperform the conventional linear detectors substantially through capturing the local correlation characteristics among noise.

Energy Efficiency of Massive MIMO Systems With Low-Resolution ADCs and Successive Interference Cancellation

This paper studies the influence of signal detection schemes on the energy efficiency (EE) of uplink multiple-input-multiple-output (MIMO) systems with low-resolution analog-to-digital converters (ADCs). Assuming equal transmission rates for all users, we derive the optimal power allocation and their analytical approximations for zero-forcing (ZF) and ZF successive interference cancellation (ZF-SIC) receivers. Both the cases with perfect channel state information (CSI) and with imperfect CSI are considered. The EE with different receivers is compared. The results indicate that for uplink massive MIMO systems with low-resolution ADCs, the radio-frequency circuit power consumption can be significant because a large number of antennas are required to compensate for the loss due to quantization errors while the number of base station antennas needed with the ZF-SIC receiver is significantly smaller than that with the ZF receiver. Meanwhile, the increase of power consumption of signal processing with ZF-SIC can be moderate, due to the fact that the receiver weights are reused in a coherent block and the dimensionality is reduced. Consequently, the ZF-SIC receiver is able to improve the overall EE for massive MIMO systems with practical ADCs. We also conduct an approximation analysis for a multi-cell scenario with the pilot contamination and inter-cell-interference considered.

Analysis of the Alamouti STBC MIMO System With Spatial Division Multiplexing Over the Rayleigh Fading Channel

The Alamouti space-time block coding (STBC) multiple input multiple output (MIMO) system with spatial division multiplexing (SDM) is different from the pure SDM MIMO system in transmitting groups of Alamouti STBC symbols. Because of the Alamouti STBC, the zero-forcing with successive interference cancellation (ZF-SIC) detector for this MIMO system also detects one group of Alamouti STBC symbols in its one iteration. Previous analytical studies on this MIMO system were concentrated on the scenario of only four transmit antennas and did not take full advantage of the group-wise properties of the equivalent channel matrix due to Alamouti STBC. To deliver indepth analysis of this MIMO system with arbitrary number of transmit antennas, the ZF-SIC detection of the groups of Alamouti STBC symbols over the independent identically distributed Rayleigh fading channel is analyzed. Exact average block error probability of detecting all groups of Alamotui STBC symbols and its high signal-to-noise ratio (SNR) approximation are computed. Also, exact average group error probability of detecting each group of Alamotui STBC symbols and its high SNR approximation are computed. These analytical results are shown to agree with the simulation results.

Comparisons of Two Real-Valued MIMO Signal Models and Their Associated ZF-SIC Detectors over the Rayleigh Fading Channel

Two real MIMO models, the new lattice representation and the conventional real model, have been proposed in literature as equivalent models to the same complex MIMO model. To learn which one shares more information with the complex model, we show in this paper that the matrices produced by singular value decomposition and QR-decomposition of the complex and new real channel matrices for the complex and new real models, respectively, are fully related. Also, the new real zero-forcing successive interference cancellation (ZF-SIC) detector is shown to find the same solution as the complex ZF-SIC detector. Comparisons of the two real ZF-SIC detectors based on the two real models are therefore equivalent to the comparisons of the complex and conventional real ZF-SIC detectors. Plenty comparisons of the two real ZF-SIC detectors over the Rayleigh fading channel are reported, including the average joint error probability at finite signal-to-noise ratio (SNR), outage probability at different layers, average error probability at high SNR, and the scenario with optimal transmit power allocation. These comparisons provide much understanding about the complex and two real models as well as their associated detectors.

Multiuser Detection using Zero Forcing Successive Interference Cancellation for WCDMA

performance of the WCDMA system is degraded due to the various network impairments such as interference, fading & noise and also due to network load. The work in this presents performance analysis of zero forcing successive interference cancellation (ZF-SIC) scheme for the multiuser detection in the WCDMA environment. The bit-error rate (BER) of WCDMA using ZF-SIC for binary phase shift keying (BPSK) and quadrature phase shift keying (QPSK) has been analyzed. The ZF-SIC scheme subtracts the strongest received signal from the original one by one till all users have been detected and demodulated. The proposed scheme also suppressed multiple-access interference (MAI) and improved the system performance significantly. The simulation results showed that the BER is decreased the with number of users increased

Multipath Interference Cancellation in MIMO Mobile Cellular system

Wireless network widely used today include, cellular network, wireless mesh network (WMNs), wireless local area network and personal area network. The increasing demand for these networks has turned spectrum into a precious resource. For this reason, there is always a need for methods to pack more bits/Hz. A particular solution is to use multiple antenna at both transmitter and receiver side. Such a system is called multiple-input multiple-output (MIMO) system. In real propagation environment of cellular communication, channel reuse will cause the co-channel interference which will degrade the MIMO channel performance. The interference cancellation (IC technology) can handle efficiently the cochannel interference. In this paper comparison computer simulation for zero forcing successive interference cancellation (ZF-SIC) minimum mean square error (MMSE equalizer) and maximum likelihood (ML) for two transmitting and two receiving antenna is shown.

Uplink Multiple-User V-BLAST Optimal Detection Ordering With Service Differentiation

In this paper, we introduce a new differentiated successive-interference cancellation (DiffSIC) ordering technique for uplink multiple-user systems. Unlike classical successive-interference cancellation (SIC), DiffSIC is capable of differentiating users according to their priority or class of service by selecting a detection order that best fits the users' service profiles. In addition, DiffSIC is able to achieve the optimal SIC detection order that results in the best overall system performance. To develop DiffSIC, we introduce analytical methods toward finding instantaneous symbol error rates (SERs) for zero-forcing SIC (ZF-SIC) and minimum mean square error SIC (MMSE-SIC) detectors. Furthermore, we devise two procedures to reduce the computational complexity associated with the computation of SER and the enumeration of detection orders. We present a number of numerical results that clearly demonstrate the ability of DiffSIC to accomplish service differentiation and overall performance improvement in general.

Performance analysis on MIMO-OFCDM systems with multi-code transmission

This letter proposes an analytical approach to evaluate the performance of MIMO-OFCDM systems with multicode transmission. Assuming zero-forcing successive interference cancellation (ZF-SIC) in the space domain and MMSE detection in the frequency domain, it is shown that at each step of SIC, the error events on multiple code channels are correlated to each other, which make the performance evaluation difficult due to the involvement of a complicated multivariate probability. By approximating the multivariate probability by a series of two-variate probabilities, the proposed analytical approach takes the correlation into account and provides accurate performance estimations. The analytical results are verified by simulations and shown to be more accurate than those where no correlation is considered.

Performance of spatially multiplexed MC-CDM with zero-forcing unified successive interference cancellation detection

Spatially multiplexed multicarrier code-division multiplexing (SM-MC-CDM) is a multiple-input multiple-output, orthogonal frequency division multiplexing (MIMO-OFDM) communication technique with multiple antennas used for spatial multiplexing and with frequency domain spreading on each antenna. Unified successive interference canceller (U-SIC) is an efficient detector recently introduced for SM-MC-CDM. This paper presents an analytical approach to the performance of zero-forcing (ZF) U-SIC for SM-MC-CDM communications. For a system with an equal number of transmit and receive antennas, an approximation for the probability density function of post-detection signal-to-noise ratio (SNR) is used to derive a closed-form analytical upper bound and approximations for the probability of error and ergodic capacity. It is shown that SM-MC-CDM with ZF U-SIC is able to achieve higher diversity order than that achieved by ZF and minimum mean squared error (MMSE) V-BLAST detectors used on each subcarrier of a MIMO-OFDM system with the same number of subcarriers. The diversity order obtained increases with the number of subcarriers. It is also shown that the ergodic capacity of the system decreases with increasing number of subcarriers.

Optimal Power Distribution Control for Multicode MC-CDMA with Zero-Forcing Successive Interference Cancellation

Multicarrier CDMA (MC-CDMA) has become a promising candidate for future wireless multimedia communications for its robustness to frequency-selective fading and its flexibility in handling multiple data rates. Among different multirate access schemes, multicode MC-CDMA is attractive for its high performance, good flexibility in rate matching, and low complexity. However, its performance is limited by self-interference (SI) and multiuser interference (MUI). In this paper, a zero-forcing successive interference cancellation (ZF-SIC) receiver is used to mitigate this problem for multicode MC-CDMA. Furthermore, optimal power distribution control (PDC), which minimizes each user's bit error rate (BER), is considered. Our results show that, in correlated Rayleigh fading channels, the ZF-SIC receiver integrated with the optimal PDC dramatically improves the performance of the multicode MC-CDMA system in comparison with other receivers proposed in the literature. Moreover, the optimal PDC significantly outperforms the PDC based on equal BER criterion, particularly under a short-term transmit power constraint.

Space–Time Power Optimization of Variable-Rate Space–Time Block Codes Based on Successive Interference Cancellation

Based on a zero-forcing with successive interference cancellation (ZFSIC) method, we construct variable-rate space-time block codes (STBCs) for two, three, and four transmit antennas in Rayleigh fading channels. Considering the error-propagation effect in the ZFSIC scheme, we analyze the bit-error rate (BER) and optimize the transmit power so that the average BER is minimized. Unlike the approach based on zero-forcing (ZF), the method adopted in this paper can construct variable-rate STBCs even when the receive antennas are fewer than the transmit antennas. In addition, to improve the BERs further, we propose space-time power optimization. Numerical results show that the codes presented in this paper provide much lower BERs, compared with the codes developed by Kim and Tarokh.

Low complexity per-antenna rate and power control approach for closed-loop V-BLAST

Previous studies have shown that per-antenna rate and power control can greatly increase the data throughput of vertical Bell Labs layered space-time (V-BLAST), while an extra transmit antenna selection can provide additional diversity advantage. We combine the transmit antenna selection with power and rate control for each antenna. We derive a simple criterion for minimum bit-error rate (BER) or minimum total transmit power when the data throughput is constant over time. Zero-forcing and zero-forcing successive interference cancellation detections are considered. For practical implementation, we also present a fast algorithm that gives near-optimal performance with very low complexity. Simulation results show that the proposed closed-loop BLAST outperforms the open-loop V-BLAST significantly in terms of BER performance, especially when the antennas exhibit strong fading correlations.