Ordered Successive Interference Cancellation Algorithm Research Articles

Spatial-Division Multiplexing MIMO Detection Based on a Modified Layered OSIC Scheme

Spatial-division multiplexing (SDM) provides very high spectral efficiency in multiple-input multiple-output (MIMO) systems. A well-known SDM-MIMO wireless system is vertical Bell Labs layered space-time (V-BLAST) which exhibits a good tradeoff between performance and complexity. Although maximum likelihood detection (MLD) has the optimal performance, its complexity is too high to practice such that some alternatives have been studied. The ordered successive interference cancellation (OSIC) algorithm was proposed for the advantage of high feasibility, however, there is a significant performance gap between MLD and OSIC. Here, we propose a modified layered OSIC algorithm to improve symbol detection in ill-conditioned layers with lower complexity compared to exhaustive search methods. To reduce the number of calculating matrix inversion for optimal ordering, we introduce a modified parallel interference cancellation method with precancellation and postcancellation to replace part of successive interference cancellation, based on evaluating the post-detection signal to noise ratio for each layer. Complexity analysis shows that the proposed algorithm saves about 65% operation of matrix inversion compared to a near-optimal improved layered OSIC algorithm while maintaining the similar bit error rate performance as shown in numerical results.

An Efficient Soft-Output MIMO Detection Method Based on a Multiple-Channel-Ordering Technique

In this paper, we propose an efficient soft-output signal detection method for spatially multiplexed multiple-input multiple-output (MIMO) systems. The proposed method is based on the ordered successive interference cancellation (OSIC) algorithm, but it significantly improves the performance of the original OSIC algorithm by solving the error propagation problem. The proposed method combines this enhanced OSIC algorithm with a multiple-channel-ordering technique in a very efficient way. As a result, the log likelihood ratio values can be computed by using a very small set of candidate symbol vectors. The proposed method has been synthesized with a 0.13-μm CMOS technology for a 4×4 16-QAM MIMO system. The simulation and implementation results show that the proposed detector provides a very good solution in terms of performance and hardware complexity.

An efficient algorithm for clustered integer least squares problems

SUMMARYThe integer least squares problem is known to be NP‐hard, and the algorithms such as the sphere decoding algorithm, which give the optimal solution, are usually too slow. To obtain a solution efficiently one may use one of the suboptimal algorithms such as the ordered successive interference cancellation (OSIC) algorithm or the LLL‐aided OSIC algorithm that first modifies the system of equations using the LLL algorithm due to Lenstra, Lenstra, and Lovász. However, these suboptimal algorithms still may not be fast enough depending on the applications. In this paper we present two decoupling techniques to speed‐up the LLL‐aided OSIC algorithm. Our LLL‐aided decoupled OSIC algorithm, which is applicable to clustered integer least squares problems, has the accuracy comparable to the ordinary LLL‐aided OSIC algorithm (without decoupling), but is much faster than the OSIC algorithm or the LLL‐aided OSIC algorithm. Copyright © 2011 John Wiley & Sons, Ltd.

A New Signal Detection Method for Spatially Multiplexed MIMO Systems and Its VLSI Implementation

This brief proposes a new signal detection method called QR ordered successive interference cancellation (OSIC) with candidates (QOC) method for spatially multiplexed multiple-input-multiple-output (MIMO) systems. By using the OSIC algorithm and the maximum-likelihood (ML) metric, the proposed method achieves near-ML performance without requiring a large number of candidates. Although the proposed method can be used for both hard and soft decoding systems, it is particularly useful for soft decoding systems since the log-likelihood-ratio (LLR) values for all the bits can efficiently be computed without using LLR estimation. The proposed method is also suitable for very large scale integration (VLSI) implementation since it leads to a fixed throughput system. A QOC detector for a 4 times4 16-quadrature-amplitude-modulation (16-QAM) MIMO system has been designed and synthesized with a 0.13-mum complimentary metal-oxide-semiconductor (CMOS) technology. The implementation results show that the proposed detector reduces the hardware complexity by 73% relative to a K-best detector.

Threshold-Based OSIC Detection Algorithm for Per-Antenna-Coded TIMO-OFDM Systems

Threshold-based ordered successive interference cancellation (OSIC) detection algorithm is proposed for per-antenna-coded (PAC) two-input multiple-output (TIMO) orthogonal frequency division multiplexing (OFDM) systems. Successive interference cancellation (SIC) is performed selectively according to channel conditions. Compared with the conventional OSIC algorithm, the proposed algorithm reduces the complexity significantly with only a slight performance degradation.