Performance Analysis of K-Best Sphere Decoder Algorithm for Spatial Multiplexing MIMO Systems Umamaheshwar Soma1 , Anil Kumar Tipparti 2 , Srinivasa Rao Kunupalli 3 1 Department of Electronics and Communication Engineering, SR Engineering College,Warangal, Telangana, India 2 Department of Electronics and Communication Engineering, MVSR Engineering College, Hydeerabad, Telangana, India 3 Department of Electronics and Communication Engineering, TRR College of Engineering Hyderabad, Telangana, India 1 umamaheshwarsoma@rediffmail.com, 2 tvakumar2000@yahoo.co.in, 3 principaltrr@gmail.com Abstract Recently, soft iterative decoding techniques have been shown to greatly improve the bit error rate (BER) performance of various communication systems. For multi-antenna systems employing space-time codes (STC), however, it is not the best way to obtain the soft information required for the iterative receiver’s with low complexity.In this paper, we analyzed several MIMO detection schemes under various channel conditions with different modulation schemes and compare their performance. Finally, we proposed a low complexity K-best sphere decoding algorithm, which achieves near ML performance with very much reduced computational complexity. Key Words: Fixed sphere decoder; Iterative detectors; K-Best SD; LC-K-Best SD; Spatial Multiplexing 1 Introduction Recently, the pursuit of high-speed wireless data services has generated a significant amount of activity in the communications research community. The physical limitations of the wireless channel present many challenges to the design of high-rate reliable communication systems. Multi-antenna wireless communication systems are capable of providing data transmission at potentially very high rates [1]. In multi-antenna systems, space-time [2-3] codes are often employed at the transmitter to induce diversity. A low-complexity detection scheme for multi-antenna systems in a fading environment has been studied [3]. This detection scheme is depends on the adopted criterion essentially performs zero-forcing or minimum-mean-square-error decision feedback equalization on block transmissions. The sphere decoder provides the maximum-likelihood (ML) estimate of the transmitted signal sequence and so often significantly outperforms heuristic nulling and cancelling. Moreover, it was generally believed that sphere decoding requires much greater computational complexity than the cubic-time nulling and cancelling techniques The iterative processing for MIMO-OFDM systems is still very much evolving in order to find a best trade off between performance and complexity for the future wireless communication. The main objective of this paper is to address the above challenges involved by the iterative receiver combining MIMO detection. Therefore, an advanced receiver must be developed at algorithmic and architectural levels that must be able to achieve near optimal performance with an acceptable computational complexity. The receiver must also satisfy high throughput, low latency and low power consumption requirements for wireless communication systems. The main contributions of this paper can be summarized as follows: Based on literature, we studied and analyzed the soft-input soft-output (SISO) detection algorithms for iterative MIMO receivers. The low complexity K-Best decoder (LC-K-Best) is proposed for the sake of low computational complexity and low latency without significant performance degradation. Compared the performance and complexity of LC-K-Best decoder and existing MIMO detection algorithms with different configurations, modulation orders. 2. 1. International Journal of Pure and Applied Mathematics Volume 114 No. 10 2017, 97-107 ISSN: 1311-8080 (printed version); ISSN: 1314-3395 (on-line version) url: http://www.ijpam.eu Special Issue ijpam.eu 97