Browsing by Subject "Zero Forcing (ZF),"
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Item MIMO DETECTION SCHEMES FOR WIRELESS COMMUNICATION(Pulchowk Campus, 2012-11) Satyal, SanjivanMultiple Input Multiple Output (MIMO) system is one where multiple antennas are employed at transmitter side as well as receiver side in order to improve the spectral efficiency in wireless communication. Since transmitting side, receiving side and channel, all are responsible for the overall performance in MIMO technology however this thesis focus on MIMO detecting part. Based on the bit error rate, the performance of various detections schemes in Rayleigh and Rician Channel have shown. Different aspects have been considered in the evaluation of performance such as; channel characterization, signal to noise ratio, transmitter and receiver antenna number. From comparative analysis of various detection methods, it is found that Maximum Likelihood has better performance however it has complexity issues with the number of transmitting antenna increased. Hence to mitigate such a problem low complexity detection algorithms such as zero forcing, minimum mean square error detection methods along with Successive Interference Cancellation (SIC) and bell labs layered space time architecture are used to manage complexity. Among these detections algorithm, it is observed that vertical bell labs layered space time with minimum mean square error has optimal solution.Item Ordered Successive Interference Cancellation and Sphere Detection Technique for MIMO(Pulchowk Campus, 2013-09) Adhikari, PrabhatThe advent of multiple inputs, multiple output (MIMO) system has had a major influence on how the current capacity limits of a single antenna system could be increased without the need of overwhelming computational complexity. MIMO systems may be broadly classified into two categories: those designed to increase the transmission rate through spatial multiplexing and those designed to increase reliability using diversity techniques. Most of the current researches are concerned with the spatial multiplexing design scheme as it offers very high increase in data rate. The detection scheme for spatial multiplexing techniques includes linear receivers like Zero Forcing (ZF) and Minimum Mean Square Error (MMSE) and non-linear receivers like Successive Interference Cancellation (SIC), Ordered Successive Interference Cancellation (OSIC) and Sphere Detection (SD). This thesis reviews briefly the MIMO system and the spatial multiplexing technique and compares various detection schemes used in MIMO system. Based on the BER analysis, the performance of various detections schemes in Rayleigh Channel is conducted. Different aspects have been considered in the evaluation of performance namely signal to noise ratio (SNR), modulation order and the number of transmitter and receiver antennas. The Maximum Likelihood (ML) detection method has shown optimum detection for MIMO system however the complexity involved is very high which leads to use of low complexity detection schemes. The performance of linear detection scheme like ZF, MMSE and non-linear schemes like SIC and the OSIC are first reviewed and then a quite new SD algorithm is analyzed where the SD provides near ML solution with much less computational complexity. The obtained results are inter-compared and discussed from different performance aspects.