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Please use this identifier to cite or link to this item: http://hdl.handle.net/123456789/2293

Title: Low Complexity MIMOെOFDM Receivers for Achieving Near Optimal Performance
Authors: Nadew, Adisu
Advisors: Dr.-Ing Hailu Ayele
Keywords: Hybrid Sphere Decoding
Sphere Decoding Algorithms
MIMOെOFDM Signal Detection
Copyright: Jul-2011
Date Added: 3-May-2012
Publisher: AAU
Abstract: Since the useable frequency spectrum is a scarce resource, future wireless systems should focus on new technologies that provide high spectral efficiency and improved link reliability. The combination of MultipleെInput MultipleെOutput (MIMO) wireless communication with Orthogonal Frequency Division Multiplexing (OFDM) is a very promising technology to meet these requirements. Although MIMOെOFDM systems have demonstrated very high spectral efficiency, the available capacities of these systems are not fully exploited due to lack of low complex and, at the same time, optimal signal detection scheme. To this end, after reviewing the available detection techniques, this thesis proposes a low complex MIMO signal detection technique which has near optimal performance. It is found that among the MIMO signal detection techniques the Maximum Likelihood Decoding (MLD) has optimal performance; however, the corresponding computational complexity grows exponentially with the number of antennas and/or constellation size. The conventional detection schemes such as ZF, MMSE, ZF with SIC and MMSE with SIC have relatively manageable complexity; however, in general their BER performance is poor especially for large MIMO sizes. The sphere decoding algorithms (SDAs), specifically the depth first sphere decoding (DF SD), achieves similar performance to MLD at relatively reasonable complexity, but it has very large variation of computational throughput. In order to reduce the complexity of DF SD, initial radius setting strategy is introduced in this thesis and, with this, enormous computational complexity is saved. Fixed throughput SDAs, namely kെbest SDAs, are also analyzed and as a result, it is obtained that these schemes have performance degradation compared to the MLD. So, a hybrid sphere decoding which combines the desirable features of the two SDAs is proposed in this thesis and simulation results show that the proposed scheme can achieve performance very close to the MLD at very high computational throughput which is more than twice of that of kെbest SDAs.
URI: http://hdl.handle.net/123456789/2293
Appears in:Thesis - Computer Engineering

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