Low Complexity MIMO-OFDM Receivers for Achieving Near Optimal Performance

Adisu, Nadew (2011) Low Complexity MIMO-OFDM Receivers for Achieving Near Optimal Performance. Masters thesis, Addis Ababa University.

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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 Multiple-Input Multiple-Output (MIMO) wireless communication with Orthogonal Frequency Division Multiplexing (OFDM) is a very promising technology to meet these requirements. Although MIMO-OFDM 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 k-best 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 k-best SDAs.

Item Type: Thesis (Masters)
Uncontrolled Keywords: MIMO-OFDM Signal Detection, Sphere Decoding Algorithms, Hybrid Sphere Decoding
Subjects: H Social Sciences > HE Transportation and Communications
Q Science > QA Mathematics
Q Science > QA Mathematics > QA75 Electronic computers. Computer science
T Technology > T Technology (General)
T Technology > TK Electrical engineering. Electronics Nuclear engineering
Divisions: Africana
Depositing User: Andriamparany Edilbert RANOARIVONY
Date Deposited: 13 Jul 2018 09:08
Last Modified: 13 Jul 2018 09:08
URI: http://thesisbank.jhia.ac.ke/id/eprint/7391

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