Mimo

ABSTRACT

MIMO-OFDM is a new wireless broadband technology, has gained great popularity for its capability of high rate transmission and its robustness against multi-path fading and other channel impairments. This project investigates the application of independent component analysis algorithm on MIMO OFDM systems. Here a comparison of bit error rate performance of MIMO OFDM systems utilising ICA algorithm and that of ordinary OFDM systems is carried out. This shows a considerable increase in BER performance of the system. First we analysed in conventional OFDM system utilising cyclic prefix, which converts a frequency selective channel into a number of flat fading channels. Here the error probability on each sub carrier is very high, and dominates BER of the total system for high SNR. When MIMO concept is taken into account, it faces a drawback that inter carrier interference is highly dominating due to mixing up of the signals. In ICA algorithm, a pre-processing step is done which consists of two phases namely centring is done by subtracting its mean vector to make it as a zero random variable and whitening is done by transforming observed variable to obtain a new vector. Then it is accomplished by feature extraction process whereby the original information is obtained by eliminating extra redundant information. This shows an increased performance of MIMO OFDM systems.

LIST OF TABLES

TABLE NO. TITLE PAGE NO.

5.1 Examples of Modulating random functions 51

A1 Merits and demerits of various digital

Modulation techniques 57

A2 Performance characteristics of digital

Modulation techniques 59

LIST OF FIGURES

FIGURE NO. TITLE PAGE NO.

3.1 Difference between OFDM and

Conventional FDM 23

3.2 OFDM Spectrum form 23

3.3 OFDM Transmission and Reception 25

3.4 Cyclic prefix with guard time 27

3.5 Nt × Nr MIMO model 29

3.6 Cock tail problem 32

4.1 Concept...