Performance Of Diversity Schemes Research Articles

Outage probability comparisons for diversity systems with cochannel interference in Rayleigh fading

Space diversity is an effective method to combat fading and cochannel interference (CCI) in wireless systems. In this paper, outage performances of several diversity schemes, including a practical variation of maximal-ratio combining that does not require signal-to-noise ratios at different antennas, equal-gain combining, and selection combining, are compared analytically for an interference-limited environment in a Rayleigh fading channel. Our analysis provides insight into the performance of diversity schemes in the presence of CCI as well as assesses the impact of cochannel interferer power distributions.

THE PERFORMANCE OF POLARIZATION DIVERSITY SCHEMES IN OUTDOOR MICRO CELLS

The application of polarization diversity reception at the mobile terminal in micro cells at 2 GHz is presented in this paper. Raytracing tool is used to study effects of electric field polarization on the received power in outdoor environments. The performance of diversity schemes with vertical/ horizontal polarization and +45◦/−45◦ slanted polarization are compared in different line-of-sight (LOS) and nonlineof-sight (NLOS) environments. Based on the evaluation of cross polarization discrimination (XPD) parameters, it is clarified that different environments will affect XPD values in micro cells. Then, the vertical/horizontal polarization diversity and +45◦/− 45◦ slanted polarization diversity are chosen to compare with space diversity. Several different combining techniques of polarization and space diversity schemes are also compared in different environments. It is found that dual-polarized antennas for mobile terminal are a promising alternative for two spaced antennas.

Performance of diversity schemes for OFDM systems with frequency offset, phase noise, and channel estimation errors

We provide expressions for the bit error rate of various transmit and receive diversity schemes for orthogonal frequency division multiplexing (OFDM) systems in the presence of frequency offset, phase noise, and channel estimation errors. The derivations are also applicable for a general multiplicative distortion of the received signal. Our results show that with perfect channel estimates, practical values of the phase noise do not significantly degrade the performance of the various diversity methods for binary phase-shift keying modulation. In contrast, the transmit diversity schemes for OFDM are much more sensitive to channel estimation errors than maximal ratio combining receive diversity.