Area spectral efficiency of soft-decision space–time–frequency shift-keying-aided slow-frequency-hopping multiple access

Slow-frequency-hopping multiple access (SFHMA) can provide inherent frequency diversity and beneficially randomize the effects of cochannel interference. It may also be advantageously combined with our novel space-time–frequency shift keying (STFSK) scheme. The proposed system’s area spectral efficiency is investigated in various cellular frequency reuse structures. Furthermore, it is compared to both classic Gaussian minimum shift keying (GMSK)-aided SFHMA and GMSK-assisted time- division/frequency-division multiple access (TD/FDMA). The more sophisticated third-generation wideband code-division multiple access (WCDMA) and the fourth-generation Long Term Evolution (LTE) systems were also included in our comparisons. We demonstrate that the area spectral efficiency of the STFSK-aided SFHMA system is higher than the GMSK-aided SFHMA and TD/FDMA systems, as well as WCDMA, but it is only 60% of the LTE system

Performance Enhancement in SU and MU MIMO-OFDM Technique for Wireless Communication: A Review

The consistent demand for higher data rates and need to send giant volumes of data while not compromising the quality of communication has led the development of a new generations of wireless systems. But range and data rate limitations are there in wireless devices. In an attempt to beat these limitations, Multi Input Multi Output (MIMO) systems will be used which also increase diversity and improve the bit error rate (BER) performance of wireless systems. They additionally increase the channel capacity, increase the transmitted data rate through spatial multiplexing, and/or reduce interference from other users. MIMO systems therefore create a promising communication system because of their high transmission rates without additional bandwidth or transmit power and robustness against multipath fading. This paper provides the overview of Multiuser MIMO system. A detailed review on how to increase performance of system and reduce the bit error rate (BER) in different fading environment e.g. Rayleigh fading, Rician fading, Nakagami fading, composite fading

Positive Effect of Severe Nakagami- m

This paper investigates the positive effect of severe Nakagami-m fading on the performance of multiuser transmit antenna selection/maximal-ratio combining (TAS/MRC) systems with high selection gain. Both amount of fading (AF) and symbol error rate (SER) of M-QAM are derived as closed-form expressions for integer m. For arbitrary m, the AF and the SER are expressible as a single infinite series of Gamma function and Gauss hypergeometric function, respectively. The analytical results lead to the following observations. First, the SER performance can demonstrate the positive effect of severe Nakagami-m fading on multiuser TAS/MRC systems with high selection gain. Second, the AF performance only exhibits the negative impact of severe fading regardless of high selection gain. Last, the benefit of severe fading to the system performance diminishes at high signal-to-noise ratio (SNR)