Abstract
The use of multiple antennas at the transmitter as well as at the receiver can greatly improve the capacity of a wireless link when operating in a rich scattering environment. In such an arrangement all transmitting antennas radiate in the same frequency band so the overall spectral efficiency becomes very high. Such a multiple antenna scheme, popularly known as Multiple Input Multiple Output (MIMO) has potential application in Wireless Local Area Networks (WLAN) and cellular micro-cells. One reason is that the WLANs and other short range wireless systems often operate in an indoor environment, which offers rich scattering. The other reason is the demand for higher data rates in cellular and WLAN systems to scater for multimedia services. Also to meet the requirement of very high data rates for wireless Internet and multimedia services, multiple transmitting and multiple receiving antennas have been proposed for fourth generation wireless systems. In cellular systems, performance is limited by fading and co channel interference from other users. Most of the current studies on Multiple-Input Multiple-Output (MIMO) systems assume that the co-channel interference is both spatially and temporally white. Recently researchers have proposed different architectures for materializing the potential of the MIMO scheme. We consider three different types of channels: AWGN, Rician fading and Rayleigh fading. The entire work will be simulated in the Monti Carlo simulations. The main contribution of this study includes: A comparative study and a head to head comparison of the different modulation types based MIMO systems. The application of adaptive modulation in the MIMO system will be considered.
Highlights
The major impairments of the wireless channel are fading and co-channel interference
The other reason is the demand for higher data rates in cellular and Wireless Local Area Networks (WLAN) systems to scater for multimedia services
The modulation schemes as BPSK, QPSK, 16-square Quadrature Amplitude Modulation (QAM), has a spectral efficiency of a Multiple-Input Multiple-Output (MIMO) system is expressed in terms of data rate per unit bandwidth in bits/sec/Hz
Summary
The major impairments of the wireless channel are fading and co-channel interference. Transmit diversity was first introduced by in (Wittneben, 1993) and by space-time codes (Tarokh et al, 1998) This a similar principle to the receiver-based beam forming, if the channel information of the desired and co-channel users is available at the transmitter, transmit beam forming can be used to enhance the Signal-to-Noise Ratio (SNR) for the intended user and minimize the interference energy sent towards co channel users (Rashid-Farrokhi et al, 1998; Lozano et al, 2001). Multicarrier techniques especially Orthogonal Frequency Division Multiplexing (OFDM) has been used as a modulation scheme that can achieve high data rate by efficiently handling multipath effects. This is reflected by the many standards that considered and adopted OFDM, including those for Digital Audio and Video Broadcasting (DAB and DVB). Another type of blind channel estimator capitalizes on the finite alphabet property of the modulated symbols (Hui et al, 2004)
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