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Coding Techniques to Improve Bit Error Rate in Orthogonal Frequency Division Multiplexing System
Published in Rajeshree Raut, Ranjit Sawant, Shriraghavan Madbushi, Cognitive Radio, 2020
Rajeshree Raut, Ranjit Sawant, Shriraghavan Madbushi
Real-time implementation of MIMO-based OFDM systems has shown that increased capacity, coverage, and reliability can be obtained practically with the use of the MIMO OFDM architecture [4]. Usually, MIMOs can be combined with any type of wireless communication standard; however, in practice, there is a significant performance enhancement of MIMO-aided OFDM over the non-MIMO OFDM technique. Capacity and coverage is improved with the help of beam forming MIMO OFDM communication systems, and it has already been tested under various extreme channel conditions. Smart antenna techniques, which use strong spatial correlation for processing the received signal by an array of antennas with beam-forming techniques, are able to provide high-directional beam-forming gain and also reduce the interference from other undesired directions under high spatial correlated MIMO channel. The three techniques, MIMO, OFDM, and beam forming, when combined, can have significant improvement in performance as compared to normal nonhybrid system.
Broadband In-Home Statistics and Stochastic Modelling
Published in Lars T. Berger, Andreas Schwager, Pascal Pagani, Daniel M. Schneider, MIMO Power Line Communications, 2017
Andreas Schwager, Pascal Pagani, Daniel M. Schneider, Rehan Hashmat, Thierry Chonavel
The relation between the MIMO paths can be attributed by the spatial correlation which is an important measure of the MIMO channel. The spatial correlation affects not only the channel capacity (see Chapter 9) but also the performance of different MIMO schemes (see Chapters 8 and 9). Note that a discussion on the spatial correlation of the MIMO PLC channel can be also found in Chapter 4. The condition number of a matrix can be used as a measure of the spatial correlation. The condition number is defined as the ratio of the largest singular value to the smallest singular value: () 20*log10(λ1λ2).
MIMO Systems for Diversity and Interference Mitigation
Published in Jerry D. Gibson, Mobile Communications Handbook, 2017
The spatial correlation is in general related to the angular distribution of the rays and the antenna elements spacing. Roughly speaking, many scatterers around the receiver (transmitter) give low correlation at the receiver (transmitter) side, while if all paths at one side arrive from a small angle, the correlation on that side is large, implying an overall rank-deficient channel.
Combined Effects of Multi-User Interference and Correlated Fading on MIMO Interference-Unaware Transceiver
Published in IETE Journal of Research, 2023
Then we explore the impact of transmit correlated fading on the achievable rate of IUT by modeling as per (16) with and the (k, j) entry of specified as where is the spatial correlation factor. In Figure 3, we plot the average achievable rate per user (in bps/Hz) versus the spatial correlation factor () of transmit correlated fading for different number of transmit/receive antennas. This figure shows that the average achievable rate can increase with the spatial correlation factor. Since increasing the spatial correlation factor increases the correlations for all elements of the channel matrix, it is clear that the result obtained in Figure 3 is consistent with the analytical results in Section 4, which shows that the achievable rate of receiver i can increase (as a result of the decrease in the eigenvalues of ). In Figure 4, we plot the average achievable rate per user (in bps/Hz) of IUT versus the number of receive antennas, where we assume that there are two transmit antennas and the SNR is equal to 20 dB. Note that the one-cochannel-user case is equivalent to the interference-free case, thus it can be seen from this figure that even if there is transmit correlated fading, the achievable rate of IUT can converge to the interference-free MIMO channel capacity as the receive-antenna number increases. The reason is that the interference-free criterion is independent of transmit correlated fading. We also found from Figure 4 that increasing the spatial correlation factor can decrease the required number of receive antennas for becoming interference free and can decrease the achievable rate. The former is because increasing the spatial correlation factor can reduce the rank of the covariance matrix so that according to the interference-free criterion, the required number of receive antennas for becoming interference free can be decreased. The latter is because when the interference is free, there is no impact from the interference so that increasing the spatial correlation factor can decrease the achievable rate as expected by the analytical results in Section 4, which shows that the achievable rate of receiver i can decrease (as a result of the decrease in the eigenvalues of ).