Faisal Al-kamali

Frequency Domain Interference Cancellation for Single Carrier Cyclic Prefix CDMA System

In this paper, we propose a low complexity receiver structure for Single-input Multiple-output (SIMO) downlink cyclic prefixCDMA (CP-CDMA) systems. It employs an interference cancellation scheme to suppress the interference caused by the multipath fading channel. Also, the proposed scheme is developed for Multiple-input Multiple-output (MIMO) CP-CDMA system. All filters in the proposed receiver are implemented in the frequency domain. The performance of the proposed receiver is studied and compared. Our results show a large performance improvement when using such an interference cancellation scheme relative to the rake receiver, and frequency domain Equalization (FDE).

Joint Low-Complexity Equalization and Carrier Frequency Offsets Compensation Scheme for MIMO SC-FDMA Systems

Due to their noise amplification, conventional Zero-Forcing (ZF) equalizers are not suited for interference-limited environments such as the Single-Carrier Frequency Division Multiple Access (SC-FDMA) in the presence of Carrier-Frequency Offsets (CFOs) . Moreover, they suffer increasing complexity with the number of subcarriers and in particular with Multiple-Input Multiple-Output (MIMO) systems. In this letter, we propose a Joint Low-Complexity Regularized ZF (JLRZF) equalizer for MIMO SC-FDMA systems to cope with these problems. The main objective of this equalizer is to avoid the direct matrix inversion by performing it in two steps to reduce the complexity. We add a regularization term in the second step to avoid the noise amplification. From the obtained simulation results, the proposed scheme is able to enhance the system performance with lower complexity and sufficient robustness to estimation errors.

Uplink single-carrier frequency division multiple access system with joint equalisation and carrier frequency offsets compensation

Similar to the orthogonal frequency division multiple access (OFDMA) system, the single-carrier frequency division multiple access (SC-FDMA) system also suffers from frequency mismatches between the transmitter and the receiver. As a result, in this system, the carrier frequency offsets (CFOs) disrupt the orthogonality between subcarriers and give rise to inter-carrier interference (ICI) and multiple access interference (MAI) among users. The authors present a new minimum mean square error (MMSE) equaliser, which jointly performs equalisation and carrier frequency offsets (CFOs) compensation. The mathematical expression of this equaliser has been derived taking into account the MAI and the channel noise. A low complexity implementation of the proposed equalisation scheme using a banded matrix approximation is presented here. From the obtained simulation results, the proposed equalisation scheme is able to enhance the performance of the SC-FDMA system, even in the presence of estimation errors.

Performance enhancement of SC-FDMA systems using a companding technique

In this paper, a companding technique is proposed to effectively reduce the peak-to-average power ratio (PAPR) in single-carrier frequency division multiple access (SC-FDMA) systems. By companding the samples with large amplitudes, while enhancing those with small amplitudes, a significant reduction in the PAPR can be achieved. The performance of the proposed SC-FDMA with companding system is studied and compared with that of the standard SC-FDMA system. Simulation results show that the SC-FDMA with companding system has a lower PAPR when compared with the conventional SC-FDMA system, while the complexity of the system slightly increases. Results also reveal that the companding coefficient must be chosen carefully in order to limit the PAPR without introducing degradations into the bit error rate performance.

A new single carrier FDMA system based on the discrete cosine transform

In this paper, a new single carrier frequency division multiple access (SC-FDMA) system based on the discrete cosine transform (DCT) for uplink wireless transmissions, is introduced. The time domain expressions of the DCT SC-FDMA signals are derived. The peak to average power ratio (PAPR) of the DCT SC-FDMA signals is compared with that of the discrete Fourier transform (DFT) SC-FDMA and orthogonal frequency division multiple access (OFDMA) signals. Simulation results show that the proposed DCT SC-FDMA system provides a better bit error rate (BER) performance than the DFT SC-FDMA and the OFDMA systems. In addition, it is found that the PAPR of the DCT SC-FDMA signals is lower than that of OFDMA signals.

SC-FDMA for Mobile Communications

SC-FDMA for Mobile Communications examines Single-Carrier Frequency Division Multiple Access (SC-FDMA). Explaining this rapidly evolving system for mobile communications, it describes its advantages and limitations and outlines possible solutions for addressing its current limitations.The book explores the emerging trend of cooperative communication with SC-FDMA and how it can improve the physical layer security. It considers the design of distributed coding schemes and protocols for wireless relay networks where users cooperate to send their data to the destination.Supplying you with the required foundation in cooperative communication and cooperative diversity, it presents an improved Discrete Cosine Transform (DCT)-based SC-FDMA system. It introduces a distributed spacetime coding scheme and evaluates its performance and studies distributed SFC for broadband relay channels. Presents relay selection schemes for improving the physical layer Introduces a new transceiver scheme for the SC-FDMA system Describes spacetime/frequency coding schemes for SC-FDMA Includes MATLAB codes for all simulation experiments The book investigates Carrier Frequency Offsets (CFO) for the Single-Input Single-Output (SISO) SC-FDMA system, and Multiple-Input Multiple-Output (MIMO) SC-FDMA system simulation software. Covering the design of cooperative diversity schemes for the SC-FDMA system in the uplink direction, it also introduces and studies a new transceiver scheme for the SC-FDMA system.

Equalization and Carrier Frequency Offsets Compensation for the SC-FDMA System

Recently, the Single-Carrier Frequency Division Multiple Access (SC-FDMA) system has attracted the attention as an efficient alternative to the Orthogonal Division Multiple Access (OFDMA) system in the uplink communications. In this system, the Carrier Frequency Offsets (CFOs) disrupt the orthogonality between subcarriers, and give rise to Inter-Carrier Interference (ICI), and Multiple Access Interference (MAI) among users. In this paper, the impact of the CFOs on the performance of the Discrete Fourier Transform SC-FDMA (DFT-SC-FDMA) and the Discrete Cosine Transform SC-FDMA (DCT-SC-FDMA) systems is investigated. Based on the Minimum Mean Square Error (MMSE) criterion, a new low-complexity joint equalization and CFOs compensation scheme is proposed. It is refered to as the MMSE scheme. The MMSE weights of the proposed scheme are derived taking into account the MAI and the noise. Furthermore, a hybrid scheme comprising the proposed MMSE scheme and a Parallel Interference Cancellation (PIC) stage is also suggested and investigated to further enhance the performance of interleaved subcarriers mapping systems. From the obtained simulation results, it is clear that CFOs disrupt the orthogonality between the subcarriers in SC-FDMA systems and degrade the Bit Error Rate (BER) performance. The proposed compensation schemes are able to enhance the system performance, even in the presence of the estimation errors.

Impact of the power amplifier on the performance of the single carrier frequency division multiple access system

Single-carrier frequency division multiple access (SC-FDMA) is a promising alternative to orthogonal frequency division multiple access (OFDMA) for uplink wireless communications in frequency-selective fading environments. In this paper, we investigate the impact of the power amplifier (PA) on the performance of the SC-FDMA system. The suitable saturation level thresholds of the PA that can be utilized in the SC-FDMA system are studied and determined through simulations for different modulation formats. Simulation results show that the saturation level of the PA has a significant effect on the bit error rate (BER) performance of the SC-FDMA system, especially with high order modulation formats.

Carrier frequency offsets problem in DCT-SC-FDMA system: investigation and compensation

Single-carrier frequency division multiple access (SC-FDMA) is one well-known scheme, which has recently become a preferred choice for uplink channels. In this system, the carrier frequency offsets (CFOs) disrupt the orthogonality between subcarriers and give rise to inter-carrier interference (ICI), and multiple access interference (MAI) among users. In this paper, firstly, the impact of the CFOs on the performance of the discrete cosine transform (DCT) SC-FDMA (DCT SC-FDMA) system is investigated. Then, a new low-complexity joint equalization and CFOs compensation scheme is proposed to cancel the interference in frequency domain. It is called minimum mean square error (MMSE) equalizer. A hybrid scheme comprising the proposed MMSE scheme and a parallel interference cancellation (PIC) (MMSE+PIC) is also suggested and investigated to further enhance the performance of the interleaved DCT-SC-FDMA. From the obtained simulation results, it is found that CFOs disrupt the orthogonality between the subcarriers in DCT-SC-FDMA systems and degrade the bit error rate (BER) performance. The proposed compensation schemes are found to be able to enhance the system performance, even in the presence of the estimation errors.

Regularized MIMO Equalization for SC-FDMA Systems

In this paper, we propose an efficient frequency domain equalization scheme for Multiple Input Multiple Output (MIMO) Single-Carrier Frequency-Division Multiple Access (SC-FDMA) systems. The proposed scheme avoids the complexity problem associated with the conventional MIMO Zero-Forcing (ZF) equalizer as well as the noise enhancement problem. The matrix inversion process associated with the proposed equalization scheme is performed in two steps to reduce complexity. A regularization term is added in the second step of the matrix inversion to avoid the noise enhancement. Simulation experiments on uplink MIMO SC-FDMA systems show that the proposed equalization scheme provides better performance than that of the ZF equalizer and its complexity is far less than that of the ZF equalizer.