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1

Improving Performance of MC-CDMA Systems Using UTTCM Channel Coding

Bendjillali Ridha Ilyas, Bendelhoum Mohammed Sofiane, Abderraouf Elarbi, Lahcene Mohamed

Journal of Telecommunications and Information Technology

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2024

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nr 2

58--65

EN

Over the past decade, personal communications have witnessed exponential growth, fueled by the increasing number of connected users and the diversity of transmitted data types. This expansion necessitates a boost in the transmission systems' capacity to accommodate higher user numbers and data rates, simultaneously striving to optimize cost and complexity. Consequently, future communication systems are pivoting towards multi-carrier spread spectrum techniques (MC-CDMA), capitalizing on the robustness of OFDM multi-carrier transmissions against multipath propagation and leveraging the flexibility of the code division multiple access (CDMA) technique. \\This study addresses data transmission quality-related concerns within an MC-CDMA system by implementing UTTCM error correction codes. These codes aim to enhance channel spectrum efficiency and mitigate error probability. Simulation results demonstrate that the proposed transmission scheme offers significant improvements in terms of bit error rate and signal-to-noise ratio, while maximizing the bandwidth shared among users. Additionally, the incorporation of such equalization techniques as zero forcing (ZF) and minimum mean square error (MMSE), ensures extensive compensation for the channel selectivity effect

2

Improved Two-Dimensional Double Successive Projection Algorithm for Massive MIMO Detection

Chakraborty Sourav, Sinha Nirmalendu Bika, Mitra Monojit

International Journal of Electronics and Telecommunications

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2023

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Vol. 69, No. 1

139--146

EN

In a massive multiple-input multiple-output (MIMO) system, a large number of receiving antennas at the base station can simultaneously serve multiple users. Linear detectors can achieve optimal performance but require large dimensional matrix inversion, which requires a large number of arithmetic operations. Several low complexity solutions are reported in the literature. In this work, we have presented an improved two-dimensional double successive projection (I2D-DSP) algorithm for massive MIMO detection. Simulation results show that the proposed detector performs better than the conventional 2D-DSP algorithm at a lower complexity. The performance under channel correlation also improves with the I2D-DSP scheme. We further developed a soft information generation algorithm to reduce the number of magnitude comparisons. The proposed soft symbol generation method uses real domain operation and can reduce almost 90% flops and magnitude comparisons.

3

Investigation of VBLAST Equalization Technique for Underwater Acoustic Communications

Pranitha B., Anjaneyulu L., Minh Hoa, Aslam Nauman, Kumar Sandeep V.

International Journal of Electronics and Telecommunications

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2020

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Vol. 66, No. 2

331--337

EN

Underwater Acoustic Communications (UWAC) is an emerging technology in the field of underwater communications, and it is challenging because of the signal attenuation of the sound waves. Multiple Input and Multiple- Output (MIMO) is introduced in UWAC because of its support in enhancing the data throughput even under the conditions of interference, signal fading, and multipath. The paper presents the concept and analysis of 2 × 2 MIMO UWAC systems that uses a 4 - QAM spatial modulation scheme thus minimizing the decoding complexity and overcoming the Inter Channel Interference (IChI). Bit Error Rate (BER) investigation is carried out over different link distances under acoustic Line of Sight (LOS). The utilization of Zero Forcing (ZF) and Vertical-Bell Laboratories Layered Space-Time (VBLAST) equalizers, which estimates the transmitted data proves a success of removing Inter Symbol Interference (ISI). The ISI caused due to multipath effect and scattering in UWAC can be reduced by iterative process considered in VBLAST. A study is made on how the distance between the transmitter and the receiver and the Doppler Effect has its impact on the performance of the system.

4

FPGA Implementation of Sphere Detector for Spatial Multiplexing MIMO System

Mohamed Asma, Zekry Abdel Halim, Ibrahim Reem

International Journal of Electronics and Telecommunications

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2019

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Vol. 65, No. 2

245--252

EN

Multiple Input Multiple Output (MIMO (techniques use multiple antennas at both transmitter and receiver for increasing the channel reliability and enhancing the spectral efficiency of wireless communication system.MIMO Spatial Multiplexing (SM) is a technology that can increase the channel capacity without additional spectral resources. The implementation of MIMO detection techniques become a difficult mission as the computational complexity increases with the number of transmitting antenna and constellation size. So designing detection techniques that can recover transmitted signals from Spatial Multiplexing (SM) MIMO with reduced complexity and high performance is challenging. In this survey, the general model of MIMO communication system is presented in addition to multiple MIMO Spatial Multiplexing (SM) detection techniques. These detection techniques are divided into different categories, such as linear detection, Non-linear detection and tree-search detection. Detailed discussions on the advantages and disadvantages of each detection algorithm are introduced. Hardware implementation of Sphere Decoder (SD) algorithm using VHDL/FPGA is also presented.

5

Using Least Mean p-Power Algorithm to Correct Channel Distortion in MC-CDMA Systems

Zidane M., Safi S., Sabri M., Frikel M.

Journal of Telecommunications and Information Technology

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2018

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nr 3

23--30

EN

This work focuses on adaptive Broadband Radio Access Network (BRAN) channel identiﬁcation and on downlink Multi-Carrier Code Division Multiple Access (MCCDMA) equalization. We use the normalized BRAN C channel model for 4G mobile communications, distinguishing between indoor and outdoor scenarios. On the one hand, BRAN C channel parameters are identiﬁed using the Least Mean p-Power (LMP) algorithm. On the other, we consider these coeﬃcients in the context of adaptive equalization. We provide an overview and a mathematic formulation of MC-CDMA systems. According to these fundamental concepts, the equalizer technique is investigated analytically to compensate for channel distortion in terms of the bit error rate (BER). The numerical simulation results, for various signal-to-noise ratios and diﬀerent p threshold, show that the presented algorithm is able to simulate the BRAN C channel measured with different accuracy levels. Furthermore, as far as the adaptive equalization problem is concerned, the results obtained using the zero-forcing equalizer demonstrate that the algorithm is adequate for some particular cases of threshold p.

6

Signal detection methods for MIMO systems

Nadolna D.

Poznan University of Technology Academic Journals. Electrical Engineering

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2007

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No 54

157-164

EN

Multiple-input multiple-output, wireless systems are able to realize high spectral efficiency and high performance communication links. The benefits from using multiple antennas at the transmitter and receiver are associated with some costs. The most essential difficulty for this kind of systems is the increased complexity of recovering the transmitted signal. When the capacity rises linearly, the detection complexity increases exponentially. This paper presents an overview of the signal detection methods known in theory and particularly describes the main design approaches to MIMO systems: spatial multiplexing and transmit diversity. The article shows classes of receivers, which are used in these strategies. The most important algorithms with their assumptions and computational complexity are also discussed. The introduced receivers are briefly characterized and compared.