Interference cancellation and BER improvement in a wireless network using Network MIMO

Vehicle-to-vehicle and vehicle-to-infrastructure wireless communications are currently under development to improve traffic efficiency and safety. The time-critical nature of road safety applications imposes the need to accurately dimension the operation and performance of wireless vehicular communication systems. Given that radio propagation modeling has been shown to importantly affect the performance of traditional mobile and wireless communication systems, this work investigates its impact on the dimensioning of traffic safety wireless vehicular communications by separately analyzing the contributions of pathloss, shadowing and fast fading.

We employ a simulation environment to investigate the influence of hardware parameters on the performance of wireless communication systems at THz frequencies under realistic propagation constraints. The achievable data rates and the required channel bandwidths are estimated for a range of hardware and system parameters in an indoor scenario.

Recently, the growing demands for ultra-high speed applications require more advanced and optimal data transmission techniques. Wireless autoencoders have gained significant attention since they provide global optimization of the transceiver structure. This article explores the application of autoencoders to enhance the performance of wireless communication systems. It provides the performance evaluation of the systems using single-carrier and OFDM-based autoencoders under the conditions of AWGN and fading channels. Then, in terms of the BLER metric, the wireless systems with autoencoders are compared with conventional systems using LDPC coding and quadrature amplitude modulation for various configurations. Simulation results indicate that for high-modulation orders (QAM-64 or QAM-256), communication systems employing autoencoders provide superior performance compared to systems using LDPC channel encoding in regions with a low signal-to-noise (SNR) ratio. Specifically, a gain of 1–2 dB in signal power is obtained for single-carrier autoencoders and 0.3–2 dB is obtained for OFDM-based autoencoders. Therefore, wireless communication systems utilizing autoencoders can be considered as a promising candidate for future wireless communication systems.

To meet the goal of tenfold increase in spectral efficiency, interference cancellation and multiuser detection are expected to be important tasks of fifth-generation (5G) radio access systems. Both tasks can be realized by joint detection algorithms. However, joint detection algorithms such as maximum likelihood (ML) detection have a high computational complexity. Previous works have shown that joint detectors based on Markov chain Monte Carlo (MCMC) methods can achieve similar results compared to ML detection with a large reduction in the computational complexity for systems with a large number of streams or users. The purpose of this work is to present a MIMO joint detector based on MCMC methods and evaluate it within the constraints of LTE Advanced (LTE-A), namely, using at most 8 transmit antennas and 64-QAM modulation. The evaluation is done separately from the channel decoder. Moreover, the complexity of the presented algorithm is compared to the one of an ML detector. The results show that the proposed MIMO detector offers a similar detection error rate compared to an ML detector. Furthermore, it was observed that the complexity reduction is significant for systems with more than six transmit antennas.

Under a radio frequency man-made noise environment, it is well-known that the performance of digital radio communication system is much degraded. Although man-made noise emitted from a noise source is propagated through a multipath radio channel, the direct path component appears as the highest level component which dominates the performance of a digital radio communication system. We propose a method to mitigate the effect of man-made noise on the performance of a digital radio communication system by a sector antenna at the receiver and transmitter. The numerical results conclude that the error performance can be much improved by using the proposed system.

In this paper, we propose self-interference (SI) cancellation in cooperative multiple-input multiple-output (Co-MIMO) for full-duplex (FD) wireless communication systems. This proposal solves SI by applying the block diagonalization used in multi-user MIMO. Therefore, there is no need for a radio frequency (RF) canceller, which has a large hardware (HW) size and is difficult to extend to MIMO. Furthermore, we can achieve higher throughput by applying Co-MIMO, in which multiple access points (APs) work together to communicate. The proposed method's implementation uses field-programmable gate array (FPGA) and software-defined radio (SDR). In the experiment, a total of 33 [dB] SI can cancel with two cooperative APs and two antennas per AP in the IEEE 802.11 system.

This paper proposes a transmission diversity (TD) technique combined with orthogonal frequency division multiplex (OFDM) modulation to enhance packet-error-rate (PER) performance in microcell broadband wireless communication systems. The proposed TD technique selects the antenna with the anticipated better-channel conditions in a subchannel-by-subchannel manner at the access point (AP) based on the quality-measurement results of signals sent by the mobile terminal (MT). In the subsequent transmission timing from the AP to the MT, each antenna at the AP station transmits OFDM-modulated signals that only possess the selected subchannel components. On the MT side, the space-combined whole subchannel OFDM signal is received through the single antenna.

The advance in wireless sensor networking technology is increasing the number of control systems that use these networks to transmit the relevant variable to be measured and controlled, despite of the more intense distortions caused by wireless channels. The performance of wireless communications systems is mainly limited by fading produced by multipath propagation. In order to minimize the fading effects, channel coding and diversity techniques are often used in wireless systems. Among the known coding techniques in the literature, the wavelet coding presents an interesting alternative to overcome the multipath fading, since it gets performance gain by transmitting in time diversity without compromising spectral efficiency. This paper investigates the use of wavelet coding in a system that operates over a wireless channel to control the rotation frequency of the direct current motor. Aspects such as packet error probability performance, hardware complexity and processing delays due to wavelet coding are analyzed, as well as its beneficial effects on the control system. In the proposed system, the wavelet coding was embedded in PIC microcontroller and a radio transceiver XBee is used to establish a wireless link. The obtained results demonstrate a reduction of fading effects on the control signal, as well as, a low cost for hardware implementation and a small impact on system processing time.

Multiuser MIMO (MU-MIMO) in which the base station transmits multiple streams to multiple users, has received significant importance as a way of achieving spectral efficiency (SE) and energy efficiency (EE). However, these two important design criteria conflict with each other and a careful study of their trade-off is mandatory for designing future wireless communication systems. This paper investigates the trade-off between EE and SE in downlink MU-MIMO system which is adopted by 3GPP Long Term Evolutions (LTE). The EE is measured as, “throughput (bits) per Joule” while both RF transmit power and circuit power consumptions are considered. In this paper, given the SE requirement, a constrained optimization problem where a constraint redefined with cubic inequality is formulated to maximize EE. Then, a novel resource allocation algorithm is proposed to achieve maximum EE. Simulation results demonstrate the effectiveness of the proposed scheme and illustrate the fundamental trade-offs between energy efficient and spectral efficient transmission.

Although tremendous research has conducted on high speed communications but still number of research works which are reported in literature are fails to meet the real time requirement. The main drawbacks in the conventional communication techniques are low spectral efficiency, lack of high rate, interferences, etc. The OFDM communication model overcomes the drawbacks of conventional communicational model and offers the high data rate, and high spectral efficiency. Although OFDM has many advantages over FDM but it suffers from inter carrier interference and inter symbol interference when multiple carriers are used and due to this interferences loss of Orthogonality happens, in order to overcome these interferences usage of cyclic prefix has become mandatory. But usage of cyclic prefix shows huge negative impact on bandwidth efficiency as the cyclic prefix approach consumes nearly 20% of bandwidth and BER performance too affected by CP. In this paper a novel wavelet based OFDM model is presented which is mainly intended to provide good Orthogonality and better spectral efficiency using various modulation techniques, the unique thing in the usage of wavelet based OFDM is it does not need the cyclic prefix, CP decreases bandwidth efficiency. But wavelet increases bandwidth and when bandwidth increases simultaneously spectral efficiency increases. Finally the usage of the wavelet based OFDM shows improved BER over conventional FDM communication model. The simulation results indicates the usage of wavelet based OFDM in place of Fourier based OFDM in wireless system and finally the comparison between wavelet based OFDM and DFT based OFDM. In this paper for simulation purpose Additive white Gaussian noise channel (indoor channel) and Stanford University Interim (SUI) channels are used. Here Sanford University channel works like outdoor channel. In every channel and for every modulation scheme wavelet gives improved Bit Error Rate.

Objectives: The objective of using cross layer approach in Adaptive Modulation and Coding (AMC) based wireless systems is to enhance the spectral efficiency and reliability of transmission n time varying MIMO channel. Methods: A cross layered design using k-NN based AMC with Improved Low-Density Parity Check Accumulate codes (ILDPCA) that opt for nonuniform division of check nodes at the physical layer and Incremental Redundancy Hybrid Retransmission Request (IRHARQ) at the link layer is implemented. The encoded symbols are routed consecutively over MIMO fading channels. The MIMO channel is predicted at the receiver and is forwarded to the AMC controller. IR-HARQ regulates packet retransmission with new codeword on failure. Findings: The performance of the cross layer design is assessed in terms of BER, packet loss and spectral efficiency. The proposed cross layer with ILDPCA coders improves the spectral efficiency by 45% compared to the conventional systems but still maintaining acceptable PLR. Application: Therefore the proposed adaptive system can be adopted for reliable adaptive transmission over MIMO network and is suitable for multimedia applications. Keywords: Cross Layer, Multiple Input Multiple Output, Reliability, Wireless System Design

10 - Improving energy efficiency in next-generation IoT networks with beam adjustment technique

The propagation of electromagnetic (EM) waves plays a fundamental role in the performance of high-speed wireless communication systems. As wireless technologies evolve, the demand for faster data rates and more reliable connections is driving the need for a deeper understanding of EM wave behavior. This article explores the principles of EM wave propagation in high-speed wireless systems, including the factors that affect signal transmission, such as attenuation, diffraction, reflection, and scattering. We examine the challenges posed by different environments, such as urban, rural, and indoor settings, and discuss the technologies used to overcome these challenges in next-generation wireless systems, including 5G and beyond.

Research into cutting-edge systems that can satisfy the rising needs for greater data rate and increased reliability is becoming more and more necessary as wireless communication technologies continue to evolve. To enhance the spectral and energy efficiencies, this study examine the performance of massive multiple input multiple output (mMIMO) communication systems using wavelet-order orthogonal frequency division multiplexing (W-OFDM). Also, a communication system was created based on W-OFDM Massive MIMO using MATLAB to model its operation. The simulated system's various stages of operation was examined through detailed analysis and its performance was compare with prior studies and practical networks on OFDM. Key performance metrics, specifically the data throughput, was evaluated to assess the effectiveness and viability of the system. The simulation results indicates that W-OFDM can achieve up to 35% reduction in peak-to-average-power-ratio (PAPR) compared to the traditional OFDM, with a 20% improvement in BER performance under Rayleigh fading conditions. Also, the spectral efficiency of W-OFDM mMIMO outperforms convectional OFDM by 15%, making it a viable technology for future communication networks requiring high data rates and reliability. This implies that, the analytical evaluation confirms that W-OFDM mMIMO provides substantial benefits for improving energy and spectral efficiencies in wireless communication systems, addressing the challenges of increased user demands for high spectrum. This study contributes to the understanding of MIMO systems' performance optimization, highlighting the importance of antenna configuration and cell distance. Comprehensive analysis of spectral efficiency and energy efficiency trade-offs in MIMO systems and identification of optimal antenna configuration for maximum energy efficiency, addressing some of the challenges of future wireless communication systems.

Wireless communication systems are of paramount importance in the telecommunication infrastructure and have been playing a leading role in the development of nations. However, the system is characterized by multipath propagation effects that degrade the performance of the system. Amplify Quantize and Forward (AQF) cooperative relaying technique used to address the problem is characterized by poor performance due to signal amplification and obstruction along the propagating channel between the relay and destination. Hence, in this paper, the Enhancement of AQF (E-AQF) cooperative relaying protocol is carried out to improve the performance of the Conventional AQF (C-AQF) technique in a wireless communication system. The transmitted signal from the sourceis received at the relay node and the received signal is made to pass through spectral subtraction. The resultant signal is amplified using relay gain. The amplified signal at the relay node is quantized using uniform quantization before being forwarded to the destination during second hop transmission using angular beamforming. The multiple copies of the received signal at a varying path (L = 2, 4) are combined at the destination using Equal Gain Combiner (EGC). Mathematical expressions of Bit Error Rate (BER) and Throughput (TP) are derived using PDF. The performance of the proposed technique is evaluated using BER and TP by comparing it with the C-AQF cooperative relay technique. The proposed E-AQF gave better performance with reduced BER and increased TP than the C-AQF. The proposed E-AQF can be deployed to improve the performance of wireless communication systems.