Performance of a precoded high speed wireless communication system over time-varying indoor channels

The paper emphasizes on the analysis on wideband channel model for high speed wireless communication systems. The research problem in this study are based on the following concepts such as (i) Firstly, it is necessary to change to the appropriate physical devices that can support 5G system, (ii) It is required to design a channel that will adapt to the medium that will be convenient for the changed physical devices, and (iii) Mobile terminals that currently use 4G cannot be used in 5G system. The objectives in this study are - to analyze the existing channel model for mobile communication, to analyze the mathematical and dynamical model for wireless propagation channel, to implement the wireless propagation channel with specific purposes, to implement the optimized channel model performance, and to evaluate the performance of the developed channel design. The numerical analyses in this study are conducted by using MATLAB language. The research direction in this study are based on the channel system functions, and tapped delay-line models. The simulation results are confirmed that the 12 taps in this study for the high speed wireless communication system design.

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.

A refined phase estimation based parallel carrier recovery algorithm for high speed wireless communication systems is proposed in this paper. This parallel algorithm is based on a serial DPLL (digital phase locked loop) carrier recovery feedback architecture and a novel refined phase estimation module. To archive high speed communication, parallelization of serial DPLL carrier recovery algorithm is presented; to guarantee high accuracy, a refined phase estimation design is proposed. A 32 parallel baseband simulation model of 16QAM modulation is performed on MATLAB platform to validate the proposed algorithm. Simulation results demonstrate that the performance loss of EVM (Error Vector Magnitude) introduced by the proposed algorithm is less than 0.3%, which is only half of the traditional coarse compensation algorithm.

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.

We present linear precoding methods for downlink transmission in multi-user multiple-input multiple-output (MIMO) systems where channel state information (CSI) can be obtained through training. In this paper, channel training overhead and estimation error are rigorously accounted for while determining the net system throughput. First, we consider the case with training on the reverse link only. We study a precoding method which is a combination of two schemes: selection of users with largest estimated gains and zero-forcing to selected users. Next, we consider the case with training on both reverse and forward links. We obtain a lower bound on the weighted-sum capacity, and propose an algorithm to determine an efficient precoding matrix. This precoding method effectively utilizes the training on the reverse and forward links in improving net throughput.

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.

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.

We considered call admission control (CAC) algorithms both for the reverse and forward link with multiple types of services requiring different SIRs (signal to interference ratio) and transmission rates. In the forward link, a call is admitted if the requested power is available at the base station, whereas in reverse link, a call is admitted if the interference level is below a certain revel that guarantees the communication quality. First, the optimal power ratio that characterizes the effect of different service types is considered. Then a simple CAC algorithm is proposed and evaluated through simulation. With these CAC algorithm, we compare the capacity of forward link and reverse link for commonly used SIR equations.

In this paper the performance of an indoor wireless communication system is investigated. Adaptive decision feedback equalisers (DFE) are used to mitigate the intersymbol interference (ISI) caused by multipath propagation in the indoor radio channel. The system can be described as follows. It is a 16 quadrature amplitude modulation (16-QAM) system with raised cosine matched filtering with a roll-off factor of 0.50. A realistic channel model is used in the simulations by interpreting complex measured impulse responses of indoor radio channels. The measurements used were done in different types of rooms, and for line-of-sight (LOS) and obstructed (OBS) situations at the frequency of 2.4 GHz. After the signals have gone through the multipath channel additive white Gaussian noise (AWGN) was added. Symbol error rate (SER) performance simulations were done for different signal-to-noise ratios (SNR) and different data rates. On the average the SER performance was a few orders of magnitude (2-4) better than was the case without adaptive equalisation, depending on the SNR.

This paper outlines the current state of Network MIMO as a viable technique for increasing the performance of wireless communication systems by cancelling the intercell interference in the near future. It also presents the results of a simulation environment designed to compare the BER performance capabilities of a wireless multiuser OFDM systems with and without the use of Network MIMO. Simulations confirm that Network MIMO techniques can result in significant reductions in interference. “Network MIMO” is a family of techniques where each user in a wireless system is served through all the access points within its range of influence. Taking prior information theoretic analyses of MIMO to the next level, this report quantify the spectral efficiency gains obtainable under realistic propagation and operational conditions. The results confirm that Network MIMO stands to provide a multiple fold increase in spectral efficiency by cancelling intercell interference and reducing Bit-Error-Rate under such conditions.

We investigated the performance of wireless optical communication systems with polarization shift keying modulation when the atmospheric turbulence is anisotropic. Based on the unified theory of polarization and coherence, the characteristic of polarization crosstalk on propagation was shown. Moreover, we explored the effects of propagation distances and turbulent parameters on the signal-to-noise ratio loss of communication system. The results illustrated that polarization crosstalk of horizontal direction on the vertical direction is the main factor affecting communication performance. And it is more conducive to transmit information when the turbulence is anisotropic and the difference between two anisotropic factors is small.

The outage and handoff probabilities for the reverse link of wireless communication systems have been extensively studied (A.J. Viterbi et al., Oct. 1994) (Yu-Wen Chang and E. Geraniotis, 1996). But there are no similar studies on the forward link. We establish an analytical model to study the effects of handoff threshold and path loss margin on the outage. The effects of channel propagation statistics and signal correlation are also addressed. The simulation results show how the soft handoff region and outage probability can be adjusted by varying the path loss margin and handoff threshold. Furthermore, the path loss margin of the forward link is compared to that of the reverse link.

Reconfigurable intelligent surface (RIS) has recently been regarded as a potential technique to enhance the performance of wireless communication systems by creating additional communication links. However, it is almost impossible to get the perfect channel state information (CSI) from the base station (BS) to the Internet of Things Devices (IoTDs) and the RIS-related channels. Furthermore, residual transceiver hardware impairments inevitably affect the performance of wireless communication systems. Hence, we study the robust design for an RIS-aided wireless communication system based on the imperfect CSI and hardware impairments. Minimizing the power consumption of BS is formulated by ensuring the minimum signal-to-interference-plus-noise ratio (SINR) demands of the IoTDs and the unit-modulus constraints of the RIS. Specifically, after approximating the nonconvex constraints by using the S-procedure and the successive convex approximation (SCA) methods, we adopt the block coordinate descent (BCD) technique to iteratively optimize one set of variables while keeping the other variables fixed in various channel uncertainty scenarios. Simulation results demonstrate that the influence of transceiver hardware impairments can be effectively decreased by deploying RIS even with channel uncertainty, which is more advantageous than increasing the number of BS’s antennas.

Measuring the physical layer performance of wireless radio communication systems is one important step in clearly understanding their behavior in real-world, that is, non-simulation, environments. Unfortunately, measurements in wireless communications are extremely expensive and time-consuming. In fact, they require researchers to deal with nonartificial, realizable, real-world problems. They also require these researchers to have experience in computer engineering, telecommunication engineering, electrical engineering and often even mechanical engineering. Finally, they require teamwork to set up complete systems instead of dealing with single, isolated, numerical environments.

The authors present a novel cell structure that combines the qualities of code division multiple access (CDMA) and time division multiple access (TDMA) to reduce cochannel interferences. The cell consists of a centrally located base station with eight surrounding corner antennas. The mobiles and antennas operate in a TDMA mode and the communication channels employ spread spectrum direct sequence modulation. TDMA combined with the spatial separation of the cell antennas reduces the carrier-to-interference ratio and thereby increases the cell capacity. The capability and cochannel interference for both forward and reverse link of the proposed system are computed and compared with that of the traditional CDMA cellular system. The results show that the capacity of the proposed system in the forward link is increased by an average factor of three over the traditional CDMA cellular system. For the reverse link the capacities of the systems are comparable. >