Design Of Mobile Communication Systems Research Articles

Analyzing radiowave multiple diffraction from a low transmitter in vegetated urban areas using a spherical-wave UTD–PO approach

This article introduces a uniform theory of diffraction–physical optics (UTD–PO) formulation for analyzing radiowave multiple diffraction emanating from trees and buildings in green urban areas, considering illumination from a low transmitter and assuming spherical-wave incidence. Based on Babinet’s principle, this solution models buildings as rectangular sections and accounts for the influence of tree crowns (assuming these rise above the average rooftop height) by incorporating appropriate attenuation factors/phasors into the diffraction phenomena of buildings. The validation of the formulation is achieved through measurements made at the 39 GHz 6G mmWave frequency on a scale model of a green urban environment comprising bonsai trees and bricks. The main advantage of the proposed solution is that the calculations only include single diffractions due to recursion, circumventing the need to use higher-order diffraction terms in the diffraction coefficients, thus reducing the computation time and power. Our results may be beneficial for the design of mobile communication systems, including 6G networks, situated in green urban areas and with transmission source positioned lower than the surrounding infrastructure.

Plane-wave UTD-PO formulation for multiple-plateau diffraction analysis assuming negative incidence angles

We present a detailed methodology for investigating radiowave multiple diffraction events over rectangular barriers (here termed plateaus) when exposed to a plane wave originating from a low-lying source. Based on Babinet’s principle, our approach uses the combined uniform theory of diffraction-physical optics (UTD-PO), and is validated via 60 GHz measurements performed on a scaled replica of the setting under investigation. As an additional validation, theoretical results at 2 GHz of the corresponding spherical-wave solution converge with those of the presented plane-wave formulation with expanding distance between the source and the first obstacle. The proposed method has a crucial advantage in that it solely considers single diffractions via recursion, thus precluding the need for the diffraction coefficients to include higher order diffraction terms. The work’s findings and insights are salient for mobile communication system design in settings where the adjacent rectangular structures are higher than the transmitting antenna.

Design of Mobile Communication System for Emergency Services

<span>Telecommunication technology serves several fields in the world. One of the most significant fields is the emergency services to provide a fast connection between the case, the vehicle and emergency treatment office. This paper is a part of a long-term project to design a reliable communication system service to be used for emergency services of a specific city. The hardware devices of this system are intended to work within an mm waves frequencies. In the current research, as a starting point, an exhaustive study accomplished to pave the way to the main goal of the project. The system uses OFDM technology to improve the performance of the system. Other requirements for error correction are also included in the model such as convolutional, hamming coding and interleaving. The system development is supported by a Matlab interface software to simulate the job of an IoT real-time network covering both vehicles and the control centres.</span>

New mobile communication system design for Rayleigh environments based on compressed sensing‐source coding

A new end-to-end communication system is proposed to increase transmission speed, robustness, and security in order to meet the requirements of mobile systems that know an exponentially increasing data amount over time. The design relies on the use of compressed sensing-source coding instead of the supported speech coding standards in actual mobile communication systems. The proposed compressed sensing-source coding method allows reducing the speech coding complexity by using simple quantisation and binary encoding, saving communication system resources, and encrypting communications without additional costs. The performance of the resulting communication system is evaluated for speech communication via 10 dB Rayleigh environment in terms of perceptual evaluation of speech quality (PESQ) scores and coherence speech intelligibility index (CSII) when convolutional coding, orthogonal frequency division multiplexing, and diversity schemes are used. Results report that for a bit rate of 12.8 kbit/s the proposed scheme achieves fair speech intelligibility justified by a CSII value of 0.5, and offers good output speech quality measure, providing a PESQ of 3.33 for the same bit rate.

Cardinality improvement of Zero Cross Correlation (ZCC) code for OCDMA visible light communication system utilizing catenated-OFDM modulation scheme

In this paper, we proposed a new OCDMA-VLC system design utilizing new modulation scheme known as catenated-OFDM (orthogonal frequency division multiplexing) technique. The catenated-OFDM-OCDMA-VLC system is demonstrated by implementing Zero Cross Correlation (ZCC) code. ZCC code is the preferred code generation in OCDMA system as the effect of multiple access interference (MAI) can be cancelled out due to reduction in Phase Intensity Induced Noise (PIIN). In particular, the use of catenated-OFDM and its application in intensity modulation and direct detection fiber optic visible light communication link is theoretically investigated by taking into account all the noises contribute in the visible light spectrum. The theoretical results demonstrated that cardinality enhancement with doublefold, triplefold and fourfold increase in number of user for (Band = 2), (Band = 5) and (Band = 8) respectively compared to previous ZCC-VLC system designs. The results also indicates a good performance with high data rate up 10Gbps using proposed system which is predicted to be new considerable for upcoming OCDMA-VLC mobile communication system design.

Scattered Pilot-Based Channel Estimation for Channel Adaptive FBMC-OQAM Systems

Shaping the pulse of FilterBank MultiCarrier with Offset Quadrature Amplitude Modulation subcarrier modulation (FBMC-OQAM) systems offers a new degree of freedom for the design of mobile communication systems. In previous studies, we evaluated the gains arising from the application of Prototype Filter Functions (PFFs) and subcarrier spacing matched to the delay and Doppler spreads of doubly dispersive channels. In this paper, we investigate the impact of having imperfect channel knowledge at the receiver on the performance of Channel Adaptive Modulation (CAM) in terms of channel estimation errors and Bit Error Rate (BER). To this end, the channel estimation error for two different interference mitigation schemes proposed in the literature is derived analytically and its influence on the BER performance is analyzed for practical channel scenarios. The results show that FBMC-OQAM systems utilizing CAM and scattered pilot-based channel estimation provide a significant performance gain compared with the current one system design for a variety of channel scenarios (“one-fits-all”) approach. Additionally, we verified that the often used assumption of a flat channel in the direct neighborhood of a pilot symbol is not valid for practical scenarios.

A New Analytical Approach to Estimate Fading in Mobile Communication System Design

This paperprovides a novel analytical platform for evaluating theessential second order statistical boundaries for fading in mobile communication for average fade duration (AFD) and levelcrossing rate (LCR) of Rayleigh, Rician and Nakagami fading channels. We derive new expressions for average LCR and AFD. We then model and computationally simulate the proposed method for Rayleigh, Rician and Nakagami channels and separately calculate the LCR and AFD for each channel by this approach. Simulated results obtained for all three channels show that the values of LCR and AFD calculated by using the proposed approach are much closer to actual simulated values than what conventional theoretical formulas deliver.

Experimental Investigation of the Relationship between Operating Temperature and Power Handling Capability of High-Temperature Superconducting Dual-Band Bandpass Filter

Abstract This paper experimentally investigates the relationship between the operating temperature and the power handling capability (PHC) of a coplanar waveguide (CPW) high-temperature superconducting (HTS) dual-band bandpass filter (DBPF) using a YBCO thin film deposited on a MgO substrate. The PHC is evaluated based on the intermodulation distortion of the HTS-DBPF. Experimental results show that the PHC does not change depending on how signals are input to the passbands of the HTS-DBPF at 50 K, 60 K, and 70 K, which leads to a straightforward design of mobile communication systems.

Curtailed-Gaussian and Cosine Functions for Multihop Doppler Spectrum Modeling

Wireless channels are characterized among others by their Doppler spectrum. In the cooperative diversity, one of diversity branch may consist of several mobile relays forming multihop link which each hop introduced Doppler shift. With employing amplify-and-forward (AF) relays, the Doppler shift keeps accumulating to the end of the link. Doppler shift value affects the time varying channel rate, which is a challenge in broadband mobile communication system. Hence, the Doppler parameter is very important and must be considered in broadband mobile communication system design and analysis. Unfortunately, it is hard to derive the expressions of this Doppler spectrum in a closed form since a special function under integration such as complete elliptic integral exists. To solve this problem, curve-fitting method base on least-square is used. In this process, curtailed-Gaussian and cosine functions are proposed as an approximation function. Then, from Kullback-Leiber divergence test, it is showed that both proposed functions, i.e., curtailed-Gaussian and cosine functions have a good approximation as Doppler spectrum modeling of Multihop mobile channel with all gain relays assumed as 1 and all mobile terminals are assumed move with almost same velocity.

기지국 위치 문제를 위한 목적함수의 최적해 및 근사해

The problem of selecting base station location in the design of mobile communication system has been basically regarded as a problem of assigning maximum users in the cell to the minimum base stations while maintaining minimum SIR. and it is NP hard. The objective function of warehouse location problem, which has been used by many researchers, is not proper function in the base station location problem in CDMA mobile communication, The optimal and approximate solutions have been presented by using proposed object function and algorithms of exact solution, and the simulation results have been assessed and analyzed. The optimal and approximate solutions are found by using mixed integer programming instead of meta-heuristic search methods.

Research on Asymmetric Characteristics of Mobile Communications System Based on Electromagnetic Radiation

It's well known that data tra-c brings asymmetry which is called Service Asym- metry (SA) to mobile communications system. This paper discusses asymmetry between uplink and downlink in mobile communications system in a new aspect | in view of the efiects of elec- tromagnetic radiation to human body, which is termed as Electromagnetic Asymmetry (EA). It's stated that both EA and SA should be taken into account, but EA has higher priority to SA. By calculating, it's concluded that under the restriction of electromagnetic radiation, the downlink data rate should be much higher than that of uplink. It is demonstrated that to adapt to EA and SA, the equivalent bandwidth of uplink should be narrower than that of downlink in view of duplex techniques including FDD and TDD. In the future, most mobile communications services will be asymmetric, such as high multime- dia (1,3). The downlink of service requirement is much greater than the uplink both in transmission total amount and transmission rate. So this asymmetric transmission characteristic is caused by tra-c demand (2{4). We call it as Service Asymmetry (SA) between uplink and downlink. Nowadays, only SA is considered as the efiect of asymmetric characteristic. In this paper, we also consider the asymmetric characteristic of uplink and downlink caused by electromagnetic radiation, which is termed as Electromagnetic Asymmetry (EA) between uplink and downlink. The in∞uence on surrounding environment caused by electromagnetic radiation is always a controversial problem. With the large-scale application of mobile communications, the total amount of electromagnetic radiation will increase and people will have to re-evaluate the social efiect of mobile communications (5). The in∞uence of electromagnetic radiation will be one of the most important elements which should be considered in research and design of mobile communications system. This paper analyzes the asymmetric characteristics of mobile communications system in∞uenced by electromagnetic radiation. The structure of this paper is as follows: Section 2 analyses the characteristics of asymmetric transmission caused by electromagnetic radiation in∞uence, Section 3 studies the methods to adapt to EA in view of duplex technique, and Section 4 is the conclusion. 2. THE ASYMMETRIC TRANSMISSION CHARACTERISTICS OF MOBILE COMMUNICATIONS CAUSED BY ELECTROMAGNETIC RADIATION It is notable that the mobile terminal is very close to human body, which is a small transceiver. The distance from mobile terminal to human body ranges from several centimeters to dozens of centimeters. In contrast to that, the distance from base station to human body is much longer, which ranges from dozens of meters to several kilometers. So the electromagnetic radiation impact on human body caused by mobile terminal is much more intense than that caused by base station. Then, we will respectively calculate the radiation power to human body caused by base station and mobile terminal. 1. Radiation power of base station absorbed by human body As there is a long distance from base station to human body, under the presupposition of ideal LOS propagation environment, we can use the Free Space Propagation Model. The power received by human body is Pr = AeGtPt 4…d 2 (1)