Performance of symmetric and asymmetric links in wireless networks

<p>Wireless networks are designed to provide the enabling infrastructure for emerging technological advancements. The main characteristics of wireless networks are: Mobility, power constraints, high packet loss, and lower bandwidth. Nodes’ mobility is a crucial consideration for wireless networks, as nodes are moving all the time, and this may result in loss of connectivity in the network. The goal of this work is to explore the effect of replacing the generally held assumption of symmetric radii for wireless networks with asymmetric radii. This replacement may have a direct impact on the connectivity, throughput, and collision avoidance mechanism of mobile networks. The proposed replacement may also impact other mobile protocol’s functionality. In this work, we are mainly concerned with building and maintaining fully connected wireless network with the asymmetric assumption. For this extent, we propose to study the effect of the asymmetric links assumption on the network performance using extensive simulation experiments. Extensive simulation experiments were performed to measure the impact of these parameters. Finally, a resource allocation scheme for wireless networks is proposed for the dual rate scenario. The performance of the proposed framework is evaluated using simulation.</p>

A comparative assessment of GSM and UMTS Networks

It is common knowledge that the transition of mobile networks from one generation to another is basically for the improvement in the network’s Quality of Service (QoS). Bearing this in mind, we will assumme that the Universal Mobile Telecommunication System (UMTS) will outperform the Global System for Mobile Communication (GSM), hence, the motivation to conduct this study in Calabar, Nigeria, for four mobile networks; MTN, Airtel, Globacom and 9mobile. With the aid of a TEMS investigation software installed in a laptop, a measurement campaign was carried out and log files collected, with focus on Call Setup Success Rate (CSSR), Dropped Call Rate (DCR), Handover Success Rate (HOSR), Call Setup Time (CST), network coverage and network quality. The collected data was analyzed with the aid of a TEMS discovery software. The analyzed data for each Key Performance Indicator (KPI) was compared with the minimum benchmark of the telecommunications regulatory body, the Nigerian Communication Commission (NCC). Result reveal that there was no outright improvement in the QoS and there was fluctuation in the QoS provided by the network operators. We therefore conclude that the network operators, either did not make accurate planning before installing their base stations or do not optimize their networks frequently and this led to poor QoS in most cases.

Design and Evaluation of Remote Driving Architecture on 4G and 5G Mobile Networks

Despite the progress in the development of automated vehicles in the last decade, reaching the level of reliability required at large-scale deployment at an economical price and combined with safety requirements is still a long road ahead. In certain use cases, such as automated shuttles and taxis, where there is no longer even a steering wheel and pedals required, remote driving could be implemented to bridge this gap; a remote operator can take control of the vehicle in situations where it is too difficult for an automated system to determine the next actions. In logistics, it could even be implemented to solve already more pressing issues such as shortage of truck drivers, by providing more flexible working conditions and less standstill time of the truck. An important aspect of remote driving is the connection between the remote station and the vehicle. With the current roll-out of 5G mobile technology in many countries throughout the world, the implementation of remote driving comes closer to large-scale deployment. 5G could be a potential game-changer in the deployment of this technology. In this work, we examine the remote driving application and network-level performance of remote driving on a recently deployed sub-6-GHz commercial 5G stand-alone (SA) mobile network. It evaluates the influence of the 5G architecture, such as mobile edge computing (MEC) integration, local breakout, and latency on the application performance of remote driving. We describe the design, development (based on Hardware-in-the-Loop simulations), and performance evaluation of a remote driving solution, tested on both 5G and 4G mobile SA networks using two different vehicles and two different remote stations. Two test cases have been defined to evaluate the application and network performance and are evaluated based on position accuracy, relative reaction times, and distance perception. Results show the performance of the network to be sufficient for remote driving applications at relatively low speeds (&lt;40 km/h). Network latencies compared with 4G have dropped to half. A strong correlation between latency and remote driving performance is not clearly seen and requires further evaluation taking into account the influence of the user interface.

A Study on Propagation Models for 60 GHz Signals in Indoor Environments

The millimeter-waves band will enable multi-gigabit data transmission due to the large available bandwidth and it is a promising solution for the spectrum scarcity below 6 GHz in future generations of mobile networks. In particular, the 60 GHz band will play a crucial role in providing high-capacity data links for indoor applications. In this context, this tutorial presents a comprehensive review of indoor propagation models operating in the 60 GHz band, considering the main scenarios of interest. Propagation mechanisms such as reflection, diffraction, scattering, blockage, and material penetration, as well as large-scale path loss, are discussed in order to obtain a channel model for 60 GHz signals in indoor environments. Finally, comparisons were made using data obtained from a measurement campaign available in the literature in order to emphasize the importance of developing accurate channel models for future wireless communication systems operating in millimeter-waves bands.

c-Axis-tilted ScAlN films grown on silicon substrates for surface acoustic wave devices

ScAlN films are currently being investigated for their potential use in surface acoustic wave (SAW) devices for next-generation mobile networks because of their high piezoelectricity. This paper describes the numerical simulation of SAW propagation in c-axis-tilted ScAlN films on silicon substrates and a fabrication technique for preparing c-axis-tilted ScAlN films on silicon substrates. The electromechanical coupling coefficient K 2 of SAW propagating in the ScAlN film/silicon substrate increased due to the c-axis tilt angle. The maximum K 2 value is approximately 3.90%. This value is 2.6 times the maximum K 2 value of the c-axis-oriented ScAlN film/silicon substrate structure. The c-axis-tilted ScAlN films with an Sc concentration of 40% were prepared on a silicon substrate via RF magnetron sputtering based on the self-shadowing effect, and the maximum c-axis tilt angle was 57.4°. These results indicate that this device structure has potential for SAW device applications with well-established micromachining technology derived from silicon substrates.

A review of teleradiology in Africa – Towards mobile teleradiology in Nigeria

eHealth is promoted as a means to strengthen health systems and facilitate universal health coverage. Sub-components (e.g. telehealth, telemedicine, mhealth) are seen as mitigators of healthcare provider shortages and poor rural and remote access. Teleradiology (including mobile teleradiology), widespread in developed nations, is uncommon in developing nations. Decision- and policy-makers require evidence to inform their decisions regarding implementation of mobile teleradiology in Nigeria and other sub-Saharan countries. To gather evidence, Scopus and PubMed were searched using defined search strings (September 2020). Duplicates were removed, and titles and abstracts reviewed using specified selection criteria. Full-text papers of selected resources were retrieved and reviewed against the criteria. Insight from included studies was charted for eight a priori categories of information: needs assessment, implementation, connectivity, evaluation, costing, image display, image capture and concordance. Fifty-seven articles were identified, duplicates removed and titles and abstracts of remaining articles reviewed against study criteria. Twenty-six papers remained. After review of full-texts, ten met the study criteria. These were summarised, and key insights for the eight categories were charted. Few papers have been published on teleradiology in sub-Saharan Africa. Teleradiology, including mobile teleradiology, is feasible in sub-Saharan Africa for routine X-ray support of patients and healthcare providers in rural and remote locations. Former technical issues (image quality, transmission speed, image compression) have been largely obviated through the high-speed, high-resolution digital imaging and network transmission capabilities of contemporary smartphones and mobile networks, where accessible. Comprehensive studies within the region are needed to guide the widespread introduction of mobile teleradiology.

Efficient Ray Tracing of Large 3D Scenes for Mobile Distributed Computing Environments

Cluster computing has attracted much attention as an effective way of solving large-scale problems. However, only a few attempts have been made to explore mobile computing clusters that can be easily built using commodity smartphones and tablets. To investigate the possibility of mobile cluster-based rendering of large datasets, we developed a mobile GPU ray tracer that renders nontrivial 3D scenes with many millions of triangles at an interactive frame rate on a small-scale mobile cluster. To cope with the limited processing power and memory space, we first present an effective 3D scene representation scheme suitable for mobile GPU rendering. Then, to avoid performance impairment caused by the high latency and low bandwidth of mobile networks, we propose using a static load balancing strategy, which we found to be more appropriate for the vulnerable mobile clustering environment than a dynamic strategy. Our mobile distributed rendering system achieved a few frames per second when ray tracing 1024 × 1024 images, using only 16 low-end smartphones, for large 3D scenes, some with more than 10 million triangles. Through a conceptual demonstration, we also show that the presented rendering scheme can be effectively explored for augmenting real scene images, captured or perceived by augmented and mixed reality devices, with high quality ray-traced images.

Enabling Intelligence in Spectrum Sharing

We argue that the capital expenditures made by an individual mobile network operator is extremely high and risky. Also, radio spectrum sharing still lacks intelligence in the current architecture of mobile networks and needs to be rethought. We propose that the goal for a disruptive innovation, in the future mobile network architecture, that shall be able to free mobile network operators from having to hold spectrum licenses and natively enable intelligent radio spectrum sharing among multiple mobile network operators. On the basis of the design principles, the duty of a single mobile network operator is split into two roles, one focuses on infrastructure development, the other only contains authorizations on the radio spectrum usage. We introduce a new role to the mobile network architecture, named Spectrum Trader, is a primary broker for spectrum trading, and it is used to coordinate with the demand-side requests and the supply-side resources to drive demand in a \emph{real-time bidding} manner. We also introduce a spectrum embedding technique that shall enable efficient and intelligent spectrum allocation by recommending the right spectrum bands based on user scenario. Finally, several significant challenges that need to be addressed in practical deployment are investigated.

Enabling Intelligence in Spectrum Sharing

We argue that the capital expenditures made by an individual mobile network operator is extremely high and risky. Also, radio spectrum sharing still lacks intelligence in the current architecture of mobile networks and needs to be rethought. We propose that the goal for a disruptive innovation, in the future mobile network architecture, that shall be able to free mobile network operators from having to hold spectrum licenses and natively enable intelligent radio spectrum sharing among multiple mobile network operators. On the basis of the design principles, the duty of a single mobile network operator is split into two roles, one focuses on infrastructure development, the other only contains authorizations on the radio spectrum usage. We introduce a new role to the mobile network architecture, named Spectrum Trader, is a primary broker for spectrum trading, and it is used to coordinate with the demand-side requests and the supply-side resources to drive demand in a \emph{real-time bidding} manner. We also introduce a spectrum embedding technique that shall enable efficient and intelligent spectrum allocation by recommending the right spectrum bands based on user scenario. Finally, several significant challenges that need to be addressed in practical deployment are investigated.