15 research outputs found
Optimal Meshing Degree Performance Analysis in a mmWave FWA 5G Network Deployment
Fifth-generation technologies have reached a stage where it is now feasible to consider deployments that extend beyond traditional public networks. Central to this process is the application of Fixed Wireless Access (FWA) in 5G Non-public Networks (NPNs) that can utilise a novel combination of radio technologies to deploy an infrastructure on top of 5G NR or entirely from scratch. However, the use of FWA backhaul faces many challenges in relation to the trade-offs for reduced costs and a relatively simple deployment. Specifically, the use of meshed deployments is critical as it provides resilience against a temporary loss of connectivity due to link errors. In this paper, we examine the use of meshing in a FWA backhaul to determine if an optimal trade-off exists between the deployment of more nodes/links to provide multiple paths to the nearest Point of Presence (POP) and the performance of the network. Using a real 5G NPN deployment as a basis, we have conducted a simulated analysis of increasing network densities to determine the optimal configuration. Our results show a clear advantage for meshing in general, but there is also a performance trade-off to consider between overall network throughput and stability
Performance analysis of wireless mesh networks for underground mines
Abstract: Underground mines are harsh environments that have unique challenges that limit wireless communication. To ensure the safety and efficiency of mining operations, communication systems play a vital role. Despite the major developments in communication technologies, underground mines are still challenging environments for wireless communication, however, the advent of wireless mesh networks offers a cutting-edge solution to the mining industry and understanding the performance of this technology is fundamental to its application in dynamic areas of underground mines. This research project aims at conducting a performance analysis of wireless mesh networks by developing a prototype system set up of wireless mesh transceivers to conduct a feasibility study of data transmission on the network in underground mines. The second aspect of this study investigates network parameters, such as latency, throughput, and signal-to-noise, as a function of increasing mesh nodes on the network and internode spacing of mesh nodes. By combining theoretical models with real-time performance of the mesh system, realistic conclusions and better recommendations can be given to mining companies with regards to deploying wireless mesh systems in their underground mines.M.Ing. (Electrical and Electronic Engineering Science
Optimal and Approximation Algorithms for Joint Routing and Scheduling in Millimeter-Wave Cellular Networks
Millimeter-wave (mmWave) communication is a promising technology to cope with
the exponential increase in 5G data traffic.
Such networks typically require a very dense deployment of base stations.
A subset of those, so-called macro base stations, feature high-bandwidth
connection to the core network, while relay base stations are connected
wirelessly.
To reduce cost and increase flexibility, wireless backhauling is needed to
connect both macro to relay as well as relay to relay base stations.
The characteristics of mmWave communication mandates new paradigms for
routing and scheduling.
The paper investigates scheduling algorithms under different interference
models.
To showcase the scheduling methods, we study the maximum throughput fair
scheduling problem. Yet the proposed algorithms can be easily extended to other
problems.
For a full-duplex network under the no interference model, we propose an
efficient polynomial-time scheduling method, the {\em schedule-oriented
optimization}. Further, we prove that the problem is NP-hard if we assume
pairwise link interference model or half-duplex radios.
Fractional weighted coloring based approximation algorithms are proposed for
these NP-hard cases.
Moreover, the approximation algorithm parallel data stream scheduling is
proposed for the case of half-duplex network under the no interference model.
It has better approximation ratio than the fractional weighted coloring based
algorithms and even attains the optimal solution for the special case of
uniform orthogonal backhaul networks.Comment: accepted for publish in the IEEE/ACM Transactions on Networkin
Max-Min Fair Resource Allocation in Millimetre-Wave Backhauls
5G mobile networks are expected to provide pervasive high speed wireless
connectivity, to support increasingly resource intensive user applications.
Network hyper-densification therefore becomes necessary, though connecting to
the Internet tens of thousands of base stations is non-trivial, especially in
urban scenarios where optical fibre is difficult and costly to deploy. The
millimetre wave (mm-wave) spectrum is a promising candidate for inexpensive
multi-Gbps wireless backhauling, but exploiting this band for effective
multi-hop data communications is challenging. In particular, resource
allocation and scheduling of very narrow transmission/ reception beams requires
to overcome terminal deafness and link blockage problems, while managing
fairness issues that arise when flows encounter dissimilar competition and
traverse different numbers of links with heterogeneous quality. In this paper,
we propose WiHaul, an airtime allocation and scheduling mechanism that
overcomes these challenges specific to multi-hop mm-wave networks, guarantees
max-min fairness among traffic flows, and ensures the overall available
backhaul resources are fully utilised. We evaluate the proposed WiHaul scheme
over a broad range of practical network conditions, and demonstrate up to 5
times individual throughput gains and a fivefold improvement in terms of
measurable fairness, over recent mm-wave scheduling solutions
A Free Space Optic/Optical Wireless Communication: A Survey
The exponential demand for the next generation of services over free space optic and wireless optic communication is a necessity to approve new guidelines in this range. In this review article, we bring together an earlier study associated with these schemes to help us implement a multiple input/multiple output flexible platform for the next generation in an efficient manner. OWC/FSO is a complement clarification to radiofrequency technologies. Notably, they are providing various gains such as unrestricted authorizing, varied volume, essential safekeeping, and immunity to interference.
Resource management in future mobile networks: from millimetre-wave backhauls to airborne access networks
The next generation of mobile networks will connect vast numbers of devices and
support services with diverse requirements. Enabling technologies such as millimetre-wave
(mm-wave) backhauling and network slicing allow for increased wireless capacities
and logical partitioning of physical deployments, yet introduce a number of
challenges. These include among others the precise and rapid allocation of network
resources among applications, elucidating the interactions between new mobile networking
technology and widely used protocols, and the agile control of mobile infrastructure,
to provide users with reliable wireless connectivity in extreme scenarios.
This thesis presents several original contributions that address these challenges.
In particular, I will first describe the design and evaluation of an airtime allocation
and scheduling mechanism devised specifically for mm-wave backhauls, explicitly addressing
inter-flow fairness and capturing the unique characteristics of mm-wave communications.
Simulation results will demonstrate 5x throughput gains and a 5-fold
improvement in fairness over recent mm-wave scheduling solutions. Second, I will
introduce a utility optimisation framework targeting virtually sliced mm-wave backhauls
that are shared by a number of applications with distinct requirements. Based
on this framework, I will present a deep learning solution that can be trained within
minutes, following which it computes rate allocations that match those obtained with
state-of-the-art global optimisation algorithms. The proposed solution outperforms a
baseline greedy approach by up to 62%, in terms of network utility, while running
orders of magnitude faster. Third, the thesis investigates the behaviour of the Transport
Control Protocol (TCP) in Long-Term Evolution (LTE) networks and discusses
the implications of employing Radio Link Control (RLC) acknowledgements under
different link qualities, on the performance of transport protocols. Fourth, I will introduce
a reinforcement learning approach to optimising the performance of airborne cellular
networks serving users in emergency settings, demonstrating rapid convergence
(approx. 2.5 hours on a desktop machine) and a 5dB improvement of the median
Signal-to-Noise-plus-Interference-Ratio (SINR) perceived by users, over a heuristic
based benchmark solution. Finally, the thesis discusses promising future research directions
that follow from the results obtained throughout this PhD project
Channel parameter tuning in a hybrid Wi-Fi-Dynamic Spectrum Access Wireless Mesh Network
This work addresses Channel Assignment in a multi-radio multi-channel (MRMC) Wireless Mesh Network (WMN) using both Wi-Fi and Dynamic Spectrum Access (DSA) spectrum bands and standards. This scenario poses new challenges because nodes are spread out geographically so may have differing allowed channels and experience different levels of external interference in different channels. A solution must meet two conflicting requirements simultaneously: 1) avoid or minimise interference within the network and from external interference sources, and 2) maintain connectivity within the network. These two requirements must be met while staying within the link constraints and the radio interface constraints, such as only assigning as many channels to a node as it has radios. This work's original contribution to the field is a unified framework for channel optimisation and assignment in a WMN that uses both DSA and traditional Wi-Fi channels for interconnectivity. This contribution is realised by providing and analysing the performance of near-optimal Channel Assignment (CA) solutions using metaheuristic algorithms for the MRMC WMNs using DSA bands. We have created a simulation framework for evaluating the algorithms. The performance of Simulated Annealing, Genetic Algorithm, Differential Evolution, and Particle Swarm Optimisation algorithms have been analysed and compared for the CA optimisation problem. We introduce a novel algorithm, used alongside the metaheuristic optimisation algorithms, to generate feasible candidate CA solutions. Unlike previous studies, this sensing and CA work takes into account the requirement to use a Geolocation Spectrum Database (GLSD) to get the allowed channels, in addition to using spectrum sensing to identify and estimate the cumulative severity of both internal and external interference sources. External interference may be caused by other secondary users (SUs) in the vicinity or by primary transmitters of the DSA band whose emissions leak into adjacent channels, next-toadjacent, or even into further channels. We use signal-to-interference-plus-noise ratio (SINR) as the optimisation objective. This incorporates any possible source or type of interference and makes our method agnostic to the protocol or technology of the interfering devices while ensuring that the received signal level is high enough for connectivity to be maintained on as many links as possible. To support our assertion that SINR is a reasonable criterion on which to base the optimisation, we have carried out extensive outdoor measurements in both line-of-sight and wooded conditions in the television white space (TVWS) DSA band and the 5 GHz Wi-Fi band. These measurements show that SINR is useful as a performance measure, especially when the interference experienced on a link is high. Our statistical analysis shows that SINR effectively differentiates the performance of different channels and that SINR is well correlated with throughput and is thus a good predictor of end-user experience, despite varying conditions. We also identify and analyse the idle times created by Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) contention-based Medium Access Control (MAC) operations and propose the use of these idle times for spectrum sensing to measure the SINR on possible channels. This means we can perform spectrum sensing with zero spectrum sensing delay experienced by the end user. Unlike previous work, this spectrum sensing is transparent and can be performed without causing any disruption to the normal data transmission of the network. We conduct Markov chain analysis to find the expected length of time of a sensing window. We also derive an efficient minimum variance unbiased estimator of the interference plus noise and show how the SINR can be found using this estimate. Our estimation is more granular, accurate, and appropriate to the problem of Secondary User (SU)-SU coexistence than the binary hypothesis testing methods that are most common in the literature. Furthermore, we construct confidence intervals based on the probability density function derived for the observations. This leads to finding and showing the relationships between the number of sampling windows and sampling time, the interference power, and the achievable confidence interval width. While our results coincide with (and thus are confirmed by) some key previous recommendations, ours are more precise, granular, and accurate and allow for application to a wider range of operating conditions. Finally, we present alterations to the IEEE 802.11k protocol to enable the reporting of spectrum sensing results to the fusion or gateway node and algorithms for distributing the Channel Assignment once computed. We analyse the convergence rate of the proposed procedures and find that high network availability can be maintained despite the temporary loss of connectivity caused by the channel switching procedure. This dissertation consolidates the different activities required to improve the channel parameter settings of a multi-radio multi-channel DSA-WMN. The work facilitates the extension of Internet connectivity to the unconnected or unreliably connected in rural or peri-urban areas in a more cost-effective way, enabling more meaningful and affordable access technologies. It also empowers smaller players to construct better community networks for sharing local content. This technology can have knock-on effects of improved socio-economic conditions for the communities that use it
Enabling Technology in Optical Fiber Communications: From Device, System to Networking
This book explores the enabling technology in optical fiber communications. It focuses on the state-of-the-art advances from fundamental theories, devices, and subsystems to networking applications as well as future perspectives of optical fiber communications. The topics cover include integrated photonics, fiber optics, fiber and free-space optical communications, and optical networking