Joint Trajectory and Resource Optimization of MEC-Assisted UAVs in Sub-THz Networks: A Resources-based Multi-Agent Proximal Policy Optimization DRL with Attention Mechanism

THz band communication technology will be used in the 6G networks to enable high-speed and high-capacity data service demands. However, THz-communication losses arise owing to limitations, i.e., molecular absorption, rain attenuation, and coverage range. Furthermore, to maintain steady THz-communications and overcome coverage distances in rural and suburban regions, the required number of BSs is very high. Consequently, a new communication platform that enables aerial communication services is required. Furthermore, the airborne platform supports LoS communications rather than NLoS communications, which helps overcome these losses. Therefore, in this work, we investigate the deployment and resource optimization for MEC-enabled UAVs, which can provide THz-based communications in remote regions. To this end, we formulate an optimization problem to minimize the sum of the energy consumption of both MEC-UAV and MUs and the delay incurred by MUs under the given task information. The formulated problem is a MINLP problem, which is NP-hard. We decompose the main problem into two subproblems to address the formulated problem. We solve the first subproblem with a standard optimization solver, i.e., CVXPY, due to its convex nature. To solve the second subproblem, we design a RMAPPO DRL algorithm with an attention mechanism. The considered attention mechanism is utilized for encoding a diverse number of observations. This is designed by the network coordinator to provide a differentiated fit reward to each agent in the network. The simulation results show that the proposed algorithm outperforms the benchmark and yields a network utility which is $2.22\%$, $15.55\%$, and $17.77\%$ more than the benchmarks.Comment: 13 pages, 12 figure

Planning Wireless Cellular Networks of Future: Outlook, Challenges and Opportunities

Cell planning (CP) is the most important phase in the life cycle of a cellular system as it determines the operational expenditure, capital expenditure, as well as the long-term performance of the system. Therefore, it is not surprising that CP problems have been studied extensively for the past three decades for all four generations of cellular systems. However, the fact that small cells, a major component of future networks, are anticipated to be deployed in an impromptu fashion makes CP for future networks vis-a-vis 5G a conundrum. Furthermore, in emerging cellular systems that incorporate a variety of different cell sizes and types, heterogeneous networks (HetNets), energy efficiency, self-organizing network features, control and data plane split architectures (CDSA), massive multiple input multiple out (MIMO), coordinated multipoint (CoMP), cloud radio access network, and millimetre-wave-based cells plus the need to support Internet of Things (IoT) and device-to-device (D2D) communication require a major paradigm shift in the way cellular networks have been planned in the past. The objective of this paper is to characterize this paradigm shift by concisely reviewing past developments, analyzing the state-of-the-art challenges, and identifying future trends, challenges, and opportunities in CP in the wake of 5G. More specifically, in this paper, we investigate the problem of planning future cellular networks in detail. To this end, we first provide a brief tutorial on the CP process to identify the peculiarities that make CP one of the most challenging problems in wireless communications. This tutorial is followed by a concise recap of past research in CP. We then review key findings from recent studies that have attempted to address the aforementioned challenges in planning emerging networks. Finally, we discuss the range of technical factors that need to be taken into account while planning future networks and the promising research directions that necessitates the paradigm shift to do so

Optimisation of Mobile Communication Networks - OMCO NET

The mini conference “Optimisation of Mobile Communication Networks” focuses on advanced methods for search and optimisation applied to wireless communication networks. It is sponsored by Research & Enterprise Fund Southampton Solent University. The conference strives to widen knowledge on advanced search methods capable of optimisation of wireless communications networks. The aim is to provide a forum for exchange of recent knowledge, new ideas and trends in this progressive and challenging area. The conference will popularise new successful approaches on resolving hard tasks such as minimisation of transmit power, cooperative and optimal routing

Recent Trends in Communication Networks

In recent years there has been many developments in communication technology. This has greatly enhanced the computing power of small handheld resource-constrained mobile devices. Different generations of communication technology have evolved. This had led to new research for communication of large volumes of data in different transmission media and the design of different communication protocols. Another direction of research concerns the secure and error-free communication between the sender and receiver despite the risk of the presence of an eavesdropper. For the communication requirement of a huge amount of multimedia streaming data, a lot of research has been carried out in the design of proper overlay networks. The book addresses new research techniques that have evolved to handle these challenges

Energy-efficient cooperative resource allocation for OFDMA

Energy is increasingly becoming an exclusive commodity in next generation wireless communication systems, where even in legacy systems, the mobile operators operational expenditure is largely attributed to the energy bill. However, as the amount of mobile traffic is expected to double over the next decade as we enter the Next Generation communications era, the need to address energy efficient protocols will be a priority. Therefore, we will need to revisit the design of the mobile network in order to adopt a proactive stance towards reducing the energy consumption of the network. Future emerging communication paradigms will evolve towards Next Generation mobile networks, that will not only consider a new air interface for high broadband connectivity, but will also integrate legacy communications (LTE/LTE-A, IEEE 802.11x, among others) networks to provide a ubiquitous communication platform, and one that can host a multitude of rich services and applications. In this context, one can say that the radio access network will predominantly be OFDMA based, providing the impetus for further research studies on how this technology can be further optimized towards energy efficiency. In fact, advanced approaches towards both energy and spectral efficient design will still dominate the research agenda. Taking a step towards this direction, LTE/LTE-A (Long Term Evolution-Advanced) have already investigated cooperative paradigms such as SON (self-Organizing Networks), Network Sharing, and CoMP (Coordinated Multipoint) transmission. Although these technologies have provided promising results, some are still in their infancy and lack an interdisciplinary design approach limiting their potential gain. In this thesis, we aim to advance these future emerging paradigms from a resource allocation perspective on two accounts. In the first scenario, we address the challenge of load balancing (LB) in OFDMA networks, that is employed to redistribute the traffic load in the network to effectively use spectral resources throughout the day. We aim to reengineer the load-balancing (LB) approach through interdisciplinary design to develop an integrated energy efficient solution based on SON and network sharing, what we refer to as SO-LB (Self-Organizing Load balancing). Obtained simulation results show that by employing SO-LB algorithm in a shared network, it is possible to achieve up to 15-20% savings in energy consumption when compared to LTE-A non-shared networks. The second approach considers CoMP transmission, that is currently used to enhance cell coverage and capacity at cell edge. Legacy approaches mainly consider fundamental scheduling policies towards assigning users for CoMP transmission. We build on these scheduling approaches towards a cross-layer design that provide enhanced resource utilization, fairness, and energy saving whilst maintaining low complexity, in particular for broadband applications

Aspects of Critical Communications in Disturbance Scenarios

Infrastructures are the foundations of modern societies. The most important ones are the so-called critical infrastructures: mobile networks and electricity networks. If these networks are damaged or otherwise unavailable, the functionality of the whole society is at risk and can result even in public safety hazards. Furthermore, people expect all the time ubiquitous access to internet through mobile networks as many services rely on these wireless networks. The dependence is growing all the time as the number of worldwide subscriptions has already exceeded the world population and the amount of internet of things (IoT) and other connected devices continues to increase exponentially.This thesis focuses on the critical communications aspects of mobile networks during disturbance scenarios. These are defined as situations where, e.g. there is a power blackout in the electricity network, which affects the functionality of the mobile network.The contributions of this thesis can be divided into three main themes. The first one is the actual functionality of mobile networks during disturbance scenarios. This includes finding out how the behavior of subscribers changes when there is an uncommon disturbance scenario in the mobile network and how to prolong the disturbance time functionality of the existing networks. The results show that subscribers utilize mobile networks more than usual already before the power blackout starts when they try to find out information about the status of an upcoming storm. Immediately after the disturbance scenario starts, the subscribers within the blackout area are more active as the statistics show 73 % increase in the number of new calls and 84 % in the amount of short message service (SMS) messages. The results show also that the majority of mobile network availability is lost after 3–4 hours from the start of the incident. In order to prolong this availability time, simulations are performed to find out how utilizing only a portion of the available base station (BS) sites affects the service coverage. The results show that around 20 % of BS sites would be enough to cover 75 % of the original service coverage. Therefore, the operational time of the so-called mobile network backup coverage could be increased several times given that core network (CN) and backhaul network are also operational.The second main theme in this thesis presents a new developed situation awareness system (SAS) that combines the outage information of both mobile and electricity networks. This is an important tool for monitoring the networks and performing disaster and disturbance management. The user interface of the developed SAS is a map view showing the outage information, i.e. the faults, in both networks. It utilizes operational data from both networks such as the coverage outage areas of the mobile network and the outages of transformers in the electricity network in near real-time. The developed SAS helps to prioritize maintenance and repair work to the most critical areas as well as help to form a better overall situation awareness that fire and rescue services and authorities could utilize for improving public safety actions.The last main theme in the thesis considers innovative solutions in order to find out methods to improve the performance, i.e., to mitigate the outage of mobile networks in disturbance scenarios. The three different approaches presented are the indirect guidance of subscribers, the concept of a temporary low altitude platform (LAP) network with the help of drones, and the concept of a macro sensor network (MSN). First, the energy and capacity aspects of mobile networks can be improved when the subscribers are indirectly guided to self-optimize their location in the serving cell area. This can result in serving more user equipment (UEs) within a cell or to decrease the amount of energy needed for transmissions. Next, the coverage aspects of a LAP system are studied in order to find out the suitability of forming a temporary emergency coverage with a wireless local area network (WLAN) equipped drones. The results show that this kind of approach could provide a suitable emergency coverage for a limited area with a reasonable number of drones. Finally, a framework for MSN is studied to investigate the possibility of bringing wireless sensor network (WSN) functionalities into mobile networks. The results show that the concept of MSN could remarkably improve the resilience of mobile networks in situations where the backhaul connection is broken. However, implementing and further developing this kind of functionality will require changes in the 3rd Generation Partnership Project (3GPP) specifications and self-organizing network (SON) features within the network.Overall, this thesis provides insight on how to develop the current and future mobile networks toward more resilient infrastructures. It highlights the importance of critical communications as a fundamental part of modern societies. Thus, securing the functionality and performance of mobile networks in all situations is crucial. As a result, the contributions in this thesis can be utilized as a starting point in the future research to develop new functionalities for mobile networks. One of such approaches can be a safety mode, which would improve the mobile network resiliency during disasters and disturbance scenarios

User Association in 5G Networks: A Survey and an Outlook

26 pages; accepted to appear in IEEE Communications Surveys and Tutorial