Multi-Cell, Multi-Channel Scheduling with Probabilistic Per-Packet Real-Time Guarantee

For mission-critical sensing and control applications such as those to be enabled by 5G Ultra-Reliable, Low-Latency Communications (URLLC), it is critical to ensure the communication quality of individual packets. Prior studies have considered Probabilistic Per-packet Real-time Communications (PPRC) guarantees for single-cell, single-channel networks with implicit deadline constraints, but they have not considered real-world complexities such as inter-cell interference and multiple communication channels. Towards ensuring PPRC in multi-cell, multi-channel wireless networks, we propose a real-time scheduling algorithm based on \emph{local-deadline-partition (LDP)}. The LDP algorithm is suitable for distributed implementation, and it ensures probabilistic per-packet real-time guarantee for multi-cell, multi-channel networks with general deadline constraints. We also address the associated challenge of the schedulability test of PPRC traffic. In particular, we propose the concept of \emph{feasible set} and identify a closed-form sufficient condition for the schedulability of PPRC traffic. We propose a distributed algorithm for the schedulability test, and the algorithm includes a procedure for finding the minimum sum work density of feasible sets which is of interest by itself. We also identify a necessary condition for the schedulability of PPRC traffic, and use numerical studies to understand a lower bound on the approximation ratio of the LDP algorithm. We experimentally study the properties of the LDP algorithm and observe that the PPRC traffic supportable by the LDP algorithm is significantly higher than that of a state-of-the-art algorithm

State-of-the-art of distributed channel assignment

Channel assignment for Wireless Mesh Networks (WMNs) attempts to increase the network performance by decreasing the interference of simultaneous transmissions. The reduction of interference is achieved by exploiting the availability of fully or partially non-overlapping channels. Although it is still a young research area, many different approaches have already been developed. These approaches can be distinguished into centralized and distributed. Centralized algorithms rely on a central entity, usually called Channel Assignment Server (CAS), which calculates the channel assignment and sends the result to the mesh routers. In distributed approaches, each mesh router calculates its channel assignment decision based on local information. Distributed approaches can react faster to topology changes due to node failures or mobility and usually introduce less protocol overhead since communication with the CAS is not necessary. As a result, distributed approaches are more suitable once the network is operational and running. Distributed approaches can further be classified into static and dynamic, in regard to the modus of channel switching. In dynamic approaches, channels can be switched on a per-packet basis, whereas in static approaches radios stay on a specific channel for a longer period of time. Static assignments have been more in focus, since the channel switching time for current Institute of Electrical and Electronics Engineers (IEEE) 802.11 hardware is in the order of milliseconds which is two orders higher than the packet transmission time. Recently, surveys of channel assignment algorithms have been presented which cover certain aspects of the research field. The survey in [1] introduces the problem and presents a couple of distributed algorithms and [2] gives a broad introduction to centralized and distributed approaches. The survey herein is focused on distributed approaches for peer- to-peer network architectures. This report describes the problem formulation for channel assignment in WMNs and the fundamental concepts and challenges of this research area. We present different distributed channel assignment algorithms and characterize them according to a set of classification keys. Since channel assignment algorithms may change the connectivity and therefore the network topology, they may have a high impact on routing. Therefore, we present routing metrics that consider channel diversity and adapt better to the multi- radio multi-channel scenario than traditional routing metrics designed for single channel networks. The presented algorithms are discussed and compared focusing on practical evaluations in testbed and network environments. The implementation for real networks is a hard and labor-intensive task because the researcher has to deal with the complexity of the hardware, operating system, and wireless network interface drivers. As a result, frameworks emerged in order to simplify the implementation process. We describe these frameworks and the mechanisms used to help researchers implementing their algorithms and show their limitations and restrictions

Hybrid routing and bridging strategies for large scale mobile ad hoc networks

Multi-hop packet radio networks (or mobile ad-hoc networks) are an ideal technology to establish instant communication infrastructure for military and civilian applications in which both hosts and routers are mobile. In this dissertation, a position-based/link-state hybrid, proactive routing protocol (Position-guided Sliding-window Routing - PSR) that provides for a flat, mobile ad-hoc routing architecture is described, analyzed and evaluated. PSR is based on the superposition of link-state and position-based routing, and it employs a simplified way of localizing routing overhead, without having to resort to complex, multiple-tier routing organization schemes. A set of geographic routing zones is defined for each node, where the purpose of the ith routing zone is to restrict propagation of position updates, advertising position differentials equal to the radius of the (i-i )th routing zone. Thus, the proposed protocol controls position-update overhead generation and propagation by making the overhead generation rate and propagation distance directly proportional to the amount of change in a node\u27s geographic position. An analytical model and framework is provided, in order to study the various design issues and trade-offs of PSR routing mechanism, discuss their impact on the protocol\u27s operation and effectiveness, and identify optimal values for critical design parameters, under different mobility scenarios. In addition an in-depth performance evaluation, via modeling and simulation, was performed in order to demonstrate PSR\u27s operational effectiveness in terms of scalability, mobility support, and efficiency. Furthermore, power and energy metrics, such as path fading and battery capacity considerations, are integrated into the routing decision (cost function) in order to improve PSR\u27s power efficiency and network lifetime. It is demonstrated that the proposed routing protocol is ideal for deployment and implementation especially in large scale mobile ad hoc networks. Wireless local area networks (WLAN) are being deployed widely to support networking needs of both consumer and enterprise applications, and IEEE 802.11 specification is becoming the de facto standard for deploying WLAN. However IEEE 802.11 specifications allow only one hop communication between nodes. A layer-2 bridging solution is proposed in this dissertation, to increase the range of 802.11 base stations using ad hoc networking, and therefore solve the hotspot communication problem, where a large number of mobile users require Internet access through an access point. In the proposed framework nodes are divided into levels based on their distance (hops) from the access point. A layer-2 bridging tree is built based on the level concept, and a node in certain level only forwards packets to nodes in its neighboring level. The specific mechanisms for the forwarding tree establishment as well as for the data propagation are also introduced and discussed. An analytical model is also presented in order to analyze the saturation throughput of the proposed mechanism, while its applicability and effectiveness is evaluated via modeling and simulation. The corresponding numerical results demonstrate and confirm the significant area coverage extension that can be achieved by the solution, when compared with the conventional 802.1 lb scheme. Finally, for implementation purposes, a hierarchical network structure paradigm based on the combination of these two protocols and models is introduced

A Hybrid (Active-Passive) VANET Clustering Technique

Clustering serves a vital role in the operation of Vehicular Ad hoc Networks (VANETs) by continually grouping highly mobile vehicles into logical hierarchical structures. These moving clusters support Intelligent Transport Systems (ITS) applications and message routing by establishing a more stable global topology. Clustering increases scalability of the VANET by eliminating broadcast storms caused by packet flooding and facilitate multi-channel operation. Clustering techniques are partitioned in research into two categories: active and passive. Active techniques rely on periodic beacon messages from all vehicles containing location, velocity, and direction information. However, in areas of high vehicle density, congestion may occur on the long-range channel used for beacon messages limiting the scale of the VANET. Passive techniques use embedded information in the packet headers of existing traffic to perform clustering. In this method, vehicles not transmitting traffic may cause cluster heads to contain stale and malformed clusters. This dissertation presents a hybrid active/passive clustering technique, where the passive technique is used as a congestion control strategy for areas where congestion is detected in the network. In this case, cluster members halt their periodic beacon messages and utilize embedded position information in the header to update the cluster head of their position. This work demonstrated through simulation that the hybrid technique reduced/eliminated the delays caused by congestion in the modified Distributed Coordination Function (DCF) process, thus increasing the scalability of VANETs in urban environments. Packet loss and delays caused by the hidden terminal problem was limited to distant, non-clustered vehicles. This dissertation report presents a literature review, methodology, results, analysis, and conclusion

Mobile Ad Hoc Networks

Guiding readers through the basics of these rapidly emerging networks to more advanced concepts and future expectations, Mobile Ad hoc Networks: Current Status and Future Trends identifies and examines the most pressing research issues in Mobile Ad hoc Networks (MANETs). Containing the contributions of leading researchers, industry professionals, and academics, this forward-looking reference provides an authoritative perspective of the state of the art in MANETs. The book includes surveys of recent publications that investigate key areas of interest such as limited resources and the mobility of mobile nodes. It considers routing, multicast, energy, security, channel assignment, and ensuring quality of service. Also suitable as a text for graduate students, the book is organized into three sections: Fundamentals of MANET Modeling and Simulation—Describes how MANETs operate and perform through simulations and models Communication Protocols of MANETs—Presents cutting-edge research on key issues, including MAC layer issues and routing in high mobility Future Networks Inspired By MANETs—Tackles open research issues and emerging trends Illustrating the role MANETs are likely to play in future networks, this book supplies the foundation and insight you will need to make your own contributions to the field. It includes coverage of routing protocols, modeling and simulations tools, intelligent optimization techniques to multicriteria routing, security issues in FHAMIPv6, connecting moving smart objects to the Internet, underwater sensor networks, wireless mesh network architecture and protocols, adaptive routing provision using Bayesian inference, and adaptive flow control in transport layer using genetic algorithms

MARIAN: A hybrid, metric-driven, agent-based routing protocol for multihop ad-hoc networks

Recent advances in technology provided the ground for highly dynamic, mobile, infrastructure-less networks, namely, ad-hoc networks. Despite their enormous benefits, the full potential cannot be reached unless certain issues are resolved. These mainly involve routing, as the lack of an infrastructure imposes a heavy burden on mobile devices that must maintain location information and route data packets in a multi-hop fashion. Specifically, typical adhoc routing devices, such as Personal Digital Assistants (PDAs), are limited in respect to the available throughput, life-time, and performance, that these may provide, as routing elements. Thus, there is a need for metric-driven ad-hoc routing, that is, devices should be utilised for routing according to their fitness, as different device types significantly vary in terms of routing fitness. In addition, a concrete agent-based approach can provide a set of advantages over a non-agent-based one, which includes: better design practice; and automatic reconfigurability.This research work aims to investigate the applicability of stationary and mobile agent technology in multi-hop ad-hoc routing. Specifically, this research proposes a novel hybrid, metric-driven, agent-based routing protocol for multi-hop ad-hoc networks that will enhance current routing schemes. The novelties that are expected to be achieved include: maximum network performance, increased scalability, dynamic adaptation, Quality of Service (QoS), energy conservation, reconfigurability, and security. The underlying idea is based on the fact that stationary and mobile agents can be ideal candidates for such dynamic environments due to their advanced characteristics, and thus offer state of the art support in terms of organising the otherwise disoriented network into an efficient and flexible hierarchical structure, classifying the routing fitness of participating devices, and therefore allow intelligent routing decisions to be taken on that basis

MARIAN: A hybrid, metric-driven, agent-based routing protocol for multihop ad-hoc networks

Recent advances in technology provided the ground for highly dynamic, mobile, infrastructure-less networks, namely, ad-hoc networks. Despite their enormous benefits, the full potential cannot be reached unless certain issues are resolved. These mainly involve routing, as the lack of an infrastructure imposes a heavy burden on mobile devices that must maintain location information and route data packets in a multi-hop fashion. Specifically, typical adhoc routing devices, such as Personal Digital Assistants (PDAs), are limited in respect to the available throughput, life-time, and performance, that these may provide, as routing elements. Thus, there is a need for metric-driven ad-hoc routing, that is, devices should be utilised for routing according to their fitness, as different device types significantly vary in terms of routing fitness. In addition, a concrete agent-based approach can provide a set of advantages over a non-agent-based one, which includes: better design practice; and automatic reconfigurability.This research work aims to investigate the applicability of stationary and mobile agent technology in multi-hop ad-hoc routing. Specifically, this research proposes a novel hybrid, metric-driven, agent-based routing protocol for multi-hop ad-hoc networks that will enhance current routing schemes. The novelties that are expected to be achieved include: maximum network performance, increased scalability, dynamic adaptation, Quality of Service (QoS), energy conservation, reconfigurability, and security. The underlying idea is based on the fact that stationary and mobile agents can be ideal candidates for such dynamic environments due to their advanced characteristics, and thus offer state of the art support in terms of organising the otherwise disoriented network into an efficient and flexible hierarchical structure, classifying the routing fitness of participating devices, and therefore allow intelligent routing decisions to be taken on that basis

Intelligent Sensor Networks

In the last decade, wireless or wired sensor networks have attracted much attention. However, most designs target general sensor network issues including protocol stack (routing, MAC, etc.) and security issues. This book focuses on the close integration of sensing, networking, and smart signal processing via machine learning. Based on their world-class research, the authors present the fundamentals of intelligent sensor networks. They cover sensing and sampling, distributed signal processing, and intelligent signal learning. In addition, they present cutting-edge research results from leading experts