Vertex-linked infrastructure for ad hoc networks

An ad hoc network is composed of geographically dispersed nodes that may move arbitrarily and communicate with each other without the support of a stationary infrastructure. Compared with a wireless network with a stationary infrastructure, such as a cellular network, an ad hoc network is inherently less efficient. Therefore, a number of proposals have been made to develop a quasi-stationary infrastructure for ad hoc networks. However, the dynamic nature of ad hoc networks makes it very costly to maintain such an infrastructure. This article proposes a Vertex-Linked Infrastructure (VLI) for ad hoc networks. This novel approach uses an easily deployable, survivable, wired infrastructure as a backbone of the ad hoc network, thus realizing the advantages of an infrastructure in wireless communications, but without the overhead due to maintaining such an infrastructure.published_or_final_versio

Networks of queues: myth and reality

Jackson’s theorem, which is the basis of the mathematical theory of networks of queues, does not hold.published_or_final_versio

Personal information service (PIS)-an application of wide-band communications, 2012 A.D.

With the affluence that comes with economic developments and technological advances, citizens around the world will require personalized, on-demand, high-quality information services, which the author calls personal information service (PIS). He foresees that by 2012 A.D., a variety of communication services, and in particular PIS, will be much more widely available around the world. To make such services available to the masses, a number of challenges have to be overcome. In this paper, the author addresses the challenges. He believes that by working together solutions can be obtained by 2012 A.D.published_or_final_versio

A queue with multiple stable regions

Proceedings of the UKPEW, 2009, p. 75-83The stable region of a queue consists of all values of the system parameters for the queue to be stable. A queue can have multiple stable regions, such that the probability law governing the system has different functional forms in different stable regions and hence the performance of the system cannot be captured only by the parameter values. We analyze a queue with multiple stable regions, and explain why such a queue is not amenable to current queueing theory.postprin

A framework for balancing information collection and data transmission

Network protocol performance is closely related to knowledge about the network state. However, acquiring such knowledge expends network bandwidth resource. Thus a trade off exists between the amount of bandwidth resource expended in acquiring knowledge about network state, and the improved protocol performance due to such knowledge. Previous work used rate distortion theory to calculate the minimum information required for certain network performance. However, this limit is asymptotic and might not be achievable due to the introduced infinite delay. This work develops a non-asymptotic framework to find a practical bound of the required information for certain network performance, and the strategies for implementing network information collection. The framework is illustrated by a wireless scheduling problem to show the quantitative relationship between collected traffic information and network throughput. Furthermore, we calculate the effective data rate by considering the overhead of network information collection, and determine the optimal resource allocation between information collection and data transmission.published_or_final_versio

Efficient resource management for end-to-end QoS guarantees in DiffServ networks

The Differentiated Services (DiffServ) architecture has been proposed as a scalable solution for delivering end-to-end Quality of Service (QoS) guarantees over the Internet. While the scalability of the data plane emerges from the definition of only a small number of different service classes, the issue of a scalable control plane is still an open research problem. The initial proposal was to use a centralized agent, called Bandwidth Broker (BB), to manage the resources within each DiffServ domain and make local admission control decisions. In this paper, we propose an alternative distributed approach, where the local admission decisions are made independently at the edge routers of each domain. We will show, through simulation results, that this distributed approach can manage the network resources very efficiently, leading to lower bandwidth blocking rates when compared to traditional shortest path admission control. Moreover, its simplicity and distributed implementation make it a very scalable solution for resource management in DiffServ networks.published_or_final_versio

Mathematical impact of information accuracy on network performance

Many wireless network protocols have to deal with inaccurate information due to the lack of sufficient knowledge of the scenario or other limitations. Therefore, in this paper, we study information accuracy and investigate its quantitative impact on wireless network performance. First, we introduce an entropy-performance framework to model the relationship between wireless network performance and entropy, which characterizes the uncertainty of the input. Under this framework, we quantify the performance variations due to the availability of side information and find that the system performance improvement has a positive linear relationship with the amount of mutual information between input and side information. Subsequently, information accuracy is proposed to reflect the reliability of information. We show that information accuracy has a natural relationship with mutual information and we quantify the impact of information accuracy on wireless network performance. ©2010 IEEE.published_or_final_versionThe 2010 IEEE International Conference on Communications (ICC 2010), Cape Town, South Africa, 23-27 May 2010. In Proceedings of ICC, 2010, p. 1-

Chemical-reaction-inspired metaheuristic for optimization

We encounter optimization problems in our daily lives and in various research domains. Some of them are so hard that we can, at best, approximate the best solutions with (meta-) heuristic methods. However, the huge number of optimization problems and the small number of generally acknowledged methods mean that more metaheuristics are needed to fill the gap. We propose a new metaheuristic, called chemical reaction optimization (CRO), to solve optimization problems. It mimics the interactions of molecules in a chemical reaction to reach a low energy stable state. We tested the performance of CRO with three nondeterministic polynomial-time hard combinatorial optimization problems. Two of them were traditional benchmark problems and the other was a real-world problem. Simulation results showed that CRO is very competitive with the few existing successful metaheuristics, having outperformed them in some cases, and CRO achieved the best performance in the real-world problem. Moreover, with the No-Free-Lunch theorem, CRO must have equal performance as the others on average, but it can outperform all other metaheuristics when matched to the right problem type. Therefore, it provides a new approach for solving optimization problems. CRO may potentially solve those problems which may not be solvable with the few generally acknowledged approaches. © 2006 IEEE.published_or_final_versio

Satellite-based internet: A tutorial

In a satellite-based Internet system, satellites are used to interconnect heterogeneous network segments and to provide ubiquitous direct Internet access to homes and businesses. This article presents satellite-based Internet architectures and discusses multiple access control, routing, satellite transport, and integrating satellite networks into the global Internet.published_or_final_versio

Distributed flow-based scheduling in multi-hop ad hoc networks

Shared channel contention-based MAC protocols, such as IEEE 802.11, are popular in ad hoc networks because of their ease of implementation. However, these contention-based MAC protocols do not coordinate between nodes at different hops within a multi-hop flow. This results in channel resource and node transmission power wastage and overall system throughput degradation. In this paper we present a novel distributed flow-based scheduling (DFBS) scheme that coordinates between neighbor links of a multi-hop flow. As demonstrated by the simulation results, DFBS achieves higher throughput and improves the transmission efficiency when traffic load is relatively high.published_or_final_versio