Handoffs in Cellular Wireless Networks: The Daedalus Implementation and Experience

To guarantee the real-time transmission for time-sensitive traffic, we need to take delay-bound quality-of-service (QoS) into account when designing the wireless cellular networks. The traditional powerful QoS guarantee technique, called the homogeneous statistical QoS provisioning, assumes that the QoS provisioning of each link can be individually processed. In order to further significantly increase the global system throughput, the available resources of all links need to be jointly controlled, which is typically suitable for downlink transmissions over wireless cellular networks. Under this setup, we need to consider the diverse delay-bound QoS provisionings for different links at the same time, which represents the new heterogeneous statistical QoS provisioning framework and imposes many new challenges not encountered before in wireless networks. To overcome these problems, in this paper we propose the heterogeneous statistical QoS provisioning framework for high-speed downlink transmissions in wireless cellular networks. In particular, we formulate the optimization problem to maximize the downlink throughput subject to heterogeneous statistical delay-bound QoS requirements. For solving this optimization problem, we develop the heterogeneous-QoS-driven power allocation scheme to derive the closed-form solutions which can maximize the global system throughput while guaranteeing the heterogeneous delay-bound QoS for the entire wireless cellular networks. We show that the heterogeneous-QoS-driven power allocation provides more generic framework for downlink transmissions. The extensive simulation results obtained show that our proposed heterogeneous-QoS-driven power allocation scheme can achieve the global optimization of wireless resource efficiency, thus significantly increasing the global system throughput as compared with the homogeneous statistical delay-bound QoS provisioning schemes.

Analytic modeling of handoffs in wireless cellular networks

In this paper, NPS (neural-network prediction scheme) is proposed to provide high accurate location prediction of a MH (mobile host) in wireless networks. Currently, multimedia communications is urgently expected in wireless networks, because more and more high-speed applications emerge for wireless networks. One of the most important and complicated issues is quality of service (QoS) in third-generation (3G) wireless networks. In other words, the problem to maintain the playing continuity of multimedia streams during a handoff is hard to solve. Hence, bandwidth reservation scheme is proposed in this paper. In order to avoid too early or over reservation resulting in a waste of resources, we present a method called three-times resource-reservation scheme (TTRR) to let reserved resource become really active upon MH entering into tier-2 [C.H. Choi et al., 2000] area of a cell. NPS and TTRR can efficiently improve the accuracy of MH's trajectory prediction, increase the success probability of resource reservation, and enhance bandwidth utilization.

In recent work, we have introduced MI-MAC (Multimedia Integration Multiple Access Control), a new access control protocol for wireless cellular networks. MI-MAC was shown to be a good candidate for next generation wireless cellular networks, due to its superior performance in comparison to other (TDMA and WCDMA-based) protocols in the literature when integrating various types of multimedia traffic. In the present work we proceed further with the study of MI-MAC's efficiency, by evaluating its ability to efficiently integrate streams from latest technology video encoders with other types of packet traffic over noisy wireless networks. To the best of our knowledge, this is one of the first works in the literature to study the integration of H.264 streams with other types of multimedia traffic over wireless cellular networks.

Interactive transparent networking–modeling examples of snoop and WTCP protocols

Several solutions have been proposed for improving the Quality of Service (QoS) in wireless cellular networks, such as Call Admission Control (CAC) and handover strategies. However, none of them considers the usage of different interfaces for different conditions. In this work, we propose a Fuzzy-Based Multi-Interface System (FBMIS), where each node is equipped with two interfaces: the traditional cellular network interface and Mobile Ad hoc Networks (MANET)interface. The proposed FBMIS system is able to switch from cellular to ad-hoc mode and vice versa. We consider four input parameters: Distance Between Nodes (DBN), Node Mobility (NM), Angle between Node and Base station (ANB), and User Request Security (URS). We evaluated the performance of the proposed system by computer simulations using MATLAB. The simulation results show that our system has a good performance.

Now-a-days wireless network is providing ubiquitous communication services to a vast number of mobile users. The most salient feature of wireless network is mobility support, which enables mobile users to communicate with others regardless of location. The important design criteria in wireless networks are to support guaranteed quality of services (QoS) to mobile users. The handover management and location management is one such QoS parameter for the wireless network. In this paper, we propose user profile based (UPB) scheme to provide reliable location tracking of user in case of VLR overloading or congestion in network or any other problem when we need to check the VLR. UPB is based on historical movement information of user. We have also taken a Random Searching Technique (RST) and Sequential Search Technique (SST) to compare UPB. In RST scheme, searching of cell is design in a random order and SST is design in ascending order. Our analyses reduce no. of search and average waiting time of mobile subscriber when searching of user is based on UPB.

In this paper, NPS (neural network prediction scheme) is proposed to provide high accuracy location prediction of mobile host (MH) in target cell. Multimedia communications is urgently expected in wireless networks. One of the most important and complicated issues is quality of service guarantees in third-generation (3G) wireless networks. In other words, the problem to maintain the continuity of multimedia playing during the handoff is hard to solve. In order to avoid too early or over reservation resulting in a waste of resources, in this study, we present a method called TTRR (three times resource reservation scheme), to let reserved resource become really active upon MH entering into tire-2 (C.H. Choi, et al., Nov. 2000) area of cell. NSP and TTRR can efficiently improve the accuracy of MHs trajectory prediction, increase the success probability of resource reservation, and enhance bandwidth utilization.

Predictive channel reservation for handoff prioritization in wireless cellular networks

Effective support of real‐time multimedia applications in wireless access networks, viz. cellular networks and wireless LANs, requires a dynamic bandwidth adaptation framework where the bandwidth of an ongoing call is continuously monitored and adjusted. Since bandwidth is a scarce resource in wireless networking, it needs to be carefully allocated amidst competing connections with different Quality of Service (QoS) requirements. In this paper, we propose a new framework called QoS‐adaptive multimedia wireless access (QoS‐AMWA) for supporting heterogeneous traffic with different QoS requirements in wireless cellular networks. The QoS‐AMWA framework combines the following components: (i) a threshold‐based bandwidth allocation policy that gives priority to handoff calls over new calls and prioritizes between different classes of handoff calls by assigning a threshold to each class, (ii) an efficient threshold‐type connection admission control algorithm, and (iii) a bandwidth adaptation algorithm that dynamically adjusts the bandwidth of an ongoing multimedia call to minimize the number of calls receiving lower bandwidth than the requested. The framework can be modeled as a multi‐dimensional Markov chain, and therefore, a product‐form solution is provided. The QoS metrics—new call blocking probability (NCBP), handoff call dropping probability (HCDB), and degradation probability (DP)—are derived. The analytical results are supported by simulation and show that this work improves the service quality by minimizing the handoff call dropping probability and maintaining the bandwidth utilization efficiently. Copyright © 2006 John Wiley & Sons, Ltd.

Wireless communications along with portable computers, digital assistants and sensor devices provide a pervasive base for mobile computing. However realizing truly ubiquitous mobile computing requires innovative theories, paradigms and applications in various research areas including algorithms, networking, software architectures and data management. Topic 14 covers all such aspects. This topic attracted 33 submissions showing the increasing interest in the field. From the submitted papers, 8 were accepted as full papers (24% acceptance rate). The selected papers cover various aspects of mobile and ubiquitous computing highlighting the diversity of the field and thus making up an interesting and stimulating track.Paper presentations are divided into three sessions. Two papers in the first session address consistency issues. In “Efficient and Fault-Tolerant Update Commitment for Weakly Connected Replication”, J. Barreto and P. Ferreira propose a novel epidemic weighted voting protocol for achieving eventual consistency in optimistic replication that allows multiple update candidates in an election. In “Controlling Concurrency in Mobile Computing Environments with Broadcast-based Dissemination”, J. M. Monteiro and A. Brayner present a new serializability-based protocol for ensuring data consistency and currency when data are disseminated to clients through wireless broadcast. The last paper in this session, “Integrating Mobile Devices into the Grid: Design Considerations and Evaluation” by S. Isaiadis and V. Getov, discusses implementation and performance issues for integrating mobile devices into the grid. The second session is shared with Topic 8. The two papers address aspects related to frequency utilization in wireless networking. In “New Bounds on the Competitiveness of Randomized Online Call Control in Cellular Networks”, I. Karagiannis, C. Kaklamanis and E. Papaioannou present new upper and lower bounds for the online version of the call control problem in wireless cellular networks. In “A Multiple Channel Access Protocol for Ad Hoc Wireless Networks”, K-W. Jang considers the problem of enhancing channel utilization in wireless ad hoc networks through channel exchange between neighboring nodes. In the last session, in “Personalized Access to Semantic Web Agents Using Smart Cards”, R. C. Erdur and G. Kardas argue for storing personal information on smart cards. The other two papers focus on secure networking. K. Kim, J. Hong and J. Lim present a “Fast and Secure Communication Resume Protocol” to speed up connection resume after a communication error. In “On AAA with Extended IDK in Mobile IP Networks”, H. Jeon, M. Y. Chung and H. Choo discuss how to attain fast and secure mobile IP networking by addressing problems of the hand-off process in a secure way.

There is great interest in considering the energy efficiency aspect of wireless cellular networks. When a wireless cellular network is powered by the smart grid, only considering energy efficiency in the cellular network is not enough. In this paper, we consider not only energy-efficient communications but also the dynamics of the smart grid in operating green wireless cellular networks. We formulate the system as a two-level Stackelberg game. A backward induction method is used to analyze the proposed scheme. we prove that the Stackelberg equilibrium (SE) of the proposed game exists and is unique. An iteration algorithm is proposed to obtain the SE. Simulation results show that the smart grid has a significant impact on green wireless cellular networks, and our proposed scheme can significantly reduce operational expenditure and CO2 emissions in green wireless cellular networks.

This chapter describes the support for IP based multimedia services on Third Generation (3G) wireless cellular networks. While earlier cellular networks offered only basic IP connectivity on a best-effort basis, 3G networks provide explicit support for real time multimedia services with guaranteed Quality of Service (QoS). As a result, they can offer traditional voice telephony, rich telephony services and multimedia streaming over IP, both inside a 3G network and in conjunction with external networks such as the Internet, the Public Switched Telephone Network (PSTN) and the Integrated Services Digital Network (ISDN). In fact, 3G networks will deploy for the first time in a large scale technologies such as IP version 6 (IPv6) and policy based IP QoS, spearheading the introduction of such technologies into the Internet. The two most important aspects of 3G networks with respect to IP based multimedia services are the IP Multimedia Subsystem (IMS) and the Multimedia Broadcast / Multicast Service (MBMS). The IMS enables complex IP based multimedia sessions to be created with guaranteed QoS for each media component. Example applications include voice telephony and video conferencing. The IMS interoperates with both traditional telephony services and external IP based multimedia services. The MBMS provides native IP broadcast and multicast support in 3G networks, allowing high bandwidth services to be economically offered to multiple users. Example applications include video streaming via multicast and location based services via broadcast. The MBMS interoperates directly with IP multicasting. While both the IMS and the MBMS are IP based, their standardization is proceeding independently. It is however clear that their combination would allow numerous new services to be provided. The outline of this chapter is as follows. In Section II we give an overview of cellular networks and their evolution, while in Section III we describe in detail a specific 3G network, the Universal Mobile Telecommunications System (UMTS). Section IV presents an introductory description of the features and services provided by the IMS and the MBMS. In Section V we provide the details of the IMS, including service architecture, session setup and control and interworking issues. Section VI describes the MBMS in the same manner as for the IMS. Finally, Section VII discusses the QoS issues for IP based multimedia services, describing the overall QoS concept, the policy based QoS control scheme and its application to IMS sessions. At the end of the chapter, Tables II and III list the acronyms used. An extensive UMTS vocabulary is provided in [1].

In this paper we address the issue of cross-layer design in transport layer enhancement mechanisms, where the data-link and transport layer information is shared with each other, in order to provide improved system throughput of the wireless cellular network. We propose a cross-layer transport layer enhancement mechanism with name of XST (cross-layer snoop protocol for TCP), which is based on Snoop protocol combined with the forced duplicate acknowledgement congestion control strategy in wireless cellular networks. XST employs the cross-layer design, working at the data-link layer but using the transport layer information as operating criteria. We conduct a comparative study between the XST mechanism and active queue management (AQM) mechanism in the literature, such as random early detection (RED) in wireless environments with varying link characteristics. Simulation results demonstrate that the proposed XST significantly outperforms RED in wireless cellular network, especially under high-error-rate which is a major characteristic of wireless links.

In wireless cellular networks or in other networks with single-hop communication, the fundamental access control problem pertains to access point (AP) selection and channel allocation for each user. For users in the coverage area of one AP, this involves only channel allocation. However, users that belong in the intersection of coverage areas of more than one AP can select the appropriate AP to establish connection and implicitly affect the channel assignment procedure. We address the joint problem of AP selection and channel assignment with the objective to satisfy a given user load vector with the minimum number of channels. Our major finding is that the joint problem reduces to plain channel allocation in a cellular network that emerges from the original one after executing an iterative and provably convergent clique load balancing algorithm. For linear cellular networks, our approach leads to minimum number of required channels to serve a given load vector. For 2D cellular networks, the same approach leads to a heuristic algorithm with a suboptimal solution due to the fact that clique loads cannot be balanced. Numerical results demonstrate the performance benefits of our approach in terms of blocking probability in a dynamic scenario with time-varying number of connection requests. The presented approach constitutes the basis for addressing more composite resource allocation problems in different context.