Multicast Broadcast Services Support in OFDMA-Based WiMAX Systems [Advances in Mobile Multimedia]

Multimedia stream service provided by broadband wireless networks has emerged as an important technology and has attracted much attention. An all-IP network architecture with reliable high-throughput air interface makes orthogonal frequency division multiplexing access (OFDMA)-based mobile worldwide interoperability for microwave access (mobile WiMAX) a viable technology for wireless multimedia services, such as voice over IP (VoIP), mobile TV, and so on. One of the main features in a WiMAX MAC layer is that it can provide'differentiated services among different traffic categories with individual QoS requirements. In this article, we first give an overview of the key aspects of WiMAX and describe multimedia broadcast multicast service (MBMS) architecture of the 3GPP. Then, we propose a multicast and broadcast service (MBS) architecture for WiMAX that is based on MBMS. Moreover, we enhance the MBS architecture for mobile WiMAX to overcome the shortcoming of limited video broadcast performance over the baseline MBS model. We also give examples to demonstrate that the proposed architecture can support better mobility and offer higher power efficiency.     

Fast Handoff in SIP-Based Next Generation Mobile Networks

It is commonly held that next generation mobile systems will be developed on the Internet in combination with diverse access technologies, as the future network architecture will be the coming together of various overlapping wireless access networks. Integrating various wireless networks in future heterogeneous networking environments poses many difficulties, the most critical challenge of which is efficient support for seamless mobility. SIP is a promising nominee for managing mobility in heterogeneous networks as it provides mobility within the application layer and the characteristics of the lower layer protocols are invisible to it. However, the performance of SIP-based mobility management is downgraded, resulting from its adoption of TCP/UDP for signaling and its strict separation between the lower layers and the application layer of the protocol stack. In this paper, a SIP-based cross-layer design for fast handoffs is proposed to shorten the service interruption time when a mobile node crosses the overlapped area of a WLAN/3G cellular system. As will be shown by the simulation results, the SIP-based solution proposed in this paper effectively lessens the handoff delays caused by either the horizontal handoff or vertical handoff in future all-IP heterogeneous wireless networks.     

A signaling and control architecture for mobility support in wireless ATM networks

This paper presents a signaling and control architecture for mobility support in a wireless ATM network that provides integrated broadband services to mobile terminals. A system level protocol architecture for a wireless ATM network is outlined. The proposed protocol stack incorporates new wireless link MAC, DLC and wireless control sublayers, together with appropriate mobility extensions to the existing ATM network control layer. Wireless control and ATM signaling capabilities required for mobility support are discussed, and preliminary solutions are given for selected major functions. Potential extensions to standard Q.2931 ATM signaling are proposed to support handoff and service parameter/QoS renegotiation required for mobility. An associated wireless control protocol for supporting terminal migration, resource allocation, and handoff is discussed. Preliminary experimental results are given which validate the proposed handoff control protocol on an ATM network testbed.     

UMB网络架构

超移动觅带（UMB）无线接入技术能以非常高的速率实现IP分组的有效无线传送,同时,即使在小区边缘,也可提供无缝移动和最佳的服务质量（QoS）,而不会降低频率再用。UMB系统利用高度创新的扁平化网络架构,简化了核心网和网络接口,从而易于实现网络扩展。UMB架构的一个主要原则是无缝移动。网络架构的设计是关键所在,有利于实现在UMB网络内和不同技术间的无缝切换。革新性的概念可实现基站间的快速交换,同时最大限度地减少开销和提供简化的网络接口。新的隧道机制提供在数据一链路层（层2）和IP层（层3）的信令交换,实现了跨基站的快速移动。本文探讨了UMB网络架构的主要特性,并对不同架构设计选择进行了深入分析。     

Broadband-Facilitated Inter-WLAN Mobility Architecture

The existing WLAN architecture does not have the capabilities to leverage the wired and wireless broadband-accessed network control for the Inter-WLAN mobility. This paper presents a broadband-facilitated inter-WLAN mobility system architecture including its realization with the wired and wireless broadband-accessed network control for the WLAN mobility management. The proposed broadband-based inter-WLAN mobility management concept has changed the notion of the traditional WLAN mobility. Secondly, an implementation of the distribution system with broadband-accessed central network control for the IEEE 802.11 inter-WLAN mobility along with its management protocol is presented. In addition, this paper provides the modification to the enhanced IAPP protocol signaling messaging required for the broadband-facilitated WLAN mobility management. Finally, simulation experimental results for the proposed inter-WLAN communications architecture’s performance vs. WLAN mobility management performance employing standard and optimized MIP are presented. We believe that the proposed architecture would greatly enhance the Inter-WLAN IP mobility performance. This paper serves as a foundation work for future research in inter-WLAN mobility management using broadband, wired and wireless that integrates high-speed wide area network and WLANs.     

A novel media independent handover‐based approach for vertical handover over heterogeneous wireless networks

The key purpose for seamless mobility and service continuity between heterogeneous wireless networks is the handover. Vertical handover management is one of key challenges in such environment. To deal with some of these challenges, an IEEE 802.21 media independent handover (MIH) framework has been standardized. The main purpose of this standard is to offer a general interface for the handover by abstracting the link layer intelligence to higher layers. However, there still exist a number of limitations in MIH architecture. In this paper, a new architecture of improved MIH is presented to perform vertical handover between wireless heterogeneous networks. We focused on interworking architecture between wireless local area network and long term evolution advanced network with the use of MIH signaling to define an efficient vertical handover. A performance analysis model for the proposed MIH‐based vertical handover is derived. Analysis results show that the proposed method can be easily deployed in present multimedia service networks. Copyright © 2013 John Wiley & Sons, Ltd.     

A Parallel Architecture for Network Control and Mobility Tracking in Wireless Systems

In a wireless system the network logically rearranges itself rapidly whenever terminals move from cell to cell. This ability to adapt itself to changing locations of its terminals adds a new layer of complexity to wireless control software. With ever increasing demand for more capacity and the addition of new service features, many limitations and bottlenecks in the underlying network infrastructure are uncovered. While distributed architectures provide a method for increasing processing capacity, they also introduce concerns regarding reliability, communication latency and cost. In this paper we have attempted to combine the significant characteristics of both fixed and distributed architectures in a single system. Specifically, we present the design of a wireless hub processor, based on a communications oriented active memory technology, and illustrate how the procedures for mobility management, resource management and call processing map on to such a parallel architecture. A key attribute of the architecture is that it scales in processing capacity and size, while maintaining a common locus of control for administration, maintenance and reliability. Finally, we present an example of a navigation application to validate the architecture. This example shows how a roving computer or PDA connected to a global positioning system and having a wireless communication link can deal with a low bandwidth link to a server. The server provides user-tailored map data. An active memory architecture not only provides the server with a scalable architecture but also aids the client.     

Assignment strategies for mobile data users in hierarchical overlay networks: performance of optimal and adaptive strategies

Hierarchical wireless overlay networks have been proposed as an attractive alternative and extension of cellular network architectures to provide the necessary cell capacities to effectively support next-generation wireless data applications. In addition, they allow for flexible mobility management strategies and quality-of-service differentiation. One of the crucial problems in hierarchical overlay networks is the assignment of wireless data users to the different layers of the overlay architecture. In this paper, we present a framework and several analytical results pertaining to the performance of two assignment strategies based on the user's velocity and the amount of data to be transmitted. The main contribution is to prove that the minimum average number of users in the system, as well as the minimum expected system load for an incoming user, are the same under both assignment strategies. We provide explicit analytical expressions as well as unique characterizations of the optimal thresholds on the velocity and amount of data to be transmitted. These results are very general and hold for any distribution of user profiles and any call arrival rates. We also show that intelligent assignment strategies yield significant gains over strategies that are oblivious to the user profiles. Adaptive and on-line strategies are derived that do not require any a priori knowledge of the user population and the network parameters. Extensive simulations are conducted to support the theoretical results presented and conclude that the on-line strategies achieve near-optimal performance when compared with off-line strategies.     

An Intra-domain Mobility Handling Scheme Across All-IP Wireless Networks

The rapid growth of wireless network technology such as HSDPA and WiMAX, has lead to greater demand for access to Internet via mobile hosts. Supporting mobile connection with fast and smooth roaming across heterogeneous wireless technologies has been an important challenge over past years. In this paper, a novel multilayer scheme for QoS-aware intra-domain mobility management is proposed. The mobility support capability is embedded in key components for the domain access network, namely, the Paging Access Routers and the Mobility-support Anchor Servers (MASs). The MASs are organized in three layers; starting from the top layer Superior-MASs, Middle-MASs and Inferior-MASs, respectively. The proposed scheme identified mobility support functionality, includes intra-domain anchor specification, route optimization algorithm, intra/inter-anchor mobility support, paging and authentication management. Simulation results of the proposed scheme show fair performance especially in the presence of QoS sensitive services.     

A software support infrastructure for wireless access routers

Routers are expected to play an important role in the Internet protocol-based wireless data network. Although a substantial number of adaptive and intercell coordination techniques have been proposed to improve wireless network performance under dynamic wireless channel conditions and host mobility, a system support framework is still missing. In this paper, we describe DIRAC, a software-based router system that is designed for wireless networks to facilitate the implementation and evaluation of various channel-adaptive and mobility-aware protocols. DIRAC adopts a distributed architecture that is composed of two parts: a router core (RC) shared by the wireless subnets, and a router agent (RA) at each access point/base station. RAs expose wireless link-layer information to the RC and enforce the control commands issued by the RC. This approach allows the router to make adaptive decisions based on link-layer information feedback on both data and control planes. It also permits the router to enforce its policies (e.g., policing) more effectively through underlying link-layer mechanisms. It further enables interaccess-point coordination at the RC. As showcases, we implement under DIRAC the prototypes of three wireless network services: link-layer assisted fast handover, channel-adaptive scheduling, and link-layer enforced policing. Our implementation and experiments show that our distributed wireless router provides a flexible framework, which enables advanced network-layer wireless services that are adaptive to channel conditions and host mobility.     

无线ATM通信网的关键技术与研究现状

本文介绍支持多媒体业务的无线ＡＴＭ通信网的关键技术，如协议分层模型与网络结构、物理层技术、多址访问控制协议、数据链路控制协议和网络管理与控制技术等，并结合国内外的研究现状进行了论述。     

Efficient resource allocation for China's 3G/4G wireless networks

The all-IP DiffServ model is expected to be the most promising architecture for QoS provisioning in China's next-generation wireless networks, due to its scalability, convenience for mobility support, and capability of interworking heterogeneous radio access networks. This article focuses on efficient resource allocation in a wireless DiffServ architecture. Resource utilization efficiency is particularly important for China's wireless networks as the mobile user density in China is and will continue to be much higher than that in other countries. More specifically, we propose a novel buffer sharing scheme to provide assured service for real-time layer-coded multimedia traffic, which can guarantee the specific packet loss requirement of each layer with UDP as the transport layer protocol. An adaptive optimal buffer configuration can be applied to achieve maximum resource utilization over the time-varying channel. Assured service is also provided to TCP data traffic for guaranteed throughput, where the cross-layer coupling between the TCP layer and link layer is exploited to efficiently utilize the wireless resources.     

Mobility support across hybrid IP-based wireless environment: review of concepts, solutions, and related issues

The 4G or Beyond 3G wireless networks is consist of IP-based heterogeneous access networks from 3G cellular, WiFi, WiMAX to other emerging access technologies such as mesh networks. The key objective of designing the next generation wireless networks is to support of mobile subscribers. To support the mobile host in the hybrid wireless access technologies, many solutions based on network protocol stack have been proposed in the literature. In this article, after review of mobility concepts, a special attention is given to some of the mobility management methods as well as handover techniques across various wireless access networks. We have also compared the major mobility protocols in each layer for their features. Finally, some of the open issues that needed to be addressed in mobility management protocol in the next generation wireless networks are outlined.     

A Cross-Layer (Layer 2 + 3) Handoff Management Protocol for Next-Generation Wireless Systems

Next-generation wireless systems (NGWS) integrate different wireless networks, each of which is optimized for some specific services and coverage area to provide ubiquitous communications to the mobile users. It is an important and challenging issue to support seamless handoff management in this integrated architecture. The existing handoff management protocols are not sufficient to guarantee handoff support that is transparent to the applications in NGWS. In this work, a cross-layer (Layer 2 + 3) handoff management protocol, CHMP, is developed to support seamless intra and intersystem handoff management in NGWS. Cross-layer handoff management protocol uses mobile's speed and handoff signaling delay information to enhance the handoff performance of Mobile IP that is proposed to support mobility management in wireless IP networks. First, the handoff performance of Mobile IP is analyzed with respect to its sensitivity to the link layer (Layer 2) and network layer (Layer 3) parameters. Then, a cross-layer handoff management architecture is developed using the insights learnt from the analysis. Based on this architecture, the detailed design of CHMP is carried out. Finally, extensive simulation experiments are carried out to evaluate the performance of CHMP. The theoretical analysis and simulation results show that CHMP significantly enhances the performance of both intra and intersystem handoffs.     

Supporting dependable group‐oriented mobile transactions: redundancy‐based architecture and performance

Several of the emerging mobile commerce services, such as mobile auctions, mobile financial services, and multi‐party interactive games, will require support for dependable transactions. This is a difficult challenge because of both intermittent connectivity and potential failures in wireless infrastructure. In this paper, we present a multi‐network access‐based wireless architecture and related protocols to support dependable transactions. The key idea is to allow group users to utilize access to one or more wireless networks to complete different steps of a transaction. This allows for transactions to be completed even under time‐ and location‐dependent connectivity problems and network failures. The performance results show that access to multiple wireless networks leads to very high transaction completion probability even when individual wireless networks do not offer continuous and/or highly available access. The transaction completion probability is found to be dependent on the group size and number of steps in a transaction, and the same level of dependable performance for transactions can be achieved by increasing the number of wireless networks or improved access to individual networks. The overhead for multi‐network access can be further reduced by creating preferred wireless networks and by reducing the number of critical users in different transaction stages. Copyright © 2006 John Wiley & Sons, Ltd.     

Seamless SIP-based mobility for multimedia applications

Application-level protocol abstraction is required to support seamless mobility in next-generation heterogeneous wireless networks. Session initiation protocol (SIP) provides the required abstraction for mobility support for multimedia applications in such networks. However, the handoff procedure with SIP suffers from undesirable delay and hence packet loss in some cases, which is detrimental to applications like voice over IP (VoIP) or streaming video that demand stringent quality of service (QoS) requirements. In this article we present a SIP-based architecture that supports soft handoff for IP-centric wireless networks. Soft handoff ensures that there is no packet loss and that the end-to-end delay jitter is kept under control.     

Mobility support in wireless Internet

The tremendous advancement and popularity of wireless access technologies necessitates the convergence of multimedia (audio, video, and text) services on a unified global (seamless) network infrastructure. Circuit-switched proprietary telecommunication networks are evolving toward more cost-effective and uniform packet-switched networks such as those based on IP. However, one of the key challenges for the deployment of such wireless Internet infrastructure is to efficiently manage user mobility. To provide seamless services to mobile users, several protocols have been proposed over the years targeting different layers in the network protocol stack. In this article we present a cross-layer perspective on the mobility protocols by identifying the key features of their design principles and performance issues. An analysis of the signaling overhead and handoff delay for some representative protocols in each layer is also presented. Our conclusion is that although the application layer protocol is worse than the protocols operating in the lower layers, in terms of handoff delay and signaling overhead, it is better suited as a potential mobility solution for the next-generation heterogeneous networks, if we consider such factors as protocol stack modification, infrastructure change, and inherent operational complexity.     

PCS mobility support over fixed ATM networks

As broadband multimedia services and wireless services become popular, there is growing interest in the industry to support ATM over a wireless link, and wireless access to fixed ATM networks. We focus on the internetworking of PCS and ATM networks, in which the air interface remains one of the PCS standards and the backbone is an ATM network with mobility support. It is desirable to minimize the impact of the internetworking and mobility support on the existing/emerging PCS and ATM specifications. A network architecture, a protocol reference model, and signaling protocols for PCS mobility support over fixed ATM networks are described. They are compared against other implementation alternatives and the trade-offs are discussed. Some performance results of the proposed architecture are also presented     

A mobility toolbox architecture for all-IP networks: an ambient networks approach [architectures and protocols for mobility management in all-IP mobile networks]

The future Internet will need to cater to an increasing number of mobile devices and mobile networks, roaming across different access networks and trust domains. In addition, various limitations imposed by the end user, service provider, or network operator agreements and preferences will need to be considered. A plethora of mobility management protocols have been proposed to handle different and mostly limited sets of these mobility requirements. In this article we make the case for coexistence of mobility protocols in order to support the large range of mobility scenarios possible in future all-IP networks. This coexistence takes the form of a mobility toolbox that enables mobility handling mechanisms to be selected according to the context. We then present a design for the mobility toolbox as a component of the ambient networks architecture, including a simplified mobility tool interface toward protocol modules, and show how it meets the requirements of future all-IP networks. We further demonstrate the feasibility and performance gains of the mobility toolbox architecture with a prototype implementation based on network mobility.     

Seamless IP mobility support for flat architecture mobile WiMAX networks - [WiMAX update]

The growing demand for wireless Internet services is accelerating the evolution of wireless networks toward all-IP architecture, and the mobile WiMAX network is a prominent example. Although currently deployed mobile WiMAX networks use hierarchical architecture, flat architecture is feasible and specified as a design alternative in the mobile WiMAX standard. In flat architecture the functionalities of the ASN-GW and BS are consolidated into a single element. In this article we first discuss the benefits and challenges of flat architecture mobile WiMAX networks. We then present a scheme to deal with the seamless mobility issue, which is one of the key challenges of the flat architecture. The proposed scheme combines two standard IP-mobility protocols, Proxy Mobile IP and Fast Mobile IP, and customizes them for IEEE 802.16e-based mobile WiMAX networks. This provides interoperability with existing mobile WiMAX networks. We demonstrate the viability of the proposed scheme through simulations using NS-2.