Architectures for IP-based network-assisted mobility management across heterogeneous networks [architectures and protocols for mobility management in all-IP mobile networks]

In this article new architectures for network- assisted management of vertical handovers are proposed, relying on IP-based protocols, aiming at achieving the most relevant intersystem mobility decision with respect to user satisfaction and operator added value. The key design principle used is ease of deployment, with flexible hierarchical handover decision entities allowing the distribution of the decision process across local and global levels. The decision itself relies on a broad set of parameters at the radio, networking, application, user preferences, and operator policies levels. The advantage of the approach is highlighted in the specific cellular/WLAN scenario, and a proof-of-concept testbed has enabled to validate it. Standardization in this area is currently ongoing in 3GPP, IEEE, and IETF.     

Compact wide bandwidth dual-port DRAM architecture suitable for mobile multimedia processors

A DRAM architecture capable of providing dual-port interface is presented. The architecture utilises a novel global bitline scheme to obtain a very wide data bandwidth not possible using traditional DRAM architectures. Furthermore, the area penalty is minimised by using a conventional one-transistor one-capacitor cell coupled with special sensing units that have 84.6% more transistor count. The architecture allows simultaneous read and write access using a conventional two-metal DRAM fabrication process.     

MPEG-4多媒体移动通信系统的一种有效复用结构

介绍了一种基于MPEG－4标准的移动多媒体的两层复用结构。第一层对有相似服务质量（QoS）要求的基本数据流进行打包,形成具有较少QoS要求的数据流;第二层为每个数据流提供相应的防误码措施,形成可在易误码链路进行传输的单一数据流,达到既满足各个基本数据流防误码的要求,又使复用开销最小。     

A time-efficient architecture for multimedia applications

This paper presents an architecture that enforces time requirements and gives minimal end-to-end delays for multimedia applications. The layers and mechanisms allowing the system to fulfill the selected synchronization, i.e., the logical relationships and timed interval semantics, are presented. The proposed approach relies on the use of a formal model based on extended time Petri nets, i.e., the time stream Petri net model (TStreamPN), that allows the user to completely specify the time requirements of a given application. The architecture implements, in the application layer and on top of asynchronous environments, the requested quality of service (perceived by the user) with respect to time. At the transport layer, the use of a partial order transport service improves the reactive response of the communication transfers. Its principles are presented together with a presynchronization sublayer that makes the partial order transport service match the applicative synchronization requirements. Moreover, measurements on the implementation of a videoconference system show that the requirements of the quality of service are fulfilled     

A general architecture in support of interactive, multimedia, location-based mobile applications

The widespread use of cellular telephones and the availability of user-location information are facilitating the development of new personalized, location-based applications. However, as of today, most of these applications are unidirectional and text-based where the user subscribes and the system sends a text message when appropriate. This article describes a modular and general architecture that supports the development of interactive, multimedia, location-based applications, providing an extra level of service to the users. The flexibility of the architecture is demonstrated by presenting the wireless safety security system (Wi-Via) and other potential applications     

Multimedia IP architecture trends in the mobile multimedia consumer device

A dedicated media processor is used in many mobile consumer devices to accelerate video, image, graphics, and display processing. Increased demand for higher pixel resolution, higher quality image and video processing, more graphics performance necessitates dramatically increased signal processing capabilities. To provide the increased performance at acceptable cost and power requires redesign of the traditional architecture. By wisely partitioning algorithms across programmable and fixed-function blocks, the performance goals can be met while still maintaining flexibility for new feature requirements and new standards. For a better than acceptable user experience and playback time, all IPs (display, graphics, video, and imaging) have to be optimized as an “end to end” system. In this paper, an overview of the future trends of multimedia IP processor architectures is provided that describes the implications on system architecture, power, and performance.     

A framework architecture for multimedia information networks

An overview of the INA architecture, which builds on the current advances in broadband communication and distributed computing technologies and specifies an architecture for future information networks that are required to transport multimedia information and to manage multimedia communication, is presented. The key functional separations that have to be met in any INA-consistent network, the major components of an INA-consistent network, and the various levels in the architecture are described. The INA architecture is compared to other networking and distributed-processing architecture     

Ku频段地面移动卫星多媒体传输系统分析

介绍了一种宽带Ku频段地面移动卫星多媒体传输系统。对地面移动卫星通信地球站特点进行了分析。针对3种天线口径进行了卫星链路计算，并对计算结果进行了分析。     

A multicast mechanism for mobile multimedia messaging service

Based on the cell broadcast service architecture, this paper proposes an efficient multicast mechanism for the universal mobile telecommunications system to support multimedia messaging service (MMS). We define a new interface between the serving GPRS support node and the cell broadcast center to track the current locations of the multicast members. Then we describe the location tracking procedures (including attach, detach, and location update) of the multicast members and the multicast message delivery procedure. We use an analytic model to investigate the performance of our approach. This paper indicates that our MMS multicast mechanism outperforms the previous proposed approaches.     

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.     

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.     

A mobility measure for mobile ad hoc networks

A mobility measure for mobile ad hoc networks is proposed that is flexible because one can customize the definition of mobility using a remoteness function. The proposed measure is consistent because it has a linear relationship to the rate at which links are established or broken for a wide range of mobility scenarios, where a scenario consists of the choice of mobility model, the physical dimensions of the network, the number of nodes. This consistency is the strength of the proposed mobility measure because the mobility measure reliably represents the link change rate regardless of network scenarios.     

A new 'constant-amplitude' architecture for MQAM transmission

Constant-amplitude transmitter architectures offer high amplification efficiencies by using one or more nonlinear amplifiers. In this article, we propose one new such architecture, dubbed DbPSK, for efficient MQAM transmission. The proposed architecture decomposes the MQAM constellation into two pseudo-MPSK constellations that are independently amplified, with high efficiency nonlinear amplifiers, then combined to generate the original MQAM signal amplified. We show that the proposed architecture provides interesting performance in terms of power, efficiency and linearity for any MQAM signal transmission and we discuss its implementation aspects. This architecture can be considered as an improvement of the NLA-QAM architecture used in satellite applications.     

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.     

A routing architecture for mobile integrated services networks

A drawback of the conventional Internet routing architecture is that its route computation and packet forwarding mechanisms are poorly integrated with congestion control mechanisms. Any datagram offered to the network is accepted; routers forward packets on a best-effort basis and react to congestion only after the network resources have already been wasted. A number of proposals improve on this to support multimedia applications; a promising example is the Integrated Services Packet Network (ISPN) architecture. However, these proposals are oriented to networks with fairly static topologies and rely on the same conventional Internet routing protocols to operate. This paper presents a routing architecture for mobile integrated services networks in which network nodes (routers) can move constantly while providing end-to-end performance guarantees. In the proposed connectionless routing architecture, packets are individually routed towards their destinations on a hop by hop basis. A packet intended for a given destination is allowed to enter the network if and only if there is at least one path of routers with enough resources to ensure its delivery within a finite time. Once a packet is accepted into the network, it is delivered to its destination, unless resource failures prevent it. Each router reserves resources for each active destination, rather than for each source–destination session, and forwards a received packet along one of multiple loop-free paths towards the destination. The resources and available paths for each destination are updated to adapt to congestion and topology changes. This mechanism could be extended to aggregate dissimilar flows as well. This revised version was published online in June 2006 with corrections to the Cover Date.     

A CDMA network architecture using optimized sectoring

We propose a network architecture for code-division multiple-access (CDMA) cellular systems based on adaptive sector coverage. We show that there is a capacity limit for a CDMA system, which for a soft limit is fairly hard. We also show that for nonhomogeneous traffic, changing the area of coverage for each sector in a sectored-cell can absorb the dynamics of the traffic. For a cell of a fixed radius, divided into n sectors, it is possible to select the angles of coverage of each sector in order to avoid excessive blocking due to temporary nonuniformity of traffic across the cell. This result is based on the fact that for a given set of system parameters (bandwidth, bit rates, E_b/N₀ etc.), a certain amount of area is covered. Hence, the exact shape of the cell/sector is not important. The idea presented is shown to be applicable to overlapping sectors     

A layered protocol architecture for multimedia wireless‐PCS networks

Coupled with the growing interest in the Universal Mobile Telecommunication System (UMTS) as a standard for future mobile communications, the need for a set of functions to effectively support multimedia teleservices in such an environment is also increasing. Starting from the idea that multimedia means the integrated manipulation of different information and hence the independent handling of separate information is not satisfactory, an enhanced protocol architecture for the support of multimedia teleservices in Wireless Personal Communication Systems based on UMTS is proposed. It involves Physical, MAC, Data Link, and Network layers. A Synchronisation Sub-Layer is introduced on the MAC level with the main aim of assuring a rough multimedia inter-stream synchronisation over the air interface, which is a first step prior to a fine end-to-end synchronisation performed by higher layers. Proposed functions, their basic algorithms, their location in the protocol stack, as well as the signalling exchange among modules implementing them, on network and user sides, are described in detail in the paper. The resulting architecture well fits the demanding nature of multimedia services and can be easily interfaced with the wired backbone of the system. This revised version was published online in July 2006 with corrections to the Cover Date.     

A multimedia medical communications system

The problem of communicating the radiologist's findings to the attending physician is introduced, and it is shown why it is essentially a multimedia communication problem. A multimedia communications system that was designed with a focus on database and medical reports organization and architecture is described. A report is presented of some of the key results of an in-house trial linking the Department of Radiological Sciences and the Emergency Department at the Ottawa Civic Hospital, Canada, a 950-bed tertiary-care teaching hospital