Mobile Ubiquitous Service Environment

Zhang Ping，Ji Yang，Feng Zhiyong

（Wireless Technology Innovation institute, Beijing University of

Posts and Telecommunications, Beijing 100876, China）

7 Architecture of MUSE Network

I t is an obvious trend to fulfill an all-IPnetwork layer for the future network,and the standardization organizations are taking efforts to evolve the architectures they developed into all-IPnetworks.However,below the network layer,there are various wireless access networks heterogeneously coexisting without any tendency to be integrated into one access network.Different areas prefer the coverage of different wireless access networks.For example,the Wireless Local Area Network（WLAN）with broad bandwidth is being applied more popularly at hot spots such as cafes and airports;cellular technologies,supporting good mobility,are playing the most important roles in the wide area environment;various short-distance low-power broadband wireless communication technologies（represented by Ultra Wideband,or UWB）are emerging from the personal area environment.It is predictable that,driven by new applications,more access technologies willemerge.Therefore,the future will be an era of diversified access networks without any integrated air interface technology and networking mode.

The diversity is owed to the fact that there is no single wireless technology that can meet all the demands in any environment.For example,a 3G cellular network can let its users enjoy continuous and stable voice service when they move at high speeds（like hundred kilometers per hour）,but cannot support their access to the Internet at ten megabytes per second even in a static condition;UWB technology can fulfill gigabyte-level transmission rate in a several-meter coverage,but cannot provide large-area coverage.Differences in networking modes and transmission technologies assure the places of different wireless access technologies in the future wireless communication field.

The heterogeneous coexistence is a feature of the future system.Therefore,it is necessary to design a new service-provision-oriented architecture to support the harmonious development of heterogeneous technologies.This will help fulfill the convergence of heterogeneous networks.

The cooperation and convergence of networks is also one of the core ideas of Mobile Ubiquitous Service Environment（MUSE）.In MUSE,the communication system can,by the cooperation of heterogeneous sub-networks,support moving at different speeds and seamless connection.Besides,intelligent and ubiquitous terminals and sensor networks can fully exchange messages about circumstances and context such as individual preferences,users'health and moods,and temperature and humidity,supporting the integration of information and physical spaces.

The convergence of heterogeneous subsystems with complex attributes and diversified contents willbe a three-phase process influenced by demands.

In the first phase,separated sub-networks can interconnect and interwork with each other.The fulfillment of the interworking is the main goal in this phase,which involves the service,network control middleware and access layers.

In the second phase,the interworking heterogeneous subsystems form a cooperative network.In this cooperative network,an orderly Integration of separate local capability strengths and resources（i.e.,better optimization of resources）can be achieved.Cooperative service provisioning will show the advantages of the cooperation,which will also be represented by the integration of ubiquitous mobile equipment,computing and physical resources.

In the last phase,the whole influences the parts,that is,the cooperative network will have impact on the characteristics of the subsystems.Meanwhile,the subsystems will also influence the whole network.This mutual interaction makes the cooperative network to step into the stage of evolvable optimization development.The open cooperative system willintroduce more heterogeneous entities into itself.Its successive expansion will lead to a huge and complicated system.Through the cooperation,the system creates a series of new working models such as self-cure,self-management,self-discovery,self-planning,self-adjustment,and self-optimization.With a goal of providing effective service,the evolution will make the network more intelligent.

The customer-oriented MUSE reference model has four main functional elements:user,Terminal Service Environment（TSE）,Network Service Environment（NSE）,and services.

The NSEhas various heterogeneous sub-networks.It functions as a bridge to connect the TSEand services by the cooperation of its sub-networks.In the NSE,the heterogeneous sub-networks are fully integrated to form a self-adjustable,self-organizable and self-manageable cooperative network.The NSEwill make an adaptive network environment according to context and users'preferences provided by the TSE,and it brings users with Always Best Experience（ABE）by efficient and inter-domain resource allocation and seamless service provisioning.It will also interact and integrate with a plenty of typicalself-organizing terminal environments at its edge.Accordingly,the multi-layer united control and mutual support willcreate great space for diversified personalized services.Moreover,the NSEoffers an open platform to encourage the rapid development and deployment of diversified customer-oriented services.

8 Technical Challenges Facing the NSE

It is not easy to implement a fully converged network service environment.

The NSEfaces the following challenges:

（1）Allocation of Frequency Resource

Increasing demands on broadband communications in the future will make frequency resource deficient.However,uneven service distribution in time and space makes it possible to combine frequency reallocation and dynamic allocation with service requirements to fulfill effective use of frequency resource.

（2）Discovery and Selection of Heterogeneous Wireless Networks

Heterogeneous networks belong to different operators/individuals.Therefore,multi-mode terminals are required to distinguish the local environment automatically.As for seamless heterogeneous handover,a network has to be aware of its heterogeneous neighborhood;however,there is no such mechanism.In a heterogeneous network environment,an automatic network discovery mechanism is important because it is impossible for operators to make all topologic configurations for other heterogeneous networks that have spontaneously emerged.

Network selection is also important.The object of ABEactually means selection,and users will finally influence the overall element distribution of the heterogeneous network by network selection.

（3）Cooperative Management and Control of Inter-domain Networks

From users'point of view,seamless communication require networks to cooperate with each other.With regard to network operation,the resource optimization of heterogeneous sub-networks wants new control mechanism to fulfill cooperative management and control of inter-domain networks.The cooperative management and controlis a general concept,including the management of mobility,radio resources and security.Therefore,the MUSEsystem requires the support of a flexible and efficient signaling system.

（4）Software Radio Technology and Network Reconfigurability

Software Radio is an attractive solution to fulfill seamless interworking between heterogeneous networks.Besides,it theoretically contributes to easy technical upgrade and progress.However,this technology has a long way to go before practical application.On the other hand,it is possible for both base stations and terminals to adopt software radio technology.In this case,the entire network is possibly required to be reconfigured.

（5）Resource Cooperation and Optimization between Air Interface Technologies

The coexistence of different wireless communication modes aggravates the rush for frequency resource.The distribution of frequency in space and for services is uneven.Therefore,the cooperative scheduling of frequency resource can optimize the overall network performance.Resource cooperation and optimization also includes traffic balancing,channel selection and handover relationship selection.

（6）Mutual Control of Accounting and Communication Modes

Various communication technologies mean different types of relationships between services and costs,and further mean multiple charging relationships.Customers always select those communication modes with low charges;price becomes a lever for network operation.Due to overlapped deployment of the wireless technologies in space,mutual control of prices and communication modes looks more refined and more compact

（7）Network Self-management and Self-control

Network heterogeneity leads to complexity of network management.Besides,in MUSE,the network,influenced by user mobility,has to handle its cooperation with the so-called instant networks.It is impossible for all these dynamic processes to be manually handled.Therefore,the problem in network control and management is balancing working situations of the networks by self-adjustment and self-management,rather than by manually managing and controlling the networks.

（8）Security and Trust

Inter-domain nodes and networks require establishing secure and trustworthy relationships when they cooperate.Besides,many new situation-aware-based services can possibly become threats to users'privacy.The inter-domain security and trust is based on the negotiable relationship between the domains,and involves allthe layers related to communication control.Moreover,in the heterogeneous environment,mutual adaptation and conversion should be implemented in different security modes.（9）Overall Cooperation for MUSE

Available core networks support neither the management and control of heterogeneous domains,nor the terminal service environment network.Besides,the service support platform fails to support the inter-domain cooperation or task sharing.For access networks,their management of resource,routing and mobility is functionally required to be able to work with the core network.The overall requirements of the MUSEsystem require layering the network,and inter-layer and inter-domain optimization,so as to fulfill highly-effective cooperation in the system.

9 MUSE Network and Key Technologies for Its Fulfillment

9.1 Network Reconfiguration

The reconfiguration technology is based on the heterogeneity feature of the wireless access environment.It enables network and terminals to support multiple access technologies and to be capable of flexible adaptation by combining the programmable,configurable and abstractable hardware environment and module software design.Its goal is to optimize the usage of heterogeneous resources,and to deliver ABEto users.

The theory of network reconfiguration,based on the distributed system theory,aims to study the MUSEenvironment that orients multiple access technologies,multiple terminal capabilities,asking for diversified service requirements.This theory includes the study of the following aspects:

（1）System Reconfiguration

The requirements on what attributes the reconfigured system should have must be clear.The attributes include the granularity,atomicity and integrity of reconfigured components,and the equivalence of similar capabilities of heterogeneous elements.Besides,the MUSEsystem is strongly distributed,mobile and open,and has security requirements.Therefore,its restraints to system reconfiguration have to be studied.It is also necessary to develop network capability detection mechanism and methods.

（2）Rules for Naming Reconfigured Components

Global names will be resolved,and a resource change mechanism for heterogeneous names'space and levels,name analysis and name attributes should be built.

（3）Network-based Reconfiguration Mechanism

The reconfiguration of a terminalcan be initiated either by the terminal or by the network.The intelligence of the terminalgives it the capability to interact with the network,other terminals,or new software of other terminals.It is required to define programs and signaling for interaction between communication entities to implement reconfiguration,and to specify the smallest signaling set to control the reconfiguration program,i.e.,a process of request,control and management.

The study also includes:

·The terminal's discovery of services that support the reconfiguration process,and its analysis of hidden wireless middleware agent technologies;

·Automatically changing and RAT identifying the frequencies of required functions in a dynamic frequency environment;

·Developing the common standardized protocol for the negotiation of vertical handover;

·Making the wireless middleware's requirements and corresponding restraints clear;

·Defining the wireless middleware service for the management of affairs and interactions;

·Finally establishing a complete network reconfiguration mechanism,including triggering,discovery,negotiation,agreement,execution and release.

（4）End-to-end Reconfiguration Framework

The reconfiguration strategy execution framework is defined,and the protocols for signaling exchange and communication between components in the basic reconfiguration process are created.

（5）Reconfiguration for Optimization

Certain election algorithms and scheduling mechanism are used to achieve the goal of ABEand the most efficient resource utilization.

（6）Resource Management of Reconfiguration System

The mechanism for the discovery and recording of resources and the mechanism for accessing consistent global resource status are established.

9.2 Resource Allocation

The MUSEsystem efficiently makes use of heterogeneous network resources by management and control,and implements cooperation between resource allocation functional entities.

9.2.1 RRM Mechanism in MUSE

First,a new Radio Resource Management（RRM）algorithm that makes full use of the reconfiguration and transmission capabilities of heterogeneous networks will be studied on the basis of the available RRM algorithm used in single mobile network environment.This study aims to improve combined frequency utility when users'experience is fully considered.Then,the use of the unified RRM interface supporting the cooperation between RRM functional entities will be researched,and the RRM mechanism for inter-layer cooperation will also be studied.

RRM is a complicated process,but is indispensable in the deployment of 4G networks.RRM plays an important role in effective management of the entire reconfiguration process.RRM offers dynamic management of network resources such as frequencies,and it also dynamically allocates service flows for different access networks in the heterogeneous wireless access system.

Joint Radio Resource Management（JRRM）is defined as a set of network control mechanisms.These mechanisms can support intelligent call session admission control,and distributed processing of services and power,optimizing radio resources and maximizing system capacity.JRRM uses multiple access technologies at the same time,and it requires the support of reconfigurable or multi-mode terminals.

Besides,JRRM defines a Hierarchical Radio Resource Management（HRRM）method,which uses the strength of common core functions of access technologies,and can create a complete protocol stack through its built-in modules.

The available frequency allocation methods are set,and cannot dynamically distribute frequency bands to different access technologies.However,the coexistence and cooperation of heterogeneous technologies makes flexible and dynamic frequency management possible.With intelligent management mechanism,the dynamic frequency allocation enables maximized capacity of,and minimized interference between,access technologies.

In detail,RRM includes:

（1）Dynamic Adaptive RRM Algorithm Based on Reconfiguration Theory

The algorithm can make full use of adaptive encoding,adaptive modulation and adaptive antenna technologies,and it can also cooperatively work with reconfigurable terminals.

（2）Common RRM Algorithm Supporting Heterogeneous Networks

This algorithm can integrate different air interfaces to make full use of radio resources of different heterogeneous networks.It has two strategies:interoperation based on distributed RRM agents,and common RRM algorithm simultaneously applied in heterogeneous networks.

（3）Evaluation Mechanism for RRM Algorithms in Heterogeneous Networks

A brand-new evaluation mechanism is created to comprehensively evaluate the utility of radio resources to obtain the joint radio resource utility ratio.

（4）Interaction of RRM Algorithms with Mobile IPQuality of Service（QoS）Mechanism

This design enables the RRM algorithms in heterogeneous networks to support mobile IPQoSmechanism;it also makes interactive strategies for RRM entities and bandwidth agents.

（5）Verification of RRM Algorithms in MUSE

This includes simulation of the efficiency of RRM algorithms,and the verification of RRM algorithm evaluation mechanism.

9.2.2 QoSMechanism in MUSE

The QoSmechanism in the MUSEsystem includes interoperation of different QoS mechanisms,and QoSbetween heterogeneous access networks.

（1）Common ABE-based Multi-domain QoS

Based on context describing network,terminal and service,a common QoS mechanism between heterogeneous access networks is created by using the strategies such as access control,resource reservation,traffic detection and multi-protocol inter-layer cooperative resource allocation,so as to improve network resource utilization when the ABEis offered and QoSof joint flows is ensured.

（2）Interoperation of Different QoS Mechanisms

Interactive processes between different network resource allocation entities are studied to strategize the cooperative management of bandwidth,time delay and resource cost among heterogeneous networks.

（3）QoSSupport Protocols

In order to support the cooperative resource management mechanism that crosses both heterogeneous networks and multiple protocol layers in MUSE,either the available QoSsupport protocols have to be improved,or a brand-new QoSsupport protocol has to be designed.

（4）Verification of QoSMechanism in MUSE

This includes emulation of QoS mechanism,and complete verification of related protocol processes.

9.3 Cooperative Control Mechanism and Method

Based on the study of seamless connection and controllability of core and access networks,the cooperative control mechanism and method in MUSE enables intelligent,accurate and reliable cooperative control in heterogeneous network environment.It mainly aims at the mobility management in MUSE.

The MUSEsystem is required to support the mobility management mechanism of heterogeneous networks in order to offer common mobility management function including the management of roaming,handover and paging.First,mobility management mechanisms between typical mobile communication networks are created,and then,based on this,the common mobility management mechanism for the heterogeneous network environment is established.In the end,these mechanisms will be verified in MUSE.In detail,these mechanisms are:

（1）ABE-based Handover Mechanism

This mechanism,which makes full use of context describing network,terminal and service,is for handover management.It aims to provide ABE,and also takes the best joint resource utilization into account.It will be designed as a handover algorithm that,comprehensively considering users'experience,current network conditions,current terminal capabilities and current service usage situation,can make the optimal handover time and selection,and resource reservation time and mechanism.

（2）Roaming and Paging Management Mechanisms Based on Heterogeneous Network Descriptive Parameters

The mechanisms make full use of heterogeneous network descriptive parameters to fulfill optimal roaming and paging management,especially the management of paging price and joint paging in inter-network joint paging,and interoperation and reconfigurability of roaming management mechanisms for heterogeneous networks.

（3）Mobility Management Supporting Structured and Ad Hoc Networks

This is a mobility management mechanism that is compatible with handover,roaming and paging between structured and Ad hoc networks.

（4）Security Mechanism for Handover of Heterogeneous Networks This includes unified management mechanism of users in heterogeneous networks,cooperative mechanism for verification on subscribers by different service providers,algorithms and mechanism for subscribers'authentication,and unified security handover management mechanism.

（5）The Study of Mobility Management Protocol

The available mobility management protocols can be improved,or a brand-new mobility management protocol is created,to support mobility management in MUSE.

（6）Verification of Mobility Management Mechanism for Heterogeneous Network Environment in MUSE

This includes simulation of the implementation efficiency of handover algorithms,simulation of signaling price of mobility management,and complete verification of mobility management protocols.