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MASA
Mobility And Service Adaptation in Heterogeneous Mobile Networks Mobile Java Service Provisioning Solution

These days we have the ability to bring our desktop on the road and can stay connected in a variety of ways. In addition, our ability to stay in touch is increasing as new networks evolve to meet our needs. In short, we are entering a new aera. We are developing the Masa Network with the goal of providing a total network solution that meets and exceeds the needs of the mobile multimedia future. The rules have changed. Users are on the move! Sophisticated technology is allowing everyday users unprecedented mobility and a bright future that promises more freedom with fewer wires. Not only do users want access to their email, data and media services – they want access wherever they travel, on any device and at the best possible quality. Future networks must be ready for these demands with an end-to-end Quality of Service solution.

MASA is End-to-End Quality of Service. Working within the device and the network, Masa is designed to optimize communications on a variety of devices and computer networks to provide the best quality for the user, end-to-end.

MASA optimizes a Variety of Devices. Each computer system is different and Masa allows users customizable preferences and then automatically tunes device performance to match screen size, memory, processor and more.

MASA handles the Network. Both in the air and on the wire, the choice of networks can be many. Masa works diligently to automatically find, monitor and switch to the best network for the user – all without stopping communication.

MASA adapts to Changing Needs. Of course there can always be trouble in the network and Masa is ready for it. Masa is designed to detect problems and adapt communication to overcome network trouble – keeping the information flowing and the quality high.

The Masa Network Solution
Working within the device and the network, the Masa Network is the end-to-end Quality of Service solution for thefuture. Offering a new level of quality, flexibility and simplicity for the new era of multimedia networking.
 

Our motivation:

The Internet offers challenging new opportunities for the development of communication applications such as video conferencing, multimedia distance learning, virtual reality group chating, and many more. In order to enhance the Internet to be a multimedia communication medium allowing anywhere usage by anybody.

One of the most well known problems is the missing support of reliabe and predictable quality for realtime streaming of audio and video content. Therefore, effective methods for providing  Quality of Service (QoS) are needed. anytime, many technical problems still have to be solved.

Since more and more devices will be mobile, most multimedia applications should also be able to run in mobile environments. Unfortunately, the growing number of different fixed line (e.g. Ethernet, ATM, xDSL, etc.) and wireless (e.g. GSM/GPRS, Wireless LAN, UMTS, etc.) access network technologies in combination with the growing variety of user devices (e.g. mobile phone, PDA, WebPad, Multimedia Workstation, etc.) will lead to a high level of heterogeneity with quickly changing terminal power and link qualities.

In recent years, a number of approaches have been proposed to enhance the Internet with different QoS mechanisms, but most of them concentrate only on certain aspects of the overall QoS problem (e.g. video filtering or resource reservation), certain entities of the transmission path (e.g. terminal) or certain layers of the communication model (e.g. DiffServ, IntServ). In almost all of them, key features, like inter-session relationship, multiparty support, adaptation mechanisms, or load-balancing and fast handover.

Therefore, taking also the mobility-specific needs into account we develop MASA as a comprehensive media centric QoS architecture .

The Goal:

The MASA QoS Framework is designed to fulfill the requirements of a comprehensive integrated end-to-end QoS multimedia management system, allowing for the usage of underlying network layer QoS technologies, and hiding the complexity of QoS and adaptive media management from the applications.
By controlling the complete communication infrastructure MASA is able to support QoS in a way, which can neither be realized within the application nor with the underlying network QoS technologies alone.

The MASA framework has the following main features:

  • MASA represents a comprehensive management system for end-to-end QoS .
  • MASA maps high-level (user) QoS policies into appropriate (network) QoS parameters for the underlying QoS technologies. These mapping functions can be easily modified and extended.
  • A QoS API for MASA end-systems is provided to relieve developers of QoS-enabled mobile applications from QoS/media/mobility-related concerns.

Because of the above properties, the MASA framework serves two purposes: on the one hand by providing a ' middleware product ' for rapid development of mobile applications and on the other hand as a research platform for testing of adaptation and handover strategies or QoS policies in general.

The following aspects are of special importance in our research work:

  • Application Separation
  • Adaptive Multimedia
  • Group Conferencing
  • Using Network Layer QoS Mechanisms
  • Open APIs
  • User Profiles
  • Intuitive User Interfaces
  • Plugable-Components
  • Design Principles
  • Admission Control
  • Charging/Billing/Accounting
  • Fairness
  • Operating System Independence
  • Terminal/User/Session Mobility

The Architecture:

The MASA QoS Architecture consists of a distributed set of autonomous QoS Brokers , which can be placed on the (potentially mobile) end-system, on intermediate network nodes (e.g. router, switches) and on transcoding units (gateways). Each Broker delegates and coordinates different QoS Managers which in turn are responsible for specific tasks, like resource-, network-, media-, policy- and mobility-management.

MASA Architecture


The main task of the End-System QoS Broker is to coordinate, orchestrate and manage local and remote resources for multimedia streaming and service quality. In addition, it maps the user's QoS wishes to appropriate QoS parameters and supports mobility between different access networks (e.g. GSM, Wireless LAN, UMTS, etc.)

Network QoS Brokers can be regarded as centralized QoS management units which support the end-system QoS Brokers and organize the orchestration of all streams in the respective network domain according to the network management policy. The network QoS Broker monitors network resources, decides admission in cooperation with other admission controlling entities (e.g. H.323 gatekeepers) and realizes load balancing and fairness concepts for all participating systems. The actual behaviour of the network QoS Broker depends on the location of the respective network node, e.g. core network router, access network router, media gateway, LAN swich etc.

The Transcoding QoS Broker can be instantiated if heterogeneous clients must be supported in a multi-party conference scenario or if special network characteristics on certain network links have to be supported with mechanisms like adaptive Forward Error Correction (FEC), appropriate transmission protocols (e.g. wireless TCP), etc.
Transcoding QoS Brokers can also realize simple filter mechanisms. In our framework we use filter routers to realize priority filtering based on priority settings within the RTP header. This allows for very fast and fine-grained adaptation schemes which are combined with coarse-grained sender rate adaptation schemes in the end-systems.

Communication between this distributed collection of QoS Brokers is realized via appropriate interfaces. Main communication issues are capability exchange methods, QoS routing mechanisms, admission and authorization requests, and the management of media channels.

 

MASA on End-Systems:

The MASA QoS framework can be regarded as a kind of ' middleware ' between multimedia applications and operating systems. As a major feature, MASA is able to separate the adaptive media management from applications . The media management is controlled by the QoS management which is closely coupled with the integrated mobility management.

MASA End System

MASA presents applications with mechanisms for the processing and transmission of 'high quality' multimedia streams, i.e. adapted to the user's QoS wishes and the available infrastructure. Applications subscribe to the system and use the provided facilities via a respective QoS-API . This API can be used to instantiate multimedia sessions. Within the MASA QoS management, the hierarchical concept of participants, sessions, streams and flows is used.
Each participant can have several media sessions with other participants (at remote machines) at the same time.The sessions consists of an arbitrary number of streams with one or more actual media flows. This allows for the usage of layered coding .

The set-up of a complete chain of media processors, consisting of capture devices, codecs, effect processors, etc., can be controlled via this API. Appropriate graphical user interfaces are provided to present media information (e.g. video panel). Since MASA provides a flexible mechanism to plug-in arbitrary components to capture, process, code, transmit, receive, decode and display any kind of media, the applications are shielded from that low-level complexity. Adaptive and layered coding can be used seamlessly by any application to allow for scaleable media transmission.

With respect to mobility, efficient handoff algorithms are a cost-effective way of enhancing the capacity and QoS of cellular systems. MASA supports mobile devices by integrating mobility management into the framework and using fast QoS re-negotiation and adaptation mechanisms to allow seamless intra- and inter-technology handoffs .

Adaptive media processing is controlled via trading policies . MASA offers appropriate intuitive graphical user interfaces to capture user QoS preferences (policy GUI) allowing the selection of a certain CoS as well as appropriate degradation paths for situations with changing resources or transmission link characteristics. On network nodes, preference-controlled management of QoS capabilities for network administration is also supported.

The MASA QoS Management provides mapping functions between QoS parameters at the various levels (user, application, framework, operating system, network sub-system and network layer), to hide underlying QoS parameters from users and applications and support applications with mechanisms to allow soft and hard QoS negotiations .

Group conferencing is enabled with and without the use of multicast mechanisms. This is particularly challenging for heterogeneous devices with varying capabilities, like resources, media processing mechanisms, etc. Clients are supported with capability exchange mechanisms in order to agree on a certain service quality and to dynamically join and leave ongoing sessions. To support different service levels for group communication audio and video filtering is used on network level (packet-based) as well as on application level (content-based). To support heterogeneous devices with incompatible communication mechanisms,  appropriately placed transcoding units can be used.
These units allow for downloading codecs on demand. The placement and optimization of transcoding and filter units can follow intelligent algorithms to optimize network load and processing requirements. 

The provision of differentiated CoS demands for the introduction of charging and billing mechanisms. The MASA architecture supports control of media quality in relation to a cost-over-quality function which is part of the user's QoS preferences GUI.

The MASA end-system is designed as a 3-level hierarchy consisting of QoS Brokers , Managers and Controllers . With this structure, the QoS Broker can delegate separate tasks for controlling and media processing and therefore provides a clear separation of tasks with different time constraints.

Of equal importance is the provision of flexibility for controlling various non-MASA entities (e.g. a Mobile-IP deamon or special network interface card-drivers etc.). The MASA Controller allows for an eased integration of such entities into the framework. The Managers are used to integrate theses Controllers and to provide a standardized interface for the Broker. This allows for much more scalable and flexible solutions as it would be possible with a monolithic structure.

 
MASA Broker Structure

 

The Policy Manager , e.g. is responsible for the storage and retrieval of QoS preferences within a user profile and for presenting an appropriate policy GUI to the user. The Policy Controller enables the access to a policy database. The Resource Managers are responsible for controlling the available resources (like CPU, memory, etc.) via the respective Resource Controllers . The Intercom Manager is used to allow for inter-Broker communication. Different communication layers (e.g. SIP, H.323, CORBA, etc.) can be within different Intercom Controllers . The Application Manager provides mapping functionality between different categories of applications, like VoD or IP-Telephony and the Broker QoS API.

The Broker regularly requests monitoring information from its Managers. The aggregated monitoring information together with the user's QoS policy is used as input for a Trader mechanism which analysis the current situation and decides for possible adaptation of the current active sessions. On the end-system, the algorithm of the Trader is controlled by a local trading policy which can be easily exchanged, even during runtime. The Broker parses the result and informs the respective Managers about the necessary actions that have to be performed to realize the adaptation. Examples are codec changes within the Media Manager or handoffs within the Mobility Manager.

Since not all Managers have to be used for each Broker type, our design provides scalability. For example, at transcoding/filtering nodes, the Broker does not need Application or Mobility Managers. Through the use of open interfaces between the QoS Brokers and Managers, the system can be easily extended with new Manager/Controller pairs. For example, a Manager/Controller pair for power management would allow for supporting a trading policy like when the battery is low, switch to a codec with low power consumption.

MASA in the Network:

Since MASA is a distributed Architecture, Scalability can be easily assured. In each network domain, the respective business role is supported with a dedicated Broker or Broker set. MASA differentiates betweens Access and Core networks . Access networks offer two main aspects to end-customers: IP - connectivity and framework services. The MASA framework services comprise different classes of Services :

  • General Framework Services (e.g. monitoring, call set-up signalling or mobility support)
  • Application Support Services (e.g. codec downloading or capability analysis)
  • 3rd-Party Services (e.g. VoD or Transcoding)
These services are managed within the Access Broker, who offers the service set to the registered ESBs.
The Access Broker is further responsible for
  • Session Management
  • Flexible Admission Control
  • Mobility Support for Mobile End-Systems
  • Interaction with resource reservation/activation/deactivation mechanisms of the Network Broker
  • Proxy service provision for the ESB
  • 3rd-Party Call Control
  • Service Trading
The Access Broker still has knowledge about single users, their running sessions and streams and tries to aggregate them into bandwidth pipes offered by the Network Brokers.
MASA Network

The Network Broker is used in both access and core networks. The NB has only an aggregated view of the traffic in it's domain, significantly reducing the number of states.

The main tasks are:
  • Offering, providing, and maintaining point-to-point interconnectivity services (pipes) with QoS guarantees to ESBs, ABs and other NBs.
  • Performance and Fault Management of pipes. 
  • Request of inter-domain pipes at other NBs.
  • Aggregation of individual requests.
The NEC Flyer about MASA.

The NEC MASA at a Glance handout.

Christian Kücherer, Quality of Service with Adaptive Video Coding, Diplomarbeit im Studiengang Informatik, 2001, University of Applied Sciences Mannheim.

Hyung-Woo Kim, Design and implementation of an adaptation algorithm for audio streaming applications , Diplomarbeit, June 2001, University Stuttgart.

Philipp Bostan, Adaptive Video Transmission For Heterogeneous Networks, Diplomarbeit , 30. August 2002, University of Applied Sciences Mannheim.

Andreas Schrader (NEC Network Laboratories Europe), Oliver Haase (NEC Network Laboratories Europe), High Quality Multimedia Services on Demand, Proceedings of the IEEE Intern.Conference on Software in Telecommunications and Computer Networks SoftCOM'00, Split, Rijeka, Croatia; Triest, Venice, Italy, Oct. 10-14, 2000

Hannes Hartenstein (NEC Network Laboratories Europe), Andreas Schrader (NEC Network Laboratories Europe), Andreas Kassler (University of Ulm), Michael Krautgärtner (Siemens), Christoph Niedermeier (Siemens), High Quality Mobile Communication, Proceedings of the KIVS'2001 Conference (Kommunikation in Verteilten Systemen), German Informatics Society (GI), February 2001, Hamburg, Germany.

Darren Carlson (NEC Network Laboratories Europe), Hannes Hartenstein (NEC Network Laboratories Europe), Andreas Schrader (NEC Network Laboratories Europe), QoS Orchestration for Mobile Multimedia, Proceedings of ASW'2001, The First Workshop on Applications and Services in the Wireless Networks. Evry, France, July 25-27, 2001.

Christian Kücherer (NEC Network Laboratories Europe), Andreas Kassler (University of Ulm), Andreas Schrader (NEC Network Laboratories Europe), Oliver Haase (Bell Labs), End Device and Network Adaptation of WaveVideo Streams, Proceedings of the SSGRR'2001,  International Conference on Advances in Infrastructure for Electronic Business, Science, and Education on the Internet, L'Aquila, Italy, August 6-12, 2001.

Andreas Kassler (University of Ulm), Christian Kücherer (NEC Network Laboratories Europe), Andreas Schrader (NEC Network Laboratories Europe), Efficient Wavelet Video Filtering, QofIS'2001, 2nd International Workshop on Quality of future Internet Services, Coimbra, Portugal, September 24-26th, 2001.

M. Brunner (NEC Network Laboratories Europe) et.al , Requirements for QoS Signaling Protocols, NSIS working group of the IETF, December 2001.

Darren Carlson (NEC Network Laboratories Europe), Andreas Schrader (NEC Network Laboratories Europe), Seamless Media Adaptation using simultaneous Media Processing Chains, ACM Multimedia 2002 Juan les Pins, France, December 1-6th, 2002.

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Last modified 02-Jun-2005
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