Wireless Biomedical Home Security Network – architecture and modelling Rudolf Volner, PhD. Department of Air Transport, Faculty of Transportation Sciences Czech Technical University in Prague, Horská 3, 128 03 Prague 2 E-Mail:
[email protected] ABSTRACT The term security network intelligence is widely used in the field of communication security network. A number of new and potentially concepts and products based on the concept of security network intelligence have been introduced, including smart flows, intelligent routing, and intelligent web switching. Many intelligent systems focus on a specific security service, function, or device, and do not provide true end-to-end service network intelligence. True security network intelligence requires more than a set of disconnected elements, it requires an interconnecting and functionally coupled architecture that enables the various functional levels to interact and communicate with each other. This work presents a frame-structure, referred to as BioMedical Home Security System (BHMS), to serve as a wireless network architecture. The widespread BMHS networks are attractive infrastructures for next generation wireless networks. Providing interactive broadband services over BMHS networks is a major trend in communication and ATM (Asynchronous Transfer Mode) networks with broadband communication features well fitted to be the backbone of BMHS networks. Based on the proposed network architecture, this work addresses and investigates the problems of call setup and handoff handling. When designing and configuring an ATM / based broadband BMHS (BBMHS), it remains difficult to guarantee the quality of service (QoS) for different service classes, while still allowing enough statistical sharing of bandwidth so that the network is efficiently utilized. These two goals are often conflicting. Guaranteeing QoS requires traffic isolation, as well as allocation of enough network resources (e.g. buffer space and bandwidth) to each call. 1.
INTRODUCTION
The study of security network intelligence is an extremely active area in the field of communications. Thanks to the latest advances in data communications – especially in the services sector and in the communications software, photonics, and programmable technologies areas – service providers are spending millions of dollars a year on an increasingly intelligent communication infrastructure and
Poušek Lubomír Institute for BioMedical Engineering Czech Technical University in Prague, Zikova 4, 166 36 Prague 6 E-Mail:
[email protected] applications. Research in the areas of learning automata, intelligent agents technologies, intelligent data-mining, knowledge discovery, data-driven task sequencing, intelligent databases, wire-speed real-time databases, virtual modelling, and sophisticated communication network modelling has provided insights into intelligent computing processes. Significant progress has been made in rule-based reasoning, planning, and problem solving. Future generation networking will be characterized by the need to adapt to the demands of agile networking, which include rapid response to changing customer requirements, automated design and engineering, lowercost services, transparent distributed networking, resource allocation on demand, real-time planning and scheduling, increased quality, reduced tolerance for error, and in-process measurement and feedback. Future networking systems will require automated intelligent networking features that apply intelligence to the domain of networking in such a way as to make possible the realization of a full range of agile and adaptable networks. Cable operators will have to face the commercial and operational strategy for: • Building out or upgrading to bi-directional (two way) networks, • Offering voice telephony to residential and business consumers, • Offering multi-channel digital television, • Video-on-demand, • Home shopping, • Home banking, • Residential and business telephony, • High-speed Internet, • Home security. The purpose of distributing the central information server function locally is to reduce the network communications costs by allowing subscribers to access videos through their local information servers. Thus, the distributed interactive information system architecture design needs to be closely aligned to the subscriber access pattern and the marketing strategy. For example, if the system places the most frequently viewed „hot“
information’s as close to subscribers as possible, it is expected that the network communication costs associated with these hot information accesses can be significantly reduced. In this system, an information archive is still needed in case the local information server cannot provide information’s requested by users. Note that each local information server may be a mini - central information server, and its information contents may be downloaded off-line from the central information server and updated periodically. This concept is similar to today’s library but will be served by other local libraries if the serving local library cannot provide the service. The distributed interactive information system can be structured in a hierarchical way for system scalability and evolution – Figure 1, Figure 2. It can start from an initial two level system with a central information server and several local information servers to a system with as many levels of the hierarchy as needed. The number of levels needed depends on the network size, network costs, and network performance requirements. Wireless personal communication services and interactive broadband services have rapidly grown to a significant portion of the world communication market. Extending multimedia services to portable terminals is an emerging need and motivates the integration of wireless and broadband technologies. Several studies have attempted to integrate wireless and ATM network. However, the large transmission speed difference between wireless and ATM networks raises enormous barriers to integration. From the perspective of cost-effectiveness, the already existing BMHS networks are ideal platforms for wireless networks, especially for microcellular op pico-cellular systems with a small cell radius. Figure 3 to provide broadband services to mobile terminals. Since ATM networks are now regarded as a universal base technology for broadband networks and as industry becomes increasingly interest in interactive broadband services to homes, ATM appears a good infrastructure for BMHS/ATM networks. Hence, the proposed two-tier wireless BMHS/ATM network first connects the wireless base stations via BMHS networks and then ATM serves as the backbone of the BMHS networks. The connection-oriented feature of ATM networks differs completely from the shared-medium access methods applied in LAN. In ATM networks, no data can be sent until a virtual channel connection (VCC) is established. In wireless communication systems, since the received signal power change frequently due noise, making a decision to handoff into correct base station (BS) at a right time is a difficult and important issue. Intelligent security and communication networks Intelligent security and communication networks must at least be able to understand the security and communication environment, to make decisions, and to use and manage network resources efficiently. More sophisticated levels of security network intelligence include the ability to recognize user, application, service provider, and infrastructure needs, as well as expected and unexpected events, the ability to present knowledge in a world model, and the ability to reason about and plan for the future.
For the purposes on this paper, CSNI is defined as the ability of a network system to act appropriately in a changing environment. An appropriate action is one that increases the optimal and efficient use of network resources in delivering high-quality services, success is the achievement of behavioral sub-goals that support the service provider’s overall goals. Both the criteria for success and the service provider’s overall goals are defined external to the intelligent security network system. Typically, they are defined by the service provider’s business objectives and are implemented by network designers, programmers, and operators. CSNI is the integration of knowledge and feedback into an input and output-based, interactive, goal-directed, security, networked system that can plan and generate effective, purposeful action directed toward achieving goals. Network intelligence will evolve through growth in computational power and through the accumulation of knowledge about the types of input data needed for making decisions concerning expected response, and about the algorithmic processing required in a complex and changing communications environment. Increasingly sophisticated network intelligence makes possible look-ahead planning, management before responding and reasoning about the probable results of alternative actions. These intelligent network capabilities can provide service providers with competitive and operational advantages over traditional networks. 2. THE BMHS/ATM NETWORK ARCHITECTURE The partitioning of core and edge networks In the traditional digital BMHS approach, all video channels are carried to the end unit box (EUB) or set-top box (STB). As the EUB, channel selection is done by tuning to the respective 6 or 8 MHz channel and selecting the proper MPEG video stream. This architecture is relatively simple from a channel handling point of view because there is no sophisticated switching and traffic engineering involved. The primary function of the edge networks is to provide broadband access to the user through the UNI and to perform cell switching in the local area. The core network functions as the backbone network carrying concentrated traffic between edge networks. The interface between the core and edge network is provided by special edge nodes (gateways). Note that the core and edge networks are still part of a unified ATM network, and should be able to cooperate in terms of bandwidth management, congestion control, and other administration issues through network-network interfaces [2], [3], [5], [9].. The VP assignment policy Currently a number of VP layout and assignment schemes have been proposed [8], which differ in the following ways: • The connectivity of the VP network, that is, whether it is fully meshed or sparsely connected, such as in a star or ring topology,
• How to map the various services to the VPs. One extreme is to use the same VP for all service classes, thus fewer VPs are needed. However, the task of guaranteeing QoS for all service classes in the VP could be difficult. The opposite is to have a separate VP for each service class, or even for each different QoS requirement within the same service class. Although QoS control is easier in this scheme, the total number of VPs needed can be very large. We propose a fully meshed scheme in which there should be at least two VPs assigned between each edge-node-pair (denoted as an origin-destination, or O-D, pair), one for VBR and CBR service and the other for ABR and UBR service. Other VPs may also exist for alternative routing or other management considerations. The VP assignment policy described above is based on the following considerations: • In the fully meshed VP network, pre-assigned VPs exist between all edge networks, and the core nodes can easily be implemented by ATM cross-connectors. No complicated VC level operations such as add/drop or rerouting are necessary. Meanwhile, even if the number of edge networks grows, the VP network can still scale well given the local VPI management scheme discussed in the last section, • The mapping of service classes to VPs should be able to achieve a good balance between QoS achievement and complexity. Thus, we need to carefully inspect the nature of service classes before determining how to map them into VPs. Real-time VBR (a non-real-time VBR connection can be viewed as a real-time VBR with a large cell delay variation tolerance – CDVT – parameter, therefore, non-real-time VBR VCs can be integrated on VBR/CBR VPs) and CBR connections have similar performance parameters in terms of delay and CLR. On the other hand, ABR sources are expected to adapt their rates according to network states and do not require stringent delay performance. Separating ABR traffic from the VBR/CBR VP ensures that ABR rate changes do not affect the performance of CBR and VBR service classes. The nature of UBR services indicates that no network resources should be allocated to UBR connections, consequently, allocating separate VPs to UBR connections is unnecessary. However, the network must provide the necessary isolation (described in the next section) between UBR and other service classes so that the traffic from UBR sources does not affect the performance of other users. Practically, once enough isolation is provided, UBR connections may share the same VP with any other service classes. We choose to integrate UBR with ABR on the same VP because of the similar “best-effort” nature of the two service classes. 3.
THE WIRELESS BMHS/ATM ARCHITECTURE
For a wireless network, the serving area is partitioned into a number of basic service areas designated as cells. Each cell is served by a base station – centre BMHS, which exchanges radio signals with mobile terminals – home control centers. Mobility is central to wireless networks. To provide mobility, tracking mobile terminal locations becomes an important and
primary function of wireless network and hence some databases are introduced to support such a capability. In wireless BMHS/ATM networks, each BMHS network covers a large geographical area and incorporates a number of base stations. The areas served by a set of base stations, which are interconnected via the same BMHS network are typically referred to as a wireless community. A set of wireless communities, connected via the same ATM switch, forms a wireless cluster manager – WCM – to manage the base stations and mobile terminals in its cluster. The wireless cluster manager is responsible for database and connection management for the mobile terminals in its cluster. The databases of the WCM record subscriber location information, authentication information and other information. Since the investigation focuses mainly on mobility management, it overlooks authentication and other functions. Meanwhile, the location database of wireless cluster manager is broken into two parts: • one for the mobile terminals which are permanently registered in the community, the home community – home part, • the other for the mobile terminals which are visiting the community – visiting part. The WCM is referred to herein as the home WCM of those mobile terminals in its home part. The WCM must monitor the location of the mobile terminals in its home part. 4.
WIRELESS SIGNALING PROTOCOL
Recall that an mobile VCC is established for both intraor inter-community mobile connections. Furthermore, to provide seamless handoff, we maintain an individual mobile VCC for each mobile connection instead of a virtual connection for each wireless LAN or a pair of base stations. Routing databases: • base station registration database, • base station routing database, • mobile supported headend routing database, • ATM switch routing database. Mobile connection setup procedure: • call-request message, • location message, • setup message, • connect – reject – message, • connect-ack message, • call-reply message. The mobile connection setup procedure is triggered when an mobile terminal wants to communicate with other end-points. The necessitated processes are classified into two cases: • case intra-community connection, • case inter-community connection. 5. MODELS OF MOBILITY
Mobility models describe a mobile unit’s movement through a geographical area. A number of systematic and ad hoc models have appeared in the literature, but they do net reflect realistic actual movement patterns in many respects. Nor, being idealizations for specific purposes, are they intended to describe adequately the range of subscriber behaviours that will appear in a mobile multimedia network covering a large geographical area. Operators have access to multiple gigabytes of information concerning actual movement of their subscribers and roaming visitors. Although this can be reduced drastically by statistical analysis, the progressive loss of detail gradually makes the information less useful for the desired objectives. It was decided therefore to look for physical analogies that could mimic the mobility of users at an arbitrary range of granularity in the dimensions of population, direction and distance, speed and time. The mobile VCE (The Virtual centre of Excellence in Mobile and Personal Communications) model consists of a series of poles - places where mobile users gather, such as a city centre, a shopping mall or a road (hence the need to include direction). Movement between poles is defined by four properties, which between them determine the spatial and temporal behaviours of the users> • gravity, reflecting the attraction to a pole, • elasticity, reflecting the reaction of restoring equilibrium after changes of attraction, • entropy, modeling the disorder at poles and in the flows between them, • viscosity, representing the spatial spreading variations of the flow populations. The model is a network of poles through which circulates a population of mobiles, whose velocity is determined by the configuration of the above four elements. A mobile can be seen either as an individual or as a mass. Every mobile belongs to a specified mobility class, of which there are four: • business, • leisure, • shopping, • residential. As shown in Figure 4, the model can be decomposed into three distinct sub-models: • the physical sub-model defines the topology and the quantitative spatial distribution of the mobiles, • the gravity sub-model controls the temporal evolution of the attraction of all the poes, • the fluid sub-model fixes the laws of circulation of each mobile between the poles. 6. CHARACTERIZATION OF SERVICES, TRAFFIC SOURCES AND SYSTEM TELETRAFFIC Traditional traffic modeling of data sources assumed that the inter-arrival times of traffic packets were basically exponential in distribution and independent of one another, which means that the process is memory-less. However, recent studies of the behaviour of individual multimedia sources and system-level activity show that traffic traces are distributed in ways more complex than this.
Our analysis has aimed at improving the best-fitting model for a given traffic scenario when the underlying flow keeps changing over time and space. To be confident that the results are useful a model was sought that: • was as simple as possible in a computational sense without compromising accuracy, • had a physical explanation in the network context, • can be related to real measurements for verification purposes by the operators. The investigation focused on extensions that could retain tractability, in two steps as described below: • statistical multiplexing, • parameterization. Traffic generation – if the traffic is memory-less, generation of traffic to support the simulations can be achieved simply by a negative exponentially distributed process to specify packet inter-arrival time. However, modeling self-similar traffic is much more complex [5], [6], [12], [13], [18]. 7. COMBINING TRAFFIC AND MOBILITY From the elements presented in the preceding section, the final stage of the programme specified and implemented a set of tools to provide a platform to take the work forward into the next phase of the research. These tools can be grouped into two areas: • system modeling tools, which embody the mobility and tele-traffic components within a set of simulation libraries, • traffic generation libraries, to create data sets with time and volume distributions that are representative of typical applications. The system is not limited to the in-business applications originally imagined by the developers – Figure 5. 8. CONCLUSION In this paper, we have proposed a wireless BMHS/ATM network for supporting multimedia communication to mobile terminals. Here the network is partitioned into core and edge networks. The advantage of this portioning has been discussed. The network bandwidth is allocated in such a way that each VP is semipermanently allocated a certain amount of using existing optimization techniques. Cell scheduling and queuing implementations were discussed. We conclude, that based on the proposed bandwidth management framework, all ATM service classes can be served with reasonable QoS guarantees, the CAC procedures easily implemented, and potential rate-based ABR congestion control easily incorporated. The work described in this paper has been strongly directed by the mobile communication industry’s real concerns in realizing business opportunities in the next generation of mobile multimedia communication networks. The models that were implemented provide the opportunity for new insights into the behaviour of
mobile multimedia communication systems, including the mobility of subscribers, the types of traffic they generate and the expected properties of that traffic individually and in aggregate. REFERENCES [1] Volner, R., : CATV – Interactive Security and Communication System, proceedings the institute of electrical and electronics engineers, 34th Annual 2000 International Carnahan Conference on Security Technology, October 2000 Ottawa, Canada, pp. 124-136 , IEEE Catalog Number 00CH37083, ISBN 0-7803-5965-8, [2] Volner, R., : Home security system and CATV, 35th Annual 2001 International Carnahan Conference on Security Technology, October 2001 London, England, pp. 293 – 306 IEEE Catalog Number 01CH37186 , ISBN 0-7803-6636-0, [3] Volner, R., : CATV Architecture for Security, 36th Annual 2002 International Carnahan Conference on Security Technology, October 2002, Atlantic City, New Jersey, USA, pp. 209 – 215, IEEE Catalog Number 02CH37348 , ISBN 07803-7436-3, [4] Volner, R., Poušek, L. : Inteligence Security Home Network, 37th Annual 2003 International Carnahan Conference on Security Technology, October 2003 Taipei, Taiwan, pp. 30 – 37, IEEE Catalog Number 03CH37458 , ISBN 0-7803-7882-2, [5] Volner, R., Boreš, P., Tichá, D.: CATV - architecture and simulation network; conference proceedings, The 6th Biennial Conference on Electronics and Microsystems Technology BEC 98, Tallinn, Estonia, October 1998, pp. 211 - 214 [6] Volner, R., : Inteligence CATV – Traffic models, Design and Analysis, International Conference on Computer, Communication and Control Technologies CCCT’03 and The 9th International Conference on Information Systems Analysis and Synthesis ISAS 03, Proceeding volume IV, July 2003, Orlando, Florida, USA, pp. 340 – 345, ISBN980-6560-05-1, CD - ISBN 980-6560-10-8, [7] Klima, M.: Some Remarks On JTC Identification Method For Security Purposes, Proceedings of 32nd Annual 1998 International Carnahan Conference on Security Technology, October 1998, Virginia, USA, pp. 163-168
[8] Klima, M.: Evaluation of JTC Method Robustness in Security Applications, Proceedings of 33rd Annual 1999 International Carnahan Conference on Security Technology, October 1999, Madrid, Spain, pp 233-237, IEEE Catalog Number 99CH36303, ISBN 0-78035247-5, [9] Hottmar, V., Kuba, M.: Microcomputer converter of the telex signal; Komunikácie, - vedecké listy Žilinskej univerzity, (in Slovak) [10] Volner,R. et al.: CATV In Multimedia Transmission Systems, Electronic Horizont, Vol.55, Nov./ Dec. 1995 [11] ATM Forum Technical Committee: Traffic management specification version 4.0, AFTM 0056.000, Apr. 1996 [12] ATM Forum Technical Committee: User-network interface (UNI) specification version 3.1, 1994 [13] Hottmar, V.: TV Set for Interactive Cable Television; SAKT Kongres káblová televízia 1213.11.2002 Bratislava, (in Slovak) [14] Volner, R., Boreš, P., Tichá, D.: CATV and PC = Information Network; proceedings of International Symposium on Signals, Circuits and Systems SCS ‘97, Iasi, Romania, October 1997, pp. 81 - 84 [15] ATM Forum technical committee :Flow controlled connections proposal for ATM traffic management, sept. 1994 [16] Volner, R. : ATM/IP CATV network, Poster Abstract of the 25th International Conference on Information Technology Interfaces, Cavtat, Croatia, june 2003, pp. 57 - 58, ISBN 953- 96769-8-3, [17] Irvine, J., M., Tafazolli, R., Groves, I., S.: Future mobile networks’, Electronics & Communication Engineering Journal, December 2000, pp. 262 – 270 [18] Hottmar V.: Výkonnosť prerušovacieho systému; VŠB Ostrava, FEI ; V.seminár katedry elektroniky a telekomunikačnej techniky 22.11.2002, (in Slovak ) [19] ATM Forum/95-0221R2: Draft PNNI signaling, 1995
Figure 1 - Basic BioMedical CATV System – Metro Subsystem
Figure 5 Mobile awareness service
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Figure 2 The BMHS interactive system can be structured in a hierarchical way for system scalability and evolution
Figure 4 Mobility model into three submodels
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Home Network Figure 3 The wireless BMHS/ATM network architecture
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