Towards a Single Location-awareness System 

Waseem Besada

Abstract: 
Location-aware computing becomes a research focus for future mobile computing and communications environments. By combining a handled computer, a GPS receiver , and possibly, a radio link, it is quite feasible to construct a computerized device that knows where it and can potentially access databases of local information and collect information for further processing. All that is needed is some appropriate software. The intension of this paper is to analyze the impact of location aware traffic in tomorrow networks functionality and infrastructure when small mobile computers will become the preferred computer format. New challenges are addressed and the requirements for and possible architecture of such a system is discussed.

1. Introduction
The integration of hand-held computing with wireless communications and positioning technologies has enormous potential in many fields: location aware mobile devices that permit the navigation of both a physical space and related information space at the same time represent a new interaction paradigm. Also, the users location should be useful for both information retrieval and information recording.
In the near future GPS will be widely used allowing a broad variety of location dependent services such as direction giving, navigation, etc. A family of protocols and addressing methods to integrate GPS into the Internet Protocol to enable the creation of location dependent services such as multicasting selectively only to specific geographical regions defined by latitude and longitude. For example, sending an emergency (or advertising) message to everyone who is currently in a specific area, such as a building or train station i.e. providing a given service only to a certain geographic range. Also, location aware computing helps to collect information from specific users in urgent situations to re-organize or re-distribute time constrain tasks.
Different localization systems are available today, GPS, IR sensors and DECT. Even if there are arguments against the resolution accuracy using such localization systems the technology is promising and is much more application dependent.
Clearly it would be possible to create a dedicated software system for each application area, but it would be much more cost effective if we could design and build a single, general purpose, location aware, mobile information system. This paper discuss some of the requirements for a general location aware architecture.

2. Geo routing
Geographic routing has been studied for a couple of years and has been specified in RFC 2009. It allows user to draw destination as a closed polygon which can be done by downloading Zoom-able Map Interface. Then, the polygon will be translated into GPS coordinates and the message will eventually be multicast to all clients who are located within the bounds of that polygon. the basic components in Geo-routing system are GeoRouter, GeoNode, GeoHost and client processes as described in [1]. The main challenge is to integrate the concept of physical location into the current design of the Internet which relies on logical addressing. We see the following general families of solutions:

  • GPS-Multicast solution
  •  Unicast IP routing extended to deal with geographic addresses
  •  Application Layer Solution using extended DNS that is to return IP addresses given a geographical location.

    • In [RFC-1884] and [RFC-1887] the sender of a "geographic message" would be unicasting messages only to such hosts which have geographic addresses. When we talk on location/context aware computing we need methods that attempt to provide the more general ability of sending a message to all recipients within a geographical area, regardless of whether the hosts have geographical addresses or not. Moreover, we need in depth research how a geographic routing table should be designed. Probably a Geo-router should provide a service area table, a cache of previous actions, and a tunnel table.
    The service area table contains a list of polygons describing the geographical region administered by each of the router's child nodes. Additionally, the service area of the router will also be included. The router's service area is computed by finding the convex hull surrounding all of the service areas of the child nodes.
    The cache of previous actions is a hash table which uses the identification number of a geographic message as the key. The message identification is included in the header of geographic messages. This assumes that a geographic message will actually be composed of several packets all of which are destined for the same geographic region.
    The tunnel table contains the virtual links which tie the geographic router to the whole network of geographic routers and GeoNodes. Each tunnel in the table is a virtual link to either a parent router, a peer router, or a child GeoNode. Each entry in the service area table should have a corresponding entry in the tunnel table.

    3. The impact of sensor signals on the network traffic
    Context-aware computing introduces a new dimension for future mobile computing systems, which enables greater automation of user-terminal interaction and system dynamic intelligence. Context-aware, in some cases, location-aware computing systems includes Smart Badge[2],[3],[4] Intelligent Badge[5], Active Badge[6] etc. Imagine a situation in which geographically dispersed sensors and receivers are connected over a data network. The sensors are continuously collecting large amounts of information that must be combined for one or more receivers. These sensors could be microphones, cameras or whatever device in use. A straightforward design is for the network to passively forward each packet of the input streams to each receiver. Each receiver would then do its own mixing. An alternative is to use fusion to do some of the mixing within the network, as suggested in[7]. If multiple input signals pass through the same internal node at approximately the same time, that node can mix the signals. If the mixed signal is less than the sum of its constituents, this will reduce the total network traffic. It also reduces the bandwidth and the processing needed at the end nodes.

    4. Active nodes
    Traditional data networks passively transport bits from one end system to another, i.e. the network is insensitive to the bits it carries and they are transferred between end systems without modification. The role of computation within such networks is extremely limited, e.g., header processing in packet-switched networks and signaling in connection-oriented networks.
    In location/context aware computing such networks can not suffice. Location/context aware computing break this tradition by an urgent need for active networks[8] to perform customized computation on the user data tailored according the user's location and/or context. Active network carry methods that are executed at the nodes of the network. Packets traversing active nodes, called SmartPackets, carry information on how and where to route the arriving SmartPackets at the active nodes or we called it "beacon nodes". The Beacon receives a SmartPacket and forwards it to the actual destination node based on the method stored in the SmartPacket. In this sense, the Beacon acts like a conventional router. However, as opposed to traditional routers, the Beacon itself need not be fixed. Active Nodes can be configured as Beacons as and when necessary. This one possible solution for applications location/context aware sensitive. Example, receiving your fax message always on the fax machine nearest you.

    5. Agents
    Software Agents is a computational system which has goals, sensors, and effectors, and decides autonomously which actions to take. The agent observes both the user(where he are) and the application to determine the "right thing to do". Software agents is in development technology and should become the breakbone in location/context aware computing in the near future. The mobility of agents make them a very interesting technology in location aware computing and development. Moving agents around should be one essential requirement in location aware infrastructure:

  • reduce network traffic
  • share load among machines
  • go to the data if the data can't come to you
  • user may have only infrequent connection to network
    • We believe that future applications will merge to interact with agents which are collaborated by user, i.e. agents will be able to assist users with their tasks when they are not in the right place.

    6. Conclusion
    We have discussed the general issues about the architecture of location-aware system and summarized three basic requirements towards location awareness computing and infrastructure. The geographical routing enable the system to transmit/recieve information in a restricted way. Introducing sensors as data transmitters in internetworking implies an urgent in depth research in the field of active nodes. Finally we believe that a reliable, single, and  general purpose, location aware, mobile information system could be realized with software agents technology.

    7. References
    [1] RFC 2009
    [2] H.W. Peter Beadle, B. Harper, G. Q. Maguire Jr., J. Judge, " Location Aware Mobile Computing," Proc. of IEEE/IEE International Conference on Telecommunications, (ICT'97), Melbourne, April, 1997.
    [3] H.W. Peter Beadle, B. Harper, G. Q. Maguire Jr., "Smart Badge: It beeps, It flashes, It knows when you are hot and sweaty", International Symposium on Wearable Computers, 1997.
    [4] H.W. Peter Beadle, B. Harper, G. Q. Maguire Jr., "Location Aware Computer Systems"
    [5] Abowd, G. D., Atkeson, C. G., Hong, J., Kooper, R., Long, S., and Pinkerton, M. "Cyberguide: A mobile context-aware tour guide," To appear in ACM Wireless Networks, 1997.
    [6] H.W. Peter Beadle, B. Harper, G. Q. Maguire Jr., "Location Aware Computer Systems"
    [7] N. Yeadon. Quality of service for multimedia communications, Lancaster Unversity, 1996
    [8] http://www.ittc.ukans.edu/~ywijata/classes/845/final/draft.html