Abstract:
A local area network comprises a plurality of access points. Each access point includes a first transceiver for wireless communication with one or more user workstations. The access points include second transceivers for wireless communication with one another. At least one of the access points is configured for movement to enable re-configuration of the local area network.

Description:
FIELD OF INVENTION  
         [0001]    This invention relates to a local area network (LAN), that is to say a high bandwidth computer network operating over a relatively small area, such as an office or group of offices.  
         BACKGROUND TO THE INVENTION  
         [0002]    Typically, a LAN includes a plurality of access points hardwired together, the access points being positioned at appropriate positions in a building or group of offices. Each access point may act as a base station for wireless communication with a number of users of the LAN. For example, as shown in FIG. 1, one floor, indicated generally by the reference numeral  1 , of a building could be provided with nine access points  2   a  to  2   i,  the access points being interconnected by hardwiring  3 . Each of the access points  2   a  to  2   i  communicates with user workstations (not shown) using the Internet protocol.  
           [0003]    The disadvantage of this type of LAN is that it is difficult to reconfigure to accommodate movement of users from one part of the floor to another, particularly where high-usage access points exist. Thus, if the access point  2   d  is fully utilised, and a user moves into the vicinity of that access point (either from one of the other access points or as a new user), the LAN will not be able to accommodate such a user. In this connection, it will be appreciated that, although in theory such a new user could be accommodated, in that communication with the access points would be possible, in practice communication for that user (and all other users of that access point) would become intolerably slow. In such a case, it would be necessary to provide an additional access point, and to hardwire this additional access point into the existing hardwired network.  
         SUMMARY OF THE INVENTION  
         [0004]    The present invention provides a LAN comprising a plurality of access points, each access point being provided with a first transceiver for wireless communication with one or more user workstations, wherein the access points are provided with second transceivers for wireless communication with one another, and wherein at least one of the access points is configured for movement to enable reconfiguration of the LAN.  
           [0005]    In preferred embodiments, each of the access points will be configured for movement.  
           [0006]    In a preferred embodiment, each access point configured for movement is provided with propulsion means for moving that access point to enable reconfiguration of the LAN.  
           [0007]    Advantageously, each access point configured for movement is provided with a buoyancy device, the buoyancy devices being such that, in use, the access points can be positioned so as to float at predetermined heights. A respective helium balloon may constitute each of the buoyancy devices. Preferably, each of the helium balloons is such that its buoyancy substantially matches the combined mass of the associated access point and propulsion means.  
           [0008]    Preferably, a respective electric motor and propeller constitute the propulsion means of each access point configured for movement.  
           [0009]    Alternatively, the LAN may further comprise a tracking along which the access points can be propelled. Each access point configured for movement may be provided with a support wheel engageable with the tracking.  
           [0010]    In a preferred embodiment each first transceiver is arranged to communicate with the or each associated user workstation using the Internet protocol. Preferably, the second transceivers are arranged to communicate with each other using the IEEE 802.11b, the IEEE 802.11a, or the HiperLAN/2 protocol.  
           [0011]    In a further aspect, the invention provides an access point for a local area network comprising a first transceiver for wireless communication with one or more user workstations, a second transceiver for wireless communication with other access points, wherein the access points is configured for movement to enable reconfiguration of the local area network. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]    The invention will now be described in greater detail, by way of example, with reference to the drawings, in which:  
         [0013]    [0013]FIG. 1, as previously described, is a schematic view of a known form of LAN  
         [0014]    [0014]FIG. 2 is a schematic view of a LAN constructed in accordance with the invention;  
         [0015]    [0015]FIG. 3 is a schematic view of one of the access points of the LAN of FIG. 2;  
         [0016]    [0016]FIG. 4 is a schematic representation of two access points of a modified form of LAN constructed in accordance with the invention;  
         [0017]    [0017]FIG. 5 is a schematic representation of another modified form of LAN constructed in accordance with the invention; and  
         [0018]    [0018]FIG. 6 is a schematic view of one of the access points of the LAN of FIG. 5. 
     
    
     DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0019]    Referring to the drawings, FIG. 2 is a drawing of one floor, indicated generally by the reference numeral  11 , of a building provided with a LAN having nine access points  12   a  to  12   i.  As shown in FIG. 3, the access point  12   a  includes a first and second transceivers  13  and  14 , respective antennas  13   a  and  14   a  associated therewith, and controller  15 . The remaining access points  12   b  to  12   i  are of similar construction. Each of the transceivers  13  is configured to use the Internet protocol, and each of the transceivers  14  is configured to use the IEEE802.11b protocol (which operates at 2.4 to 2.4835 GHz).  
         [0020]    Each of the access points  12   a  to  12   i  communicates with one or more user workstations (not shown) in the vicinity thereof using its first transceiver  13 . The access points  12   a  to  12   i  communicate with one another using their second transceivers  14 .  
         [0021]    It will be apparent that the LAN described above is considerably easier to reconfigure than the known LAN. Thus, as the access points  12   a  to  12   i  are not hardwired together, they can be moved around the floor of the building to accommodate different user configurations. Thus, if a group of users moves from one part of the floor served by a first access point to the vicinity of another access point which is already fully utilised, the first access point could be moved with the users, thereby maintaining good utilisation. Alternatively, an additional access point (not shown) could be installed to accommodate the new users. In either case, the reconfiguration is relatively simple, as there is no hardwiring to modify.  
         [0022]    [0022]FIG. 4 includes two access points  22   a  and  22   b  of a modified form of the LAN of FIG. 2. Each of the access points  22   a  and  22   b  is attached to a respective helium balloon  23 , so that the access points can float in the air. Each access point  22   a  and  22   b  is also provided with a small electric motor  24  which can be used to power an associated propeller  25 . The buoyancy of each of the helium balloons  23  is such that it just matches the combined masses of the associated access point  22   a,    22   b  and the associated motor  24  and propeller  25 . The access points  22   a  and  22   b  can, therefore, be positioned, for example, in the ceiling region of an open plan office for communication with respective groups of users.  
         [0023]    The access points  22   a  and  22   b  are, apart from the provision of the balloons  23 , motors  24  and propellers  25 , identical to the access points  12   a  to  12   i  of the embodiment of FIG. 2, and so interact with one another and with the user groups in a similar manner. This embodiment has, however, an additional advantage in that an access point can more easily be moved from place to place. Control of the movement of the access points can be carried out from a central control station (not shown) under software control.  
         [0024]    As an alternative to moving the access points using electric motors and propellers, they could be provided, instead, with air jets. It would also be possible to mount the access points on tracking provided within the ceiling region of a building. Thus, as shown in FIG. 5, a modified form of the LAN of FIG. 2 is provided in a floor, indicated generally by the reference numeral  31 , of a building. The LAN has nine access points  32   a  to  32   i,  each of which is moveable along a tracking  33  provided in the ceiling region of the floor  21 . As shown in FIG. 6, the access point  32   a  includes first and second transceivers  43  and  44 , and respective antennas  43   a  and  44   a  associated therewith. The access point  32   a  is provided with a support wheel  45  which is rotatably mounted on a support structure  46 . The wheel  45  is engageable with the track  33  to enable the access point  32   a  to be moved therealong. The access point  32   a  can be moved either by hand, or by any suitable form of propulsion means such as those described above with reference to the access points  22   a  to  22   i.  The remaining access points  32   b  to  32   i  are similar construction. As with the embodiment of FIG. 2, each of the transceivers  43  is configured to use the Internet protocol, and each of the transceivers  44  is configured to use the IEE802.11B protocol.  
         [0025]    It will be apparent that any LAN of FIG. 5 has similar advantages to the LAN of FIG. 2, in that it is considerably easier to reconfigure the known LANs. Thus, as the access points  32   a  to  32   i  are not hardwired together, they can be moved along the tracking  33  to accommodate different user configurations. It would also be possible to install one or more additional access points to accommodate new users. In either case, the reconfiguration is relatively simply, as there is no hardwiring to modify. It will also be appreciated, however, that in some cases it may be desirable to have a LAN in which some of the access points are fixed and some are movable—this may be desirable, for example, where a part of the demand is expected to remain fixed for a long period of time.