Controlling telecommunication system parameters

The present invention relates to apparatus and a method of configuring the parameters of a network dependent on the geographical location of the network unit and apparatus for invoking necessary changes in the configuration of the parameters of a network.

According to a first aspect of the present invention, there is provided a method of allowing use of a movable transceiver in a temporary position in a mobile telecommunications system, which system has a plurality of other transceivers associated therewith for wirelessly transmitting data between each transceiver and terminals registered with the system, the method including determining the temporary position of the movable transceiver, determining the transmission parameters used by the other transceivers associated with the system, calculating suitable parameters usable by the movable transceiver for allowing communication between the movable transceiver and terminals registered with the system in accordance with the calculated parameters.

According to a second aspect of the present invention, there is provided the method of allowing use of a movable base station transceiver in a temporary position in a mobile telecommunications system, which system includes a plurality of cells each having a base station transceiver associated therewith for wirelessly transmitting data between the base station transceiver and terminals located in the cell, the method including determining the temporary position of the movable base station transceiver, determining the frequencies used by the neighbouring base station transceivers, calculating frequencies usable by the movable base station transceiver that will tend not to interfere with transmissions of the neighbouring base station transceivers, and allowing communications between the movable base station transceiver and terminals in accordance with the calculated frequencies.

According to a third aspect of the present invention, there is provided apparatus for allowing use of a movable transceiver in a temporary position in a mobile telecommunications system, which system includes a plurality of other transceivers associated therewith for wirelessly transmitting data between each transceiver and terminals registered with the system, the apparatus including means for determining the temporary position of the movable transceiver, means for determining transmission parameters used by said other transceivers in the system, means for calculating suitable parameters usable by the movable transceiver for allowing communications between the movable transceiver and terminals registered with the system in accordance with the calculated parameters.

According to a fourth aspect of the present invention, there is provided apparatus for allowing use of a movable base station transceiver in a temporary position in a mobile telecommunications system, which system includes a plurality of cells each having a base station transceiver associated therewith for wirelessly transmitting data between the base station transceiver and terminals located in the cell, the apparatus including means for determining the temporary position of the movable base station transceiver, means for determining the frequencies used by the neighbouring base station transceivers and means for calculating frequencies usable by the movable base station transceiver that will tend not to interfere with transmissions of the neighbouring base station transceiver and enabling communications between the movable base station transceiver and terminals in accordance with the calculated frequencies.

Apparatus and a method for allowing use of a movable transceiver in a temporary position according to the invention will now be described, by way of example only, with reference to the accompanying drawings in which: <ul id="ul0001" list-style="none"><li>Figure 1 is a diagrammatic drawing of a first scenario to which the present invention is applicable;</li><li>Figure 2 is a diagrammatic drawing of a second scenario to which the present invention is applicable;</li><li>Figure 3 is a flow diagram showing the sequence of events describing the network metamorphosis in accordance with an embodiment of the present invention;</li><li>Figure 4 is a diagrammatic drawing showing the migration of the network parameters as a mobile base transceiver station passes from a first geographical area to a second geographical area in accordance with the first scenario; and</li><li>Figure 5 is a diagrammatic drawing showing the migration of the network parameters as the mobile base transceiver station passes from a first geographical area to a second geographical area in accordance with the second scenario.</li></ul>

In the drawings, like elements are generally designated with the same reference numeral.

In order to allow mobile equipment registered with a mobile telecommunications network to operate without interference, a particular area is covered by a specific cell, each cell being served by one base transceiver station (BTS). Each cell is allocated particular frequency channels which may be used for radio transmissions between the BTS and mobile equipment within the cell. In a GSM (TDMA) network the same frequency channels are not used in neighbouring cells in order to prevent interference to radio communications occurring within neighbouring cells other parameters may also be varied to reduce or prevent interference. Other parameters may also be varied to reduce or prevent interference. Different considerations apply to CDMA networks, where system parameters for power, frequency, bandwidth, coding, modulation etc. are adapted to ensure that the system operates within the bounds of the constraints that have been configured into the unit. The invention is applicable to all types (and combination of) networks, including TDMA- and CDMA - based networks.

In the example of a GSM (TDMA) network, cells are typically of an area of 10 square miles, with smaller cells covering more densely populated areas. Mobile equipment and BTSs utilise low power transmitters, meaning that the same frequency channels can be re-used in non-adjacent cells. As a mobile telephone moves from the coverage area of a first cell to the coverage area of a second cell, there is a switch in the BTS handling any calls from the BTS associated with the first cell to the BTS associated with the second cell in a process known as "handoff". A handoff is processed by either the BTS controller (BSC) or mobile switching centre (MSC) depending on the type of handoff involved.

A different process occurs when a mobile telephone moves from a first country to a second country, known as "roaming". When a mobile telephone user crosses a national boundary, or moves into coverage of a different network when roaming, the service will become unavailable and the user will have to redial to continue the call on the new network. The handset will then scan for all the networks it can detect, and then decide which to use. The mobile telephone is then in the coverage area of a cell in the second country, associated with a new network service provider, and usage can continue with handoffs being processed by the BTS or the MSC of the new service provider. The handover from the first service provider to the second service provider therefore causes an inconvenience for a user wishing to roam as described.

In the embodiment to be described a BTS of the mobile telecommunications network is portable (that is, it operates at different geographical locations). Mobile equipment users who are subscribers to a particular mobile telecommunications network with which that BTS is associated are able to access network services as if the BTS was a conventional BTS fixed on land. Such an arrangement is particularly suited to use on a cruise liner, where a BTS could be located on the cruise liner to enable the cruise liner passengers to make mobile telephone calls. It should however be appreciated that the invention is not limited to this particular use and could instead be applied to any situation requiring a portable BTS - such as on board a train, aeroplane or any other moving vehicle.

The portable BTS may operate (that is, provide mobile telecommunication services) while it is moving between geographical locations. However, the invention is also applicable to a BTS that can be deployed at different geographical locations, but does not operate when being transported between these locations. Such an arrangement is advantageous, for example, when a BTS is required temporarily at a location - such as where a special event is held at which a large number of attendees are expected.

Current known systems employed on cruise liners and in similar situations are manually configured to operate with predetermined network parameters. For example, a mobile telecommunications system, comprising a portable BTS, operating on a cruise liner will be switched off as it approaches new territorial waters to ensure that the system is not in contravention of regulations of that new territory as the international border is crossed. When the cruise liner has travelled into the new territorial waters, the mobile telecommunications system on board the cruise liner may be made available once again to users, with the system now operating under the configuration predetermined to be compatible with the negotiated roaming agreement between the onboard system provider and the body regulating mobile telecommunications of the country governing the new territorial waters, this configuration being invoked as the system is made available on the cruise liner once again. Such an arrangement is inconvenient for users wishing to access telecommunication services via the portable BTS when the system is being reconfigured and the system is unavailable.

An alternative to this known system is not to operate that system on board the cruise liner when the cruise liner enters territorial waters. Instead, the passengers can make use of the networks provided by the country governing the territorial waters. However, this arrangement suffers from the same disadvantage - that service is interrupted when the onboard system is shut down - and also results in a loss of revenue for the onboard system operator.

The embodiment to be described is concerned with such a situation in which the cruise liner is crossing an international border, thereby requiring a change in the configuration of the onboard system parameters. Using a Network Metamorphosis Configuration Control (NMCC system), the BTS configuration is gradually migrated to a configuration predetermined to be compatible with the negotiated roaming agreement between the network provider controlling the onboard system and the body regulating mobile telecommunications of the country governing the new territorial waters. That is, the characteristics of the radio communications between the BTS and the mobile equipment are changed to be compatible with the new location. The frequency channels used, the transmission power levels and even the communication protocols (to allow BTS to operate in a different network type) may all be altered. The NMCC system therefore allows better customer service by enabling mobile communication services to be available to users uninterrupted for an increased amount of time, particularly during the crossing of international borders.

A first scenario to which the present invention is applicable is the situation of a cruise liner 1 leaving the territorial waters W_A of Country A and travelling into the territorial waters W_B of Country B, and is shown in Figure 1. The cruise liner 1 has onboard a BTS 3 associated with a mobile telecommunications network, allowing passengers who are subscribers to the particular mobile telecommunications network associated with that BTS 3 to access network services using their mobile equipment as if the BTS 3 was a conventional BTS of that network fixed on land. The traffic from the BTS 3 is transmitted to a satellite and from there to the particular network (although any other means for transmitting this traffic from the BTS 3 could be used). Subscribers to different networks which have a roaming agreement with the network operating the onboard BTS can also obtain service.

Before the international border is reached, the cruise liner 1 is in the territorial waters W_A of Country A and a network (network "N") utilising the BTS 3 will be configured to operate that BTS 3 within the parameters predetermined by the negotiated roaming agreement between the network N provider and Country A. This agreement ensures that the portable BTS 3 located on the cruise liner 1 operates in a manner that is compatible with the technological capability of the BTS controllers (BSCs) of Country A. The agreement also ensures that the portable BTS 3 complies with the regulations of Country A concerning, for example, permitted transmission power levels and permitted radiation levels. Additionally, the agreement will include certain frequency channels allocated to the network N provider to ensure that the portable BTS 3 does not interfere with other BTSs located in Country A.

The parameters predetermined by the negotiated roaming agreement between the network N provider and Country B may differ from the parameters predetermined by the negotiated roaming agreement between the network N provider and Country A. For example, the permitted transmission power levels and permitted radiation levels may be different. The technological capability of the BSCs of Country B may also be different (Country A may operate one network type, for example GSM, while Country B operates a different network type, for example IS-95).

The cruise liner 1 contains a NMCC unit 5 which is able to determine the precise location of the BTS 3 using any suitable means, for example using a satellite navigation system such as the Global Positioning System (GPS) or cell triangulation. The NMCC unit will therefore be aware of the cruise liner 1 (and hence the BTS 3) approaching an international border 7. There exists an area 9 extending, for example, 15 kilometres into the territorial waters either side of an international border 7 in which the telecommunications network N is able to operate within the parameters compliant with the regulations of both Country A and Country B. The NMCC unit is therefore able to gradually migrate the telecommunications network N operating through BTS 3 from the parameters predetermined by the negotiated roaming agreement between the network N provider and Country A to those parameters predetermined by the negotiated roaming agreement between the network N provider and Country B, as will be described hereinafter.

Figure 2 describes a second scenario, in which the cruise liner 1 of Figure 1 is instead leaving international waters W_INTL and travelling into the territorial waters W_C of Country C. Before the international border is reached, the cruise liner 1 is in international waters W_INTL and the network N utilising the BTS 3 will not be under any regulatory constraints. The network N will therefore be able to use any appropriate frequency channel without the risk of interference.

The NMCC unit 5 contained onboard the cruise liner 1 uses its satellite navigation system such as GPS to determine when the cruise liner 1 (and hence the BTS 3) is approaching an international border 7. When such an international border 7 is approached, the NMCC unit 5 is therefore able to gradually migrate the parameters used by BTS 3 from the parameters currently being used in the international waters to those parameters predetermined by the negotiated roaming agreement between the network provider and Country C, as will be described hereinafter.

Whilst the cruise liner 1 is in the territorial waters of Country A,B or C, the GPS may also be used to alter the frequency channels used by the BTS 3 as the cruise liner 1 moves around. For example, when the cruise liner 1 nears the coast of a country, fixed BTSs on land will provide coverage in a area overlapping with the coverage provided by the onboard BTS 3. To prevent interference, it is necessary for the frequency channels used by BTS 3 to be selected from those available in the relevant country so as not to conflict with frequency channels used by a neighbouring fixed BTS. When the position of the onboard BTS 3 is known, this allows the appropriate frequency channels for that BTS 3 to be calculated, if the frequency channels used by the neighbouring fixed BTS are known. This calculation can be done, for example, by the NMCC units.

Figure 3 is a flow diagram showing the sequence of events describing the network metamorphosis and occurring in the NMCC unit 5 as the cruise liner 1 and the portable BTS 3 approach new territorial waters. This flow diagram is applicale to both the first scenario (in which case the network parameters are being migrated from a first particular configuration as predetermined by the negotiated roaming agreement between the network provider and Country A to a second particular configuration as predetermined by the negotiated roaming agreement between the network provider and Country B) and the second scenario (in which case the network parameters are being migrated from a first particular configuration without regulatory constraints with the cruise liner 1 in international waters to a second particular configuration as predetermined by the negotiated roaming agreement between the network provider and Country C).

The sequence of events describing the network metamorphosis as the cruise liner 1 approaches an international border 7 starts with block 11. At block 13 the NMCC unit 5 receives geographical information from the GPS. The NMCC unit 5 then determines whether or not an international border 7 is approaching (decision block 15). If the cruise liner 1 is not approaching an international border 7, the NMCC unit 5 maintains the current network parameters (block 17) which are either configured to operate within the parameters predetermined by the negotiated roaming agreement between the network N provider and Country A (in the first scenario) or configured to operate without regulatory constraints (in the second scenario). The NMCC unit 5 continuously receives geographical information from the GPS (block 13) and monitors continuously whether or not an international border 7 is approaching (decision block 15).

When the NMCC unit 5 determines that the cruise liner 1 is approaching an international border 7 (at step 15), it starts the network migration process described by block 19 by gradually migrating the network parameters used by BTS 3 from the parameters predetermined by the negotiated roaming agreement between the network N provider and Country A to those parameters predetermined by the negotiated roaming agreement between the network N provider and Country B (in the first scenario). Alternatively, and in the second scenario, the network migration process described by block 19 of Figure 3 involves gradually migrating the network parameters used by BTS 3 from the parameters used in international waters, and therefore configured to operate without regulatory constraints, to those parameters predetermined by the negotiated roaming agreement between the network provider and Country C. After a predetermined period of time the NMCC unit 5 will check the progress of the network migration (decision block 21). If the NMCC unit 5 determines that migration from the first network configuration to the second network configuration is incomplete, it will continue the network migration process as indicated by block 23 of Figure 3. In this case, the NMCC unit 5 will check the progress of the network migration repeatedly at predetermined time intervals (decision block 21). Once the NMCC unit 5 determines that the network migration process is complete, the network metamorphosis ends as indicated by block 25.

Figure 4 details the migration of the network parameters that takes place at block 19 of Figure 3, in the first scenario. The NMCC unit 5 may implement a remote resource algorithm which calculates the necessary changes in the configuration of the parameters based on GPS information, the presently used network parameters and the network parameters applicable to networks operated in the country being approached, or the necessary changes in the configuration of the parameters may be invoked by any other suitable means - for example using data from the network N sent via the satellite link. At step 27, the NMCC unit 5 has not started the migration process and the network parameters P_A are configured to operate within the pre-negotiated roaming agreement between the network N provider and Country A. As the migration process starts, a new set of parameters P_A/B (consisting of a hybrid of the parameters pre-negotiated with Country A and the parameters pre-negotiated with Country B) are introduced at step 29. At this point the BTS 3 is able to operate within the parameters designated by P_A and also within the parameters designated by P_A/B. As the migration process continues the original parameters P_A are made unavailable (step 31). At this point, the network is reliant on the hybrid parameters P_A/B (that is calls between mobile equipment and the onboard BTS 3 will be made only in accordance with those parameters). At step 33 the parameters P_B, which are configured to operate within the pre-negotiated roaming agreement between the network N provider and Country B, are introduced allowing the network N to operate within the parameters designated by P_A/B and also within the parameters designated by P_B. To complete the migration process, the hybrid parameters P_A/B are made unavailable at step 35, thereby allowing the network N to only operate using the parameters P_B configured to operate within the pre-negotiated roaming agreement between the network provider and Country B.

The "hybrid" parameters P_A/B are parameters that are acceptable for use in both Country A and Country B.

Figure 5 details the migration of the network parameters that takes place at block 19 of Figure 3, in the second scenario. Again, the BTS 3 may include a remote resource algorithm which invokes the necessary changes in the configuration of the parameters, or the necessary changes in the configuration of the parameters could be invoked by any other suitable means. At step 37, the NMCC unit 5 has not started the migration process and the network parameters P_INTL are operating without regulatory constraint as the cruise liner 1 is in international waters. As the migration process starts, a new set of parameters P_INTL/C (consisting of a hybrid of the parameters used in international waters and the parameters pre-negotiated with Country C) are introduced at step 39. At this point the BTS 3 is able to operate within the parameters designated by P_INTL and also within the parameters designated by P_INTL/C. As the migration process continues the original parameters P_INTL are made unavailable (step 41). At this point, the BTS 3 is able to operate using the hybrid parameters P_INTL/C. At step 43 the parameters P_C, which are configured to operate within the pre-negotiated roaming agreement between the network provider and Country C, are introduced allowing the BTS 3 to operate within the parameters designated by P_INTL/C and also within the parameters designated by P_C. To complete the migration process, the hybrid parameters P_INTL/C are made unavailable at step 45, thereby allowing the BTS 3 to only operate using the parameters P_C configured to operate within the pre-negotiated roaming agreement between the network provider and Country C.

The parameters P_A, P_B, P_C and P_MTL include details of frequency channels that are available in that territory. As discussed above, within any territory, different BTSs will use frequency channels for communication with mobile equipment that are selected from those available so as not to interfere with radio communications in neighbouring cells.

When all BTSs are fixed, the frequency channels for each BTS can be predetermined and it is not necessary to change them in real time. However, when the onboard BTS 3 moves within a territory, the frequency channels used by the BTS 3 are varied in accordance with a determination of the position of the BTS 3 (by GPS) and data indicating the frequency used in different areas (cells) within the territory. An algorithm on the NMCC unit 5 uses this information to calculate in real time frequency channels that should be used which will avoid interference with neighbouring cells. The BTS 3 will change the frequency channels used by the mobile equipments communication with it in dependence upon this calculation to provide continuous service within a country.

In another embodiment, a BTS is provided that can be employed temporarily in a desired location. For example, a temporary BTS may be required where extra network capacity is needed. The BTS is transported to the desired location, during which time it is inoperative. When the BTS is deployed in the desired location, its NMCC determines the position of the BTS (for example using GPS or by manual entry of this data). This position information, in conjunction with data indicating the frequency channels used in neighbouring cells, enables the NMCC to select suitable frequency channels for use by the BTS that will not interfere with neighbouring cells.