Mobile communications system.

Mobile phone system.- Mobile phone system

The invention relates to a mobile telephone system and more particularly to the control and structure of such systems.

In known cellular radio systems, such as that shown in Figure 1, the system comprises a number of base stations 10, 13, 16, each connected to a local exchange 11, 14, 17 of the mobile telephone system (i.e. to the relay locations of the mobile telephone system). Blocks 11, 14 and 17 are connected to a telephone exchange (e.g. British Telecom) to the network via dialers 12, 15 and 18, which allow connection to geographically remote users via dials 22, 25 and 28, exchanges 21, 24 and 27 and base stations 20, 23,

26 through. To illustrate the operation of users 30, it has been shown to communicate with users of telephones 46 and 45, respectively.

Users 30 and 31 randomly use the same base station

13, and users 45 and 46 use geographically close stations 23. Active exchanges 14 and 24 transmit speech information between users and also provide location control information, whereby speech and control information is transmitted as digital data packets through the telephone exchange network (which may include digital exchanges 15, 25 fiber optic connections).

When a mobile user (e.g., user 30) gets closer to a base station 16, the system is able to connect to a geographically closer base station, and in practice the user's telephone asks the base station to accept the transfer, and this is handled by the exchange 17 to ensure that the call is routed to the correct destination. Therefore, the selector 18 must establish a connection to the selector 25 (as shown by the dashed line connection).

As popularity grows - due to the higher traffic density, the structure of Figure 1 becomes saturated when the number of users initiating a call or moving to another base station area is large.

Globecomm 88 Foster and Adams: The ATM Zone Concept describes a possible solution using a network architecture based on ATM (Asynchronous Transfer Mode).

The present invention relates to a mobile telephone system with improved features in which this zone concept can be utilized.

According to the invention, there is provided a mobile telephone system characterized by the features set forth in the characterizing part of claim 1.

According to the invention, there is further provided a method for controlling a mobile telephone system having a plurality of base stations, the method being characterized in that the method comprises the steps of: providing a routing route for establishing a connection from any base station to any other base station; generating packet control information and packet data information at each station; and providing tracking at each station of the current physical address of the mobile terminal in the packet-switched network to which control and / or data packets are to be transmitted and from which control and / or data packets are received.

The invention will now be explained by way of example with reference to the accompanying drawings, in which:

Figure 1 shows a known mobile telephone system;

Figure 2 shows an embodiment of the present invention;

Figure 3 shows the packet structure of an asynchronous transfer mode (ATM);

Fig. 4 shows the base station of Fig. 2 and the associated connections 5 in more detail;

Figure 5 shows in more detail the network selectors of Figure 2; and Fig. 6 shows a structure for the router 40 of Fig. 2.

Figure 2 illustrates a system in which the exchanges 11, 14, 17, 21, 24, 27 of Figure 1 are no longer required, and which provides a distributed system with sufficient intelligence for local processing of control information.

Each base station is associated with a control interface unit 10a, 13a, 16a, 20a, 23a, 26a. Users 30, 31 communicate with the base station 13 and the digital speech signals and other information from them pass to the control interface 13a, where control information and packetized speech information are generated. . is routed through a routing block 40 (which is a cross-switch / hub) and selectors 50 and 52 to a routing block 41 (which is also a cross-switch / hub) and to base stations 23a via a control interface 23a. In addition to the control information, in the interface • · '·. * · 13a, a packetized speech is developed for each user. ^l...^: the address of the destination received by that remote «· <

tj: on the user interface plate 23a. The destination address that accompanies this voice packet allows the dialers 50 j '.., - 52 to determine the route of the call so that the confirmation. reception at the correct destination. As shown in Figure 3 • · · •, the speech / control information is transmitted in the form of a packet with the destination address in the packet header. The connection made by the selectors 50 52 is based solely on the value of the quantity.; · The address of the head.

Traffic flexibility is achieved by using the Asynchronous Transfer Mode (ATM) method.

The connection of several base stations to the ATM switching node can be achieved using the tree and branch structure of the Passive Optical Network (PON). Other structures, such as a ring structure, are not excluded. If a single address is assigned to each PON for address-routed ATM packets, then such packets are sent to all base stations associated with the PON. An additional identifier that determines which ATM packets are associated with a particular base station is obtained from the connection number stored in a separate 16-bit field for each packet.

As shown in Figure 3, ATM packets include an information field and a header. The contact number would be included in the information field with the speech information. The header is provided with a header error checking field (HEC) and a destination address field. The destination address field may comprise two parts, i.e. a Virtual Path Identifier (VPI) and a Virtual Channel Identifier (VCI). The VPI divides the ATM packet stream into separate payloads. It can be used to differentiate between utilities with different quality of service requirements (i.e., tolerating packet loss rates and end-to-end delays in different ways), and has a limited ability to distinguish between utilities that require different routes. The size of the VPI field and its uses in the targeted Integrated System Digital Network (B-ISDN) are currently much discussed in standardization30 paths, but could typically be 8 bits (see also JL Adams: The Virtual Path Identifier and its Applications for Routing and Priority of Connectionless and Connection Oriented Services; International Journal of Digital and Analog Cabled Systems, 1989).

In order to provide destination addresses for, for example, hundreds of thousands in the United Kingdom

For PONs required after 2000, it has been proposed to reserve a few VPI values ​​(e.g., 8 values). Each VPI value represents an address 'block' with 64k addresses defined by ar5 in the 16-bit VCI field. The entire address space, which is an integer multiple of 64k, can be considered an ATM zone.

Half of the reserved VPI values ​​are used to transmit signaling information, and such packets are also transmitted with a higher priority through the ATM network (i.e., such packets are ignored with a lower probability). It defines a signaling path in each direction between the two destinations of each calling and called client of any given connection. This signaling 15 channel is configured as a high capacity channel (broadband bit rate) that can quickly transfer information between each end (e.g., on a 1000 km route through an ATM network, the average delay in the other direction is about 10 ms, including packetization). When the channel is not in use, its capacity can be momentarily allocated to other users on a known VPI multiplexing principle. There are other signaling routes between the base station and controllers elsewhere in the network, in which case the routes are identified by appropriate VPI signaling values ​​as well as specific VCI values. Other reserved VPI values ​​are used to transfer voice packets from the base station to the base station without changing the packet header.

The addresses of the PON destination act as group addresses, i.e. the address already assigned for the 30-band PON also applies to all other PONs with adjacent cells. In ATM cross-connect (blocks 40 and 41 in Figure 2), ATM packets containing group addresses are automatically distributed to all relevant PONs.

Other aspects of packet handling may be based on the methods disclosed in EP Patent Publication No. 168265.

The purpose of the router 40 is to allow several geographically close base stations 10, 13 and 16 to be concentrated in the same selector 50 and to act as a cross-switch 5 so that speech and information addressed to the base station 13 can also be distributed to the base stations 10 and 16. As a result, the user 30 can move away from the base station 13 towards station 16, whereby this base station can take over the connection task so that there is no call loss. Block 40 could be duplicated using base stations 16 as an upper base station group, and other base stations (not shown) could be connected to handle the transition from station 16 to lower stations.

Thus, the system is flexible enough to handle speakers moving from one base station to another during a call, and the interface can map the locations of remote users so as to ensure proper routing of calls. The size of a cell normally used for mobile connections can be practically reduced to minicells using this method (e.g. a radius of 100 m) so that the number of users per cell is reduced and congestion is reduced in areas with high traffic needs. The resulting increase in the number of cells is not a disadvantage in terms of coupling, due to the proposed simplified coupling / routing mechanism. _e from and the rapid tracking feature of the destination indication.

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^l.· ^: The structure described above in Figure 2 forms the basis for the control of the beach from the base station to the base station. This removes the processing load from the central controller and thus removes a potential processing bottleneck, especially as the system evolves toward wider use of microcells. When either client moves, the ATM zone format '···' 35 automatically issues a new route for speech and a new · ', · route for signaling information. The construction of a different route / ·, · involves a very small delay and a low processing load98585 myth, because the route to any destination is already predefined. Capacity previously used on the old route, which is no longer needed, is automatically made available to other users in accordance with the principles of VPI multiplexing5.

Destination assignment also simplifies data transmission for wireless services such as mobile terminals.

Figure 4 shows a structure for processing information at the base station level.

One of the base station interface units 13a is shown having a base station interface 73 for voice channels and an interface 74 for a base station signaling channel. Interface 75 is provided for speech packets and interface 76 for signaling associated with packets connected to the bus block 40. Connection 73 passes at interface 13a to a packet generator / decompressor 69, which takes digital speech information from the voice channels and packets it in block 69 for transmission to the voice packet queue in the router 40. The packet counter 70 counts the outgoing packets and produces an invoice result and a connection number associated with the packets, so that in block 72, the charging information can be calculated under the control of the microprocessor 61. Microprocessor 61 also has access to base station signaling information via interface 74 and remote station packetized signaling information via packet originator / decompressor 68. The microprocessor directs the information from the free access numbers to the memory 62 and the customer identification information to the memory 63. It also handles the terminal's own PON address for memory 64, the destination PON address for memory 65, the connection number for memory 66, and the anchor address for memory block 67. The contact number memory 66 determines, based on the information stored therein, whether the decompressor 69 should discard the incoming packetized information so as to avoid storing unnecessary packets.

Thus, for a mobile terminal currently associated with a particular cell / microcell, all base stations in its group address area store the current PON address of that terminal, the current destination PON address, and the connection number and anchor controller address (explained below). This information is stored in the tables at each base station by an incoming broadcast message, i.e. both ends of the ongoing call are responsible for updating the group tables at the other end.

The group table update mechanism is triggered whenever a terminal moves to an adjacent cell, minicell, or microcell. In this case, the new base station sends a signaling message to the destination PON address containing the client ID of each end, the anchor controller address, the destination PON address, and information about the updated near end PON address and connection number if the values ​​of these parameters have changed. In response, the base station associated with the other end terminal transmits the current values ​​of the same para20 meter list, whether or not they have changed.

Connection numbers must be changed whenever the PON address changes. Each base station in the PON group can be pre-assigned access number blocks that contain free access numbers so that a new access number can be automatically dialed at any base station as the terminal moves from one PON group to another.

ATM packagers at base stations automatically add destination PON addresses to voice packet headers. This is the only action required to route the packet. Base stations use packet counters for charging. In connection with the transfer to the new base station, the old base station transmits the charging information using ATM signaling packets in which the destination address determines the anchor controller. This controller is the only fixed point in the architecture from which the name anchor is derived. There are many copies of the anchor in the zone, and one of these is associated with a specific call when connecting. Its function remains throughout the call. Using the zone concept, there is always a mass ATM bus to all anchor controllers from any base station.

Maintenance and monitoring can also be included in the control functions. Technical equipment compatible with the GSM system (Groupe Speciale Mobile - Trans-European Network) may be used.

As explained with reference to Figure 2, selectors 50-52 are capable of processing information produced by base stations and associated interfaces, and in practice would be part of a larger network of selectors (typically nationwide). The selectors can be configured as shown in Figure 5.

One of the selectors is shown with an incoming packet interface 85 for receiving packets from routers 40 or another selector 51. A fault condition input 86 is also provided for detecting faults on a given bus. The packages of selector 50 are available for transmission at interface 87.

Incoming packets are routed in the selector 50 to the FFO memory 90 (the first stored is read first). The destination address in the packet header is available to the header translator 91. This information includes VPI and VCI numbers. This information is used in the header translator 91 and the primary route block 92 to select the most preferred route based on the stored route information, and such header information of the selector is made available to the actual selector block 93, which connects the information field of the FIFO memory 90 appropriately. After coupling, the information field is passed to a header compiler 94, where it is converted to a destination address with VPI and VCI parts. It can then be used for transmission from interface 87.

When a route fault occurs, it is indicated by a microprocessor 96 which instructs the compiler 91 to select an alternative preferred route for switching.

Thus, ATM Cross-Connections and ATM Switches are configured to handle assignment mechanisms provided by base stations and are compatible for zone operation. This means that the destination address is retained from the selector output to the output and is thus retained from end to end of the route. At input 85 of the selector, the VPI and VCI numbers are used to refer to specific routing tables in block 92 for zone packets and an internal route address flag is generated. This address flag has enough space for the destination address as well as information to direct the ATM packet to the correct output.

As explained, routing tables can take into account fault situations by storing primary and secondary. . its output with suitable routing address labels for internal selector functions. An automatic fault alarm «(· '25 would cause the routing tables to switch to the secondary output of the field if necessary.

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Routing tables are the only special means of moving * · · ......

XJ · users, and the same ATM switches can be used for other B-ISDN services if required.

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Although the system has been described in a form in which information packets are generally distributed to all neighboring base stations so as to ensure uninterrupted operation of mobile users, in an alternative embodiment, a prediction mechanism can be used to validate. 4 · The user's route can be predicted from the current and previous address information, so as to limit the number of adjacent stations to which the information is copied or shared in order to reduce the bandwidth requirements.

As shown in Figure 6, the router 40 could be configured as a ring mechanism 100 in which a plurality of nodes 101 to 104 are capable of processing packetized information. Node 104 has a prediction block 106 that includes a memory 107 for connection numbers and a memory 108 for destination addresses 10. Depending on the user's location changes, the predictor determines the stations that are currently suitable for receiving packets depending on the movement pattern, and then adds instructions to the packetized information to circulate the ring, giving other sols 101-103 instructions to accept or reject the received packets. .

The information to be used by the predictor 106 can be generated in the base station interface units, for example unit 13a.

For example, customer identification information is available from block 63 and changes can be routed through microprocessor 61 to predictor 106.

'Although the system has been described as mainly handling packetized speech information (i.e. speech data), it could' 'handle other packet information (e.g.

* · Computer data).