GB2332821A

GB2332821A - Call billing based on distance between base station and mobile station

Info

Publication number: GB2332821A
Application number: GB9727174A
Authority: GB
Inventors: Howard Thomas
Original assignee: Motorola Ltd
Current assignee: Motorola Solutions UK Ltd
Priority date: 1997-12-24
Filing date: 1997-12-24
Publication date: 1999-06-30
Also published as: GB9727174D0

Abstract

In a cellular telecommunication network, the distance between a base station 8 and a mobile unit 15 is measured and is used to determine the call charge. The distance between the base station 8 and the mobile unit 15 may be computed by comparing transmitted and received signal strength or by measuring the time taken by a test signal to travel between the mobile unit 15 and the base unit 8. An area within a predetermined distance 14 of the base station may be designated a cheap call rate zone 13 and a mobile unit 15 found to be within this area may be charged at a lower call rate. Means may be provided to inform the mobile unit 15 that it is within the cheap call rate zone 13 and the distance computation may be carried out at the base station 8 or mobile unit 15. By inducing the subscriber to make calls close to the base station 8 the power required to support a call is kept to a minimum, thereby reducing the likelihood of interference in nearby cells and extending the battery life of the unit 15. More efficient re-use of communication signal frequencies in close proximity to a base station is also facilitated.

Description

CALL BILLING SYSTEM FOR MOBILIZE R TELECOMM11NICATION NEIWORB This invention relates to radio communication systems and particularly to means for billing calls made from a mobile station.

Radio systems provide users of radio subscriber units with wireless communications. A particular type of radio system is a cellular radiotelephone system such as the GSM system (Global System for Mobile Communications), a description of which can be found in the book "The GSM System for Mobile Communications" by M. Mouly and M. Pautet.

A particular type of radio subscriber unit is a cellular radiotelephone subscriber unit, sometimes referred to as a mobile station. Cellular radio telephone systems generally include a switch controller coupled to the public switched telephone network (PSTN) and a plurality of base stations.

Each of the plurality of base stations generally defines a geographic region proximate to the base station to produce coverage areas. One or more mobile stations communicate with a base station that facilitates a call between the mobile station and the public switched telephone network. The base station provides radiotelephone communication service between mobile stations operating in the cell and the PSTN. The communication link over a carrier signal from the base station to a mobile station is referred to as the downlink. Conversely, the communication link from a mobile station to the base station is referred to as the uplink.

The network components of a GSM cellular system are shown in Figure 1.

GSM networks are made up of mobile services switching centres (MSC) 1, base station systems (BSS) 2 and mobile stations (MS) 3. These three entities can be broken down further into smaller entities such as within the BSS there are base station controllers, base transceiver stations and transcoders.

With the MSC 1, BSS 2 and MS3, the network can make calls, receive calls, perform billings, etc as any normal PSTN network would be able to do.

Each MSC comprising the GSM network is connected to a PSTN 4. The mobile services switching centres are usually also connected to an operations and maintenance centre (OMC 5) which enables the network operator to configure and maintain the network from a central location.

Mobile stations 3 within the cellular network are located in cells 6. These cells are provided by the base station systems 2. Each BSS2 can provide one or more cells dependant on the manufacturer's equipment. The cells are normally drawn as hexagonal but in practice they are irregularly shaped.

This is as a result of the influence of the surrounding terrain or of design by the network planners.

One feature of the GSM air interface allows the base transceiver stations and mobile stations to adjust their power output to take account of the distance between them. The closer the mobile station is to the base station, the less power it and the base station will be required to transmit. This feature saves radio power at the mobile station and helps to reduce cochannel and adjacent channel interference. Both uplink and downlink power settings can be controlled independently and individually at the discretion of the network operator. Initial power setting for the mobile station is set by the information provided on a broadcast control channel for a particular cell. The base station system 2 controls the transmit power of both the mobile station 3 and the base transceiver station. The received mobile station power is monitored by the base station system and the received base transceiver station power is monitored by the mobile station and then reported to the base station system. Using these measurements, the power of both mobile station and base transceiver station can be adjusted accordingly.

The mobile station 3 consists of two parts, a mobile equipment and an electronic smart card called a subscriber identity module (SIM). The mobile equipment is the hardware used by the subscriber to access the network. The hardware has an identity number associated with it, which is unique for that particular device and permanently stored in it. The SIM is a card which plugs into the mobile equipment. This card identifies the mobile subscriber and also provides other information regarding the service that the subscriber should receive. By making a distinction between the subscriber identity and the mobile equipment identity, the network can route calls and perform billing based on the identity of the subscriber rather than the equipment or its location. Billing is computed in the charging and billing centre CBC 7 which is linked to the MSC 1.

There are two main aspects to the relationship between an operator and its subscribers. Firstly, a commercial dialogue must be initiated which would lead to a subscription relationship being established. ie an entitlement to obtain service from the network which requires actions on the network equipment so that the subscribers are recognised as such. The second aspect is billing and accounting. The operator must calculate the call charges and bill its own subscribers.

A commercial structure which is becoming more common is based on the concept of service providers. Service providers are companies, usually distinct from the operator, who take the responsibility for the commercial contact with the customers. This includes typically, the establishment of the subscription and the dispatch of bills to the subscribers. Usually, the operator bills globally the service provider for all the charges related to the subscribers managed by the latter and provides the service provider with toll ticket information necessary to produce the individual bills. This requires recording mechanisms in the traffic handling part of the system so that sufficient data is recorded for reach chargeable service.

Toll tickets are individual records generated for each call which contain the information necessary to calculate a call charge and are created by the mobile service switching centres. Information related to billing includes date and time of the beginning of the call, its duration, the called number and the identity of the subscriber. This information is relayed from the MSC to the CBC operated by either the service provider or network operator.

In currently operational cellular systems, there is no financial incentive for a subscriber to use his mobile station in a particular geographical area.

That is, he is charged the same amount for a call (of a set duration and to a particular location) irrespective of which cell he is situated in and irrespective of the distance between him and his nearest base station system.

There may be advantages to the network operator in encouraging a subscriber to situate himself close to a base station while the subscriber is making his call. This would benefit the operator in that the base station output power needed to communicate with the subscriber could be kept to a minimum, thereby reducing power consumption and cost. Also, the use of lower power would reduce the likelihood of interference with nearby cells thereby aiding best use of network resources to maximise traffic capacity.

Additionally, a frequency which would not ordinarily be used at the edge of a cell coverage area because of interference, could be used in a smaller area near the base station.

It may also be advantageous to other enterprises such as retailers for example, to encourage subscribers to use their mobile stations in a particular location, eg one of their shops or stores. In such a case, under some appropriate subsidy agreement between the retailer and the network operator, favourable, cheap call rates could be offered to the subscriber whenever he used his mobile station in the retailer's store, thereby attracting customers into the store.

In addition to the cheaper rate on offer, there is a further advantage to the subscriber in that if the mobile station is close enough to a base station so that transmitted power is kept low, then the battery life of the mobile station is extended.

Therefore, a means for billing cellular 'phone calls based on subscriber location relative to a base station is proposed.

Accordingly, the invention comprises; a cellular radi ocommunication system including a mobile station and a base station for providing radiocommunication services between the mobile station and a telephone network, and further including means for measuring the distance between the mobile station and the base station, and means for calculating a call charge dependant upon the value of the measured distance.

The means for measuring the distance between the mobile station and the base station may involve measuring the time that a test signal takes to travel between the mobile station and the base station. Alternatively, the distance measurement may involve a measure of the power received by the mobile station from the base station.

The invention, thus provides a means for billing calls dependant upon the proximity of the mobile station to the base station.

Means may also be provided for informing the subscriber that he is in a cheap call rate zone.

Some embodiments of the invention will now be described, by way of example only, with reference to the drawings of which: Figures 1 and 2 are schematic diagrams of the network components of a cellular radio communication system in accordance with the invention, and Figure 3 is a schematic block diagram of components comprising a mobile station and base station included in Figure 2.

With reference to Figure 2, a base station 8 and its associated antenna 9 serve a cell 10 and communicate with a MSC 11 which in turn is linked to a CBC 12. An area 13 defined and enclosed by circle 14 is designated as a cheap rate area and could, for example, be co-located with a shopping mall.

A call made from any location within the area 13 (and therefore, at a point within a maximum distance from the base station 8 equal to the radius of the circle 14) attracts a cheaper rate than does a call outside the area 13.

A mobile station 15 is shown inside the area 13 and is adapted to communicate with the base station 8. A call is set up between the MSC 11 and the mobile station 15 via the base station 8 in the usual manner, an example of which is described in detail in the aforementioned book on GSM. Call set up procedure includes a measurement of the received RF power from the base station, the measurement being performed by circuitry incorporated in the mobile station. Conventionally, this circuitry monitors the received power and reports its level to the base station for the purpose of allowing the base station to adjust both uplink and downlink levels. Additionally and in accordance with the invention, the received power measurement is used to calculate the distance between the base station 8 and the mobile station 15.

With reference to Figure 3, the base station 8 includes transmit circuitry 16 and receive circuitry 17 connected to antenna 9 via a duplexer 18 in the usual manner. The base station 8 also includes a comparator 19 connected to the outputs of the transmit circuitry 16 and received circuitry 17. The output of the comparator 19 is fed into a compute distance block 20.

The mobile station 15 of Figure 3 includes an antenna 21 connected to transmit circuitry 22 and receive circuitry 23 via a duplxer 24. The receive circuitry 23 includes a received signal strength indicator (RSSI) 25 whose output is connected to the transmit circuitry 22. The illustrated components of the mobile station 15 all operate in a conventional manner.

In use and when a communications link has initially been established between the base station 8 and the mobile station 15, the RSSI 25 measures the level of the power received. The mobile station 15 transmits information relating to the level of the power received as measured by the RSSI 25, back to the base station 8.

At the base station 8, the comparator 19 compares the value of the power which has been measured by the RSSI 25 with the power level of its original transmission (which is known by the transmit circuitry 16) and outputs the results of its comparison to the compute distance block 20.

The difference in power level is a function of the distance between a mobile station 15 and the base station 8 and, knowing atmospheric attenuation characteristics, this is computed in the compute distance block 20 which further determines whether or not the computed distance lies within the cheap call rate loan. If the distance is within the cheap call rate loan, the compute distance block 20 signals this fact to the transmit circuitry 16 which in turn generates an appropriate signal for transmission over a broadcast channel to the mobile station 15. This call rate information can then be displayed on the mobile station display screen (not shown). Means for displaying messages on a mobile station screen are well known.

The CBC 12 (see Figure 2) is notified of the call rate via the MSC 11 and the subscriber is billed accordingly.

In an alternative embodiment, the distance computation is performed within the mobile station 15 rather than the base station 8. In this case, the base station needs to tell the mobile station what the level of the transmitted power is, so that the mobile station 15 can make its comparison. Then the mobile station 15 tells the base station 8 if it is entitled to a cheap call rate. This information is then relayed by the base station to the charge and billing centre.

Similarly, the power measurement could be based on the received power level of the broadcast control channel so the mobile station could display charging information during idle mode. This process could operate in the SIM card.

Claims

CLAIMS 1. A cellular radio communication system including: a mobile station and a base station for providing radio communication services between the mobile station and a telephone network, and further including means for measuring the distance between the mobile station and the base station, and means for calculating a call charge dependant on the value of the measured distance.
2. A cellular radio communication system as claimed in Claim 1 in which the means for measuring the distance between the mobile station and the base station includes means for comparing the strength of a signal transmitted from the base station with the strength of the signal as received at the mobile station.
3. A cellular radio communication system as claimed in Claim 1 or 2 in which the means for measuring said distance is incorporated in the base station.
4. A cellular radio communication system as claimed in Claim 1 or Claim 2 in which the means for measuring said distance is incorporated in the mobile station.
5. A method of billing calls made in a cellular radio communications network in which calls made from a location within a predetermined distance from a base station are billed at a predetermined rate, including the steps of: transmitting a signal of known strength from the base station to a mobile station, computing the distance between the base station and the mobile station by comparing the strength of the signal as received at the mobile station with the strength of the signal as transmitted from the base station, and determining whether the distance computed is less than the predetermined distance.
6. A method as claimed in Claim 5 and further including the step of: informing the mobile station that calls are billed at a predetermined rate.
7. A cellular radio communication system substantially as hereinbefore described with reference to Figure 3.
8. A method of billing calls made in a cellular radio communications network substantially as hereinbefore described with reference to Figures 2 and 3.