AU731611B2

AU731611B2 - Method for transmitting tags in a cellular system

Info

Publication number: AU731611B2
Application number: AU42402/99A
Authority: AU
Inventors: Chan-Bok Lee
Original assignee: Samsung Electronics Co Ltd
Current assignee: Samsung Electronics Co Ltd
Priority date: 1998-08-19
Filing date: 1999-07-30
Publication date: 2001-04-05
Anticipated expiration: 2019-07-30
Also published as: KR100270657B1; AU4240299A; CN1250340A; KR20000014248A

Description

P/00/011 28/5/91 Regulation 3.2

AUSTRALIA

Patents Act 1990

ORIGINAL

COMPLETE SPECIFICATION STANDARD PATENT Name of Applicant: Actual Inventor Address for service is: Samsung Electronics Co, Ltd Chan-bok Lee WRAY ASSOCIATES 239 Adelaide Terrace Perth, WA 6000 Attorney code: WR Invention Title: "Method For Transmitting Tags In A Cellular System" The following statement is a full description of this invention, including the best method of performing it known to me:- I c~ -2-

TITLE

Method For Transmitting Tags In A Cellular System FIELD OF THE INVENTION This invention relates to a method for transmitting tags in a cellular system, and in particular to a method for transmitting tags in a cellular system to reduce the burden of tracking tags in base stations.

BACKGROUND ART A cellular mobile communication system divides a coverage region into a plurality of cells each of which has a base station. The base stations are controlled by a switching centre to co-ordinate handoffs between base stations as a subscriber moves from cell to cell.

Figure 1 shows a block diagram of a code division multiple access (CDMA) cellular system. The cellular system comprises base stations (BS) 20, 30 and providing communication services to a mobile telephone (MT) 10, and a mobile switching centre (MSC) 50 connecting the base stations to a public switched telephone network (PSTN) :When the MSC 50 is requested to establish a call to a subscriber of another system or base station, the MSC 50 sends a message to the MT 10 via a base station. The base station transmits a call message to the MT using a paging channel. The MT transmits a response message to the base station through an access channel in the cellular system. When the base station receives the response message from the MT, the base station transmits the received message to the MSC. When the MSC receives the response message it establishes a call to the MT by allocating a traffic channel of the base station to the MT.

When the MSC receives a response message from the base station, it must distinguish which MT the response message relates to amongst the plurality of MTs in its area. To achieve this, the MSC uses a key, referred to as a "tag". The nominal form of the tag is defined in IS-634.

Figure 2 is a block diagram illustrating the method of transmitting tags used in prior art CDMA cellular systems. At step s110, the MSC 50 transmits a call request message to the BS 20. The call request message includes a tag and the mobile identity (MID) of the MT for which it is required to make a call.

At step s120 the BS 20 starts a timer for the tag. The BS 20 also stores the tag and the MID in a table that is similar to a call information table stored in the MSC.

Next, the BS 20 transmits a call request message including the MID at step s130.

In the next step s140, the MT 10 receives the call request message and transmits a call response message which also includes its MID.

Upon receipt of the call response message from the MT 10, the BS 20 searches the table for the MID contained in the received call response message at step s150. If the MID is found in the table, the base station cancels the timer. Next, at step s160, the BS 20 transmits a call response message including the tag to the MSC 50, which then establishes a call to the MT If a timer expires before a call response message is received by the BS 20 from a MT 10, the BS 20 judges that the call is a failure.

**By using tags, the MSC eliminates the need to search its call information table.

However, in the prior art method described above, the base station makes a i table similar to the call information table of the MSC. The base station has the burden of searching its table for the MID whenever a call response message is received. Thus, the base station is burdened with controlling the timer and managing and searching the table. This unnecessary duplication of resources occurs throughout the cellular system.

A general system using tags to distinguish subjects is disclosed in US Patent 5,804,810 titled "Communicating With Electronic Tags". US Patent 5,804,810 describes monitoring a group of objects using two electronic tags, each attached to an object in the group. Each tag has circuitry for communicating information relating to an object in the group to a second tag. Each tag also includes a -4memory connected to the circuitry that is capable of storing information and a controller connected to the memory and the circuitry.

DISCLOSURE OF THE INVENTION Throughout the specification, unless the context requires otherwi'e, the word "comprise" or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.

In accordance with a first aspect of this invention, there is provided a method for transmitting tags in a cellular system having a plurality base stations providing telecommunication services to mobile telephones in a specific area, and mobile switching centers for connecting said base stations to subscribers of other systems or other base stations, said method comprising the steps of: transmitting a first request message including a tag from the mobile switching center to a base station; transmitting a second request message from the base station to a base station upon receipt of said first request message by the base station, wherein the second request message includes the tag contained in the first request message; transmitting a first response message from a mobile telephone to the base 0020 station upon receipt of said second request message by the mobile i0° station, wherein the first response message includes the tag contained in the second request message; transmitting a second response message from the base station to the mobile switching centre upon receipt of said first response message by 25 the base station, wherein the second response message includes the tag contained in the first response message; and receiving said second response message at the mobile switching centre and using the tag contained in the received second response message to search a call information table.

In accordance with a second aspect of this invention, there is provided a method for transmitting tags in a cellular system having a plurality base stations providing telecommunication services to mobile telephones in a specific area, and mobile switching centers for connecting said base stations to subscribers of other systems or other base stations, said method comprising the steps of: transmitting a first request message from said mobile switching center to a base station; and if said first request message includes a tag, inserting said tag into a second request message and transmitting the second request message from the base station to a mobile telephone.

Preferably, the method further comprises the step of transmitting a first response S* 15 message from a mobile telephone to the base station upon receipt of said second request message by the mobile station, wherein if said second request message includes a tag, said tag is inserted into the first response message.

In accordance with a third aspect of this invention, there is provided a method for transmitting tags in a cellular system having a plurality base stations providing 20 telecommunication services to mobile telephones in a specific area, and mobile switching centers for connecting said base stations to subscribers of other V" systems or other base stations, said method comprising the steps of: transmitting a request message from a base station to a mobile telephone; and if said request message includes a tag, inserting said tag into a response message by the mobile station and transmitting the response message to the base station.

-6- In accordance with a fourth aspect of this invention, there is provided a method for transmitting tags in a cellular system having a plurality base stations providing telecommunication services to mobile telephones in a specific area, and mobile switching centers for connecting said base stations to subscribers of other systems or other base stations, said method comprising the steps of: receiving a request to establish a call from other systems or subscribers of other base stations at the mobile switching center; transmitting a first request message including a tag from the mobile switching center to a base station; transmitting a second request message from the base station to a base station upon receipt of said first request message by the base station, wherein the second request message includes the tag contained in the first request message; transmitting a first response message from a mobile telephone to the base 15 station upon receipt of said second request message by the mobile station, wherein the first response message includes the tag contained in the second request message; transmitting a second response message from the base station to the S. mobile switching centre upon receipt of said first response message by 20 the base station, wherein the second response message includes the tag contained in the first response message; and receiving said second response message at the mobile switching centre and using the tag contained in the received second response message to ~search a call information table.

BRIEF DESCRIPTION OF THE DRAWINGS One embodiment of this invention will now be described with reference to the accompanying drawings, in which: -7- Fig.1 is a block diagram of a code division multiple access (CDMA) cellular system; Fig. 2 is a message flow diagram of a prior art method for transmitting tags; and Fig. 3 is a message flow diagram of a method for transmitting tags according to a preferred embodiment of this invention.

DETAILED DESCRIPTION OF THE BEST MODE(S) The embodiment will be described with reference to the CDMA cellular system shown in Fig. 1.

When tags are used in the interface between the MSC and a base station and tags are not used in the interface between the base station and a MT, the base station has to perform management of the tags. To reduce the management of tags the base station must perform, the embodiment adds tags to the interface between the base station and the MT, as described in more detail below.

The MSC sends a request message to a mobile telephone via a base station.

15 The request message instructs the mobile telephone to reply with a special response message. The MSC analyses the tag included in the received response message to determine the mobile telephone that the response message corresponds to.

.If the base station receives a first message including a tag from the MSC, the base station inserts the tag in a second message sent by the base station to the MT. If the MT receives the second message including the tag from the base station, the MT inserts the received tag into a response message sent from the mobile station to the base station. Because the MT is the terminal the message is addressed to, it is not necessary for the MT to make a table and manage the tag. Instead, the MT re-transmits the received tag as part of a first response message. Upon receipt of the first response message, the base station transmits the received tag to the MSC as part of a second response message. By using this method, it is not necessary for the base station to make a table or manage -8the tags. As described below, the MSC assumes responsibility for managing a timer for the message, so the base station doesn't manage the timer either.

The embodiment can be applied to a request message transmitted to the MT and the associated response message, including messages sent through the paging channel. For example, in case of IS-95, there are general page messages, data burst messages, authentication challenge messages, order messages, feature notification messages and status request messages.

Because the load caused by a call request message in the cellular system is great, the following description explains the operation of the embodiment in the case of a call message. It should be appreciated that the invention isn't limited to use in relation to call messages.

Fig. 3 is a message flow diagram of the method according to the embodiment in the case of a call request message.

When the MSC 50 receives a request to establish a call to a subscriber of S.i 15 another system or other base station, the MSC 50 searches the information on the MT 10 requesting a call and makes a call information table of data needed to establishing the call. The MSC 50 searches for the position of the MT 10 and finds the base station that currently receives a signal from the MT In step s210, the MSC 50 transmits a call request message to the found base 20 station. To enable to MSC 50 to identify the MT 10 and the corresponding call information table when a response is received, the call request message includes a key value (or tag) corresponding to the call information table. The MSC 50 also starts a timer for the message. The call request message also includes the mobile identity (MID) of the MT S 25 In step s220, the base station 20 transmits the tag and the MID included in call request message received from the MSC 50 in a further call request message transmitted by the base station to the MT 10. Because the tag is transmitted to the mobile station and a timer for the call request message has already started in the MSC 50, the base station doesn't make a table of tags and MIDs. That is, the base station's involvement with the tag received from the MSC 50 is to transmit it to the MT 10 as a part of the further call request message. The base station doesn't store any information concerning the tag and doesn't wait for a response from the MT In step s230, the MT 10 receives the further call request message from the base station 20 and transmits a call response message to the base station. The MT includes the tag received from the base station 20 in the call response message sent to the base station In step s240, the base station 20 receives the call response message from the MT 10 and transmits a further call response message to the MSC 50. The base station 20 includes the tag received from the MT10 in the further call response message transmitted to the MSC The MSC 50 receives the further call response message from the base station which includes the tag. The MSC 50 then searches for a call information table corresponding to the tag included in the further call response message. If a 15 call information table is found, the MSC 50 removes the timer. The MSC 50 then allocates a traffic channel in the base station 20 to the MT 10 and stores this information in the call information table.

As described above, the method of the embodiment reduces the load on the base station and removes unnecessary operations. The embodiment can be applied generally to request messages transmitted to the MT 10 and the response message received from it through the paging channel. If a tag is included in the message received from the MSC 50, the base station includes the tag in the message transmitted to the MSC While the invention is susceptible to various modification and alternative forms, 25 specific embodiments thereof have been shown by way of example in the drawings and detected description. It should be understood, however, that the present invention is not limited to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternative falling within the spirit and scope of the invention as defined by the appended claims.

Claims

1. A method for transmitting tags in a cellular system having a plurality base stations providing telecommunication services to mobile telephones in a specific area, and mobile switching centers for connecting said base stations to subscribers of other systems or other base stations, said method comprising the steps of: transmitting a first request message including a tag from the mobile switching center to a base station; transmitting a second request message from the base station to a base station upon receipt of said first request message by the base station, wherein the second request message includes the tag contained in the first request message; transmitting a first response message from a mobile telephone to the base station upon receipt of said second request message by the mobile 15 station, wherein the first response message includes the tag contained in the second request message; transmitting a second response message from the base station to the mobile switching centre upon receipt of said first response message by the base station, wherein the second response message includes the tag 20 contained in the first response message; and receiving said second response message at the mobile switching centre and using the tag contained in the received second response message to search a call information table.

A method for transmitting tags in a cellular system having a plurality base stations providing telecommunication services to mobile telephones in a specific area, and mobile switching centers for connecting said base stations to subscribers of other systems or other base stations, said method comprising the steps of: -11 transmitting a first request message from said mobile switching center to a base station; and if said first request message includes a tag, inserting said tag into a second request message and transmitting the second request message from the base station to a mobile telephone.

3. The method of claim 2, further comprising the step of transmitting a first response message from a mobile telephone to the base station upon receipt of said second request message by the mobile station, wherein if said second request message includes a tag, said tag is inserted into the first response message.

4. A method for transmitting tags in a cellular system having a plurality base stations providing telecommunication services to mobile telephones in a specific area, and mobile switching centers for connecting said base stations to subscribers of other systems or other base stations, said method 15 comprising the steps of: g* transmitting a request message from a base station to a mobile telephone; o and if said request message includes a tag, inserting said tag into a response message by the mobile station and transmitting the response message to 20 the base station.

5. A method for transmitting tags in a cellular system having a plurality base S. stations providing telecommunication services to mobile telephones in a specific area, and mobile switching centers for connecting said base stations to subscribers of other systems or other base stations, said method S 25 comprising the steps of: receiving a request to establish a call from other systems or subscribers of other base stations at the mobile switching center; -12- transmitting a first request message including a tag from the mobile switching center to a base station; transmitting a second request message from the base station to a base station upon receipt of said first request message by the base station, wherein the second request message includes the tag contained in the first request message; transmitting a first response message from a mobile telephone to the base station upon receipt of said second request message by the mobile station, wherein the first response message includes the tag contained in the second request message; transmitting a second response message from the base station to the mobile switching centre upon receipt of said first response message by the base station, wherein the second response message includes the tag contained in the first response message; and receiving said second response message at the mobile switching centre and using the tag contained in the received second response message to e search a call information table.

6. A method for transmitting tags in a cellular system substantially as described herein with reference to Fig. 3 of the accompanying drawings. o* Dated this Thirtieth day of July 1999. Samsung Electronics Co, Ltd Applicant Wray Associates Perth, Western Australia Patent Attorneys for the Applicant