Method and arrangement for transferring special cell information in a cellular system

• US 6,532,363 B1
• Filed: 03/08/2000
• Issued: 03/11/2003
• Est. Priority Date: 09/10/1997
• Status: Expired due to Fees

• Current Assignee: Nokia Mobile Phones UK Limited (Nokia Corporation)
• Original Assignee: Nokia Mobile Phones UK Limited (Nokia Corporation)
• Inventors: Pussinen, Arto
• Primary Examiner(s): Maung, Nay
• Assistant Examiner(s): LELE, TANMAY S
• Application Number:
  US09/508,212
• Time in Patent Office: 1,098 Days
• Field of Search: 455/432, 455/435, 455/436, 455/440, 455/443, 455/445, 455/446, 455/448, 455/485
• US Class Current: 455/435.1
• CPC Class Codes: H04W 36/0061 of neighbour cell information

Abstract

The invention relates to a method for transferring special cell information in a communications system and a cellular system and mobile station realizing the method. The invention can be advantageously applied to cellular systems specifying cell-specific services for users, such as cell-dependent charging. An idea of the invention is that special cell identities are transferred from a mobile station to a base station system in coded form (521, 522) in such a manner that the transfer of special cell identity information uses fewer bits than what would be needed for the transfer of special cell identities as such. Cell identities are advantageously chosen such that the cell identities of a single area can be coded using a small number of bits. In accordance with the above-mentioned principle according to the invention the transfer can be carried out advantageously in such a manner that the first special cell identity in the special cell list is transferred as such (501) whereafter it is transferred transfer codes (522) which are differences (521) of two consecutive special cell identities in the special cell list. The special cell identities in the special cell list are advantageously arranged in the order of magnitude in the special cell list. Using the solution according to the invention it is possible to transfer the special cell information on the radio path by means of a single short message so that the transfer of special cell information can be carried out quickly without using a lot of the radio path'"'"'s capacity in connection with call setup and handover.

Claims

1. A method for transferring special cell information in a cellular system from a mobile station to a base station system so that said special cell information comprises a first special cell identity and a second special cell identity, and a transfer code is created which is transferred from the mobile station to the base station system (532) and the second special cell corresponding to the second special cell identity is identified on the basis of a transfer code (611), characterised in that the said transfer code is created based on at least the first and second special cell identity (521, 522) in such a way that the length of the said transfer code is shorter than the length of the second special cell identity.

2. The method of claim 1, characterised in that said special cell information is transferred in order to control the selection of active base station.

3. The metod of claim 1, characterised in that said cellular system substantially is a GSM system.

4. The method of claim 1, characterised in that the transfer of information of two special cells comprises the following steps:

a first special cell identity is transferred (501, 602),

a transfer code is defined as the difference of a second special cell identity and first special cell identity (521, 522),

the transfer code thus created is transferred (602) and

the sum of the first special cell identity transferred and the transfer code transferred is calculated in order to create a second special cell identity (611).

5. The method of claim 4, characterised in that a data field of a predetermined length is reserved for the transfer code to be transferred.

6. The method of claim 5, characterised in that when the value of the difference exceeds the predetermined data field length, one or more zero values are transmitted (522) so that each zero value is considered to increment the value of the difference represented by the transfer code by an amount which equals the maximum transfer code value plus one.

7. The method of claim 1, characterised in that a special cell message is transferred from a mobile station to a base station system, said message containing at least the following information:

message type,

message length,

the first cell identity (CI1) in the special cell list,

transfer codes corresponding to the next cell identities (CI2, CI3, . . . ) in the special cell list, and

local area codes (LAC) of the special cells (CI) that belong to the current local service area (LSA).

8. The method of claim 7, characterised in that the special cell message comprises a specification field indicating the length of the transfer code.

9. The method of claim 8, characterised in that said specification field may adopt a special value so that the field after said specification field indicates the number of the special cell identities the values of which immediately follow the value of the first special cell identity in the special cell list.

10. The method of claim 7, characterised in that the special cell message is transferred in conjunction with call setup or in a message transferred in connection with a handover.

11. A cellular system comprising means for selecting a serving base station on the basis of a special cell list which said cellular system comprises means (701-704, 721-723, 750-752) for transferring special cell information from a mobile station to a base station system where upon the said special cell information comprises at least a first special cell identity and a second special cell identity and means for identifying the second special cell corresponding to the second special cell identity on the basis of a transfer code, characterised in that said cellular system comprises means for creating the said transfer code at least on the basis of the said first special cell identity and on the said second special cell identity so that the length of the said transfer code is shorter than the length of the second special cell identity.

12. The cellular system of claim 11, characterised in that said cellular system substantially is a GSM system.

13. A mobile station (700) connected with a cellular system comprising means (704) for storing and sending special cell information to the base station system where the said special cell information comprises a first special cell identity and a second special cell identity and means for creating and sending a transfer code to the base station system for identifying the second special cell corresponding to the second special cell identity, characterised in that the mobile station also comprises means for creating the said transfer code on the basis of the said first and second special cell identity so that the length of the said transfer code is shorter than the length of the second special cell identity.

14. The mobile station of claim 13, characterised in that said cellular system substantially is a GSM system.