Method and apparatus for broadcasting system information in a cellular communications network

• US 6,628,946 B1
• Filed: 05/18/2000
• Issued: 09/30/2003
• Est. Priority Date: 05/20/1999
• Status: Expired due to Term

• Current Assignee: Optis Cellular Technology LLC (Brevet Capital)
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Wiberg, Niclas, Rimhagen, Thomas
• Primary Examiner(s): Maung, Nay
• Assistant Examiner(s): TRINH, TAN H
• Application Number:
  US09/572,846
• Time in Patent Office: 1,230 Days
• Field of Search: 455/432, 455/434, 455/435, 455/445, 455/62, 455/343, 455/33.1, 370/347, 370/331
• US Class Current: 455/434
• CPC Class Codes: H04W 48/12 using downlink control channel
• CPC Class Codes: H04W 8/18 Processing of user or subscriber data, e.g. subscribed services, user preferences or user profiles; Transfer of user or subscriber data
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

In a cellular telecommunications system or network, tags are associated with one or more system control parameters. For example, a given tag value may be indicative of particular values for one or more system information parameters. In each cell, a base station (BS) transmits or broadcasts currently valid tag values. System information blocks including the system information parameters themselves (which correspond to particular tag(s)) are also broadcast by base stations. A mobile station receiving a valid tag value from a base station determines whether or not it has to read system information block(s) corresponding to that tag value depending upon whether the base station has already stored or cached such block(s) corresponding to the tag value. As will be appreciated by those skilled in the art, different embodiments of the instant invention may result in the mobile station not having to re-read identical system information each time it changes cells, or while moving in the same cell. This may conserve radio resources and reduce battery consumption, thereby improving standby time of the mobile station.

Claims

1. A method of transmitting control information in a cellular telecommunications network including a first base station in a first cell and a second base station in a second cell, the method comprising:

transmitting first control information and second control information from the second base station in the second cell; and

upon making a cell change by entering the second cell from the first cell and reading the first control information transmitted from the second base station in the second cell, the mobile station determining whether or not to read the second control information based upon analysis by the mobile station of the first control information read by the mobile station, so that the mobile station can use the second control information in the second cell without having to read the second control information from the second base station in the second cell when the mobile station determines that the mobile station is already storing the second control information that it received in another or previous cell.

2. The method of claim 1, wherein the first control information comprises at least one tag value that is valid in the second cell, and the second control information comprises at least one system information parameter value that corresponds to the valid tag value.

3. The method of claim 2, wherein the first control information further comprises a header block including the at least one tag value that is valid in the second cell, a network identifier, and a cell identifier.

4. The method of claim 3, wherein the first control information is transmitted on a first channel and the second control information is transmitted on a second channel different than the first channel, and wherein the first control information further comprises an identity of the second channel on which the second control information is to be transmitted.

5. The method of claim 3, wherein the first control information further comprises first, second, and third tag values that are valid in a cell in which the mobile station is located and identities of multiple channels on which system information blocks which correspond to the tag values are to be transmitted.

6. The method of claim 2, wherein the second control information includes a tag value that is valid in each of the first and second cells, and system information parameter values that correspond to the tag value.

7. The method of claim 6, wherein the second control information includes an expiration time for a control block including the system information parameter values that correspond to the tag value.

8. The method of claim 1, further comprising the second base station located in the second cell and transmitting control information relating to a third cell neighboring the second cell.

9. The method of claim 1, wherein the second control information includes an expiration time for a control block including system information parameters.

10. A method of utilizing control information transmitted in a cellular telecommunications network from a base station to a mobile station, the method comprising:

transmitting first control information and second control information from the base station; and

upon making a cell change and reading the first control information from the base station in a new cell, the mobile station determining whether or not to read the second control information based upon analysis of the first control information, so that the mobile station need not read the second control information in the new cell if the mobile station determines that the mobile station is already storing the second control information that it received in a previous cell, so that the mobile station can use the second control information in the new cell without having to read the second control information from the base station in the new cell when the mobile station determines that the mobile station is already storing the second control information that it received in another cell.

11. The method of claim 10, wherein the first control information comprises at least one tag value that is valid in the new cell, and the second control information comprises at least one system information parameter value that corresponds to the valid tag value;

and wherein the first control information and the second control information are transmitted on the same control channel.

12. The method of claim 11, further comprising the steps of:

the mobile station reading the tag value upon entry into the new cell;

the mobile station analyzing the tag value by determining whether or not the mobile station has stored or cached system information parameter value(s) corresponding to the tag value; and

the mobile station determining whether or not to read the second control information based upon whether the mobile station has stored or cached system information parameter value(s) corresponding to the tag value.

13. A method of utilizing control information in a cellular telecommunications network including first and second cells in which first and second base stations are located, respectively, the method comprising:

when in a first cell, the mobile station receiving a tag value and system information parameter values corresponding to the tag value from the first base station;

the mobile station moving from the first cell into the second cell; and

when in the second cell, the mobile station receiving a tag value from the second base station and determining whether the tag value received by the mobile station from the second base station corresponds to a tag value stored by the mobile station, and if so the mobile station utilizing the system information parameter values corresponding to the stored tag value without having to re-read the system information parameters in the second cell, so that the mobile station can use the system information parameters in the second cell without having to read the parameters from the second base station in the second cell when the mobile station determines that the mobile station is already storing the parameters that it received in another previous cell.

14. A network comprising:

a mobile station;

a base station that transmits first control information and second control information; and

wherein the mobile station determines, upon making a cell change into a new cell in which the base station is located and reading the first control information from the base station, whether or not to read the second control information based upon analysis of the first control information, so that the mobile station may use the second control information in the new cell without having to read the second control information from the base station in the new cell if the mobile station determines that the mobile station is already storing the second control information.

15. The network of claim 14, wherein the first control information and the second control information are transmitted by the base station to the mobile station on different control channels.

16. The network of claim 14, wherein the first control information comprises at least one tag value that is valid in the new cell, and the second control information comprises at least one system information parameter value that corresponds to the valid tag value.

17. The network of claim 16, wherein the mobile station reads the tag value upon entry into the new cell and determines whether or not the mobile station has stored or cached system information parameter value(s) corresponding to the tag value, and wherein the mobile station determines whether or not to read the second control information from the base station in the new cell based upon whether the mobile station has stored or cached system information parameter value(s) corresponding to the tag value.

18. A method of using control information transmitted from a base station to a mobile station in a cellular telecommunications network, the method comprising the steps of:

transmitting control information including at least one system information parameter value along with an expiration time to the mobile station;

the mobile station receiving and using the control information; and

the mobile station not using the control information after the expiration time has expired.

19. The method of claim 18, further comprising the steps of:

the base station transmitting a list of tag values that are valid in a cell in which the base station is provided; and

wherein the system information parameter value corresponds to at least one of the tag values that is valid in the cell in which the base station and mobile station are located.

20. A cellular telecommunications network comprising:

a mobile station and a base station each located in a cell;

wherein the base station transmits control information including at least one system information parameter value along with an expiration time; and

wherein the mobile station receives the control information from the base station and determines whether to use the system information parameter value based at least in part upon whether the expiration time has expired.

21. A method of transmitting control information to a mobile station in a first cell of a cellular telecommunications network, the method comprising:

a first base station transmitting control information to the mobile station in the first cell indicating to the mobile station that the control information is not valid in the first cell but is valid in a second cell.

22. The method of claim 21, further comprising the steps of:

the mobile station storing in memory the control information;

the mobile station moving into a second cell which neighbors the first cell; and

the mobile station using the control information in the second cell without having to read the control information from a second base station in the second cell, because the mobile station had previously stored the control information.

23. A cellular telecommunications network comprising:

a first base station in a first cell;

a second base station in a second cell;

a mobile station moveable between the first and second cells; and

wherein the first base station transmits first control information to the mobile station in the first cell including information indicating that the first control information is valid in the second cell but not in the first cell in which the first base station is located.

24. The network of claim 23, wherein:

the mobile station includes a memory for storing the first control information; and

wherein when the mobile station moves into the second cell from the first cell the mobile station uses the first control information in the second cell without having to read the first control information from the second base station in the second cell.

25. The network of claim 24, wherein the first base station further transmits second control information to the mobile station in the first cell that is valid in the first cell and indicates to the mobile station that the second control information is valid in the first cell.

26. The network of claim 25, wherein the first base station transmits the first control information at a smaller repetition interval than the second control information.

27. A block of control information to be transmitted to a mobile station in a cellular telecommunications network, the block comprising:

system information parameter values that are valid in a particular cell of the cellular telecommunications network; and

an expiration time after which the system information parameter values are not to be used by mobile stations in the network.

28. The block of claim 27, further comprising a block type field specifying what system information parameters are in the block and an area in which the block may be used.

29. The block of claim 27, further comprising a value tag field indicative of at least one tag value that is valid in said cell of the network.

30. A method of dividing a cellular telecommunications network into a plurality of different areas, the method comprising:

providing a plurality of cells in the cellular telecommunications network, each cell including a base station;

dividing the network in a first manner into a plurality of different cell areas, first and second ones of the cell areas not overlapping with one another and each including two or more of the plurality of cells;

all cells in the first cell area sharing system information, and all cells in the second cell area sharing system information;

broadcasting information to mobile stations indicative of the sharing of system information parameters by cells in the first and second cell areas; and

dynamically changing system information parameters that are shared by the cells in the first cell area, and dynamically changing system information parameters that are shared by the cells in the second cell area, at respective points in time after the network has been installed and operational.

31. The method of claim 30, wherein all cells in the first cell area share a first common tag value that is indicative of a plurality of system information parameter values, and all cells in the second cell area share a second common tag value that is indicative of a plurality of system information parameter values.

32. The method of claim 30, further comprising, following said dividing step, re-dividing the network in a second manner that is different than the first manner, into a plurality of different new cell areas, first and second ones of the new cell areas not overlapping with one another and each including two or more of the plurality of cells;

all cells in the first new cell area sharing system information, and all cells in the second new cell area sharing system information; and

broadcasting information to mobile stations indicative of the sharing of system information parameters by cells in the first and second new cell areas.