Selection of access point in a wireless communication system

• US 7,020,438 B2
• Filed: 01/09/2003
• Issued: 03/28/2006
• Est. Priority Date: 01/09/2003
• Status: Active Grant

• Current Assignee: Nokia Technologies Oy (Nokia Corporation)
• Original Assignee: Nokia Corporation
• Inventors: Sinivaara, Hasse, Väisänen, Ari
• Primary Examiner(s): Hong, Harry S.
• Application Number:
  US10/338,874
• Publication Number:
  US 20040202141A1
• Time in Patent Office: 1,174 Days
• Field of Search: 370/328, 370/329, 370/331, 370/332, 370/338, 455/432.1, 455/434, 455/436, 455/437, 455/450, 455/453, 455/41.2, 709/229
• US Class Current: 455/41.2
• CPC Class Codes: H04B 7/022 Site diversity; Macro-diversity using two or more spaced independent antennas H04B7/04
• CPC Class Codes: H04W 48/20 Selecting an access point

Abstract

The invention relates to a method for selecting an access point in a wireless communication system comprising mobile terminals and access points. To enable the mobile terminals to take into account the prevailing conditions within the entire coverage area of an access point more effectively than before, sets of attributes are sent from mobile terminals to the currently serving access point, each set to contain at least one attribute indicating the quality of a wireless link between the serving access point and the sending mobile terminal. Based on the sets, a service report describing current service conditions in the coverage area of the access point is formed and transmitted to at least one mobile terminal. This terminal examines the service report of at least one access point and, based on the examination, selects the access point to which a wireless link is to be established.

Claims

1. A method for selecting an access point in a wireless communication system comprising mobile terminals and access points, each access point being capable of serving the mobile terminals within a service area of the access point, the method comprising the steps of:

sending at least one set of attributes from a first group of mobile terminals to the access point currently serving said group of mobile terminals, each of said mobile terminals sending a set that contains at least one attribute indicating the quality of a wireless link between the serving access point and the mobile terminal;

based on the sets, forming a service report describing current service conditions in the service area of the access point;

transmitting the service report to a second group of mobile terminals;

in a mobile terminal belonging to said second group, examining at least one service report received; and

in response to the examining step, selecting the access point to which a wireless link is to be established from said mobile terminal.

2. A method according to claim 1, wherein the sets contain the same attributes.

3. A method according to claim 1, wherein the first group contains mobile terminals of a predetermined type.

4. A method according to claim 1, wherein the forming step includes the steps of (a) calculating the average load level of the access point over a preceding time period of a predetermined length and (b) inserting the average load level calculated into the service report.

5. A method according to claim 1, wherein the transmitting step includes broadcasting the service report from the access point.

6. A method according to claim 1, wherein the transmitting step includes sending the service report to a mobile terminal in response to a predetermined request received from said mobile terminal.

7. A method according to claim 1, wherein

the examining step includes the steps of (a) choosing an access point based on at least one predetermined attribute and (b) checking the service report of said access point, and

the selecting step includes selecting said access point if the checking step indicates that the service report is acceptable.

8. A method according to claim 1, wherein said at least one predetermined attribute indicates the level of the signal received from the access point.

9. A method according to claim 2, wherein the forming step includes the steps of (a) calculating averages for at least some of the attributes received in the sets and (b) inserting the averages calculated in the service report.

10. A method according to claim 1, further comprising the step of retrieving the attributes from a management information base within the MAC layer of a mobile terminal belonging to said first group.

11. A method according to claim 1, wherein the forming step includes inserting into the service report information about at least one other access point.

12. A method according to claim 11, wherein said information includes data concerning the wireless links used by said at least one other access point.

13. A method according to claim 3, wherein the mobile terminals belonging to the first group are assigned an identifier by means of which said terminals can be identified from other terminals.

14. A wireless communication system comprising mobile terminals and access points, each access point being capable of serving the mobile terminals within a service area of the access point, the system comprising:

reception means for receiving at least one set of attributes from a first group of mobile terminals, at least one of the attributes to indicate the quality of a wireless link between a particular mobile station and the access point serving said mobile station;

processing means for forming, based on the sets, a service report describing current service conditions in the service area of the access point;

transmission means for transmitting the service report to a second group of mobile terminals; and

in each of the mobile terminals in said second group, (a) examination means for examining a service report received and (b) selection means, responsive to the examination means, for selecting the access point with which a wireless link is to be established.

15. An access point for a wireless communication system, the access point comprising:

interface means for connecting the access point to a distribution system;

a transceiver for communicating wirelessly with mobile terminals located within a service area of the access point, said transceiver being adapted to receive sets of attributes from the mobile terminals, at least one of the attributes to indicate the quality of a wireless link between the serving access point and the respective mobile terminal;

processing means for forming, based on the sets, a service report describing current service conditions in the service area of the access point;

wherein the transceiver is further adapted to transmit the service report to at least one mobile terminal.

16. A mobile terminal for a wireless communication system, the mobile terminal comprising:

a transceiver for communicating with an access point of the wireless communication system via a wireless link;

memory means for storing attributes relating to said link;

collection means for collecting service reports from available access points, each service report describing current service conditions within a service area of a particular access point;

examination means for examining the service report received by the mobile terminal;

selection means, responsive to the examination means, for selecting the access point; and

access means for establishing a wireless link with the access point selected.

17. A mobile terminal according to claim 16, further comprising

data collection means for retrieving predetermined attributes from the memory, at least one of the attributes to indicate the quality of a wireless link between the serving access point and the respective mobile terminal;

wherein the transceiver is adapted to send the retrieved attributes to an access point.

18. A mobile terminal according to claim 16, wherein the mobile terminal is a mobile phone.

19. A mobile terminal according to claim 17, wherein the mobile terminal is a laptop computer.