Eliminating multicast/broadcast collisions in a wireless local area network

• US 7,385,945 B1
• Filed: 08/04/2004
• Issued: 06/10/2008
• Est. Priority Date: 08/04/2004
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Devalla, Sreenivas, Olson, Timothy S.
• Primary Examiner(s): Yao; Kwang Bin
• Assistant Examiner(s): Lu; Xiao Qin (Vincent)
• Application Number:
  US10/912,595
• Time in Patent Office: 1,406 Days
• Field of Search: 370/328, 370/445, 370/447, 370/461, 370/462
• US Class Current: 370/328
• CPC Class Codes: H04W 72/30 Resource management for broadcast services
• CPC Class Codes: H04W 74/08 Non-scheduled access, e.g. ALOHA hybrid access H04W74/02

Abstract

In an access point operating in a wireless local area network, a method is disclosed for assisting a radio manager to manage a radio environment without location information. By performing radio discovery to receive beacon signals from neighboring access points, an initial configuration of a radio environment is generated based on the received beacon signals. Measurements are received from a client device that performs measurements by a user walking through a desired coverage area while operating the client device and the radio configuration is adjusted based on the received measurements.

Claims

1. In a wireless local area network, a method for preventing simultaneous transmission of packets by neighboring access point devices, the method comprising:

directing a plurality of access point devices to transmit signals at a specified power setting on a common channel;

measuring resulting signal strengths of the access point devices broadcasting signals on the common channel at the specified power setting;

calculating path loss information between access point devices in the plurality and between a client device and its respective access point in the plurality;

using the calculated path loss information to determine access points in the plurality that transmit signals at the same time; and

directing at least one of the determined access point devices to change its signal transmission interval.

2. The method of claim 1, wherein the signal transmission interval comprises a beacon signal interval.

3. The method of claim 1, wherein directing the plurality of access point devices to transmit signals at a specified power setting on a common channel and measuring resulting signal strengths is repeated at different power settings.

4. The method of claim 1, wherein using the calculated path loss information to determine access points in the plurality that transmit signals at the same time comprises identifying access points that are configured to transmit on the same channel.

5. The method of claim 1, wherein using the calculated path loss information to determine access points in the plurality that transmit signals at the same time comprises identifying received signal strength at each access point that is less than a minimum receive strength.

6. The method of claim 1, wherein using the calculated path loss information to determine access points in the plurality that transmit signals at the same time comprises identifying a wireless access location where received signal strength from multiple access points is greater than a minimum receive sensitivity.

7. The method of claim 6, wherein using the calculated path loss information to determine access points in the plurality that transmit signals at the same time comprises identifying, at the wireless access location, a difference between received signal strengths from a plurality access points is less than a required signal to noise ratio for data rates at which the plurality of access points transmitted the signals.

8. A computer readable medium containing instructions, which, when executed by a computer, prevent simultaneous transmission of packets by neighboring access point devices in a wireless network, by:

directing a plurality of access point devices to transmit signals at a specified power setting on a common channel;

measuring resulting signal strengths of the access point devices broadcasting signals on the common channel at the specified power setting;

calculating path loss information between access point devices in the plurality and between a client device and its respective access point in the plurality;

using the calculated path loss information to determine access points in the plurality that transmit signals at the same time; and

directing at least one of the determined access point devices to change its signal transmission interval.

9. The computer readable medium of claim 8, wherein the signal transmission interval comprises a beacon signal interval.

10. The computer readable medium of claim 8, wherein directing the plurality of access point devices to transmit signals at a specified power setting on a common channel and measuring resulting signal strengths is repeated at different power settings.

11. The computer readable medium of claim 8, wherein using the calculated path loss information to determine access points in the plurality that transmit signals at the same time comprises identifying access points that are configured to transmit on the same channel.

12. The computer readable medium of claim 8, wherein using the calculated path loss information to determine access points in the plurality that transmit signals at the same time comprises identifying received signal strength at each access point that is less than a minimum receive strength.

13. The computer readable medium of claim 8, wherein using the calculated path loss information to determine access points in the plurality that transmit signals at the same time comprises identifying a wireless access location where received signal strength from multiple access points is greater than a minimum receive sensitivity.

14. The method of claim 13, wherein using the calculated path loss information to determine access points in the plurality that transmit signals at the same time comprises identifying, at the wireless access location, a difference between received signal strengths from a plurality access points is less than a required signal to noise ratio for data rates at which the plurality of access points transmitted the signals.

15. An apparatus for preventing simultaneous transmission of packets by neighboring access point devices in a wireless network, the apparatus comprising:

a transmitter and a receiver for communicating with a plurality of access point devices;

a processor; and

instructions, which, when executed by the processor;

direct a plurality of access point devices to transmit signals at a specified power setting on a common channel;

measure resulting signal strengths of the access point devices broadcasting signals on the common channel at the specified power setting;

calculate path loss information between access point devices in the plurality and between a client device and its respective access point in the plurality;

use the calculated path loss information to determine access points in the plurality that transmit signals at the same time; and

direct at least one of the determined access point devices to change its signal transmission interval.