Method and apparatus for determining alternative second stationary access point in response to detecting impeded wireless connection

• US 6,188,681 B1
• Filed: 04/01/1998
• Issued: 02/13/2001
• Est. Priority Date: 04/01/1998
• Status: Expired due to Term

• Current Assignee: Symbol Technologies, LLC (Zebra Technologies Corporation)
• Original Assignee: Symbol Technologies, Inc. (Zebra Technologies Corporation)
• Inventors: Vesuna, Sarosh N.
• Primary Examiner(s): Vincent, David R.
• Application Number:
  US09/053,072
• Time in Patent Office: 1,049 Days
• Field of Search: 370/230, 370/216, 370/217, 370/221, 370/328-9, 370/331-33, 370/338, 370/400-402, 370/428, 370/225, 455/517, 455/67.3, 455/466, 455/436, 455/437-9
• US Class Current: 370/338
• CPC Class Codes: H04W 48/16 Discovering, processing access restriction or access information
• CPC Class Codes: H04W 48/20 Selecting an access point
• CPC Class Codes: H04W 76/10 Connection setup
• CPC Class Codes: H04W 76/20 Manipulation of established connections
• CPC Class Codes: H04W 84/12 WLAN [Wireless Local Area Networks]

Abstract

When a connection between a remote unit (MU) and a first stationary access point (SAP) in a wireless network is impeded, an alternative connection between the MU and a second stationary access point is set up using information from announcement messages. The announcement messages are transmitted to notify MUs about messages waiting to be transferred, but the MU looking for an alternative to the impeded connection uses the announcement message to determine other stationary access points it may communicate with. This eliminates congestion normally caused by the MU performing dedicated probing to determine alternative stationary access points. Probing messages and probing response messages often cause congestion in a network.

Claims

1. A method of operating a data communications network including a plurality of access points operatively connected to a host computer and a plurality of remote mobile wireless units, at least one of the remote units located within communication range of at least two access points and normally associated with and in communication with one of said at least two access points, comprising:

(a) establishing communication and association between a first remote unit and a first access point;

(b) determining, in said first remote unit, that communication between the first remote unit and the first access point has been impeded;

(c) receiving in said first remote unit announcement messages broadcast over the airwaves, each message having an identification of particular ones of said remote units that have data messages waiting for transmission to said particular ones of said remote units;

(d) determining, in said first remote unit, the identity of the access point sending the announcement message; and

(e) sending from a said remote unit a message including a request that said remote unit associate with the access point determined to be sending the announcement message.

15. The method according to claim 1, wherein the step of determining the identity includes:

extracting the identity from a source field in said announcement message.

16. The method according to claim 1, wherein the remote unit comprises:

a handheld data-gathering unit.

17. The method according to claim 1, wherein the step of detecting that communication has been impeded includes:

detecting that the connection has been lost.

18. The method according to claim 1, wherein the step of detecting that communication has been impeded includes:

detecting a connection condition that would normally cause probing.

2. A method of associating a remote mobile unit to a second access point when a connection between the remote unit and a first access point becomes impeded, comprising:

detecting when a connection between a remote unit and a first access point is impeded;

receiving at the remote unit an announcement message from a second access point, the announcement message containing undelivered message information;

determining identity information of the second access point based on the announcement message; and

requesting association between the remote unit and the second access point using the identity information.

3. The method according to claim 2, wherein the step of determining identity information includes a substep of:

extracting the identity information from a source field of the announcement message.

4. The method according to claim 2, further including the step of:

receiving at the remote unit beacon messages having timing information for synchronizing access points.

19. The method according to claim 2, wherein a host connects the first access point to the second access point.

20. The method according to claim 2, wherein the remote unit comprises:

a handheld data-gathering unit.

21. The method according to claim 2, wherein the step of detecting includes:

detecting that the connection has been lost.

22. The method according to claim 2, wherein the step of detecting includes:

detecting a connection condition that would normally cause probing.

5. An apparatus for associating a remote mobile unit to a second access point when a connection between the remote unit and a first access point becomes impeded, comprising:

means for detecting when a connection between a remote unit and a first access point is impeded;

means for receiving at the remote unit an announcement message from a second access point, the announcement message containing undelivered message information;

means for determining identity information of the second access point based on the announcement message; and

means for requesting association between the remote unit and the second access point using the identity information.

6. The apparatus according to claim 5, wherein the means for determining identity information comprises:

means for extracting the identity information from a source field of the announcement message.

7. The apparatus according to claim 5, further comprising:

means for receiving at the remote unit beacon messages having timing information for synchronizing access points.

23. The apparatus according to claim 5, further comprising:

a host for connecting the first access point to the second access point.

24. The apparatus according to claim 5, wherein the remote unit comprises:

a handheld data-gathering unit.

25. The apparatus according to claim 5, wherein the detecting element comprises:

a lost connection detector for detecting that the connection has been lost.

26. The apparatus according to claim 5, wherein the detecting element comprises:

a connection detector for detecting a connection condition that would normally cause probing.

8. An apparatus for associating a remote mobile unit to a second access point when a connection between the remote unit and a first access point becomes impeded, comprising:

a detecting element for detecting when a connection between a remote unit and a first access point is impeded;

a receiver element for receiving at the remote unit an announcement message from a second access point, the announcement message containing undelivered message information;

an identity element for determining identity information of the second access point based on the announcement message; and

an association requestor element for requesting association between the remote unit and the second access point using the identity information.

9. The apparatus according to claim 8, wherein the identity element comprises:

an extracting element for extracting the identity information from a source field of the announcement message.

10. The apparatus according to claim 8, further comprising:

a beacon message receiving element for receiving at the remote unit beacon messages having timing information for synchronizing access points.

11. The apparatus according to claim 8, wherein a host connects the first access point to the second access point.

12. The apparatus according to claim 8, wherein the remote unit comprises:

a handheld data-gathering unit.

13. The apparatus according to claim 8, wherein the detecting element comprises:

a lost connection detector for detecting that the connection has been lost.

14. The apparatus according to claim 8, wherein the detecting element comprises:

a connection detector for detecting a connection condition that would normally cause probing.