Method for selecting an alternate channel in a wireless communications system

• US 6,253,082 B1
• Filed: 02/08/1999
• Issued: 06/26/2001
• Est. Priority Date: 07/30/1998
• Status: Expired due to Term

• Current Assignee: Eagle Technology, LLC (L3Harris Technologies, Inc.)
• Original Assignee: The Whitaker Corporation (Meggitt PLC)
• Inventors: Hengeveld, Thomas
• Primary Examiner(s): Maung, Nay
• Assistant Examiner(s): PERSINO, RAYMOND B
• Application Number:
  US09/245,752
• Time in Patent Office: 869 Days
• Field of Search: 455/432, 455/434, 455/435, 455/436, 455/437, 455/438, 455/439, 455/443, 455/444, 455/450, 455/451, 455/452, 455/453, 455/509, 455/512, 455/515, 370/350, 370/330
• US Class Current: 455/436
• CPC Class Codes: H04W 36/0011 for data sessions of end-to-end connection
• CPC Class Codes: H04W 36/00835 Determination of neighbour cell lists
• CPC Class Codes: H04W 36/00837 Determination of triggering parameters for hand-off

Abstract

In a wireless communications system, upon making a decision to roam, the mobile chooses an alternate communications channel in a prioritized manner and evaluates the chosen channel for whether it is able to support a data link interconnection. Upon evaluating that a chosen channel is able to support a data link connection, the chosen channel is selected as the next best alternate channel on which to attempt a data link establishment procedure. The channels are chosen from a set of possible channels in an order including a home channel, an in area channel, and then any of the possible channels. Advantageously, the selection of the next best alternate channel provides increased probability of establishing and maintaining a data link over the selected channel as well as providing a certain amount of control communications traffic flow in the system.

Claims

1. A method of maintaining a wireless communications link between a mobile and a host by selecting a second channel between the mobile and the host in a wireless communications system when a first established data link connection over a first channel degrades, the method of comprising the steps of:

(a) choosing a channel from a set of potentially useful channels in the wireless communications system;

(b) attempting to obtain MAC (Medium Access Control) layer synchronization over the chosen channel;

(c) marking the chosen channel a useless if said synchronization is not achieved and repeating the process beginning at the step of choosing the channel;

(d) selecting the chosen channel if said synchronization is achieved; and

(e) establishing a data link connection over the selected channel if said synchronization is achieved.

2. A method of maintaining a wireless communications link between a mobile and a host as recited in claim 1 wherein the mobile performs the recited steps.

3. A method of maintaining a wireless communications link between a mobile and a host as recited in claim 1 wherein the set of potentially useful channels is a subset of a set of possible channels, and the method further comprises the step of resetting the set of potentially useful channels to include an entirety of the set of possible channels if said synchronization is achieved.

4. A method of maintaining a wireless communications link between a mobile and a host as recited in claim 3 wherein the step of choosing the channel from the set of potentially useful channels is prioritized wherein the prioritization comprises the steps of:

(a) choosing a home channel first if the home channel is also one of the potentially useful channels,

(b) choosing one of in area channels that is also one of the potentially useful channels if the home channel is not one of the potentially useful channels, and

(c) choosing any one channel from the set of potentially useful channels if the home and the in area channels are not one of the useful channels.

5. A method of maintaining a wireless communications link between a mobile and a host as recited in claim 4 wherein at least one of the home channel and the in are channels are predetermined.

6. A method of maintaining a wireless communications link between a mobile and a host as recited in claim 4 wherein the in area channels are defined by logical relation to the first channel.

7. A method of maintaining a wireless communications link between a mobile and a host as recited in claim 1 wherein the set of potentially useful channels is a subset of a set of possible channels, and the method further comprises the steps of:

(e) associating a utility flag with each channel in the set of possible channels;

(f) setting the utility flag to mark the chosen channels as useless if said synchronization is not achieved; and

(g) resetting the utility flag to mark the potentially useful channels.

8. A method of maintaining a wireless communications link between a mobile and a host as recited in claim 1, further comprising the step of;

associating a roaming flag with each channel in the set of possible channels, the roaming flag marking each channel as either tried or untried,

wherein the step of choosing the channel further comprises choosing the channel from the set of potentially useful channels that are also untried channels.

9. A method of maintaining a wireless communications link between a mobile and a host as recited in claim 8 wherein the step of choosing the channel from the set of potentially useful channels is prioritized.

10. A method of maintaining a wireless communications link between a mobile and a host as recited in claim 9 wherein the prioritization comprises the steps of:

(a) choosing a home channel first if the home channel is also one of the potentially useful channels,

(b) choosing one of in area channels that is also one of the potentially useful channels if the home channel is not one of the potentially useful channel and

(c) choosing any one channel from the set of potentially useful channels if the home and the in area channels are not one of the useful channels.

11. A method of maintaining a wireless communications link between a mobile and a host as recited in claim 10 wherein the home channel is predetermined.

12. A method of maintaining a wireless communications link between a mobile and a host as recited in claim 10 wherein the in area channels are predetermined.

13. A method of maintaining a wireless communications link between a mobile and a host as recited in claim 12 wherein the home channel is predetermined.

14. A method of maintaining a wireless communications link between a mobile and a host as recited in claim 10 wherein the in area channels are defined by logical relation to the first channel.

15. A method of maintaining a wireless communications link between a mobile and a host as recited in claim 1, wherein said step (b) attempts to obtain synchronization between a MAC layer of the host and a MAC layer of the mobile over the chosen channel.

16. A method of maintaining a wireless communications link between a mobile and a host as recited in claim 15, wherein said step (e) assigns a TEI (Temporary Equipment Identifier) value to be used by the mobile and the host during communications over the data link connection established in said step (e).

17. A method of maintaining a wireless communications link between a mobile and a host as recited in claim 16, wherein the wireless communications system is a wireless telephone communications system, and the host is a base station located in a cell of the wireless telephone communications systems.

18. A method of maintaining a wireless communications link between a mobile and a host by selecting a second channel between the mobile and the host in a wireless communications environment, the method comprising the steps of having a first established data link connection over a first channel, accepting a set of possible channels and selecting from the set of possible channels a second channel on which to establish a second data link connection, said selecting step comprising the steps of:

(a) choosing a channel from a set of potentially useful channels in the wireless communications environment;

(b) attempting to obtain MAC (Medium Access Control) layer synchronization over the chosen channel;

(c) marking the chosen channel as useless if said synchronization is not achieved and repeating the process beginning at the step of choosing;

(d) selecting the chosen channel if said synchronization is achieved; and

(e) establishing the second data link connection over the selected channel.

19. A method of maintaining a wireless communications link between a mobile and a host as recited in claim 18 wherein the mobile performs the recited steps.

20. A method of maintaining a wireless communications link between a mobile and a host as recited in claim 18 wherein the set of potentially useful channels is a subset of a set of possible channels, and the method further comprises the step of resetting the set of potentially useful channels to include an entirety of the set of possible channels if said synchronization is achieved.

21. A method of maintaining a wireless communications link between a mobile and a host as recited in claim 20 wherein the step of choosing the channel from the set of potentially useful channels is prioritized wherein the prioritization comprises the steps of:

(a) choosing a home channel first if the home channel is also one of the potentially useful channels,

(b) choosing one of in area channels that is also one of the potentially useful channels if the home channel is not one of the potentially useful channels, and

(c) choosing any one channel from the set of potentially useful channels if the home and the in area channels are not one of the useful channels.

22. A method of maintaining a wireless communications link between a mobile and a host as recited in claim 21 wherein at least one of the home channel and the in area channels are predetermined.

23. A method of maintaining a wireless communications link between a mobile and a host as recited in claim 21 wherein the in area channels are defined by logical relation to the first channel.

24. A method of maintaining a wireless communications link between a mobile and a host as recited in claim 18 wherein the set of potentially useful channels is a subset of a set of possible channels, and the method further comprises the steps of:

(e) associating a utility flag with each channel in the set of possible channels;

(f) setting the utility flag to mark the chosen channels as useless if said synchronization is not achieved; and

(g) resetting the utility flag to mark the potentially useful channels.

25. A method of maintaining a wireless communications link between a mobile and a host as recited in claim 18, further comprising the steps of:

associating a roaming flag with each channel in the set of possible channels, the roaming flag marking each channel as either tried or untried,

wherein the step of choosing the channel further comprises choosing the channel from the set of potentially useful channels that are also untried channels.

26. A method of maintaining a wireless communications link between a mobile and a host as recited in claim 25 wherein the step of choosing the channel from the set of potentially useful channels is prioritized.

27. A method of maintaining a wireless communications link between a mobile and a host as recited in claim 26 wherein the prioritization comprises the steps of:

(a) choosing a home channel first if the home channel is also one of the potentially useful channels,

(b) choosing one of in area channels that is also one of the potentially useful channels if the home channel is not one of the potentially useful channels, and

(c) choosing any one channel from the set of potentially useful channels if the home and the in area channels are not one of the useful channels.

28. A method of maintaining a wireless communications link between a mobile and a host as recited in claim 27 wherein at least one of the home channel and the in area channels are predetermined.

29. A method of maintaining a wireless communications link between a mobile and a host as recited in claim 27 wherein the in area channels are defined by logical relation to the first channel.

30. A method of maintaining a wireless communications link between a mobile and a host as recited in claim 18, wherein said step (b) attempts to obtain synchronization between a MAC layer of the host and a MAC layer of the mobile over the chosen channel.

31. A method of maintaining a wireless communications link between a mobile and a host as recited in claim 30, wherein said step (e) assigns a TEI (Temporary Equipment Identifier) value to be used by the mobile and the host during communications over the data link connection established in said step (e).

32. A method of maintaining a wireless communications link between a mobile and a host as recited in claim 31, wherein the wireless communications environment is a wireless telephone communications system, and the host is a base station located in a cell of the wireless telephone communications system.

33. A method of selecting a second channel between a mobile and a host in a wireless communications system when a first established data link connection over a first channel degrades, the method of comprising the steps of:

(a) choosing a channel from a set of potentially useful channels;

(b) attempting to obtain synchronization over the chosen channel;

(c) marking the chosen channel a useless if said synchronization is not achieved and repeating the process beginning at the step of choosing the channel;

(d) selecting the chosen channel if said synchronization is achieved; and

(e) establishing a data link connection over the selected channel if said synchronization is achieved,

wherein the step of choosing the channel includes the steps of,

(a1) choosing a home channel first if the home channel is one of a set of potentially useful channels,

(a2) choosing one in a set of one or more of in area channels that is also one of the potentially useful channels if the home channel is not one of the potentially useful channels, and

(a3) choosing any one channel from the set of potentially useful channels if the home and the in area channels are not one of the useful channels,

wherein the one or more in area channels are defined by logical relation to the first channel.