Method of registering/-reassigning a call in a dual mode communication network

• US 5,574,973 A
• Filed: 03/16/1995
• Issued: 11/12/1996
• Est. Priority Date: 10/07/1992
• Status: Expired due to Fees

• Current Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Haug, John R., Rasky, Phillip D., Borth, David E.
• Primary Examiner(s): Urban, Edward F.
• Application Number:
  US08/405,572
• Time in Patent Office: 607 Days
• Field of Search: 455/33.1, 455/33.2, 455/33.4, 455/34.1, 455/34.2, 455/54.1, 455/56.1, 379/59, 379/60
• US Class Current: 455/435.2
• CPC Class Codes: H04W 36/14 Reselecting a network or an air interface
• CPC Class Codes: H04W 36/30 by measured or perceived connection quality data
• CPC Class Codes: H04W 48/18 Selecting a network or a communication service
• CPC Class Codes: H04W 60/00 Affiliation to network, e.g. registration; Terminating affiliation with the network, e.g. de-registration
• CPC Class Codes: H04W 76/20 Manipulation of established connections
• CPC Class Codes: H04W 92/02 Inter-networking arrangements

Abstract

Registration operates by sensing (106) the availability of a first communication system. A quality factor of a channel of the system is measured (111). A channel of the first system is selected if the quality factor of the channel exceeds a threshold (113). If selected, the subscriber attempts to register the call (114). If the registration fails, the availability of a second communication system is sensed (107). A quality factor of a channel of the second system is measured (111) and selected (113), if the quality factor exceeds a threshold. The subscriber will then attempt to register (114) with the second system. Reassignment operates by determining if the first system has reached a capacity limit (126). If it has, it determines if a channel on the second system is available (128). If available, a transfer of the call from the first to the second system will be attempted (132).

Claims

1. A method of registering a call in a dual mode communication network having a first communication system providing communication services in a first mode according to a first air interface protocol and a second communication system providing communication services in a second mode according to a second air interface protocol, said method comprising the steps of:

(a) sensing the availability of said first communication system at power-up of a subscriber unit;

(b) measuring a first quality factor of a plurality of channels of said first communication system;

(c) ranking said plurality of channels within said first communication system by said first quality factors;

(d) selecting a channel of said first communication system if said first quality factor of said channel exceeds a quality threshold, set to a first threshold level, of said first communication system;

(e) attempting to register said call with said first communication system on said channel;

(f) repeating said steps (d) and (e), if said attempted registration in said step (e) fails, until registration has been attempted on each of said plurality of channels of said first communication system for which said first quality factor exceeds said quality threshold and determining whether said call is registered with said first communication system;

(g) sensing the availability of said second communication system if said attempted registration of said call with said first communication system fails;

(h) measuring a second quality factor of a plurality of channels of said second communication system;

(i) ranking said plurality of channels within said second communication system by said second quality factors;

(j) selecting a channel of said second communication system if said second quality factor of said channel exceeds a quality threshold, set to a second threshold level, of said second communication system;

(k) attempting to register said call with said second communication system on said channel;

(l) repeating said steps (j) and (k), if said attempted registration in said step (k) fails, until registration has been attempted on each of said plurality of channels of said second communication system for which said second quality factor exceeds said quality threshold;

(m) setting said quality threshold of said first communication system to a third threshold level;

(n) setting said quality threshold of said second communication system to a fourth threshold level; and

(o) repeating said steps (a)-(l).

2. The method of claim 1 wherein each of said first and second quality factors comprise one of a received signal strength indicator (RSSI), a bit error rate (BER), a word error rate (WER), a carrier-to-interference ratio (C/I), and an intersymbol interference (ISI) rate.

3. The method of claim 1, wherein said first communication system comprises a low tier system and said second communication system comprises a high tier system.

4. The method of claim 1, wherein said first communication system comprises a wireless communication system.

5. The method of claim 1, wherein said second communication system comprises a cellular system.

6. The method of claim 1, wherein one of said first and second quality factors comprises a mobility factor.

7. The method of claim 6, wherein said mobility factor comprises one of a frequency offset factor and a channel availability indicator.

8. A method of registering a call in a dual mode communication network comprising the steps of:

receiving a first signal transmitted over a first channel of a first communication system via a first air interface protocol;

measuring a first quality factor of the first signal;

selecting a channel of said first communication system if said first quality factor exceeds a first quality threshold having a first threshold level;

attempting to register said call with said first communication system on said first channel;

determining whether said call is registered with said first communication system;

receiving a second signal transmitted via a second air interface protocol over a second channel of said second communication system;

measuring a second quality factor of said second signal;

selecting a channel of said second communication system if said second quality factor of said channel exceeds a second quality threshold having a second threshold level;

attempting to register said call with said second communication system on said second channel;

setting one of said first and second quality thresholds to a third threshold level; and

re-attempting to register said call with one of said first and second communication system if one of said first and second quality factors exceeds said third threshold level.

9. The method of claim 8, wherein said first communication system comprises a low tier system and said second communication system comprises a high tier system.

10. The method of claim 8, wherein said first communication system comprises a wireless communication system.

11. The method of claim 8, wherein said second communication system comprises a cellular system.

12. The method of claim 8, wherein one of said first and second quality factors comprises a mobility factor.

13. The method of claim 12, wherein said mobility factor comprises one of a frequency offset factor and a channel availability indicator.

14. The method of claim 8, wherein one of said first and second quality factors is selected from the group consisting essentially of a received signal strength indicator, a bit error rate, a word error rate, a carrier-to-interference ratio, and an intersymbol interference rate.

15. The method of claim 8, wherein said first air interface protocol supports a first traffic channel having a low tier framing structure.

16. The method of claim 15, wherein said second air interface protocol supports a second traffic channel having a high tier framing structure.

17. The method of claim 16, wherein at least a portion of said low tier framing structure substantially matches at least a portion of said high tier framing structure.