Primary control signal bus selection for radio heads based on propagation delay

• US 20030061422A1
• Filed: 09/26/2001
• Published: 03/27/2003
• Est. Priority Date: 09/26/2001
• Status: Active Grant

• Current Assignee: Ericsson, Inc. (Telefonaktiebolaget LM Ericsson)
• Original Assignee: Ericsson, Inc. (Telefonaktiebolaget LM Ericsson)
• Inventors: Repice, Joseph A., Shepherd, Johnny D.
• Granted Patent: US 6,788,961 B2
• Time in Patent Office: Days
• US Class Current: 710/107
• CPC Class Codes: H04W 88/085 Access point devices with remote components
• CPC Class Codes: H04W 92/20 between access points

Abstract

The selection of the primary control signal bus to use for a given radio head is based on propagation delay to the relevant radio head. A plurality of radio heads are cascaded in a chain with buffered error correction therebetween. At least first and second control interfaces connect to the chain and supply control information thereto via respective control signal busses, which may be virtual busses. The propagation delay from a first control interface to a first radio head over a first bus is determined. Likewise, the propagation delay from a second control interface to the first radio head over a second bus is determined. Thereafter, the radio head determines which control signal bus to select as its primary control signal bus based on the respective propagation delays between the first radio head and the first and second control interfaces.

Claims

1. A method implemented in a radio head of selecting a control signaling bus from a plurality of available control signaling busses, said method comprising:

determining propagation delays along at least two of said control signaling busses from a corresponding control interface to a first radio head; and

automatically selecting, by said first radio head, a primary control signaling bus from amongst said plurality of available control signaling busses based on said propagation delays.

2. The method of claim 1 further comprising:

forming a cascaded radio head chain comprising said first radio head and said at least two control signaling busses prior to said determining propagation delays;

subsequently changing the physical configuration of said radio head chain;

thereafter, re-determining the propagation delays along said at least two control signaling busses from said corresponding control interfaces to said first radio head; and

thereafter, automatically re-selecting, by said first radio head, a primary control signaling bus from amongst said plurality of available control signaling busses based on said re-determined propagation delays.

3. The method of claim 2 wherein changing the physical configuration of said system comprises adding or subtracting at least one radio head to/from said radio head chain.

4. The method of claim 1 wherein determining said propagation delays along said at least two of said control signaling busses from said corresponding control interface to said first radio head comprises determining said propagation delays from said control interfaces to said first radio head by counting hops along said control signaling busses between said corresponding control interfaces and said first radio head.

5. The method of claim 1 wherein determining said propagation delays along said at least two of said control signaling busses from said corresponding control interface to said first radio head comprises determining said propagation delays from said control interfaces to said first radio head by measuring a ping-response time along said control signaling busses between said corresponding control interfaces and said first radio head.

6. A method of operating a wireless communications system, said system comprising a plurality of physically separated radio heads cascaded in a chain and at least first and second control interfaces connected to said chain and supplying control information thereto via a plurality of virtual control signal busses connecting said control interfaces to said plurality of radio heads, including at least a first virtual control signal bus connecting said first control interface to said plurality of radio heads and a second virtual control signal bus connecting said second control interface to said plurality of radio heads, said method comprising:

determining the propagation delay from said first control interface to a first radio head over said first virtual control signal bus;

determining the propagation delay from said second control interface to said first radio head over said second virtual control signal bus; and

determining, by said first radio head, a primary control signal bus from amongst said plurality of virtual control signal busses based on said respective propagation delays between said first radio head and said control interfaces.

7. The method of claim 6 further comprising subsequently:

changing the physical configuration of said system;

thereafter, re-determining the propagation delay from said first control interface to said first radio head over said first virtual control signal bus and re-determining the propagation delay from said second control interface to said first radio head over said second virtual control signal bus; and

thereafter, re-determining, by said first radio head, a primary control signal bus from amongst said plurality of virtual control signal busses based on the respective propagation delays between said first radio head and said control interfaces.

8. The method of claim 7 wherein changing the physical configuration of said system comprises adding or subtracting at least one radio head to/from said chain.

9. The method of claim 6 wherein determining the propagation delay from said first control interface to said first radio head over said first virtual control signal bus comprises determining a first propagation delay from said first control interface to said first radio head over said first virtual control signal bus by said first control interface.

10. The method of claim 9 wherein said first control interface determining said first propagation delay from said first control interface to said first radio head over said first virtual control signal bus comprises said first control interface determining said first propagation delay by counting hops between said first control interface and said first radio head.

11. The method of claim 9 wherein said first control interface determining said first propagation delay from said first control interface to said first radio head over said first virtual control signal bus comprises said first control interface determining said first propagation delay by measuring a ping-response time between said first control interface and said first radio head over said first virtual control bus.

12. The method of claim 9 further comprising said first control interface communicating said first propagation delay to said first radio head.

13.he. The method of claim 6 wherein determining the propagation delay from said first control interface to said first radio head over said first virtual control signal bus comprises said first control interface determining respective propagation delays from said first control interface to a plurality of radio heads over said first virtual control signal bus.

14. The method of claim 13 further comprising said first control interface communicating said plurality of propagation delays to said first radio head.

15. The method of claim 14 wherein determining the propagation delay from said second control interface to said first radio head over said second virtual control signal bus comprises said second control interface determining a second propagation delay from said second control interface to said first radio head over said second virtual control signal bus, and further comprising said second control interface communicating said second propagation delay to said first radio head.

16. A method of operating a wireless communications system, said system comprising a plurality of radio heads cascaded in a chain with buffered error correction therebetween and at least first and second control interface units connected to said chain and supplying control information thereto via a plurality of control signal busses connecting said control interface units to said plurality of radio heads, said method comprising:

determining the propagation delay from a first control interface unit to a first radio head over a first control signal bus;

determining the propagation delay from a second control interface unit to said first radio head over a second control signal bus; and

selecting, by said first radio head, a primary control signal bus from amongst said plurality of control signal busses based on the respective propagation delays between said first radio head and said first and second control interface units.

17. The method of claim 16 wherein determining the propagation delay from said first control interface unit to said first radio head over said first bus comprises determining, by said first control interface unit, the propagation delay from said first control interface unit to said first radio head over said first bus.

18. The method of claim 16 further comprising subsequently:

changing the physical configuration of said system;

thereafter, re-determining the propagation delay from said first control interface unit to said first radio head over said first control signal bus and re-determining the propagation delay from said second control

interface unit to said first radio head over said second control signal bus; and

thereafter, re-selecting, by said first radio head, a primary control signal bus from amongst said plurality of control signal busses based on the respective propagation delays between said first radio head and said control interface units.

19. The method of claim 16 wherein determining the propagation delay from said first control interface unit to said first radio head over said first control signal bus comprises determining a first propagation delay from said first control interface unit to said first radio head over said first control signal bus by said first control interface unit.

20. The method of claim 19 wherein said first control interface unit determining said first propagation delay from said first control interface unit to said first radio head over said first control signal bus comprises said first control interface unit determining said first propagation delay by counting hops between said first control interface unit and said first radio head.

21. The method of claim 19 wherein said first control interface unit determining said first propagation delay from said first control interface unit to said first radio head over said first control signal bus comprises said first control interface unit determining said first propagation delay by measuring a ping-response time between said first control interface unit and said first radio head over said first control bus.

22. The method of claim 19 further comprising said first control interface unit communicating said first propagation delay to said first radio head.

23. The method of claim 16 wherein determining the propagation delay from said first control interface unit to said first radio head over said first control signal bus comprises said first control interface unit determining respective propagation delays from said first control interface unit to a plurality of radio heads over said first control signal bus.

24. The method of claim 23 further comprising said first control interface unit communicating said plurality of propagation delays to said first radio head.

25. The method of claim 24 wherein determining the propagation delay from said second control interface unit to said first radio head over said second control signal bus comprises said second control interface unit determining a second propagation delay from said second control interface unit to said first radio head over said second control signal bus, and further comprising said second control interface unit communicating said second propagation delay to said first radio head.

26. A wireless communications system, comprising:

a plurality of geographically separated radio heads cascaded in a chain;

at least first and second control interfaces connected to said chain and supplying control information thereto;

a plurality of virtual control signal busses connecting said control interfaces to said plurality of radio heads, including at least a first virtual control signal bus connecting said first control interface to said plurality of radio heads and a second virtual control signal bus connecting said second control interface to said plurality of radio heads;

wherein a radio head in said chain is adapted to determine which of said virtual control signal buses is primary based on the respective propagation delays from said control interfaces to said radio head.

27. The system of claim 26 wherein said first control interface is adapted to determine the propagation delay from said first control interface to said first radio head over said first control signal bus and communicate that propagation delay to said first radio head.

28. The system of claim 26 wherein each of said radio heads in said chain is adapted to determine which of said control signal buses is its primary control signal bus based on the respective propagation delays from said control interfaces to itself.