Method for selecting a signal, and a cellular radio system

• US 6,038,458 A
• Filed: 12/30/1996
• Issued: 03/14/2000
• Est. Priority Date: 12/30/1996
• Status: Expired due to Fees

• Current Assignee: Nokia Telecommunications Oy (Nokia Corporation)
• Original Assignee: Nokia Telecommunications Oy (Nokia Corporation)
• Inventors: Siira, Mikko
• Primary Examiner(s): Bost, Dwayne D.
• Assistant Examiner(s): MAUNG, NAY AUNG
• Application Number:
  US08/774,600
• Time in Patent Office: 1,170 Days
• Field of Search: 455/422, 455/436, 455/503, 455/524, 455/525, 455/460, 455/442, 370/331
• US Class Current: 455/560
• CPC Class Codes: H04B 7/022 Site diversity; Macro-diversity using two or more spaced independent antennas H04B7/04
• CPC Class Codes: H04B 7/0491 using two or more sectors, i.e. sector diversity
• CPC Class Codes: H04W 36/18 for allowing seamless reselection, e.g. soft reselection
• CPC Class Codes: H04W 88/181 Transcoding devices; Rate adaptation devices

Abstract

A method for selecting a signal used in a cellular radio system having base stations and a vocoder encoding a signal. The vocoder is operationally connected to the base stations via transmission paths of different lengths. The base stations receive a signal encoded by the vocoder in the forward direction and transmit a signal to the vocoder in the reverse direction. The cellular radio system includes selectors that are separate from the base stations and that are arranged to select at least one signal to be transmitted to the vocoder from the signals received by the base stations in the reverse direction. The selectors are arranged to distribute to the base stations the signal arriving from the vocoder in the forward direction.

Claims

1. A method for selecting a signal in a cellular radio system which includes a plurality of base stations, a vocoder for encoding signals, and transmission paths of different lengths connecting said vocoder with respective ones of said base stations, so that said base stations are arranged to receive a respective signal in a forward direction and to transmit a respective signal in a reverse direction, said method comprising:

providing at least one selector, each said selector being located at a location which is geographically separated from said vocoder;

selecting by said at least one selector at least one reverse direction signal for transmission to said vocoder from signals arriving via respective ones of said transmission paths in said reverse direction;

distributing by said at least one selector a forward direction signal from said vocoder via respective ones of transmission said paths, in said forward direction, to respective ones of said base stations; and

concatenating said base stations such that said transmission paths extend from base station to base station, and said forward direction signal propagates from base station to base station as one signal,

wherein said selecting includes measuring and comparing a quality of said at least one reverse direction signal, and transmitting to said vocoder, a signal, from among said at least one reverse direction signal, having a highest quality.

2. The method of claim 1, wherein one of said transmission paths is a shortest transmission path connecting said vocoder with a respective one said base station,

said method further comprising:

locating said at least one selector at said respective one said base station.

3. The method of claim 1, further comprising;

locating said at least one selector at one of said base stations.

4. The method of claim 1, wherein

said concatenating said base stations to propagate said at least one reverse direction signal selected by said at least one selector from base station to base station to said vocoder, and to propagate said forward direction signal distributed by said at least one selector from base station to base station to respective ones of said base stations.

5. The method of claim 1, wherein

said concatenating said base stations is such that said selecting and said distributing are carried out separately at said plurality of said base stations.

6. The method of claim 1, wherein

said selecting of a signal having a highest quality is based on at least one of measuring correctness, measuring signal-to-noise ratio, obtained from convolutional coding, and use of a checksum of parity bits.

7. The method of claim 1, wherein

said distributing includes causing each said forward direction signal, as propagated to respective ones of said base stations, to contain information, wherein said information contained in each said forward direction signal is the same.

8. The method of claim 1, further comprising:

conducting said method of selecting in conjunction with conducting a soft hand-off of a mobile station from one to another of said base stations, in which, when said selecting and said distributing, said one and another of said base stations both transmit a reverse direction signal and receive a forward direction signal containing information, wherein said information contained in said forward direction signal and said reverse direction signal is the same.

9. The method of claim 1, wherein said cellular radio system further includes a base station controller which controls said base stations, and a mobile services switching center, and wherein said providing further includes

placing said vocoder in said mobile services switching center, said mobile services switching center being geographically separate from said base station controller.

10. A cellular radio system, comprising:

a plurality of base stations, said base stations being concatenated such that a plurality of transmission paths extend from base station to base station, and a forward direction signal propagates from base station to base station as one signal;

a vocoder for encoding signals;

said plurality of transmission paths of different lengths at least some of which are relative to one another, operationally connecting said vocoder to respective ones of said base stations, so that said base stations are arranged to receive, in a forward direction, signals encoded by said vocoder and to transmit, in a reverse direction, signals towards said vocoder; and

a selector located geographically separately from said base stations, and arranged to select from among signals received by said base stations at least one signal for transmission to said vocoder and to distribute to respective ones of said base stations encoded signals arriving at said selector from said vocoder, wherein said selector measures and compares signal quality of signals transmitted by said base stations.

11. The cellular radio system of claim 10, wherein

said plurality of paths include said base stations being concatenated so that signals selected and distributed by said selector propagate from base station to base station.

12. The cellular radio system of claim 10, wherein

said selector selects from among said signals transmitted by said base stations a best quality signal, based on said measuring and comparing.

13. The cellular radio system of claim 10 or 11, wherein

said selector is co-located with a respective one of said base stations and said one of said base stations having a shortest one of said transmission paths.

14. The cellular radio system of claim 10 or 11, further comprising:

a base station controller which controls said base stations; and

a mobile services switching center,

wherein said vocoder is located in said mobile services switching center, and

wherein said mobile services switching center is geographically separate from said base station controller.