Methods and communications terminals for increasing capacity CDMA communications nerworks

• US 20030091018A1
• Filed: 11/14/2001
• Published: 05/15/2003
• Est. Priority Date: 11/14/2001
• Status: Active Grant

• Current Assignee: Google Technology Holdings LLC (Alphabet Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Oliver, John, Nguyen, Mymy, Mallette, Alexandre
• Granted Patent: US 6,661,809 B2
• Time in Patent Office: Days
• US Class Current: 370/342
• CPC Class Codes: H04B 1/7107 Subtractive interference cancellation
• CPC Class Codes: H04B 1/7115 Constructive combining of multi-path signals, i.e. RAKE receivers

Abstract

A method in a code division multiple access communication system having network infrastructure and a plurality of mobile terminals, including transmitting (210) composite signal comprising a synchronization signal and another non-orthogonal signal from the network infrastructure, receiving (220) the composite signal at the plurality of mobile terminals of the code division multiple access communication system, and increasing forward link capacity of the code division multiple access communication system by canceling (230) the synchronization signal from at least some of the plurality of mobile terminals.

Claims

1. A method in a code division multiple access mobile communications terminal, comprising:

receiving a first signal at the terminal;

receiving a second signal at the terminal, the first signal non-orthogonal to the second signal;

increasing forward link capacity of a code division multiple access communication system from which the first and second non-orthogonal signals are received by canceling one of the first and second signals at a rake processing portion of the terminal.

2. The method of claim 1, first signal is a synchronization signal, increasing forward link capacity by canceling the synchronization signal at the Rake processing portion of the terminal.

3. The method of claim 2, canceling the synchronization signal at the Rake processing portion of the terminal only when the synchronization signal has a strength greater than a predetermined threshold.

4. The method of claim 2, the synchronization signal is a composite signal comprising primary and secondary components, increasing forward link capacity by canceling the primary and secondary components of the synchronization signal.

5. The method of claim 1, canceling the first signal by subtracting first signal estimated interference terms from a Rake finger of the Rake processing portion of the terminal.

6. The method of claim 1, receiving the first and second signals by receiving a composite signal comprising the first and second signals.

7. The method of claim 6, the first signal is a synchronization signal, increasing forward link capacity by canceling the synchronization signal by subtracting estimated synchronization signal interference terms from the Rake processing portion of the terminal.

8. The method of claim 7, canceling the synchronization signal by subtracting synchronization signal interference terms from less than all Rake fingers of the Rake processing portion of the terminal.

9. The method of claim 7, canceling the synchronization signal by subtracting corresponding synchronization signal interference terms from all Rake fingers of the Rake processing portion of the terminal.

10. A method in a code division multiple access communication system including a network of base stations, comprising:

transmitting a composite signal comprising first and second non-orthogonal signals from a base station of the code division multiple access communication system;

receiving the composite signal at a mobile terminal in the code division multiple access communication system;

increasing forward link capacity of the code division multiple access communication system by canceling one of the first and second non-orthogonal signals at the mobile terminal.

11. The method of claim 10, one of the first and second signals is a synchronization signal non-orthogonal to the other of the first and second signals, increasing forward link capacity by canceling the synchronization signal at the mobile terminal by subtracting estimated synchronization signal interference terms from a Rake processing portion of the mobile terminal.

12. The method of claim 11, transmitting the synchronization signal in bursts from the base station of the code division multiple access communication system, canceling the synchronization signal bursts at the mobile terminal by subtracting estimated synchronization signal interference terms from the Rake processing portion of the mobile terminal in synchronization with the synchronization signal bursts.

13. The method of claim 11, canceling the synchronization signal at the mobile terminal by subtracting synchronization signal interference terms from all Rake fingers of the Rake processing portion of the mobile terminal.

14. The method of claim 11, canceling the synchronization signal at the mobile terminal by subtracting synchronization signal interference terms from less than all Rake fingers of the Rake processing portion of the mobile terminal.

15. The method of claim 11, canceling the synchronization signal from the Rake processing portion of the mobile terminal only when a characteristic of the synchronization signal exceeds a predetermined threshold.

16. A method in a code division multiple access communication system comprising network infrastructure and a plurality of mobile terminals, comprising:

transmitting composite signal comprising a synchronization signal and another non-orthogonal signal from the network infrastructure of the code division multiple access communication system;

receiving the composite signal at the plurality of mobile terminals of the code division multiple access communication system;

increasing forward link capacity of the code division multiple access communication system by canceling the synchronization signal from at least some of the plurality of mobile terminals.

17. The method of claim 16, canceling the synchronization signal from a Rake processing portion of the mobile terminals by subtracting estimated synchronization signal interference terms from Rake finger outputs of the mobile terminals.

18. The method of claim 16, canceling the synchronization signal from a Rake processing portion of the mobile terminals only when the synchronization signal exceeds a predetermined threshold.

19. The method of claim 16, canceling the synchronization signal at the mobile terminal by subtracting synchronization signal interference terms for less than all Rake fingers of the Rake processing portion of the mobile terminal.

20. The method of claim 16, canceling the synchronization signal at the mobile terminal by subtracting synchronization signal interference terms for all Rake fingers of the Rake processing portion of the mobile terminal.