Multi-channel self-interference cancellation method and apparatus for relayed communication

• US 6,725,017 B2
• Filed: 12/05/2001
• Issued: 04/20/2004
• Est. Priority Date: 12/05/2001
• Status: Expired due to Term

• Current Assignee: ViaSat Incorporated
• Original Assignee: ViaSat Incorporated
• Inventors: Blount, Richard, Irvine, David H.
• Primary Examiner(s): Trost, William
• Assistant Examiner(s): TORRES, MARCOS L
• Application Number:
  US10/006,534
• Publication Number:
  US 20030104787A1
• Time in Patent Office: 867 Days
• Field of Search: 455/63, 455/67.3, 455/115, 455/225, 455/218, 455/278.1, 455/283, 455/284, 455/296, 455/303, 455/304, 455/305, 455/306, 455/307, 455/16
• US Class Current: 455/67.13
• CPC Class Codes: H04B 1/525 with means for reducing leakage of transmitter signal into the receiver
• CPC Class Codes: H04B 7/18517 Transmission equipment in earth stations
• CPC Class Codes: H04B 7/2606 Arrangements for base station coverage control, e.g. by using relays in tunnels

Abstract

Multi-channel self-interference cancellation is provided in relayed electromagnetic communication between a first device and one or more other devices on one or more shared frequency channels. Specifically, near signals are generated at the first device and transmitted to a relay station. A composite signal is received at the first device from the relay station containing relayed versions of the near signals and relayed versions of remote signals transmitted from the one or more other devices, the composite signal having frequency channels including the one or more shared frequency channels, each shared frequency channel occupied by at least one of the relayed near signals and one of the relayed remote signals. One or more cancellation signals are selectively generated, each having a frequency band corresponding to one of the shared frequency channels. The cancellation signals are combined with the composite signal to produce a desired signal representing the relayed remote signals.

Claims

1. A method for providing self-interference cancellation in relayed electromagnetic communication between a first device and one or more other devices through a relay station comprising the steps of:

generating at said first device a plurality of near signals;

simultaneously transmitting said near signals from said first device to said relay station;

receiving at said first device a composite signal from said relay station, said composite signal containing relayed versions of said near signals and relayed versions of a plurality of remote signals transmitted from said one or more other devices, said composite signal having multiple frequency channels including one or more shared frequency channels, each said shared frequency channel being occupied by at least one of said relayed near signals and one of said relayed remote signals;

selectively generating one or more cancellation signals, each said cancellation signal having a frequency band corresponding to one of said shared frequency channels, each said cancellation signal representing a phase-inverted version of the relayed near signal occupying said one of said shared frequency channels; and

combining said cancellation signals with said composite signal to produce a desired signal representing said relayed remote signals.

2. The method of claim 1, wherein said cancellation signals are generated along one or more parallel paths and combined with said composite signal to produce said desired signal.

3. The method of claim 1, wherein said composite signal is processed by one or more cascaded stages to produce said desired signal, wherein at each said cascaded stage, one of said cancellation signals is generated and combined with said composite signal.

4. The method of claim 1, wherein said step of selectively generating said one or more cancellation signals further comprises, for each cancellation signal:

downconverting said composite signal such that said one of said shared frequency channels of said composite signal is frequency shifted to baseband to produce a single channel composite signal;

using said single channel composite signal, generating an estimate signal estimating the relayed near signal occupying said one of said shared frequency channels; and

upconverting said estimate signal to a frequency associated with said one of said shared frequency channels to produce said cancellation signal.

5. The method of claim 1, wherein said step of selectively generating said one or more cancellation signals further comprises, for each cancellation signal:

frequency-, phase-, and time-correlating a representation of said composite signal corresponding to said one of said shared frequency channels with a representation of the local near signal occupying said one of said shared frequency channel.

6. The method of claim 5, further comprising to step of:

filtering a signal resulting from said correlation using an adaptive filter, said adaptive filter receiving via a feedback path a representation of said desired signal corresponding to said one of said shared frequency channels.

7. The method of claim 1, wherein said step of selectively generating said one or more cancellation signals further comprises, for each cancellation signal:

from said composite signal, demodulating the relayed near signal occupying said one of said shared frequency channels to produce a demodulated signal; and

remodulating said demodulated signal.

8. The method of claim 1, wherein said step of selectively generating said one or more cancellation signals further comprises, for each cancellation signal:

generating from said composite signal a carrier signal corresponding to said one of said shared frequency channels; and

using said carrier signal, modulating an information sequence taken from a transmit path of said first device.

9. The method of claim 1, wherein at least one of said shared frequency channels is dynamically re-assigned to a new frequency bad using a control unit.

10. A system for providing self-interference cancellation in relayed electromagnetic communication between a first device and one or more other devices through a relay station, the system comprising:

means for generating at said first device a plurality of near signals;

means for simultaneously transmitting said near signals from said first device to said relay station;

means for receiving at said first device a composite signal from said relay station, said composite signal containing relayed versions of said near signals and relayed versions of a plurality of remote signals transmitted from said one or more other devices, said composite signal having multiple frequency channels including one or more shared frequency channels, each said shared frequency channel being occupied by at least one of said relayed near signals and one of said relayed remote signals;

means for selectively generating one or more cancellation signals, each said cancellation signal having a frequency band corresponding to one of said shared frequency channels, each said cancellation signal representing a phase-inverted version of the relayed near signal occupying said one of said shared frequency channels; and

means for combining said cancellation signals with said composite signal to produce a desired signal representing said relayed remote signals.