Enhanced cosite transmitter-receiver isolation

Patent metadata

Field	Value
Publication number	US-2017353210-A1
Application number	US-201715485186-A
Country	US
Kind code	A1
Filing date	Apr 11, 2017
Priority date	Apr 11, 2016
Publication date	Dec 7, 2017
Grant date	—

Abstract

Systems and methods for improving isolation between a cosite transmitter-receiver system. The transmitter may send a first plurality of transmit signals from multiple transmit ports. The first plurality of transmit signals may be related to one another by a first set of complex weights. The receiver may detect channel-impaired versions of the first plurality of transmit signals at one or more receive ports. The receiver may analyze channel-impaired versions of the first plurality of transmit signals to estimate channel state information. The transmitter may use the channel state information to determine a second set of complex weights which will reduce the power received at one or more ports of the receiver when applied to a second plurality of transmit signals. The second set of complex weights may vary with frequency.

First claim

What is claimed is:

1 . A method for improving isolation of a receiver from a transmitter, the method comprising:
transmitting a first plurality of transmit signals from multiple ports of the transmitter, the first plurality of transmit signals being related to one another by a first set of complex weights; receiving channel-impaired versions of the first plurality of transmit signals at one or more ports of the receiver, the channel-impaired versions of the first plurality of transmit signals propagating from the transmitter to the receiver via one or more propagation channels; analyzing the channel-impaired versions of the first plurality of transmit signals to estimate channel state information for the one or more propagation channels; and using the channel state information to determine a second set of complex weights which will reduce the power received at one or more ports of the receiver when applied to a second plurality of transmit signals, the second set of complex weights varying with frequency.

2 . The method of claim 1 , wherein the receiver estimates the channel state information.

3 . The method of claim 2 , wherein the receiver sends the channel state information to the transmitter via a feedback communication channel which is distinct from the one or more propagation channels.

4 . The method of claim 3 , wherein the feedback communication channel is wired.

5 . The method of claim 3 , wherein the transmitter determines the second set of complex weights.

6 . The method of claim 5 , further comprising transmitting the second plurality of transmit signals from the multiple ports of the transmitter, the second plurality of transmit signals being related to one another by the second set of complex weights.

7 . The method of claim 1 , wherein the first plurality of transmit signals comprise pilot or preamble signals which are known by the receiver.

8 . The method of claim 1 , wherein the first plurality of transmit signals are unknown to the receiver.

9 . The method of claim 8 , further comprising blindly estimating the channel state information.

10 . The method of claim 8 , wherein the channel state information comprises relative channel state information.

11 . The method of claim 1 , wherein the transmitter and the receiver are a cosite pair.

12 . The method of claim 1 , wherein the first plurality of signals have a separability characteristic, and wherein the receiver determines the channel-impaired versions of the first plurality of signals using the separability characteristic.

13 . The method of claim 12 , wherein the separability characteristic comprises time multiplexing, frequency multiplexing, code multiplexing, beam multiplexing, or eigenmode multiplexing.

14 . The method of claim 1 , wherein the multiple ports of the transmitter are coupled to orthogonally-polarized antenna elements and the second set of complex weights are associated with a plurality of polarization states.

15 . The method of claim 1 , wherein the multiple ports of the transmitter are coupled to spatially-separated antenna elements having the same or different polarizations.

16 . The method of claim 1 , wherein the second set of complex weights comprises complex weights for each of a plurality of frequency sub-bands of each of the second plurality of transmit signals.

17 . The method of claim 1 , wherein the method is iteratively repeated as impairments of the one or more propagation channels change over time.

18 . The method of claim 1 , further comprising operating the transmitter and the receiver in full duplex mode.

19 . The method of claim 1 , wherein the first plurality of transmit signals include a repeated transmit waveform, and further comprising:
applying a first chip signal to a first instance of the repeated transmit waveform at the transmitter; and applying a negating second chip signal to a second instance of the repeated transmit waveform at the transmitter.

20 . The method of claim 19 , further comprising combining the received first instance of the repeated transmit waveform with the received second instance of the repeated waveform at the receiver, thereby at least partially canceling the receiver response to the first plurality of transmit waveforms.

21 . A system for improving isolation of a receiver from a transmitter, the system comprising:
a transmitter configured to send a first plurality of transmit signals using multiple ports, the first plurality of transmit signals being related to one another by a first set of complex weights; and a receiver configured to receive channel-impaired versions of the first plurality of transmit signals using one or more ports, the channel-impaired versions of the first plurality of transmit signals propagating from the transmitter to the receiver via one or more propagation channels, wherein the system is configured to analyze the channel-impaired versions of the first plurality of transmit signals to estimate channel state information for the one or more propagation channels; and wherein the system is further configured to use the channel state information to determine a second set of complex weights which will reduce the power received at one or more ports of the receiver when applied to a second plurality of transmit signals, the second set of complex weights varying with frequency.

Assignees

• Univ Notre Dame Du Lac

Inventors

• Pratt Thomas G
• Kossler Robert Daniel

Classifications

• H04B7/0626

  Channel coefficients, e.g. channel state information [CSI] · CPC title

• H04B1/44 Primary

  Transmit/receive switching · CPC title

• H04L1/00

  Arrangements for detecting or preventing errors in the information received {(correcting synchronisation H04L7/00)} · CPC title

• H04L25/024

  channel estimation algorithms · CPC title

• H04L25/0238 Primary

  using blind estimation · CPC title