LEAKAGE CANCELLATION A MULTIPLE-INPUT MULTIPLE-OUTPUT TRANSCEIVER

• US 20160156381A1
• Filed: 06/18/2013
• Published: 06/02/2016
• Est. Priority Date: 06/18/2013
• Status: Abandoned Application

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Rydstr?m, Mats, Coldrey, Mikael, Tageman, Ola
• Application Number:
  US14/897,059
• Publication Number:
  US 20160156381A1
• Time in Patent Office: Days
• CPC Class Codes: H04B 1/10 Means associated with receiver for limiting or suppressing noise or interference
• CPC Class Codes: H04B 1/525 with means for reducing leakage of transmitter signal into the receiver
• CPC Class Codes: H04B 7/0413 MIMO systems
• CPC Class Codes: H04L 5/14 Two-way operation using the same type of signal, i.e. duplex

Abstract

A transceiver 100 for simultaneous transmission and reception of communication signals in a multiple-input multiple-output, MIMO, system allowing operation on at least partly overlapping frequency bands. The transceiver 100 comprising an antenna arrangement 110, a duplex arrangement 120, and a modem unit 130. The duplex arrangement 120 being adapted to forward a transmit signal T1 from the modem unit to the antenna arrangement 110. The duplex arrangement 120 also being adapted to receive a receive signal R1 from the antenna arrangement 110 and to forward an interference suppressed receive signal R2 to the modem unit. The duplex arrangement 120 comprising an interference cancellation unit adapted to generate the interference suppressed receive signal R2 by combining the receive signal R1 from the antenna arrangement and the transmit signal T1.

Claims

1. A transceiver for simultaneous transmission and reception of communication signals in a multiple-input multiple-output (MIMO) system, the transceiver comprising:

an antenna arrangement,

a duplex arrangement, and

a modem unit,

the duplex arrangement being adapted to receive a transmit signal from the modem unit, transmit a first part of the transmit signal to the antenna arrangement, and receive a receive signal from the antenna arrangement,

the duplex arrangement comprising an interference cancellation (IC) unit adapted to generate an interference suppressed receive signal by combining the receive signal and the transmit signal, and

the duplex arrangement being further adapted to transmit the interference suppressed receive signal to the modem unit.

2. The transceiver of claim 1, wherein the receive signal occupying a first frequency band, the first part of the transmit signal occupying a second frequency band, and wherein the first and second frequency bands are at least partly overlapping, the transceiver thus being arranged to simultaneously transmit and receive communication signals in a MIMO system on at least partly overlapping frequency bands.

3. The transceiver of claim 1, wherein the antenna arrangement is part of a Line Of Sight (LOS) multiple-input multiple output (MIMO) antenna arrangement, and wherein the transmit and receive signals comprises a plurality of data streams, arranged to be transmitted over a plurality of LOS-MIMO channels.

4. The transceiver of claim 1, wherein the IC unit comprises at least one duplex coupler arranged to connect the antenna arrangement to at least one modulator and at least one demodulator comprised in the modem unit, the duplex coupler being arranged to forward part of the transmit signal from the at least one modulator to the antenna arrangement as the first part of the transmit signal, and also to forward the receive signal from the antenna arrangement to the at least one demodulator as the interference suppressed receive signal, wherein the interference suppressed receive signal is arranged to be isolated from the transmit signal.

5. The transceiver of claim 1, wherein

the IC unit comprises a set of adaptive filters arranged to receive and to filter a second part of the transmit signal received from the modem unit to generate a set of filtered transmit signals,

the IC unit further being adapted to combine the receive signal with the set of filtered transmit signals to generate the interference suppressed receive signal,

the set of adaptive filters being arranged to have transfer functions determined by a control signal,

the transceiver further comprising a control unit adapted to generate the control signal, which control signal is arranged to determine the transfer functions of the set of adaptive filters, the control signal having a setting to reduce the power of an interference signal comprised in the interference suppressed receive signal, and

said interference signal originating at least in part from the transmit signal.

6. The transceiver of claim 5, wherein the adaptive filters are arranged to receive and to filter a second part of the transmit signal received from the modem unit via the duplex coupler.

7. The transceiver of claim 1, wherein

the duplex arrangement comprises a polarization diplexer connected to the antenna arrangement,

the polarization diplexer being arranged to receive the receive signal from the antenna arrangement, and to split the receive signal into horizontal and vertical receive components, as well as to output horizontal and vertical receive components on horizontal and vertical polarization ports as first and second receive signals, respectively,

the horizontal and vertical polarization ports being connected to first and second IC units, respectively,

the first IC unit being adapted to receive a first transmit signal and a second transmit signal from the modem unit and to forward a first part of the first transmit signal to the horizontal polarization port,

the second IC unit also being adapted to receive the first transmit signal and the second transmit signal from the modem unit and to forward a first part of the second transmit signal to the vertical polarization port,

the first IC unit being adapted to receive the first receive signal from the horizontal polarization port and to generate a first interference suppressed receive signal by processing and combining the first and second transmit signal with the first receive signal,

the second IC unit being adapted to receive the second receive signal from the vertical polarization port and to generate a second interference suppressed receive signal by processing and combining the first and second transmit signal with the second receive signal, and

the first and second IC units further being adapted to forward said first and second interference suppressed receive signals, respectively, to the modem unit.

8. The transceiver of claim 1, wherein the antenna arrangement comprises first and second antenna units disposed a pre-determined distance apart, the duplex arrangement comprising first and second IC units, the first and second IC unit being adapted to receive a first transmit signal and a second transmit signal, respectively, from the modem unit, the first IC unit being adapted to forward a first part of the first transmit signal to the first antenna unit, the second IC unit being adapted to forward a first part of the second transmit signal to the second antenna unit, the first IC unit being adapted to receive a first receive signal from the first antenna unit and to generate a first interference suppressed receive signal by processing and combining the first transmit signal with the first receive signal, the second IC unit being adapted to receive a second receive signal from the second antenna unit and to generate a second interference suppressed receive signal by processing and combining the first transmit signal with the second receive signal, the first and second IC units further being adapted to forward said first and second interference suppressed receive signals to the modem unit, respectively, said interference signals originating from the first and second transmit signal.

9. The transceiver of claim 8, wherein the first and second IC units are arranged to receive also the second and the first transmit signal, respectively, and to suppress an interference signal by processing and combining the second transmit signal with the first receive signal and the first transmit signal with the second receive signal, respectively, to generate the first and the second interference suppressed receive signal, respectively.

10. The transceiver of claim 1, wherein the first part of the transmit signal arranged to pass from the duplex arrangement to the antenna arrangement, is passed over the same physical interface as the receive signal arranged to pass from the antenna arrangement to the duplex arrangement interface to the antenna arrangement.

11. The transceiver of claim 1, wherein the first part of the transmit signal arranged to pass from the duplex arrangement to the antenna arrangement, and the receive signal arranged to pass from the antenna arrangement to the duplex arrangement are transmitted and received via separate physical interfaces to the antenna arrangement.

12. The transceiver of claim 11, wherein the IC unit comprises an antenna port, a transmit port, a receive port, and a control port, the IC unit further comprising a duplex coupler, and a first adaptive filter, the duplex coupler being arranged to receive a transmit signal on the transmit port, and to forward a first part of the transmit signal from the transmit port to the antenna port, and to forward a second part of the transmit signal from the transmit port to an input port of the first adaptive filter, the duplex coupler being adapted to suppress coupling between transmit port and receive port, the duplex coupler further being arranged to receive a receive signal from the antenna port, and a first filtered signal from the first adaptive filter, the duplex coupler being arranged to combine the receive signal with the first filtered signal into an interference suppressed receive signal, and to output said interference suppressed receive signal on the receive port, the IC unit further being arranged to receive a control signal of the transceiver on the control port, the first adaptive filter being arranged to have a transfer function determined by the control signal, the transceiver being adapted to generate a control signal with a setting to minimize an interference in the interference suppressed receive signal originating from the transmit signal, thus isolating the interference suppressed receive signal on the receive port from the transmit signal on the transmit port.

13. The transceiver of claim 12, wherein the IC unit further comprises a reference port, and a second adaptive filter, the second adaptive filter being arranged to receive a second transmit signal on the reference port, and to filter said second transmit signal to make a second filtered signal, the duplex coupler further being arranged to receive the second filtered signal from the second adaptive filter, and to combine the receive signal with the first and the second filtered signal into an interference suppressed receive signal, and to output said interference suppressed receive signal on the receive port, the second adaptive filter being arranged to have a transfer function determined by the control signal, the transceiver being adapted to generate a control signal with a value to suppress an interference originating from the second transmit signal in the interference suppressed receive signal.

14. The transceiver of claim 13, wherein the second adaptive filter comprises a filter bank, the filter bank in turn comprising a plurality of adaptive sub-filters, and wherein the signal arranged to be received on the reference port comprises a plurality of sub-reference signals, where each such sub-reference signal is arranged to be an input signal of one out of the plurality of adaptive sub-filters, the control signal being used to determine the transfer function of each of the plurality of adaptive sub-filters to minimize the sum of correlations between interference suppressed receive signal and sub-reference signals.

15. The transceiver of claim 12, wherein the first adaptive filter comprises a reflection type filter, wherein the first filtered signal is reflected back from the filter over a common physical interface used for both filter input signal and output filtered signal, the first adaptive filter being arranged to receive and to filter analog signals, and to output an analog filtered signal.

16. The transceiver of claim 12, in which the first adaptive filter comprises a transmission type filter, the first adaptive filter being arranged to receive an analog signal on a first interface and to filter the analog signal, and to output an analog filtered signal on a second physical interface different from the first physical interface.

17. The transceiver of claim 1, wherein the antenna arrangement comprises first and second antenna units disposed a pre-determined distance apart, the first and second antenna unit being arranged to have directive radiation patterns focused in a first and a second pre-determined direction, the IC unit 121 being adapted to combine the transmit signal and the receive signal by forwarding the transmit signal to the first antenna and forwarding a receive signal received at the second antenna unit from the second antenna unit to the modem unit, wherein said combining is via signal propagation of the transmit signal from the first antenna to the second antenna.

18. A method for the transmission and reception of communication signals in partly overlapping frequency bands in a multiple-input multiple output (MIMO) system, the method comprising:

receiving a transmit signal from a modem in a duplex arrangement,

forwarding, from the duplex arrangement, a first part of said transmit signal to an antenna arrangement,

receiving, in the duplex arrangement, a receive signal from the antenna arrangement,

suppressing an interference signal comprised in the receive signal by combining the receive signal and the transmit signal to generate an interference suppressed receive signal, which interference signal originates from the transmit signal, the interference suppressed receive signal occupying a first frequency band, the first part of the transmit signal occupying a second frequency band, the first and second frequency bands being at least partly overlapping, and

forwarding the interference suppressed receive signal from the duplex arrangement to the modem.

19. The method of claim 18, wherein the step of suppressing further comprises the step of filtering by a set of adaptive filters arranged to receive and to filter a second part of the transmit signal to generate a set of filtered signals, the step of suppressing also comprising the step of combining the receive signal with the set of filtered signals prior to generate an interference suppressed receive signal.

20. The method of claim 18, wherein the duplex arrangement comprises a polarization diplexer adapted to split a received dual-polarized signal into horizontal and vertical components prior to the step of suppressing, and to combine horizontal and vertical transmit components into a single dual-polarized transmit signal prior to the step of forwarding the first part of the transmit signal to the antenna arrangement.

21. The method of claim 18, wherein the antenna arrangement comprises first and second antenna units disposed a pre-determined distance apart, and wherein the step of suppressing comprises isolating the interference suppressed receive signal from the transmit signal by using first and second IC units, the first and second IC units being adapted to receive a first and a second transmit signal from the modem, respectively, the first and second IC units being adapted to forward a first part of the first and a first part of the second transmit signal, respectively, to the first and second antenna units, respectively, the first and second IC units further being adapted to receive a first and a second receive signal, respectively, from the first and second antenna units, respectively, and to isolate the first and second receive signal from the first and second transmit signal, respectively, prior to forwarding said isolated receive signals to the modem unit as first and second interference suppressed receive signals, respectively.