REDUCING LOCATION-DEPENDENT INTERFERENCE IN DISTRIBUTED ANTENNA SYSTEMS OPERATING IN MULTIPLE-INPUT, MULTIPLE-OUTPUT (MIMO) CONFIGURATION, AND RELATED COMPONENTS, SYSTEMS, AND METHODS

• US 20150003565A1
• Filed: 09/16/2014
• Published: 01/01/2015
• Est. Priority Date: 03/30/2012
• Status: Active Grant

• Current Assignee: Corning Optical Communications LLC (Corning Incorporated)
• Original Assignee: Corning Optical Communications LLC (Corning Incorporated)
• Inventors: George, Jacob, Ng'Oma, Anthony, Yang, Hejie
• Granted Patent: US 9,258,052 B2
• Time in Patent Office: Days
• US Class Current: 375/299
• CPC Class Codes: H04B 10/25753 Distribution optical network, e.g. between a base station and a plurality of remote units
• CPC Class Codes: H04B 7/024 Co-operative use of antennas of several sites, e.g. in co-ordinated multipoint or co-operative multiple-input multiple-output [MIMO] systems
• CPC Class Codes: H04B 7/0413 MIMO systems
• CPC Class Codes: H04B 7/0469 taking special antenna structures, e.g. cross polarized antennas into account
• CPC Class Codes: H04B 7/06 at the transmitting station
• CPC Class Codes: H04B 7/10 Polarisation diversity; Directional diversity

Abstract

Components, systems, and methods for reducing location-based interference in distributed antenna systems operating in multiple-input, multiple-output (MIMO) configuration are disclosed. Interference is defined as issues with received MIMO communications signals that can cause a MIMO algorithm to not be able to solve a channel matrix for MIMO communications signals received by MIMO receivers in client devices. These issues may be caused by lack of spatial (i.e., phase) separation in the received MIMO communications signals. Thus, to provide phase separation of received MIMO communication signals, multiple MIMO transmitters are each configured to employ multiple transmitter antennas, which are each configured to transmit in different polarization states. In certain embodiments, one of the MIMO communications signals is phase shifted in one of the polarization states to provide phase separation between received MIMO communication signals. In other embodiments, multiple transmitter antennas in a MIMO transmitter can be offset to provide phase separation.

Claims

1. A MIMO remote unit configured to wirelessly distribute MIMO communications signals to wireless client devices in a distributed antenna system, comprising:

a first MIMO transmitter comprising;

a first MIMO transmitter antenna configured to transmit MIMO communications signals in a first polarization and a second MIMO transmitter antenna configured to transmit MIMO communications signals in a second polarization different from the first polarization; and

a second MIMO transmitter comprising a third MIMO transmitter antenna configured to transmit MIMO communications signals in the first polarization and a fourth MIMO transmitter antenna configured to transmit MIMO communications signals in the second polarization;

the first MIMO transmitter configured to;

receive a first downlink MIMO communications signal in a first phase over a first downlink communications medium, and transmit the first downlink MIMO communications signal wirelessly as a first electrical downlink MIMO communications signal over the first MIMO transmitter antenna in the first polarization; and

receive a second downlink MIMO communications signal in the first phase over a second downlink communications medium, and transmit the second downlink MIMO communications signal wirelessly as a second electrical downlink MIMO communications signal over the second MIMO transmitter antenna in the second polarization;

the second MIMO transmitter configured to;

receive a third downlink MIMO communications signal in the first phase over a third downlink communications medium, and transmit the third downlink MIMO communications signal wirelessly as a third electrical downlink MIMO communications signal over the third MIMO transmitter antenna in the first polarization; and

receive a fourth downlink MIMO communications signal over a fourth downlink communications medium, and transmit the fourth downlink MIMO communications signal in a second phase shifted from the first phase, wirelessly as a fourth electrical downlink MIMO communications signal over the fourth MIMO transmitter antenna in the second polarization.

2. The remote unit of claim 1, wherein:

the first MIMO transmitter is further configured to transmit the first and second downlink MIMO communications signals wirelessly to a line-of-sight (LOS) wireless client; and

the second MIMO transmitter is configured to transmit the third and fourth downlink MIMO communications signals wirelessly to a line-of-sight (LOS) wireless client.

3. The remote unit of claim 1, further comprising at least one phase shifter configured to phase shift the fourth downlink MIMO communications signal in the second phase.

4. The remote unit of claim 1, wherein the second MIMO transmitter is configured to receive the fourth downlink MIMO communications signal in the second phase as a result of a phase shift of the fourth downlink MIMO communications signal in a central unit.

5. The remote unit of claim 1, wherein the second MIMO transmitter is configured to receive the fourth downlink MIMO communications signal in the second phase as a result of a phase shift of the fourth downlink MIMO communications signal in the fourth downlink communications medium.

6. The remote unit of claim 1, wherein the third MIMO transmitter antenna is phase offset from the fourth MIMO transmitter antenna.

7. The remote unit of claim 5, wherein the third MIMO transmitter antenna is phase offset from the fourth MIMO transmitter antenna by the third MIMO transmitter antenna being position offset from the fourth MIMO transmitter antenna.

8. The remote unit of claim 1, wherein the first MIMO transmitter is position offset from the second MIMO transmitter.

9. The remote unit of claim 1, wherein:

the first downlink MIMO communications signal further comprises a first optical downlink MIMO communications signal;

the second downlink MIMO communications signal further comprises a second optical downlink MIMO communications signal;

the third downlink MIMO communications signal further comprises a third optical downlink MIMO communications signal; and

the fourth downlink MIMO communications signal further comprises a fourth optical downlink MIMO communications signal.

10. The remote unit of claim 9, wherein

the first MIMO transmitter further comprises:

a first optical-to-electrical (O/E) converter configured to convert the first optical downlink MIMO communications signal to the first electrical downlink MIMO communications signal; and

a second optical-to-electrical (O/E) converter configured to convert the second optical downlink MIMO communications signal to the second electrical MIMO downlink communications signal; and

the second MIMO transmitter further comprises;

a third optical-to-electrical (O/E) converter configured to convert the third optical downlink MIMO communications signal to the third electrical downlink MIMO communications signal; and

a fourth optical-to-electrical (O/E) converter configured to convert the fourth optical downlink MIMO communications signal to the second electrical downlink MIMO communications signal

11. The remote unit of claim 1, wherein at least one of the first electrical downlink MIMO communications signal, the second electrical downlink MIMO communications signal, the third electrical downlink MIMO communications signal, and the fourth electrical downlink MIMO communications signal include a carrier frequency having an extremely high frequency (EHF) between approximately 30 GHz and approximately 300 GHz.

12. A method of transmitting MIMO communications signals to wireless client devices in a distributed antenna system, comprising:

receiving a first downlink MIMO communications signal in a first phase over a first downlink communications medium;

transmitting the first downlink MIMO communications signal wirelessly as a first electrical downlink MIMO communications signal over a first MIMO transmitter antenna in a first polarization; and

receiving a second downlink MIMO communications signal in the first phase over a second downlink communications medium;

transmitting the second downlink MIMO communications signal wirelessly as a second electrical downlink MIMO communications signal over a second MIMO transmitter antenna in a second polarization;

receiving a third downlink MIMO communications signal in the first phase over a third downlink communications medium;

transmitting the third downlink MIMO communications signal wirelessly as a third electrical downlink MIMO communications signal over a third MIMO transmitter antenna in the first polarization;

receiving a fourth downlink MIMO communications signal over a fourth downlink communications medium; and

transmitting the fourth downlink MIMO communications signal in a second phase shifted from the first phase, wirelessly as a fourth electrical downlink MIMO communications signal over a fourth MIMO transmitter antenna in the second polarization.

13. The method of claim 12, further comprising:

transmitting the first downlink MIMO communications signal wirelessly to a line-of-sight (LOS) wireless client;

transmitting the second downlink MIMO communications signal wirelessly to a line-of-sight (LOS) wireless client;

transmitting the third downlink MIMO communications signal wirelessly to a line-of-sight (LOS) wireless client; and

transmitting the fourth downlink MIMO communications signal wirelessly to a line-of-sight (LOS) wireless client.

14. The method of claim 12, further comprising phase shifting the fourth downlink MIMO communications signal in the second phase.

15. The method of claim 14, further comprising receiving the fourth downlink MIMO communications signal in the second phase shifted from the first phase in a central unit.

16. The method of claim 14, further comprising receiving the fourth downlink MIMO communications signal in the second phase shifted from the first phase in the fourth downlink communications medium.

17. The method of claim 14, comprising phase shifting the fourth downlink MIMO communications signal in the second phase in the second MIMO transmitter.

18. The method of claim 12, comprising phase offsetting the third MIMO transmitter antenna from the fourth MIMO transmitter antenna to phase shift the fourth downlink MIMO communications signal in the second phase.

19. The method of claim 18, further comprising phase offsetting the third MIMO transmitter antenna from the fourth MIMO transmitter antenna by position offsetting the third MIMO transmitter antenna from the fourth MIMO transmitter antenna.

20. The method of claim 12, further comprising position offsetting the first MIMO transmitter from the second MIMO transmitter to phase shift the fourth downlink MIMO communications signal in the second phase.

21. A distributed antenna system for distributing MIMO communications signals to wireless client devices, comprising:

a central unit comprising a central unit transmitter configured to receive a downlink communications signal, and transmit the received downlink communications signal as a first downlink MIMO communications signal over a first downlink communications medium, a second downlink MIMO communications signal over a second downlink communications medium, a third downlink MIMO communications signal over a third downlink communications medium, and a fourth downlink MIMO communications signal over a fourth downlink communications medium; and

a remote unit, comprising;

a first MIMO transmitter comprising a first MIMO transmitter antenna configured to transmit MIMO communications signals in a first polarization and a second MIMO transmitter antenna configured to transmit MIMO communications signals in a second polarization different from the first polarization;

a second MIMO transmitter comprising a third MIMO transmitter antenna configured to transmit MIMO communications signals in the first polarization and a fourth MIMO transmitter antenna configured to transmit MIMO communications signals in the second polarization;

the first MIMO transmitter configured to;

receive a first downlink MIMO communications signal in a first phase over a first downlink communications medium, and transmit the first downlink MIMO communications signal wirelessly as a first electrical downlink MIMO communications signal over the first MIMO transmitter antenna in the first polarization; and

receive a second downlink MIMO communications signal in the first phase over a second downlink communications medium, and transmit the second downlink MIMO communications signal wirelessly as a second electrical downlink MIMO communications signal over the second MIMO transmitter antenna in the second polarization;

the second MIMO transmitter configured to;

receive a third downlink MIMO communications signal in the first phase over a third downlink communications medium, and transmit the third downlink MIMO communications signal wirelessly as a third electrical downlink MIMO communications signal over the third MIMO transmitter antenna in the first polarization; and

receive a fourth downlink MIMO communications signal over a fourth downlink communications medium, and transmit the fourth downlink MIMO communications signal in a second phase shifted from the first phase, wirelessly as a fourth electrical downlink MIMO communications signal over the fourth MIMO transmitter antenna in the second polarization; and

at least one phase shifter configured to phase shift the fourth downlink MIMO communications signal to the second phase.

22. The distributed antenna system of claim 21, wherein:

the first MIMO transmitter is further configured to transmit the first and second downlink MIMO communications signals wirelessly to a line-of-sight (LOS) wireless client; and

the second MIMO transmitter is configured to transmit the third and fourth downlink MIMO communications signals wirelessly to a line-of-sight (LOS) wireless client.

23. The distributed antenna system of claim 21, wherein the central unit further comprises one or more electrical-to-optical (E/O) converters configured to:

convert the first downlink MIMO communications signal into a first optical downlink MIMO communications signal;

convert the second downlink MIMO communications signal into a second optical downlink MIMO communications signal;

convert the third downlink MIMO communications signal into a third optical downlink MIMO communications signal; and

convert the fourth downlink MIMO communications signal into a fourth optical downlink MIMO communications signal.