Reducing location-dependent destructive interference in distributed antenna systems (DASS) operating in multiple-input, multiple-output (MIMO) configuration, and related components, systems, and methods

• US 9,525,472 B2
• Filed: 07/30/2014
• Issued: 12/20/2016
• Est. Priority Date: 07/30/2014
• Status: Active Grant

• Current Assignee: Corning Incorporated
• Original Assignee: Corning Incorporated
• Inventors: George, Jacob, Ng'Oma, Anthony, Yang, Hejie
• Primary Examiner(s): CURS, NATHAN M
• Application Number:
  US14/447,014
• Publication Number:
  US 20160036505A1
• Time in Patent Office: 874 Days
• US Class Current: 1/1
• CPC Class Codes: H04B 10/2575 Radio-over-fibre, e.g. radio frequency signal modulated onto an optical carrier
• 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 10/25891 Transmission components H04B10/40 takes precedence
• CPC Class Codes: H04B 7/022 Site diversity; Macro-diversity using two or more spaced independent antennas H04B7/04
• 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 7/10 Polarisation diversity; Directional diversity
• CPC Class Codes: H04W 72/51 based on terminal or device properties
• CPC Class Codes: H04W 72/541 using the level of interference
• CPC Class Codes: H04W 88/10 adapted for operation in multiple networks, e.g. multi-mode access points

Abstract

Components, systems, and methods for reducing location-dependent destructive 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 separation (i.e., phase, amplitude) in the received MIMO communications signals. Thus, to provide amplitude separation of received MIMO communications 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 amplitude adjusted in one of the polarization states to provide amplitude separation between received MIMO communications signals. In other embodiments, multiple transmitter antennas in a MIMO transmitter can be offset to provide amplitude separation.

Claims

1. A multiple-input, multiple-output (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;

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 at a first amplitude 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 at the first amplitude 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 at the first amplitude 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 at a second amplitude modified from the first amplitude, 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 downlink MIMO communications signal and second downlink MIMO communications signal wirelessly to a line-of-sight (LOS) wireless client; and

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

3. The remote unit of claim 1, further comprising at least one amplitude adjustment circuit configured to amplitude adjust the fourth downlink MIMO communications signal at the second amplitude.

4. The remote unit of claim 3, wherein the at least one amplitude adjustment circuit is further configured to be electronically tunable to adjust the fourth downlink MIMO communications signal at the second amplitude.

5. The remote unit of claim 3, wherein the amplitude adjustment circuit is configured to attenuate the fourth downlink MIMO communications signal at the second amplitude.

6. The remote unit of claim 3, wherein the amplitude adjustment circuit is configured to amplify the fourth downlink MIMO communications signal at the second amplitude.

7. The remote unit of claim 3, wherein the amplitude adjustment circuit is configured to adjust bias signal of a laser diode to provide amplitude adjustment.

8. The remote unit of claim 3, wherein the amplitude adjustment circuit is configured to adjust a bias signal of an optical modulator to amplitude adjust the fourth downlink MIMO communications signal at the second amplitude.

9. The remote unit of claim 1, wherein the second MIMO transmitter is configured to receive the fourth downlink MIMO communications signal at the second amplitude as a result of an amplitude adjustment of the fourth downlink MIMO communications signal in a central unit.

10. The remote unit of claim 1, wherein the second MIMO transmitter is configured to receive the fourth downlink MIMO communications signal in the second amplitude as a result of an amplitude adjustment of the fourth downlink MIMO communications signal in the fourth downlink communications medium.

11. 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.

12. The remote unit of claim 11, 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 fourth electrical downlink MIMO communications signal.

13. 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.

14. A method of transmitting multiple-input, multiple-output (MIMO) communications signals to wireless client devices in a distributed antenna system, comprising:

receiving a first downlink MIMO communications signal at a first amplitude 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 at the first amplitude 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 at the first amplitude 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 at a second amplitude modified from the first amplitude, wirelessly as a fourth electrical downlink MIMO communications signal over a fourth MIMO transmitter antenna in the second polarization.

15. The method of claim 14, 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.

16. The method of claim 14, further comprising amplitude adjusting the fourth downlink MIMO communications signal at the second amplitude.

17. The method of claim 16, further comprising receiving the fourth downlink MIMO communications signal at the second amplitude modified from the first amplitude in a central unit.

18. The method of claim 16, further comprising receiving the fourth downlink MIMO communications signal at the second amplitude modified from the first amplitude in the fourth downlink communications medium.

19. The method of claim 16, comprising amplitude adjusting the fourth downlink MIMO communications signal at the second amplitude in the second MIMO transmitter antenna.

20. A distributed antenna system for distributing multiple-input, multiple-output (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 at a first amplitude 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 at the first amplitude 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 at the first amplitude 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 at a second amplitude modified from the first amplitude, wirelessly as a fourth electrical downlink MIMO communications signal over the fourth MIMO transmitter antenna in the second polarization; and

at least one amplitude adjustment circuit configured to amplitude adjust the fourth downlink MIMO communications signal to the second amplitude.

21. The distributed antenna system of claim 20, wherein:

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

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

22. The distributed antenna system of claim 20, wherein the at least one amplitude adjustment circuit is disposed in the fourth downlink communications medium.