MIMO-ADAPTED DISTRIBUTED ANTENNA SYSTEM

• US 20080192855A1
• Filed: 02/06/2008
• Published: 08/14/2008
• Est. Priority Date: 02/12/2007
• Status: Active Grant

• Current Assignee: Corning Optical Communications LLC (Corning Incorporated)
• Original Assignee: Mobileaccess Networks Limited (Corning Incorporated)
• Inventors: Saban, Ofer, Harel, Dror, Shapira, Isaac, Holtzman, Yehuda
• Granted Patent: US 7,483,504 B2
• Time in Patent Office: Days
• US Class Current: 375/267
• CPC Class Codes: G01S 3/023 Monitoring or calibrating
• CPC Class Codes: G01S 5/04 Position of source determined by a plurality of spaced direction-finders
• CPC Class Codes: H04B 7/02 Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas RAKE receivers H04B1/7115
• 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 7/10 Polarisation diversity; Directional diversity
• CPC Class Codes: H04L 27/00 Modulated-carrier systems
• CPC Class Codes: H04L 27/125 using a controlled oscillator in an open loop
• CPC Class Codes: H04L 5/0035 Resource allocation in a cooperative multipoint environment
• CPC Class Codes: H04L 5/1469 using time-sharing

Abstract

Methods and systems for carrying different signals required for MIMO communication using a single coaxial cable between two endpoints of a distributed antenna system (DAS) network. Original MIMO signals having the same frequency are frequency-separated at a first endpoint of the network. The frequency-separated signals are propagated together over the single coaxial cable and then reconstructed to their original frequency at a second endpoint of the network.

Claims

1. A method for propagating multiple input multiple output (MIMO) over a distributed antenna system (DAS) network, comprising the steps of:

a) providing a plurality n of original MIMO signals;

b) at a first endpoint of the DAS network, frequency shifting n−

1 of the MIMO signals into signals with n−

1 separate frequencies, with one MIMO signal left un-shifted in frequency;

c) propagating the n−

1 frequency shifted signals and the un-shifted frequency signal together over a single coaxial cable extending for at least part of a path from the first endpoint to a second endpoint of the DAS network; and

d) at the second endpoint, reconstructing the original MIMO signals.

2. The method of claim 1, wherein the step of providing a plurality of n MIMO signals includes providing a plurality of MIMO signals belonging to a plurality of services.

3. The method of claim 1, wherein the first endpoint includes a master unit, wherein the second endpoint includes a remote unit and wherein the step of propagating includes propagating a reference frequency signal in addition to the n−

1 frequency-shifted signals and the un-shifted signal over the single co-axial cable.

4. The method of claim 3, further comprising the step of reconstructing includes reconstructing the original MIMO signal with the assistance of the reference frequency signal.

5. The method of claim 1, wherein the step of frequency shifting n−

1 of the MIMO signals into signals with n−

1 separate frequencies includes, for each of the n−

1 signals;

i) at the first endpoint, mixing the original signal with a mixing signal to create an intermediate frequency signal,

ii) at the second endpoint, mixing the intermediate frequency signal with a mixing signal of the same frequency to reconstruct the original signal.

6. The method of claim 1, wherein the first endpoint is a remote unit and wherein the second endpoint is a master unit.

7. The method of claim 5, wherein the mixing the original signal with a mixing signal includes:

A) monitoring the un-shifted signal to determine the frequency of a channel associated therewith,

B) generating the mixing signal based on the frequency of the associated channel, and

C) mixing the mixing signal based on the frequency of the associated channel with the original signal.

8. A method for propagating multiple input multiple output (MIMO) signals in a distributed antenna system (DAS) network, comprising the steps of:

a) providing a plurality of MIMO signals; and

b) propagating the plurality of MIMO signals over a single coaxial cable from one endpoint to another endpoint of the DAS network.

9. The method of claim 8, further comprising the steps of:

c) providing at least one non-MIMO signal; and

d) propagating the at least one non-MIMO signal together with the MIMO signals over the single coaxial cable from one endpoint to another endpoint of the DAS network.

10. The method of claim 8, wherein the step of propagating a plurality of MIMO signals includes propagating a plurality of MIMO signals belonging to a plurality of services.

11. The method of claim 8, wherein the step of providing a plurality of MIMO signals includes providing a plurality of original MIMO signals having respective original frequencies and wherein the step of propagating the plurality of MIMO signals over a single coaxial cable from one endpoint to another endpoint of the DAS network includes:

i) at the one endpoints frequency shifting all the original MIMO signals into signals with separate frequencies different from their respective original frequencies,

ii) propagating the frequency shifted signals over the single coaxial cable; and

iii) at the other endpoint, reconstructing each original MIMO signal.

12. The method of claim 11, wherein the frequency shifting all the original MIMO signals includes mixing each original signal f_r with a mixing signal f_m to create an intermediate frequency signal f_i, and wherein the reconstructing each original MIMO signal includes mixing each mixing signal f_m is with the intermediate frequency signal f_i.

13. The method of claim 12, wherein the propagating the frequency shifted signals over the single coaxial cable includes filtering the frequency shifted signals with a band pass filter.

14. The method of claim 8, wherein the step of providing a plurality of MIMO signals includes providing a plurality of original MIMO signals having respective original frequencies and wherein the step of propagating the plurality of MIMO signals over a single coaxial cable from one endpoint to another endpoint of the DAS network includes:

i) at the one endpoint, frequency shifting all the original MIMO signals except one into signals with separate frequencies different from their respective original frequencies,

ii) propagating the frequency shifted signals and the un-shifted frequency signal together over the single coaxial cable; and

iii) at the other endpoint, reconstructing each original MIMO signal.

15. The method of claim 14, wherein the frequency shifting all the original MIMO signals includes mixing each original signal f_r with a mixing signal f_m to create an intermediate frequency signal f_i, and wherein the reconstructing each original MIMO signal includes mixing each mixing signal f_m is with the intermediate frequency signal f_i

16. The method of claim 15, wherein the propagating the frequency shifted signals and the un-shifted frequency signal together over the single coaxial cable includes filtering the frequency shifted signals with a band pass filter.

17. A system for propagating a plurality of multiple input multiple output (MIMO) signals in a distributed antenna system (DAS) network, comprising:

a) a master unit and at least one remote unit, each unit having a frequency separation mechanism for separating same-frequency original MIMO signals into frequency-separated MIMO signals and a frequency reconstruction mechanism for reconstructing the same-frequency original MIMO signals from the frequency-separated MIMO signals; and

b) a single coaxial cable extending at least partially between the master unit and the at least one remote unit and used to propagate all the frequency-separated MIMO signals between the master unit and the at least one remote unit.

18. The system of claim 17, further comprising:

c) a frequency reference mechanism for assisting in the frequency reconstruction.

19. The system of claim 17, wherein each remote unit is coupled to at least one antenna of the DAS.

20. The system of claim 18, wherein each MIMO signal belongs to a MIMO service, the system further comprising a receiver which identifies an active channel of a given MIMO service and tunes the frequency down-shift and up-shift mechanism based on the frequency of the identified active channel.