Distributed Antenna System for MIMO Technologies

• US 20080232305A1
• Filed: 12/17/2007
• Published: 09/25/2008
• Est. Priority Date: 12/19/2006
• Status: Active Grant

• Current Assignee: Corning Optical Communications LLC (Corning Incorporated)
• Original Assignee: Corning Optical Communications Wireless Ltd. (Corning Incorporated)
• Inventors: Oren, Yair, Saban, Ofer, Berlin, Igor, Shapira, Isaac, Reuven, Rami
• Granted Patent: US 8,873,585 B2
• Time in Patent Office: Days
• US Class Current: 370/328
• CPC Class Codes: H04B 1/40 Circuits
• CPC Class Codes: H04B 10/271 Combination of different networks, e.g. star and ring configuration in the same network or two ring networks interconnected
• 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 7/0602 using antenna switching H04B7/0686 takes precedence; antenna beam directivity switching H01Q3/24

Abstract

The invention is directed to a method and system for supporting MIMO technologies which can require the transport of multiple spatial streams on a traditional Distributed Antenna System (DAS). According to the invention, at one end of the DAS, each spatial stream is shifted in frequency to a pre-assigned band (such as a band at a frequency lower than the native frequency) that does not overlap the band assigned to other spatial streams (or the band of any other services being carried by the DAS). Each of the spatial streams can be combined and transmitted as a combined signal over a common coaxial cable. At the other “end” of the DAS, the different streams are shifted back to their original (overlapping) frequencies but retain their individual “identities” by being radiated through physically separate antenna elements.

Claims

1. A distributed antenna system comprising:

a radio interface unit adapted to receive a plurality of downlink spatial streams from at least one base station, the radio interface unit including at least one mixer adapted for converting each of the spatial streams from a native frequency band to a different, non-overlapping frequency band and a downlink duplexer adapted for combining each of the spatial streams to form a combined downlink signal on to a common transmission medium;

a base unit adapted to receive the combined downlink signal over the common transmission medium, and for transmitting the combined downlink signal to a plurality of remote units over a separate communication medium connecting the base unit to each remote unit;

each remote unit including a multiplexer adapted for connecting the remote unit with a plurality of antenna units and for transmitting the combined downlink signal to each of the antenna units over an antenna unit communication medium;

each antenna unit including a de-duplexer adapted for separating the combined downlink signal into each of the downlink spatial streams and at least one downlink mixer adapted for converting each of the downlink spatial streams to the native frequency band; and

a plurality of antennae coupled to each antenna unit, one for transmitting each of the downlink spatial streams.

2. A distributed antenna system according to claim 1, wherein the mixer in the radio interface unit converts each of the downlink spatial streams from the native frequency to a lower frequency band.

3. A distributed antenna system according to claim 1, wherein the base unit converts the combined downlink signal into an optical combined downlink signal and at least one of the separate communication media is an optical communication medium;

and

wherein at least one remote unit includes an optical communication medium interface for converting the optical downlink combined signal to the combined downlink signal.

4. A distributed antenna system according to claim 1, wherein at least one of the antenna unit communication media is a coaxial cable.

5. A distributed antenna system according to claim 1, wherein at least one of the plurality of antennae are adapted to receive a plurality of uplink spatial streams and wherein:

at least one of the antenna units further includes

an antenna time division duplexing switch adapted for switching the antenna connection between the uplink spatial stream and the downlink spatial stream,

at least one uplink mixer for converting each of the spatial streams from the native frequency to a different, non-overlapping frequency band,

an uplink duplexer adapted for combining each of the spatial streams to form a combined uplink signal; and

a first time division duplexing switch, coupled to the at least one downlink mixer and the at least one uplink mixer and adapted for switching the combined uplink signal and the combined downlink signal for transfer over the antenna unit communication medium; and

at least one of the remote units further includes

a second time division duplexing switch adapted for switching the combined uplink signal and the combined downlink signal for transfer over the antenna unit communication medium.

6. A distributed antenna system according to claim 5, wherein the uplink mixer in the antennae unit converts each of the up spatial streams from the native frequency to a lower frequency band.

7. A distributed antenna system according to claim 5, wherein the base unit converts the combined downlink signal into an optical combined downlink signal, converts the optical combined uplink signal to the combined uplink signal and at least one of the separate communication media is an optical communication medium;

and

wherein at least one remote unit includes an optical communication medium interface for converting the optical downlink combined signal to the combined downlink signal and an optical communication medium interface for converting the optical combined uplink signal to the combined uplink signal.

8. A distributed antenna system according to claim 5, wherein at least one of the antenna unit communication media is a coaxial cable.

9. A distributed antenna system according to claim 1, wherein the radio interface unit is adapted to receive other signals associated with other services, the other services using different, non-overlapping frequency bands from those used to transfer the downlink spatial streams and

the radio interface unit is adapted to combine the other signals with the combined downlink signals and transfer the combined downlink and other signals to the base unit;

the base unit being adapted to receive the combined downlink and other signals over the common transmission medium, and for transmitting the combined downlink and other signals to a plurality of remote units over a separate communication medium connecting the base unit to each remote unit;

the remote unit being adapted to separate the other signals from the combined downlink and other signals, selectively combine the other signals with the combined downlink signal and for transferring the combined downlink and other signals to at least one of plurality of antenna units; and

at least one of the antenna units including a de-duplexer adapted for separating the other signals from the combined downlink and other signals and for transmitting the other signals through an associated antenna.

10. A distributed antenna system according to claim 1, wherein the radio interface unit receives a plurality of sets of spatial streams from a plurality of base stations, at least one set of spatial streams associated with an antenna unit or a sector comprised of a plurality of antenna units, the remote unit further comprising a switch for selectively connecting one of said plurality of sets of spatial streams to one of a plurality of switch blocks, each switch block including a mixer adapted to convert each of the spatial streams in the combined downlink signal to a common set of frequency bands used to transfer signals to each of the associated antenna units and a multiplexer adapted to connect the combined downlink signals from each switch block to a predefined antenna unit or group of antenna units associated with a sector.

11. A method for conveying a plurality of spatial streams over a distributed antenna system comprising

receiving from a base station, each spatial stream having a native frequency;

converting each of the spatial streams from the native frequency to a different, non-overlapping frequency band;

combining each of the spatial streams to form a combined downlink signal;

transmitting the combined downlink signal to a base unit;

transmitting the combined downlink signal to a plurality of remote units over a separate communication medium connecting the base unit to each remote unit;

providing a multiplexer adapted for connecting the remote unit with a plurality of antenna units and transmitting the combined downlink signal to each of the antenna units over an antenna unit communication medium;

separating the combined downlink signal into each of the downlink spatial streams converting each of the downlink spatial streams to the native frequency band; and

transmitting each of the downlink spatial streams through an associated antenna.

12. A method according to claim 11 wherein spatial streams are converted from the native frequency band to a lower frequency band.

13. A method according to claim 11, further comprising

converting the combined downlink signal into an optical combined downlink signal and transmitting the optical combined downlink signal over the least one of the separate communication media which is an optical communication medium;

and

providing an optical communication medium interface at the remote unit for converting the optical downlink combined signal to the combined downlink signal.

14. A method according to claim 11, wherein at least one of the antenna unit communication media is a coaxial cable.

15. A method according to claim 11 further comprising:

receiving at one of the antennae, a plurality of uplink spatial streams;

switching the antenna connection between the uplink spatial stream and the downlink spatial stream to receive each uplink spatial stream;

converting each of the uplink spatial streams from the native frequency band to a different, non-overlapping frequency band,

combining each of the uplink spatial streams to form a combined uplink signal; and

switching the combined downlink signal and the combined uplink signal for transfer of both signals over the antenna unit communication medium;

separating the combined uplink signal into each of the uplink spatial streams;

converting each the uplink spatial streams to the native frequency band; and

transferring each of the uplink spatial streams to the base station.

16. A method according to claim 15, wherein spatial streams are converted from the native frequency band to a lower frequency band.

17. A method according to claim 15, further comprising

converting the combined downlink signal into an optical combined downlink signal and transmitting the optical combined downlink signal over the at least one of the separate communication media which is an optical communication medium;

converting the combined uplink optical signal received over the at least one of the separate communication media which is an optical communication medium into a combined uplink signal and transmitting the combined uplink signal to the base unit; and

providing an optical communication medium interface at the remote unit for converting the optical downlink combined signal to the combined downlink signal and an optical communication medium interface at the remote unit for converting the combined uplink signal to an optical combined uplink signal.

18. A method according to claim 15, wherein at least one of the antenna unit communication media is a coaxial cable.

19. A method according to claim 11, further comprising:

receiving other signals associated with other services, the other services using different, non-overlapping frequency bands from those used to transfer the downlink spatial streams;

combining the other signals with the combined downlink signals and transferring the combined downlink and other signals to the base unit;

receiving at the base unit, the combined downlink and other signals over the common transmission medium;

transmitting the combined downlink and other signals to a plurality of remote units over a separate communication medium connecting the base unit to each remote unit;

separating the other signals from the combined downlink and other signals,

selectively combining the other signals with the combined downlink signal;

transferring the combined downlink and other signals to at least one of plurality of antenna units;

separating the other signals from the combined downlink and other signals; and

transmitting the other signals through an associated antenna.

20. A method according to claim 11, further comprising:

receiving a plurality of sets of spatial streams from a plurality of base stations, at least one set of spatial streams associated with an antenna unit or a sector comprised of a plurality of antenna units,

selectively connecting one of said plurality of sets of spatial streams to one of a plurality of switch blocks;

each switch block converting each of the spatial streams in the combined downlink signal to a common set of frequency bands used to transfer signals to each of the associated antenna units;

connecting the combined downlink signals from each switch block to a predefined antenna unit or group of antenna units associated with a sector.