Radio-over-fiber (RoF) wireless picocellular system with combined picocells
View Patent ↗A radio-over-fiber (RoF) wireless picocellular system adapted to form an array of substantially non-overlapping individual picocells by operating adjacent picocells at different frequencies is operated to form one or more combined picocells. The combined picocells are formed from two or more neighboring picocells by the central head-end station operating neighboring picocells at a common frequency. Communication between the central head-end station and a client device residing within a combined picocell is enhanced by the availability of two or more transponder antenna systems. Thus, enhanced communication techniques such as antenna diversity, phased-array antenna networks and multiple-input/multiple-output (MIMO) methods can be implemented to provide the system with enhanced performance capability. These techniques are preferably implemented at the central head-end station to avoid having to make substantial changes to the wireless picocellular system infrastructure.
1. A centralized optical-fiber-based wireless picocellular system for wirelessly communicating with at least one client device, comprising:
a central head-end station adapted to provide radio-frequency (RF) signals;
two or more transponders optically coupled to the central head-end station via one or more optical fiber RF communication links, with the two or more transponders adapted to convert electrical signals to optical signals and vice versa and having an antenna system that forms a corresponding picocell based on said RF signals, wherein adjacent picocells formed from RF signals having different frequencies do not substantially overlap; and
wherein the central head-end station is adapted to provide one or more groups of two or more transponders with said RF signals having a common frequency within the transponder group so as to form corresponding one or more combined picocells.
2. The system of claim 1 , wherein the central head-end unit includes a diversity selector adapted to provide antenna diversity to at least one of the one or more combined picocells.
3. The system of claim 1 , wherein the central head-end unit is adapted to provide phases to the common-frequency RF signals provided to at least one of the one or more combined picocells so that the antenna systems of the transponders in the transponder group of the at least one combined picocell operate as a phased-array antenna network.
4. The system of claim 1 , wherein:
one or more of the at least one client devices and the central head-end station are adapted to perform multiple-input/multiple-output (MIMO) processing of the RF signals.
5. The system of claim 4 , wherein the central head-end station includes a service unit with MIMO signal processing capability.
6. The system of claim 5 , wherein the service unit includes a MIMO chip adapted to perform said MIMO signal processing.
7. In a centralized optical-fiber-based wireless picocellular system having a central head-end station, a method of combining two or more picocells that are substantially non-overlapping when operated at different radio-frequency (RF) frequencies, comprising:
operating a group of two or more neighboring picocells at a common RF frequency provided by the central head-end station to provide substantial overlap of said two or more neighboring picocells so as to form a combined picocell.
8. The method of claim 7 , including forming one or more additional groups of two or more neighboring picocells at other common frequencies so as to form multiple combined picocells.
9. The method of claim 8 , wherein neighboring combined picocells operate at a different common frequency.
10. The method of claim 7 , wherein a client device resides within the combined picocell and wherein the picocell has an associated transponder with an antenna system, the method further including:
communicating between the client device and the central head-end station using antenna diversity via the transponder antenna systems associated with the combined picocell.
11. The method of claim 7 , wherein a client device resides within the combined picocell and wherein the picocell has an associated transponder with an antenna system, the method further including:
communicating between the client device and the central head-end station by operating the transponder antenna systems associated with the combined picocell as a phased-array antenna network.
12. The method of claim 7 , wherein a client device having multiple antennas and adapted to communicate using multiple-input/multiple-output (MEMO) signal processing resides within the combined picocell and wherein the picocell has an associated transponder with an antenna system, the method further including:
communicating between the client device and the central head-end station using MIMO signal processing via the client device multiple antennas and the transponder antenna systems associated with the combined picocell.
13. A method of forming a combined picocell in a wireless picocellular system adapted to form individual picocells that do not substantially overlap when operated at different frequencies, with the individual picocells associated with a transponder optically coupled to a central head-end station and having an antenna system, the method comprising:
a) providing at the central head-end station a downlink radio-frequency (RF) signal; and
b) either simultaneously or non-simultaneously sending the downlink RF signal to corresponding two or more neighboring transponders at a common frequency so that said two or more neighboring transponders substantially overlap to form a combined picocell.
14. The method of claim 13 , including performing acts a) and b) for different common frequencies and for different two or more neighboring transponders so as to form multiple combined picocells.
15. The method of claim 13 , wherein a client device resides within the combined picocell and wherein the antenna has an associated received signal strength as measured at the central head-end station, the method further including:
communicating between the client device and the central head-end station using antenna diversity via the transponder antenna systems associated with the combined picocell by having the central head-end station communicate with the transponder having the greatest received signal strength.
16. The method of claim 15 , including operably providing the central head-end station with a diversity selector.
17. The method of claim 13 , wherein a client device resides within the combined picocell, and further including:
communicating between the client device and the central head-end station by operating the transponder antenna systems associated with the combined picocell as a phased-array antenna network.
18. The method of claim 13 , wherein a client device having multiple antennas and adapted to communicate using multiple-input/multiple-output (MIMO) signal processing resides within the combined picocell, and further including:
communicating between the client device and the central head-end station using MIMO signal processing via the client device multiple antennas and the transponder antenna systems associated with the combined picocell.
19. The method of claim 18 , including operably providing the central head-end station with a MIMO chip adapted to perform said MIMO signal processing.
20. The method of claim 19 , including operating the MIMO chip to cause the downlink RF signal to be divided into multiple bit streams and providing the multiple bit streams to corresponding multiple transponder antenna systems associated with the combined picocell.