Antenna array beamforming in a remote unit(s) in a wireless distribution system (wds)

Abstract

Embodiments of the disclosure relate to antenna array beamforming in a remote unit(s) in a wireless distribution system (WDS). In this regard, a remote unit in a WDS includes an antenna array having a plurality of radio frequency (RF) antennas. The RF antennas transmit a plurality of modified downlink RF signals in a plurality of phases. A control circuit in the remote unit determines the phases to cause the RF antennas to transmit a formed radiation beam(s) in a radiation direction(s). The control circuit controls a plurality of phase shifters to generate the modified downlink RF signals in the phases. By supporting antenna array beamforming in the remote unit, it is possible to steer the formed radiation beam(s) according to a specific floor layout(s) to provide enhanced indoor RF coverage in the WDS. As a result, it may be possible to reduce deployment and/or installation costs of the WDS.

What is claimed is: 
     
         1 . A wireless distribution system (WDS), comprising:
 a central unit; and   a plurality of remote units configured to:
 receive a plurality of downlink electrical communications signals from the central unit; and 
 provide a plurality of uplink electrical communications signals to the central unit; 
   wherein one or more of the plurality of remote units each comprises:
 an antenna array comprising a plurality of radio frequency (RF) antennas configured to transmit a plurality of modified downlink RF signals in at least one formed radiation beam in at least one radiation direction; 
 a plurality of phase shifters configured to:
 phase-shift a plurality of downlink RF signals to generate the plurality of modified downlink RF signals in a plurality of phases, respectively; and 
 provide the plurality of modified downlink RF signals to the plurality of RF antennas in the antenna array; and 
 
 a control circuit configured to:
 determine the plurality of phases to cause the plurality of RF antennas to transmit the plurality of modified downlink RF signals in the at least one formed radiation beam in the at least one radiation direction; and 
 control the plurality of phase shifters to generate the plurality of modified downlink RF signals in the plurality of phases, respectively. 
 
   
     
     
         2 . The WDS of  claim 1 , wherein the antenna array comprises a plurality of omnidirectional RF antennas configured to transmit the plurality of modified downlink RF signals in the at least one formed radiation beam in the at least one radiation direction. 
     
     
         3 . The WDS of  claim 1 , wherein each of the plurality of phase shifters comprises:
 a first switched line phase shifter configured to phase-shift a respective downlink RF signal among the plurality of downlink RF signals by zero degrees (0°) or one hundred eighty degrees (180°) to generate a first intermediate downlink RF signal;   a reflective phase shifter configured to phase-shift the first intermediate downlink RF signal between zero degrees (0°) and ninety degrees (90°) to generate a second intermediate downlink RF signal; and   a second switched line phase shifter configured to phase-shift the second intermediate downlink RF signal by zero degrees (0°) or ninety degrees (90°) to generate a respective modified downlink RF signal among the plurality of modified downlink RF signals.   
     
     
         4 . The WDS of  claim 1 , wherein each of the one or more of the plurality of remote units further comprises:
 a duplexer circuit configured to receive a downlink RF communications signal among the plurality of downlink electrical communications signals corresponding to one or more downlink communications services and configured to be transmitted from the remote unit in a predetermined RF band; and   a splitter combiner configured to:
 split the downlink RF communications signal into the plurality of downlink RF signals; and 
 provide the plurality of downlink RF signals to the plurality of phase shifters, respectively. 
   
     
     
         5 . The WDS of  claim 4 , wherein:
 the plurality of RF antennas is further configured to receive a plurality of modified uplink RF signals, respectively;   the plurality of phase shifters is further configured to generate a plurality of uplink RF signals based on the plurality of modified uplink RF signals, respectively; and   the splitter combiner is further configured to:
 combine the plurality of uplink RF signals to generate an uplink RF communications signal associated with one or more uplink communications services; and 
 provide the uplink RF communications signal to the duplexer circuit to be transmitted to the central unit among the plurality of uplink electrical communications signals. 
   
     
     
         6 . The WDS of  claim 4 , wherein:
 X first RF antennas selected from the plurality of RF antennas are disposed uniformly on a first line, wherein each of the X first RF antennas is separated from an immediately adjacent first RF antenna by a predetermined distance; and   X-1 second RF antennas selected from the plurality of RF antennas are disposed uniformly on a second line located immediately adjacent to the first line and separated from the first line by a line separation distance, wherein each of the X-1 second RF antennas is separated from an immediately adjacent second RF antenna by the predetermined distance,   wherein X is an integer variable.   
     
     
         7 . The WDS of  claim 6 , wherein:
 X-1 third RF antennas selected from the plurality of RF antennas are disposed uniformly on a third line located immediately adjacent to the first line and separated from the first line by the line separation distance, wherein each of the X-1 third RF antennas is separated from an immediately adjacent third RF antenna by the predetermined distance;   X-2 fourth RF antennas selected from the plurality of RF antennas are disposed uniformly on a fourth line located immediately adjacent to the second line and separated from the second line by the line separation distance, wherein each of the X-2 fourth RF antennas is separated from an immediately adjacent fourth RF antenna by the predetermined distance; and   X-2 fifth RF antennas selected from the plurality of RF antennas are disposed uniformly on a fifth line located immediately adjacent to the third line and separated from the third line by the line separation distance, wherein each of the X-2 fifth RF antennas is separated from an immediately adjacent fifth RF antenna by the predetermined distance.   
     
     
         8 . The WDS of  claim 7 , wherein the predetermined distance equals one-half of a wavelength of a center frequency of the predetermined RF band. 
     
     
         9 . The WDS of  claim 4 , wherein:
 the antenna array comprises nineteen RF antennas configured to transmit nineteen modified downlink RF signals in the at least one formed radiation beam in the at least one radiation direction;   the plurality of phase shifters comprises nineteen phase shifters configured to:
 phase-shift nineteen downlink RF signals to generate the nineteen modified downlink RF signals in nineteen phases, respectively; and 
 provide the nineteen modified downlink RF signals to the nineteen RF antennas in the antenna array; and 
   the control circuit is configured to:
 determine the nineteen phases to cause the nineteen RF antennas to transmit the nineteen modified downlink RF signals in the at least one formed radiation beam in the at least one radiation direction; and 
 control the nineteen phase shifters to generate the nineteen modified downlink RF signals in the nineteen phases, respectively. 
   
     
     
         10 . The WDS of  claim 9 , wherein the splitter combiner comprises:
 a first three-way splitter configured to split the downlink RF communications signal having a determined power level to generate three first downlink RF signals, each having one-third of the determined power level;   three second two-way splitters each configured to split the three first downlink RF signals to generate nine second downlink RF signals, each having one-ninth of the determined power level;   eight two-way splitters configured to split eight of the nine second downlink RF signals to generate sixteen of the nineteen downlink RF signals, each having one-eighteenth (of the determined power level; and   a third three-way splitter configured to split one of the nine second downlink RF signals to generate three of the nineteen downlink RF signals, each having one-twenty-seventh of the determined power level.   
     
     
         11 . The WDS of  claim 10 , wherein the nineteen RF antennas in the antenna array are disposed in a circular-shaped area. 
     
     
         12 . The WDS of  claim 11 , wherein:
 one first selected RF antenna among the nineteen RF antennas is disposed at a center point of the circular-shaped area;   six second selected RF antennas among the nineteen RF antennas are disposed respectively at six first vertices of a first regular hexagon having a first radius extending from the center point of the circular-shaped area;   six third selected RF antennas among the nineteen RF antennas are disposed respectively at six second vertices of a second regular hexagon having a second radius extending from the center point of the circular-shaped area, wherein the second radius equals two times the first radius; and   six fourth selected RF antennas among the nineteen RF antennas are disposed respectively at six respective midpoints of six sides of the second regular hexagon.   
     
     
         13 . The WDS of  claim 12 , wherein three of the six second selected RF antennas disposed at the six first vertices of the first regular hexagon are configured to receive the three downlink RF signals having the one-twenty-seventh of the determined power level. 
     
     
         14 . The WDS of  claim 12 , wherein:
 the nineteen RF antennas are configured to transmit the nineteen modified downlink RF signals in the predetermined RF band; and   the first radius of the first regular hexagon equals one-half of a wavelength of a center frequency of the predetermined RF band.   
     
     
         15 . The WDS of  claim 14 , wherein each of the one or more of the plurality of remote units further comprises a second RF antenna configured to:
 transmit a second downlink RF communications signal in a second predetermined RF band located in a lower frequency spectrum than the predetermined RF band; and   receive a second uplink RF communications signal in the second predetermined RF band.   
     
     
         16 . The WDS of  claim 14 , wherein each of the one or more of the plurality of remote units further comprises:
 a plurality of second phase shifters configured to phase-shift a plurality of second downlink RF signals to generate a plurality of second modified downlink RF signals in a plurality of second phases, respectively;   a second splitter combiner configured to:
 split a second downlink RF communications signal into the plurality of second downlink RF signals; and 
 provide the plurality of second downlink RF signals to the plurality of second phase shifters, respectively; and 
   a plurality of multiple-input multiple-output (MIMO) splitter combiners configured to:
 receive the plurality of modified downlink RF signals from the plurality of phase shifters, respectively; 
 receive the plurality of second modified downlink RF signals from the plurality of second phase shifters, respectively; 
 generate a plurality of downlink MIMO signals based on the plurality of modified downlink RF signals and the plurality of second modified downlink RF signals, respectively; and 
 provide the plurality of downlink MIMO signals to the plurality of RF antennas in the antenna array. 
   
     
     
         17 . The WDS of  claim 2 , wherein the central unit comprises:
 an electrical-to-optical (E/O) converter configured to convert the plurality of downlink electrical communications signals into a plurality of downlink optical fiber-based communications signals, respectively; and   an optical-to-electrical (O/E) converter configured to convert a plurality of uplink optical fiber-based communications signals into the plurality of uplink electrical communications signals, respectively.   
     
     
         18 . The WDS of  claim 17 , wherein the plurality of remote units comprises:
 a plurality of remote unit O/E converters configured to convert the plurality of downlink optical fiber-based communications signals into the plurality of downlink electrical communications signals, respectively; and   a plurality of remote unit E/O converters configured to convert the plurality of uplink electrical communications signals into the plurality of uplink optical fiber-based communications signals, respectively.   
     
     
         19 . The WDS of  claim 1 , wherein the central unit comprises:
 an electrical-to-optical (E/O) converter configured to convert the plurality of downlink electrical communications signals into a plurality of downlink optical fiber-based communications signals, respectively; and   an optical-to-electrical (O/E) converter configured to convert a plurality of uplink optical fiber-based communications signals into the plurality of uplink electrical communications signals, respectively.   
     
     
         20 . The WDS of  claim 19 , the plurality of remote units comprises:
 a plurality of remote unit O/E converters configured to convert the plurality of downlink optical fiber-based communications signals into the plurality of downlink electrical communications signals, respectively; and   a plurality of remote unit E/O converters configured to convert the plurality of uplink electrical communications signals into the plurality of uplink optical fiber-based communications signals, respectively.