Reducing beamforming power consumption in a wireless communications system (WCS)
Reducing beamforming power consumption in a wireless communications system (WCS) is disclosed. In the WCS, a wireless node(s) is configured to emit a data-bearing radio frequency (RF) beam(s) in an intended direction(s). Specifically, the wireless node(s) is configured to form the data-bearing RF beam(s) by preprocessing a data signal based on a beamforming codeword to generate multiple beamforming signals, amplifying the beamforming signals to certain output powers using multiple power amplifiers, and emitting the amplified beamforming signals simultaneously from multiple antenna elements. In embodiments disclosed herein, the wireless node(s) can be configured to suppress a sidelobe(s) associated with the data-bearing RF beam(s) without sacrificing efficiency and/or increasing power consumption of the power amplifiers. As a result, the wireless node(s) can achieve improved adjacent channel power ratio (ACPR), adjacent channel leakage ratio (ACLR), and/or error vector magnitude (EVM) concurrent to reducing beamforming power consumption.
1 . A wireless node, comprising:
a power management circuit configured to generate a plurality of bias voltages based on a bias voltage control signal; a plurality of power amplifiers each configured to amplify a respective one of a plurality of beamforming signals based on a respective one of the plurality of bias voltages;
a beamforming processing circuit configured to generate the plurality of beamforming signals from a data signal based on a selected beamforming codeword, wherein the beamforming processing circuit is one of an analog beamforming circuit, a digital beamforming circuit, and a hybrid beamforming circuit; and
a codeword processing circuit configured to:
receive a suggested beamforming codeword for forming the plurality of beamforming signals; and
determine the selected beamforming codeword and the bias voltage control signal based on the suggested beamforming codeword.
2 . The wireless node of claim 1 , wherein the codeword processing circuit is further configured to:
determine the selected beamforming codeword to be identical to the suggested beamforming codeword in response to the suggested beamforming codeword being within a preconfigured capability of the wireless node; and
determine the selected beamforming codeword to be one of a plurality of predefined beamforming codewords that is closest to the suggested beamforming codeword in response to the suggested beamforming codeword being beyond the preconfigured capability of the wireless node.
3 . The wireless node of claim 1 , wherein the codeword processing circuit is further configured to:
determine from the suggested beamforming codeword that each of a subset of the plurality of power amplifiers is required to amplify a respective one of a subset of the plurality of beamforming signals to a respective reduced power level; and
generate the bias voltage control signal to cause the power management circuit to reduce a subset of the plurality of bias voltages received by the subset of the plurality of power amplifiers, respectively.
4 . The wireless node of claim 3 , wherein:
each of the plurality of power amplifiers is a class AB power amplifier configured to amplify the respective one of the plurality of beamforming signals; and
the power management circuit is further configured to reduce the subset of the plurality of bias voltages received by the subset of the plurality of power amplifiers.
5 . The wireless node of claim 3 , wherein:
each of the plurality of power amplifiers is a Doherty power amplifier comprising a carrier amplifier and a peaking amplifier configured to collectively amplify the respective one of the plurality of beamforming signals; and
the power management circuit is further configured to reduce the subset of the plurality of bias voltages received by the peaking amplifier in the subset of the plurality of power amplifiers.
6 . The wireless node of claim 3 , wherein:
each of the plurality of beamforming signals is modulated into a plurality of time-division multiplexing (TDD) frames each comprising a downlink subframe and an uplink subframe separated by a guard time; and
the power management circuit is further configured to reduce the subset of the plurality of bias voltages during the uplink subframe in a respective one of the plurality of TDD frames associated with a respective one of the subset of the plurality of beamforming signals.
7 . The wireless node of claim 1 , further comprising an antenna array that includes multiple antenna elements, each antenna element coupled to a respective one of the plurality of power amplifiers, and the antenna elements configured to simultaneously emit the plurality of beamforming signals to thereby form a radio frequency (RF) beam.
8 . A method for reducing beamforming power consumption in a wireless communications system (WCS), comprising:
generating a plurality of bias voltages based on a bias voltage control signal;
amplifying a plurality of beamforming signals based on the plurality of bias voltages, respectively;
generating the plurality of beamforming signals from a data signal based on a selected beamforming codeword, wherein generating the plurality of beamforming signals from the data signal is performed by a beamforming processing circuit comprising one of an analog beamforming circuit, a digital beamforming circuit, and a hybrid beamforming circuit;
receiving a suggested beamforming codeword for forming the plurality of beamforming signals; and
determining the selected beamforming codeword and the bias voltage control signal based on the suggested beamforming codeword.
9 . The method of claim 8 , further comprising:
determining the selected beamforming codeword to be identical to the suggested beamforming codeword in response to the suggested beamforming codeword being within a preconfigured capability of a wireless node; and
determining the selected beamforming codeword to be one of a plurality of predefined beamforming codewords that is closest to the suggested beamforming codeword in response to the suggested beamforming codeword being beyond the preconfigured capability of the wireless node.
10 . The method of claim 8 , further comprising:
determining from the suggested beamforming codeword that each of a subset of a plurality of power amplifiers is required to amplify a respective one of a subset of the plurality of beamforming signals to a respective reduced power level; and
generating the bias voltage control signal to cause a power management circuit to reduce a subset of the plurality of bias voltages received by the subset of the plurality of power amplifiers, respectively.
11 . The method of claim 10 , further comprising:
modulating each of the plurality of beamforming signals into a plurality of time-division multiplexing (TDD) frames each comprising a downlink subframe and an uplink subframe separated by a guard time; and
reducing the subset of the plurality of bias voltages during the uplink subframe in a respective one of the plurality of TDD frames associated with a respective one of the subset of the plurality of beamforming signals.
12 . A wireless communications system (WCS), comprising:
a distribution unit configured to distribute a plurality of data signals; and
a plurality of wireless nodes coupled to the distribution unit, wherein each of the plurality of wireless nodes comprises:
a power management circuit configured to generate a plurality of bias voltages based on a bias voltage control signal;
a plurality of power amplifiers each configured to amplify a respective one of a plurality of beamforming signals based on a respective one of the plurality of bias voltages;
a beamforming processing circuit configured to generate the plurality of beamforming signals from a respective one of the plurality of data signals based on a selected beamforming codeword, wherein the beamforming processing circuit is one of an analog beamforming circuit, a digital beamforming circuit, and a hybrid beamforming circuit; and
a codeword processing circuit configured to:
receive a suggested beamforming codeword for forming the plurality of beamforming signals; and
determine the selected beamforming codeword and the bias voltage control signal based on the suggested beamforming codeword.
13 . The WCS of claim 12 , wherein the distribution unit is further configured to determine and provide the suggested beamforming codeword to each of the plurality of wireless nodes periodically.
14 . The WCS of claim 13 , wherein the distribution unit is further configured to provide the suggested beamforming codeword and the respective one of the plurality of data signals to each of the plurality of wireless nodes concurrently.
15 . The WCS of claim 12 , wherein the codeword processing circuit is further configured to:
determine the selected beamforming codeword to be identical to the suggested beamforming codeword in response to the suggested beamforming codeword being within a preconfigured capability of a respective one of the plurality of wireless nodes; and
determine the selected beamforming codeword to be one of a plurality of predefined beamforming codewords that is closest to the suggested beamforming codeword in response to the suggested beamforming codeword being beyond the preconfigured capability of the respective one of the plurality of wireless nodes.
16 . The WCS of claim 12 , wherein the codeword processing circuit is further configured to:
determine from the suggested beamforming codeword that each of a subset of the plurality of power amplifiers is required to amplify a respective one of a subset of the plurality of beamforming signals to a respective reduced power level; and
generate the bias voltage control signal to cause the power management circuit to reduce a subset of the plurality of bias voltages received by the subset of the plurality of power amplifiers, respectively.
17 . The WCS of claim 16 , wherein:
each of the plurality of beamforming signals is modulated into a plurality of time-division multiplexing (TDD) frames each comprising a downlink subframe and an uplink subframe separated by a guard time; and
the power management circuit is further configured to reduce the subset of the plurality of bias voltages during the uplink subframe in a respective one of the plurality of TDD frames associated with a respective one of the subset of the plurality of beamforming signals.
18 . The WCS of claim 12 , wherein the distribution unit is configured to control radiation direction and/or amplitude of a respective radio frequency (RF) beam emitted by each of the plurality of wireless nodes via a suggested beamforming codeword, and to transmit the suggested beamforming codeword either concurrent to or independent from transmitting a respective one of the plurality of data signals, and to determine the suggested beamforming codeword periodically.
19 . The WCS of claim 12 , further comprising:
a digital routing unit coupled to the distribution unit; and a plurality of remote units coupled to the digital routing unit via a plurality of optical fiber-based communications mediums.
20 . The WCS of claim 19 , wherein:
the digital routing unit comprises: an electrical-to-optical (E/O) converter configured to convert a plurality of downlink communications signals into a plurality of downlink optical communications signals, respectively; and
an optical-to-electrical (O/E) converter configured to convert a plurality of uplink optical communications signals into a plurality of uplink communications signals, respectively; and
the plurality of remote units each comprises: a respective O/E converter configured to convert a respective one of the plurality of downlink optical communications signals into a respective one of the plurality of downlink communications signals; and
a respective E/O converter configured to convert a respective one of the plurality of uplink communications signals into a respective one of the plurality of uplink optical communications signals.