Beam steering antenna transmitter, multi-user antenna mimo transmitter and related methods of communication
An transmitter to be used in wireless multi-user MIMO has been described above. The system combines the virtues of digital, analog and optical processing to arrive at a solution for scalable, non-blocking, simultaneous transmission to multiple UE-s. The system architecture is independent of the RF carrier frequency, and different frequency bands can be accessed easily and rapidly by tuning the optical source (TOPS). The data channels are established in the digital domain and the RF beam-forming accuracy is only limited by the available resolution of DAC, which can be as high as 16 bits for 2.8 GSPS in off-the-shelf components.
1 . A An antenna array transmitter, comprising:
a first a tunable optical paired source configured to generate a first optical beam having a first wavelength, and a second optical beam having a second wavelength, and configured to combine the first optical beam and the second optical beam into a combined orthogonally polarized optical beam comprising the first optical beam polarized along a first axis and the second optical beam polarized along a second axis, perpendicular to the first axis;
M vector modulators, where M is an integer a positive integer greater than one, each vector modulator having an optical input and an optical signal output, the M vector modulators including a first vector modulator, the first vector modulator comprising:
an electro-optical phase modulator having an input to receive the combined orthogonally polarized optical beam, the electro-optical phase modulator configured to phase modulate the combined orthogonally polarized optical beam in response to a first analog electrical signal;
a polarizer configured to receive the phase modulated combined orthogonally polarized optical beam and to project the first optical beam and the second optical beam components of the combined orthogonally polarized optical beam onto the same axis to form a combined linearly polarized optical beam;
an electro-optical amplitude modulator having an input to receive the combined linearly polarized optical beam in response to a second analog electrical signal;
M photodetectors coupled to receive an optical input from a corresponding one of the M vector modulators and output a corresponding electrical signal, the M photodetectors including a first photodetector coupled to receive the amplitude modulated linearly polarized optical beam from the electro-optical amplitude modulator of the first vector modulator; and
M antennas each electrically coupled to a respective one of the photodetectors to receive a driving signal corresponding to the electrical signal output by the respective photodetector.
2 . The transmitter of claim 1 , wherein
wherein the M antennas are each directly electrically coupled to the respective one of the photodetectors to receive the electrical signal output by the corresponding photodetector as the driving signal.
3 . The transmitter of claim 1 , wherein each of the M vector modulators is configured to receive the combined orthogonally polarized optical beam provided by the first a tunable optical paired source.
4 . The transmitter of claim 3 , wherein each of the M vector modulators comprise corresponding structure of the first vector modulator, including the electro-optical phase modulator, the polarizer and the electro-optical amplitude modulator.
5 . The transmitter of claim 1 , further comprising:
a plurality of tunable optical paired sources, including the first tunable optical paired source, each of the plurality of tunable optical paired sources configured to generate a corresponding combined orthogonally polarized optical beam to be transmitted to different vector modulators.
6 . The transmitter of claim 5 , further comprising an oscillator configured to generate an RF reference signal, wherein the plurality of tunable optical paired sources are connected to receive the RF reference signal.
7 . The transmitter of claim 6 , wherein oscillator is a voltage controlled oscillator, and wherein the RF reference signal output by the oscillator has a frequency that is controlled by a voltage input to the voltage controlled oscillator.
8 . The transmitter of claim 1 ,
wherein the tunable optical paired sources comprises an oscillator configured to generate an RF reference signal,
wherein a difference of the first wavelength of the first optical beam and the second wavelength of a second optical beam is controlled by the RF reference signal.
9 . The transmitter of claim 8 , wherein the oscillator is a voltage controlled oscillator, and wherein the RF reference signal output by the oscillator has a frequency that is controlled by a voltage input to the voltage controlled oscillator.
10 . The transmitter of claim 8 , wherein frequencies of electromagnetic waves output by the M antennas are responsive to the RF reference signal.
11 . The transmitter of claim 8 ,
wherein the RF signal has a first frequency, and
wherein the amplitude modulated linearly polarized optical beam output by the electro-optical amplitude modulator of the first vector modulator has a beat frequency that is substantially the same as the first frequency of the RF signal.
12 . The transmitter of claim 8 ,
wherein the RF signal has a first frequency, and
wherein the amplitude modulated linearly polarized optical beam output by the electro-optical amplitude modulator of the first vector modulator has a beat frequency equal to the first frequency of the RF signal offset by the frequency of at least one of the first analog electrical signal and the second analog electrical signal.
13 . The transmitter of claim 1 , further comprising:
a digital encoder configured to receive N streams of data symbols and a channel state matrix comprised of a plurality of columns of channel state complex vectors, the digital encoder configured to output M pairs of digital values as a function of the data symbols and the channel state matrix; and
M pairs of digital to analog converters configured to generate M analog electrical signal pairs by performing an digital to analog conversion on corresponding ones of M pairs of digital values or corresponding ones of second pairs of digital values derived from the M pairs of digital values.
14 . The transmitter of claim 13 ,
wherein each of the M vector modulators comprise a pair of inputs connected to receive a corresponding one of the M analog electrical signal pairs.
15 . The transmitter of claim 13 ,
wherein the digital encoder further comprises M pairs of modulators to upconvert corresponding pairs of the M analog electrical signal pairs to provide M upconverted electrical signal pairs, and
wherein each of the M vector modulators comprise a pair of inputs connected to receive a corresponding one of the M upconverted analog electrical signal pairs.
16 . The transmitter of claim 13 , wherein each of the channel state complex vectors corresponds to an RF beam output by the M antennas, each RF beam forming a communication channel to transmit information to at least one location where the corresponding RF beam converges.
17 . A method of transmitting information, comprising:
generating M combined orthogonally polarized optical beams, where M is an integer a positive integer greater than one and the M combined orthogonally polarized optical beams comprise a first optical beam polarized along a first axis and a second optical beam polarized along a second axis, perpendicular to the first axis, the first optical beam having a first wavelength and the second optical beam having a second optical beam perpendicular to the first optical beam;
phase modulating each of the M combined orthogonally polarized optical beams;
converting each of the M phase modulated combined orthogonally polarized optical beams to corresponding M linearly polarized optical beams by including projecting the first optical beam and the second optical beam components of each of the phase modulated combined orthogonally polarized optical beams onto a corresponding same axis;
amplitude modulating each of the M linearly polarized optical beams;
driving M photodetectors with a corresponding one of the amplitude modulated M linearly polarized optical beams;
driving M antennas with a corresponding electrical output of a corresponding one of the M photodetectors.
18. The method of claim 17 , wherein the M linearly polarized optical beams are amplitude modulated linearly polarized optical beams.