DESC:DESCRIPTION
FIELD OF INVENTION
[0001] Embodiments of the present disclosure relate to communication system and more particularly relate to passive beam transfer array for wireless systems.
RELATED ART
[0002] In a wireless communication system a transmitter and a receiver (terms as is well understood in the field of art) exchange information/signal over wireless channel. The receiver (and/or the transmitter) is generally located such that it is (they are) in the line of sight (LOS) of the transmitter for better signal reception. However, any obstacle in the line of sight affects the signal quality received at the receiver. Such obstacles are more common in dense, urban areas due to high rise buildings, for example. In the urban conditions, receivers may establish wireless communication through non-line of sight path, generally due to reflection (unknown reflecting objects) of the transmitted signal from buildings. Such reception of reflected signal is undesirable. Several known remedies for such conditions includes increasing the transmit power and strategically positioning a passive reflector to provide a calculated non-line of sight path to the receiver.
[0003] FIG. 1A illustrates an example situation depicting the LOS and non LOS communication paths. As shown there the transmitter 110 is shown transmitting the signal. The receivers 120A and 120B are shown placed in the line of sight. The obstacle 130 is shown obstructing LOS of the receivers 120C and 120D. The receivers 120C and 120D are shown receiving the signal reflected from the unknown reflecting object 140. The signal received by the receivers 120C and 120D experience low signal to noise ratio (SNR).
[0004] In a certain prior technique, a known reflector 150 (as shown FIG. 1B) is positioned such that the receivers 120C and 120D may receive transmitted signal with higher signal to noise ratio. Conventionally, the reflector 150 is a reconfigurable intelligent surface (RIS) as is well known in the art. The RIS elements reflect the signal and allow fixed relationship between the angle of incidence and angle of reflection. That is, in order to change the angle of incidence or reflection (due to change in the receiver or transmitter position), the coefficients of each reflector element may be required to be changed. Further, RIS employs special material to cause reflection and may be challenging to set different reflecting angels with required precision. Thus, there is a need for a reflecting surface that is more efficient and provides a desired beam direction.
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SUMMARY
[0005]
According to an aspect, a communication system comprises a transmitter transmitting a communication signal in a first direction, a receiver receiving the communication signal in a second direction, and a passive beam transfer array (PBTA) configured to receive the communication signal in the first direction and retransmit the communication signal in the second direction. In that, the PBTA further comprises a first set of antennas configured to receive the communication in the first direction, a second set of antennas configured to transmit the communication in the second direction, and a first set of phase shifters coupled between the first set of antennas and the second set of antennas. According to another aspect the first set of phase shifters are configured with corresponding a set of phase shift values to form a receive beam and a transmit beam in the first and second direction respectively.
[0006]
According to another aspect, a device for changing the direction of a radio frequency signal comprises an array of antenna elements arranged over a surface wherein the surface is placed in the Line of sight of a transmitter transmitting a communication signal is configured to receive the communication signal in the first direction and retransmit the communication signal in the second direction.
[0007]
According to another aspect, the array of antenna elements on the surface is divided into sectors comprising a subset of antenna arrays, wherein each sector is configured to receive the communication signal in the first direction and retransmit the communication signal in a corresponding different direction.
BRIEF DESCRIPTION OF DRAWINGS
[0008]
FIG. 1A illustrates an example situation depicting the LOS and non-LOS communication paths.
[0009]
FIG. 1B illustrates prior reflecting surface 150.
[0010]
FIG. 2 is an example wireless communication system in an embodiment.
[0011]
FIG. 3 is an example PBTA in an embodiment.
[0012]
FIG. 4 illustrates the manner in which the direction (angle) of beam 350 and 360 may be set/ adjusted in an embodiment.
[0013]
FIG. 5 illustrates the manner in which the two set of phase shifters may be combined and the beam directions may be set with single set of phase shifters.
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[0014]
FIG. 6 illustrates an example device incorporating the phase shifters 530A-530K that may be programmed for desired beam direction.
[0015]
FIG. 7 illustrates the manner in which PBTA may be configured to reflect and/or receive the signal in multiple directions.
DETAILED DESCRIPTION OF THE PREFERRED EXAMPLES
[0016] FIG. 2 is an example wireless communication system in an embodiment. The wireless communication system 200 is shown comprising a transmitter 210, a passive beam transfer array (PBTA) 250 and receiver 290. In that, the transmitter 210 transmits a wireless signal on direction (path) 211. It is shown that an obstacle 201 is blocking the line of sight between the transmitter 210 and receiver 290. The PBTA 250 changes the direction or path of the wireless signal from path 211 to path 219 to reach/direct the transmitted signal to the receiver 290. The PBTA 250 provides for forming the receiving beam 220 and transmitting beam 230. The beam directions may be dynamically changed the based on the direction/path of the wireless signal 211 and the location of the receiver 290. PBTA 250 provides for changing the incidence angle 251 (angle the beam 220 makes with the plane of the PBTA) and/or reflecting angle 252 (angle the beam 230 makes with the plane of the PBTA) and/or relative angle between them. The PBTA 250 overcome at least some of the limitations of the RIS and other prior technique adopted to overcome non-line of sight wireless communication. The manner in which PBTA 250 may be implemented in an embodiment is further described below.
[0017] FIG. 3 is an example PBTA in an embodiment. The PBTA 300 is shown comprising N number of antenna elements 310A- 310N dispersed/arranged over an area A. In that, one part (or a set) of the antenna elements 310A-310K are configured to receive the transmitted signal on path 211 and the other elements 310L-310N are configured to transmit the signal on path 219. The Antenna elements 310A-310K are configured to form a beam 350 for receiving the signal on path 211. Similarly, the antenna elements 310L-310N are configured to form a beam 360 for transmitting in the direction 219. In other words, the direction of the beams 350 and 360 are respectively set in the direction of 211 and 219. The angle/direction of the beam 350/360 with respect (normal of) to the plane of the PBTA 300 may be dynamically adjusted based on the location of the transmitter 210 and receiver 290.
[0018] FIG. 4 illustrates the manner in which the direction (angle) of beam 350 and 360 may be set/adjusted in the PBTA in an embodiment. The PBTA 400 is shown antenna elements 410A-410K
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are shown coupled to a first set of phase shifters 420A-420K and the antenna elements 430L-430N are shown coupled to a second set of phase shifters 440L-440N. In that, the first set of phase shifters 420A-420K is shown adding a corresponding phase shift to the signal received on the antenna 410A-410K and combine (not explicitly shown, any combining technique like adder may be employed) the phase shifted signals to provide a received signal on path 424 that represent the transmitted signal from the transmitter 210 (say on path 211). The signal on path 424 is shown to split (splitter not shown) and provided to second set of phase shifter 440L-440N. The second set of phase shifters generate correspondingly phase shifted signals for transmission on the antenna elements 430L-430N. The beam 360 is formed in the direction based on the phase shifts caused by the second set of phase shifter 440L-440N. In other words, the phase shift value of each phase shifter 420A-420K and 440L-440n may be set to obtain the desired beam direction. In certain embodiment, the phase shifters angle may be determined in accordance with the uniform linear array antenna employed for of beam forming. Thus, direction of the beam 350 and 360 may be set to one of the directions 450A-450C and 460A-460C by selecting the phase value of phase shifter 420A-420K and 440L-440N.
[0019] FIG. 5 illustrates the manner in which the two set of phase shifters 410A-410K and 410A-410K may be combined in a PBTA and the beam directions may be set with single set of phase shifters. As shown there, the PBTA 500 comprises the antenna elements 510A-510K that are coupled to the antenna elements 520L-520K through a set of phase shifters 530A-530K. In this case, the number of antenna elements (510A-510K) that are configured for receiving the signal (say in the direction 211) are same as the number of the antenna elements (520LA-520K) configured to transmit (say in the direction 219). The phase angles of the phase shifters 530A-530K are selected based on the desired direction of beams 550 and 560. In an embodiment, the phase angles of each phase shifter 530A-530K are selected using a relation:
(1) ??(??)=S??(??2???? ????????(??-1) ??)[?????????? ?????????????????????? ??????????]????=1??(??2???? ????????(??-1) ??)????(??).
[0020] From the above relation, the effective complex weight for ith antenna pair may be determined from the relation:
(2) ????exp (Ø??)=??(??2???? ????????(??-1) ??)[?????????? ?????????????????????? ??????????]??(??2???? ????????(??-1) ??)
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[0021] In the above relation (1) and (2), the ???? represents the effective amplitude scaling, the Ø?? represents the effective phase shift to be set for the ith phase shifter in the 530A-530K phase shifters which couples ith antenna in the set of antenna elements 510A-510K to the ith antenna on the set of antenna elements 520A-520K, ?? representing the receive direction/ angle 550, ?? representing the transmission direction/angle 560, d representing the distance between the antenna elements, ?? representing the wavelength of the signal being redirected, N representing the total number of antenna pairs, ??(??) represeting the effective transmitted signal in the air after receive and transmit beamforming and ????(??) representing the received signal from the ith receive antenna.
[0022] For example, when the angle 550 is desired to be 60 degrees (??3radians) and the angle 560 is desired to be 120 degrees (2??3radians), then the effective complex weight applied to the first phase shifter 530A may be determined as:
Ø530??=??(??2???? ????????3(1-1) ??)[?????????? ??????2??3?????????????? ??????2??3??]??(??2???? ??????2??3(??-1) ??). Similarly, the complex weights of the other phase shifter may be determined.
[0023] FIG. 6 illustrates an example device incorporating the phase shifters 530A-530K that may be programmed for desired beam direction. The device 600 is shown comprising phase shifters 610_610K (operative similar to 530A-530K). The direction to phase converter 620, and memory 630. The device 600 is shown receiving the signal from the antenna (for example, receiving antennas 510A-510K), the received K number of signals are coupled to corresponding inputs of the phase shifters 610A-610K, the output of the phase shifters 610A-610K are coupled to the transmitting antenna 520A-520K. The direction to phase converter (DPC) 620 is shown receiving the desired direction (angle) on path 621 and an offset value (distance between the antenna d) on path 622. The DPC 620 determine the phase angles to be set for phase shifters 610A-610K for effectively obtain the direction of beams 550 and 560 according the received direction on path 621. The angle received on path 621 may comprise both receiving beam angle and transmitted beam angle or relative angle between them. The DPC 620 may determine the phase shift angle for each phase shifter using the relation (2). The DPC 620 may set the phase of each phase shifter as per the determined values for given directions of the beams. The wavelength of the signal may be determined on the device. Further, in certain embodiment, the DPC 620 may store the computed phase angels for particular direction of beams in the memory 630. The stored predetermined values
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of phase angles may be retrieved for setting the phase value of the phase shifter without having to compute again. Thus, PBTA 600 becomes easily programmable for any desired direction (for transmitting and receiving direction pairs) to redirect the signal received on path 211.
[0024] FIG. 7 illustrates the manner in which PBTA may be configured to reflect and/or receive the signal in multiple directions. The PBTA 700 is shown divided into four quarters (for example), each quarter 710-740 may operate independently. For example, the N numbers of antenna in the area A of PBTA may be divided into N/4 antenna elements per quarter. That means each quarter 710-740 may comprise N/4 antenna elements. The N/4 antenna elements in each quarter are divided into a set of transmitting antennas (marked with dark shades in the quarter) and a set of receiving antennas (marked with no shades). The various quarter pairs can be configured to steer the beams in azimuth direction or elevation direction or the combination of azimuth and elevation directions. Thus, each quarter may comprise N/8 transmitting antenna and N/8 receiving antenna. Accordingly, N/8 number of phase shifters is employed/implemented in each quarter 710-740. Thus, total number of phase shifters remains same in the PBTA 700 compared to when implemented without dividing into the number of quarters. The Each quarter may be configured for same receiving beam direction with different transmit beam directions, for example. As a result, the signal transmitted by the transmitter 210 in the direction 211 is received by the PBTA 700 effectively and the PBTA 700 transmits (reflects) the signal in multiple (four in this cases) directions (to reach corresponding receivers that are at different location). Similarly, any other directional choices of transmit beam and receive beam may be implemented. Alternatively, when all quarters 710-740 are configured for same transmit beam direction and receive beam directions, the PBTA 700 may operate similar to the PBTA 300/400/500/600. Dividing in quarter may provide simplicity of implementation and/or additional flexibility in selecting multiple transmits and receives directions.
[0025] While various embodiments of the present disclosure have been described above, it should be understood that they have been presented by way of example only, and not limitation. Thus, the breadth and scope of the present disclosure should not be limited by any of the above-discussed embodiments but should be defined only in accordance with the following claims and their equivalents. ,CLAIMS:I/We claim,
1.
A communication system comprising:
a transmitter transmitting a communication signal in a first direction;
a receiver receiving the communication signal in a second direction; and
a passive beam transfer array (PBTA) configured to receive the communication signal in the first direction and retransmit the communication signal in the second direction.
2.
The communication system of claim 1, wherein the PBTA further comprising:
a first set of antennas configured to receive the communication in the first direction;
a second set of antennas configured to transmit the communication in the second direction;
a first set of phase shifters coupled between the first set of antennas and the second set of antennas.
3.
The communication system of claim 2, wherein the first set of phase shifters are configured with corresponding a set of phase shift values to form a receive beam and a transmit beam in the first and second direction respectively.
4.
The communication system of claim 3, where in the set of phase angles are determined from relation:
????exp (Ø??)=??(??2???? ????????(??-1) ??)[?????????? ?????????????????????? ??????????]??(??2???? ????????(??-1) ??)
wherein, ???? represents the effective amplitude scaling, Ø?? represents the set of phase shifts with i taking value from 1 to N, ?? representing the first direction, ?? representing the second direction, d representing the distance between the antennas in the first and second set of antennas, ?? representing the wavelength of the communication signal, N representing the total number of phase shifters in the set of phase shifters.
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5.
A device for changing the direction of a radio frequency signal comprising:
an array of antenna elements arranged over a surface wherein the surface is placed in the Line of sight of a transmitter transmitting a communication signal is configured to receive the communication signal in the first direction and retransmit the communication signal in the second direction.
6.
The device of claim 5, comprising:
a first set of antennas in the array configured to receive the communication in the first direction;
a second set of antennas in the array configured to transmit the communication in the second direction;
a first set of phase shifters coupled between the first set of antennas and the second set of antennas.
7.
The device of claim 6, wherein the first set of phase shifters are configured with corresponding a set of phase shift values to form a receive beam and a transmit beam in the first and second direction respectively.
8.
The device of claim 7, where in the set of phase angles are determined from relation:
????exp (Ø??)=??(??2???? ????????(??-1) ??)[?????????? ?????????????????????? ??????????]??(??2???? ????????(??-1) ??)
wherein, ???? represents the effective amplitude scaling, Ø?? represents the set of phase shifts with i taking value from 1 to N, ?? representing the first direction, ?? representing the second direction, d representing the distance between the antennas in the first and second set of antennas, ?? representing the wavelength of the communication signal, N representing the total number of phase shifters in the set of phase shifters.
9.
The device of claim 5, wherein the array of antenna elements on the surface is divided into sectors comprising a subset of antenna arrays, wherein each sector is configured to
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receive the communication signal in
the first direction and retransmit the communication signal in a corresponding different direction.
10.
A method, system, and apparatus for radar receiver system comprising one or more features described in the specifications and drawings