Resource-Efficient Low-Complexity Beamforming Feedback in 5G/6G

Abstract

In a 5G or 6G wireless network, the base station can assist user devices in aligning their beams toward the base station, and can align downlink beams toward each of the user devices, by exchanging brief test signals followed by brief encoded feedback messages. The test signals may be transmitted in different directions, or with different beam widths, or with other transmission parameters, thereby enabling the user device to select the best version and reply accordingly. In addition, the user device can determine, from information in a message accompanying the test signals, a direction or angle of each test signal, and thereby determine the correct direction toward the base station by adding 180 degrees, without further experimentation. For compact messaging, a zero-power state may be included in the modulation scheme, thereby providing an efficient format for selecting which beam or which direction is best received.

1 . A method for a base station of a wireless network, the method comprising:
 a) receiving, from a user device of the wireless network, a request to adjust a downlink transmission beam;   b) transmitting, to the user device, integer Nsig test signals, wherein each test signal is transmitted using a different value of a transmission parameter;   c) receiving, from the user device, a feedback message indicating a particular test signal of the Nsig test signals;   d) adjusting the transmission parameter to a particular value according to the particular test signal; and   e) transmitting, using the transmission parameter adjusted to the particular value, an acknowledgement to the user device.   
     
     
         2 . The method of  claim 1 , wherein the Nsig test signals are transmitted according to 5G or 6G technology. 
     
     
         3 . The method of  claim 1 , wherein:
 a) the Nsig test signals are transmitted concatenated with a downlink message; and   b) the downlink message comprises an indication that the downlink message includes the Nsig test signals.   
     
     
         4 . The method of  claim 3 , wherein the downlink message further comprises an indication whether subsequent messages to the user device are to include further test signals. 
     
     
         5 . The method of  claim 3 , wherein:
 a) a first test signal, of the Nsig test signals, precedes the downlink message, and a second test signal, of the Nsig test signals, follows the downlink message;   b) and wherein the method further comprises:
 i) measuring a first phase of the first test signal and a second phase of the second test signal; and 
 ii) before demodulating the downlink message, correcting a phase of the downlink message according to the first and second phases. 
   
     
     
         6 . The method of  claim 1 , wherein the transmission parameter comprises an angular width of the downlink transmission beam. 
     
     
         7 . The method of  claim 1 , further comprising:
 a) receiving, concatenated with the feedback message, Nsig uplink test signals; and   b) transmitting, concatenated with or multiplexed with the acknowledgement, an indication which of the Nsig uplink test signals was received by the base station with a highest signal quality.   
     
     
         8 . The method of  claim 1 , further comprising:
 a) receiving, concatenated with the feedback message, Nsig uplink test signals; and   b) transmitting, concatenated with or multiplexed with the acknowledgement, an indication which two uplink test signals, of the Nsig uplink test signals, were received by the base station with equal or nearly equal signal quality.   
     
     
         9 . The method of  claim 1 , wherein:
 a) Nsig equals three;   b) the three test signals comprise a “higher” test signal, a “middle” test signal, and a “lower” test signal, wherein the transmission parameter of the middle test signal is higher than the transmission parameter of the lower test signal and lower than the transmission parameter of the higher test signal; and   c) the acknowledgement is concatenated with an “upper” test signal and a “downer” test signal, wherein the transmission parameter of the acknowledgement message is higher than the transmission parameter of the downer test signal and lower than the transmission parameter of the upper test signal.   
     
     
         10 . The method of  claim 9 , further comprising:
 a) determining a first separation comprising a difference between the transmission parameter of the higher test signal and the transmission parameter of the lower test signal, as received by the base station;   b) configuring a second separation comprising a difference between the transmission parameter of the upper test signal and the transmission parameter of the downer test signal, as transmitted by the base station;   c) when the feedback message indicates the middle test signal, configuring the second separation to be less than the first separation; and   d) when the feedback message indicates either the higher or lower test signal, configuring the second separation to be larger than the first separation.   
     
     
         11 . Non-transitory computer-readable media in a user device of a wireless network, the non-transitory computer-readable media containing instructions that, when executed by a computing environment, cause a method to be performed, the method comprising:
 a) transmitting, to a base station of the wireless network, a request to adjust a downlink transmission beam;   b) receiving a downlink message from a base station of the wireless network, the downlink message concatenated with integer Nsig test signals, each test signal transmitted in a different direction;   c) determining a particular test signal, of the Nsig test signals, having a highest signal quality as received by the user device; and   d) transmitting a feedback message to the base station, the feedback message comprising a single resource element indicating the particular test signal, and further indicating a request for a transmission power adjustment;   e) wherein the feedback message is modulated according to a particular modulation scheme comprising integer Nstate modulation states, wherein Nstate equals 3 times Nsig.   
     
     
         12 . The non-transitory computer-readable media of  claim 11 , wherein:
 a) Nsig equals three;   b) the particular modulation scheme comprises nine modulation states; and   c) each modulation state comprises an amplitude-modulated I branch, multiplexed with an orthogonal amplitude-modulated Q branch.   
     
     
         13 . The non-transitory computer-readable media of  claim 11 , wherein:
 a) Nsig equals three;   b) the particular modulation scheme comprises nine modulation states; and   c) each modulation state comprises amplitude modulation according to three predetermined amplitude levels, multiplexed with phase modulation according to three predetermined phase levels.   
     
     
         14 . The non-transitory computer-readable media of  claim 11 , the method further comprising:
 a) determining, from the downlink message, Nsig transmission directions associated with the Nsig test signals, respectively; and   b) calculating a direction toward the base station by adding 180 degrees to a particular transmission direction associated with the particular test signal.   
     
     
         15 . The non-transitory computer-readable media of  claim 14 , wherein the feedback message is transmitted in the direction toward the base station. 
     
     
         16 . The non-transitory computer-readable media of  claim 14 , wherein the feedback message, or a second message concatenated with the feedback message, indicates the direction toward the base station. 
     
     
         17 . A method for a first mobile user device of a sidelink network, the method comprising:
 a) broadcasting a broadcast message indicating whether the first mobile user device is able to demodulate messages modulated according to a modulation scheme that includes a zero-power modulation state, wherein the zero-power modulation state comprises a modulation state comprising zero transmission;   b) receiving, from a second mobile user device, an indication whether the second user device is able to demodulate messages modulated according to the modulation scheme that includes the zero-power modulation state;   c) when the second mobile user device is able to demodulate messages modulated according to the modulation scheme that includes the zero-power modulation state, transmitting, to the second user device, a further message modulated according to the modulation scheme that includes the zero-power modulation state, wherein the further message comprises a first selection multiplexed with a second selection, the first selection indicating a first transmission parameter and the second selection indicating a second transmission parameter; and   d) when the first mobile user device is able to demodulate messages modulated according to the modulation scheme that includes the zero-power modulation state, receiving, from the second mobile user device, a reply message modulated according to the modulation scheme that includes the zero-power modulation state.   
     
     
         18 . The method of  claim 17 , wherein the modulation scheme that includes the zero-power modulation state comprises 9QAM (quadrature amplitude modulation with nine modulation states) comprising an I-branch signal amplitude-modulated according to three amplitude levels, multiplexed with an orthogonal Q-branch signal amplitude-modulated according to the three amplitude levels, wherein the three amplitude levels comprise +1, zero, and −1 arbitrary units of amplitude. 
     
     
         19 . The method of  claim 17 , wherein the modulation scheme that includes the zero-power modulation state comprises amplitude modulation and phase modulation comprising ten modulation states, wherein:
 a) nine of the modulation states comprise amplitude modulation according to three non-zero amplitude levels, multiplexed with phase modulation according to the three phase levels; and   b) a tenth modulation state, of the modulation states, comprises zero transmission.   
     
     
         20 . The method of  claim 17 , wherein the zero-power modulation state represents a gap between a message and a demodulation reference.