Deterministic low-complexity beam alignment for 5G and 6G users
View Patent ↗5G and especially 6G are built around beamed transmissions and receptions, but aligning the beams toward the intended recipient is currently an expensive and complex process that reduced-capability devices may have difficulty performing. Therefore, an improved beam alignment process is disclosed, involving “triangle” beams. A triangle beam is a wide transmission beam that is arranged to be high-power at one side and low-power at the other side, tapering monotonically between the two angles. A user device can detect the triangle beam and measure the received amplitude or power level. By comparing to the amplitude of a previous transmission, the user device can determine its angle relative to the base station. The user device can then transmit directional beams toward the base station, and can also inform the base station of the angle so that they both can use well-directed transmission and reception beams. Many other aspects are disclosed.
1. A method for a base station of a wireless network to communicate with a user device of the wireless network, the method comprising:
a) isotropically transmitting a first signal comprising a maximum power level; and
b) transmitting a second signal according to a triangle beam distribution, wherein the triangle beam distribution comprises the maximum power level in a first angular direction and a minimum power level in a second angular direction, and wherein a power level of the triangle beam distribution varies monotonically with angle between the first and second angular directions.
2. The method of claim 1 , wherein the first signal is transmitted according to at least 5G technology.
3. The method of claim 1 , wherein the minimum power level comprises a predetermined fraction of the maximum power level.
4. The method of claim 3 , wherein the predetermined fraction equals one-tenth.
5. The method of claim 1 , wherein the triangle beam distribution spans 360 degrees.
6. The method of claim 1 , further comprising receiving, from the user device, a message indicating a first received amplitude or power measured during the first signal and a second received amplitude or power measured during the second signal.
7. The method of claim 6 , further comprising:
a) calculating, according to the first and second received amplitudes or powers, a first angular direction toward the base station from the user device;
b) calculating, according to the angular direction toward the base station from the user device, a second angular direction toward the user device from the base station; and
c) transmitting, on a beam aimed according to the second angular direction, a reply message indicating the first angular direction.
8. The method of claim 1 , wherein the first signal comprises a demodulation reference.
9. The method of claim 1 , wherein the first signal comprises a system information message transmitted on a PBCH (physical broadcast channel) or a PDSCH (physical downlink shared channel) of the base station.
10. The method of claim 1 , wherein the first signal comprises a downlink message associated with initial access, the downlink message comprising a Msg2 message or a Msg4 message of a four-step access procedure, or a MsgB message of a two-step access procedure.
11. The method of claim 1 , further comprising transmitting a third signal according to a reversed triangle beam distribution, wherein the reversed triangle beam distribution comprises the minimum power level in the first angular direction and the maximum power level in the second angular direction, and wherein the power level of the reversed triangle beam distribution varies monotonically with angle between the first and second angular directions.