Method for fast beam sweeping and device discovery in 5G millimeter wave and upper centimeter-wave systems

Patent metadata

Field	Value
Publication number	US-10972172-B2
Application number	US-201916593867-A
Country	US
Kind code	B2
Filing date	Oct 4, 2019
Priority date	Oct 5, 2018
Publication date	Apr 6, 2021
Grant date	Apr 6, 2021

Abstract

A method of performing a beam alignment procedure in a mmW or upper centimeter wave system, usable for performing initial access (IA) for user equipment (UE) to establish a connection with a base station (BS) is disclosed. A UE receives a signal from a base station, divides a search space into a plurality of angular zones, locates a direction of peak received strength within each zone, and forms a beam along the direction of peak overall signal strength. The number of angular zones is chosen such that the probability that each zone contains one peak of signal strength exceeds some threshold. The method is applicable in mmW and upper cmW bands in both BS to UE and device-to-device (D2D) communications.

First claim

What is claimed is:

1. A method of aligning an antenna beam to a source of signals, comprising:
dividing an angular search space into a plurality of angular search zones;
measuring received signal strength within each angular search zone and, on the basis of the measurement, determining a direction of maximum received signal strength for each search zone; and
comparing the maximum signal strengths for each of the search zones, and aligning the antenna beam along the direction of overall maximum signal strength.

2. The method of claim 1 , wherein the step of dividing the angular search space into a plurality of search zones comprises:
selecting a total number of angular search zones such that the probability that each angular search zone contains a single peak in a function of signal strength versus angle of arrival at the antenna exceeds a predetermined threshold.

3. The method of claim 1 , wherein the step of determining a direction of maximum received signal strength for each search zone comprises, within each search zone, taking received signal strength samples using a plurality of probe beams oriented in different directions according to a binary search algorithm.

4. The method of claim 1 , wherein the step of determining a direction of maximum received signal strength for each search zone includes the steps of:
(1) defining a baseline receive beam oriented at the center of the search zone and sampling a baseline received signal strength along the baseline receive beam;
(2) defining a plurality of probe receive beams at angles surrounding baseline receive beam and sampling received signal strength along the probe receive beams, and on that basis, determining a direction in which received signal strength is rising relative to the baseline beam;
(3) defining a new baseline receive beam in the angular direction of the probe beam that was defined in the direction of rising signal strength and sampling a new baseline received signal strength along the baseline receive beam;
(4) defining a new plurality of probe receive beams at angles surrounding the new baseline receive beam and sampling received signal strength along the new probe receive beams, and on that basis, determining a direction in which received signal strength is rising relative to the new baseline beam;
repeating steps 3-4 until a final probe receive beam is defined that exhibits a signal strength within a predefined range relative to a baseline beam, and
defining the final probe beam as the direction of maximum signal strength for the zone.

5. The method of claim 1 , wherein the antenna beam is generated by a directional antenna on a cellular user equipment and the source of signals is a cellular base station.

6. The method of claim 1 , wherein the antenna beam is generated by an antenna at a first transceiver, and the source of signals is a second transceiver.

7. The method of claim 6 , wherein the first transceiver and the second transceiver are cellular user equipment.

8. The method of claim 6 , wherein the first and second transceivers are operating in the 5G frequency domain.

9. The method of claim 1 , wherein the source of signals is transmitting in the frequency band between 20 to 30 GHz.

10. The method of claim 1 , wherein the antenna beam is formed by a uniform planar phased array antenna.

11. The method of claim 1 , wherein the antenna is in electrical communication with a cellular user equipment and the source of signals is a cellular base station, and wherein antenna beams are formed by the user equipment by selecting among a set of predefined beams stored in a user equipment codebook.

12. A method of forming a beam between a cellular base station (“BS”) having a directional antenna with a cellular user equipment (“UE”) having a directional antenna, compromising:
receiving a first directional signal from the base station, the received signal containing a BS beam id;
forming a directional receive beam at UE by:
dividing an angular search space into angular zones, such that the probability that each angular search zone contains a single peak in a function of received signal strength versus angle of arrival at the UE antenna exceeds a predetermined threshold;

locating a receive beam within each angular search zone in the direction of peak received signal strength, and
comparing the beams with the highest received signal strength within each zone across zones to determine a receive beam having the highest overall received signal strength, and
forming a beam along the direction of having highest overall received signal strength.

13. The method of claim 12 , wherein the step of locating a receive beam within each angular search zone in the direction of peak received signal strength comprises iteratively forming directional receive beams within each angular zone, measuring received signal strength with these beams, and determining the beam with the highest received signal strength within each zone.

14. The method of claim 13 , wherein the step of iteratively forming directional receive beams within each angular zone comprises implementing a binary search algorithm to locate the direction of peak received signal strength within the zone.

15. The method of claim 14 , wherein the step of implementing a binary search algorithm to locate the direction of peak received signal strength within the zone comprises:
(1) defining a baseline receive beam oriented at a center of the zone and sampling a baseline received signal strength along the baseline receive beam;
(2) defining a plurality of probe receive beams at angles surrounding the baseline receive beam and sampling received signal strength along the probe receive beams, and on that basis, determining a direction in which received signal strength is rising relative to the baseline beam;
(3) defining a new baseline receive beam along the direction of the probe beam that was defined in the direction of rising signal strength and sampling a new baseline received signal strength along the baseline receive beam;
(4) defining a new plurality of probe receive beams at angles surrounding the new baseline receive beam and sampling received signal strength along the probe receive beams, and on that basis, determining a direction in which received signal strength is rising relative to the new baseline beam, where the new plurality of probe beams have less angular deviation from the new baseline beam as the previous set of probe beams;
repeating steps 3-4 until a final probe beam is defined that exhibits no rising signal strength relative to a baseline beam.

16. The method of claim 12 , further comprising storing a data record comprising a BS beam id, a selected best UE beam corresponding to the BS beam id, and a measure of signal quality on a link employing the BS beam and the selected best UE beam.

17. The method of claim 16 , further comprising receiving additional directional signals from the base station, the additional received signals containing additional BS beam ids, forming corresponding receive beams at the UE, the receive beams being associated with the highest obtainable received signal strength, and storing data records comprising the BS beam ids, selected best UE beams corresponding to the BS beam ids, and a measure of signal quality on a link employing each BS beam and the corresponding best UE beam.

18. The method of claim 17 , comprising reviewing the stored data records and, on the basis of the review, selecting from among pairs of BS beams and UE beams the beam pair associated with the highest overall signal strength

Assignees

• Univ Arizona

Inventors

• Krunz Marwan
• Aykin Irmak
• Akgun Berk

Classifications

• H04W72/23

  in the downlink direction of a wireless link, i.e. towards a terminal · CPC title

• H04B7/06952 Primary

  Selecting one or more beams from a plurality of beams, e.g. beam training, management or sweeping · CPC title

• H04B7/086 Primary

  using weights depending on external parameters, e.g. direction of arrival [DOA], predetermined weights or beamforming · CPC title

• H04B7/088

  using beam selection · CPC title

• H04B7/024

  Co-operative use of antennas of several sites, e.g. in co-ordinated multipoint or co-operative multiple-input multiple-output [MIMO] systems · CPC title