Over-the-air synchronization of radio nodes in a radio access network

Patent metadata

Field	Value
Publication number	US-11832199-B2
Application number	US-202318096263-A
Country	US
Kind code	B2
Filing date	Jan 12, 2023
Priority date	Jan 30, 2019
Publication date	Nov 28, 2023
Grant date	Nov 28, 2023

Abstract

A method is provided for synchronizing timing in phase and frequency of clocks associated with a plurality of radio nodes (RNs) in a small cell radio access network (RAN) having an access controller operatively coupled to each of the RNs. In accordance with the method, a donor list is generated for each given RN in the RAN. The donor list represents an ordered list of potential wireless access points that are able to serve as a source of a wireless sync signal for the given RN. The donor lists are distributed to the respective RNs. An access point is selected by each of the RNs from their respective donor lists to use as a sync signal source. Each of the RNs synchronize their respective clocks in phase and frequency using wireless sync signals received from the respective selected access points.

First claim

The invention claimed is:

1. A wireless communication system, comprising:
a plurality of radio nodes (RNs) each configured to serve a respective one of a plurality of radio coverage areas; and
an access controller coupled to the plurality of RNs and configured to:
generate a donor list representing an ordered list of wireless access points among the plurality of RNs that can serve as a source of a wireless sync signal for any selected RN among the plurality of RNs; and
distribute the donor list to the selected RN.

2. The wireless communication system of claim 1 , wherein the selected RN is configured to:
determine a selected wireless access point from the ordered list of wireless access points to use as the source of the wireless sync signal;
synchronize a respective clock in phase and frequency based on the wireless sync signal received from the selected wireless access point; and
provide information concerning a current sync status to the access controller.

3. The wireless communication system of claim 2 , wherein the selected RN is further configured to provide the information concerning the current sync status to the access controller periodically.

4. The wireless communication system of claim 2 , wherein the selected RN is further configured to determine a different wireless access point from the ordered list of wireless access points to use as the source of the wireless sync signal when synchronization to the selected wireless access point is lost.

5. The wireless communication system of claim 1 , wherein the access controller is further configured to assign a respective score to each wireless access point in the ordered list of wireless access points to indicate a respective quality rank when used as the source of the wireless sync signal.

6. The wireless communication system of claim 1 , wherein the access controller is further configured to generate the donor list by generating a directed graph having a plurality of nodes each corresponding to a respective one of the plurality of RNs.

7. The wireless communication system of claim 6 , wherein the access controller is further configured to expand the directed graph to obtain a sync tree using data obtained from a radio environment monitoring (REM) scan.

8. The wireless communication system of claim 7 , wherein the access controller is further configured to expand the directed graph using a minimum spanning tree algorithm to thereby minimize a depth of the sync tree from a root node serving as a master synchronization source to any child node, the depth of the sync tree being measured in units of hops from the root node to any given child node.

9. The wireless communication system of claim 7 , wherein the access controller is further configured to:
coordinate a boot order among the plurality of RNs based on the sync tree;
instruct a respective one of the plurality of RNs to boot up first when the respective one of the plurality of RNs is closest to a root node of the sync tree in units of hops; and
instruct the respective one of the plurality of RNs to boot up last when the respective one of the plurality of RNs is farthest from the root node of the sync tree in the units of hops.

10. The wireless communication system of claim 7 , wherein the access controller is further configured to coordinate a muting pattern to thereby prevent a respective one of the plurality of RNs from transmitting under any one or more of the following conditions:
the respective one of the plurality of RNs is attempting to obtain the wireless sync signal; and
any other one of the plurality of RNs closer to a root node in the sync tree than the respective one of the plurality of RNs is listening for the wireless sync signal.

Assignees

• Corning Optical Communications LLC

Inventors

• Chen Tsung-Yi
• Duval Olivier
• Nama Hithesh

Classifications

• H04W56/001 Primary

  Synchronization between nodes · CPC title