# US 10,375,662 B2 · Method and apparatus of implementing time synchronization

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- Number: US 10,375,662 B2
- Document ID: US10375662B2
- Status: Granted
- Kind: B2
- Application number: 15/619,806
- Filed: 2017-06-12
- Published: 2017-09-28
- Granted: 2019-08-06
- Earliest claimed: 2011-01-26
- Assignees: Huawei Technologies Co., Ltd.
- Applicants: Huawei Technologies Co., Ltd.
- Inventors: Liexun Feng; Yong He
- Web page: https://patentgrep.com/patent/US10375662B2

## CPC

- H04W 56/0015: {one node acting as a reference for the others}
- H04B 10/25: Arrangements specific to fibre transmission
- H04B 10/25753: {Distribution optical network, e.g. between a base station and a plurality of remote units}
- H04J 3/0638: {Clock or time synchronisation among nodes; Internode synchronisation (synchronization for ring networks H04L12/422; data switching networks with synchronous transmission H04L12/43)}
- H04J 14/0204: {Broadcast and select arrangements, e.g. with an optical splitter at the input before adding or dropping}
- H04J 3/0667: {Bidirectional timestamps, e.g. NTP or PTP for compensation of clock drift and for compensation of propagation delays (arrangements for monitoring round trip delays in packet switching networks H04L43/0864)}
- H04W 88/085: {Access point devices with remote components}
- H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72)
- H04B: TRANSMISSION
- H04J: MULTIPLEX COMMUNICATION (transmission in general H04B; peculiar to transmission of digital information H04L5/00; systems for the simultaneous or sequential transmission of more than one television signal H04N7/08; in exchanges H04Q11/00; stereophonic systems H04S)

## Abstract

A method of time synchronization and a base station system are disclosed. The base station system includes a main unit, at least one radio unit, and a transmission medium adapted to transmit information between the main unit and the at least one radio unit. The base station system further includes a clock synchronization server configured close to the side of the at least one radio unit or integrated with the at least one radio unit. The clock synchronization server is adapted to transmit synchronization data to the main unit through the transmission medium, so that the main unit performs configuration processing according to the synchronization data to implement time synchronization with the clock synchronization server.

## Claims

### Claim 1

A base station, comprising:
a plurality of remote radio units (RRUs) to transmit service data;
a clock synchronization server to transmit first synchronization data;
a first optical adapter including a first optical fiber interface and in communication with the plurality of RRUs and the clock synchronization server, the first optical adapter configured to converge the synchronization data from the clock synchronization server and service data from the plurality of RRUs;
a main system configured to receive the first synchronization data from a clock synchronization server and perform configuration processing according to the first synchronization data to implement time synchronization with the clock synchronization server, the main system including:
a second optical adapter configured to split the converged synchronization data and the service data,
a plurality of baseband control units (BBUs), and
one or more transfer switches
configured to cause transmitting synchronization data from the clock synchronization server to the plurality of BBUs.

### Claim 2 (depends on 1)

The base station according to claim 1,
wherein the at least one optical fiber is configured to be connected to cause transmitting information between the main system and the plurality of RRUs and synchronization data from the clock synchronization server to the main system.

### Claim 3 (depends on 2)

The base station according to claim 2, wherein the plurality of BBUs are installed in a machine room in a centralized manner.

### Claim 4 (depends on 3)

The base station according to claim 3, wherein the plurality of RRU are installed outdoors close to at least one antenna.

### Claim 5 (depends on 1)

The base station according to claim 1, wherein
each of the plurality of BBUs comprises a baseband radio frequency interface and a synchronization interface coupled to the second optical adapter,
the baseband radio frequency interface is configured to transmit and receive service data, and
the synchronization interface is configured to transmit synchronization data.

### Claim 6 (depends on 5)

The base station according to claim 5, wherein the first optical adapter and the second optical adapter are optical add-drop multiplexers (OADMs).