Method and device for synchronization between base stations

1. A method for synchronization between base stations, comprising:

receiving, by a slave base station, a cell reference signal (CRS) sent by a first master base station, on a specific symbol in a special subframe via a primary radio frequency integrated circuit (RFIC); and

performing, by the slave base station, synchronization between the slave base station and the first master base station according to the received CRS;

wherein before said receiving, by the slave base station, the CRS sent by the first master base station, on the specific symbol in the special subframe via the primary RFIC, the method further comprises:

switching, by the slave base station, from a transmitting state to a receiving state within a first duration before a start point of the specific symbol; and

after said performing, by the slave base station, synchronization between the slave base station and the first master base station according to the received CRS, the method further comprises:

switching, by the slave base station, from the receiving state to the transmitting state within a second duration after an end point of the specific symbol;

wherein the first duration and the second duration are smaller than a duration occupied by a cyclic prefix (CP) used when the slave base station transmits a downlink data signal on each symbol.

2. The method according to claim 1 , wherein before said receiving, by the slave base station, the CRS sent by the first master base station, on the specific symbol in the special subframe via the primary RFIC, the method further comprises:

acquiring, by the slave base station after startup, neighboring cell information of neighboring base stations by scanning the neighboring base stations within a frequency band supported by the slave base station; wherein the neighboring cell information comprises at least signal transmitting powers of the neighboring base stations; and

selecting, by the slave base station, a neighboring base station from the neighboring base stations as the first master base station; wherein the selected neighboring base station has a highest signal transmitting power among the acquired signal transmitting powers of the neighboring base stations and the highest signal transmitting power satisfies a preset power threshold.

3. The method according to claim 1 , wherein before said receiving, by the slave base station, the CRS sent by the first master base station, on the specific symbol in the special subframe via the primary RFIC, the method further comprises:

determining, by the slave base station, that a preset synchronization tracking period has been reached.

4. The method according to claim 1 , wherein the specific symbol is a symbol 4 or a symbol 7 in the special subframe.

5. The method according to claim 1 , further comprising:

not scheduling, by the slave base station, physical downlink shared channel (PDSCH) data during the synchronization.

6. The method according to claim 1 , further comprising:

calculating, by the slave base station, a reference signal received power (RSRP) of the CRS;

determining, by the slave base station, that the synchronization has failed when the calculated RSRP is smaller than a preset synchronization detection protection threshold, and RSRPs of the first master base station calculated in the slave base station during the last consecutive N times of synchronization are smaller than the preset synchronization detection protection threshold, wherein N is a preset integer greater than 1; and

reselecting, by the slave base station, a second master base station in response to that the synchronization has failed.

7. A slave base station, comprising at least a baseband processing element and a primary radio frequency integrated circuit (RFIC), wherein:

the baseband processing element is configured to receive a cell reference signal (CRS) sent by a first master base station on a specific symbol of a special subframe via the primary RFIC; and perform synchronization between the slave base station and the first master base station according to the received CRS; and

the primary RFIC is configured to listen to the CRS sent by the first master base station;

wherein before receiving the CRS sent by the first master base station, on the specific symbol in the special subframe via the primary RFIC, the baseband processing element is further configured to:

switch from a transmitting state of the primary RFIC to a receiving state within a first duration before a start point of the specific symbol;

after performing synchronization between the slave base station and the first master base station according to the received CRS, the baseband processing element is further configured to:

switch from the receiving state of the primary RFIC to the transmitting state within a second duration after an end point of the specific symbol;

wherein the first duration and the second duration adopted by the baseband processing element are smaller than a duration occupied by a cyclic prefix (CP) used when the primary RFIC transmits a downlink data signal on each symbol.

8. The slave base station according to claim 7 , further comprising:

a baseband element configured to, after startup, acquire neighboring cell information of neighboring base stations by scanning the neighboring base stations within a frequency band supported by the slave base station, before the baseband processing element receives the CRS sent by the first master base station on the specific symbol in the special subframe via the primary RFIC; wherein the neighboring cell information comprises at least signal transmitting powers of the neighboring base stations;

wherein the baseband processing element is further configured to:

select a neighboring base station from the neighboring base stations as the first master base station, wherein the selected neighboring base station has a highest signal transmitting power among the acquired signal transmitting powers of the neighboring base stations and the highest signal transmitting power satisfies a preset power threshold.

9. The slave base station according to claim 7 , wherein before receiving the CRS sent by the first master base station on the specific symbol in the special subframe via the primary RFIC, the baseband processing element is further configured to:

determine that a preset synchronization tracking period has been reached.

10. The slave base station according to claim 7 , wherein the specific symbol adopted by the baseband processing element is a symbol 4 or a symbol 7 in the special subframe.

11. The slave base station according to claim 7 , wherein the baseband element is further configured:

not to schedule physical downlink shared channel (PDSCH) data during the synchronization.

12. The slave base station according to claim 7 , wherein the baseband processing element is further configured to:

calculate a reference signal received power (RSRP) of the CRS;

determine that the synchronization has failed when the calculated RSRP is smaller than a preset synchronization detection protection threshold, and RSRPs of the first master base station calculated in the slave base station during the last consecutive N times of synchronization are smaller than the preset synchronization detection protection threshold, wherein N is a preset integer greater than 1; and

reselect a second master base station in response to that the synchronization has failed.

13. A method for synchronization between base stations, comprising:

receiving, by a slave base station, a cell reference signal (CRS) sent by a first master base station, on a specific symbol in a special subframe via a primary radio frequency integrated circuit (RFIC); and

performing, by the slave base station, synchronization between the slave base station and the first master base station according to the received CRS;

wherein before said receiving, by the slave base station, the CRS sent by the first master base station, on the specific symbol in the special subframe via the primary RFIC, the method further comprises:

switching, by the slave base station, from a transmitting state to a receiving state within a first duration before a start point of the specific symbol; and

after said performing, by the slave base station, synchronization between the slave base station and the first master base station according to the received CRS, the method further comprises:

switching, by the slave base station, from the receiving state to the transmitting state within a second duration after an end point of the specific symbol;

wherein said performing, by the slave base station, synchronization between the slave base station and the first master base station according to the received CRS comprises:

synchronously adjusting, by the slave base station, a time domain position of a frame header locally maintained by the slave base station based on time synchronization information carried by the CRS; and

synchronously adjusting, by the slave base station, a vibrating frequency of a local crystal oscillator of the slave base station based on frequency synchronization information carried by the CRS.