CN103874153A - Control method and base stations - Google Patents
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Abstract
The embodiment of the invention provides a control method and base stations. The control method comprises the following steps of during the process of switching a first base station to a second base station on a terminal, searching for a second access preamble which is sent by the terminal, and measuring a timing advance TA3 of the terminal; obtaining a timing advance TA2, measured by the second base station, of the terminal by the first base station, and according to the pre-switched timing advances TA1, TA2 and TA3 of the terminal, calculating a time deviation T between the first base station and the second base station; finally, adjusting a clock according to the T or sending the T to the second base station by the first base station, so that the second base station adjusts the clock according to the T, or when the T is greater than a first threshold value, the first base station turns off a transceiver. According to the control method and the base stations, the avoidance of inter-base-station interference can be realized by adjusting the clock to realize inter-base-station synchronization or by turning off the transceiver, so that the communication quality is guaranteed.
Description
Technical Field
The present invention relates to the field of communications technologies, and in particular, to a control method and a base station.
Background
Long Term Evolution (LTE) is a third generation mobile communication technology (The 3)rdEvolution technology of Generation Telecommunication,3G), LTE includes two Duplex modes, i.e., Time Division Duplex (TDD) and Frequency Division Duplex (FDD), both of which utilize a plurality of new technologies for communication between a base station and a terminal, such as: coordinated multipointThe new technologies include transmission (Coordinated Multiple Points, CoMP), Inter-Cell Interference Coordination (ICIC), Coordinated Scheduling and Power Control (CSPC), and the like, which have high requirements for synchronization of a base station clock.
At present, the LTE system utilizes the global positioning system to implement clock synchronization between base stations, and the specific implementation process is as follows: each base station in the LTE system includes a Global Positioning System (GPS) receiving module, which is used to receive a GPS signal, extract a clock signal from the GPS signal, input the extracted clock signal to a clock phase-locked loop of the base station, and synchronously generate a base station clock through the clock phase-locked loop. Therefore, all base stations use the GPS clock as a clock reference source to realize clock synchronization among the base stations. This solution is very limited in its application because of the high installation and maintenance costs of the GPS equipment. In the prior art, when a base station has no GPS receiving module or the GPS receiving module fails, the base station is likely to cause interference to other base stations.
Disclosure of Invention
The invention provides a control method and a base station, which are used for solving the technical problem that the existing base station is easy to cause interference to other base stations when a GPS receiving module is not arranged or the GPS receiving module fails.
Therefore, the invention provides the following technical scheme:
in a first aspect, an embodiment of the present invention provides a control method, where the method includes:
a first base station acquires a first time advance TA1 of a terminal, wherein the first base station is a source base station of the terminal;
the first base station sends a switching request to a second base station, receives a switching message of the second base station responding to the switching request, and sends the switching message to the terminal, wherein the switching message comprises an identifier of a second access sequence, and the second base station is a target base station of the terminal;
the first base station searches a second access sequence sent to the second base station by the terminal after receiving the switching message according to the identifier of the second access sequence, and then measures a third timing advance TA3 of the terminal;
the first base station acquires a second timing advance TA2 of the terminal, wherein the TA2 is measured by the second base station after receiving the second access sequence;
the first base station determining a time offset, T, between the first base station and the second base station from the TA1, TA2, and TA 3;
and the first base station adjusts the clock of the first base station according to the T, or the first base station sends the T to the second base station, so that the second base station adjusts the clock of the first base station according to the T, or the first base station closes the transceiver when the T is larger than a first threshold value.
In a first possible implementation manner of the first aspect, TA1 of the terminal is measured by the first base station when it is determined that the terminal needs to be handed over to the second base station; or,
TA1 of the terminal is saved when the first base station periodically receives the access sequence transmitted by the terminal.
With reference to the first aspect or the first possible implementation manner of the first aspect, in a second possible implementation manner, the searching, by the first base station, the second access sequence, sent to the second base station by the terminal after receiving the handover message according to the identifier of the second access sequence includes:
after receiving a handover message of the second base station responding to the handover request, the first base station extracts the identification of the second access sequence from the handover message;
and the first base station searches the second access sequence which is sent to the second base station by the terminal after receiving the switching message according to the extracted identifier of the second access sequence.
With reference to the first aspect or the first or second possible implementation manner of the first aspect, in a third possible implementation manner of the first aspect, when the first base station and the second base station use the same access channel, the first base station searches for the second access sequence in the access channel; or,
when the first base station and the second base station adopt different access channels, the first base station acquires the information of the access channel of the second base station from a network management server, and then searches the second access sequence in the access channel of the second base station.
With reference to the first aspect or the first or second or third possible implementation manner of the first aspect, in a fourth possible implementation manner of the first aspect, the first base station determines the T by using the following formula:
T=TA3-(TA2+TA1)/2。
with reference to the first aspect or the first or second or third or fourth possible implementation manner of the first aspect, in a fifth possible implementation manner of the first aspect, the adjusting a clock according to the T includes:
when the T is larger than or equal to a second threshold value, adjusting the phase of the phase-locked loop according to the T; or,
and when the T is smaller than a second threshold value, adjusting the oscillation frequency of the phase-locked loop oscillator according to the T.
With reference to the first aspect or the first or second or third or fourth or fifth possible implementation manner of the first aspect, in a sixth possible implementation manner of the first aspect, the adjusting, by the first base station, the clock according to the T includes:
the first base station measuring a first time offset between the first base station and a third base station and a second time offset between the first base station and a fourth base station;
the first base station calculates the difference between any two items of the T, the first time deviation and the second time deviation;
and when the difference value between the T and the first time deviation is smaller than a third threshold value, the first base station adjusts the clock according to the T.
In a second aspect, an embodiment of the present invention further provides a base station, including:
a first obtaining unit, configured to obtain a first timing advance TA1 of a terminal, where the base station is a source base station of the terminal;
a handover processing unit, configured to send a handover request to a second base station, receive a handover message from the second base station in response to the handover request, and send the handover message to the terminal, where the handover message includes an identifier of a second access sequence, and the second base station is a target base station of the terminal;
a searching unit, configured to search, according to the identifier of the second access sequence, the second access sequence that is sent to the second base station by the terminal after receiving the handover message;
a measuring unit, configured to measure a third timing advance TA3 of the terminal after the second access sequence is searched;
a second obtaining unit, configured to obtain a second timing advance TA2 of the terminal, where the TA2 is measured by the second base station after receiving the second access sequence;
a determining unit configured to determine a time offset T between the first base station and the second base station according to the TA1, TA2, and TA 3;
and an adjusting unit, configured to adjust a clock according to the T, or send the T to the second base station, so that the second base station adjusts the clock according to the T, or, when the T is greater than a first threshold, turns off a transceiver of the base station.
In a first possible implementation manner of the second aspect, the first obtaining unit is specifically configured to measure a first time advance TA1 of the terminal when it is determined that the terminal needs to be handed over to the second base station; or, specifically, the method is configured to obtain the first time advance TA1 of the terminal from the time advances saved when the base station periodically receives the access sequence sent by the terminal.
With reference to the second aspect or the first possible implementation manner of the second aspect, in a second possible implementation manner of the second aspect, the search unit includes:
an extracting subunit, configured to, after receiving a handover message of the second base station in response to the handover request, extract an identifier of the second access sequence from the handover message;
and the searching subunit is configured to search, according to the extracted identifier of the second access sequence, the second access sequence that is sent to the second base station by the terminal after receiving the handover message.
With reference to the second aspect or the first or second possible implementation manner of the second aspect, in a third possible implementation manner of the second aspect, the searching unit is specifically configured to search for the second access sequence in the access channel when the base station and the second base station use the same access channel; or, the second access sequence is specifically configured to, when the base station and the second base station use different access channels, obtain information of the access channel of the second base station from a network management server, and then search for the second access sequence in the access channel of the second base station.
With reference to the second aspect or the first, second, or third possible implementation manner of the second aspect, in a fourth possible implementation manner of the second aspect, the determining unit determines T by using the following formula:
T=TA3-(TA2+TA1)/2。
with reference to the second aspect or the first or second or third or fourth possible implementation manner of the second aspect, in a fifth possible implementation manner of the second aspect, the adjusting unit includes:
the phase adjusting subunit is used for adjusting the phase of the self phase-locked loop according to the time deviation when the time deviation is greater than or equal to a second threshold value; or,
and the frequency adjusting subunit is used for adjusting the oscillation frequency of the phase-locked loop oscillator according to the time deviation when the time deviation is smaller than a second threshold value.
With reference to the second aspect or the first or second or third or fourth or fifth possible implementation manner of the second aspect, in a sixth possible implementation manner of the second aspect, the adjusting unit includes:
the measuring subunit is used for measuring a first time deviation between the base station and a third base station and a second time deviation between the base station and a fourth base station;
a calculating subunit, configured to calculate a difference between every two arbitrary terms of the T, the first time offset, and the second time offset;
and the adjusting subunit is used for adjusting the clock according to the T when the difference value between the T and the first time deviation is smaller than a third threshold value.
In the technical scheme of the control method, when a first base station finds that a terminal needs to be switched, a first time advance (TA 1) of the terminal is obtained, a switching request is sent to a second base station, a switching message of the second base station responding to the switching request is received, and the switching message is sent to the terminal, wherein the switching message comprises an identifier of a second access sequence, and the first base station and the second base station are a source base station and a target base station of the terminal respectively; after receiving the switching message, the terminal sends a second access sequence to a second base station; the second base station receives a second access sequence and measures a second time advance TA2 of the terminal; in the process, the first base station searches for a second access sequence, and measures a third timing advance TA3 of the terminal; finally, the first base station determines the time deviation T between the first base station and the second base station according to TA1, TA2 and TA3, and adjusts the clock according to the T, or the first base station sends the T to the second base station, so that the second base station adjusts the clock according to the T, or when the T is larger than a first threshold value, the first base station turns off the transceiver. In the scheme of the invention, the base station takes clocks of other base stations (such as adjacent base stations) as clock reference sources, and the clocks are adjusted by utilizing the time deviation among the base stations, so that the clock synchronization among the base stations or the timely and accurate closing of the transceiver can be realized when the base stations do not have a GPS receiving module or the GPS receiving module has a fault, the interference among the base stations is avoided, and the communication quality is ensured.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.
FIG. 1 is a flowchart of an embodiment 1 of a control method according to an embodiment of the present invention;
fig. 2 is a schematic diagram of LTE system base station measurement TA;
FIG. 3 is a diagram illustrating a first base station measuring a time offset T according to an embodiment of the present invention;
fig. 4 is a structural diagram of embodiment 1 of a base station of the embodiment of the present invention;
fig. 5 is a hardware configuration diagram of a base station according to an embodiment of the present invention.
Detailed Description
In order to make the technical field of the invention better understand the scheme of the invention, the following detailed description of the embodiments of the invention is provided in conjunction with the accompanying drawings and the implementation mode.
Referring to fig. 1, there is shown a flow chart of an embodiment 1 of a control method of an embodiment of the present invention, the method including:
step 101, a first base station acquires a first timing advance TA1 of a terminal, where the first base station is a source base station of the terminal.
In an LTE system, Timing Advance (TA) is a parameter used to characterize a Timing offset of data sent by a User Equipment (UE) received by a base station, that is, a time for the base station to prompt the UE to send a signal in Advance. In this embodiment, the base station instructs the UE to send an uplink demodulation reference signal or a monitoring reference signal at a specific time point (i.e., a certain subframe), and obtains a TA through timing measurement to maintain uplink synchronization. Of course, the base station may periodically measure and update the TA of the UE, or may randomly transmit an access command to the UE and then measure the TA of the UE (also referred to as the TA corresponding to the UE). After the TA is obtained through measurement, the base station issues the TA to the UE through a Physical Downlink Shared Channel (PDSCH) in a Timing advance command (Timing advance command) manner, so that the UE adjusts its uplink time reference according to the TA, thereby maintaining uplink synchronization between the UE and the base station.
Optionally, the base station may measure the TA of the UE in the following manner, and the specific process is: when a UE accesses a network or when the UE is ready to switch, a pseudo Random Access sequence (Random Access preamble) is sent to a base station at a designated location Of an air interface frame (i.e., a Physical Random Access Channel (PRACH)), the base station searches for an Access sequence sent by the UE in the Access Channel, and calculates a Time advance TA value Of the UE according to an Arrival Time (TOA) Of the Access sequence. Referring to fig. 2, a diagram of a base station measuring TA in an LTE system is shown.
The LTE protocol specifies that when the UE sends the access sequence, the UE determines the start point of the uplink frame with TA as 0, and sends the start point at a specified position of the access channel (Δ T is delayed from the header of the uplink frame, and Δ T is specified in the protocol and is not described herein). The time reference of the base station for measuring the time of arrival (TOA) of the access sequence is the sending time of the head of the uplink frame, and the relation between the TA to be measured and the TOA is as follows: TOA = TA/2+ Δ T + TA/2, i.e. TA = TOA- Δ T.
In this step, TA1 of the terminal is measured by the first base station when it is determined that the terminal needs to be handed over to the second base station; the specific process of the first base station measuring TA1 of the terminal is as follows: and the first base station sends an access command to the terminal when judging that the terminal needs to be switched to the second base station, wherein the access command comprises an identifier of a first access sequence distributed to the terminal by the first base station. After the terminal receives an access command, the terminal sends a first access sequence to the first base station, the first base station receives the first access sequence sent by the terminal, and then measures TA1 of the time advance of the terminal to be switched.
Since the first base station may periodically measure and store the timing advance of the terminal, TA1 of the terminal may also be stored when the first base station periodically receives the access sequence transmitted by the terminal. Therefore, the first base station only needs to extract the TA1 of the terminal from the saved timing advance.
102, the first base station sends a handover request to a second base station, receives a handover message of the second base station responding to the handover request, and sends the handover message to the terminal, where the handover message includes an identifier of a second access sequence, and the second base station is a target base station of the terminal;
optionally, the scenario in which the base station initiates the handover in the LTE system includes the following three types:
(1) the reason for such handover based on the handover of the radio channel quality is: the measurement report of the UE shows that there is a neighbor cell with better channel quality than the current serving cell.
(2) Handover based on radio access technology coverage, the reasons for such handover are: a situation where the UE loses coverage of the current wireless system and thus connects to another wireless system. For example, if a UE is far away from a city area and loses TD-LTE coverage, the network may switch to a network with poor quality detected by the UE, such as Universal Mobile Telecommunications System (UMTS) or Global System for Mobile communications (GSM).
(3) Handover based on load situation, such handover is used to try to balance load conditions between different Radio Access Technologies (RATs) belonging to the same operator when a given cell is overloaded. For example, if one TD-LTE cell is very congested, some users may need to be transferred to a neighboring TD-LTE cell or a neighboring UMTS cell.
In an example of any of the above cases, the first base station needs to handover the terminal to the second base station, and first sends a handover request to the second base station through a Mobility Management Entity (MME), where the handover request may include: the terminal identification, the switching type, the switching reason, the second base station identification and the like. The handover request may further include: the source base station physical layer identification and the message authentication verification code are used for a recovery process after possible switching failure. Then, after receiving the handover request, the second base station allocates an identifier of an access sequence to the terminal, and sends a handover message to the first base station through the MME, where the first base station sends the handover message to the terminal in a transparent transmission manner, where the handover message may include: the identifier of the second base station, the bandwidth of the carrier frequency point, the configuration of the wireless resource, the identifier of the second access sequence, the configuration of the access channel and the like.
Optionally, in the above step, after receiving the handover message of the second base station in response to the handover request, the first base station extracts the identifier of the second access sequence from the handover message, so as to prepare for a subsequent step in which the first base station searches for the second access sequence that is sent to the second base station by the terminal after receiving the handover message. And when the first base station executes the searching operation, generating a corresponding second access sequence according to the extracted identifier of the second access sequence, and then determining whether the searched information is the second access sequence.
Step 103, the first base station searches for the second access sequence sent to the second base station by the terminal after receiving the handover message according to the identifier of the second access sequence, and then measures a third timing advance TA3 of the terminal.
Optionally, the step may include: after receiving a handover message of the second base station responding to the handover request, the first base station extracts the identification of the second access sequence from the handover message; and the first base station searches the second access sequence which is sent to the second base station by the terminal after receiving the switching message according to the extracted identifier of the second access sequence.
After extracting the identifier of the second access sequence allocated to the terminal by the second base station, the first base station generates a corresponding second access sequence according to the identifier, so that technical preparation is provided for the search operation in this step, after the first base station sends a handover message to the terminal, the first base station starts to perform search, after information is searched, whether the information is the second access sequence is compared, if so, the third timing advance TA3 of the terminal is measured according to the arrival time of the second access sequence, and the measurement process may refer to the measurement process shown in fig. 2, which is not described herein again.
Optionally, in actual deployment of the LTE system, different base stations may use the same access channel, or may use different access channels. Therefore, the searching for the second access sequence, which is sent by the terminal to the second base station after receiving the handover message, by the first base station may include different situations, for example:
when the first base station and the second base station adopt the same access channel, the first base station searches the second access sequence in the access channel; or,
when the first base station and the second base station adopt different access channels, the first base station acquires the information of the access channel of the second base station from a network management server, and then searches the second access sequence in the access channel of the second base station.
The two base stations adopt the same access channel, namely that the time domain and the frequency domain positions of the access channels adopted by the two base stations are the same, and the two base stations adopt different access channels, namely that the time domain and/or the frequency domain positions of the access channels adopted by the two base stations are different. The base station allocates an access channel to the terminal, so that the terminal is accessed to the base station through the access channel, that is, the base station indicates which time slot of which frequency point the terminal accesses the base station.
Step 104, the first base station obtains a second timing advance TA2 of the terminal, where TA2 is measured by the second base station after receiving the second access sequence.
Optionally, after receiving the handover message sent by the first base station, the terminal generates a second access sequence according to an identifier of the second access sequence, in general, different identifiers correspond to different algorithms, and the terminal generates the second access sequence according to the algorithm corresponding to the identifier, and then sends the second access sequence to the second base station through an access channel of the second base station. And after receiving the second access sequence sent by the terminal, the second base station measures a second timing advance TA2 of the terminal according to the arrival time of the second access sequence. The first base station sends a request for acquiring the second time advance to the second base station, and then the second base station sends the TA2 to the first base station.
Step 105, the first base station determines a time offset T between the first base station and the second base station according to the TA1, TA2 and TA 3.
The first base station may calculate the time offset T according to the formula T = TA3- (TA2+ TA 1)/2. Referring specifically to fig. 3, a schematic diagram of the first base station measuring the time offset T according to the embodiment of the present invention is shown.
A time advance TA1 obtained by the first base station before the terminal is switched;
TA2 measured by the second base station;
the time for the first base station to search the second access sequence is T2+ TA2/2+ Δ T + TA1/2, and the arrival time of the second access sequence measured by the first base station is as follows: TOA1= (T2+ TA2/2+ Δ T + TA1/2) -T1, calculate timing advance TA 3:
TA3=TOA1-ΔT=(T2+TA2/2+ΔT+TA1/2)-T1-ΔT=T2-T1+(TA2+TA1)/2
thus, the time offset between the first base station and the second base station is:
T=T2-T1=TA3-(TA2+TA1)/2。
if the first base station is closer to the deployment position of the second base station, TA2= TA1 may be considered, and therefore, the first base station does not need to acquire TA2 from the second base station, and the first base station may directly calculate the time offset T according to TA1 acquired by itself and TA3 obtained through measurement, and according to T = TA3-TA 1.
Step 106, the first base station adjusts the clock according to the T, or the first base station sends the T to the second base station, so that the second base station adjusts the clock according to the T, or when the T is greater than a first threshold, the first base station turns off the transceiver.
For the first base station, the self clock may be adjusted according to the T, that is, the first base station uses the clock of the second base station as a clock reference source, and adjusts the self clock by using the time deviation between the two, so as to implement clock synchronization between the base stations, thereby ensuring that the base stations do not interfere with each other. Furthermore, the first base station may further send the T to the second base station, so that the second base station adjusts the clock according to the T, and then, for the second base station, the clock of the first base station is used as a clock reference source, and the clock of the second base station is adjusted by using the time deviation between the first base station and the second base station, so as to implement clock synchronization between the base stations, thereby ensuring that the base stations do not interfere with each other.
In addition, the first base station can determine whether the clock of the first base station fails by judging whether the time deviation T between the first base station and the second base station is greater than a first threshold value, and if the T is greater than the first threshold value, it indicates that the clock of the first base station fails.
Since the clock variation may affect the communication quality during the clock adjustment of the base station, the present invention provides the following preferable solution to solve this problem.
Preferably, the adjusting the clock according to the T may include: when the T is larger than or equal to a second threshold value, adjusting the phase of the phase-locked loop according to the T; or when the T is smaller than a second threshold value, adjusting the oscillation frequency of the phase-locked loop oscillator according to the T.
The unit of the first threshold value may be set to a level of microseconds in the above embodiment, and the unit of the second threshold value may also be set to a level of microseconds; preferably, the value range of the second threshold is 10-30 microseconds; such as: the second threshold value may be preset to 20 microseconds. The first threshold is used for judging whether the current clock fails, namely, the normal work of the base station cannot be ensured in a clock adjustment mode; the second threshold is used to determine which way should be used to adjust the clock, that is, the normal operation of the base station can be ensured by the way of adjusting the clock. Therefore, when setting these two thresholds, the magnitude relationship between them must be considered, and the first threshold should be larger than the second threshold, such as: the first threshold value may be preset to 50 microseconds and the second threshold value may be set to 20 microseconds. In practical applications, the first threshold and the second threshold may be set according to specific accuracy requirements.
In the above preferred embodiment, when T is greater than or equal to the second threshold, it indicates that the clock of the base station is out of synchronization seriously at this time, and the base station must adjust the clock within the shortest time to achieve synchronization, so as to avoid serious interference caused by clock desynchronization. When T is less than the second threshold, it indicates that the clock loss of the base station is not particularly serious, the interference is small, and the communication quality is not seriously affected, so that the base station may slowly adjust the clock, and in order to avoid the problem of communication interruption caused by sudden change of the clock, the base station may adjust the clock by gradually reducing the clock deviation.
In the above embodiment, the first base station may determine the time deviation between the first base station and the second base station according to the TA1 and the TA3 of the terminal measured by the first base station and the TA2 of the terminal measured by the second base station, so as to adjust its clock, or trigger the second base station to adjust the clock, thereby ensuring that clock synchronization can be achieved without a clock reference source provided by a GPS module between the base stations, and thus avoiding interference between the base stations. Or, the first base station can also avoid interference between the base stations by turning off the transceiver.
In order to ensure the accuracy of clock adjustment and the reliability of a judgment result, the embodiment of the invention also provides a preferable scheme, and the preferable scheme determines the reliability of the time deviation T between the first base station and the second base station, and the first base station adjusts the clock of the first base station according to the T under the condition of determining the accuracy of the T, so that the accuracy of clock synchronization between the base stations can be ensured, and the interference between the base stations can be better avoided. This preferred variant is explained below only on the basis of method example 1.
Preferably, the adjusting, by the first base station, the clock according to the T may include:
the first base station measuring a first time offset between the first base station and a third base station and a second time offset between the first base station and a fourth base station;
the first base station calculates the difference between any two items of the T, the first time deviation and the second time deviation;
and when the difference between the T and the first time deviation is smaller than a third threshold or the difference between the T and the second time deviation is smaller than a third threshold, the first base station adjusts the clock according to the T.
Such as: the first base station measures a first time deviation between the first base station and a third base station and a second time deviation between the first base station and a fourth base station, wherein the first time deviation is T1, the second time deviation is T2, the time deviation between the first base station and the second base station is T, and whether the clock of the second base station is accurate is determined by judging the magnitude relation of the three time deviations. The method comprises the following steps: the first base station respectively calculates the difference between any two of the three time deviations, namely, calculates T-T1, T-T2 and T1-T2, then respectively compares the magnitude relation between the absolute value of the three difference values and a third threshold value, if the absolute value of T-T1 is smaller than the threshold value or the absolute value of T-T2 is smaller than the third threshold value, the T can be used for adjusting the clock, and then the accuracy of adjustment can be improved by adjusting the clock by using the T value.
Of course, the third threshold may also be set to a threshold range, so that the first base station only needs to determine whether the three difference values fall within the threshold range, and if T-T2 or T-T2 falls within the threshold range, the first base station may adjust the clock according to T.
Wherein, the unit of the third threshold value can be set to a microsecond level, such as: the value range of the third threshold is 1-10 microseconds, and preferably, the third threshold is set to be 5 microseconds. The third threshold is used to determine whether the time deviation T can be used to adjust the clock, i.e. the accuracy and reliability of the time deviation T, and therefore, the third threshold can be adaptively set according to the requirement of the system on the clock accuracy.
Of course, the first base station may also calculate a ratio between every two of the T, the first time offset, and the second time offset; and when the ratio of the T to the first time deviation is smaller than a fourth threshold or the ratio of the T to the second time deviation is smaller than a fourth threshold, the first base station adjusts the clock according to the T.
Of course, the first base station may also determine a comparison relationship between every two of the T, the first time offset, and the second time offset through other calculation manners; and then, when the comparison relation meets a preset condition, the first base station adjusts the clock according to the T.
Corresponding to the control method of the method embodiment 1, the embodiment of the present invention further provides an implementation manner of the base station, where the base station can implement clock synchronization with other base stations or timely and accurately turn off the transceiver under the condition that there is no GPS module or a failure of the GPS module, so as to avoid interference between the base stations and ensure communication quality.
Referring to fig. 4, a base station may include: a first acquisition unit 201, a switching processing unit 202, a search unit 203, a measurement unit 204, a second acquisition unit 205, a determination unit 206, and an adjustment unit 207. The internal structure and connections of the base station will be further described below in connection with its operation.
A first obtaining unit 201, configured to obtain a first time advance TA1 of a terminal, where the base station is a source base station of the terminal;
a handover processing unit 202, configured to send a handover request to a second base station, receive a handover message of the second base station in response to the handover request, and send the handover message to the terminal, where the handover message includes an identifier of a second access sequence, and the second base station is a target base station of the terminal;
a searching unit 203, configured to search a second access sequence that is sent to the second base station by the terminal after receiving the handover message;
a measuring unit 204, configured to measure a third timing advance TA3 of the terminal after the second access sequence is searched;
a second obtaining unit 205, configured to obtain a second timing advance TA2 of the terminal, where the TA2 is measured by the second base station after receiving the second access sequence;
a determining unit 206 for determining a time offset T between the first base station and the second base station according to the TA1, TA2 and TA 3;
an adjusting unit 207, configured to adjust a clock according to the T, or send the T to the second base station, so that the second base station adjusts the clock according to the T, or, when the T is greater than a first threshold, turns off a transceiver of the base station.
Optionally, the first obtaining unit is specifically configured to measure a first timing advance TA1 of the terminal when it is determined that the terminal needs to be handed over to the second base station; or,
specifically, the method is configured to obtain a first time advance TA1 of the terminal from time advances saved when the base station periodically receives an access sequence sent by the terminal.
Optionally, the search unit includes:
an extracting subunit, configured to, after receiving a handover message of the second base station in response to the handover request, extract an identifier of the second access sequence from the handover message;
and the searching subunit is configured to search, according to the extracted identifier of the second access sequence, the second access sequence that is sent to the second base station by the terminal after receiving the handover message.
Optionally, the searching unit is specifically configured to search the second access sequence in the access channel when the base station and the second base station use the same access channel; or,
the second access sequence is obtained from the network management server, and then the second access sequence is searched for in the access channel of the second base station.
Optionally, the determining unit determines T by using the following formula:
T=TA3-(TA2+TA1)/2。
optionally, the adjusting unit includes:
the phase adjusting subunit is used for adjusting the phase of the self phase-locked loop according to the time deviation when the time deviation is greater than or equal to a second threshold value; or,
and the frequency adjusting subunit is used for adjusting the oscillation frequency of the phase-locked loop oscillator according to the time deviation when the time deviation is smaller than a second threshold value.
It can be seen from the above embodiments that, when there is no GPS module or the GPS module fails, the base station in the embodiment of the present invention can adjust its own clock by measuring the time offset with the second base station in the process of switching the terminal, that is, adjusting its own clock by using the clock of the second base station as a reference clock, or sending the time offset to the second base station to trigger the second base station to adjust its own clock, and implementing clock synchronization between the base stations by adjusting the clocks, thereby avoiding interference between the base stations. In addition, the base station can stop receiving and transmitting signals in a mode of closing the transceiver, so that interference to other base stations is avoided.
In the embodiment 1 of the base station, the base station adjusts the time offset with the second base station as a clock reference source or as a judgment condition for turning off the transceiver, so that the accuracy of the clock of the second base station is very important.
In order to improve the accuracy of the base station adjusting the clock according to the time offset or to improve the reliability of the operation of the transceiver. The present invention also provides a preferred scheme, which is explained below only on the basis of the above-mentioned base station embodiment 1.
Preferably, the adjusting unit may include:
the measuring subunit is used for measuring a first time deviation between the base station and a third base station and a second time deviation between the base station and a fourth base station;
a calculating subunit, configured to calculate a difference between every two arbitrary terms of the T, the first time offset, and the second time offset;
and the adjusting subunit is used for adjusting the clock according to the T when the difference value between the T and the first time deviation is smaller than a third threshold value.
The base station determines the reliability of the time deviation T between the base station and the second base station by comparing the magnitude relation between the time deviations of the base station and the three base stations, so that the processing can not only further determine the accuracy of clock adjustment, but also ensure the reliability of the base station in executing the operation of closing the transceiver.
Further, the embodiment of the present invention also provides a hardware configuration of a base station, where the base station may include at least one processor (e.g., CPU), at least one network interface or other communication interface, a memory, and at least one communication bus, and is used to implement connection communication between these devices. The processor is used to execute executable modules, such as computer programs, stored in the memory. The Memory may be a volatile Memory (volatile Memory) such as a Random Access Memory (RAM), or a non-volatile Memory (non-volatile Memory) such as a Read Only Memory (ROM), a flash Memory (flash Memory), a Hard Disk Drive (HDD), or a Solid State Drive (SSD). The communication connection between the base station and at least one other network element is realized through at least one network interface (which may be wired or wireless), and the internet, a wide area network, a local network, a metropolitan area network and the like can be used.
Referring to fig. 5, in some embodiments, the memory has stored therein executable modules that are executable by the processor, wherein the executable modules include: the first obtaining unit 201, the switching processing unit 202, the searching unit 203, the measuring unit 204, the second obtaining unit 205, the determining unit 206, and the adjusting unit 207 may refer to corresponding units disclosed in fig. 4, and details thereof are not repeated herein.
It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
It should be further noted that, as will be understood by those skilled in the art, all or part of the processes in the methods of the above embodiments may be implemented by a computer program, which may be stored in a computer-readable storage medium, and when executed, may include the processes of the embodiments of the methods described above. The storage medium may be a magnetic disk, an optical disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), or the like.
Furthermore, it should be noted that all the embodiments in this specification are described in a progressive manner, and the same and similar parts among the embodiments may be referred to each other, and each embodiment focuses on the differences from the other embodiments. In particular, for the apparatus and system embodiments, since they are substantially similar to the method embodiments, they are described in a relatively simple manner, and reference may be made to some of the descriptions of the method embodiments for related points. The above-described embodiments of the apparatus and system are merely illustrative, and the units described as separate parts may or may not be physically separate, and the parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of the present embodiment. One of ordinary skill in the art can understand and implement it without inventive effort.
The above detailed description is provided for a control method and a base station provided by the present invention, and the principle and the implementation of the present invention are explained in the present document by applying specific embodiments, and the description of the above embodiments is only used to help understanding the method and the core idea of the present invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, there may be variations in the specific embodiments and the application scope, and in summary, the content of the present specification should not be construed as a limitation to the present invention.
Claims (14)
1. A control method, characterized in that the method comprises:
a first base station acquires a first time advance TA1 of a terminal, wherein the first base station is a source base station of the terminal;
the first base station sends a switching request to a second base station, receives a switching message of the second base station responding to the switching request, and sends the switching message to the terminal, wherein the switching message comprises an identifier of a second access sequence, and the second base station is a target base station of the terminal;
the first base station searches a second access sequence sent to the second base station by the terminal after receiving the switching message according to the identifier of the second access sequence, and then measures a third timing advance TA3 of the terminal;
the first base station acquires a second timing advance TA2 of the terminal, wherein the TA2 is measured by the second base station after receiving the second access sequence;
the first base station determining a time offset, T, between the first base station and the second base station from the TA1, TA2, and TA 3;
and the first base station adjusts the clock according to the T, or the first base station sends the T to the second base station, so that the second base station adjusts the clock according to the T, or the first base station closes the transceiver when the T is larger than a first threshold value.
2. The method of claim 1,
TA1 of the terminal is measured by the first base station when deciding that the terminal needs to be handed over to the second base station; or,
TA1 of the terminal is saved when the first base station periodically receives the access sequence transmitted by the terminal.
3. The method according to claim 1 or 2, wherein the first base station searching for the second access sequence sent by the terminal to the second base station after receiving the handover message according to the identifier of the second access sequence comprises:
after receiving a handover message of the second base station responding to the handover request, the first base station extracts the identification of the second access sequence from the handover message;
and the first base station searches the second access sequence which is sent to the second base station by the terminal after receiving the switching message according to the extracted identifier of the second access sequence.
4. The method according to any one of claims 1 to 3,
when the first base station and the second base station adopt the same access channel, the first base station searches the second access sequence in the access channel; or,
when the first base station and the second base station adopt different access channels, the first base station acquires the information of the access channel of the second base station from a network management server, and then searches the second access sequence in the access channel of the second base station.
5. The method according to any of claims 1 to 4, wherein the first base station determines the T using the following formula:
T=TA3-(TA2+TA1)/2。
6. the method of any of claims 1-5, wherein said adjusting a clock according to said T comprises:
when the T is larger than or equal to a second threshold value, adjusting the phase of the phase-locked loop according to the T; or,
and when the T is smaller than a second threshold value, adjusting the oscillation frequency of the phase-locked loop oscillator according to the T.
7. The method of any one of claims 1 to 6, wherein the first base station adjusting the clock according to the T comprises:
the first base station measuring a first time offset between the first base station and a third base station and a second time offset between the first base station and a fourth base station;
the first base station calculates the difference between any two items of the T, the first time deviation and the second time deviation;
and when the difference value between the T and the first time deviation is smaller than a third threshold value, the first base station adjusts the clock according to the T.
8. A base station, characterized in that the base station comprises:
a first obtaining unit, configured to obtain a first timing advance TA1 of a terminal, where the base station is a source base station of the terminal;
a handover processing unit, configured to send a handover request to a second base station, receive a handover message from the second base station in response to the handover request, and send the handover message to the terminal, where the handover message includes an identifier of a second access sequence, and the second base station is a target base station of the terminal;
a searching unit, configured to search, according to the identifier of the second access sequence, the second access sequence that is sent to the second base station by the terminal after receiving the handover message;
a measuring unit, configured to measure a third timing advance TA3 of the terminal after the second access sequence is searched;
a second obtaining unit, configured to obtain a second timing advance TA2 of the terminal, where the TA2 is measured by the second base station after receiving the second access sequence;
a determining unit configured to determine a time offset T between the first base station and the second base station according to the TA1, TA2, and TA 3;
and an adjusting unit, configured to adjust a clock according to the T, or send the T to the second base station, so that the second base station adjusts the clock according to the T, or, when the T is greater than a first threshold, turns off a transceiver of the base station.
9. The base station of claim 8,
the first obtaining unit is specifically configured to measure a first timing advance TA1 of the terminal when it is determined that the terminal needs to be handed over to the second base station; or,
specifically, the method is configured to obtain a first time advance TA1 of the terminal from time advances saved when the base station periodically receives an access sequence sent by the terminal.
10. The base station according to claim 8 or 9, wherein the searching unit comprises:
an extracting subunit, configured to, after receiving a handover message of the second base station in response to the handover request, extract an identifier of the second access sequence from the handover message;
and the searching subunit is configured to search, according to the extracted identifier of the second access sequence, the second access sequence that is sent to the second base station by the terminal after receiving the handover message.
11. Base station according to any of claims 8 to 10,
the searching unit is specifically configured to search the second access sequence in the access channel when the base station and the second base station use the same access channel; or,
the second access sequence is obtained from the network management server, and then the second access sequence is searched for in the access channel of the second base station.
12. The base station according to any of claims 8 to 11,
the determining unit determines the T using the following formula:
T=TA3-(TA2+TA1)/2。
13. the base station according to any of claims 8 to 12, wherein the adjusting unit comprises:
the phase adjusting subunit is used for adjusting the phase of the self phase-locked loop according to the time deviation when the time deviation is greater than or equal to a second threshold value; or,
and the frequency adjusting subunit is used for adjusting the oscillation frequency of the phase-locked loop oscillator according to the time deviation when the time deviation is smaller than a second threshold value.
14. The base station according to any of claims 8 to 13, wherein the adjusting unit comprises:
the measuring subunit is used for measuring a first time deviation between the base station and a third base station and a second time deviation between the base station and a fourth base station;
a calculating subunit, configured to calculate a difference between every two arbitrary terms of the T, the first time offset, and the second time offset;
and the adjusting subunit is used for adjusting the clock according to the T when the difference between the T and the first time deviation is smaller than a third threshold or the difference between the T and the second time deviation is smaller than a third threshold.
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