Network element method for synchronizing time in the mobile communication system
Technical field
The present invention relates to mobile communication technology, relate to or rather in Wideband Code Division Multiple Access (WCDMA) (WCDMA), Time Division-Synchronous Code Division Multiple Access (TD-SCDMA) mobile communication system, absolute time (refers to: the method for synchronous date Hour Minute Second) between the network element in these mobile communication system of base station (NodeB) that the operation maintenance center of radio network controller (OMC-R, below summary is the OMC of operation maintenance center), radio network controller (RNC) and radio network controller (RNC) are managed.
Background technology
In the mobile communication system network element time synchronously for whole communication network, comprise OMC, RNC, the management of NodeB all has very important meaning, when particularly in application, needing to use absolute time,, prior meaning is arranged then such as performance estimation, alarm etc. for system.If the time of network element does not reach synchronously in the communication system, will cause the alarm data between the network element, performance data disorder etc.
" mode of time synchronized in the WCDMA system " (CWTS TSG-RAN WG2meeting # 2002 year) that China wireless technology association (CWTS) passes through, on Iub interface, adopt the SNTP agreement, need realize the server end of SNTP and realize the client of SNTP in the NodeB side in the RNC side, its mode is: RNC is as the higher level time management person of NodeB, all NodeB broadcasting time delays that need to manage to it are termly estimated message, for NodeB estimation time delay.
Time synchronization process is by request and respond two message and finish: NodeB is to RNC transmission delay estimation request message, RNC sends the response response message to NodeB, timestamp information (providing by the SNTP agreement) is provided in this response response message, utilizes timestamp information estimation propagation delay time for NodeB.This timestamp information comprises: original time stabs T1 (Originate Timestamp T1), time of reception stabs T2 (Receive Timestamp T2), transmitting time stamp T3 (Transmit Timestamp T3) and the object time is stabbed T4 (Destination Timestamp T4), NodeB estimates the transmission delay value with these four timestamp informations, is kept at NodeB this locality.Propagation delay time value T Dealy estimation mode is as follows:
T?Dealy=((T4-T1)-(T3-T2))/2。
RNC is airtime message periodically, comprises T_Rnc fiducial time of RNC side in the message;
NodeB adjusts local zone time T_NodeB according to T_Rnc fiducial time of this RNC broadcasting of receiving by following formula:
T_NodeB=T_Rnc+T?Dealy。
Yet in the network configuration of reality, the NodeB number that RNC hangs down can be many, and RNC can increase the system resource spending of RNC to numerous NodeB broadcasting time delay estimation message; Be subjected to the influence of factors such as link reliability and delay variation are big in addition, also may cause the lower timing tracking accuracy of RNC and NodeB between the two.
And, up to now, also there is not in a kind of resolution system the scheme of time synchronized between network elements such as OMC, RNC, NodeB for the TD-SCDMA mobile communication system.
In addition, sub-district in WCDMA and TD-SCDMA system is set up in the process, in order to obtain the timing offset between RNC and NodeB, must be between RNC and NodeB carry out node (in the 3GPP standard specific definition carry out the synchronous content of node between RNC and the NodeB) synchronously in the carrying of high priority.This node synchronizing process can be referring to shown in Figure 1.Estimate request message by Serving RNC (SRNC) to NodeB broadcasting time delay, comprise the moment t1 that sends a request message in the message, the NodeB that receives this time delay estimation request message sends the response response message to Serving RNC, comprise in the response response message that moment t1, moment t2 and the NodeB that NodeB receives this request message that SRNC sends a request message send the moment t3 that responds response message, calculate timing offset for SRNC.
Among Fig. 1, the public frame number counter RFN of SRNS side and the every M microsecond of the public frame number counter BFN of NodeB side (as the M=125 microsecond) add 1, and count range is the 0-327679 microsecond, then circulation.Being produced among Fig. 1 with 10 microseconds is a scale, and its meter full scale is 0-40950 (327680 * 125=40960000 microsecond, 40960 milliseconds).It is synchronous to carry out node by the process that defines in the 3GPP standard between SRNC and the NodeB, obtains the difference DELTA T between node synchronized result: RFN and the BFN.
SRNC is carrying out node when synchronous, obtains the public frame number counter RFN value t1 of SRNC, sends downlink node synchronization frame (DL Node Synchronization), comprises t1=40941.250 in this frame; NodeB writes down the public frame number counter BFN value t2=1492.500 of current NodeB when receiving this frame, the up link node synchronization frame (ULNode Synchrozation) that NodeB replys to the SRNC back response, except comprising t1=40941.250, also comprise t2=1492.500 and the public frame number counter BFN value t3=1505.000 when sending in this frame; SRNC writes down current RFN value t4 when receiving this frame.Thereby draw the difference between RFN and the BFN: Δ T=RFN-BFN=((t4-t3)-(t2-t1))/2 is stored in this value among the RNC.(t2-t1)+(t4-t3) provided round-trip delay shown in the figure.
Summary of the invention
The objective of the invention is to design the network element method for synchronizing time in a kind of mobile communication system, utilize WCDMA and TD-SCDMA system existing, set up in process and other processes in the sub-district, node synchronizing process between RNC and NodeB, promptly utilize the result of this node synchronizing process, realize between network element more high precision time synchronization with very simple method, and reduce the network element expense on time synchronized, the particularly RNC expense on time synchronized.
When the present invention is fiducial time for the time with operation maintenance center, utilize the SNTP agreement to realize allowing fiducial time of radio network controller for fiducial time of operation maintenance center with utilize the node synchronized result realize allowing to be such differentiated control scheme fiducial time of radio network controller the fiducial time of base station.
The technical scheme that realizes the foregoing invention purpose is such: the network element method for synchronizing time in a kind of mobile communication system, be applied in Wideband Code Division Multiple Access (WCDMA) or the mobile communication system of time division synchronization code division multiple access, comprise the time synchronized between operation maintenance center and radio network controller, make the fiducial time that is adjusted into operation maintenance center fiducial time of radio network controller, and the time synchronized between radio network controller and base station, make the fiducial time that is adjusted into radio network controller fiducial time of base station, it is characterized in that the time synchronized between described radio network controller and base station comprises following treatment step:
A1. radio network controller comprises T_Rnc fiducial time of radio network controller side, the public frame number counter RFN value RFN of correspondence this fiducial time of T_Rnc to all base station transmitting time synchronization messages that it descended to hang in the time synchronized message
T_RNC, and the timing offset Δ T that stored, this timing offset Δ T is the difference between the public frame number counter BFN value of the public frame number counter RFN value of radio network controller and base station, and this difference is to calculate according to the node synchronized result that the node synchronizing process between radio network controller and base station obtains;
B1. receive the base station of this time synchronization message, from message, obtain described RFN
T_RNC, described T_Rnc and described timing offset Δ T, described base station obtains the value BFN of its public frame number counter BFN this moment
T_NodeB, utilize T_NodeB=T_Rnc+ ((BFN
T_NodeB+ Δ T)-RFN
T_RNC) * M adjusts its local clock T_NodeB, and M represents that the public frame number counter of described radio network controller and described base station adds 1 counting institute interlude value at every turn in the formula.
Time synchronized between described operation maintenance center and radio network controller makes fiducial time that is adjusted into operation maintenance center fiducial time of radio network controller, comprises following treatment step:
A1. realized the server end of SNTP agreement by operation maintenance center, by the client of radio network controller realization SNTP agreement, radio network controller sends propagation delay time estimation request message to operation maintenance center;
B1. operation maintenance center sends the response response message to radio network controller, in this response response message, comprise timestamp information for radio network controller estimation propagation delay time, this timestamp information comprises: original time stabs T1, time of reception stabs T2, transmitting time stamp T3 and the object time is stabbed T4, radio network controller utilizes T Dealy=((T4-T1)-(T3-T2))/2 to estimate the propagation delay time value, and is kept in the radio network controller;
C1. operation maintenance center comprises T_Omc fiducial time of operation maintenance center's side periodically to radio network controller airtime message in this time message;
D1. radio network controller obtains T_Omc fiducial time of operation maintenance center's side from the time message of receiving, and, press T_Rnc fiducial time that T_Rnc=T_Omc+T Dealy adjusts radio network controller this locality according to the propagation delay time value T Dealy that is estimated.
When the present invention is fiducial time for the time with the base station, utilize the node synchronized result to realize allowing fiducial time of radio network controller for fiducial time of base station with utilize the SNTP agreement realize allowing to be such differentiated control scheme fiducial time of radio network controller the fiducial time of operation maintenance center.
The technical scheme that realizes the foregoing invention purpose is such: the network element method for synchronizing time in a kind of mobile communication system, be applied in Wideband Code Division Multiple Access (WCDMA) or the mobile communication system of time division synchronization code division multiple access, comprise the time synchronized between radio network controller and base station, make the fiducial time that is adjusted into the base station fiducial time of radio network controller, and the time synchronized between operation maintenance center and radio network controller, make the fiducial time that is adjusted into radio network controller fiducial time of operation maintenance center, it is characterized in that the time synchronized between described radio network controller and base station comprises following treatment step:
A2. radio network controller is to message fiducial time of the described a certain base station of a certain base station requests that it descended to hang;
B2. the response response message is returned to radio network controller in this base station, comprise in this response response message the base station fiducial time T_NodeB and corresponding this fiducial time T_NodeB public frame number counter BFN value BFN
T_NodeB
C2. radio network controller obtains described T_NodeB and described BFN from this response response message
T_NodeB, and from described radio network controller self obtain this moment its public frame number counter RFN value RFN
T_RNCAnd the timing offset Δ T that is stored, this timing offset Δ T is the difference between the public frame number counter BFN value of the public frame number counter RFN value of radio network controller and this base station, and this difference is to calculate according to the node synchronized result that the node synchronizing process between radio network controller and described base station obtains;
D2. radio network controller utilizes T_Rnc=T_NodeB+ ((RFN
T_RNC-Δ T)-BFN
T_NodeB) * M, T_Rnc adjusts to its local clock, and M represents that the public frame number counter of described radio network controller and described base station adds 1 counting institute interlude value at every turn in the formula.
Time synchronized between described operation maintenance center and radio network controller makes fiducial time that is adjusted into radio network controller fiducial time of operation maintenance center, comprises following treatment step:
A2. realized the server end of SNTP agreement by radio network controller, by the client of the realization SNTP of operation maintenance center agreement, operation maintenance center sends propagation delay time estimation request message to a radio network controller;
B2. this radio network controller sends the response response message to operation maintenance center, in this response response message, comprise timestamp information for operation maintenance center's estimation propagation delay time, this timestamp information comprises: original time stabs T1, time of reception stabs T2, transmitting time stamp T3 and the object time is stabbed T4, operation maintenance center utilizes T Dealy=((T4-T1)-(T3-T2))/2 to estimate the propagation delay time value, and is kept in the operation maintenance center;
C2. radio network controller comprises T_Rnc fiducial time of radio network controller side periodically to operation maintenance center's transmitting time message in this time message;
D2. operation maintenance center obtains T_Rnc fiducial time of radio network controller side from the time message of receiving, and, press T_Omc fiducial time that T_Omc=T_Rnc+T Dealy adjusts operation maintenance center this locality according to the propagation delay time value T Dealy that is estimated.
The present invention proposes Absolute Time Synchronization method between these network elements of NodeB that OMC, RNC and RNC managed in WCDMA, the TD-SCDMA mobile communication system.
The present invention proposes the method for synchronizing time between RNC and two network elements of NodeB, though with time of operation maintenance center be fiducial time or with time of base station be fiducial time, WCDMA and TD-SCDMA system have all been made full use of in sub-district foundation and other processes, carry out the result that the node synchronizing process is obtained between RNC and NodeB, promptly utilize RNC and the synchronous result of NodeB intermediate node among UMTS, the UTRAN, adopted very simple method to realize more high precision time synchronization again.
The inventive method is utilized the node synchronized result between RNC and NodeB, the timing tracking accuracy height, and needn't strictness limit the propagation delay time that ATM carries IP (IpoA:IP Over ATM) passage.
In WCDMA and TD-SCDMA system, RNC and NodeB intermediate node synchronizing process are carried out on the transmission bearer of Iub interface high priority, on such transmission bearer, carry out the node synchronizing process, node sync frame transmission time delay is little and delay variation is also little, utilize the node synchronized result as time synchronized basis between network element, precision height.
Because adopt differentiated control, OMC does not need to carry out direct time synchronization process with NodeB.RNC realizes the time synchronized between the RNS network element as the manager of Radio Network System (RNS).Thereby simplified the time synchronization process between OMC and NodeB.
In time synchronization process, interacting message between RNC and the NodeB adopts internal system message, can the simplified system processing procedure, be convenient to realize.
The realization of the inventive method is owing to must use the time synchronized result of RNC and NodeB, so do not carry out under the synchronous situation of node at RNC and NodeB, the method for synchronizing time of RNC of the present invention and NodeB can't use.
In sum, method of the present invention realizes that simple, timing tracking accuracy high (especially the timing tracking accuracy between RNC and NodeB is at Millisecond, and error can be far smaller than 1 second), the expense of network element (especially RNC) aspect time synchronized are little.
Description of drawings
Fig. 1 is the node synchronizing process schematic diagram between RNC and NodeB;
Fig. 2 is the FB(flow block) of RNC and NodeB time synchronization process first embodiment;
Fig. 3 is the FB(flow block) of RNC and NodeB time synchronization process two embodiment;
Fig. 4 is the lexical or textual analysis schematic diagram that RNC and NodeB calculate lock in time.
Embodiment
Time synchronized between network element of the present invention comprises time synchronized between OMC and the RNC and the time synchronized between RNC and the NodeB.
The present invention adopts the SNTP agreement to carry out synchronously to the time synchronized of OMC and RNC.
When the time with OMC was fiducial time, OMC realized the server end of SNTP, and RNC realizes the client of SNTP.
In the time synchronized to the estimation of propagation delay time by request with respond two message and finish: RNC is to OMC forward delay interval estimation request message, OMC sends the response response message to RNC, in this response response message, comprise timestamp information, utilize timestamp information estimation transmission delay for RNC.This timestamp information comprises: original time stabs T1 (Originate Timestamp T1), time of reception stabs T2 (ReceiveTimestamp T2), transmitting time stamp T3 (Transmit Timestamp T3) and the object time is stabbed T4 (Destination Timestamp T4), RNC estimates the propagation delay time value with these four timestamp informations, is kept at RNC this locality.Transmission delay value T Dealy estimation mode is as follows:
T?Dealy=((T4-T1)-(T3-T2))/2。
OMC is airtime message periodically, comprises T_Omc fiducial time of OMC side in the message;
RNC adjusts local time T _ Rnc according to the airtime T_Omc of this OMC that receives and the transmission delay value T Dealy of calculating.RNC is as the higher level time management person of NodeB, and the local zone time of this RNC is exactly the fiducial time of RNC side.RNC adjusts local zone time T_Rnc by following formula:
T_Rnc=T_Omc+T?Dealy。
Above-mentioned time synchronized to OMC-R and RNC is consistent with RNC that is introduced in the background technology and the time synchronizing method between the NodeB.
When the time with NodeB is fiducial time, (realize the time synchronized of RNC and NodeB earlier), utilize the SNTP agreement to realize the time synchronized of RNC and OMC.
In the time synchronized to the estimation of propagation delay time by request with respond two message and finish: the server end of realizing the SNTP agreement by radio network controller, by the client of the realization SNTP of operation maintenance center agreement, operation maintenance center sends propagation delay time estimation request message to a radio network controller.
This radio network controller sends the response response message to operation maintenance center, in this response response message, comprise timestamp information for operation maintenance center's estimation propagation delay time, this timestamp information comprises: original time stabs T1, time of reception stabs T2, transmitting time stamp T3 and the object time is stabbed T4, operation maintenance center utilizes T Dealy=((T4-T1)-(T3-T2))/2 to estimate the propagation delay time value, and is kept in the operation maintenance center.
Radio network controller comprises T_Rnc fiducial time of radio network controller side periodically to operation maintenance center's transmitting time message in this time message.
Operation maintenance center obtains T_Rnc fiducial time of radio network controller side from the time message of receiving, and according to the propagation delay time value T Dealy that is estimated, presses T_Omc fiducial time that T_Omc=T_Rnc+T Dealy adjusts operation maintenance center this locality.
The time synchronized of RNC and NodeB.
If the time with OMC is fiducial time, this NodeB then carries out time synchronized with RNC according to the methods below.
Before carrying out time synchronized, the OM channel between RNC and the NodeB is set up.It is synchronous to have carried out node between NodeB and the RNC, RNC has obtained node synchronized result t1, t2, t3, the t4 between RNC and NodeB, has calculated and stored the difference DELTA T (timing offset) between RNC side public frame number Counter Value RFN and the public frame number Counter Value of NodeB side BFN.
RNC periodically or the instruction of accepting operation maintenance center carry out time synchronized.Periodically carrying out time synchronized with RNC is the example explanation.
RNC comprises T_Rnc fiducial time (RNC is fiducial time with the time of RNC side) of RNC side regularly to all NodeB transmitting time synchronization messages of descending extension in the time synchronized message, and the public frame number counter RFN value RFN of correspondence this fiducial time of T_Rnc
T_RNCAnd the timing offset Δ T of public frame number counter RFN and BFN between RNC that is stored and NodeB;
Receive the NodeB of this time synchronization message, from message, obtain the RFN of RNC
T_RNC, and this RFN
T_RNCThe T_Rnc and timing offset Δ T fiducial time of corresponding RNC, NodeB obtains the value BFN of its public frame number counter BFN at this moment
T_NodeB, according to the above value that obtains, NodeB adjusts its local clock T_NodeB, and the adjustment mode is as follows:
T_NodeB=T_Rnc+((BFN
T_NodeB+ΔT)-RFN
T_RNC)×Mμs。The public frame number counter RFN of RNC and the public frame number counter BFN of NodeB add 1 counting every the M microsecond, as M=125 μ s.
Otherwise, if with time of NodeB be benchmark (as by NodeB, with GPS information as time reference) with GPS, also be can be by above method, time (seeing Fig. 3 and explanation thereof) of NodeB and RNC synchronously.
Referring to Fig. 2, the time synchronized flow process between RNC and NodeB on the Iub interface has been described among the figure, this flow process be NodeB do not have GPS or GPS is arranged but GPS information not as the flow process of network element time synchronization basic standard during the time.
Step 21, when beginning to carry out time synchronized, RNC obtains the node synchronizing information that obtains when node is synchronous: t1, t2, t3, t4;
Step 22 is obtained according to four node synchronizing information t1, t2, t3, the RFN of t4 calculating and the timing offset Δ T between BFN;
Step 23, RNC broadcast its fiducial time T_Rnc and corresponding this fiducial time T_Rnc public frame number counter RFN value RFN
T_RNC, and timing offset Δ T;
Step 24, NodeB receives this time synchronization message, obtains the RFN of RNC from message
T_RNC, and this RFN
T_RNCThe T_Rnc and timing offset Δ T fiducial time of corresponding RNC, NodeB obtains the value BFN of its public frame number counter BFN at this moment
T_NodeB, according to the above value that obtains by formula:
T_NodeB=T_Rnc+ ((BFN
T_NodeB+ Δ T)-RFN
T_RNC) * M μ s, T_NodeB adjusts to its local clock.The public frame number counter RFN of RNC and the public frame number counter BFN of NodeB add 1 counting every the M microsecond, as M=125 μ s.
Referring to Fig. 3, the time synchronized flow process between RNC and NodeB on the Iub interface has been described among the figure, be NodeB has GPS and uses GPS information as the network element time synchronized flow process of fiducial time.
Step 31, when beginning to carry out time synchronized, RNC obtains the node synchronizing information that obtains when node is synchronous: t1, t2, t3, t4;
Step 32, RNC obtains according to four node synchronizing information t1, t2, t3, the RFN of t4 calculating and the timing offset Δ T between BFN;
Step 33, RNC to certain NodeB ask this NodeB fiducial time T_NodeB and corresponding this fiducial time T_NodeB public frame number counter BFN value BFN
T_NodeB
Step 34, RNC receives the response message that NodeB returns, from response message, obtain NodeB fiducial time T_NodeB and corresponding this fiducial time T_NodeB public frame number counter BFN value BFN
T_NodeB, obtain the value RFN of the public frame number counter RFN of RNC this moment
T_RNC, and timing offset Δ T, according to the above value that obtains by formula:
T_Rnc=T_NodeB+ ((RFN
R_RNC-Δ T)-BFN
T_NodeB) * M μ s, T_Rnc adjusts to its local clock.The public frame number counter RFN of RNC and the public frame number counter BFN of NodeB add 1 counting every the M microsecond, as M=125 μ s.
Referring to Fig. 4, RNC and NodeB computing formula lock in time are made an explanation.
Suppose that at first the time deviation between RNC and the NodeB is Δ T, when downlink transfer time delay and uplink time delay all are d/2, then:
t2=(t1-ΔT)+d/2
t4=(t3+ΔT)+d/2
Carrying out simple fortran then has:
(t4-t3)=ΔT+d/2
(t2-t1)=-ΔT+d/2
((t4-t3)-(t2-t1))/2=((ΔT+d/2)-(-ΔT+d/2))/2
=(2×ΔT)/2=ΔT
In WCDMA system and the TD-SCDMA system, the network element time synchronized comprises time synchronized between OMC and RNC and the time synchronized between RNC and NodeB.For example do not adopt under the situation of GPS at NodeB, system is a benchmark with the time of OMC, by the time synchronized between OMC and RNC, allows the RNC be benchmark with the time of OMC, again by the time synchronized between RNC and NodeB, allows the NodeB be benchmark with the time of RNC.Adopt at NodeB under the situation of GPS, NodeB is a benchmark with GPS information, and the time synchronized between RNC and NodeB does not then need the time synchronized between OMC and RNC, by the time synchronized between RNC and NodeB, allow the RNC be benchmark, just can allow the OMC be benchmark then with the time of RNC with the time of NodeB.In the time synchronization process of realizing between RNC and NodeB, all fully used node synchronizing information and the timing offset result thereof who in the node synchronizing process, obtains between RNC and NodeB.
Method of the present invention is not limited to the Absolute Time Synchronization between the such network element of OMC in the network, RNC, NodeB, and the Absolute Time Synchronization in the network system between other network elements also can be carried out with reference to the spirit of the inventive method.