CN105790790B - SCH interference elimination method and device under a kind of TSTD mode - Google Patents
SCH interference elimination method and device under a kind of TSTD mode Download PDFInfo
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Abstract
The present invention relates to mobile communication fields, in particular to SCH interference elimination method and its device under a kind of TSTD mode, the method includes CPICH Common Pilot Channel CPICH symbol of the acquisition after balanced, using the CPICH sign estimation from transmitting terminal to signal after equalization sytem matrix experienced, using SCH mode and the sytem matrix reconstruct TSTD mode under SCH signal and eliminated；The present invention reduces real-time operation amounts, reduce amount of storage, improve performance.
Description
Technical field
It is concretely that one kind exists the present invention relates to mobile communication field, in particular to WCDMA and HSPA+ communication system
Synchronous channel SCH is interfered under time-switching transmitting diversity (Time Switched Transmit Diversity, TSTD) mode
Removing method and its device.
Background technique
In WCDMA system and its HSPA+ system of evolution, preceding 256 chip that SCH channel is fixed on every time slot is sent,
It is divided into primary synchronization channel P-SCH and auxiliary synchronization channel S-SCH, is respectively used to the slot synchronization of cell searching, frame synchronization and small
The identification etc. of area's scrambling code group is the important channel in system design.And SCH channel is not spread, before transmitting at scrambling
Reason, with the non-orthogonal property of other channels make SCH channel there are the demodulation performance of strong influence high-order modulating, lead
Cause planisphere after equilibrium at random, when Euclidean distance more temporary influence is more serious between constellation point.
System emulation and it was verified that when Traffic Channel using 16QAM modulate and 64QAM modulation etc. high-order modulatings
When, the presence of SCH is affected to error rate of system BER, by taking 64QAM modulation system as an example, under ecotopia after equilibrium
For planisphere there are still constellation point at random, the BER as caused by SCH is about 1.3% or so, seriously affects when business code rate is higher and is
System handling capacity.If eliminating without interference, the handling capacity of HSPA+21M peak value test example will settle to 5M or so.Therefore, for
In the case that Traffic Channel uses high-order modulating, the interference elimination of SCH channel is required.
TSTD is that synchronization codes and auxiliary synchronous code, example are alternately sent on two antennas according to the odd, even of timeslot number
If even time slot is sent in first antenna, odd time slot is sent in second antenna.When base station is using single transmitting antenna, SCH is held
Continue and emit in transmitting antenna 1, it is relatively easy that model is eliminated in the SCH interference in the case of this；When base station uses two transmitting antennas
(STTD or MIMO), SCH channel use TSTD sending mode, i.e. even timeslots SCH is sent in antenna 1, and odd numbered slots SCH is in day
Line 2 is sent.Signal model becomes complicated at this time, needs to redesign SCH interference cancellation scheme.
Chinese Patent Application No. is 201080049459.0, and publication date is on 07 18th, 2012, and patent name is " mobile
Synchronizing channel (SCH) interference elimination method in communication system ", it discloses the SCH interference in a kind of mobile communication system to disappear
The method removed, mainly comprises the steps that
(a) signal after receiving chip equalization on one or more streams, each signal have in one or more time slots
Multiple chips and CPICH
(b) the PSC mode and SSC mode for P-SCH and S-SCH relevant to signal are generated, 3GPP TS is passed through
25.213 the mode of description generates.
(c) estimate the power of P-SCH and S-SCH
(d) estimation P-SCH is to CPICH and S-SCH to each of CPICH power ratio
(e) SCH interference is carried out in 256 chips of the head of n-th of time slot to eliminate.
Above technical scheme has the following disadvantages:
1) it under TSTD mode, eliminates in the SCH interference that even timeslots only considered antenna 1, only considers in odd numbered slots
The SCH of antenna 2, which is interfered, to be eliminated.Because the equalizing coefficient that two antennas use is different, Data odd time slot is also needed after actual equilibrium
Consider that the SCH interference of antenna 2 is eliminated, odd numbered slots are it is also contemplated that the SCH of antenna 1 is interfered and eliminated, otherwise degradation.
No matter 2) any condition all carries out interference elimination to SCH always, and when bad environments noise compares in practical application
When low, the interference elimination of SCH is often brought a negative impact, and should be eliminated to the interference of SCH and be set certain control condition with certainly
It is fixed whether to carry out interference elimination.
3) need to calculate the SCH mode of current time slots chip in real time in signal receive process, and the SCH mode is for spy
It is fixed for determining cell in fact.
Summary of the invention
In order to solve the problems, such as the above existing SCH interference cancellation techniques, the SCH under a kind of TSTD mode is proposed
Interference elimination method and device avoid SCH under prior art TSTD mode and interfere elimination model is inaccurate, performance is poor to ask
Topic.
A kind of synchronous channel SCH interference elimination method under time-switching transmitting diversity TSTD mode, obtain it is balanced after
CPICH Common Pilot Channel CPICH symbol, using the CPICH sign estimation from transmitting terminal to signal after equalization system square experienced
Battle array using the SCH signal under SCH mode and sytem matrix reconstruct TSTD mode and is eliminated；
The SCH mode by cell search process determination and pre-stored service cell SCH mode, including main synchronization
Channel P-SCH mode and auxiliary synchronization channel S-SCH mode.
Preferably, after system changes scrambling code group in carrying out cell reselection process, new S-SCH mode is prestored again.
Preferably, the SCH mode of pre-stored service cell prestores mode using bit grades.
Preferably, before the CPICH symbol after the acquisition is balanced, including according to historical channel estimated result acquisition two
The Signal to Noise Ratio (SNR) estimated value of transmission antenna determines whether that carrying out SCH interference eliminates according to the SNR estimated value.
Preferably, the CPICH symbol obtained after equilibrium, comprising: after receiving chip equalization on one or more stream
Signal, wherein include it is all receive signals equilibriums after chip flow data；Chip signal after received equilibrium is carried out
The despreading of CPICH channel descrambles, and obtains CPICH symbol.
Preferably, estimation sytem matrix experienced from transmitting terminal to signal after equalization includes only using all the way
CPICH sign computation continuous item obtains SCH signal related coefficient A1_cur, A2_cur, Acrs_cur, by the related coefficient
A1_cur, A2_cur, Acrs_cur carry out alpha filtering respectively and obtain sytem matrix A1, A2, Acrs.
Preferably, described to reconstruct the SCH signal under TSTD mode using SCH mode and the sytem matrix and eliminated
It is carried out in the preceding 256chip of current time slots, and different cancellations is used according to odd even time slot difference.
Synchronous channel SCH interference blanking unit under a kind of time-switching transmitting diversity TSTD mode, comprising:
The pre- storage of SCH mode, for determined in cell search process and pre-stored service cell SCH mode, including
Primary synchronization channel P-SCH mode and auxiliary synchronization channel S-SCH mode；
Chip stream receiver after equilibrium, for receiving the output from chip equalization, when transmitting terminal is single antenna Shi Weidan
The transmission antenna data on road are the transmission antenna data of two-way when transmitting terminal is two antenna；
CPICH de-spreads descrambler, for the spreading code according to current service cell scrambling code ID and CPICH Common Pilot Channel CPICH
Data are received to the chip-level of two transmission antennas and carry out descrambling and de-spreading, obtain two antenna CPICH symbols；
SCH signal related coefficient calculator, for being undergone from transmitting terminal to signal after equalization using CPICH sign estimation
Sytem matrix, i.e., only using CPICH sign computation continuous item all the way obtain SCH signal related coefficient A1_cur, A2_cur,
Acrs_cur, by described related coefficient A1_cur, A2_cur, Acrs_cur carry out respectively alpha filtering obtain sytem matrix A1,
A2、Acrs。
SCH interference eliminator, the SCH mode prestored using the pre- storage of SCH mode and CPICH despreading descrambler are obtained
Sytem matrix reconstructs the SCH signal under TSTD mode and is eliminated.
Preferably, including controller is eliminated in SCH interference, with it is balanced after chip stream receiver be connected, for according to history
Channel estimation results obtain the Signal to Noise Ratio (SNR) estimated value of two transmission antennas, are determined whether to carry out SCH according to the SNR estimated value
Interference is eliminated.
Preferably, the interference of SCH interference eliminator is eliminated carries out in the preceding 256chip of current time slots, and when according to odd even
Gap difference uses different cancellations.
The present invention is only accorded with using CPICH all the way during the SCH continuous item under TSTD mode between multiple antennas generates
Number calculating cross-correlation item reduces operation, for reducing the operand for reconstructing SCH signal；After determining ID in cell searching
The method for prestoring SCH mode reduces real-time operation amount；Further, whether the present invention provides the self-adaptive decision under TSTD mode
The scheme that SCH interference is eliminated is carried out, is avoided the occurrence of when power difference is big between two antennas, the SCH of lower-powered antenna estimates
Meter inaccuracy, elimination may play negative interaction instead, or are equally unsuitable for progress SCH interference when whole noise is relatively low and disappear
It removes, there are negative interaction risks.
Detailed description of the invention
Fig. 1 is the synchronous channel SCH interference elimination method preferred embodiment flow diagram under TSTD mode of the present invention；
Fig. 2 is another preferred embodiment process signal of synchronous channel SCH interference elimination method under TSTD mode of the present invention
Figure；
Fig. 3 is the synchronous channel SCH interference blanking unit preferred embodiment structural schematic diagram under TSTD mode of the present invention；
Fig. 4 is that the synchronous channel SCH interference blanking unit SCH signal related system calculator under TSTD mode of the present invention is excellent
Select example structure schematic diagram；
Fig. 5 is another preferred embodiment structural representation of synchronous channel SCH interference blanking unit under TSTD mode of the present invention
Figure.
Specific embodiment
In order to make the objectives, technical solutions, and advantages of the present invention clearer, with reference to the accompanying drawings and embodiments, right
The present invention is described in further details；The method of the present invention and the embodiment of device can mutually quote confirmation.
SCH interference elimination method under a kind of TSTD mode of the present invention, the CPICH Common Pilot Channel CPICH symbol after obtaining equilibrium
Number, using the CPICH sign estimation from transmitting terminal to signal after equalization sytem matrix experienced, utilize SCH mode and institute
It states the SCH signal under sytem matrix reconstruct TSTD mode and is eliminated.
The SCH mode is the SCH mode for the serving cell for determining and prestoring in cell search process, including main same
Walk channel P-SCH mode and auxiliary synchronization channel S-SCH mode；
It is recorded according to related data, SCH channel design is intended that the time slot for carrying out cell searching using P-SCH channel is same
Step carries out the identification of the frame synchronization and scrambling code group of cell searching using S-SCH channel.
All time slots of all cells of P-SCH channel are all made of identical P-SCH mode, and length 256 is referred to
The synchronous code generating process of 3GPP TS25.213 agreement 5.2.3 chapters and sections generates P-SCH mode and prestores, subsequent to use P-SCH mould
It is directly read when formula.
S-SCH channel uses 64 kinds of different S-SCH modes according to the difference of scrambling code group, in the frame synchronization of cell searching
S-SCH mode is generated in process and scrambling code group identification process, generating mode is referred to 3GPP TS25.213 agreement 5.2.3 chapter
The synchronous code generating process of section carries out pre- in frame synchronization and the S-SCH mode used this cell during disturb code group identification
Deposit, it is subsequent using S-SCH mode when directly read.
Particularly, after system changes scrambling code group in carrying out cell reselection process, new S-SCH mode is prestored again.
The present embodiment is by determining that the method for prestoring SCH mode after ID reduces real-time operation amount in cell searching.It is preferred that
Ground, the SCH mode of the serving cell prestored prestores mode using bit grades, so that the data volume prestored is smaller.
Further, whether the self-adaptive decision that the present invention provides under a kind of TSTD mode carries out the side that SCH interference is eliminated
Case, when power difference is big between two antennas, the SCH of lower-powered antenna estimates inaccuracy, and elimination may be played negative instead
Effect, or be equally unsuitable for carrying out SCH interference elimination when whole noise is relatively low, there are negative interaction risks.
Preferably, before the CPICH symbol after the acquisition is balanced, including according to historical channel estimated result acquisition two
The Signal to Noise Ratio (SNR) estimated value of transmission antenna determines whether that carrying out SCH interference eliminates according to the SNR estimated value.
It specifically includes:
302-1, the current channel impulse response che for receiving data is obtained first1、che2, wherein che1It indicates to send day
The channel estimation results of line 1, che2Indicate the channel estimation results of transmission antenna 2.
che1、che2Estimation can be obtained using general relevant way, estimation mode non-present invention protects content,
It repeats no more.
302-2, then according to the che of acquisition1、che2, Signal to Noise Ratio (SNR) _ est of two transmission antennas is estimated respectively1With
SNR_est2。
Specifically, with che1SNR estimation for, if che1The a length of L of window, then first search for the long range of L window in maximum
The power Max_pwr of diameter distinguishes signal diameter and noise path using the 1/N of Max_pwr as thresholding, accumulating signal diameter power P wr with make an uproar
Sound diameter power Noise obtains the signal-to-noise ratio (SNR) estimation value of the two:
SNR_est=Pwr/Noise
The SNR estimated value SNR_est of two transmission antennas is obtained according to the above aspect1With SNR_est2。
302-2, the SNR estimated value SNR_est according to two transmission antennas1With SNR_est2Interference is judged whether to disappear
It removes:
If SNR_est1< SNR_Th, and SNR_est2< SNR_Th, then current time slots are interfered without SCH and are eliminated, and are directly moved back
Interference cancellation process out.
If the SNR estimated value SNR_est of two transmission antennas1With SNR_est2At least one is greater than SNR_Th, then after carrying out
Continuous SCH, which is interfered, to be eliminated.
The SNR_Th is channel quality thresholds, characterizes the fine or not degree of channel quality, different actual wireless channel rings
Border uses different values.
The present embodiment passes through the received signal quality for judge current antenna and entirety signal-to-noise ratio etc. conditions to whether carrying out SCH
Interference is eliminated and is controlled, and avoids occurring the situation that SCH eliminates inaccuracy under mal-condition.
The CPICH symbol obtained after equilibrium, comprising: the signal after receiving chip equalization on one or more streams,
Wherein include it is all receive signals equilibriums after chip flow data；CPICH channel is carried out to chip signal after received equilibrium
Despreading descrambling, obtain CPICH symbol.
The present invention carries out SCH interference to chip data after equilibrium and eliminates, and is relatively easy to implement in this way, at this time the number after equilibrium
According to the superposition summation after spreading, scrambling for all code channels.Since remaining code channel is spread using different ovsf codes, mutual
Orthogonality is guaranteed, and the corresponding symbol sent can be obtained after carrying out descrambling and de-spreading to data after equilibrium.And SCH channel is being sent out
Sending end is not scrambled, is spread, and due to nonorthogonality, it influences the despreading of other code channel data descrambling serious, and the present invention is exactly benefit
With this feature, SCH channel is eliminated here.
This step receives the output from chip equalization module, when transmitting terminal is single antenna, after chip equalization herein
Data are the transmission antenna data R of single channeltx_ant1；When transmitting terminal is two antenna, data are two-way after chip equalization herein
Transmission antenna data, be expressed as Rtx_ant1、Rtx_ant2。
Data be both used as the input of SCH interference removal process after the equilibrium, eliminated the SCH signal of reconstruct on this basis,
Input as CPICH channel descrambling and de-spreading step again.
CPICH channel is the important channel of WCDMA system, and the present invention carries out SCH using the symbol of CPICH channel and interferes phase
The estimation of relationship number, it is received it is balanced after chip data be converted to that CPICH symbol is descrambled, despreading is handled.
Specifically, being received according to chip-level of the spreading code of current service cell scrambling code ID and CPICH to two transmission antennas
Data carry out descrambling and de-spreading, wherein despreading descrambling uses well-known technique, obtain two antenna CPICH and receive symbol rCPICH_ant1、
rCPICH_ant2
Descrambling and de-spreading processing mainly is carried out to the CPICH symbol of two transmission antennas received above, obtained CPICH symbol
Number be used to calculate the related coefficients such as A1_cur, A2_cur, Acrs_cur described below.
Estimation sytem matrix experienced from transmitting terminal to signal after equalization is included in TSTD mode lower calculating one
Road cross-correlation item obtains SCH signal related coefficient A1_cur, A2_cur, Acrs_cur, and each CPICH symbol is to the primary knot of update
Described related coefficient A1_cur, A2_cur, Acrs_cur are carried out alpha filtering respectively and obtained by fruit for the stability of result
Sytem matrix A1, A2, Acrs.
If the channel response of Antenna1 and Antenna2 is expressed as h1、h2, equalization filtering coefficient is respectively e1、e2。
If P-SCH mode is cpsch, S-SCH mode is cpschIf req1For the SCH signal after 1 equilibrium of transmitting antenna, req2To emit day
SCH signal after 2 equilibrium of line.
When SCH is under TSTD mode, timesharing is sent on antenna 1 and antenna 2, when even timeslots,
Antenna 1 sends SCH, and when odd numbered slots, antenna 2 sends SCH.The discovery when carrying out interference and eliminating, only in even number
Gap and odd numbered slots are poor to antenna 1 and antenna 2 progress SCH elimination performance respectively, the study found that not transmitting
On the odd numbered slots of the antenna 1 of SCH and the even timeslots of antenna 2, there is also SCH；
The SCH received after then even timeslots Antenna1 and Antenna2 are balanced can be expressed as (by taking PSC as an example,
SSC is similarly):
req1=e1·h1·(cpsch+cssch)
req2=e2·h1·(cpsch+cssch)
The SCH received after 2 equilibrium of odd numbered slots antenna 1 and antenna can be expressed as,
req1=e1·h2·(cpsch+cssch)
req2=e2·h2·(cpsch+cssch)
In order to reconstruct the SCH signal r after two antenna equalisationseq1And req2To be carried out in the preceding 256chip of every time slot to SCH
Interference is eliminated, then needs to calculate e1·h1、e1·h2、e2·h1、e2·h2Equal SCH signal related coefficient.
But lack necessary condition due to directly seeking the above related coefficient, it is derived below how by CPICH symbol etc.
Effect obtains SCH signal related coefficient:
e2·h1、e1·h1、e2·h2It can be obtained by CPICH sign computation, if s0、s1Symbol is sent for CPICH, then
The CPICH of Antenna1 receives symbol after balanced, despreading, descrambling are as follows:
rCPICH_ant1(0)=e1·h1·s0+(-1)me1·h2·s0
rCPICH_ant1(1)=e1·h1·s1-(-1)me1·h2·s1
Antenna2CPICH receives symbol after balanced, despreading, descrambling are as follows:
rCPICH_ant2(0)=e2·h1·s0+(-1)me2·h2·s0
rCPICH_ant2(1)=e2·h1·s1-(-1)me2·h2·s1
Because CPICH emits symbol
Using the output CPICH symbol of antenna 1, can obtain
Using the output CPICH symbol of antenna 2, can obtain,
Also with the output CPICH symbol of antenna 2, can obtain
Wherein m indicates m-th of CPICH symbol pair in a radio frames, value range 0-74, the interior circulation of every frame.
According to result above, CPICH emits symbolObtain e1·h1、e2·h2、e2·h1,
Continuous item of the present invention by two transmitting antennas of reconstruct after the equalization, it is not necessary to estimate the power of P-SCH and S-SCH
And CPICH symbol of the estimation P-SCH to CPICH and S-SCH to each of CPICH power ratio, after directlying adopt equilibrium
The cross-correlation item between the auto-correlation item of antenna 1, the auto-correlation item and antenna 1 and antenna 2 of antenna 2 is estimated, so that TSTD mould
SCH interference is eliminated more accurate under formula, and storage and operand are smaller, improves system performance.
It will be proven below e1·h2And e2·h1It is associated, e1·h2、e2·h1The two need to only calculate one.
Had by above formula,
So only demand e2·h1, e can be obtained1·h2。
The present embodiment considers when only having an antenna to send SCH signal in two transmission antennas, due to the equilibrium system of two antennas
Number is different, and the data after two transmission antennas can be made balanced include that SCH signal needs to eliminate.The multiple antennas under TSTD mode
Between SCH continuous item generate during, only calculate cross-correlation item all the way and reduce operation, for reducing reconstruct SCH signal
Operand.
It calculates separately to obtain e using above formula1·h1、e2·h2、e2·h1, respectively A1_cur, A2_cur, Acrs_cur；
That is A1_cur=e1·h1、A2_cur=e2·h2、Acrs_cur=e2·h1；
The e1·h1、e2·h2、e2·h1Renewal frequency be each CPICH symbol pair, i.e. 512Chip update it is primary,
In order to increase the stability of estimated result, need to carry out alpha smothing filtering to result, wherein (0,1) α ∈
Enable A1_cur=e1·h1、A2_cur=e2·h2、Acrs_cur=e2·h1, for plural number, then obtain smoothed out estimated value
Are as follows:
A1=(1- α) A1+αA1_cur
A2=(1- α) A2+αA2_cur
Acrs=(1- α) Acrs+αAcrs_cur
It is described using SCH mode and the sytem matrix reconstruct TSTD mode under SCH signal and is eliminated be when
The preceding 256chip of gap, according to the SCH mode of step A and step E continuous item A1、A2、AcrsSCH interference is carried out to data after equilibrium
It eliminates.
In TSTD mode, interference is eliminated to be carried out in the preceding 256chip of the time slot, and is used according to odd even time slot difference
Different cancellations.
Specifically, being done in the following manner if current time slots are even timeslots in the preceding 256chip of current time slots
Disturb elimination:
yAnt1(i)=Rtx_ant1(i)-A1×cpsch(i)-A1×cssch(i), i=0 ..., 255
yAnt2(i)=Rtx_ant2(i)-Acrs×cpsch(i)-Acrs×cssch(i), i=0 ..., 255
If current time slots are odd numbered slots, interference elimination is carried out in the following manner in the preceding 256chip of the time slot:
yAnt1(i)=Rtx_ant1(i)-conj(Acrs)×cpsch(i)-conj(Acrs)×cssch(i), i=0 ...,
255
yAnt2(i)=Rtx_ant2(i)-A2×cpsch(i)-A2×cssch(i), i=0 ..., 255
To sum up, the present invention provides a kind of new SCH signal reconstruction removing method, pre- after ID by determining in cell searching
The method for depositing SCH mode reduces real-time operation amount；During the SCH continuous item under TSTD mode between multiple antennas generates,
It only calculates cross-correlation item all the way and reduces operation, for reducing the operand for reconstructing SCH signal.Further, the present invention provides
Whether the self-adaptive decision under TSTD mode carries out the scheme that SCH interference is eliminated, and avoids the occurrence of when power difference between two antennas
When big, the SCH of lower-powered antenna estimates inaccuracy, and elimination may play negative interaction instead, or when whole noise compares
Equally it is unsuitable for carrying out SCH interference elimination when low, there are negative interaction risks.
The present invention provides SCH interference blanking unit under a kind of TSTD mode, after mainly including the pre- storage of SCH mode, being balanced
Chip stream receiver, CPICH de-spread descrambler, SCH signal related coefficient calculator, SCH interference eliminator, and structural relation is as schemed
Shown in 3.
The pre- storage of SCH mode is used to determine in cell search process and the SCH mode of pre-stored service cell, packet
Include P-SCH mode and S-SCH mode；
It is recorded according to related data, SCH channel design is intended that the time slot for carrying out cell searching using P-SCH channel is same
Step carries out the identification of the frame synchronization and scrambling code group of cell searching using S-SCH channel.
All time slots of all cells of P-SCH channel are all made of identical P-SCH mode, and length 256 is referred to
The synchronous code generating process of 3GPP TS25.213 agreement 5.2.3 chapters and sections generates P-SCH mode and prestores, subsequent to use P-SCH mould
It is directly read when formula.
S-SCH channel uses 64 kinds of different S-SCH modes according to the difference of scrambling code group, in the frame synchronization of cell searching
S-SCH mode is generated in process and scrambling code group identification process, generating mode is referred to 3GPPTS25.213 agreement 5.2.3 chapters and sections
Synchronous code generating process, prestored in frame synchronization and during disturb code group identification by the S-SCH mode that this cell uses,
It is directly read when subsequent use S-SCH mode.
Particularly, after system changes scrambling code group in carrying out cell reselection process, new S-SCH mode is prestored again.
The present embodiment is by determining that the method for prestoring SCH mode after ID reduces real-time operation amount in cell searching.It is preferred that
Ground, the SCH mode of the serving cell prestored prestores mode using bit grades, so that the data volume prestored is smaller.
The present invention is that chip data after equilibrium are carried out with SCH interference to eliminate, and is relatively easy to implement in this way, after balanced at this time
Data are the superposition summation after all code channels spread spectrum, scrambling.Since remaining code channel is spread using different ovsf codes, between each other
Orthogonality be guaranteed, data after equilibrium are carried out with the symbol that corresponding transmission can be obtained after descrambling and de-spreading.And SCH channel exists
Transmitting terminal is not scrambled, is spread, and due to nonorthogonality, it influences the despreading of other code channel data descrambling serious, and the present invention is exactly
Using this feature, SCH channel is eliminated here.
Chip stream receiver is for receiving the output from chip equalization after the equilibrium, when transmitting terminal is single antenna,
Data are the transmission antenna data R of single channel after chip equalization hereintx_ant1；When transmitting terminal is two antenna, chip herein
Data are the transmission antenna data of two-way after equilibrium, are expressed as Rtx_ant1、Rtx_ant2。
Data be both used as the input of SCH interference eliminator after the equilibrium, eliminated the SCH signal of reconstruct on this basis, again
Input as CPICH despreading descrambler.
CPICH channel is the important channel of WCDMA system, and the present invention carries out SCH using the symbol of CPICH channel and interferes phase
The estimation of relationship number, it is received it is balanced after chip data be converted to that CPICH symbol is descrambled, despreading is handled.
The CPICH despreading descrambler is used to be sent according to the spreading code of current service cell scrambling code ID and CPICH to two
The chip-level of antenna receives data and carries out descrambling and de-spreading, wherein despreading descrambling uses well-known technique, obtains two antenna CPICH symbols
rCPICH_ant1、rCPICH_ant2；
Descrambling and de-spreading processing mainly is carried out to the CPICH symbol of two transmission antennas received above, obtained CPICH symbol
Number be used to calculate the related coefficients such as A1_cur, A2_cur, Acrs_cur described below.
The SCH signal related coefficient calculator be used for using the CPICH sign estimation from transmitting terminal to equilibrium after believe
Number sytem matrix experienced, comprising: A1_cur calculator, A2_cur calculator, Acrs_cur calculator and alpha filtering
Device, as shown in Figure 4；
The A1_cur calculator, A2_cur calculator, Acrs_cur calculator are respectively utilized to complete SCH signal phase relation
The calculating of number A1_cur, A2_cur, Acrs_cur, each CPICH symbol is to the primary result of update.
For the stability of result, the alpha filter distinguishes related coefficient A1_cur, A2_cur, Acrs_cur
It carries out alpha filtering and obtains sytem matrix A1, A2, the Acrs finally used.
If the channel response of Antenna1 and Antenna2 is expressed as h1、h2, equalization filtering coefficient is respectively e1、e2。
If P-SCH mode is cpsch, S-SCH mode is csschIf req1For the SCH signal after 1 equilibrium of transmitting antenna, req2To emit day
SCH signal after 2 equilibrium of line.
The SCH received after then even timeslots Antenna1 and Antenna2 are balanced can be expressed as (by taking PSC as an example,
SSC is similarly):
req1=e1·h1·(cpsch+cssch)
req2=e2·h1·(cpsch+cssch)
The SCH received after 2 equilibrium of odd numbered slots antenna 1 and antenna can be expressed as,
req1=e1·h2·(cpsch+cssch)
req2=e2·h2·(cpsch+cssch)
In order to reconstruct the SCH signal r after two antenna equalisationseq1And req2To be carried out in the preceding 256chip of every time slot to SCH
Interference is eliminated, then needs to calculate e1·h1、e1·h2、e2·h1、e2·h2Equal SCH signal related coefficient.
But lack necessary condition due to directly seeking the above related coefficient, it is derived below how by CPICH symbol etc.
Effect obtains SCH signal related coefficient:
e2·h1、e1·h1、e2·h2It can be obtained by CPICH sign computation, if s0、s1Symbol is sent for CPICH, then S
The CPICH of Antenna1 receives symbol after balanced, despreading, descrambling are as follows:
rCPICH_ant1(0)=e1·h1·s0+(-1)me1·h2·s0
rCPICH_ant1(1)=e1·h1·s1-(-1)me1·h2·s1
Antenna2CPICH receives symbol after balanced, despreading, descrambling are as follows:
rCPICH_ant2(0)=e2·h1·s0+(-1)me2·h2·s0
rCPICH_ant2(1)=e2·h1·s1-(-1)me2·h2·s1
Because CPICH emits symbol
Using the output CPICH symbol of antenna 1, can obtain
Using the output CPICH symbol of antenna 2, can obtain,
Also with the output CPICH symbol of antenna 2, can obtain
Wherein m indicates m-th of CPICH symbol pair in a radio frames, value range 0-74, the interior circulation of every frame.
According to result above, CPICH emits symbolObtain e1·h1、e2·h2、e2·h1,
Continuous item of the present invention by two transmitting antennas of reconstruct after the equalization, it is not necessary to estimate the power of P-SCH and S-SCH
And CPICH symbol of the estimation P-SCH to CPICH and S-SCH to each of CPICH power ratio, after directlying adopt equilibrium
The cross-correlation item between the auto-correlation item of antenna 1, the auto-correlation item and antenna 1 and antenna 2 of antenna 2 is estimated, so that TSTD mould
SCH interference is eliminated more accurate under formula, and storage and operand are smaller, improves system performance.
It will be proven below e1·h2And e2·h1It is associated, e1·h2、e2·h1The two need to only calculate one.
Had by above formula,
So only demand e2·h1, e can be obtained1·h2。
The present embodiment considers when only having an antenna to send SCH signal in two transmission antennas, due to the equilibrium system of two antennas
Number is different, and the data after two transmission antennas can be made balanced include that SCH signal needs to eliminate.The multiple antennas under TSTD mode
Between SCH continuous item generate during, only calculate cross-correlation item all the way and reduce operation, for reducing reconstruct SCH signal
Operand.
It calculates separately to obtain e using above formula1·h1、e2·h2、e2·h1, respectively A1_cur, A2_cur, Acrs_cur；
That is A1_cur=e1·h1、A2_cur=e2·h2、Acrs_cur=e2·h1；
The e1·h1、e2·h2、e2·h1Renewal frequency be each CPICH symbol pair, i.e. 512Chip update it is primary,
In order to increase the stability of estimated result, need to carry out alpha smothing filtering to result, wherein (0,1) α ∈
Enable A1_cur=e1·h1、A2_cur=e2·h2、Acrs_cur=e2·h1, for plural number, then obtain smoothed out estimated value
Are as follows:
A1=(1- α) A1+αA1_cur
A2=(1- α) A2+αA2_cur
Acrs=(1- α) Acrs+αAcrs_cur
SCH mode and CPICH the despreading descrambler that the SCH interference eliminator is prestored using the pre- storage of SCH mode are obtained
The sytem matrix obtained reconstructs the SCH signal under TSTD mode and is eliminated.
Specifically, in the preceding 256chip of time slot, the SCH mode prestored using the pre- storage of SCH mode and CPICH despreading solution
Disturb the device sytem matrix A obtained1、A2、AcrsSCH interference is carried out to data after equilibrium to eliminate.
Particularly, in TSTD mode, the interference of SCH interference eliminator is eliminated to be carried out in the preceding 256chip of current time slots,
And different cancellations is used according to odd even time slot difference.
Specifically, being done in the following manner if current time slots are even timeslots in the preceding 256chip of the time slot
Disturb elimination:
yAnt1(i)=Rtx_ant1(i)-A1×cpsch(i)-A1×cssch(i), i=0 ..., 255
yAnt2(i)=Rtx_ant2(i)-Acrs×cpsch(i)-Acrs×cssch(i), i=0 ..., 255
If current time slots are odd numbered slots, interference elimination is carried out in the following manner in the preceding 256chip of the time slot:
yAnt1(i)=Rtx_ant1(i)-conj(Acrs)×cpsch(i)-conj(Acrs)×cssch(i), i=0 ...,
255
yAnt2(i)=Rtx_ant2(i)-A2×cpsch(i)-A2×cssch(i), i=0 ..., 255
Further, whether the self-adaptive decision that the present invention provides under a kind of TSTD mode carries out the side that SCH interference is eliminated
Case, when power difference is big between two antennas, the SCH of lower-powered antenna estimates inaccuracy, and elimination may be played negative instead
Effect, or be equally unsuitable for carrying out SCH interference elimination when whole noise is relatively low, there are negative interaction risks.
Preferably as the achievable mode of another kind, as shown in figure 5, SCH interference blanking unit under TSTD mode of the present invention
Including SCH interfere eliminate controller, with it is balanced after chip stream receiver be connected, for according to historical channel estimated result obtain
The SNR estimated value of two transmission antennas determines whether that carrying out SCH interference eliminates according to the SNR estimated value.
It specifically includes:
302-1, the current channel impulse response che for receiving data is obtained first1、che2, wherein che1It indicates to send day
The channel estimation results of line 1, che2Indicate the channel estimation results of transmission antenna 2.
che1、che2Estimation can be obtained using general relevant way, estimation mode non-present invention protects content,
It repeats no more.
302-2, then according to the che of acquisition1、che2, Signal to Noise Ratio (SNR) _ est of two transmission antennas is estimated respectively1With
SNR_est2。
Specifically, with che1SNR estimation for, if che1The a length of L of window, then first search for the long range of L window in maximum
The power Max_pwr of diameter distinguishes signal diameter and noise path using the 1/N of Max_pwr as thresholding, accumulating signal diameter power P wr with make an uproar
Sound diameter power Noise obtains the signal-to-noise ratio (SNR) estimation value of the two
SNR_est=Pwr/Noise
The SNR estimated value SNR_est of two transmission antennas is obtained according to the above aspect1With SNR_est2。
302-2, the SNR estimated value SNR_est according to two transmission antennas1With SNR_est2Interference is judged whether to disappear
It removes:
If SNR_est1< SNR_Th, and SNR_est2< SNR_Th, then current time slots are interfered without SCH and are eliminated, and are directly moved back
Interference cancellation process out.
If the SNR estimated value SNR_est of two transmission antennas1With SNR_est2At least one is greater than SNR_Th, then after carrying out
Continuous SCH, which is interfered, to be eliminated.
The SNR_Th is channel quality thresholds, characterizes the fine or not degree of channel quality, different actual wireless channel rings
Border uses different values.
To sum up, the present invention provides a kind of new SCH signal reconstruction cancellation element, pre- after ID by determining in cell searching
The method for depositing SCH mode reduces real-time operation amount；During the SCH continuous item under TSTD mode between multiple antennas generates,
Only to reduce operation, (when single antenna, certain calculates cross-correlation item all the way to cross-correlation item, when two antennas, also only all the way for calculating
Calculate all the way), for reducing the operand of reconstruct SCH signal.Further, the present invention provides adaptively sentencing under TSTD mode
The scheme that SCH interference is eliminated certainly whether is carried out, is avoided the occurrence of when power difference is big between two antennas, lower-powered antenna
SCH estimation inaccuracy, elimination may play negative interaction instead, or equally be unsuitable for carrying out SCH when whole noise is relatively low
Interference is eliminated, and there are negative interaction risks.
The embodiment of the present invention has carried out further detailed description to the object, technical solutions and advantages of the present invention, is answered
Understand, above embodiments are only the preferred embodiment of the present invention, are not intended to limit the invention, all in the present invention
Spirit and principle within any modification, equivalent substitution, improvement and etc. made for the present invention, should be included in protection of the invention
Within the scope of.
Claims (8)
1. the synchronous channel SCH interference elimination method under a kind of time-switching transmitting diversity TSTD mode, it is characterised in that: obtain
CPICH Common Pilot Channel CPICH symbol after equilibrium, is undergone from transmitting terminal to signal after equalization using the CPICH sign estimation
Sytem matrix, using SCH mode and the sytem matrix reconstruct TSTD mode under SCH signal and eliminated；The SCH
Mode is the SCH mode for the serving cell for determining and prestoring in cell search process, including primary synchronization channel P-SCH mode
With auxiliary synchronization channel S-SCH mode.
2. the SCH interference elimination method under TSTD mode according to claim 1, it is characterised in that: when system is small in progress
After changing scrambling code group in area's reuse adoption process, new S-SCH mode is prestored again.
3. the SCH interference elimination method under TSTD mode according to claim 1, it is characterised in that: pre-stored service cell
SCH mode prestores mode using bit grades.
4. the SCH interference elimination method under TSTD mode according to claim 1, it is characterised in that: balanced in the acquisition
Before CPICH symbol afterwards, the Signal to Noise Ratio (SNR) estimated value including obtaining two transmission antennas according to historical channel estimated result, root
Determine whether that carrying out SCH interference eliminates according to the SNR estimated value.
5. the SCH interference elimination method under TSTD mode according to claim 1, it is characterised in that: after the acquisition is balanced
CPICH symbol, comprising: received on one or more stream it is balanced after chip signal, wherein including all reception signals
Chip signal after equilibrium；The despreading descrambling that CPICH channel is carried out to chip signal after received equilibrium, obtains CPICH symbol.
6. synchronous channel SCH interference blanking unit under a kind of time-switching transmitting diversity TSTD mode, it is characterised in that: include:
The pre- storage of SCH mode, for determining the SCH mode of simultaneously pre-stored service cell, including main synchronization in cell search process
Channel P-SCH mode and auxiliary synchronization channel S-SCH mode；
Chip stream receiver after equilibrium receives data for receiving chip-level, is the transmission of single channel when transmitting terminal is single antenna
Antenna data is the transmission antenna data of two-way when transmitting terminal is two antenna；
CPICH de-spread descrambler, for according to the spreading code of current service cell scrambling code ID and CPICH Common Pilot Channel CPICH to two
The chip-level of transmission antenna receives data and carries out descrambling and de-spreading, obtains two antenna CPICH symbols；
SCH signal related coefficient calculator, for being passed through from transmitting terminal to signal after equalization using two antenna CPICH sign estimations
The sytem matrix gone through；
What SCH interference eliminator, the SCH mode prestored using the pre- storage of SCH mode and SCH signal related coefficient calculator were obtained
Sytem matrix reconstructs the SCH signal under TSTD mode and is eliminated.
7. SCH interference blanking unit under TSTD mode according to claim 6, it is characterised in that: interfered including SCH and eliminate control
Device processed, with it is balanced after chip stream receiver be connected, for according to historical channel estimated result obtain two transmission antennas noise
Than SNR estimated value, determine whether that carrying out SCH interference eliminates according to the SNR estimated value.
8. SCH interference blanking unit under TSTD mode according to claim 6, it is characterised in that: SCH interference eliminator is done
It disturbs to eliminate and be carried out in the preceding 256chip of current time slots, and different cancellations is used according to odd even time slot difference.
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