CN1640041A - Implement method and apparatus for downlink synchronization subsystem - Google Patents
Implement method and apparatus for downlink synchronization subsystem Download PDFInfo
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- CN1640041A CN1640041A CN03805483.3A CN03805483A CN1640041A CN 1640041 A CN1640041 A CN 1640041A CN 03805483 A CN03805483 A CN 03805483A CN 1640041 A CN1640041 A CN 1640041A
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/69—Spread spectrum techniques
- H04B1/707—Spread spectrum techniques using direct sequence modulation
- H04B1/7073—Synchronisation aspects
- H04B1/70735—Code identification
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/69—Spread spectrum techniques
- H04B1/707—Spread spectrum techniques using direct sequence modulation
- H04B1/7073—Synchronisation aspects
- H04B1/7075—Synchronisation aspects with code phase acquisition
- H04B1/7077—Multi-step acquisition, e.g. multi-dwell, coarse-fine or validation
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/69—Spread spectrum techniques
- H04B1/707—Spread spectrum techniques using direct sequence modulation
- H04B1/7073—Synchronisation aspects
- H04B1/7083—Cell search, e.g. using a three-step approach
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B2201/00—Indexing scheme relating to details of transmission systems not covered by a single group of H04B3/00 - H04B13/00
- H04B2201/69—Orthogonal indexing scheme relating to spread spectrum techniques in general
- H04B2201/707—Orthogonal indexing scheme relating to spread spectrum techniques in general relating to direct sequence modulation
- H04B2201/70702—Intercell-related aspects
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Abstract
The present invention relates to an implement method and apparatus for downlink synchronization subsystem, which can detect the boundary of initial frame, and the initial frequency can be catched by using the result of initial frame boundary detection. Then, it can carry the cell search and selection, the multipath signal searching and tracing, the carrier frequency tracking, and timing frequency tracking, In CDMA system, by implementing the frequency catching, downlink synchronization acquisition and cell identification, providing multipath information of traffic channel, and running the carrier frequency tracking, the present invention can ensure the accuracy of timing frequency, and have the characteristic of simplicity and utility.
Description
A kind of downlink synchronization subsystem implementation method and engineering device technique field are the present invention relates to wireless communication technology field, and more particularly to CDMA systems are concretely a kind of downlink synchronization subsystem implementation method and device.Background technology
Current C draws A technologies and quickly grown, in the research process to the tdd mode of the cdma system using LAS codes（Such as：In the LinkAirll l TD- LAS experimental systems of Lianyu Communication Inc）, it can be deduced that：System design and the initial carrier frequency shift realized are less than normal value500Hz, now the LA polarity sequences of different districts can be accurately identified, and down-going synchronous physical channel can be de-spread on whole 874Tc, therefore using the wave filter for being matched with each cell downlink synchronization physical channels, down-going synchronous capture and cell identification can be just realized simultaneously, it is not necessary to carry out the adjustment of carrier frequency.In commercial LAS-CDMA TDD systems, the frequency accuracy of mobile station crystal oscillator is general in several ppm or so, is operated in 2GHz frequency ranges, carrier frequency offset is typically between Ι Κ Η ζ to Ι Ο Κ Η ζ.Under these conditions, the LA polarity sequences of different districts can not be accurately identified, and the despreading up to 874Tc can not be used, therefore, the implementation method and device that down-going synchronous capture and cell identification are realized in TD- LAS systems need to be found, and then obtains the implementation method and device for the universal effective down-going synchronous capture of general cdma system and cell identification.The content of the invention
It is an object of the invention to, a kind of downlink synchronization subsystem implementation method and device are provided, to realize frequency acquisition in a cdma system, down-going synchronous capture and cell identification are realized simultaneously, multi-path information is provided for the reception of Traffic Channel, and carry out the tracking of carrier frequency, it is ensured that timing frequency it is accurate, and with it is simple and practical the characteristics of.
The technical scheme is that：
A kind of downlink synchronization subsystem implementation method, it is characterised in that comprise the following steps：Initial frame boundary is detected；
The result detected using initial frame boundary, carries out original frequency capture；
Carry out cell searching and selection；
Carry out the search and tracking of multipath signal；
Carry out carrier frequency tracking；
It is timed frequency-tracking.
Described refers to initial frame boundary progress detection：In initial frame boundary detection, by extracting relevant peaks with the wave filter that all cell downlink synchronization physical channels are matched, frame boundary detection is realized；Because all cells use different bipolarity LA polarity sequences, so down-going synchronous matched filter can only carry out matched filtering on time slot, the incoherent merging of LA is carried out on whole down-going synchronous physical channel.
Described carry out original frequency capture refers to：After the completion of initial frame boundary detection, mobile station can be obtained by the starting timing position of one or more down-going synchronous physical channels that may be present from different districts；Movement station selects the boundary information of an an energy most strong cell, and carrier frequency offset is obtained using down-going synchronous physical channel, and need to adjust the VC0 of radio frequency, completes initial carrier frequency capture
Described carry out cell searching and selection refer to：All cell/sections with enough signal intensities are searched, and down-going synchronous is set up with selected cell.
The search and tracking of described progress multipath signal refer to：Multipath searching and tracking are to obtain frame synchronization, code synchronization and carrier synchronization in mobile station, and are determined after Target cell, and selecting suitable path in the reception signal for reaching mobile station by mulitpath, there is provided to RAKE receiver.
Described carry out carrier frequency tracking refers to：Initial frequency difference is reduced within 500Hz by initial carrier frequency capturing unit, cell identification unit obtains the LA+LS combinations used in this cell；Mobile station is tracked using descending CP continuous pilot channel working frequency, and residual frequency is reduced within 100Hz, meets demodulation needs.
The described frequency-tracking that is timed refers to：Timing frequency tracking is detected using mobile station
Frame period is compared with the accurate cycle, to extract clocking error.
Method of the present invention, it is characterised in that its step further comprises：
Initial frame boundary detection is carried out after mobile platform started first, if any down-going synchronous physical channel could not be detected, frame boundary detection will be carried out always；
After the completion of frame boundary detection, initial carrier frequency capture and cell searching and selection are carried out, until cell searching and chosen successfully, if the time of cell searching and selection is more than a certain parameter M, initial frame boundary detection is re-started；
Initial carrier frequency capture and cell searching and it is chosen successfully after, obtain the polarity sequence of serving cell, Cel l ID, and obtain the LS+LA Ma Group of the cell/section；
Multipath searching and tracking ring are started working, and send the multi-path information for receiving signal to upper strata, timing tracking ring and carrier tracking loop and BCH channels are received and can run, and carry out CRC check.
Device is realized present invention also offers a kind of downlink synchronization subsystem, it is characterised in that including：Initial frame boundary detection means, initial carrier frequency acquisition equipment, cell searching and selection device, Multipath searching and tracks of device, carrier frequency tracking device, timing frequency tracks of device；
Input signal enters described initial frame boundary detection means, detects after down-going synchronous physical channel, the information of initial frame boundary is sent into described initial carrier frequency acquisition equipment and described cell searching and selection device；
Described initial carrier frequency acquisition equipment and cell searching and selection device utilize the information of initial frame boundary and the reception signal of descending synchronous signal channel, carry out original carrier capture and cell searching selection, until cell searching and chosen successfully, the output signal of described initial carrier frequency acquisition equipment is original carrier frequency difference；Described cell searching and the output signal of selection device are the energy of each cell searched and reach delay, and these information are reported to upper strata；
Described multipath searching device and tracks of device are using frame due in and the reception signal of descending synchronous signal channel, and finding multi-path information is used for described timing frequency tracks of device and described carrier frequency tracking device.
Described initial frame boundary detection means includes：
Input：By the reception signal of baseband filter（4/c) ;
Output：The position of the initial frame boundary of the most strong cell of the energy of search, scope：(the original frequency acquisition equipment described in 0,30720*4 includes：
Input：Signal is received by the descending synchronous signal channel of baseband filter（4/c), the position of frame boundaries；
Output：Carrier frequency offset, scope：（- 5 z, 5KHz ).
Described cell searching and selection device includes： '
Input：Signal is received by the descending synchronous signal channel of baseband filter（4 c), the position of frame boundaries；
Output：The frame boundaries position of each cell and energy.
The search of described multipath signal and tracks of device include：
Input：Signal is received by the descending synchronous signal channel of baseband filter（4) the frame boundaries position of cell, is selected；
Output：The position in two footpaths；
Multipath searching and tracking are to obtain frame synchronization, code synchronization and carrier synchronization in mobile station, and are determined after Target cell, and selecting suitable path in the reception signal for reaching mobile station by mulitpath, there is provided to RAKE receiver.
The blunt track device of described carrier frequency includes：
Input：Signal is received by the downlink traffic channel of baseband filter（4/c), the position in two footpaths；Output：Carrier frequency offset（- 500Hz, 500Hz);
Initial frequency difference is reduced within 500Hz by initial carrier frequency capturing unit, cell identification unit obtains the LA+LS combinations used in this cell；Mobile station is tracked using descending CP continuous pilot channel working frequency, and residual frequency is reduced within 100Hz, meets demodulation needs.
The blunt track device of described timing frequency includes：
Input：The position in the first footpath；
Output：Timing frequency deviation（- 200Hz, 200Hz) ;
Timing frequency tracking is to be compared with the accurate cycle in the frame period detected using mobile station, to extract clocking error. .
Device of the present invention, it is characterised in that also include：Baseband filter, shunt, RF VC0, BB VCO, CRC check device；
After mobile platform started, baseband receiving signals are after 4fc baseband filters, into described initial frame boundary detection means, after detecting down-going synchronous physical channel, by the information feeding of initial frame boundary described initial carrier frequency acquisition equipment and cell searching and selection device, described initial carrier frequency acquisition equipment and cell searching and selection device utilize the information of initial frame boundary and the reception signal of descending synchronous signal channel, carry out original carrier capture and cell searching selection, until cell searching and chosen successfully, the output signal of described initial carrier frequency acquisition equipment is original carrier frequency difference, VC0 for adjusting radio frequency, described cell searching and the output signal of selection device are the energy of each cell searched and reach delay, these information are reported to upper strata, descending Multipath searching and tracks of device utilize frame due in and the reception signal of descending synchronous signal channel, finding multi-path information is used for described timing frequency tracks of device, the reception of described carrier frequency tracking device and BCH channels and described CRC calibration equipments, the output signal of described timing frequency tracks of device is used to adjust base band timing VC0;Described carrier frequency tracking device calculates carrier beat, the VC0 for adjusting radio frequency using multi-path information and the reception signal of descending CP continuous pilot channel.
The beneficial effects of the present invention are, by providing a kind of downlink synchronization subsystem implementation method and device, to realize the frequency acquisition in cdma system, down-going synchronous capture and cell identification are realized simultaneously, multi-path information is provided for the reception of Traffic Channel, and carry out the tracking of carrier frequency, it is ensured that timing frequency it is accurate, and with cylinder list it is practical the characteristics of.Wherein：
Initial frame boundary is detected：Detect the frame boundaries that there may be cell；
Original frequency is captured：The result detected using initial frame boundary, obtains the frame start position of down-going synchronous physical channel, carries out the Partly despread of LS codes, frequency acquisition is realized using fft algorithm, by carrier frequency offset from KHz range shorter to 500Hz below；
Cell searching and selection：When carrier frequency offset drops to below 500Hz, utilize LS+LA's
Matched filtering, down-going synchronous physical channel is de-spread on whole 874Tc, and down-going synchronous capture and cell identification can be realized simultaneously；
The search and tracking of multipath signal：After cell searching is with Dry is selected, movement station carries out the search and tracking of multipath signal using descending synchronous signal channel, and multi-path information is provided for the reception of Traffic Channel；
Carrier frequency tracking：Because the reception of Traffic Channel requires that the deviation of carrier frequency is less than 100Hz, it is therefore desirable to constantly carry out the tracking of carrier frequency, using CP continuous pilot channel, the tracking of carrier frequency is carried out using the method for Differential Detection, cylinder list is practical；
The blunt track of timing frequency：Movement station, which is used for base band timing and the VC0 of sampling and the VC0 of base station, an initial deviation, and deviation easily produces greatly slip, influences the quality of reception of Traffic Channel, it is therefore desirable to constantly adjust VC0 frequency, it is ensured that timing frequency it is accurate.
Brief description of the drawings
Fig. 1 is the subframe structure figure of descending synchronous signal channel；
Fig. 2 is the control flow chart of down-going synchronous subsystem；
Fig. 3 is the structured flowchart of down-going synchronous subsystem.The invention provides a kind of downlink synchronization subsystem implementation method and device for embodiment, including initial frame boundary detection, original carrier capture, cell searching and selection, the search of multipath signal and tracking, carrier track and timing tracking scheduling algorithm, its feasibility by simulating, verifying, for cdma system it is synchronous realize to provide refer to and foundation.Below by taking TD- LAS systems as an example, and with reference to accompanying drawing, describe the embodiment of the present invention in detail.
The down-going synchronous subsystem of TD-LAS systems will complete following task：
1) initial frame boundary is detected；
2) original carrier is captured；
3) cell searching and selection；
4) search and tracking of multipath signal；
5) carrier frequency tracking； 、
6) timing frequency is tracked.
The a set of solution for the down-going synchronous subsystem that the embodiment of the present invention is designed mainly for the physical layer specification of TD-LAS systems, including initial frame boundary detection, original carrier capture, cell searching and selection, the search of multipath signal and tracking, carrier track, timing frequency tracking etc..
In TD- US systems, the structure of descending synchronous signal channel is as shown in Figure 1；The algorithm of all cells uses identical LS spreading codes（Referring to table 1), different modulation symbol code characters come distinguishing cell.Sub-frame of downlink synchronization has 8 time slots, and each slot length is with reference to table2, each one length of slot transmission is 72Chips down-going synchronous pulse, and the S codes of C codes and 24chips comprising 24chips, centre retains 24chips protection band, and down-going synchronous pulse starts transmission in the starting of each time slot.LS codes for descending synchronous signal channel are complex codes, and corresponding spread spectrum conciliates overclass and is similar to QPSK, as shown in table 4.8 time slots of sub-frame of downlink synchronization can transmit 8 modulation symbols, the mutually orthogonal code sequence of 8 bipolaritys can be obtained altogether, such as every a line or each row of 8 x 8Wal sh matrixes, these yard of sequence is called LA polarity sequences in TD-LAS systems（Referring to table 3).8 orthogonal LA polarity sequences can support 8 cell/section Group nets；Support bigger networking scale, it may be considered that and the method such as CP continuous pilot cell Shi Do of other cell identifications are combined, and different cell/section clusters can also be made to use different LA protection intervals in addition, expand D-SYNPCH signal collection.The spreading code of the descending synchronous signal channel of table 1.（LS codes）（j = ^I )
Wherein：The subframe slot length of A=(+j+++-) ,=(- j -++ -), C=(- j ---+), D=descending synchronous signal channel of (_++ -) table 2.
LA time slots（TS,) 0 1 2 3 4 5 6 7
Length (Tc) 96 98 100 102 104 106 108 80
The LA polar codes of the descending synchronous signal channel of table 3.
The LA polar codes of the descending synchronous signal channel of table 4.
In systems, initial carrier frequency shift is less than 500Hz, now the LA polarity sequences of different districts can be accurately identified, and down-going synchronous physical channel can be de-spread on whole 874Tc, therefore using the wave filter for being matched with each cell downlink synchronization physical channels, down-going synchronous capture and cell identification can be just realized simultaneously, it is not necessary to carry out the adjustment of carrier frequency.But in commercial CDMA system, the frequency accuracy of mobile station crystal oscillator is general in several ppm or so, is operated in 2GHz frequency ranges, carrier frequency offset is typically between Ι Κ Η ζ to Ι Ο Κ Η ζ.Under these conditions, the LA polarity sequences of different districts can not be accurately identified, and can not use the despreading up to 874Tc, therefore, original carrier capture must be carried out before the algorithm that down-going synchronous capture and cell Shi Do are realized in TD- LAS systems, frequency deviation is less than 500Hz.The flow of down-going synchronous subsystem is listed below：
1) initial frame boundary is detected：Detect the hardwood border that there may be cell；
2) original frequency is captured：The result detected using initial frame boundary, obtains the frame start position of down-going synchronous physical channel, carries out the Partly despread of LS codes, frequency acquisition is realized using fft algorithm, by carrier frequency offset from KHz range shorter to 500Hz below；
3) cell searching and selection：When carrier frequency offset drops to below 500Hz, LS+LA is utilized
Matched filtering, down-going synchronous physical channel de-spread on whole 874Tc, and down-going synchronous capture and cell identification can be realized simultaneously；
4) search and tracking of multipath signal：After cell searching and selection, movement station carries out the search and tracking of multipath signal using descending synchronous signal channel, and multi-path information is provided for the reception of Traffic Channel；
5) carrier frequency tracking：Because the reception of Traffic Channel requires that the deviation of carrier frequency is less than 100Hz, it is therefore desirable to constantly carry out the tracking of carrier frequency, using CP continuous pilot channel, the tracking of carrier frequency is carried out using the method for Differential Detection, cylinder list is practical；
6) timing frequency is tracked：Movement station, which is used for base band timing and the VC0 of sampling and the VC0 of base station, an initial deviation, and deviation easily produces greatly slip, influences the quality of reception of Traffic Channel, it is therefore desirable to constantly adjust VC0 frequency, it is ensured that timing frequency it is accurate.
The control of down-going synchronous subsystem flow is as shown in Fig. 2.Initial frame boundary detection is carried out after mobile platform started first, if any down-going synchronous physical channel could not be detected, frame boundary detection will be carried out always.After the completion of frame boundary detection, initial carrier frequency capture and cell searching and selection are carried out, until cell searching and chosen successfully, if the time of cell searching and selection is more than a certain parameter M, initial frame boundary detection is re-started.Initial carrier frequency capture and cell searching and it is chosen successfully after, obtain the LA polarity sequences of serving cell, Cel l ID, and obtain the LS+LA code characters of the cell/section.Multipath searching and tracking ring are started working afterwards, send the multi-path information for receiving signal to upper strata, timing tracking ring and carrier tracking loop and BCH channels are received and can run, and carry out CRC check.
The structure of the receiver of down-going synchronous subsystem is as shown in Fig. 3.After mobile platform started, baseband receiving signals are after 4/c baseband filters, and into IFBD, (initial frame boundary is detected）Unit, after detecting down-going synchronous physical channel, the information of initial frame boundary is sent into initial carrier frequency capturing unit and cell searching and selecting unit, initial carrier frequency capturing unit and cell searching and selecting unit carry out original carrier capture and small using the information of initial frame boundary and the reception signal of descending synchronous signal channel
Area searching is selected, until cell searching and chosen successfully, the output signal of initial carrier frequency capturing unit is original carrier frequency difference, vco for adjusting radio frequency, the output signal of cell searching and selecting unit is the energy of each cell searched and reaches delay, these information are reported to upper room, descending Multipath searching and tracking cell utilize frame due in and the reception signal of descending synchronous signal channel, finding multi-path information is used for timing frequency tracking cell, the reception of carrier frequency tracking unit and BCH channels and CRC verification units, the output signal of timing frequency tracking cell is used to adjust base band timing VC0;Carrier frequency tracking unit calculates carrier beat, the VC0 for adjusting radio frequency using multi-path information and the reception signal of descending CP continuous pilot channel;The explanation of each point such as table 5 in the receiver structure of down-going synchronous subsystem, the input of each module and output explanation such as table 6.The explanation of each point in the receiver structure of the down-going synchronous subsystem of table 5.
The output and input specification module input and output of each module in the receiver structure of the down-going synchronous subsystem of table 6.
The reception signal (4/ of baseband filter is passed through on initial frame sideC) search the most strong cell of energy initial frame boundary circle detection position, scope：（0,30720*4) original carrier receives multi-channel signal carrier frequency deviation (_ 5KHz, 5KHz) capture (4 c), the position of frame boundaries by the descending synchronous signal channel of baseband filter
Cell searching receives frame boundaries position and energy and the selection (4/c) of signal each cell, the position of frame boundaries by the descending synchronous signal channel of baseband filter
Multipath searching receives the position in the footpath of signal two by the descending synchronous signal channel of baseband filter
With tracking (4/c), the frame boundaries position of cell is selected
Carrier frequency receives multi-channel signal carrier frequency deviation (_ 500Hz, 500Hz) tracking (4/c), the position in two footpaths by the downlink traffic channel of baseband filter
Position timing frequency deviation (- 200Hz, the 200Hz) tracking in the footpath of timing frequency first
In initial frame boundary detection algorithm, by extracting relevant peaks with the wave filter that all cell downlink synchronization physical channels are matched, frame boundary detection is realized.Because all cells use different joyous polarity LA polarity sequences, down-going synchronous matched filter can only carry out matched filtering on time slot, and the incoherent merging of LA is carried out on whole down-going synchronous physical channel.
As shown in figure 1, despreading length of the down-going synchronous physical channel on time slot is 72Tc, corresponding 3dB performances loss point is 8KHz, therefore the maximum frequency deviation of this algorithm tolerance is [- 8KHz, 8KHz].
After the completion of the detection of first step initial frame boundary, mobile station can be obtained by the starting timing position of one or more down-going synchronous physical channels that may be present from different districts.Movement station selects the boundary information of an an energy most strong cell, utilizes FFT algorithms to calculate the VC0 of carrier frequency offset, constantly adjustment radio frequency, completes initial carrier frequency capture.After the completion of this step, carrier frequency offset will be down to below 500Hz.
The signal used in algorithm de-spreads length for 48Tc, and estimation is frequency-doubled signal, therefore the frequency departure scope that the algorithm can be estimated is [- 5KHz, 5KHz].
The purpose of cell searching is to search the cell/section of all enough signal intensities, and sets up down-going synchronous with selected cell.In TD- LAS systems, the Traffic Channel of different districts spreads code character using different LS and different LA is spaced.Mobile station will correctly demodulate the signal of a certain cell/section, and set up communication, must just obtain the LS code characters and the spaced information of LA of this cell/section Traffic Channel.Therefore in cell searching, mobile station must search for all possible cell flag sequence in down-going synchronous physical channel（Cel l ID sequence), detect the cell/section of all enough signal intensities, LS code characters that purpose cell/section uses and the spaced letters of LA is further obtained to improve reliability, the matched filtering on whole descending synchronous signal channel 874chip is used in algorithm, therefore the frequency departure scope of algorithm requirement is [- 500Hz, 500Hz].
The premise for realizing carrier frequency tracking is that Timing Synchronization is had been set up between mobile station and base station, and carrier frequency offset is reduced to below 500Hz by initial downlink capturing carrier from maximum 6KHz.There are some carrier frequency tracking algorithms, including FFT, DMP-FED, DD (difference frequency at present
Rate is detected）.Due to having used descending CP continuous pilot channel in TD-LAS systems, therefore frequency-tracking can be realized using descending CP continuous pilot channel.
Initial frequency difference is reduced to by initial carrier frequency capturing unit5Within 00Hz, cell Shi Do units obtain the LA+LS combinations used in this cell.So residual frequency can be just reduced within 100Hz by mobile station using the tracking of descending CP continuous pilot channel working frequency, meet demodulation needs.
Multipath searching and tracking are to obtain frame synchronization, code synchronization and carrier synchronization in mobile station, and are determined after Target cell, and selecting suitable path in the reception signal for reaching mobile station by mulitpath, there is provided to RAKE receiver.
In mobile communication environment, emitter sends signal and reaches receiver by different paths.The often different random amplitude fading of the signal experience of paths and phase place, and different time delays.These signals are reached after receiver, because plural number is added, cause the decline of composite signal.The presence of signal on these paths is also random, is existed at some moment, and some moment disappear, and some moment are stronger than other path signals, and some moment may have stronger path signal.In cdma communication system, it is possible to use the RAKE receiver including multiple branches comes to anti-multipath fading.
RAKE receiver is to detect the stronger path of multiple signals using a search unit, distributes to each branch.Each branch is responsible for synchronous with a paths signal, and demodulates signal therein, and each routing information then is pressed into certain compatible rule merging.
Timing frequency tracking is to be compared with the accurate cycle in the frame period detected using mobile station, to extract clocking error.
The row signal frame period is set for T, in TD-LAS systems, T=30720TC.When mobile station is identical with the clock frequency of base station, then the frame period of moving table measuring is also T.When mobile station and the clock frequency difference of base station are 4, sampling rate will change, and the frame period of measurement can also change.If mechanical periodicity is l, then have, wherein f is accurate clock frequency.So, by detection, l can be obtained and be used for correcting sampling clock.
In TD- LAS systems, multipath searching unit detects that the corresponding D-SYNCH channels in each path are receiving the position of signal sample sequence using code matched filter.Because D- SYNCH are descending at each
Signal frame position is fixed, and when no clocking error, the position detected is also constant.So the change in location provided using multipath searching unit, can detect that clock changes, so as to calculate clock frequency difference.
Due to the random change of multipath channel, multipath searching unit should provide the footpath information reached at first all the time, and assume that correspondence ^ is same paths, otherwise can introduce error.Clock frequency tracking cell will also do the cumulative smooth of multiframe to the frequency difference calculated, to reduce the influence of multi-path location error.
The beneficial effects of the present invention are, by providing a kind of downlink synchronization subsystem implementation method and device, to realize frequency acquisition, down-going synchronous capture and cell identification are realized simultaneously, multi-path information is provided for the reception of Traffic Channel, and carry out the tracking of carrier frequency, it is ensured that timing frequency it is accurate, and with it is simple and practical the characteristics of.
The present invention is described by taking TD-LAS systems as an example for above embodiment, but present embodiment is used to limit the present invention absolutely not, because the invention is not restricted to TD- LAS systems, its general principle and technology and corresponding implementation method and device are effective for general cdma system.
Claims (1)
- Claim1. a kind of downlink synchronization subsystem implementation method, it is characterised in that comprise the following steps：Initial frame boundary is detected；The result detected using initial frame boundary, carries out original frequency capture；Carry out cell searching and selection；Carry out the search and tracking of multipath signal；Carry out carrier frequency tracking；It is timed frequency-tracking.2. according to the method described in claim 1, it is characterised in that described that initial frame boundary progress detection is referred to：In initial frame boundary detection, by extracting relevant peaks with the wave filter that all cell downlink synchronization physical channels are matched, frame boundary detection is realized；Because all cells use different bipolarity LA polarity sequences, so down-going synchronous matched filter can only carry out matched filtering on time slot, the incoherent merging of LA is carried out on whole down-going synchronous physical channel.3. according to the method described in claim 1, it is characterised in that described carry out original frequency capture refers to：After the completion of initial frame boundary detection, mobile station can be obtained by the starting timing position of one or more down-going synchronous physical channels that may be present from different districts；Movement station selects the boundary information of an an energy most strong cell, and carrier frequency offset is obtained using down-going synchronous physical channel, and need to adjust the VC0 of radio frequency, completes initial carrier frequency capture.4. according to the method described in claim 1, it is characterised in that described carry out cell searching and selection refer to：All cell/sections with enough signal intensities are searched, and down-going synchronous is set up with selected cell.5. according to the method described in claim 1, it is characterised in that the search and tracking of described progress multipath signal refer to：Multipath searching and tracking are to obtain frame synchronization, code synchronization and carrier synchronization in mobile station, and are determined after Target cell, and selecting suitable path in the reception signal for reaching mobile station by mulitpath, there is provided to RAKE receiver.6. according to the method described in claim 1, it is characterised in that described carry out carrier frequency tracking refers to：Initial frequency difference is reduced within 500Hz by initial carrier frequency capturing unit, cell Shi Do units obtain the LA+LS combinations used in this cell；Mobile station is tracked using descending CP continuous pilot channel working frequency, and residual frequency is reduced within 100Hz, meets demodulation needs.7. according to the method described in claim 1, it is characterised in that the described frequency-tracking that is timed refers to：Timing frequency tracking is to be compared with the accurate cycle in the frame period detected using mobile station, to extract clocking error.8. according to the method described in claim 1, it is characterised in that its step further comprises：Initial frame boundary detection is carried out after mobile platform started first, if any down-going synchronous physical channel could not be detected, frame boundary detection will be carried out always；After the completion of frame boundary detection, initial carrier frequency capture and cell searching and selection are carried out, until cell searching and chosen successfully, if the time of cell searching and selection is more than a certain parameter M, initial frame boundary detection is re-started；Initial carrier frequency capture and cell searching and it is chosen successfully after, obtain the LA polarity sequences of serving cell, Cel l ID, and obtain the LS+LA code characters of the cell/section；Multipath searching and tracking ring are started working, and send the multi-path information for receiving signal to upper strata, and ring and carrier tracking loop are tracked when determining and BCH channels are received and can run, and carries out CRC check.9. a kind of downlink synchronization subsystem realizes device, it is characterised in that including：Initial frame boundary detection means, initial carrier frequency acquisition equipment, cell searching and selection device, Multipath searching and tracks of device, carrier frequency tracking device, timing frequency tracks of device；Input signal enters described initial frame boundary detection means, detects after down-going synchronous physical channel, the information of initial frame boundary is sent into described initial carrier frequency acquisition equipment and described cell searching and selection device；Described initial carrier frequency acquisition equipment and cell searching and selection device utilize the information of initial frame boundary and the reception signal of descending synchronous signal channel, carry out original carrier capture and cell searching selection, until cell searching and chosen successfully, the output signal of described initial carrier frequency acquisition equipment is just Beginning carrier beat；Described cell searching and the output signal of selection device are the energy of each cell searched and reach delay, and these information are reported to upper strata；Described multipath searching device and tracks of device are using frame due in and the reception signal of descending synchronous signal channel, and finding multi-path information is used for described timing frequency tracks of device and described carrier frequency tracking device.10. the device according to claim 9, it is characterised in that described initial frame boundary detection means includes：Input：By the reception signal of baseband filter；Output：The position of the initial frame boundary of the most strong cell of the energy of search, scope： ( 0, 30720*411. the device according to claim 9, it is characterised in that described original frequency acquisition equipment includes：Input：Signal, the position of frame boundaries are received by the descending synchronous signal channel of baseband filter；Output：Carrier frequency offset, scope：（- 5KHz, 5KHz ).12. the device according to claim 9, it is characterised in that described cell searching and selection device includes：Input：Signal, the position of frame boundaries are received by the descending synchronous signal channel of baseband filter；Output：The frame boundaries position of each cell and energy.13. the device according to claim 9, it is characterised in that the search of described multipath signal and tracks of device include：Input：Signal is received by the descending synchronous signal channel of baseband filter, the frame boundaries position of cell is selected；Output：The position in two footpaths；Multipath searching and tracking are to obtain frame synchronization, code synchronization and carrier synchronization in mobile station, and are determined after Target cell, and selecting suitable path in the reception signal for reaching mobile station by mulitpath, there is provided to RAKE receiver.14. the blunt device according to described in claim 9 of, it is characterised in that described carrier frequency tracking Device includes：Input：Signal, the position in two footpaths are received by the downlink traffic channel of baseband filter；Output：Carrier frequency offset（-500Hz, 500Hz) ;Initial frequency difference is reduced within 500Hz by initial carrier frequency capturing unit, cell identification unit obtains the LA+LS combinations used in this cell；Mobile station is tracked using descending CP continuous pilot channel working frequency, and residual frequency is reduced within 100Hz, meets demodulation needs.15. device according to claim 9, it is characterised in that described timing frequency tracks of device includes：Input：The position in the first footpath；Output：Timing frequency deviation（-200Hz, 200Hz) ;Timing frequency tracking is to be compared with the accurate cycle in the frame period detected using mobile station, to extract clocking error.16. the device according to claim 9, it is characterised in that also include：Baseband filter, shunt, RF VCO, BB VCO, CRC check device；After mobile platform started, baseband receiving signals are after 4 baseband filters, into described initial frame boundary detection means, detect after down-going synchronous physical channel, the information of initial frame boundary is sent into described initial carrier frequency acquisition equipment and cell searching and selection device；Described initial carrier frequency acquisition equipment and cell searching and selection device utilize the information of initial frame boundary and the reception signal of descending synchronous signal channel, carry out original carrier capture and cell searching selection, until cell searching and chosen successfully, the output signal of described initial carrier frequency acquisition equipment is original carrier frequency difference, the VC0 for adjusting radio frequency;Described cell searching and the output signal of selection device are the energy of each cell searched and reach delay, these information are blunt to accuse to upper strata, descending Multipath searching and tracks of device are using frame due in and the reception signal of descending synchronous signal channel, and finding multi-path information is used for described timing frequency tracks of device, the reception of described carrier frequency tracking device and BCH channels and described CRC check device；The output signal of described timing frequency tracks of device is used to adjust base band timing VC0; Described carrier frequency tracking device calculates carrier beat, the vco for adjusting radio frequency using multi-path information and the reception signal of descending CP continuous pilot channel.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| PCT/CN2003/000061 WO2004066532A1 (en) | 2003-01-23 | 2003-01-23 | Implement method and apparatus for downlink synchronization subsystem |
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| Publication Number | Publication Date |
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| CN1640041A true CN1640041A (en) | 2005-07-13 |
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ID=32739358
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN03805483.3A Pending CN1640041A (en) | 2003-01-23 | 2003-01-23 | Implement method and apparatus for downlink synchronization subsystem |
Country Status (3)
| Country | Link |
|---|---|
| CN (1) | CN1640041A (en) |
| AU (1) | AU2003211659A1 (en) |
| WO (1) | WO2004066532A1 (en) |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6005854A (en) * | 1997-08-08 | 1999-12-21 | Cwill Telecommunication, Inc. | Synchronous wireless access protocol method and apparatus |
| CN1047047C (en) * | 1997-10-05 | 1999-12-01 | 北京信威通信技术有限公司 | Method for establishing and holding synchronous code division multiple access communication chain |
| CN1131653C (en) * | 2000-03-27 | 2003-12-17 | 信息产业部电信科学技术研究院 | Small-region initial search method for CDMA digital mobile communication system |
| CN1174559C (en) * | 2000-06-05 | 2004-11-03 | 连宇通信有限公司 | Framing method are synchronous wireless system therewith |
| WO2002011317A1 (en) * | 2000-06-20 | 2002-02-07 | Linkair Communications, Inc. | A tdd framing method for physical layer of a wireless system |
| JP3729329B2 (en) * | 2000-09-19 | 2005-12-21 | 株式会社エヌ・ティ・ティ・ドコモ | Cell search method for mobile station in mobile communication system and mobile station in mobile communication system |
-
2003
- 2003-01-23 AU AU2003211659A patent/AU2003211659A1/en not_active Abandoned
- 2003-01-23 CN CN03805483.3A patent/CN1640041A/en active Pending
- 2003-01-23 WO PCT/CN2003/000061 patent/WO2004066532A1/en not_active Application Discontinuation
Also Published As
| Publication number | Publication date |
|---|---|
| AU2003211659A1 (en) | 2004-08-13 |
| WO2004066532A8 (en) | 2004-09-30 |
| WO2004066532A1 (en) | 2004-08-05 |
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