CN102026397A  Data demodulation method and equipment for physical random access channel  Google Patents
Data demodulation method and equipment for physical random access channel Download PDFInfo
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 CN102026397A CN102026397A CN2009100927153A CN200910092715A CN102026397A CN 102026397 A CN102026397 A CN 102026397A CN 2009100927153 A CN2009100927153 A CN 2009100927153A CN 200910092715 A CN200910092715 A CN 200910092715A CN 102026397 A CN102026397 A CN 102026397A
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Abstract
Description
Technical field
The present invention relates to mobile communication technology, data demodulation method and equipment on particularly a kind of Physical Random Access Channel.
Background technology
SD (Synchronization Detection, synchronous detecting) algorithm is used for the foundation of uplink synchronous process, is that the physical layer base band signal process of random access procedure realizes part.By realizing that uplink synchronous detects, can finish the connection between UE (User Equipment, subscriber equipment) and the eNodeB (evolution base station), thereby the uplink resource allocation that makes UE obtain eNodeB is prepared for normal transmitting uplink data also.
Fig. 1 is that LTE (Long Term Evolution, Long Term Evolution) uplink random inserts the input block diagram, provides PRACH (Physical Random Access Channel, the Physical Random Access Channel) position of demodulation part in whole SD subsystem among the figure.
The basic principle of PRACH demodulation is time domain sequences to be carried out DFT (Discrete FourierTransform, discrete Fourier transform (DFT)) conversion obtain frequency domain sequence, and algorithm complex depends primarily on counting of DFT conversion.Because the PRACH channel distortion experienced is spaced apart 1/12 or 1/2 of common subcarrier spacing, FFT (Fast Fourier Transform, fast fourier transform) the conversion corresponding data FFT points N that is of counting then _{Fft}12 times.For example: it is 24576 that the FFT conversion of Preamble under the 20M bandwidth (targeting sequencing) form 0 correspondence is counted.Therefore, a problem of systems face is: if directly carry out 24576 DFT conversion, complexity can be very high.
In fact PRACH only takies 6 PRB (physical resource block of full range band, Physical Resource Block), the full range band is done obviously relatively waste of DFT, therefore general way is to adopt filter that the frequencyregion signal of PRACH is leached earlier, and then it is downsampled, so just can reduce counting of DFT conversion, thereby reduce the algorithm implementation complexity.
Provide two kinds of PRACH demodulating algorithms at the different DFT conversion prior art of counting, a kind of is the DFT conversion scheme, and another kind is the timedomain filtering scheme.Wherein, the DFT conversion scheme is more directly perceived, when having N PRACH frequency domain channel in the subframe, only can obtain all PRACH frequencyregion signals by a DFT conversion.Therefore, this scheme mainly is applicable to the DFT less situation of counting, and conversion is counted when big for DFT, and implementation complexity is very high; The DFT conversion that needs is counted less, and minimum 1024 just can satisfy the demands after the filtering.Therefore, the filter scheme mainly is applicable to the DFT conversion bigger situation of counting.
Generally speaking, counting of the DFT conversion of PRACH is all bigger, and is not 2 integral number power, promptly can not directly adopt general FFT conversion.Be that example illustrates technical problem mainly below with the DFT of 0,24576 of preamble form.The Direct Transform method can be decomposed into 4 with 24576 ^{6}* 2*3, promptly the FFT by 6 bases 4, a base 2 and a base 3 realizes.This method computation complexity is bigger, and the memory cell that takies is many.
Timedomain filtering method is according to PRACH frequency domain distribution characteristics, adds downsampled method by the filter that is easy to realize and realizes.This scheme implementation procedure more complicated, and certain performance loss is arranged.Whether satisfy the system design needs, also need further assessment.
In sum, the deficiencies in the prior art are: directly DFT processing scheme algorithm is intuitively simple, but implementation complexity is too high, needs a large amount of addition and multiplying, also needs more memory cell.
FIR (finite impulse response) filtering algorithm can reasonable filtering PRACH channel outer interference, computing by downsampled minimizing FFT is counted, thereby simplify the computation complexity of DFT greatly, but, the filter of highorder still needs a large amount of multipliers or adder, and signal delay is bigger.In addition, the characteristic of filter and number of taps and tap coefficient all have relation, are difficult to the configuring condition flexible configuration according to PRACH.
Summary of the invention
The invention provides data demodulation method and equipment on a kind of PRACH, need to adopt a large amount of multiplier or adder because of the filter that uses highorder in order to separate timing at PRACH in the solution prior art, and the bigger problem of signal delay.
Data demodulation method on a kind of PRACH is provided in the embodiment of the invention, has comprised the steps:
The PRACH data spectrum that receives is adjusted to the zerofrequency both sides;
Suppress the outer interference of PRACH channel;
Adopt sample one time at every M sampling point;
N sampled point carried out fast fourier transform FFT, and M, N satisfy M*N=24576 or 4096;
Extract or 139 points the frequencyregion signal of the sampled point of the N behind FFT at 839.
Data demodulates on a kind of PRACH equipment is provided in the embodiment of the invention, has comprised:
Frequency regulation block is used for the PRACH data spectrum that receives is adjusted to the zerofrequency both sides;
Filter module is used to suppress the outer interference of PRACH channel;
Downsampled module is used for adopting sample one time at every M sampling point;
N point FFT module is used for N sampled point carried out FFT, and M, N satisfy M*N=24576 or 4096;
839/139 extraction module, the frequencyregion signal that is used for N sampled point behind the FFT extracts or 139 points at 839.
Beneficial effect of the present invention is as follows:
During the demodulation of the data of technical scheme provided by the invention on PRACH is implemented, the PRACH frequency that receives is adjusted near the zerofrequency; Suppress the outer interference of PRACH channel then; Adopt sample one time at every M sampling point; N sampled point carried out FFT; Extract or 139 points at last the frequencyregion signal of the sampled point of the N behind FFT at 839.
In technical scheme provided by the invention, utilize the PRACH channel only to take the characteristics of one section bandwidth, the PRACH frequency that receives is adjusted near the zerofrequency, and then suppressed the outer interference of PRACH channel; Therefore can utilize the lower filter of complexity to carry out filtering, further can utilize general FFT operation to finish the demodulation of PRACH again, owing to can adopt the lowerorder filter to realize demodulation, therefore the filter that has overcome highorder needs a large amount of multiplier or adder, and the bigger deficiency of signal delay.
Description of drawings
Fig. 1 is that the LTE uplink random inserts the input block diagram in the background technology;
Fig. 2 is the data demodulation method implementing procedure schematic diagram on the PRACH in the embodiment of the invention;
Fig. 3 is the general solution block diagram of PRACH demodulation DFT shortcut calculation in the embodiment of the invention;
Fig. 4 is the amplitudeversusfrequency curve schematic diagram of 127 rank FIR filters in the embodiment of the invention;
Fig. 5 is CIC filtering method fundamental block diagram signal in the embodiment of the invention;
Fig. 6 is 2 rank cic filter structural representations in the embodiment of the invention;
Fig. 7 moves the distribution schematic diagram of back 3 PRACH at frequency domain for embodiment of the invention intermediate frequency spectrum;
Fig. 8 is 2 rank cic filter amplitudefrequency characteristic schematic diagrames of 6 times of extractions in the embodiment of the invention;
Fig. 9 is the interior enlarged diagrams of 2 rank cic filter amplitudefrequency characteristic bands of 6 times of extractions in the embodiment of the invention;
Figure 10 is 3 PRACH detection block figure signals simultaneously in the embodiment of the invention;
Figure 11 is a PRACH demodulation pretreatment method implementing procedure schematic diagram in the embodiment of the invention;
Figure 12 is the data demodulates device structure schematic diagram on the PRACH in the embodiment of the invention.
Embodiment
Below in conjunction with accompanying drawing the specific embodiment of the present invention is described.
Fig. 2 is the data demodulation method implementing procedure schematic diagram on the PRACH, and as shown in the figure, separating timing at PRACH can comprise the steps:
Step 201, the PRACH data spectrum that receives is adjusted to the zerofrequency both sides;
Step 202, the outer interference of inhibition PRACH channel;
Step 203, adopt sample one time at every M sampling point;
Step 204, N sampled point carried out FFT;
Wherein,, M, N satisfy M*N=24576 or 4096.
Extract 839 or 139 points the frequencyregion signal of step 205, the sampled point of the N behind FFT.
In the technical scheme provided by the invention, basic thought is that the employing filter is handled, and, at first carries out frequency spectrum shift that is, then by low pass filter, does downsampledly again, finishes the proposition of N point FFT and 839 or 139 point data at last.If when having N PRACH channel in the subframe, only need carry out corresponding N time similar operation and get final product.Fig. 3 is the signal of DFT shortcut calculation block diagram, as shown in the figure, comprised in basic implementation procedure: what step 201 was performed is the frequency adjustment, what step 202 was performed is to suppress the outer interference of PRACH channel, adopted filter to realize in this step, what illustrate among the figure also is filter, and what step 203 was performed is downsampled, that step 204 is performed is N point FFT, and step 205 is performed is 839 or 139 extractions.
In the enforcement, for 839 or 139 extraction for, PRACH has 5 kinds of forms at present, wherein: Format4 is that TDD (Time Division Duplex, time division duplex) is peculiar.The technical scheme that the embodiment of the invention provides not only goes for wherein 4 kinds of forms of Format0～3 (i.e. 24576 inputs, 839 extractions), equally also be applicable to the 5th kind of form Format4 (4096 inputs, 139 extractions), and complexity is lower when implementing under Format4.
To be that example describes with Format0～3 mainly in the embodiment of the invention, those skilled in the art also can apply to Format4 with the execution mode under Format0～3 as required.
Fig. 3 provides the general solution block diagram of PRACH demodulation DFT shortcut calculation.Again mainly with 24576 points, double below with the main contents of 4096 DFT for example introduction enforcement.
In step 201 the PRACH frequency that receives is adjusted near the zerofrequency, the effect of this step is that the filter of being convenient to the back uses simple low pass filter commonly used to realize.
In step 202, suppress the interference outside the PRACH channel, downsampled the aliasing that noise and PUSCH (Physical Uplink Shared Channel, physical uplink link sharing channel) bring do not take place in order to what guarantee 24576 PRACH.
Accordingly, if then be that the spectral aliasing that noise and PUSCH bring does not take place for guarantee 4096 PRACH downsampled when extracting at 139.
Adopt M doubly to extract in step 203, promptly every M sampling point adopted once.The value of M is relevant with reduction procedure, generally in form Format0～3 is: 3,6,12 or 24.
Accordingly, be 1,2,4,8 or 16 in Format4.
In step 204, can adopt general FFT method to obtain.Wherein, for the value of N, in Format0～3 can for: 8192,4096,2048 or 1024.
Accordingly, in form Format4, can be 4096,2048,1024,512 or 256.
839 points in the middle of in step 205, from the frequencyregion signal that N is ordered, extracting.
Accordingly, then be to extract 139 points in form Format4.
In above each step implementation process, can adopt filter, traditional solution is to adopt the FIR filter of a highorder, the interference (other up channel and noise) that filtering PRACH channel is outer, doubly downsampled through M, by the FFT that 24576/M is ordered, extract at last and obtain 839 preamble frequency domain data again.The FFT with the back of choosing of M value here and FIR filter counts relation is arranged.
And in implementation process of the present invention, the band that bandwidth that occupies according to PRACH and needs suppress disturbs outward, can be easy to design the filter of satisfying the demand.Here can consider to adopt practical and convenient FIR filter, use 127 rank taps.Fig. 4 is the amplitudeversusfrequency curve schematic diagram of 127 rank FIR filters, when selecting the FIR filter for use, just can draw with reference to this figure in the enforcement.Magnitude Response is an amplitudefrequency response among the figure.
Further, in the implementation process, because the FIR filter order that adopts is than higher, the complexity of realization is than higher, it is also conceivable that the filter that adopts another kind of simple possible: cic filter (the cascade integrator comb filter, or be called the Hogenauer filter).
Then, in the invention process process, can adopt cic filter to finish filtering and downsampled process simultaneously in conjunction with downsampled process.That is, can adopt cic filter to suppress the outer interference of PRACH channel, and adopt sample one time at every M sampling point.Fig. 5 is the signal of CIC filtering method fundamental block diagram, as shown in the figure, compares with Fig. 2, having merged filtering and downsampled process, mainly is to do lowpass filtering with cic filter in the enforcement, does simultaneously doubly downsampled of M as required, do the FFT computing again, extract preamble at last.
Further, can handle a plurality of PRACH channels simultaneously according to the characteristics that are continuous distribution to a plurality of PRACH channels in the agreement 36.211 in the implementation process on frequency domain, thereby save computing cycle and resource.That is, be one group with 1 to 3 PRACH, the PRACH frequency that receives is adjusted near the zerofrequency simultaneously; Suppress the outer interference of PRACH channel simultaneously; Simultaneously adopt sample one time at every M sampling point; Simultaneously N sampled point carried out FFT; Extract or 139 points simultaneously the frequencyregion signal of the sampled point of the N behind FFT at 839.Introduce the concrete enforcement of this mode below.
Because partly the lowpass filtering scheme with general is close for frequency adjustment, N point FFT and 839 extractions, thus mainly introduce the enforcement of CIC filtering extraction here, and then set forth total solution.
Cic filter is derived from recursion rolling sum filter.Its amplitudefrequency response envelope is sin (x)/x type, so cic filter generally is to be placed on before or after the high performance linear phase low pass tapped delay line FIR filter, wherein the FIR filter is the passband that is used to compensate the cic filter injustice.CIC has very high computational efficiency as narrowband lowpass filter, thereby hardware normal and extraction and interpolation links together in Modern Communication System.
Fig. 6 is 2 rank cic filter structural representations, and wherein R represents the multiple that extracts.As seen from the figure, this cic filter combines filtering and abstraction module, finishes filtering and downsampled process jointly, and its filtering characteristic can be selected this two parameters according to the design needs fully by filtering exponent number and extracting multiple R decision.
Be it can also be seen that by Fig. 6 the cic filter implementation complexity is very low, without any need for multiply operation and a large amount of storages, processing delay is also very little, is fit to very much hardware system and realizes.
About the problem that unit negative feedback meeting the causing register on every grade of integrator of cic filter overflows, can consider that the complement code algorithm with 2 solves.As long as the word length of integrator can be held the maximum difference between any two adjacent sampled values, utilization has by periodically reel 2 complementary binary form of character of mould, and the comb filter of following later can calculate the correct difference between the adjacent integrator output sample.
In the LTE system, need to consider to detect at most 6 PRACH, general way is to do 6 times similarly to calculate or 6 tunnel parallel processings, but such processing can increase the time of system handles or need more hardware resource.
To Study on standards as can be known, being sent on the frequency domain of PRACH is partial continuous.For example send 6 PRACH, 3 PRACH send on one section continuous PRB, and in addition three PRACH send on the continuous PRB of another section.Therefore, can be divided into two groups to 6 PRACH in concrete the enforcement, detect PRACH according to following processing procedure then.
Fig. 7 is that 3 PRACH are that frequency adjustment (frequency spectrum shift) is done at the center at the distribution schematic diagram of frequency domain with in the middle of three PRACH that behind the frequency spectrum shift, that is, and and with the centre of frequency spectrum shift to simultaneously treated PRACH bandwidth.Frequency spectrum after moving is then shown in 7.
Fig. 8 is 2 rank cic filter amplitudefrequency characteristic schematic diagrames of 6 times of extractions, and Fig. 9 is the interior enlarged diagrams of 2 rank cic filter amplitudefrequency characteristic bands of 6 times of extractions.
Interference beyond three PRACH of filter filtering behind the frequency spectrum shift, basic scheme can be: do 6 times of extractions simultaneously with 2 rank cic filter filtering, obtain 4096 sampling points.That is, be one group with 1 to 3 PRACH, when every M sampling point is adopted a sample, can do 6 times of extractions simultaneously simultaneously with 2 rank cic filter filtering, obtain 4096 sampling points.Fig. 8 has provided 6 times of amplitudeversusfrequency curves that extract cic filter.
Fig. 9 has amplified the interior part of band of Fig. 8, and as seen from the figure, for 1.5 PRACH bandwidth 864*1.5*1.25kHz=1.62MHz, maximum attenuation is 3dB in the band.
Figure 10 is 3 PRACH detection block figure signals simultaneously, as shown in the figure, is 4096 FFT after the filtering, chooses the data of three PRACH correspondences respectively and carries out the PRACH detection.
Generally speaking, inserting detection system at random is not very high to the requirement of PRACH demodulation part, and the 3dB decay can't influence last detection performance in the CIC band.If but wish to weaken in the band decline to Effect on Performance, the FIR filter of the low order of can behind cic filter, connect make export narrowed width and passband gain smooth.The Frequency and Amplitude response ideal situation of this compensation FIR filter should be the contrary of cic filter passband response.That is, the FIR filter of series connection low order behind cic filter is used so that output narrowed width and passband gain are smooth.Further, the response of the Frequency and Amplitude of the FIR filter of low order can be the contrary of cic filter passband response.
Provide the coefficient of the compensation FIR filter of three rank, 15 taps below:
[1，4，16，32，64，136，352，1312，352，136，64，32，16，4，1]/790
Further, can also comprise in the enforcement:
Before inserting detection at random, physical layer obtains the information of PRACH configuration information and uplinkdownlink configuration from high level;
Information acquisition preamble sign indicating number timefrequency mapping according to PRACH configuration information and uplinkdownlink configuration;
Determine to handle number, frequency translation position, M, N one of them or its combination of PRACH according to preamble sign indicating number timefrequency mapping.
In concrete the enforcement, before physical layer inserts detection at random, obtain the information of PRACH configuration and uplinkdownlink configuration, can obtain preamble sign indicating number timefrequency by tabling lookup and to insert situation from high level.Like this, in the PRACH demodulation process, just can select different processing modes and parameter as the case may be, comprise: handle several PRACH, frequency translation position, downsampled multiple M, FFT points N etc.
Figure 11 is a PRACH demodulation pretreatment method implementing procedure schematic diagram, as shown in the figure, can comprise the steps:
Step 1101, read high layer information, obtain the mapping of preamble video;
Step 1102, definite PRACH number and each demodulation parameter handled;
Step 1103, frequency spectrum shift, CIC filtering extraction, N point FFT and preamble extract
In the enforcement, determine that the PRACH number is meant according to the preamble timefrequency mapping that obtains and to know the current PRACH number that may insert and time domain and frequency domain position, can select thus with one tunnel still twoway PRACH processing, and handle several PRACH simultaneously.For example, obtaining the PRACH configuration index from high level is 18, UL/DL (up/descending) configuration index is 5, then can know currently have 6 PRACH and insert simultaneously by 3GPP TS 36.211 table 5.7.14, therefore the PRACH processing scheme selects twoway PRACH to handle, and 3 PRACH are handled on each road simultaneously, frequency spectrum shift is the center with the PRACH of centre, calculate the frequency spectrum shift point, the extracting multiple M of cic filter selects 6 simultaneously, and the FFT points N selects the preamble sign indicating number of 4096 and 3 PRACH channels to extract simultaneously.
Above arrangements is flexible, and can be according to different selection of configuration different processing units and suitable parameter can maximally utilise hardware resource like this, reduce unnecessary power consumption.For example, if known may have a PRACH to insert at first field simultaneously, that just need not handle PRACH at second field again, in addition, also only need one the tunnel to handle when handling PRACH, and do not enable another road work, simultaneously, cic filter extracting multiple M can select 12 or 24, and corresponding FFT points N selects 2048 or 1024.Such processing is simple, and very beneficial to the reduction of system power dissipation, and simple CIC filters solutions has guaranteed the possibility of such flexible configuration.
Based on same inventive concept, a kind of PRACH demodulated equipment also is provided in the embodiment of the invention, because the principle that this equipment is dealt with problems is similar to the PRACH demodulation method, so the enforcement of this equipment can repeat part and repeat no more referring to the enforcement of method.
Figure 12 is a PRACH demodulated equipment structural representation, as shown in the figure, can comprise in the demodulated equipment:
Frequency regulation block 1201 is used for the PRACH data spectrum that receives is adjusted to the zerofrequency both sides;
Filter module 1202 is used to suppress the outer interference of PRACH channel;
Downsampled module 1203 is used for adopting sample one time at every M sampling point;
N point FFT module 1204 is used for N sampled point carried out FFT, and M, N satisfy M*N=24576 or 4096;
839/139 extraction module 1205, the frequencyregion signal that is used for N sampled point behind the FFT extracts or 139 points at 839.
In the enforcement, at first frequency regulation block is carried out frequency spectrum shift, then by having adopted the filter module filtering of low pass filter, do downsampledly again through downsampled module, finish N point FFT and at 839 by N point FFT module, 839/139 extraction module at last or 139 point data propose.If when having N PRACH channel in the subframe, only need carry out N similar operation and get final product.
With 24576 points, 4096 DFT is example, and demodulated equipment can be in the enforcement:
Frequency regulation block is adjusted to the PRACH frequency that receives near the zerofrequency, and the filter module of being convenient to the back can use simple low pass filter commonly used to realize.
Filter module suppresses the outer interference of PRACH channel, and what guarantee 24576 points or guarantee 4096 PRACH when extracting at 839 when extracting at 139 downsampled the aliasing that noise and PUSCH bring does not take place.
Downsampled module adopts M doubly to extract, and promptly every M sampling point adopted once.The value of M is relevant with reduction procedure, and general M in Format0～3 is: 3,6,12 or 24, and be 1,2,4,8 or 16 in form Format4.
N point FFT module can adopt general FFT method to obtain.N in Format0～3 can for: 8192,4096,2048 or 1024, in form Format4, can be 4096,2048,1024,512 or 256.
839/139 extraction module is 839 or 139 points in the middle of extracting from the frequencyregion signal that N is ordered.
Therefore, in the enforcement can be:
Filter module is a low pass filter.Further, filter module can be a high order FIR filter.
Filter module can be further used for downsampled the spectral aliasing that noise and PUSCH bring not taking place in order to what guarantee 24576 points or guarantee 4096 PRACH when extracting at 839 when extracting at 139.
Downsampled module can be further used for adopting M in Format0～3 to be: 3,6,12 or 24, and be 1,2,4,8 or 16 in form Format4.
N point FFT module can be further used for adopting N in Format0～3 to be: 8192,4096,2048 or 1024, and be 4096,2048,1024,512 or 256 in form Format4.。
In the enforcement, filter module with sampling module can be cic filter.In conjunction with downsampled process, adopt cic filter to finish filtering and downsampled process simultaneously.Its role is to, do lowpass filtering, do simultaneously doubly downsampled of M as required, do the FFT computing again, extract preamble at last with cic filter.
The structure chart of the 2 rank cic filters that provided by aforesaid Fig. 6 as seen, cic filter combines filtering and abstraction module, finish filtering and downsampled process jointly, its filtering characteristic can be selected this two parameters according to the design needs fully by filtering exponent number and extracting multiple R decision.Be it can also be seen that by Fig. 6 the cic filter implementation complexity is very low, without any need for multiply operation and a large amount of storages, processing delay is also very little, is fit to very much hardware system and realizes.
In the enforcement, in equipment, can further include:
The FIR filter of low order, be connected on cic filter after, be used to make output narrowed width and passband gain smooth.Further, the response of the Frequency and Amplitude of the FIR filter of low order can be the contrary of cic filter passband response.
The effect of the FIR filter of series connection low order is behind cic filter, and generally speaking, inserting detection system at random is not very high to the requirement of PRACH demodulation part, and the 3dB decay can't influence last detection performance in the CIC band.If but wish to weaken in the band decline to Effect on Performance, the FIR filter of the low order of can behind cic filter, connect make export narrowed width and passband gain smooth.The Frequency and Amplitude response ideal situation of this compensation FIR filter should be the contrary of cic filter passband response.
According to the characteristics that are continuous distribution on frequency domain to a plurality of PRACH channels in the agreement 36.211, can handle 3 PRACH channels simultaneously, thereby save computing cycle and resource.Therefore, in the enforcement,
It is one group that frequency regulation block can be further used for 1 to 3 PRACH, the PRACH frequency that receives is adjusted near the zerofrequency simultaneously;
It is one group that filter module can be further used for 1 to 3 PRACH, suppresses the outer interference of PRACH channel simultaneously;
It is one group that downsampled module can be further used for 1 to 3 PRACH, adopts sample one time at every M sampling point simultaneously;
N point FFT module can be further used for to be one group, simultaneously N sampled point to be carried out FFT with 1 to 3 PRACH;
It is one group that 839/139 extraction module can be further used for 1 to 3 PRACH, extracts or 139 points simultaneously the frequencyregion signal of the sampled point of the N behind FFT at 839.
In concrete the enforcement, it is being one group with 1 to 3 PRACH that filter module can also be further used for, when suppressing the interference outside the PRACH channel simultaneously, with the centre of frequency spectrum shift to simultaneously treated PRACH bandwidth.
It is being one group with 1 to 3 PRACH that downsampled module can also be further used for, and when every M sampling point is adopted a sample, does 6 times of extractions simultaneously with 2 rank cic filter filtering simultaneously, obtains 4096 sampling points.
If before physical layer inserts detection at random, obtain the information of PRACH configuration and uplinkdownlink configuration, can obtain preamble sign indicating number timefrequency by tabling lookup and to insert situation from high level.Like this, in the PRACH demodulation process, just can select different processing modes and parameter as the case may be, comprise: handle several PRACH, frequency translation position, downsampled multiple M, FFT points N etc.Therefore, in the enforcement, can further include in the equipment:
Parameter determination module 1206 is used for obtaining from high level the information of PRACH configuration information and uplinkdownlink configuration before physical layer inserts detection at random; Information acquisition preamble sign indicating number timefrequency mapping according to PRACH configuration information and uplinkdownlink configuration; Determine to handle number, frequency translation position, M, N one of them or its combination of PRACH according to preamble sign indicating number timefrequency mapping.
Determine that the PRACH number is meant according to the preamble timefrequency mapping that obtains and to know the current PRACH number that may insert and time domain and frequency domain position, can select thus with one tunnel still twoway PRACH processing, and handle several PRACH simultaneously.For example, obtaining the PRACH configuration index from high level is 18, the UL/DL configuration index is 5, then can know currently have 6 PRACH and insert simultaneously, so the PRACH processing scheme selects twoway PRACH to handle, and 3 PRACH are handled on each road simultaneously by 3GPP TS 36.211 table 5.7.14, frequency spectrum shift is the center with the PRACH of centre, calculate the frequency spectrum shift point, the extracting multiple M of cic filter selects 6 simultaneously, and the FFT points N selects the preamble sign indicating number of 4096 and 3 PRACH channels to extract simultaneously.
The benefit of this scheme is a flexible configuration, according to different processing unit of different selection of configuration and suitable parameter, can maximally utilise hardware resource like this, reduces unnecessary power consumption.For example, if known may have a PRACH to insert at first field simultaneously, that just need not handle PRACH at second field again, in addition, also only need one the tunnel to handle when handling PRACH, and do not enable another road work, simultaneously, cic filter extracting multiple M can select 12 or 24, and corresponding FFT points N selects 2048 or 1024.Such processing is simple, and very beneficial to the reduction of system power dissipation, and simple CIC filters solutions has guaranteed the possibility of such flexible configuration.
For the convenience of describing, the each several part of the above device is divided into various modules with function or the unit is described respectively.Certainly, when enforcement is of the present invention, can in same or a plurality of softwares or hardware, realize the function of each module or unit.
By the foregoing description as can be known, utilize the PRACH channel only to take the characteristics of one section bandwidth in the invention process, utilize the very low cic filter of complexity to carry out filtering extraction, utilize general FFT operation to finish the demodulation of PRACH again.The all right while is according to the characteristics flexible configuration PRACH demodulation scheme of cic filter.Concrete:
The process of utilizing frequency spectrum shift, filtering, downsampled, FFT and preamble to extract in the invention process realizes the demodulating process of PRACH.
Further, can utilize the outer interference of low pass filter filters out PRACH channel strip in the enforcement, just can utilize the FFT computing demodulation of counting lower after downsampled.
Further, in the enforcement, abovementioned lowpass filtering can adopt high order FIR filter to realize.
Further, in the enforcement, abovementioned lowpass filtering adds downsampled process and can adopt cic filter to finish.
Further, in the enforcement, abovementioned cic filter adopts M＞=1 rank filtering to realize that extracting multiple can be chosen according to filtering requirements and actual needs.
Further, in the enforcement, abovementioned CIC decimation filter can further improve performance by series connection low order FIR filter.
Further, in the enforcement, can be according to PRACH and UL/DL configuration decision demodulation scheme.
Further, in the enforcement, abovementioned demodulation scheme comprises 1 road to 6 tunnel demodulation PRACH, and in the enforcement, each road can be handled 1 to 3 PRACH simultaneously.
Further, in the enforcement, abovementioned when handling several PRACH simultaneously, frequency spectrum can be moved the centre of simultaneously treated PRACH bandwidth.
Further, in the enforcement, abovementioned when handling several PRACH simultaneously, CIC extracting multiple, FFT count and extract all relevant with the PRACH treating number with preamble.
In the technical scheme provided by the invention, adopt the cic filter design, realized very high PRACH demodulating process of counting.Major advantage compared to existing technology is that flexible design and complexity are very low.The characteristic of cic filter is only relevant with extracting multiple and exponent number, therefore flexible configuration extracting multiple and filter order as required.Implement technical scheme provided by the invention and can also select PRACH demodulation scheme and parameter flexibly according to the Given information that obtains from the upper strata, and general FIR filter design flexible like this.
In addition, cic filter compares direct FFT method and FIR filtered method complexity is very low, just can realize without any need for multiplier.Even for the very high situation of performance requirement, cic filter also can be realized by the simple FIR filter of series connection low order, compare high order FIR filter and still have the low characteristics of complexity.
Those skilled in the art should understand that embodiments of the invention can be provided as method, system or computer program.Therefore, the present invention can adopt complete hardware embodiment, complete software implementation example or in conjunction with the form of the embodiment of software and hardware aspect.And the present invention can adopt the form that goes up the computer program of implementing in one or more computerusable storage medium (including but not limited to magnetic disc store, CDROM, optical memory etc.) that wherein include computer usable program code.
The present invention is that reference is described according to the flow chart and/or the block diagram of method, equipment (system) and the computer program of the embodiment of the invention.Should understand can be by the flow process in each flow process in computer program instructions realization flow figure and/or the block diagram and/or square frame and flow chart and/or the block diagram and/or the combination of square frame.Can provide these computer program instructions to the processor of allpurpose computer, specialpurpose computer, Embedded Processor or other programmable data processing device to produce a machine, make the instruction of carrying out by the processor of computer or other programmable data processing device produce to be used for the device of the function that is implemented in flow process of flow chart or a plurality of flow process and/or square frame of block diagram or a plurality of square frame appointments.
These computer program instructions also can be stored in energy vectoring computer or the computerreadable memory of other programmable data processing device with ad hoc fashion work, make the instruction that is stored in this computerreadable memory produce the manufacture that comprises command device, this command device is implemented in the function of appointment in flow process of flow chart or a plurality of flow process and/or square frame of block diagram or a plurality of square frame.
These computer program instructions also can be loaded on computer or other programmable data processing device, make on computer or other programmable devices and to carry out the sequence of operations step producing computer implemented processing, thereby the instruction of carrying out on computer or other programmable devices is provided for being implemented in the step of the function of appointment in flow process of flow chart or a plurality of flow process and/or square frame of block diagram or a plurality of square frame.
Although described the preferred embodiments of the present invention, in a single day those skilled in the art get the basic creative notion of cicada, then can make other change and modification to these embodiment.So claims are intended to all changes and the modification that are interpreted as comprising preferred embodiment and fall into the scope of the invention.
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