CN101626359B - Frequency-domain synchronous circuit structure applicable to CMMB and DVB-H - Google Patents

Abstract

The invention belongs to the technical field of wireless digital communication, and particularly relates to a frequency-domain synchronous circuit structure which can support the China mobile multimedia standard CMMB and European mobile multimedia standard DVB-H simultaneously. The frequency-domain synchronous circuit structure mainly comprises an integral multiple carrier deviation estimation module, a descrambling module, a residual carrier deviation and sampling deviation estimation module, a control module and the like. The integral multiple carrier deviation estimation module supports the integral multiple carrier deviation estimation with two types of standards, namely CMMB and DVB-H; the descrambling module is applied to scrambling mode recognition under the CMMB mode and descrambling operation; and the residual carrier deviation and sampling deviation estimation module supports the residual carrier deviation and sampling deviation estimation with two types of standards. According to the similarity of the frequency domain structures with two types of standards, the frequency-domain synchronous circuit structure discloses a structure which realizes the maximum multiplexing by lowest hardware cost, thus using one set of hardware structures to support the frequency domain synchronization with two types of standards.

Description

A kind of frequency-domain synchronous circuit structure that is applicable to CMMB and DVB-H

Technical field

The invention belongs to the radio digital communication technical field, be specifically related to a kind of frequency-domain synchronous circuit structure of supporting simultaneously CMMB and two kinds of mobile multimedia standards of DVB-H.

Background technology

Nowadays Technology of Mobile Multimedia has been able to use more and more widely.Along with the issuing and implementation of the multimedia standardization CMMB of China Mobile, mobile multimedia has obtained further popularizing.The many standards of multimode are the trend of current Technology of Mobile Multimedia development, realize that in different geographical the reception to program under the various criterion also is the requirement of the many standard evolution of multimode with same set of terminal.Simultaneous techniques is as part and parcel in the receiving terminal, and its research in the multimode receiving terminal is used and also had very important significance.

Research is main mobile multimedia standard such as European standard DVB-H at present, and Chinese Industrial Standards (CIS) CMMB finds that they have certain general character at frame structure.Namely all adopt multi-carrier OFDM (OFDM) modulation system, all be based on the transmission system of pilot tone, all adopted time-domain symbol structure of Cyclic Prefix+data volume etc.Choosing of synchronized algorithm then is feature according to frame structure, so these general character have determined that the synchronization scenario that can seek a kind of fusion supports each standard.

Demand and the general character of each mobile multimedia standard on frame structure based on the many standards of multimode, the present invention proposes a kind of hardware configuration of fusion, can support simultaneously mobile multimedia standard C MMB and the DVB-H of present two kinds of main flows, realize maximum hardware multiplexing.

Summary of the invention

The object of the invention is to provide a kind of frequency-domain synchronous circuit structure of supporting simultaneously CMMB and two kinds of standards of DVB-H, realizes maximum hardware multiplexing.

The present invention is the general character on frame structure according to CMMB and two kinds of standards of DVB-H, a kind of hardware configuration of fusion has been proposed, realize simultaneously to two kinds of supports that the standard frequency domain is synchronous, mainly by integral multiple carrier deviation estimation module, the descrambling code module, residual carrier frequency offset and sampling frequency offset estimation module consist of, thereby each module has been considered the general character of two kinds of standards on synchronization scenario and has been realized that hardware merges, and the work by gating signal control disparate modules, thereby realize that disparate modules to the time-sharing multiplex of identity function submodule, has further improved the hardware utilance.Concrete structure as shown in Figure 1, inputoutput specification is as shown in table 1.Mode select signal MODE_SEL controls work at present pattern (being CMMB or DVB-H), and is integral multiple carrier deviation estimation module, the descrambling code module, and residual carrier frequency offset is sent into different parameter values with the sampling frequency offset estimation module.At first carry out the estimation of integer-time carrier wave frequency deviation, provide settling signal IFO_DONE after estimation and compensation are finished, then start the descrambling code module if present mode is the CMMB pattern; If being the DVB-H module, present mode then starts residual carrier frequency offset and sampling frequency offset estimation module.After finishing, descrambling code starts over-carriage ripple frequency deviation and sampling frequency offset estimation module for the CMMB pattern.

Integral multiple carrier deviation estimation module is in order to realize the estimation of integer-time carrier wave frequency deviation.Concrete structure as shown in Figure 2, inputoutput specification is as shown in table 2.By data buffer storage unit, the pilot frequency locations memory cell, correlation module, control module and pseudo random sequence generation module (being applied to the CMMB standard) form.The present mode of mode select signal MODE_SEL decision-making circuit work (being CMMB or DVB-H), sending into MUX (MUX) module selects, chosen content has: the cache contents of (1) data buffer storage unit, if CMMB pattern, then synchronizing signal of buffer memory; If DVB-H pattern, then two continuous OFDM symbols of buffer memory.(2) data buffer storage unit read address control, if the CMMB pattern is then read address control signal and is the position of PN (pseudorandom) sequence+data-bias ifo; If the DVB-H pattern is then read position+data-bias that address control signal is continuous pilot.Mode select signal is also selected the mode of operation of pseudo random sequence generation module by combinational logic gate, this module is only worked under the CMMB pattern.Data buffer storage unit writes by mode select signal and reads after complete, and the result that will read out sends into correlation module and carries out related operation.If this moment, present mode was the CMMB pattern, the result of related operation also needs to be correlated with the output of pseudo random sequence generation module; Whether if present mode is the DVB-H pattern, then the result of related operation directly sends into subordinate's computing, be correlated with by mode select signal control MUX realization with the output of pseudo random sequence generation module.The output of this MUX is sent into cumulative-absolute value block and is added up and ask absolute value.Then send into comparator, the initial value of comparator is made as 0.When input value during greater than the comparator initial value, then replacing current initial value becomes new initial value; If then keep original initial value less than the comparator initial value.After all default data-bias situation traversals were complete, data-bias ifo corresponding to comparator maximum that obtains was exactly the integer-time carrier wave frequency deviation of estimating.Send settling signal after integral multiple carrier deviation estimation and the compensation, drive the next stage module.If the CMMB pattern then drives the descrambling code module; If the DVB-H pattern then drives residual carrier frequency offset and sampling frequency offset estimation module.

The descrambling code module, peculiar for the CMMB standard, only need gating work under the CMMB pattern, in order to the identification of scrambler pattern and to the correct descrambling of frequency domain data.Concrete structure as shown in Figure 3, inputoutput specification is as shown in table 3.By the pseudo random sequence generation module, correlation module, control module and pilot frequency locations memory cell form.The pseudo random sequence generation module produces respectively the scrambler of 6 kinds of different initial values by the control SRAM_MODE of input.The position of pilot frequency locations cell stores pilot tone judges that by reading this unit current input is pilot tone, and the same position pilot tone of next symbol arrives if pilot tone then postpones.Be correlated with again behind 6 kinds of scrambler descramblings that the pilot tone of two symbols produces with the pseudo random sequence generation module respectively cumulative, produces six kinds relevant add up with.Because the pilot tone in correct latter two continuous symbol of descrambling has correlation, therefore obtaining the scrambler mode that maximum takes is exactly the scrambler pattern.Can carry out descrambling to symbol afterwards after the scrambler mode decision, realize by the conjugation-module that multiplies each other.

Residual carrier frequency offset and sampling frequency offset estimation module are in order to estimate residual carrier frequency offset and sampling frequency offset.Concrete structure as shown in Figure 4, inputoutput specification is as shown in table 4.By correlation module, the argument computing module, pilot tone buffer unit and pilot frequency locations memory cell form.Mode select signal MODE_SEL selects the pattern of work at present, judgement by MUX control pilot frequency locations, thereby carry out the pilot tone buffer memory, the pilot tone of continuous two symbols of buffer memory is correlated with, then send into the argument computing module and ask the argument computing, then carry out obtaining final estimated result after some constant coefficient computings.Constant coefficient is different under CMMB and DVB-H, and then in advance storage is selected by mode select signal.

All used the pseudo random sequence generation module in integral multiple carrier deviation estimation module and the descrambling code module, it is the initial value of formation sequence, the shift register number is different with feedback signal, and does not work simultaneously, therefore can carry out multiplexing to the additional control signal of a shift register group.Concrete structure as shown in Figure 5, inputoutput specification is as shown in table 5.It can be comprised of control module and shift register group (sequence), and control module changes initial value, shift register number, feedback signal, thereby is applied to different modules.The mode of operation (generating synchronous signal sequence or scrambler) of mode select signal MODE_SEL control pseudo random sequence generation module, select by selector MUX, chosen content has: the initial value of (1) shift register group, if generate the initial value that synchronizing signal is then selected synchronizing signal; Then select a certain in concrete 6 kinds of patterns if generate scrambler.(2) number of shift register group then is 11 if generate synchronizing signal; Then be 12 if generate scrambler.(3) feedback signal of shift register group, if generate synchronizing signal then the 9th and the 11st shift register of gating carry out mould two additions and feed back to the 1st register; If generate scrambler then the 6th, 8,11,12 shift registers of gating carry out mould two additions and feed back to the 1st register.(4) output valve, the generation synchronizing signal is then established the 11st shift register and is output as effectively; If the generation scrambler is then established the 9th and the 12nd shift register and is output as effectively.Above step is finished the work of pseudo random sequence generation module under institute's lectotype.

The foregoing invention content can satisfy well to the synchronous support of frequency domain under CMMB and two kinds of standards of DVB-H, has realized two kinds of fusions that the standard frequency domain is synchronous with a cover hardware configuration, improves simultaneously the hardware utilance, realizes maximum hardware multiplexing.

Description of drawings

Fig. 1 is applicable to the synchronous whole hardware structure diagram of frequency domain of CMMB and DVB-H

Fig. 2 integral multiple carrier deviation estimation module structure chart

Fig. 3 descrambling code modular structure figure

Fig. 4 residual carrier frequency offset and sampling frequency offset estimation module structure chart

Fig. 5 pseudo random sequence generation module structure chart

Embodiment

According to the scheme in the summary of the invention, the embodiment of frequency-domain synchronous circuit that is applicable to CMMB and DVB-H is as follows:

(1) at first carries out the estimation of integer-time carrier wave frequency deviation.

For the CMMB standard, the integral multiple carrier deviation estimation algorithm is as follows:

C(k)＝R(k)·R ^*(k+D)·PN(k-m)

$\widehat{\mathrm{ifo}}=\arg \max \left|\underset{k\∈M+\mathrm{ifo}}{\mathrm{\Σ}}C\left(k\right)\right|,\mathrm{ifo}\∈[-i_{\max ,}{i}_{\max }]$

R (k) wherein, k and k+D the symbol of the synchronizing signal after R (k+D) expression FFT (fast fourier transform) demodulation, " ^*" the expression conjugate operation, PN (k-m) represents local PN shifting of sequence. The integer-time carrier wave frequency deviation that expression is estimated, set M represents the set of selected PN sequence, set [i _Max, i _Max] the expression algorithm maximum integer times frequency deviation that can detect.

For the DVB-H standard, the integral multiple carrier deviation estimation algorithm is as follows:

$C\left(k\right)=Z_n\left(k\right)\·Z_{n-1}^{*}\left(k\right)$

$\widehat{\mathrm{ifo}}=\arg \max \left|\underset{k\∈P+\mathrm{ifo}}{\mathrm{\Σ}}C\left(k\right)\right|,\mathrm{ifo}\∈[-i_{\max ,}{i}_{\max }]$

Z wherein _n(k), Z _N-1(k) represent respectively behind the FFT k symbol in n and n-1 the ofdm signal, gather the set that P represents continuous pilot, gather [i _Max, i _Max] the expression algorithm maximum integer times frequency deviation that can detect.

Can find that two kinds of algorithms all are based on the method for relevant-maximizing, just need the data of buffer memory and relevant mode not identical.Therefore can followingly process:

For data buffer storage unit, when present mode is CMMB, synchronizing signal of buffer memory; When present mode is DVB-H, two continuous OFDM symbols of buffer memory.

When present mode was CMMB, the symbol in the reading out data buffer unit postponed to be correlated with continuously; When present mode is DVB-H, come the symbol in the reading out data buffer unit to be correlated with by the position of reading pilot tone in the pilot frequency locations memory cell.

When present mode was CMMB, the result after being correlated with need multiply by PN (k-m), and PN (k-m) is produced by the pseudo random sequence generation module.But because the value of PN (k-m) is 1 and-1, the need that only therefore multiply each other are with to the multiplicand negate or get initial value and realize getting final product.

Relevant cumulative result sends into control module, judges maximum, as set [i _Max, i _Max] travel through when complete, obtained peaked ifo value namely is estimated integer frequency offset.

The integer frequency offset estimation module only needs work once, provides settling signal after integral multiple carrier deviation estimation and the correction, for the DVB-H system, starts residual carrier frequency offset and sampling frequency offset estimation module; For the CMMB system, start the descrambling code module, this module is that the CMMB system is peculiar.

(2) algorithm of descrambling code module is as follows:

According to " continuous pilot of the two adjacent OFDM symbol of correct descrambling has correlation ", the scrambler algorithm for pattern recognition is as follows:

$s_{\mathrm{cram}}=\underset{i\∈\left[\mathrm{0,5}\right]}{\arg \max }\left|\underset{k\∈P}{\mathrm{\Σ}}\right[(Z_n\left(k\right)\·P_{c,i}^{*}(n\×N_V+k))\·{(Z_{n-1}\left(k\right)\·P_{c,i}^{*}((n-1)\×N_V+k))}^{*}\left]\right|$

P wherein _{C, i}(k), i ∈ [0,5] represents the scrambler value under the different scrambler patterns, N _VRepresent effective subcarrier (comprising data subcarrier and pilot tone) number in each OFDM symbol.P _{C, i}(k) have six kinds of values, produced by the pseudo random sequence generation module.

Can carry out descrambling after the scrambler mode decision, the OFDM symbol same P of descrambling after by FFT _{C, i}(k) multiply each other and finish.Because P _{C, i}(k) value is

Can regard as with ± 1 ± i and multiply each other, therefore multiply each other and only need or get initial value and realize the multiplicand negate.

The descrambling code module need to be worked always.For the CMMB pattern, provide settling signal behind each OFDM symbolic solution scrambler, can start residual carrier frequency offset and sampling frequency offset estimation module.

(3) algorithm of residual carrier frequency offset and sampling frequency offset estimation module is as follows:

For two kinds of standards, the algorithm that residual carrier frequency offset and sampling frequency offset are estimated all can be represented by the formula:

$D\left(k\right)=Z_n\left(k\right)\·Z_{n-1}^{*}\left(k\right),k\∈P$

$\mathrm{\&beta;}=\frac{\underset{k\&Element;\mathrm{<figure-callout\; id="1"\; label="P"\; filenames="H200910056140XE00011.png,H200910056140XE00021.png"\; state="\{\{state\}\}">P</figure-callout>}1}{\mathrm{\&Sigma;}}\arg \left(D\left(k\right)\right)-\underset{k\&Element;P2}{\mathrm{\&Sigma;}}\arg \left(D\left(k\right)\right)}{2\mathrm{\&pi;}(N_s/N)(\underset{k\&Element;P1}{\mathrm{\&Sigma;}}k-\underset{k\&Element;P2}{\mathrm{\&Sigma;}}k)},$ $\mathrm{\&epsiv;}=\frac{\mathrm{\&Sigma;}\arg \left(D\left(k\right)\right)}{2\mathrm{\&pi;}(N_s/N)\&CenterDot;M}-\frac{\underset{P2}{\mathrm{\&Sigma;}}k+\underset{P2}{\mathrm{\&Sigma;}}k}{M-1}\mathrm{\&beta;}$

Wherein gather P and represent the set of continuous pilot, set P1, P2 represents respectively the first half and the later half of continuous pilot, M represents the continuous pilot number chosen, N _s, N represents respectively to contain Cyclic Prefix and does not contain Cyclic Prefix OFDM symbol lengths, in CMMB and DVB-H standard different values is arranged.The sampling frequency offset of β for estimating, the residual carrier frequency offset of ε for estimating.

The basic operation that can find out this module is identical, is that corresponding various criterion set P is different.Therefore only need the position of continuous pilot under two kinds of standards is stored in different pilot frequency locations memory cell, select to read different pilot frequency locations memory cell according to present mode, thus in the pilot tone buffer unit the different signal of buffer memory.The signal of buffer memory is correlated with, and argument is calculated, and then chooses different N according to different patterns _s, N, the M value is finished the calculating of residual frequency deviation and sampling frequency offset.

(4) multiplexing between disparate modules of same hardware:

In integral multiple carrier deviation estimation, descrambling code, residual carrier frequency offset and sampling frequency offset are estimated all to have used correlation module in three modules.Relevant be in the nature complex multiplication and summation.Because three modules do not work simultaneously, thus correlation module can be in three primary modules time-sharing multiplex.Because relevant not strict to the requirement of sequential, not needing walk abreast multiplies each other and sues for peace, so can only use a complex multiplier and an accumulator, greatly reduces hardware costs.

Under the CMMB pattern, integral multiple carrier deviation estimation and descrambling code module have all been used the pseudo random sequence generation module, and these two modules are not worked simultaneously.Therefore can share a pseudo random sequence generation module, with the initial value of this module, the shift register number, feedback signal is made configurable, namely can be applicable to above-mentioned two modules, concrete structure as shown in Figure 5, inputoutput specification is as shown in table 5.

In such scheme, the hardware that has used the present invention to propose merges multiplexing, frequency domain synchronization scenario with monotype is compared, some control circuits and little memory cell have only been added, can realize the synchronous support of frequency domain under two kinds of standards, realize CMMB and two kinds of synchronous fusions of standard frequency domain of DVB-H with a cover hardware configuration.

The whole hardware structure diagram inputoutput specification of table 1.

Table 2. integral multiple carrier deviation estimation module inputoutput specification

Table 3. descrambling code descrambling code module inputoutput specification

Table 4. residual carrier frequency offset and sampling frequency offset estimation module inputoutput specification

Table 5. pseudo random sequence generation module inputoutput specification

Claims (3)

1. a frequency-domain synchronous circuit structure that is applicable to CMMB and DVB-H is characterized in that, by integral multiple carrier deviation estimation module, and the descrambling code module, residual carrier frequency offset and sampling frequency offset estimation module consist of;

Integral multiple carrier deviation estimation module, the integral multiple carrier deviation estimation of support CMMB and two kinds of standards of DVB-H;

The descrambling code module is applied to the computing of scrambler pattern recognition and descrambling code under the CMMB pattern;

Residual carrier frequency offset and sampling frequency offset estimation module support the residual carrier frequency offset of two kinds of standards and sampling frequency offset to estimate;

Mode select signal MODE_SEL control work at present pattern is CMMB or DVB-H, and is integral multiple carrier deviation estimation module, the descrambling code module, and residual carrier frequency offset is sent into different parameter values with the sampling frequency offset estimation module; At first carry out the estimation of integer-time carrier wave frequency deviation, provide settling signal IFO_DONE after estimation and compensation are finished, then start the descrambling code module if present mode is the CMMB pattern, after descrambling code is finished, start over-carriage ripple frequency deviation and sampling frequency offset estimation module; If being the DVB-H module, present mode then starts residual carrier frequency offset and sampling frequency offset estimation module;

In described two kinds of standards, the estimation of integral multiple carrier deviation estimation module all is based on the relevant of frequency domain signal specific, and it is by data buffer storage unit, the pilot frequency locations memory cell, and correlation module, control module and pseudo random sequence generation module form;

The present mode of mode select signal MODE_SEL decision-making circuit work is CMMB or DVB-H, sending into MUX MUX module selects, chosen content has: the cache contents of (1) data buffer storage unit, if CMMB pattern, then synchronizing signal of buffer memory; If DVB-H pattern, then two continuous OFDM symbols of buffer memory; (2) data buffer storage unit read address control, if the CMMB pattern, the position of then reading address control signal and be the PN sequence adds data skew ifo; If the DVB-H pattern, the position of then reading address control signal and be continuous pilot adds the data skew; Mode select signal is also selected the mode of operation of pseudo random sequence generation module by combinational logic gate, this module is only worked under the CMMB pattern; Data buffer storage unit writes by mode select signal and reads after complete, and the result that will read out sends into correlation module and carries out related operation; If this moment, present mode was the CMMB pattern, the result of related operation also needs to be correlated with the output of pseudo random sequence generation module; Whether if present mode is the DVB-H pattern, then the result of related operation directly sends into subordinate's computing, be correlated with by mode select signal control MUX realization with the output of pseudo random sequence generation module; The output of this MUX is sent into cumulative-absolute value block and is added up and ask absolute value; Then send into comparator, the initial value of comparator is made as 0; When input value during greater than the comparator initial value, then replacing current initial value becomes new initial value; If input value then keeps original initial value less than the comparator initial value; After all default data-bias situation traversals were complete, data-bias ifo corresponding to comparator maximum that obtains was exactly the integer-time carrier wave frequency deviation of estimating; Send settling signal after integral multiple carrier deviation estimation and the compensation, drive the next stage module; If the CMMB pattern then drives the descrambling code module; If the DVB-H pattern then drives residual carrier frequency offset and sampling frequency offset estimation module;

Described descrambling code module is finished pattern recognition and the descrambling code of scrambler, by the pseudo random sequence generation module, and correlation module, control module and pilot frequency locations memory cell form;

The pseudo random sequence generation module produces respectively the scrambler of 6 kinds of different initial values by the control signal SRAM MODE of input; The position of pilot frequency locations cell stores pilot tone judges that by reading this unit current input is pilot tone, and the same position pilot tone of next symbol arrives if pilot tone then postpones; Be correlated with again behind 6 kinds of scrambler descramblings that the pilot tone of two symbols produces with the pseudo random sequence generation module respectively cumulative, produces six kinds relevant add up with; Obtaining the scrambler mode that maximum takes is exactly the scrambler pattern; Can carry out descrambling to symbol afterwards after the scrambler mode decision, realize by the conjugation-module that multiplies each other;

In two kinds of standards, residual carrier frequency offset and sampling frequency offset are estimated by the relevant of continuous pilot in the adjacent two symbols and are got argument and finish, residual carrier frequency offset and sampling frequency offset estimation module be by correlation module, the argument computing module, and pilot tone buffer unit and pilot frequency locations memory cell form;

Mode select signal MODE_SEL selects the pattern of work at present, judgement by MUX control pilot frequency locations, thereby carry out the pilot tone buffer memory, the pilot tone of continuous two symbols of buffer memory is correlated with, then send into the argument computing module and ask the argument computing, then carry out obtaining final estimated result after some constant coefficient computings;

Wherein, correlation module is the Multiplexing module of integral multiple carrier deviation estimation module, descrambling code module, residual carrier frequency offset and sampling frequency offset estimation module; The pseudo random sequence generation module is the Multiplexing module of integral multiple carrier deviation estimation module and descrambling code module.

2. circuit structure according to claim 1, the Multiplexing module that it is characterized in that integral multiple carrier deviation estimation module, descrambling code module, residual carrier frequency offset and sampling frequency offset estimation module is correlation module, not in synchronization work, correlation module adopts Series correlation, and only uses a complex multiplier.

3. circuit structure according to claim 1, the Multiplexing module that it is characterized in that integral multiple carrier deviation estimation module and descrambling code module is the pseudo random sequence generation module, is made of control module and shift-register sequence; Control module changes initial value, shift register number, feedback signal, thereby is applied to disparate modules.

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