CN101626359A - 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 specifically relates to a frequency domain synchronous circuit structure capable of simultaneously supporting the Chinese mobile multimedia standard CMMB and the European mobile multimedia standard DVB-H. It mainly includes an integer multiple carrier frequency offset estimation module, a descrambling code module, a residual carrier frequency offset and sampling frequency offset estimation module, a control module and other parts. Integer multiple carrier frequency offset estimation module, supports integer multiple carrier frequency offset estimation of CMMB and DVB-H two standards; descrambling code module, applied to scrambling code pattern identification and descrambling code operation in CMMB mode; residual carrier frequency offset And the sampling frequency offset estimation module supports two standard residual carrier frequency offset and sampling frequency offset estimation. According to the similarity of the frequency domain structures of the two standards, the present invention proposes a structure to realize maximum multiplexing at the lowest hardware cost, thereby supporting the frequency domain synchronization of the two standards with a set of hardware structures.

Description

A Frequency Domain Synchronization Circuit Structure Suitable for CMMB and DVB-H

technical field

The invention belongs to the technical field of wireless digital communication, in particular to a frequency domain synchronous circuit structure supporting two mobile multimedia standards of CMMB and DVB-H.

Background technique

Mobile multimedia technology has now been more and more widely used. With the promulgation and implementation of China's mobile multimedia standard CMMB, mobile multimedia has been further popularized. Multi-mode and multi-standard is the development trend of mobile multimedia technology today. It is also a requirement for the development of multi-mode and multi-standard to realize the reception of programs under different standards with the same set of terminals in different regions. Synchronization technology is an important part of the receiving terminal, and its research and application in the multi-mode receiving terminal is also of great significance.

Study the main mobile multimedia standards such as the European standard DVB-H and the Chinese standard CMMB, and find that they have certain commonality in the frame structure. That is to say, they all adopt multi-carrier OFDM (orthogonal frequency division multiplexing) modulation, are all pilot-based transmission systems, and all use the time-domain symbol structure of cyclic prefix + data body and so on. The selection of the synchronization algorithm is based on the characteristics of the frame structure, so these commonalities determine that an integrated synchronization solution can be found to support each standard.

Based on the requirement of multi-mode and multi-standard and the commonality of each mobile multimedia standard in the frame structure, the present invention proposes a kind of integrated hardware structure, which can support the current two mainstream mobile multimedia standards CMMB and DVB-H at the same time, and realize maximum hardware multiplexing.

Contents of the invention

The purpose of the present invention is to provide a frequency domain synchronous circuit structure supporting both CMMB and DVB-H standards, so as to realize maximum hardware multiplexing.

According to the commonality of the frame structure of the two standards of CMMB and DVB-H, the present invention proposes a fusion hardware structure to realize the simultaneous support of the frequency domain synchronization of the two standards. Scrambling code module, residual carrier frequency offset and sampling frequency offset estimation module, each module considers the commonality of the two standards in the synchronization scheme to achieve hardware integration, and controls the work of different modules through strobe signals to achieve different The time-division multiplexing of modules to sub-modules with similar functions further improves the utilization rate of hardware. The specific structure is shown in Figure 1, and the input and output descriptions are shown in Table 1. The mode selection signal MODE_SEL controls the current working mode (CMMB or DVB-H), and inputs different parameter values for the integer times carrier frequency offset estimation module, descrambling code module, residual carrier frequency offset and sampling frequency offset estimation module. First, estimate the carrier frequency offset of integer multiples. After the estimation and compensation are completed, the completion signal IFO_DONE will be given. If the current mode is CMMB mode, the descrambling module will be started; if the current mode is DVB-H module, the residual carrier frequency offset and sampling will be started. Frequency offset estimation module. For the CMMB mode, the remaining carrier frequency offset and sampling frequency offset estimation modules are started after the descrambling code is completed.

The integer multiple carrier frequency offset estimation module is used to realize the integer multiple carrier frequency offset estimation. The specific structure is shown in Figure 2, and the input and output descriptions are shown in Table 2. It is composed of a data cache unit, a pilot position storage unit, a correlation module, a control module and a pseudo-random sequence generation module (applied to CMMB standard). The mode selection signal MODE_SEL determines the current mode of circuit work (CMMB or DVB-H), and sends it to the MUX (multiplexer) module for selection. One synchronization signal is buffered; in DVB-H mode, two consecutive OFDM symbols are buffered. (2) The read address control of the data cache unit, if the CMMB mode, then the read address control signal is the position+data offset ifo of the PN (pseudo-random) sequence; if the DVB-H mode, then the read address control signal is a continuous pilot The position + data offset. The mode selection signal also selects the working mode of the pseudo-random sequence generation module through the combinational logic gate, so that the module only works in CMMB mode. The data buffer unit reads after writing through the mode selection signal, and sends the read result to the related module for related calculation. At this time, if the current mode is CMMB mode, the result of the correlation operation needs to be correlated with the output of the pseudo-random sequence generation module; if the current mode is DVB-H mode, the result of the correlation operation is directly sent to the lower-level operation. The output of the sequence generation module is correlated and realized by controlling the MUX with the mode selection signal. The output of the MUX is sent to the accumulation-absolute value module for accumulation and absolute value. Then it is sent to the comparator, and the initial value of the comparator is set to 0. When the input value is greater than the initial value of the comparator, the current initial value will be replaced as the new initial value; if it is less than the initial value of the comparator, the original initial value will be retained. After all the preset data offset situations have been traversed, the obtained data offset ifo corresponding to the maximum value of the comparator is the estimated integer multiple carrier frequency offset. Integer carrier frequency offset is estimated and compensated, and then a completion signal is sent to drive the next-level module. If it is in CMMB mode, it will drive the descrambling code module; if it is in DVB-H mode, it will drive the residual carrier frequency offset and sampling frequency offset estimation module.

The descrambling code module is unique to the CMMB standard, and only needs to be selected to work in the CMMB mode to identify the scrambling code mode and correctly descramble the frequency domain data. The specific structure is shown in Figure 3, and the input and output descriptions are shown in Table 3. It is composed of a pseudo-random sequence generation module, a correlation module, a control module and a pilot location storage unit. The pseudo-random sequence generation module generates scrambling codes with 6 different initial values through the control SRAM_MODE of the input terminal. The pilot position storage unit stores the position of the pilot, and judges whether the current input is a pilot by reading the unit, and if it is a pilot, delays until the arrival of the pilot at the same position of the next symbol. The pilots of the two symbols are respectively descrambled by six kinds of scrambling codes generated by the pseudo-random sequence generation module, and then correlated and accumulated to generate six kinds of correlated accumulated sums. Since the pilots in two consecutive symbols are correlated after correct descrambling, the scrambling mode used to obtain the maximum value is the scrambling mode. After the scrambling mode is determined, the following symbols can be descrambled, which is realized by the conjugate-multiplication module.

The residual carrier frequency offset and sampling frequency offset estimation module is used to estimate the residual carrier frequency offset and sampling frequency offset. The specific structure is shown in Figure 4, and the input and output descriptions are shown in Table 4. It is composed of a correlation module, an argument calculation module, a pilot buffer unit and a pilot position storage unit. The mode selection signal MODE_SEL selects the current working mode, and controls the judgment of the pilot position through the MUX, so as to perform pilot caching. The cached pilots of two consecutive symbols are correlated, and then sent to the argument calculation module to calculate the argument. Then some constant coefficient operations are performed to get the final estimation result. The constant coefficients are different under CMMB and DVB-H, they are stored in advance and then selected through the mode selection signal.

Both the integer carrier frequency offset estimation module and the descrambling module use the pseudo-random sequence generation module, which only generates the initial value of the sequence. The number of shift registers is different from the feedback signal, and they do not work at the same time. Therefore, a shift register can be Group additional control signals for multiplexing. The specific structure is shown in Figure 5, and the input and output descriptions are shown in Table 5. It can be composed of a control module and a shift register group (sequence). The control module changes the initial value, the number of shift registers, and the feedback signal, so as to be applied to different modules. The mode selection signal MODE_SEL controls the working mode of the pseudo-random sequence generation module (generates a synchronization signal sequence or a scrambling code), and is selected by the selector MUX. The selection content includes: (1) The initial value of the shift register group, if the synchronization signal is generated, select The initial value of the synchronization signal; if a scrambling code is generated, select one of the 6 specific modes. (2) The number of shift register groups is 11 if synchronous signals are generated, and 12 if scrambling codes are generated. (3) The feedback signal of the shift register group, if a synchronous signal is generated, the 9th and the 11th shift registers are selected for modulo two addition and fed back to the first register; if a scrambling code is generated, the 6th is selected, 8, 11, and 12 shift registers perform modulo two addition and feed back to the first register. (4) output value, if a synchronization signal is generated, the output of the eleventh shift register is set to be valid; if a scrambling code is generated, the outputs of the ninth and twelfth shift registers are set to be valid. The above steps complete the work of the pseudo-random sequence generation module in the selected mode.

The content of the above invention can well meet the support of frequency domain synchronization under the two standards of CMMB and DVB-H, realize the integration of frequency domain synchronization of the two standards with a set of hardware structure, improve the utilization rate of hardware at the same time, and realize maximum hardware multiplexing.

Description of drawings

Figure 1 is suitable for the overall hardware structure of frequency domain synchronization for CMMB and DVB-H

Figure 2 The structure diagram of the integer times carrier frequency offset estimation module

Figure 3 Descrambling module structure diagram

Figure 4 Structure diagram of residual carrier frequency offset and sampling frequency offset estimation module

Figure 5 Pseudo-random sequence generation module structure diagram

Detailed ways

According to the scheme in the summary of the invention, the specific implementation of the frequency domain synchronization circuit applicable to CMMB and DVB-H is as follows:

(1) Firstly, estimate the carrier frequency offset of integer times.

For the CMMB standard, the integer carrier frequency offset estimation algorithm is as follows:

C(k)＝R(k)·R ^* (k+D)·PN(km)

$\stackrel{<span\; class="notranslate">\; ^</span>}{\mathrm{<span\; class="notranslate">\; ifo</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; arg</span>}\mathrm{<span\; class="notranslate">\; max</span>}<span\; class="notranslate">\; |</span>\underset{\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; \&Element;</span>\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; ifo</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}\mathrm{<span\; class="notranslate">\; C</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; |</span><span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; ifo</span>}<span\; class="notranslate">\; \&Element;</span><span\; class="notranslate">\; [</span><span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}<span\; class="notranslate">\; ,</span>}{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}<span\; class="notranslate">\; ]</span>$

Among them, R(k), R(k+D) represent the kth and k+D symbols of the synchronous signal demodulated by FFT (Fast Fourier Transform), " ^* " represents the conjugate operation, PN(km) represents Shift of the local PN sequence. Indicates the estimated integer multiple carrier frequency offset, the set M indicates the set of selected PN sequences, and the set [-i _max , i _max ] indicates the maximum integer multiple frequency offset that the algorithm can detect.

For the DVB-H standard, the integer carrier frequency offset estimation algorithm is as follows:

$\mathrm{<span\; class="notranslate">\; C</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; Z</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; Z</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}^{<span\; class="notranslate">\; *</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span>$

$\stackrel{<span\; class="notranslate">\; ^</span>}{\mathrm{<span\; class="notranslate">\; ifo</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; arg</span>}\mathrm{<span\; class="notranslate">\; max</span>}<span\; class="notranslate">\; |</span>\underset{\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; \&Element;</span>\mathrm{<span\; class="notranslate">\; P</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; ifo</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}\mathrm{<span\; class="notranslate">\; C</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; |</span><span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; ifo</span>}<span\; class="notranslate">\; \&Element;</span><span\; class="notranslate">\; [</span><span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}<span\; class="notranslate">\; ,</span>}{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}<span\; class="notranslate">\; ]</span>$

Among them, Z _n (k), Z _n-1 (k) respectively represent the k-th symbol in the nth and n-1th OFDM signals after FFT, and the set P represents the set of continuous pilots, and the set [-i _max , i _max ] represents the maximum integer multiple frequency offset that the algorithm can detect.

It can be found that both algorithms are based on correlation-finding the maximum value, but the data to be cached and the correlation methods are different. So it can be handled as follows:

For the data buffer unit, when the current mode is CMMB, one synchronization signal is buffered; when the current mode is DVB-H, two consecutive OFDM symbols are buffered.

When the current mode is CMMB, read the symbols in the data buffer unit continuously for delay correlation; when the current mode is DVB-H, read the symbols in the data buffer unit by reading the position of the pilot in the pilot position storage unit for delay correlation. relevant.

When the current mode is CMMB, the result after correlation needs to be multiplied by PN(k-m), and PN(k-m) is generated by the pseudo-random sequence generation module. However, since the values of PN(k-m) are 1 and -1, the multiplication only needs to be realized by inverting the multiplicand or taking the original value.

The result of correlation accumulation is sent to the control module to determine the maximum value. When the set [-i _max , i _max ] is traversed, the ifo value of the maximum value obtained is the estimated integer multiple frequency offset.

The integer multiple frequency offset estimation module only needs to work once, and the integer multiple carrier frequency offset estimation and correction will give a completion signal. For DVB-H system, start the residual carrier frequency offset and sampling frequency offset estimation module; for CMMB system, start descrambling Code module, this module is unique to CMMB system.

(2) The algorithm of the descrambling module is as follows:

According to "The continuous pilots of two adjacent OFDM symbols that are correctly descrambled are correlated", the scrambling code pattern recognition algorithm is as follows:

${\mathrm{<span\; class="notranslate">\; the\; s</span>}}_{\mathrm{<span\; class="notranslate">\; cram</span>}}<span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; \&Element;</span><span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; 0,5</span>}<span\; class="notranslate">\; ]</span>}{\mathrm{<span\; class="notranslate">\; arg</span>}\mathrm{<span\; class="notranslate">\; max</span>}}<span\; class="notranslate">\; |</span>\underset{\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; \&Element;</span>\mathrm{<span\; class="notranslate">\; P</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}<span\; class="notranslate">\; [</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; Z</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; i</span>}}^{<span\; class="notranslate">\; *</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; \&times;</span>{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; V</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&CenterDot;</span>{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; Z</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; i</span>}}^{<span\; class="notranslate">\; *</span>}<span\; class="notranslate">\; (</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&times;</span>{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; V</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span>}^{<span\; class="notranslate">\; *</span>}<span\; class="notranslate">\; ]</span><span\; class="notranslate">\; |</span>$

where P _{c, i} (k), i∈[0,5] represent the scrambling code values in different scrambling modes, and N _V represents the number of valid subcarriers (including data subcarriers and pilots) in each OFDM symbol . P _{c, i} (k) has six values in total, which are generated by the pseudo-random sequence generation module.

可以看作同±1±i相乘，因此相乘只需对被乘数取反或者取原值实现。Descrambling can be performed after the scrambling mode is determined, and the descrambling is completed by multiplying the OFDM symbol after FFT by P _c,i (k). Since P _{c, the value of i} (k) is

It can be regarded as multiplication with ±1±i, so the multiplication only needs to invert the multiplicand or take the original value to realize.

The descrambling module needs to work all the time. For the CMMB mode, after each OFDM symbol is descrambled and a completion signal is given, the residual carrier frequency offset and sampling frequency offset estimation modules can be started.

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

For both standards, the algorithms for residual carrier frequency offset and sampling frequency offset estimation can be expressed as follows:

$\mathrm{<span\; class="notranslate">\; D.</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; Z</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; Z</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}^{<span\; class="notranslate">\; *</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; \&Element;</span>\mathrm{<span\; class="notranslate">\; P</span>}$

$\mathrm{<span\; class="notranslate">\; \&beta;</span>}<span\; class="notranslate">\; =</span>\frac{\underset{\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; \&Element;</span>\mathrm{<span\; class="notranslate">\; <figure-callout\; id="1"\; label="P"\; filenames="A2009100561400013H1.png,A2009100561400015H1.png"\; state="\{\{state\}\}">P</figure-callout></span>}\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}\mathrm{<span\; class="notranslate">\; arg</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; D.</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>\underset{\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; \&Element;</span>\mathrm{<span\; class="notranslate">\; P</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}\mathrm{<span\; class="notranslate">\; arg</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; D.</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; (</span>\underset{\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; \&Element;</span>\mathrm{<span\; class="notranslate">\; P</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; -</span>\underset{\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; \&Element;</span>\mathrm{<span\; class="notranslate">\; P</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; ,</span>$ $\mathrm{<span\; class="notranslate">\; \&epsiv;</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}\mathrm{<span\; class="notranslate">\; arg</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; D.</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&CenterDot;</span>\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; -</span>\frac{\underset{\mathrm{<span\; class="notranslate">\; P</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; +</span>\underset{\mathrm{<span\; class="notranslate">\; P</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}\mathrm{<span\; class="notranslate">\; k</span>}}{\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}\mathrm{<span\; class="notranslate">\; \&beta;</span>}$

Among them, the set P represents the set of continuous pilots, the sets P1 and P2 respectively represent the first half and the second half of the continuous pilots, M represents the number of selected continuous pilots, N _s , and N represent the cyclic prefix and non-cyclic prefix respectively OFDM symbol length has different values in both CMMB and DVB-H standards. β is the estimated sampling frequency offset and ε is the estimated residual carrier frequency offset.

It can be seen that the basic operations of this module are the same, but the sets P corresponding to different standards are different. Therefore, it is only necessary to store the positions of continuous pilots under the two standards in different pilot position storage units, and select and read different pilot position storage units according to the current mode, thereby buffering different signals in the pilot buffer unit. The cached signal is correlated, the argument is calculated, and then different N _s , N, M values are selected according to different modes to complete the calculation of the residual frequency offset and sampling frequency offset.

(4) Multiplexing of the same hardware among different modules:

Correlation modules are used in the three modules of integer carrier frequency offset estimation, descrambling code, residual carrier frequency offset and sampling frequency offset estimation. The essence of the correlation is the multiplication and summation of complex numbers. Since the three modules do not work at the same time, the related modules can be time-division multiplexed among the three main modules. Since the relevant timing requirements are not strict, there is no need for parallel multiplication and summation, so only one complex multiplier and one accumulator can be used, which greatly reduces the hardware cost.

In CMMB mode, both the integer carrier frequency offset estimation and descrambling modules use the pseudo-random sequence generation module, and the two modules do not work at the same time. Therefore, a pseudo-random sequence generation module can be shared, and the initial value of the module, the number of shift registers, and the feedback signal can be made configurable, which can be applied to the above two modules. The specific structure is shown in Figure 5, and the input and output description As shown in Table 5.

In the above scheme, the hardware fusion multiplexing proposed by the present invention is used. Compared with the single-mode frequency domain synchronization scheme, only some control circuits and small storage units are added, which can realize frequency domain synchronization under the two standards. Support, with a set of hardware structure to realize the fusion of CMMB and DVB-H two standard frequency domain synchronization.

Table 1. Input and output description of the overall hardware structure diagram

Table 2. Integer times carrier frequency offset estimation module input and output description

Table 3. Descrambling code descrambling module input and output description

Table 4. Residual carrier frequency offset and sampling frequency offset estimation module input and output description

Table 5. Description of the input and output of the pseudo-random sequence generation module

Claims (6)

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 deviation and sampling frequency offset estimation module constitute;

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 deviation and sampling frequency offset estimation module support the residual carrier frequency deviation 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 the residual carrier frequency deviation 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 after estimation and compensation are finished and finish signal IFO_DONE,, after descrambling code is finished, start over-carriage ripple frequency deviation and sampling frequency offset estimation module if present mode is that the CMMB pattern then starts the descrambling code module; If present mode is that the DVB-H module then starts residual carrier frequency deviation and sampling frequency offset estimation module.

2. circuit structure according to claim 1, it is characterized in that in two kinds of standards, the estimation of integral multiple carrier deviation estimation module all is based on the relevant of frequency domain signal specific, it is by data buffer storage unit, the pilot frequency locations memory cell, correlation module, control module and pseudo random sequence generation module are formed;

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) address of reading of data buffer storage unit is controlled, if the CMMB pattern, then reading address control signal is the position+data-bias ifo of PN sequence; If the DVB-H pattern is then read position+data-bias that address control signal is a 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 finishing, and the result that will read out sends into correlation module and carries out related operation; This moment, the result of related operation also needed to be correlated with the output of pseudo random sequence generation module if present mode is the CMMB pattern; 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 sends into and adds up-and absolute value block adds up and asks 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 finished, the data-bias ifo of the comparator maximum correspondence that obtains was exactly the integer-time carrier wave frequency deviation of estimating; Send after integral multiple carrier deviation estimation and the compensation and finish signal, 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 deviation and sampling frequency offset estimation module.

3. circuit structure according to claim 1 is characterized in that, the descrambling code module is finished the 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 are formed;

The pseudo random sequence generation module produces the scrambler of 6 kinds of different initial values respectively by input control SRAM_MODE; The position of pilot frequency locations cell stores pilot tone judges that by reading this unit current input is a pilot tone, if pilot tone then postpones to arrive up to the same position pilot tone of next symbol; 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 and add up, produces six kinds be correlated with 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 pattern is determined, realize by the conjugation-module that multiplies each other.

4. circuit structure according to claim 1, it is characterized in that, in two kinds of standards, residual carrier frequency deviation 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 deviation and sampling frequency offset estimation module are by correlation module, the argument computing module, pilot tone buffer unit and pilot frequency locations memory cell are formed;

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, send into the argument computing module then and ask the argument computing, carry out then obtaining final estimated result after some constant coefficient computings.

5. according to claim 2,3 or 4 described circuit structures; It is characterized in that correlation module is the Multiplexing module of integral multiple carrier deviation estimation module, descrambling code module, residual carrier frequency deviation and sampling frequency offset estimation module, and not in synchronization work, correlation module adopts serial relevant, and only uses a complex multiplier.

6. according to claim 2 or 3 described circuit structures, it is characterized in that the pseudo random sequence generation module is the Multiplexing module of integral multiple carrier deviation estimation module and descrambling code module, it 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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