KR100803130B1 - Apparatus and method for receiving digital multimedia broadcasting - Google Patents

Abstract

Disclosed are a digital multimedia broadcasting receiving apparatus and method. The apparatus includes first and second tuners for receiving and converting a wireless signal for digital multimedia broadcasting into first and second baseband signals; First and second analog / digital converters which operate in response to an operating power source and convert the first and second baseband signals into digital signals; First and second automatic gain adjusters for normalizing the power of the result converted by the first and second analog / digital converters and outputting the normalized result to the first and second tuners; First and second low pass filters for low pass filtering the normalized results output from the first and second automatic gain adjusters and for outputting a low pass filtered result to the first and second tuners; A power supply unit selectively supplying the operating power to at least one of the first and second analog / digital converters in accordance with the reception performance of the digital multimedia broadcasting wireless signal; And a performance checking unit for checking a reception performance of the digital multimedia broadcasting radio signal and outputting the checked reception performance to the power supply unit.

Description

Apparatus and method for receiving digital multimedia broadcasting

1 is a block diagram schematically illustrating a TDS-OFDM transmitter.

2 is a diagram illustrating a structure of a transmission frame of a signal transmitted by a TDS-OFDM transmitter.

3 is a conceptual block diagram of a DMB-T receiver.

4 is a conceptual block diagram of a Chinese DMB-H receiver.

5 is a block diagram of an embodiment of a digital multimedia broadcasting receiving apparatus according to the present invention.

6 is a flowchart for explaining an embodiment of a digital multimedia broadcasting reception method according to the present invention.

The present invention relates to digital multimedia broadcasting (DMB), and more particularly, to an apparatus and a method for receiving digital multimedia broadcasting.

Recently, China's Tsinghua University has proposed a new standard for its terrestrial digital television broadcasting. This proposal is called Terrestrial Digital Multimedia / Television Broadcasting (DMB-T). DMB-T uses a new modulation scheme called Time Domain Synchronous (TDS) Orthogonal Frequency Division Multiplexing (OFDM) (hereinafter referred to as TDS-OFDM). A transmitter using this scheme uses an Inverse Discrete Fourier Transform (IDFT) such as Cyclic Prefix OFDM (hereinafter referred to as CP-OFDM). In addition, this method uses PN (Pseudo Noise) instead of CP in the Guard Interval to implement frame sync, channel estimation, and phase noise tracking. Use it as a training signal. That is, a combination of CDMA and OFDM schemes in which a PN sequence in a time domain and payload data in a frequency domain are combined to transmit a signal reduces transmission overhead and increases channel efficiency to increase synchronization and channel estimation. It can improve performance.

On the other hand, DMB-H (where H means handheld) is a technical specification that adds, complements, and develops DMB-T for transmitting multimedia data to portable terminals while maintaining full backward compatibility with DMB-T transmission network. . DMB-H requires several features compared to DMB-T.

First, it must consume low power suitable for mobile phones.

Second, high reception sensitivity must be guaranteed in a high speed mobile environment.

Third, the signal must be received with a simple and small antenna.

The Chinese TDS-OFDM transmission channel is a wireless mobile reception channel environment, and a mobile receiver employing a DMB-H single chip demodulator requires high-speed mobile reception, resulting in a Doppler shift in the received signal spectrum. . Therefore, bit error rate (BER) and carrier-to-noise ratio (BER) in a mobile receive multipath channel environment only by error correction using a channel coding scheme of MPE-FEC (MultiProtocol Encapsulation-Forward Error Correction) C / N: Carrier-to-Noise ratio (C / N) There is a problem that cannot fully satisfy the critical performance.

SUMMARY OF THE INVENTION The present invention has been made in an effort to provide a digital multimedia broadcasting reception apparatus and method capable of reducing degradation of reception performance in a channel environment in which a Doppler transition of a reception signal spectrum occurs.

In accordance with another aspect of the present invention, there is provided a digital multimedia broadcasting reception apparatus comprising: first and second tuners for receiving a digital multimedia broadcasting wireless signal and converting the first and second baseband signals into an operating power supply; Responsive to the first and second baseband signals and converting the first and second baseband signals into digital signals, respectively, and corresponding to the reception performance of the digital multimedia broadcasting wireless signal. It is preferably configured as a power supply for selectively supplying the operating power to at least one of the first and second analog / digital converters.

In accordance with another aspect of the present invention, there is provided a method for receiving a digital multimedia broadcasting according to the present invention, which is performed in the digital multimedia broadcasting receiving apparatus. If it is determined to be lower, it is preferred to provide the operating power to the first and second analog / digital converters.

Hereinafter, before explaining the present invention, the following describes the TDS-OFDM transmitter, the transmission frame of the signal transmitted from the TDS-OFDM transmitter, the DMB-T receiver, and the Chinese DMB-H receiver in order to help the understanding of the present invention. The same will be described with reference to the accompanying drawings.

FIG. 1 is a block diagram schematically illustrating a TDS-OFDM transmitter, including a transmission parameter signaling (TPS) generation unit 8, a channel coding unit 10, a modulation unit 11, Inverse Discrete Fourier Transform (IDFT) 12, PN Generator 13, Distribution (MUX) 14, Square Root Raised Cosine (SQRC) Filter 15, Mixer 16 and Antenna ( 18).

Referring to FIG. 1, the channel coding unit 10 performs channel coding, and the modulator 11 performs a bit stream using a channel coded result and a TPS input from the TPS generation unit 8. stream is modulated with one of 4/16 / 64-QAM (Quadrature Amplitude Modulation). The modulated signal is converted into a time domain signal at IDFT 12. The PN to be used as a training signal is generated by the PN generation unit 13. The distribution unit 14 distributes the PN generated from the PN generation unit 13 and the result converted by the IDFT 12 in the time domain, and outputs the distributed result to the SQRC filter 15. The SQRC filter 15 performs SQRC (α = 0.05) filtering to limit the bandwidth of the DMB-T signal. The mixer 16 multiplies the result filtered by the SQRC filter 15 with the center frequency fc and upconverts the RF band to the RF band, and transmits the converted result through the antenna 18.

2 is a diagram illustrating a structure of a transmission frame of a signal transmitted by a TDS-OFDM transmitter.

Referring to FIG. 2, a super frame group consists of a super frame, a super frame consists of a frame group, and a frame group consists of a signal frame. . The frame group header includes a frame sync unit and a frame body. The frame synchronizer consists of a PN sequence. For this purpose, the PN uses a sequence of m = 8. Since m = 8 has only 255 bit streams, the PN is extended with preambles and postambles to create a 1/9 guard interval. At this time, the preamble and the postamble are cyclic extensions of the PN. The definition of the PN sequence is shown in Equation 1 below.

In the PN sequence, the generated phase changes from 0 to 254 according to the initial state. The frame body consists of the sum of the data 3734 and the TPS 36, and the TPS is composed of 9-symbol groups, as shown in FIG. 2 in the 3780 frame body section. At this time, the TPS is quadrature phase shift keying (QPSK) modulation.

3 is a conceptual block diagram of a DMB-T receiver including an antenna 19, a tuner 20, an automatic gain controller (AGC) 21, and an analog / digital converter (A / D). Converter (22), Phase Splitter (23), Mixer (24), Re-Sampler (25), SQRC Filter (26), PN Correlator (27), Synchronization Unit 28, tracking unit 29, frequency error compensator 30, discrete Fourier transform units (DTFs) 31-1 and 31-2, and channel equalizer (32). It consists of.

Referring to FIG. 3, an ultra-high frequency (UHF) signal received through an antenna 19 is converted into a baseband signal by the tuner 20. Here, the UHF signal is, for example, 474 MHz to 858 MHz. The AGC 21 normalizes the power of the baseband signal and outputs the normalized result to the ADC 22. The ADC 22 converts the normalized analog form signal into a digital signal. The phase divider 23 divides the digital signal into in-phase and quadrature signals. The mixer 24 compensates the estimated frequency error by using the automatic frequency controller (AFC) in the frequency error compensator 30 for the divided signal. At this time, the compensated result is sampled again in the resampler 25 and then filtered in the SQRC filter 26 as in the transmitter. The synchronization unit is largely composed of a frequency error compensation unit 30 for compensating for a frequency error, a synchronization unit 28 for synchronizing a PN sequence sent by a transmitter, and a tracking unit 29 for compensating for a symbol error. The frequency error compensator 30, the synchronizer 28, and the tracking unit 29 all perform operations using the PN correlator 29.

As described above, the result synchronized in the synchronizer is inverse discrete Fourier transformed in the DFTs 31-1 and 31-2, and finally channel compensated in the channel compensator 32 to the channel decoder (not shown). Output

Channel compensation is inverse filtering of the estimated channel, which takes place in the frequency domain. Because it is in the frequency domain, it is implemented as a single tap. A single tap can be implemented because each subchannel in the frequency domain is modeled with flat fading.

4 is a conceptual block diagram of a Chinese DMB-H receiver, which is composed of a DMB-T demodulator 40, a time slicing unit 42, and an MPE-FEC 44.

The DMB-T demodulator 40 shown in FIG. 4 operates in the same manner as the DMB-T receiver shown in FIG. 3 by inputting a radio input signal (RF input). That is, the DMB-T demodulator 40 may perform the same configuration and role as the DMB-T receiver shown in FIG. 3. In the case of DMB-H, the time slicing unit 42 is used to minimize power consumption. That is, the time slicing unit 42 blocks power from being supplied to the DMB-T demodulator 40 during the off-time period in order to save power. The MPE-FEC 44 also serves as a kind of virtual time interleaving, and may add FEC to the encoder stage to robust the DMB-T data.

The service model considers various scalability of portable and mobile multimedia broadcasting such as Internet application, multicast / call service, portable mobile reception service, and the like.

In addition, the transmission channel of the Chinese-style DMB-H is a signal frequency network (SFN) employing a layered-multi-frame that is synchronized with delay time to provide reliable coverage for a certain service area. Mobile receive channel. In the case of the Chinese DMB-H transmission channel, not only the magnitude of the received signal is time-varying but also the Doppler transition of the received signal spectrum due to the influence of mobile reception. In this channel environment, TDS-OFDM method is adopted that combines time-based PN sequence and payload data in frequency domain to transmit and receive signals for fast code acquisition and reliable sync trace. A more robust and effective channel coding scheme is applied to correct BER and C / N threshold performance by correcting errors in transport channels.

Hereinafter, the configuration and operation of an embodiment of a digital multimedia broadcasting reception device according to the present invention will be described with reference to the accompanying drawings.

FIG. 5 is a block diagram of an embodiment of a digital multimedia broadcasting receiver according to the present invention, wherein the first and second tuners 60 and 62 and the first and second analog / digital converters (ADCs) are shown. 64 and 66, first and second Auto Gain Controls (AGC) 68 and 70, first and second low pass filters (LPFs) 72 and 74 , Performance tester 76, power supply 78, first, second, third, fourth, fifth, sixth, seventh and eighth capacitors C1, C2, C3, C4, C5, C6 , C7 and C8) and resistors R1 and R2.

The first tuner 60 shown in FIG. 5 receives the digital multimedia broadcasting radio signal, converts it into a first baseband signal, and outputs the converted first baseband signal to the first ADC 64. The second tuner 62 receives the digital multimedia broadcasting radio signal, converts it into a second baseband signal, and outputs the converted second baseband signal to the second ADC 66.

The first ADC 64 operates in response to an operating power supplied from the power supply 78, and includes a first baseband input from the first tuner 60 through the first and second capacitors C1 and C2. Convert the signal to a digital signal. Similarly, the second ADC 66 operates in response to the operating power supplied from the power supply 78, and inputs through the third and fourth capacitors C3 and C4 from the second tuner 62. 2 Convert the baseband signal into a digital signal.

According to the present invention, each of the first and second ADCs 64 and 66 may be implemented to have a sampling clock frequency of 30.4 MHz and a resolution of 10 bits.

The power supply unit 78 selectively supplies operating power to at least one of the first and second analog / digital conversion units 64 and 66 corresponding to the reception performance of the digital multimedia broadcasting wireless signal input from the performance inspecting unit 76. do. That is, when the operating power is supplied to the first analog / digital converter 64 and the operating power is not supplied to the second analog / digital converter 66, the power supply unit 78 may not perform well. ) May also supply operating power to the second analog / digital converter 66.

In addition, while the operating power is supplied to both the first and second analog / digital converters 64 and 66, the operating power to the first or second analog / digital converter 64 or 66 in correspondence with the reception performance. Supply can be cut off. That is, when operating power is supplied to the first and second analog / digital converters 64 and 66, the checked reception performance is analyzed, and the first and second analog / digital converters 64 and 66 are analyzed. If it is determined that the reception performance is good even if only one of the operating power is supplied, the supply of the operating power to the first or second analog / digital converter 64 or 66 is cut off.

The digital multimedia broadcasting receiver shown in FIG. 5 may further include first and second automatic gain adjusters 68 and 70. In this case, the first automatic gain adjuster 68 normalizes the power of the result converted by the first analog / digital converter 64 and outputs the normalized result. Similarly, the second automatic gain adjuster 70 normalizes the power of the result converted by the second analog / digital converter 66 and outputs the normalized result.

The above-described digital multimedia broadcasting reception apparatus according to the present invention shown in FIG. 5 may be a Chinese digital multimedia (DMB) -H receiver. In this case, the tuner 60 shown in FIG. 5 plays the same role as the tuner 20 shown in FIG. 3, and the first and second ADCs 64 and 66 each have the A / A shown in FIG. 3. It plays the same role as D (22). However, in FIG. 3, the ADC 22 outputs the result output from the AGC 21, whereas in FIG. 5, the first and second ADCs 64 and 66 output the first and second results. Inputs are made to AGCs 68 and 70, respectively.

However, the present invention is not limited thereto, but the first and second baseband signals output from the first and second tuners 60 and 62 are different from the first and second AGCs 68 as shown in FIG. 5. And 70), respectively. In this case, the first and second AGCs 68 and 70 normalize the power of the first and second baseband signals and output the normalized result to the first and second ADCs 64 and 66, respectively. Can be. The first and second ADCs 64 and 66 convert the normalized result output from the first and second AGCs 68 and 70 into digital form.

The digital multimedia broadcasting receiver shown in FIG. 5 may further include first and second low pass filters 72 and 74. In this case, the first low pass filter 72 low pass filters the normalized results output from the first automatic gain adjuster 68 and outputs the low pass filtered results to the first tuner 60. Similarly, the second low pass filter 74 low pass filters the normalized results output from the second automatic gain adjuster 70 and outputs the low pass filtered results to the second tuner 62.

In this case, the first tuner 60 adjusts the level of the first baseband signal according to the low pass filtered result of the first low pass filter 72, and adjusts the first baseband signal having the adjusted level. 1 Output to ADC64. Similarly, the second tuner 62 adjusts the level of the second baseband signal corresponding to the low pass filtered result in the second low pass filter 74 and removes the second baseband signal having the adjusted level. 2 Output to ADC 66.

The performance tester 76 shown in FIG. 5 checks the reception performance of the digital multimedia broadcasting receiver, and outputs the checked reception performance to the power supply 78. To this end, the performance inspection unit 76 may receive the reception quality of the digital multimedia broadcasting receiver in the single antenna reception mode, the reception sensitivity when the antenna diversity reception mode is converted from the antenna diversity reception mode, and the single antenna reception mode. At least one of the reception sensitivity, the reception power of the reception device, and the bit error rates when switching to the antenna diversity reception mode can be checked as reception performance.

Here, the single antenna reception mode refers to a situation in which the operating power is supplied to only one of the first and second analog / digital converters 64 and 66. The antenna diversity reception mode refers to a situation in which operating power is supplied to the first and second analog / digital conversion units 64 and 66.

According to the present invention, the performance inspection unit 76 is a first register (not shown) that stores the reception sensitivity of the digital multimedia broadcasting reception device in the single antenna reception mode, when converting from the antenna diversity reception mode to the single antenna reception mode. A second register (not shown) that stores the reception sensitivity of the second register, a third register (not shown) that stores the reception sensitivity when switching from the single antenna reception mode to the antenna diversity reception mode, and the reception power of the reception device. And a fourth register (not shown) that stores at least one of the bit error rates as a reception capability.

Alternatively, the information stored in the first to third registers may be stored in only one register. For example, when the information stored in the first to third registers are stored in the 12-bit register, the reception sensitivity of the digital multimedia broadcasting receiver in the single antenna reception mode is stored from bit 0 to bit 2, and the antenna diver Receive sensitivity is stored from bit 4 to bit 6 when switching from the 30 receive mode to the single antenna receive mode, and receive sensitivity is stored from bit 8 to bit 10 when switching from the single antenna receive mode to the antenna diversity receive mode. do.

Hereinafter, an embodiment of a digital multimedia broadcasting reception method according to the present invention will be described with reference to the accompanying drawings.

FIG. 6 is a flowchart for explaining an embodiment of a digital multimedia broadcasting reception method according to the present invention, and includes differently supplying operating power according to reception performance (90th through 94th steps).

The digital multimedia broadcasting receiving method according to the present invention shown in FIG. 6 may be performed in the digital multimedia broadcasting receiving apparatus shown in FIG. 1.

First, it is determined whether the reception performance of the DMB receiving apparatus is lower than the threshold performance in a situation where only one of the first and second ADCs 64 and 66 is supplied with operating power (step 90). To this end, the reception performance is inspected by the performance inspector 76 shown in FIG. 5, and the 90th step may be performed by the power supply 78. Here, the threshold performance means the minimum reception performance that the receiving device should have as the reception performance desired by the user, and may be preset in advance or may be changed later by the user. In this case, the reception performance may be only the reception sensitivity of the digital multimedia broadcasting reception device, and at least one of reception sensitivity and reception power and bit error rates of the reception device when switching from the single antenna reception mode to the antenna diversity reception mode is determined. It may further include.

If it is determined that the reception performance of the DMB receiving apparatus is lower than the threshold performance in a situation where only one of the first and second ADCs 64 and 66 is supplied with operating power, the power supply unit 78 may determine the first and second ADCs. Operational power is supplied to both analog / digital converters 64 and 66 (step 92). However, if it is determined that the reception performance of the DMB receiving apparatus is not lower than the threshold performance in a situation where only one of the first and second ADCs 64 and 66 is supplied with operating power, the power supply unit 78 may have only one side. A situation in which operating power is supplied is maintained (step 94).

After the operation 92, that is, when the operating power is supplied to both the first and second ADCs 64 and 66, the reception performance may be good even if only the first or second ADC 64 or 66 is supplied. If determined, only one of the first and second analog / digital converters 64 and 66 supplies operating power. To this end, the reception performance used by the power supply unit 78 may further include at least one of the reception sensitivity and the reception power and bit error rates of the reception device when switching from the antenna diversity reception mode to the single antenna reception mode. .

According to the present invention, the above-described receiving method shown in FIG. 6 may be performed in the power supply unit 78 as follows.

The reception method according to the present invention shown in FIG. 6 may be selectively performed. That is, it is assumed that a mode bit indicating whether to operate the receiving device in the single antenna reception mode or the automatic mode regardless of the reception performance is set by the user.

If the power supply 78 recognizes that the mode bit indicates the single antenna reception mode, the power supply 78 supplies the operating power to only one of the first and second ADCs 64 and 66. In this case, for example, the operating power may be supplied only to the first ADC 64 and the operating power may not be supplied to the second ADC 66. On the contrary, the operating power may be supplied only to the second ADC 64 and the operating power may not be supplied to the first ADC 64. When power is initially supplied to the reception device shown in FIG. 5, the reception device may operate in a single antenna reception mode.

If the mode bit is recognized by the power supply unit 78 to indicate an automatic mode, the operating power source may be operated with at least one of the first and second ADCs 64 and 66 according to the reception performance of the receiving device as shown in FIG. 6. Is selectively supplied (90th through 94th steps). Here, the mode bit may be stored in a fifth register (not shown), and the fifth register may be embedded in the performance check unit 76 or the power supply unit 78.

The aforementioned first ADC 64 shown in FIG. 5 is connected to a resistor R1, fifth and sixth capacitors C5 and C6, and the second ADC 66 is connected to a resistor R2, seventh and Are connected to the eighth capacitors C7 and C8. Each of the resistors R1 and R2 may be implemented with a variable resistor.

According to the present invention, a part of the receiving device shown in FIG. 5 may be implemented as a single chip 80. The digital multimedia broadcasting receiver according to the present invention shown in FIG. 5 shows only the tuners 60 and 62, the ADCs 64 and 66 and the AGCs 68 and 70 for convenience of understanding the present invention. Although parts other than these are not shown, the parts 23 to 32 shown in the receiving device shown in FIG. 3 may be additionally provided in the device shown in FIG. 5.

As described above, since the digital multimedia broadcasting reception apparatus and method according to the present invention can switch from the single antenna reception mode to the antenna diversity reception mode according to the reception performance, the mobile multi-path channel is a mobile multi-path channel. Improves the margin of the system by enabling the stable data reception and the stable data reception by improving the bit error rate and C / N threshold performance of the receiver even in the environment of interference, fading, and noise, that is, poor reception performance. And, depending on the reception performance, it uses two tutors and two analog / digital converters while switching from the antenna diversity reception mode to a single antenna reception mode, and in some cases only one tuner and one analog / digital converter are used. You can also minimize power consumption. Has the effect.

Claims (9)

First and second tuners for receiving a digital signal for digital multimedia broadcasting and converting the first and second baseband signals; First and second analog / digital converters which operate in response to an operating power source and convert the first and second baseband signals into digital signals; First and second automatic gain adjusters for normalizing the power of the result converted by the first and second analog / digital converters and outputting the normalized result to the first and second tuners; First and second low pass filters for low pass filtering the normalized results output from the first and second automatic gain adjusters and for outputting a low pass filtered result to the first and second tuners; A power supply unit selectively supplying the operating power to at least one of the first and second analog / digital converters in accordance with the reception performance of the digital multimedia broadcasting wireless signal; And And a performance checker for checking the reception performance of the digital multimedia broadcasting radio signal and outputting the checked reception performance to the power supply unit. The method of claim 1, wherein the power supply unit While the operating power is supplied to the first and second analog / digital converters, the supply of the operating power to the first or second analog / digital converter is cut off in correspondence to the reception performance. Digital multimedia broadcasting reception device. The digital multimedia broadcasting receiver as claimed in claim 1, wherein the digital multimedia broadcasting receiver is a Chinese digital multimedia (DMB) -H receiver. According to claim 1, And the first and second tuners adjust the levels of the first and second baseband signals, respectively, in accordance with low pass filtered results. delete delete The method of claim 1, wherein the performance test unit Receiving sensitivity of the digital multimedia broadcasting receiver in the single antenna reception mode for supplying the operation power to only one of the first and second analog / digital converters, and operating the first and second analog / digital converters. A reception sensitivity when switching from a powered antenna diversity reception mode to the single antenna reception mode, a reception sensitivity when switching from the single antenna reception mode to the antenna diversity reception mode, a reception power of the reception device, and And checking at least one of bit error rates as the reception performance. The digital multimedia broadcasting receiving method performed by the digital multimedia broadcasting receiving apparatus according to claim 1, Receiving a wireless signal for digital multimedia broadcasting and checking a reception performance of the wireless signal; Determining whether the checked reception performance is lower than a threshold performance; And And if the reception performance is determined to be lower than the threshold performance, supplying the operating power to each of the first and second analog / digital converters. The method of claim 8, wherein the digital multimedia broadcasting receiving method And if the reception performance is determined to be higher than the threshold performance, supplying the operating power to only one of the first and second analog / digital converters.

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