EP2313984A2

EP2313984A2 - Apparatus for transmitting and receiving digital multimedia broadcasting and method thereof

Info

Publication number: EP2313984A2
Application number: EP09773702A
Authority: EP
Inventors: Jong Soo Lim; Young Su Kim; Kyu Tae Yang; Jae Hwui Bae; Byungjun Bae; Kwang-Yong Kim; Joungil Yun; Seomee Choi; Ji Bong Lee; Soo In Lee; Seungku Hwang; Chieteuk Ahn
Original assignee: Electronics and Telecommunications Research Institute ETRI
Current assignee: Electronics and Telecommunications Research Institute ETRI
Priority date: 2008-06-30
Filing date: 2009-06-30
Publication date: 2011-04-27
Also published as: KR20100003206A; WO2010002166A3; WO2010002166A2

Abstract

The present invention provides a digital multimedia broadcasting transmitting apparatus, including: a pilot signal generator that is used in estimating a transmission channel in a receiving apparatus and generates a pilot signal including at least one information a; a subcarrier mapping unit that maps the pilot signal to a subcarrier corresponding thereto; and a modulating unit that modulates an output of the subcarrier mapping unit, wherein the pilot signal has a value for specific information rather than a predetermined value in the receiving apparatus.

Description

APPARATUS FOR TRANSMITTING AND RECEIVING DIGITAL MULTIMEDIA BROADCASTING AND METHOD THEREOF

The present invention relates to an apparatus for transmitting and receiving digital multimedia broadcasting and a method thereof.

In a digital multimedia broadcasting system, a transmitting apparatus inserts a pilot signal having a predetermined value for each predetermined subcarrier unit into one symbol, and modulates a data signal and the inserted pilot signal, thereby transmitting them to a receiving apparatus.

The receiving apparatus demodulates the received signals and comprehends information that is distorted while the subcarrier into which the pilot signal is inserted is passing through a channel, thereby estimating a transmission channel using them. Thereafter, the receiving apparatus equalizes and outputs a data signal based on the estimated channel information.

At this time, the pilot signal has a predetermined value between the transmitting apparatus and the receiving apparatus, and is used only for estimating a channel, not including other information. Therefore, a problem arises in that a data rate is reduced by a ratio of the pilot that is inserted.

The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.

A technical object of an exemplary embodiment of the present invention is to provide an apparatus for transmitting and receiving digital multimedia broadcasting and a method thereof in which a pilot signal used in estimating a channel includes specific information.

In order to accomplish the object, an exemplary embodiment of the present invention provides a digital multimedia broadcasting transmitting apparatus, including: a pilot signal generator that is used in estimating a transmission channel in a receiving apparatus and generates a pilot signal including at least one information set; a subcarrier mapping unit that maps the pilot signal to a subcarrier corresponding thereto; and a modulating unit that modulates an output of the subcarrier mapping unit, wherein the pilot signal has a value for specific information rather than a predetermined value in the receiving apparatus.

Another embodiment of the present invention provides a digital multimedia broadcasting method of a digital multimedia broadcasting apparatus, including: generating a pilot signal that is used in estimating a transmission channel in a receiving apparatus and includes at least one information set; mapping a data signal and the pilot signal to a subcarrier corresponding to an OFDM symbol; modulating the mapped OFDM symbol; and transmitting the modulated OFDM symbol.

Yet another embodiment of the present invention provides a digital multimedia broadcasting receiving apparatus, including: a demodulating unit that demodulates a received signal; a pilot signal determination unit that determines a pilot signal from an output of the demodulating unit and extracts at least one information set included in the pilot signal; a channel estimating unit that estimates a transmission channel from the determined pilot signal; and an equalizer that equalizes a data signal of the output of the demodulating unit based on the estimated transmission channel.

Yet another embodiment of the present invention provides a digital multimedia broadcasting receiving method of a digital multimedia broadcasting receiving apparatus, including: demodulating a received signal; determining a pilot signal from the demodulated signal; extracting at least one information set included in the pilot signal; and estimating a transmission channel from the pilot signal and equalizing a data signal from the demodulated signal based on the estimated transmission channel.

According to the embodiments of the present invention, in the apparatus for transmitting and receiving digital multimedia broadcasting and a method thereof, the pilot signal used in estimating the channel includes specific information, making it possible to enhance the data rate.

FIG. 1 is a concept diagram of a digital multimedia broadcasting transmitting apparatus according to an exemplary embodiment of the present invention.

FIG. 2 is a concept diagram of a pilot signal generator 120 according to an exemplary embodiment of the present invention.

FIG. 3 is a diagram explaining an operation of a mapper 124 according to an exemplary embodiment of the present invention.

FIGS. 4 and 5 are diagrams explaining an operation of a subcarrier mapping unit 130 according to an exemplary embodiment of the present invention.

FIG. 6 is a concept diagram showing a digital multimedia broadcasting receiving apparatus according to an exemplary embodiment of the present invention.

FIG. 7 is a concept diagram showing a pilot signal determination unit 230 according to an exemplary embodiment of the present invention.

FIG. 8 is a concept diagram explaining operations of a correlation unit 231 and a determination unit 232 according to an exemplary embodiment of the present invention.

FIG. 9 is a diagram explaining an operation of a demapper 233 according to an exemplary embodiment of the present invention.

In the following detailed description, only certain exemplary embodiments of the present invention have been shown and described, simply by way of illustration. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. Accordingly, the drawings and description are to be regarded as illustrative in nature and not restrictive. Like reference numerals designate like elements throughout the specification.

In the specification, unless explicitly described to the contrary, the word "comprise" and variations such as "comprises" or "comprising" will be understood to imply the inclusion of stated elements but not the exclusion of any other elements.

Herein, an apparatus for transmitting and receiving digital multimedia broadcasting and a method thereof according to an exemplary embodiment of the present invention will be described in detail with reference to the accompanying drawings.

Referring to FIG. 1, a digital multimedia broadcasting transmitting apparatus 100 according to an exemplary embodiment of the present invention is configured to include a data processing unit 110, a pilot signal generator 120, a subcarrier mapping unit 130, a modulating unit 140, and an antenna 150.

The data processing unit 110 performs encoding on a data signal to be output based on one or more coding scheme, performs interleaving thereon, and maps it to a symbol, thereby outputting it to the subcarrier mapping unit 130.

The pilot signal generator 120 performs encoding on a specific information signal to be input based on one or more coding scheme, performs interleaving thereon, and maps it to a symbol, thereby generating a pilot signal used in estimating a channel in a receiving apparatus. Thereafter, the pilot signal generator 120 outputs the generated pilot signal to the subcarrier mapping unit 130.

At this time, the specific information included in the pilot signal may be various information required in demodulating signals received by the receiving apparatus, such as transmission parameter information, disaster broadcasting information, etc.

In other words, the pilot signal generated from the pilot signal generator 120 is used in estimating a channel having a value for specific information rather than a predetermined value in the receiving apparatus.

The subcarrier mapping unit 130 maps the signal output from the data processing unit 110 and the pilot signal generator 120 to the subcarrier.

The modulating unit 140 modulates the signal output from the subcarrier mapping unit 130.

The antenna 150 transmits the signal modulated in the modulating unit 140.

Referring to FIG. 2, the pilot signal generator 120 according to an exemplary embodiment of the present invention is configured to include a scrambler 121, an encoder 122, an interleaver 123, and a mapper 124.

The scrambler 121 performs energy dispersion on the specific information signal to be input using a dispersion polynomial.

The encoder 122 performs encoding on the specific information signal whose energy is dispersed in the scrambler 121 to have a strong error correction function against a radio channel. At this time, a Read-Solomon (RS) code, a convolution code, a low density parity check (LDPC) code, a turbo code, etc., may be used as the encoding scheme.

The interleaver 123 performs interleaving on the signal output from the encoder 122 in order to disperse errors in fading the radio channel.

The mapper 124 maps the signal output from the interleaver 123 to a transmission symbol. At this time, binary phase shift keying (BPSK), quadrature phase shift keying (QPSK), multi-phase shift keying (M-PSK), multi-quadrature amplitude modulation (M-QAM), Walsh code, etc., may be used as the mapping scheme.

Meanwhile, at least one of the scrambler 121 and the interleaver 123 may be omitted from the pilot signal generator 120.

FIG. 3 shows a case where the mapper 124 generates pilot signals by mapping specific information signals having 2-bit output from an interleaver 123 to Walsh codes (, , , ) that are orthogonal to each other.

Referring to FIG. 3, the specific information signa '00' is mapped to '1 1 1 1' corresponding to the Walsh code (), the specific information signal '01' is mapped to '1 -1 1 -1' corresponding to the Walsh code (), the specific information signal '10' is mapped to '1 1 -1 -1' corresponding to the Walsh code (), and the specific information signal '11' is mapped to '1 -1 -1 1' corresponding to the Walsh code ().

At this time, the Walsh codes mapped for the specific information signals become the pilot signals.

As described above, when a transmitting apparatus generates the pilot signals using the Walsh codes that are orthogonal to each other, a receiving apparatus may determine the pilot signals and enhance accuracy in extracting the specific information signals included in the pilot signals.

FIGS. 4 and 5 are diagrams explaining an operation of a subcarrier mapping unit 130 according to an exemplary embodiment of the present invention. FIG. 4 is a diagram showing a shape where the pilot signals are inserted into one orthogonal frequency division multiplexing (OFDM) symbol, and FIG. 5 is a diagram showing a shape where the pilot signals are inserted into the entire OFDM symbols.

Referring to FIG. 4, a subcarrier mapping unit 130 inserts each element of a Walsh code corresponding to a pilot signal one by one for each predetermined subcarrier unit in the OFDM symbol and for each eight subcarriers in the case of FIG. 4. For example, when the specific information signal is '10' , each of '1 1 -1 -1' (Walsh code ()) that is the pilot signal corresponding to '10' is inserted one by one.

More specifically, the subcarrier mapping unit 130 inserts 1 that is a second value of the Walsh code () into an eighth subcarrier from a subcarrier into which 1 that is a first value of the Walsh code () is inserted, inserts '-1' that is a third value of the Walsh code () into the eighth subcarrier, and inserts '1' that is the last value of the Walsh code () into the eighth subcarrier.

Thereafter, in the same manner, '1 1 -1 -1' (Walsh code ()) that is the pilot signal corresponding to the specific information signal '10' is inserted repeatedly into each eighth subcarrier.

Referring to FIG. 5, the pilot signal in the specific symbol is inserted into a fourth subcarrier from a subcarrier into which the pilot signal is inserted in a previous symbol, and the pilot signals may be inserted into the entire symbols in the same manner. In addition, data signals may be inserted into another subcarrier into which the pilot signals are not allocated.

Hereinafter, an apparatus for transmitting and receiving digital multimedia broadcasting and a method thereof according to an exemplary embodiment of the present invention will be described in detail with reference to the accompanying drawings.

Referring to FIG. 6, a digital multimedia broadcasting receiving apparatus 200 according to an exemplary embodiment of the present invention is configured to include an antenna 210, a demodulating unit 220, a pilot signal determination unit 230, a channel estimating unit 240, an equalizer 250, and a data processing unit 260.

The antenna 210 outputs a signal received from a digital multimedia broadcasting transmitting apparatus 100 to the demodulating unit 220.

The demodulating unit 220 demodulates an output of the antenna 210.

The pilot signal determination unit 230 receives values of a subcarrier into which a pilot signal is inserted from the output of the demodulating unit 220, and determines the pilot signal based on the correlations between the received pilot signals and Walsh codes (, , , ). Thereafter, the pilot signal determination unit 230 outputs specific information signal included in the pilot signal based on the determined pilot signal.

The channel estimating unit 240 estimates a transmission channel based on the pilot signal determined by the pilot signal determination unit 230 and the signal demodulated by the demodulating unit 220. More specifically, a signal of the subcarrier into which the pilot is inserted, among the signals demodulated by the demodulating unit 220, is compared with the pilot signal determined by the pilot signal determination unit 230, thereby estimating a transmission channel based on the distorted degree thereof.

The equalizer 250 equalizes and outputs a data signal based on the channel information estimated by the channel estimating unit 240.

The data processing unit 260 performs and outputs symbol demapping, deinterleaving, channel decoding, etc., on the data signal equalized by the equalizer 250.

Referring to FIG. 7, a pilot signal determination unit 230 according to an exemplary embodiment of the present invention is configured to include a correlation unit 231, a determination unit 232, a demapper 233, a deinterleaver 234, a decoder 235, and a descrambler 236.

The correlation unit 231 receives values of a subcarrier into which pilot signals are inserted from an output of the demodulating unit 220, and obtains correlations between the received pilot signals and each of Walsh codes

The determination unit 232 integrates the correlations obtained by the correlation unit 231 by the frequency that the pilot signals are repeatedly inserted into one symbol, thereby determining the Walsh code having the largest correlation as a pilot signal. Thereafter, the determination unit 232 outputs the determined pilot signal to the demapper 233 and the channel estimating unit 240.

The demapper 233 demaps the pilot signal in a Walsh code shape determined by the determination unit 232, thereby comprehending a specific information signal included in the pilot signal.

The deinterleaver 234 performs deinterleaving on the output of the demapper 233.

The decoder 235 performs decoding on the output of the deinterleaver 234.

The descrambler 236 performs descrambling on the output of the decoder 235, thereby outputting a specific information signal.

Meanwhile, at least one of the deinterleaver 234 and the descrambler 236 may be omitted from the pilot signal determination unit 230.

As shown in FIG. 8, a pilot signal determination unit obtains correlations between signals of a subcarrier into which a pilot signal is inserted and each of Walsh codes (, , , ), thereby determining a Walsh code having the highest correlation as a pilot signal.

In addition, correlation between the signals of the subcarrier into which the pilot signal is inserted, among the signals of the subcarrier that are repeatedly transmitted, and each of the Walsh codes (, , , ) is obtained each time and is integrated, making it possible to improve accuracy in determining the pilot signal.

FIG. 9 is a diagram explaining an operation of a demapper 233 according to an exemplary embodiment of the present invention. Referring to FIG. 9, a pilot signal determined as '1 1 1 1' corresponding to the Walsh code () is demapped to a specific information signal '00', a pilot signal determined as '1 -1 1 -1' corresponding to the Walsh code () is demapped to a specific information signal '01', a pilot signal determined as '1 1 -1 -1' corresponding to the Walsh code () is demapped to a specific information signal '10' and a pilot signal determined as '1 -1 -1 1' corresponding to the Walsh code () is demapped to a specific information signal '11'.

According to an exemplary embodiment of the present invention, the pilot signal used in estimating the channel includes specific information, making it possible to improve the data rate.

The above-mentioned exemplary embodiments of the present invention are not embodied only by a method and apparatus. Alternatively, the above-mentioned exemplary embodiments may be embodied by a program performing functions that correspond to the configuration of the exemplary embodiments of the present invention, or a recording medium on which the program is recorded. These embodiments can be easily devised from the description of the above-mentioned exemplary embodiments by those skilled in the art to which the present invention pertains.

While this invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

Claims

A digital multimedia broadcasting transmitting apparatus, comprising:

a pilot signal generator that is used in estimating a transmission channel in a receiving apparatus and generates a pilot signal including at least one information set;

a subcarrier mapping unit that maps the pilot signal to a subcarrier corresponding thereto; and

a modulating unit that modulates an output of the subcarrier mapping unit,

wherein the pilot signal has a value for specific information rather than a predetermined value in the receiving apparatus.
The digital multimedia broadcasting transmitting apparatus of claim 1, wherein the pilot signal generator includes a mapper that maps the at least one information set to a symbol to generate a pilot signal.
The digital multimedia broadcasting transmitting apparatus of claim 2, wherein the transmission symbol includes Walsh codes.
The digital multimedia broadcasting transmitting apparatus of claim 2, wherein the pilot signal generator further includes an encoder that performs encoding on the at least one information set before the at least one information set is mapped to the transmission symbol.
The digital multimedia broadcasting transmitting apparatus of claim 1, wherein the subcarrier mapping unit repeatedly maps the same pilot signal to one OFDM symbol.
The digital multimedia broadcasting transmitting apparatus of claim 1, wherein the at least one information set includes at least one of a transmission parameter for demodulating the signal received in the receiving apparatus and disaster broadcasting information.
A digital multimedia broadcasting method of a digital multimedia broadcasting apparatus, comprising:

generating a pilot signal that is used in estimating a transmission channel in a receiving apparatus and includes at least one information set;

mapping a data signal and the pilot signal to a subcarrier corresponding to an OFDM symbol;

modulating the mapped OFDM symbol; and

transmitting the modulated OFDM symbol.
The digital multimedia broadcasting method of claim 7, wherein the generating the pilot signal includes mapping the at least one information set to a transmission symbol to generated the pilot signal.
The digital multimedia broadcasting method of claim 7, wherein the at least one information set includes at least one of a transmission parameter for demodulating the signal received in the receiving apparatus and disaster broadcasting information.
A digital multimedia broadcasting receiving apparatus, comprising:

a demodulating unit that demodulates a received signal;

a pilot signal determination unit that determines a pilot signal from an output of the demodulating unit and extracts at least one information set included in the pilot signal;

a channel estimating unit that estimates a transmission channel from the determined pilot signal; and

an equalizer that equalizes a data signal of the output of the demodulating unit based on the estimated transmission channel.
The digital multimedia broadcasting receiving apparatus of claim 10, wherein the pilot signal determination unit determines a code having the largest correlation among correlations between values of a subcarrier into which the pilot signal is inserted and a plurality of codes as the pilot signal.
The digital multimedia broadcasting receiving apparatus of claim 11, wherein the pilot signal is repeatedly inserted into one OFDM symbol.
The digital multimedia broadcasting receiving apparatus of claim 12, wherein the pilot signal determination unit includes:

a correlation unit that calculates correlations between values of the subcarrier and the plurality of codes; and

a determination unit that determines a code corresponding to the largest value among values integrated by the frequency with which the pilot signal is repeatedly inserted into the OFDM symbol as a pilot signal in the correlations.
The digital multimedia broadcasting receiving apparatus of claim 10, wherein the pilot signal determination unit further includes a demapper that demaps the determined pilot signal to extract the at least one information set included in the pilot signal.
The digital multimedia broadcasting receiving apparatus of claim 10, wherein the at least one information set includes at least one of a transmission parameter for demodulating the received signal and disaster broadcasting information.
A digital multimedia broadcasting receiving method of a digital multimedia broadcasting receiving apparatus, comprising:

demodulating a received signal;

determining a pilot signal from the demodulated signal;

extracting at least one information a included in the pilot signal; and

estimating a transmission channel from the pilot signal and equalizing a data signal from the demodulated signal based on the estimated transmission channel.
The digital multimedia broadcasting receiving method of claim 16, wherein the determining the pilot signal comprises determining a code having the largest correlation among correlations between values of a subcarrier into which the pilot signal is inserted and a plurality of codes as the pilot signal.
The digital multimedia broadcasting receiving method of claim 17, wherein the pilot signal is repeatedly inserted into one OFDM symbol.
The digital multimedia broadcasting receiving method of claim 16, wherein the determining the pilot signal includes:

calculating correlations between values of the carrier and the plurality of codes; and

determining a code corresponding to the largest value among integrated values by the frequency with which the pilot signal is repeatedly inserted into the OFDM symbol as a value of a pilot signal.
The digital multimedia broadcasting receiving method of claim 16, wherein the at least one information a includes at least one of a transmission parameter for demodulating the received signal and disaster broadcasting information in the correlation.