KR100243649B1 - Wideband mobile multimedia transmitter and receiver - Google Patents

Abstract

1. TECHNICAL FIELD OF THE INVENTION

The present invention relates to a broadband mobile multimedia transceiver.

2. The technical problem to be solved by the invention

Disclosure of Invention The present invention provides a broadband mobile multimedia transceiver for transmitting voice, data, and video at high speed using a variable channel, unlike a conventional mobile communication system.

3. Summary of Solution to Invention

The present invention provides the advantages of Orthogonal Frequency Division Multiplexing (OFDM) resistant to internal symbol interference (ISI) and the frequency diversity effect of Direct Sequence Sequence Division Multiple Access (DS-CDMA). Voice, data and video can be assigned to variable channels for high speed transmission.

4. Important uses of the invention

The present invention is used in a broadband mobile multimedia system.

Description

Broadband mobile multimedia transceiver

The present invention relates to a broadband mobile multimedia transceiver for transmitting all voice, data and video at high speed, unlike a conventional mobile communication system.

Future communication services will be in the form of wireless multimedia services that allow users to easily access various services while enjoying freedom of movement. A communication system for providing such a wireless multimedia service should be able to accommodate variable and high speed data, and be able to effectively share resources such as frequency, database, and devices required for calculation and storage. In addition, the technology to reduce the size and power consumption of the terminal, and to cope with the changing channel environment seems to have to be solved.

Direct-Sequence Spread Spectrum Code Division Multiple Access (DSSS-CDMA), a promising method in current mobile voice communications, transforms a narrowband flat fading environment into a wideband frequency selective environment. By providing a (RAKE) receiver, internal chip interference (ICI) can be reduced.

However, such a direct sequence spread spectrum code division multiple access (DSSS-CDMA) scheme has a problem in that it is difficult to implement as the complexity of the receiver increases proportionally as the transmission bandwidth increases. Therefore, it can be seen that this type of system is limited to a system for transmitting broadband data.

Orthogonal Frequency Division Multiplexing (OFDM), which has proven superior performance in current broadcasting systems, includes a serial / parallel converter, thereby making symbol length longer than delay spread to reduce internal symbol interference (ISI). Can be reduced.

However, such an OFDM scheme has a problem that frequency diversity is difficult to expect because each symbol uses a narrow band frequency using one carrier. Thus, OFDM systems require robust channel coding and frequency interleaving techniques.

In order to solve the above problems, the present invention can simultaneously take advantage of OFDM, which is resistant to internal symbol interference (ISI), and frequency diversity effect of direct sequence code division multiple access (DS-CDMA). And it is an object of the present invention to provide a wideband mobile multimedia transceiver that can be transmitted at high speed by assigning a video to a variable channel.

1 is a block diagram of an embodiment of a broadband mobile multimedia transmission apparatus according to the present invention.

2 is a block diagram of an embodiment of a broadband mobile multimedia receiving apparatus according to the present invention;

3 is a graph showing system performance when the bit precision of the matched filter is fixed to 4 bits.

* Explanation of symbols for the main parts of the drawings

11: convolutional encoder 12: QPSK mapping unit

13,14,18 Multiplier 15 Serial to Parallel Converter

16: 128 point complex inverted fast Fourier transformer (IFFT)

17: bottle / serial conversion and guard symbol insert

19: synthesizer

21: Serial / parallel conversion and guard section symbol detector

22: symbol and frame synchronization unit 23, 25: storage unit (SRAM)

24: 128 point OFDM demodulator (fast Fourier transformer)

26: bottle / serial converter 27: matching filter

28: QPSK demodulator

A transmission apparatus of the present invention for achieving the above object is a broadband mobile multimedia transmission apparatus for transmitting voice, data and video, comprising: encoding means for performing channel encoding by receiving transmission data from the outside; Mapping means for receiving data from an encoding means and performing four-phase phase modulation (QPSK) mapping; First multiplication means for receiving data from the mapping means and multiplying a pseudo noise (PN) code input from the outside; Second multiplication means for receiving data multiplied by the pseudo noise from the first multiplication means and multiplying a Walsh code input from the outside; Serial / parallel conversion means for receiving data from the second multiplication means and performing serial / parallel conversion; Inverted fast Fourier transform means for receiving data from the serial / parallel converting means and performing inverted fast Fourier transform (IFFT); Parallel / serial conversion and guard interval symbol insertion means for performing parallel / serial conversion and inserting a guard interval symbol by receiving modulation data from the inverted fast Fourier transform means; Third multiplication means for receiving data from the parallel / serial conversion and guard interval symbol inserting means and multiplying and modulating the high frequency (RF) input from the outside; And synthesizing means for receiving, synthesizing, and propagating modulation data from the third multiplication means.

In addition, the receiving apparatus of the present invention, in a broadband mobile multimedia receiving apparatus for receiving voice, data and video, for receiving the modulation data propagated from the transmitting apparatus to perform the serial / parallel conversion and to detect the guard interval symbol Serial / parallel conversion and guard interval symbol detection means; Symbol and frame synchronization means for acquiring symbol synchronization and frame synchronization by receiving data from the serial / parallel conversion and guard interval symbol detection means; First storage means for receiving and storing data from the symbol and frame synchronization means; First demodulation means for demodulating by receiving data from the first storage means and performing Fast Fourier Transform (FFT); Second storage means for receiving and storing demodulated data from the first demodulation means; Parallel / serial conversion means for receiving data from the second storage means and performing parallel / serial conversion to transmit data; Despreading means for receiving data from the parallel / serial conversion means and performing despreading; And second demodulation means for transmitting the reconstruction data to the outside after demodulating the despread data output from the despreading means.

Hereinafter, with reference to the accompanying drawings will be described an embodiment according to the present invention;

In general, to transmit video data using wireless communication, it must have a transmission speed of at least 64Kbps. In addition, to transmit high-quality video, it must have a transmission speed of at least 256Kbps. In order to meet these user requirements, a transmission / reception device capable of variably allocating a transmission channel of at least 256Kbps to 8Mbps is required.

Transmitter specifications that can variably allocate a transmission channel of at least 256Kbps to 8Mbps to the user are shown in Table 1 below.

TABLE 1

On the other hand, using a Walsh code of size 32 as shown in Table 2 below, it is possible to allocate a 256Kbps transmission channel to a maximum of 32 users. This utilizes the characteristic that the mutual interference between codes, which is a characteristic of Walsh codes, is '0'. In addition, a plurality of Walsh codes may be assigned to one user, thereby assigning a transmission channel up to 8Mbps. The length of the guard interval sensitive to the channel environment is 488 nsec, and the number of subcarriers is 128. Therefore, a 128-point inverse fast Fourier transform (IFFT) and a Fast Fourier transform (FFT) should be used.

TABLE 2

Next, the configuration of the apparatus for transmitting a broadband mobile multimedia will be described in detail with reference to FIG. 1.

1 is a configuration diagram of an embodiment of a broadband mobile multimedia transmission apparatus according to the present invention, in which "11" is a convolutional encoder having a constraint length of 7 and a coding rate of 1/2, and "12" is a four-phase phase modulation (QPSK). Quadrature Phase Shift Keying), "13,14,18" is a multiplier, "15" is a serial / parallel converter, "16" is a 128-point complex inverted fast Fourier transformer (IFFT), and "17" is The bottle / serial conversion and guard interval symbol inserter, “19”, respectively, represents a synthesizer.

As shown in the figure, the convolutional encoder 11 receives transmission data such as voice, data, video, etc. of 256 Kbps from the outside, performs channel encoding, and transmits 512 Ksps of data to the QPSK mapping unit 12.

The QPSK mapping unit 12 receives 512Ksps of data from the convolutional encoder 11 and performs QPSK mapping to transmit two 256Ksps of data to two first multipliers 13 one by one.

The two first multipliers 13 receive two 256Ksps of data from the QPSK mapping unit 12 one by one and multiply each 32 PN code having a length of 32 by input from the outside, and thus, the two second multipliers 14. Send one by one.

The two second multipliers 14 receive two data multiplied by pseudo noises from two first multipliers 13 and multiply each of Walsh codes having a length of 32 by serially to multiply the data of 8.192 MHz. Transfer to converter 15.

The serial / parallel converter 15 receives 8.192 MHz of data from two second multipliers 14 and performs serial / parallel conversion to convert 128 64 Ksps of data into a 128-point complex inverted fast Fourier transformer (IFFT) 16. To send.

The 128-point complex inverted fast Fourier transformer (IFFT) 16 receives 128 64 Ksps data from the serial / parallel converter 15 and performs inverted fast Fourier transform (IFFT) to convert the 128 64 Ksps modulated data into parallel and serial. The guard section is output to the symbol inserter 17.

The parallel / serial conversion and guard interval symbol inserter 17 receives 128 64Ksps modulation data from a 128-point complex inverted fast Fourier transformer (IFFT) 16 to perform parallel / serial conversion and insert a guard symbol during 488usec. To transmit two data to two third multipliers 18.

The two third multipliers 18 receive two data from the bottle / serial conversion and the guard interval symbol inserter 17 one by one, multiply and modulate the high frequency (RF) input from the outside, and transmit the modulated data to the synthesizer 19.

The synthesizer 19 receives two modulated data from two third multipliers 18 and synthesizes the synthesized data to propagate over the airwaves.

Next, the configuration of the broadband mobile multimedia receiving apparatus will be described in detail with reference to FIG. 2.

2 is a block diagram of an embodiment of a broadband mobile multimedia receiver according to an embodiment of the present invention, in which "21" is a serial / parallel conversion and guard interval symbol detector, "22" is a symbol and frame synchronizer, and "23,25". "24" denotes a storage unit (SRAM), "24" denotes a 128-point OFDM demodulator, "26" denotes a bottle / serial converter, "27" denotes a matching filter, and "28" denotes a QPSK demodulator.

The serial / parallel conversion and guard interval symbol detector 21 receives the modulation data propagated from the transmitting device, performs serial / parallel conversion, detects a guard interval symbol, and converts two 8-bit data into two symbols and a frame synchronizer ( 22).

The two symbol and frame synchronizers 22 receive two 8-bit data one by one from the serial / parallel conversion and the guard interval symbol detector 21 to obtain symbol synchronization and frame synchronization, and thus, two 8-bit data are divided into two symbols. 1 is transmitted to the storage unit 23.

The two first storage units 23 receive two 8-bit data from the two symbol and frame synchronizers 22 one by one, and the 128 result values of the 128-point complex inverted fast Fourier transformer (IFFT) 16 of the transmitting apparatus. After storing, the 128 results are transmitted to the 128-point OFDM demodulator 24 in order.

The 128-point OFDM demodulator 24 receives 128 result values from the two first storages 23 and performs fast Fourier transform and demodulates the opposite of the 128-point complex inverted fast Fourier transformer (IFFT) 16 of the transmitting apparatus. The data is transmitted to the two second storage units 25.

The two second storage units 25 receive two pieces of demodulated data one by one from the 128-point OFDM demodulator 24 and store four-bit data to two parallel / serial converters 26.

The two parallel / serial converters 26 receive 4-bit data from two second storage units 25 to perform parallel / serial conversion and transmit them one by one to two matching filters 27.

The two matched filters 27 receive 4-bit data from the two parallel / serial converters 26 and despread it, and transmit them to the Quadrature Phase Shift Keying (QPSK) demodulator 28.

The QPSK demodulator 28 determines whether the despread data values output from the two matched filters 27 are greater than or equal to '0' or more, and restores the data, and then the data is restored to the next external image signal processing stage. Send it.

At this time, the number of bits of the input value of the 128-point OFDM demodulator 24 uses 8 bits, and the number of bits of the input values of the two matching filters 27 uses 4 bits. As shown in FIG. 3, 8 bits and 4 bits are optimal for the number of bits of these input values.

The present invention described above is not limited to the above-described embodiments and the accompanying drawings, and various substitutions, modifications, and changes can be made in the art without departing from the technical spirit of the present invention. It will be apparent to those of ordinary knowledge.

As described above, the present invention can simultaneously take advantage of OFDM, which is resistant to internal symbol interference (ISI), and frequency diversity effect of direct sequence code division multiple access (DS-CDMA). By assigning to a channel, it is possible to transmit at high speed and high quality.

Claims (8)

In the broadband mobile multimedia transmission device for transmitting audio, data and video, Encoding means for receiving the transmission data from the outside and performing channel encoding; Mapping means for receiving data from an encoding means and performing four-phase phase modulation (QPSK) mapping; First multiplication means for receiving data from the mapping means and multiplying a pseudo noise (PN) code input from the outside; Second multiplication means for receiving data multiplied by the pseudo noise from the first multiplication means and multiplying a Walsh code input from the outside; Serial / parallel conversion means for receiving data from the second multiplication means and performing serial / parallel conversion; Inverted fast Fourier transform means for receiving data from the serial / parallel converting means and performing inverted fast Fourier transform (IFFT); Parallel / serial conversion and guard interval symbol insertion means for performing parallel / serial conversion and inserting a guard interval symbol by receiving modulation data from the inverted fast Fourier transform means; Third multiplication means for receiving data from the parallel / serial conversion and guard interval symbol inserting means and multiplying and modulating the high frequency (RF) input from the outside; And Synthesizing means for receiving synthesized data from the third multiplication means and synthesizing and propagating Broadband mobile multimedia transmission device comprising a. The method of claim 1, The bottle / serial conversion and guard period symbol insertion means, And 128 bit 128K modulation data inputted from the inverted fast Fourier transform means to perform parallel / serial conversion and insert a guard interval symbol during 488usec. The method according to claim 1 or 2, The encoding means, It is a convolutional encoder that receives the transmission data such as audio, data, video of 256Kbps from the outside and performs channel encoding to transmit 512Kbps data to the mapping means, The mapping means, A four-phase phase modulation (QPSK) mapping unit which receives 512Kbps of data from the convolutional encoder and performs four-phase phase modulation (QPSK) mapping to transmit two 256Kbps of data to the first multiplication means; The first multiplication means, Two first multipliers for receiving two 256Kbps of data from the four-phase phase modulation (QPSK) mapping unit one by one and multiplying a PN code having a length of 32, respectively, to be transmitted to the second multiplication means. ego, The second multiplication means, Two second multipliers for receiving two data multiplied by the pseudo noise from the two first multipliers and multiplying Walsh codes having a length of 32, respectively, to transmit 8.192 MHz to the serial / parallel conversion means. Is, The serial / parallel conversion means, A serial / parallel converter which receives data of 8.192 MHz from the two second multipliers and performs serial / parallel conversion to transmit 128 64 Kbps data to the inverted fast Fourier transform means; The inverse fast Fourier transform means, 128-point complex inverted fast Fourier transformer which receives 128 64Kbps data from the serial / parallel converter and performs inverted fast Fourier transform (IFFT) to transmit 128 64Kbps modulated data to the parallel / serial conversion and guard interval symbol insertion means Is, The bottle / serial conversion and guard period symbol insertion means, Parallel / serial for receiving 128 64Kbps modulation data from the 128-point complex inverted fast Fourier transformer (IFFT), performing parallel / serial conversion, and inserting a guard interval symbol during 488usec to transmit two data to the third multiplication means. Conversion and guard symbol insert, The third multiplication means, Two third multipliers for receiving two data from the parallel / serial conversion and guard interval symbol inserter one by one, multiplying and modulating by multiplying a high frequency (RF) input from the outside, and transmitting the modulated data to the synthesis means; The synthesis means, And a synthesizer which receives two modulated data from the two third multipliers, synthesizes the signal, and propagates it by airwaves. In the broadband mobile multimedia receiver for receiving audio, data and video, Serial / parallel conversion and guard period symbol detection means for receiving the modulation data propagated from the transmitting apparatus to perform serial / parallel conversion and detect a guard period symbol; Symbol and frame synchronization means for acquiring symbol synchronization and frame synchronization by receiving data from the serial / parallel conversion and guard interval symbol detection means; First storage means for receiving and storing data from the symbol and frame synchronization means; First demodulation means for demodulating by receiving data from the first storage means and performing Fast Fourier Transform (FFT); Second storage means for receiving and storing demodulated data from the first demodulation means; Parallel / serial conversion means for receiving data from the second storage means and performing parallel / serial conversion to transmit data; Despreading means for receiving data from the parallel / serial conversion means and performing despreading; And Second demodulation means for transmitting the decompressed data to the outside after demodulating the despread data outputted from the despreading means Broadband mobile multimedia receiving device comprising a. The method of claim 4, wherein The transmitting device, Encoding means for receiving the transmission data from the outside and performing channel encoding; Mapping means for receiving data from an encoding means and performing four-phase phase modulation (QPSK) mapping; First multiplication means for receiving data from the mapping means and multiplying a pseudo noise (PN) code input from the outside; Second multiplication means for receiving data multiplied by the pseudo noise from the first multiplication means and multiplying a Walsh code input from the outside; Serial / parallel conversion means for receiving data from the second multiplication means and performing serial / parallel conversion; Inverted fast Fourier transform means for receiving data from the serial / parallel converting means and performing inverted fast Fourier transform (IFFT); Parallel / serial conversion and guard interval symbol insertion means for performing parallel / serial conversion and inserting a guard interval symbol by receiving modulation data from the inverted fast Fourier transform means; Third multiplication means for receiving data from the parallel / serial conversion and guard interval symbol inserting means and multiplying and modulating the high frequency (RF) input from the outside; And Synthesizing means for receiving synthesized data from the third multiplication means and synthesizing and propagating Broadband mobile multimedia receiving device comprising a. The method according to claim 4 or 5, The first demodulation means, And a bit number of the input value is 8 bits. The method of claim 6, The despreading means, And a 4-bit number of input values. The method according to claim 4 or 5, The serial / parallel conversion and guard period symbol detection means, A serial / parallel conversion and guard interval symbol detector which receives the modulated data propagated from the transmission device, performs serial / parallel conversion, detects a guard interval symbol, and transmits two 8-bit data to the symbol and frame synchronization means; The symbol and frame synchronization means, Two symbol and frame synchronizers for receiving two 8-bit data from the serial / parallel conversion and guard interval symbol detectors one by one to obtain symbol synchronization and frame synchronization and transmitting two 8-bit data to the first storage means. , The first storage means, Receiving two 8-bit data from the two symbols and the frame synchronizer one by one, storing 128 result values of the 128-point complex inverted fast Fourier transformer (IFFT) of the transmitting apparatus, and then storing the 128 result values in order; Two first storage units for transmitting to the demodulation means; The first demodulation means, 128 points for receiving 128 result values from the two first storage units and performing fast Fourier transform on the contrary to the 128-point complex inverted fast Fourier transformer (IFFT) of the transmitting device to transmit demodulated data to the second storage means. Orthogonal Frequency Division Multiplexing (OFDM) demodulator, The second storage means, Two second storage units which receive two pieces of demodulated data one by one from the 128-point OFDM demodulator and store four-bit data to the parallel / serial conversion means; The bottle / serial conversion means, Two bottle / serial converters which receive 4-bit data from the two second storage units and perform one-to-serial conversion and transmit them one by one to the despreading means; The despreading means, Two matched filters which receive 4-bit data from the two parallel / serial converters and perform despreading to be transmitted to the second demodulation means; The second demodulation means, Quadrature Phase Shift (QPSK) for reconstructing the data by determining whether the despread data values output from the two matching filters are greater than or equal to '0' or less, and then transmitting the reconstructed data to an external image signal processing stage. Keying) Broadband mobile multimedia receiver, characterized in that the demodulator.

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