KR20010065131A - Apparatus for transmitting high speed data through traffic channel in WLL system - Google Patents

Abstract

PURPOSE: An apparatus for transmitting high-speed data through a traffic channel of a wireless local loop is provided to transmit high-speed data of 384 Kbps by controlling rate of a convolutional encoder, thereby transmitting high-speed data and moving pictures as well as voice. CONSTITUTION: A rate="3/4", K="9" convolutional encoder(21) receives traffic channel bit for performing convolutional encoding of rate="3/4", K="9" for enabling high-speed data transmission. A block interleaver(22) receives the output of the rate="3/4", K="9" convolutional encoder for performing block interleaving. A scrambling code generating part(23) generates a scrambling code at the speed of 512 Kbps for a traffic channel. The first adding part(24) adds the outputs of the block interleaver(22) and the scrambling code generating part(23). A serial to parallel converter(25) converts a serial signal outputted from the first adding part(24) into a parallel signal. A symbol repetition part(26) regenerates spread symbols outputted from the serial to parallel converter(25). The second and third adding parts(27,28) add the output of the symbol repetition part(26) with Hadamard code and PN(Pseudo Noise) chip rate. The fourth and fifth adding parts(29,30) add the outputs of the second and third adding parts(27,28) with forward link I-channel sequence and Q-channel sequence. A pair of baseband filters(31,32) filter the outputs of the fourth and fifth adding parts(29,30). The first and second multiply parts(33,34) multiply the outputs of the base-band filters(31,32) by cos(2 πfc t) value and sin(2πfc t). An accumulation part(35) accumulates the result of the first and second multiply parts(33,34).

Description

Apparatus for transmitting high speed data through traffic channel in WLL system

The present invention relates to a high-speed data transmission apparatus through a traffic channel of a wireless subscriber network (WLL) system, and more particularly to a wireless local network (WLL) using a direct sequence-code division multiple access (DS-CDMA) communication scheme. Of wireless subscriber network system that adjusts the rate of convolutional encoder in the system to transmit 384 Kbps of high speed data and is suitable for transmitting not only voice but also high speed data and video through WLL system. A high speed data transmission apparatus through a traffic channel.

In general, a communication system is a system that performs information processing by combining a terminal with a remote communication line, and there are wired and wireless communication systems.

The wireless communication system is a communication system for mobile devices such as people, cars, ships, trains and aircraft, including mobile phones (mobile phones, vehicle phones), port phones, aircraft phones, mobile public phones (trains, cruise ships, Installed on express buses, radio calls, radiotelephones, satellite communications, amateur radio, and fishing service ships. These communications include the Advanced Mobile Phone Service (AMPS) system using analog methods, the CDMA and TDMA (Time Division Multiple Access) systems using digital methods, and the Frequency Division Multiple Access (FDMA) systems. , WLL (Wireless Local Loop) system.

1 is a block diagram of a data transmission apparatus of a conventional wireless subscriber network system, showing a forward traffic channel of a communication system.

As shown in the drawing, r = 1/2 k = 9 convolutional encoder (1) for receiving convolutional encoding of rate = 1/2 and K = 9 by receiving traffic channel bits. )Wow; A symbol puncturing unit (2) which receives the output of the r = 1/2 k = 9 convolutional encoder (1) and performs symbol puncturing; A block interleaver (3) which receives the output of the symbol puncturing unit (2) and performs block interleaving; A scrambling code generator 4 for generating a scrambling code at a fixed rate of 16 Kbps for the traffic channel; A first adder (5) for coupling the output of the block interleaver (3) and the scrambling code generator (4); A serial / parallel converter (6) for converting the serial signal output from the first adder (5) into a parallel signal; A symbol repetition unit 7 for regenerating a spread symbol output from the serial / parallel conversion unit 6; Second and third adders (8) (9) for coupling the output of the symbol repetition unit (7) with a Hadamard code and a PN (Pseudo Noise) chip rate, respectively; Fourth and fifth adders (10) (11) for combining the output of each of the second and third adders (8) (9) and the I channel sequence and the Q channel sequence of the forward link, respectively; Baseband filters (12) (13) for baseband filtering the outputs of the fourth and fifth adders (10) (11), respectively; First and second multipliers 14, which multiply the output of the baseband filters 12, 13 by cos (2πf _c t), where f _c is a Carrier Frequency value and sin (2πf _c t), respectively. 15); It consists of an accumulator 16 accumulating the results of the first and second multipliers 14, 15.

Referring to the operation of the conventional device configured as described above in detail.

First, the convolutional encoder with source coded (8Kbps, 16Kbps-> vocoder; 32Kbps-> PCM; 64Kbps-> ADPCM; 80Kbps, 144Kbps-> data) traffic bits are rate = 1/2, constraint K = 9 By going through (1), it is twice the signal source bit rate.

In addition, the symbol puncturing unit 2 punctures 160 Kbps and 288 Kbps data periodically to form symbols having 128 Kbps and 256 Kbps, respectively, and passes through the symbols of other speeds without any action.

Thereafter, the scrambling code generator 4 generates a scrambling code whose speed is fixed at 16 Kbps, and then randomizes the punctured code with this code. Therefore, the randomized code is dropped by half again through the serial / parallel conversion unit 6, the symbol repetition unit 7 adjusts the speed to 128 Kbps, and is a quadrature code that distinguishes channels. Quadrature Phase Shift Keying (QPSK) spreading is performed using a PN sequence for classifying the PN sequence and then transmitted to a terminal station through a QPSK modulator.

However, in the prior art, data rates that can be transmitted are limited to 8, 16, 32, 64, 80, and 144 Kbps. In order to satisfy the demand for high speed multimedia services such as the Internet and video telephony, a high speed data service of 384 Kbps Although necessary, there is a limitation in the prior art that it is not possible to process data at this speed.

Accordingly, the present invention has been proposed to solve the above-mentioned conventional problems, and an object of the present invention is to transmit high-speed data of 384 Kbps by adjusting the rate of a convolutional encoder in a WLL system using a DS-CDMA communication scheme. The present invention provides a high speed data transmission apparatus through a traffic channel of a wireless subscriber network system capable of transmitting high speed data and video as well as voice through a WLL system.

In order to achieve the above object, a high-speed data transmission apparatus through a traffic channel of a wireless subscriber network system according to the present invention,

A r = 3/4 k = 9 convolutional encoder that receives the traffic channel bits and performs convolutional encoding of rate = 3/4 and K = 9 to enable high-speed data transmission; A technical feature of the present invention is that the block interleaver receives the output of the r = 3/4 k = 9 convolutional encoder and performs block interleaving.

1 is a block diagram of a data transmission apparatus of a conventional wireless subscriber network system;

2 is a block diagram of a high speed data transmission apparatus through a traffic channel of a wireless subscriber network system according to an embodiment of the present invention;

3 is a block diagram of a general convolutional encoder;

4 is a diagram illustrating a data flow in general block coding.

5 is a diagram illustrating a data flow in general convolutional coding.

Explanation of symbols on the main parts of the drawings

21: r = 3/4, k = 9 convolutional encoder 22: block interleaver

23: scrambling code generation unit 24, 27 ~ 30: addition unit

25: serial / parallel conversion unit 26: symbol replication unit

31, 32: baseband filter 33, 34: multiplier

35: accumulator

Hereinafter, an embodiment according to the technical concept of the high-speed data transmission apparatus through the traffic channel of the wireless subscriber network system as described above is as follows.

2 is a block diagram of a high speed data transmission apparatus through a traffic channel of a wireless subscriber network system according to an embodiment of the present invention.

As shown in the figure, r = 3/4 k = 9, which enables high-speed data transmission up to 384 Kbps by performing convolutional encoding of the rate = 3/4 and K = 9 by receiving traffic channel bits. A convolutional encoder 21; A block interleaver 22 which receives the output of the r = 3/4 k = 9 convolutional encoder 21 and performs block interleaving; A scrambling code generator 23 for generating a scrambling code at a speed of 512 Kbps for the traffic channel; A first adder (24) for coupling the output of the block interleaver (22) and the scrambling code generator (23); A serial / parallel converter 25 for converting the serial signal output from the first adder 24 into a parallel signal; A symbol replication unit 26 for regenerating the spread symbol output from the serial / parallel conversion unit 25; Second and third adders (27) (28) for combining the output of the symbol repetition section (26) with the Hadamard code and the PN chip rate, respectively; Fourth and fifth adders (29) (30) for combining the output of each of the second and third adders (27) (28) and the I channel sequence and the Q channel sequence of the forward link, respectively; Baseband filters (31) (32) for baseband filtering the outputs of the fourth and fifth adders (29) (30), respectively; First and second multipliers (33) (34) for multiplying the outputs of the baseband filters (31) (32) by the cos (2πf _c t) and sin (2πf _c t) values, respectively; It consists of an accumulator 35 for accumulating the results of the first and second multipliers 33 and 34.

The operation of the high speed data transmission apparatus through the traffic channel of the wireless subscriber network system according to the present invention configured as described above will be described in detail with reference to the accompanying drawings.

First, the error correction code has a tree code and a block code, and the tree code has a linear tree code. The linear tree code has a linear recurrent codes and a control code. There are convolutional codes.

The convolutional code here improves the additive white Gaussian noise (AWGN) characteristics, improves the burst error of the channel in the case of interleaving, facilitates the decoding, and the coding of the multi-rate. There are properties that make it easier to perform.

These convolutional codes are: VSAT (Very Small Aperture Terminal), DBS (Direct Broadcasting Satellite), HDTV (High Definition TeleVision, High Definition Television), MSAT (Mobile Satellite), INMARSAT Applied to satellite communications, such as the International Marine Satellite Telecommunication Organization (CEPT), and the Conference of European Administrations of Posts and Telecommunication (CEPT) Global System for Mobile communication (GSM) It also applies to Globalization Systems (CDMA) systems, the Cellular Telecommunications Industry Association (CTIA) Digital Cellular Systems (IS-54, IS-95), and PDC (Personal Digital Cellular). Used in wireless communication systems.

So the operation of the (n, k, m) convolutional encoder is as follows.

Where m is a memory, k is an input, n is an output, and a convolutional encoder is a linear sequential circuit with such m, k, m.

The linear block code can be expressed using integer n, k, and a generation matrix or a generation polynomial, and has the characteristic that the code words of the n-tuple are uniquely determined for the input message of the k-tuple. Convolutional codes, on the other hand, can be represented by three integers n, k, and m. The integer m is called the constraint length, and the number of stages of the k-tuple in the shift register of the encoder Indicates. Unlike the block code, the characteristics of the convolutional code have memory elements, so that the output of the n-tuple is generated not only with the input of the k-tuple but also with the previous (m-1) k-tuple inputs.

In most cases, convolutional codes yield n = 2, k = 1, (2, 1, m), rate 1/2, and m = 3, k = 1, (3, 1, m), rate 1/3. Have

3 is a block diagram of a general convolutional encoder, which is an example of a convolutional code showing an example of (2, 1, 3).

In Fig. 3, SRG is a shift register.

Here, the regression formula is the same as Equation 1 and Equation 2 below.

u _l-2 u _l-3

u _l-1 u _l-2 u _l-3

4 is a diagram illustrating a data flow in general block coding.

Where U is the k-dimensional input vector, X is the n-dimensional output vector, and G is the k × n generation matrix. Thus, the code rate R _c = k / n is obtained, and a block of k symbols is converted into a block of n symbols.

5 is a diagram illustrating a data flow in general convolutional coding.

The encoder is composed of km shift registers and n modulo-2 adders. Each time k bits are shifted to the first k steps, all bits in the register are shifted to the right, and the outputs of the n adders are sampled in order to represent a binary codeword. These codewords are then converted into waveforms for transmission over the channel. The code rate of the convolutional code may be represented by k / n.

So a block of k symbols is converted to a block of n symbols, which has the memory of the previous block.

Meanwhile, the operation of the present invention will be described in detail with reference to FIG. 2.

Operation at 8, 16, 32, 64, 80 and 144 Kbps is the same as the existing standard.

Since 384 Kbps data is not a data rate that can be extended to the basic Hadamard code used in the domestic WLL standard, it cannot be implemented in a conventional structure. This is because one bit of 384 Kbps data does not include one cycle of the basic Hadamard code or the extended Hadamard code.

Thus, by adjusting the rate of the convolutional encoder used in the conventional structure, the functional blocks of the stage can be used as it is and a 384 Kbps traffic channel can be created.

That is, in 384 Kbps mode, if the traffic channel bits to be transmitted at 384 Kbps are passed through the convolutional encoder with rate = 3/4 instead of the convolutional encoder with rate = 1/2 and constraint length = 9, the data has a bit rate of 512 Kbps. Becomes The data is passed through the block interleaver (option) 22 and the scrambling code generation unit 23, respectively, and then separated into I and Q paths having a bit rate of 256 Kbps by the serial / parallel conversion unit 25.

256 Kbps can be created by extending the default Hadamard code set.

The I and Q paths are multiplied by Hadamard codes orthogonal to other channels, respectively, and then QPSK spreaded in a PN sequence and then transmitted through a QPSK modulator.

In other words, by switching the convolutional encoder according to the transmission rate, a traffic channel of 384 Kbps can be created.

As described above, the present invention adjusts the rate of the convolutional encoder in the WLL system using the DS-CDMA communication scheme to transmit high-speed data of 384 Kbps, thereby transmitting not only voice but also high-speed data and video through the WLL system.

Although the preferred embodiment of the present invention has been described above, the present invention may use various changes, modifications, and equivalents. It is clear that the present invention can be applied in the same manner by appropriately modifying the above embodiments. Accordingly, the above description does not limit the scope of the invention as defined by the limitations of the following claims.

As described above, the high-speed data transmission apparatus through the traffic channel of the wireless subscriber network system according to the present invention increases the transmission rate to 384 Kbps by adjusting only the rate of the convolutional encoder in the domestic WLL system having the maximum transmission bit rate of 144 Kbps. For example, 384 Kbps channel data can be encoded using a convolutional encoder with rate = 3/4, and then encoded data can be transmitted using the existing structure. There is an advantage that can effectively provide a multimedia service.

Claims (1)

A data transmission apparatus through a traffic channel of a wireless subscriber network system, A r = 3/4 k = 9 convolutional encoder that receives the traffic channel bits and performs convolutional encoding of rate = 3/4 and K = 9 to enable high-speed data transmission; And a block interleaver configured to receive the output of the r = 3/4 k = 9 convolutional encoder and perform block interleaving.