KR100288433B1 - 64CM and 256QA TCM decoder - Google Patents

Abstract

64-QAM and 256-QAM combined TCM decoder according to the present invention comprises a control unit for generating a 64-QAM or 256-QAM decoding command signal according to whether the input bit stream is 64-QAM or 256-QAM; An uncode bit memory for storing uncoded bits in the input bits in response to 64-QAM and 256-QAM decoding command signals from the controller; A puncher for depunching the input bit stream; A branch metric for 64-QAM branch metric or 256-QAM branch metric for symbols depunctured by the puncher in response to a 64-QAM decoding command signal and a 256-QAM decoding command signal from the controller; An ACS unit for adding the branch metric and the stored path metric, and comparing the addition values to select an optimal path; A survival memory for detecting a maximum possible symbol after finding an optimal path by a trace algorithm; An uncode bit debuffer for 64-QAM deping or 256-QAM deping from a bit stream from the uncode bit memory based on the largest possible symbol from the survival memory; A differential precoder for differential coding the largest possible symbol from the SMU unit; And a data parser for parsing uncodes from the uncoded bit decoder and differential codes from the differential precoder in response to a 64-QAM decoding command signal and a 256-QAM decoding command signal from the controller. .

Description

64Q and 256QM Combined TCM Decoder

The present invention relates to a Trellis Coded Modulation (TCM) decoder, and more particularly, to a decodeable 64-QAM and 256-QAM combined TCM decoder regardless of whether the input signal is 64-QAM and 256-QAM.

At present, the development of digital technology is accepted that digital systems have sufficient advantages in terms of spectrum and power efficiency, flexibility of service, convergence of multimedia and potential low equipment cost, both visually and audibly compared to conventional analog technology. It is getting in. Moreover, the use of cables for the distribution of video and audio signals to each individual is continually increasing and has already become a viable means for distribution.

ITU-T J.83, Digital Multi-programme systems for television, sound and data services for cable distribution, is a frequency division multiplexed cable network (e.g. cable). System structure, channel coding and modulation for digital multi-program television, sound and data signals distributed throughout the system.

ITU-T J.83 presents four appendices and recommends that cable network services use one of the systems listed in the four appendices.

ITU-T J.83 Annex B describes the frame structure, channel coding, and channel modulation for digital multiservice television distribution systems in cable systems. The specifications in Appendix B cover both 64 and 256 QAM.

In 64-QAM presented in ITU-T J.83 Annex B, the Trellis Coded Modulator contains a 28-bit string of four 7-bit RS symbols whose identifiers are pairs of 'A' and 'B' symbols. Is entered. The 28 bits entered are assigned to the Trellis Group. Each trellis group forms 5QAM symbols. Of the 28 input bits forming the traris group, the two traris groups assigned 4 bits are first coded differentially and then coded by a binary convolutional coder (BCC), respectively. . This coding outputs a total of 30 bits. Thus, the overall coding ratio for 64-QAM trellis code modulation is 14/15.

In addition, in 256-QAM, it is classified into an asynchronous group consisting of 38 data bits and a synchronization group consisting of 30 data bits and 8 sync bits. A 38-bit string of symbols is input to a Trellis coded modulator. The 38 bits entered are assigned to the asynchronous and synchronous Trellis Group according to the group they belong to. Each trellis group forms 5QAM symbols. Of the 38 input bits forming the traris group, the two traris groups allocated by 4 bits are first coded differentially and then coded by a binary convolutional coder (BCC), respectively. . This coding outputs a total of 30 bits. Thus, the overall coding ratio for 256-QAM trellis code modulation is 19/20.

Accordingly, the present invention was created in view of the above circumstances, and an object of the present invention is to provide a decodeable 64-QAM and 256-QAM combined TCM decoder regardless of whether the input signals are 64-QAM and 256-QAM. .

64-QAM and 256-QAM combined TCM decoder according to the present invention for achieving the above object is a 64-QAM decoding command signal or 256-QAM decoding command depending on whether the input bit stream is 64-QAM or 256-QAM A control unit for generating a signal; An uncode bit memory for storing uncoded bits in the input bits in response to a 64-QAM decoding command signal and a 256-QAM decoding command signal from the controller; A puncher for depunching the input bit stream; A branch patrick for 64-QAM branch metric or 256-QAM branch metric for symbols depunctured by the puncher in response to a 64-QAM decoding command signal and a 256-QAM decoding command signal from the controller; An add compare selet (ACS) unit for adding the branch metric and the stored path metric, and comparing the addition values to select an optimal path; A survival memory for detecting a maximum possible symbol after finding an optimal path by a trace algorithm; An uncode bit debuffer for 64-QAM deping or 256-QAM deping from a bit stream from the uncode bit memory based on the largest possible symbol from the survival memory; A differential precoder for differential coding the largest possible symbol from the SMU unit; And a data parser for parsing uncodes from the uncoded bit decoder and differential codes from the differential precoder in response to a 64-QAM decoding command signal and a 256-QAM decoding command signal from the control unit. It is characterized by.

According to the present invention, it is possible to decode 64-QAM and 256-QAM combined TCM decoders regardless of whether the input signals are 64-QAM and 256-QAM.

1 is a block diagram illustrating a 64-QAM and 256-QAM combined TCM decoder according to an embodiment of the present invention.

<Explanation of symbols for main parts of drawing>

110: control unit 120: uncode bit memory

130: puncher 140: branch metric

150: ACS 160: survival memory

170: differential precoder 180: uncode bead decoupler

190: data parser

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

1 is a block diagram showing a 64-QAM and 256-QAM combined TCM decoder according to an embodiment of the present invention.

Referring to FIG. 1, the 64-QAM and 256-QAM combined TCM decoder according to the present invention includes a control unit 110, an uncoded bit memory 120, a depuncturing block 130, and branch metrics. (Branch Metric Calculation; 140), ACS (Add Compare Select; 150), Survivor (Survivor) 160, Differential Precoder (170), Demapping of Uncoded Bits (180), And a data parser 190.

The controller 110 detects whether the input bit string is 64-QAM or 256-QAM, and generates a 64-QAM decoding command signal or a 256-QAM decoding command signal according to the detection result. The controller 110 provides the generated 64-QAM decoding command signal or 256-QAM decoding command signal to all parts of the TCM decoder to perform decoding corresponding to the command signal.

The uncode bit memory 120 stores uncoded uncoded codes in the input 64-QAM or 256-QAM codes in response to a 64-QAM decoding command signal and a 256-QAM decoding command signal from the controller. In response to the decoder's step, the stored 64-QAM or 256-QAM codes are provided to the uncode bead decoder 180.

The puncher 130 depunches the input 64-QAM or 256-QAM codes and provides the branched codes to the branch metric 140.

The branch metric 140 is a 64-QAM branch metric or 256 code depunctured by the puncher 130 in response to a 64-QAM decoding command signal and a 256-QAM decoding command signal from the control unit 110. -QAM branch metric to generate a 64-QAM branch metric or a 256-QAM branch metric. The branch metric 140 outputs the generated 64-QAM branch metric or 256-QAM branch metric to the ACS unit 150. Advantageously, the branch metric 140 comprises 64-QAM branch metric circuits (not shown) and 256-QAM branch metric circuits (not shown) for each of the 64-QAM branch metric and the 256-QAM branch metric. Respectively, and selectively drives the 64-QAM branch metric circuit and the 256-QAM branch metric circuit in response to the 64-QAM decoding command signal and the 256-QAM decoding command signal from the control unit 110.

The ACS unit 150 adds the previously stored path metric to the 64-QAM or 256-QAM branch metric from the branch metric 140, compares the addition values, and selects an optimal path. The selected path is provided to the survivor memory 160.

The survival memory 160 finds an optimal path by a trace algorithm, detects a maximum possible symbol, and transmits the detected maximum possible symbol to the uncode bit memory 180 and the differential precoder 170. Provide each.

The differential precoder 170 differentially precodes the largest possible symbol from the SMU unit and provides differential precoded codes to the data parser 190.

The uncode bit decoupler 180 decodes the uncoded bit decoder 180 based on the maximum possible symbol from the survival memory 160 in response to a 64-QAM decoding command signal from the control unit 110 and a 256-QAM decoding command signal. Uncoded bits from the bit memory 120 are decoded to 64-QAM or 256-QAM, and the decoded decodes are output to the data parser 190.

The data parser 190 parses the uncodes from the uncoded bit decoder 180 and the differential precodes from the differential precoder and outputs decoded codes.

Hereinafter, the operation of the 64-QAM and 256-QAM combined TCM decoder configured as described above will be described in detail.

First, when a TCM code is input, the controller 110 detects whether the input code is 64-QAM or 256-QAM, and according to the detection result, the 64-QAM decoding command signal or 256-QAM decoding command signal. Raises the In this case, the 64-QAM decoding command signal or the 256-QAM decoding command signal generated from the control unit 110 may include the uncode bit memory 120, the branch metric 140, the uncode bead decoder 180, and Each is provided to a data parser 190. The puncher 130, the ASM unit 150, the survivor memory 160, and the differential precoder 170 operate equally to both 64-QAM and 256-QAM.

When the 64-QAM decoding command signal or the 256-QAM decoding command signal from the control unit 110 is input, the uncode bit memory 120 receives the input 64-QAM or 256-QAM code in response to the command signal. Store uncoded uncoded code and provide stored 64-QAM or 256-QAM codes to the uncode bead decoder 180 in response to the decoder's step.

When the TCM code is input, the puncher 130 depunches the input 64-QAM or 256-QAM codes and provides the branched codes to the branch metric 140. The branch metric 140 is a 64-QAM branch metric or 256 code depunctured by the puncher 130 in response to a 64-QAM decoding command signal and a 256-QAM decoding command signal from the control unit 110. -QAM branch metric to generate a 64-QAM branch metric or 256-QAM branch metric, and output the generated 64-QAM branch metric or 256-QAM branch metric to the ACS 150. The ACS unit 150 adds the 64-QAM or 256-QAM branch metric from the branch metric 140 to a previously stored path metric and compares the addition values to select an optimal path, and selects the selected path. To the survivor memory 160.

Then, the survival memory 160 finds an optimal path by a trace algorithm, detects the maximum possible symbol, and stores the detected maximum possible symbol in the uncode bit memory 180 and the differential precoder 170. To each).

The differential precoder 170 differentially precodes the largest possible symbol from the survival memory 160 and provides differential precoded codes to the data parser 190.

On the other hand, when the 64-QAM decoding command signal and the 256-QAM decoding command signal from the control unit 110 are input, the uncoded bit decoder 180 and the 64-QAM decoding command signal from the control unit 110; 64-QAM de-pinging or 256-QAM de-pinging the decodes from the uncode bit memory 120 based on the maximum possible symbols from the survival memory 160 in response to a 256-QAM decoding command signal. The coded uncodes are output to the data parser 190.

Then, the data parser 190 uncodes and differentiates the uncoded bits from the uncoded bit decoder 180 in response to the 64-QAM decoding command signal and the 256-QAM decoding command signal from the controller 110. The differential precodes from the coder are parsed to output the decoded codes.

Therefore, according to the above configuration, it is possible to decode 64-QAM and 256-QAM combined TCM decodable regardless of whether the input signals are 64-QAM and 256-QAM.

According to the present invention, it is possible to realize a 64-QAM and 256-QAM combined TCM decoder capable of decoding 64-QAM and 256-QAM combined TCM, regardless of whether the input signal is 64-QAM or 256-QAM. .

In addition, although the present invention has been described in detail with reference to the embodiments described above, the present invention is not limited thereto, and modifications and improvements are possible within the scope of ordinary knowledge of those skilled in the art.

Claims (1)

A controller for generating a 64-QAM decoding command signal or a 256-QAM decoding command signal according to whether the input bit string is 64-QAM or 256-QAM; An uncode bit memory for storing uncoded bits in the input bits in response to a 64-QAM decoding command signal and a 256-QAM decoding command signal from the controller; A puncher for depunching the input bit stream; A branch metric for 64-QAM branch metric or 256-QAM branch metric for symbols depunctured by the puncher in response to a 64-QAM decoding command signal and a 256-QAM decoding command signal from the controller; An ACS unit for adding the branch metric and the stored path metric, and comparing the addition values to select an optimal path; A survival memory for detecting a maximum possible symbol after finding an optimal path by a trace algorithm; 64-QAM decapping or 256-QAM from the bit stream from the uncoded bit memory based on the largest possible symbol from the survival memory in response to a 64-QAM decoding command signal and a 256-QAM decoding command signal from the controller. An uncode bit decoupler for deping; A differential precoder for differential coding the largest possible symbol from the SMU unit; And And a data parser for parsing uncodes from the uncoded bit decoder and differential codes from the differential precoder in response to a 64-QAM decoding command signal and a 256-QAM decoding command signal from the control unit. Featuring 64-QAM and 256-QAM combined TCM decoders.