Algebraic so and harddecision decoding of generalized. We suggest a lowcomplexity scheme where a single member participates in the decoding of each word. Lets see what soft decision decoding offers soft decision decoding. Let us consider that the threshold voltage chosen by the hard decision decoder is 2.
The hamming distance can be defined as a number of bits that are different between the observed symbol. Sum ms, sum product sp 15, or harddecision decoder, i. Hard decision decoding is a technique in which each symbol of a. A decoder 100 includes circuitry 104, 112, 116, 128 and a soft decoder 108. Harddecision decoding of product codes is usually carried out with a socalled iterative decoder, which is efficient and can correct most error. Currently, most decoding schemes comes under hard decoding. Comparison between soft and hard decision decoding using.
On the use of harddecision ldpc decoders on mlc nand flash. This paper investigates the viterbi algorithm for decoding convolutionally coded messages. The solid line represents the performance of an encoding scheme implementing an iterative hard decision decoding of two interleaved code classes with two iterations. Difference between hard decision and soft decision in. Analysis of hard decision and soft decision decoding algorithms of ldpc codes in awgn. Design of hard and soft decision decoding algorithms of ldpc. Performance analysis of softdecision and harddecision decoding. In previous posts, we have discussed convolutional codes with viterbi decoding hard decision, soft decision and with finite traceback. Jul 17, 2007 the dashed line labeled simple product decoding illustrates the performance of a simple reedsolomon based block product encoding scheme with optimized code parameters. Fpga implementaion of soft decision viterbi decoder. Softdecision decoding of linear block codes based on. This easy book teaches the basic ideas of selection analysis, with out an excessively technical rationalization of the arithmetic utilized in selection analysis.
The soft decision decoders require the softinformation from channel and during the decoding process, the softinformation are passed between the computing units. Hard decoder algorithm could be used if one read is available edc encoder bch encoder edc decoder bch decoder front end detection hard decisions 1,0 decoder. The applied bf decoders require only the hard information read from that memory to decode and thus, by avoiding softinformation sensing, the memory read latency is improved. Hard decision decoding of linear block codes n,k,d linear block code c bpsk modulator bpsk demodulator awgn m i cc n1,c 0 st channel decoder 0 1.
Performance analysis of soft decision and hard decision decoding for error dependent power saving viterbi decoder for mobile devices offor kennedy john department of electricalelectronic engineering, anambra state university, uli abstract this paper investigates the viterbi algorithm for decoding convolutionally coded messages. These concepts are mainly based on harddecision decoding, but there are more powerful softdecision decoding which has higher error correction capability. We will restrict the discussion to hamming codes, where 4 information bits are mapped into 7 coded bits. When you read about decoding techniques you will find hard decoding and soft decoding. They are mainly classified as in hard decision decoding and soft decision decoding respectively. Ber results for harddecision demodulation and llr demodulation with unquantized and softdecision decoding are plotted in red, blue, and black, respectively. Let us know discuss a block coding scheme where a group of information bits is mapped into coded bits. The dashed line labeled simple product decoding illustrates the performance of a simple reedsolomon based block product encoding scheme with optimized code parameters. A new energy saving strategy that may enable receivers to decode convolutionally coded transmissions with lower energy utilization using soft decision decoding. There are various algorithms to deal with decoding of ldpc codes. May 05, 2009 decoding if we code, we of course have also to decode in order to get the original information back. The circuitry is configured to receive channel hard decisions for respective bits of a generalized lowdensity parity check gldpc code word that includes multiple component code words, including first and second component code words having one or more shared bits, to schedule decoding of the gldpc code word.
Hard decision decoding how is hard decision decoding. Pdf the golay code outperforms the extended golay code. In this study, a softdecision decoder is proposed by determining the bit loglikelihood. Abstract many algorithms for soft and nearsoft decision decoding of block codes start by implement ing hard decision decoding. A challenging task in error correction is decoding the codewords that have been received via noisy channels.
Maximum likelihood decoding gives the best performance possible for a code and is therefore used to assess the quality of the code. Observe that the ber is only slightly degraded by using softdecision decoding instead of unquantized decoding. Observe that the ber is only slightly degraded by using soft decision decoding instead of unquantized decoding. Nonetheless, one must take complexity into account, especially in decoding. Softdecision decoding of linear block codes based on ordered. We show that the binary golay code is slightly more power efficient than the extended binary golay code under maximumlikelihood ml, harddecision decoding. Pdf design of hard and soft decision decoding algorithms of. Datadriven ensembles for deep and harddecision hybrid decoding.
A novel multiplebits collision attack based on double detection with errortolerant mechanism abp algorithm is a significant departure from the traditional hard decision decoding of rs codes. Download making hard decisions with decisiontools pdf ebook. Method for iterative harddecision forward error correction. Chapter 2 soft and hard decision decoding performance.
Based on these statistics, two monotonic properties which dictate the reprocessing strategy are derived. Soft and hard decision decoding performance springerlink. Mod01 lec17 coded modulation and soft decision decoding. Ber results for hard decision demodulation and llr demodulation with unquantized and soft decision decoding are plotted in red, blue, and black, respectively. Whereas a harddecision decoder operates on data that take on a fixed set of possible values typically 0 or 1 in a binary code, the inputs to a softdecision decoder may take on a whole range of values inbetween. Harddecision hybrid decoding tomer raviv, nir raviv, and yair beery, senior member, ieee school of electrical engineering, telaviv university telaviv 6997801, israel email.
Pdf soft and hard decision decoding performance researchgate. Han softdecision decoding of binary linear block codes 4 gmd decoding 2 initialization. I am having trouble understanding the difference between hard and soft decision. To reduce the decoding complexity, hard decision decoding hdd is an appealing alternative. Upper and lower bounds on hard and soft decision decoding are discussed. Using this trellis coded modulation design, the paper compares the performance of soft and hard decision decoding of a serially concatenated channel coded. Estimate ber for hard and soft decision viterbi decoding.
Wo2016099646a1 gldpc soft decoding with hard decision. Decoding if we code, we of course have also to decode in order to get the original information back. Soft decision decoding of the 127, 64, 21 bch code compared to hard decision decoding the results for the bch 127, 64, 21 code are shown in fig. For both decoding techniques the outer encoder is a quaternary convolutional encoder while the inner encoder is the extended ce. So the idea behind the encoder is increase the minimum distance at the cost of spectral efficiency.
Softdecision decoding of convolutional code in ieee 802. The difference between hard and soft decision decoder is as follows. This is an outstanding code, and consequently the unquantised soft decision decoding performance is very close to the offset sphere packing bound, being almost 0. Probabilistic amplitude shaping with hard decision decoding and staircase codes article pdf available in journal of lightwave technology 369. Thus, the most optimal path through the trellis is the path with the minimum distance. Hard decoders only take hard decisions bits as the input e. Pdf in this chapter, we discuss the performance of codes under soft and hard decision decoding. Sep 29, 2009 hamming 7,4 code with hard decision decoding by krishna sankar on september 29, 2009 in previous posts, we have discussed convolutional codes with viterbi decoding hard decision, soft decision and with finite traceback. Hard decision decoding takes a stream of bits say from the threshold detector stage of a receiver, where each bit is considered definitely one or zero.
Low complexity viterbi decoder for rscc concatenated codes. The softdecision decoding usually performs better than the harddecision decoding. Pdf performance analysis of softdecision and harddecision. The decoding process is said to be hard when the signal at the input, or output, of the decoder is binary, i. Matlab code for repetition codes hard decision decoding. Hard decision decoding there are different iterative decoding algorithms having two derivations. The idea behind these two was not clear for me until i read a nice explanation. In soft decision, we need to compute m distance metric. Graphs are plotted between viterbi algorithm and fano algorithm for decoding the convolutional codes of fixed code rate and fixed. Jun 23, 2016 the soft decoder is configured to receive the channel hard decisions corresponding to the first component code word, to further receive soft reliability measures that were assigned to the shared bits in decoding the second component code word, and to decode the first component code word based on the channel hard decisions and the soft. Decoding of errorcorrection codes is a hard problem due to the curse of dimensionality, leading one to consider ensemblesofdecoders as a possible solution. In this chapter, we discussed the performance of codes under hard and soft decision decoding. Datadriven ensembles for deep and harddecision hybrid.
On the use of harddecision ldpc decoders on mlc nand. Soft decision and quantised soft decision decoding. Hard vs soft decision decoding tpcs will work with hard decision or soft decision decoding two bit soft decision decoding typically picks up 2 db of additional coding gain additional soft bits can add about 12 db more soft decoder input requires a soft metric bpskqpsk proportional to iq voltage higher order constellations require llr. In hard decision decoding, the received codeword is compared with the all possible codewords and the codeword which gives the minimum hamming distance is selected. This paper presents simulation of viterbi decoder and fano decoder for decoding the convolutional codes in awgn channel. Demodulate the received signal using hard decision and approximate llr methods. Specify unit average power for the received signal. Mar 15, 2012 e perform soft decision decoding f count the number of errors for both hard decision and soft decision decoding g repeat for multiple values of and plot the simulation results.
In powerlimited regime, typically our snr is much smaller than one, whereas in the bandwidthlimited regime, the snr is large. Click here to download matlaboctave script for computing ber for bpsk in hamming 7,4 code with soft and hard decision decoding. Bhavsar and brijesh vala, journalinternational journal of computer applications, year2014, volume90, pages1015. When compared to the same implementation using hard decision decoding, the soft decision decoding gives a better performance of about 2db. In the hard decision decoding, the path through the trellis is determined using the hamming distance measure. This extra information indicates the reliability of each input data point, and is used to form better estimates of the original data. Performance analysis of softdecision and harddecision. The circuitry is configured to receive channel hard decisions for respective bits of a generalized lowdensity parity check gldpc code word that includes multiple component code words, including first and second component code words having one or more shared bits, to schedule decoding of the gldpc code word, and following the decoding, to. Probabilistic amplitude shaping with hard decision decoding. In the case of hard decision decoding hdd, the inner decoderdemodulator only output hard decision code symbols to be decoded by the quaternary outer decoder. Difference between hard decision and soft decision in error.
In fact, if a codeword from the extended code is transmitted, one cannot achieve a higher probability of correct decoding than by simply ignoring the 24th symbol and using an ml decoder for the nonextended code on the first 23 symbols. The following two cases show decoding by hard decision method and soft decision methods. Pdf probabilistic amplitude shaping with hard decision. A comparison of simulation results with theoretical results is also shown.
Standard bch and rs ecc decoding algorithm berlekampmassey algorithm is a hard decision decoder. The softdecision decoders require the softinformation from channel and during the decoding process, the softinformation are passed between the computing units. Performance analysis of softdecision and harddecision decoding for error dependent power saving viterbi decoder for mobile devices offor kennedy john department of electricalelectronic engineering, anambra state university, uli abstract this paper investigates the viterbi algorithm for decoding convolutionally coded messages. The circuitry is configured to receive channel hard decisions for respective bits of a generalized lowdensity parity check gldpc code word that includes multiple component code words, including first and second component code words having one or more shared bits, to schedule decoding of the gldpc code.
With soft decision decoding, the decoding algorithm is identical to the one previously described for hard decision decoding, except that the branch metric is no longer an integer hamming distance but a positive real number if the voltages are all between 0. In the harddecision decoding, the path through the trellis is determined using the hamming distance measure. Hard decision decoding multiple data errors in the data can be corrected if the number of data errors does not overcome the maximum number of errors for which the algorithm was designed. They are classified according to their complexities to get. Pdf design of hard and soft decision decoding algorithms. Probabilistic amplitude shaping with hard decision. It maybe seen as a kind of hard decision decoding procedure. Viterbi decode the signals using hard and unquantized methods. I will try to report this explanation with my own words here on the blog.
For hard decision decoding, the performance of codes in the binary symmetric channel was discussed and numerically evaluated results for the bounded distance decoder compared to the full decoder were presented for a range of codes whose coset leader weight distribution is known. When m is large, the computation complexity is very high. And what we saw was the performance was quite different in the two regimes. Home matlab codes matlab code for repetition codes hard decision decoding 00.
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