In this paper, we propose an efficient architecture based on pre-computation for Viterbi decoders incorporating T-algorithm. Through optimization at both. A Fast ACSU Architecture for Viterbi Decoder Using T-Algorithm. Jinjin He, Huaping Liu, Senior Member, IEEE, and Zhongfeng Wang*, Senior Member, IEEE. High performance ACS for Viterbi decoder using pipeline T-Algorithm .. Z. Wang, A fast ACSU architecture for Viterbi decoder using T-Algorithm, in: Proc.

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In order to reduce the computational complexity as well as power consumption, low power schemes should be exploited for the VD in a TCM decoder.

Low power Viterbi decoder for Trellis coded Modulation using T-algorithm

Viterbi decoder Search for additional papers on this topic. Com-pared with the conventional T-algorithm, the computational overhead of this architecture is 12 addition operations and a comparison, which is slightly more than the number obtained from the evaluation in 5. General solutions for low viterib viterbi decoder design will be studied in our implementation work. Very large scale integration VLSI systems. After that, the decision bits are vecoder in and retrieved from the SMU in order to decode the source bits along the final survivor path.

This is because the former decoder has a much longer critical path and the synthesis tool took extra measures to improve the clock speed.

A fast ACSU architecture for Viterbi decoder using T-algorithm

To overcome this drawback, T-Algorithm has proposed in two variations, the relaxed adaptive VD [7], Which suggests using an estimated optimal path metric, instead of finding the real one each cycle and the limited-search parallel state VD based on scarce state transition [SST][8]. NSP, digital communications by satellite. If the target throughput is moderately high, the proposed architecture can operate at a lower supply voltage, which will lead to quadratic power reduction compared to the conventional scheme.

The output of the priority encoder would be the unpurged state with the lowest index.

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User Username Password Remember me. Viterbi decoder Viterbi algorithm Convolutional code Clock rate Computation. In order to further shorten the critical path, we explore the 2-step pre-computation design next.

So, the computational over head and decoding latency due to predecoding and re encoding of the TCM signal become. Therefore, it is worth to discuss the optimal number of precomputation steps.

Critical path method Overhead computing Prunes. By clicking accept or continuing to use the site, you agree to the terms outlined in our Privacy PolicyTerms of Serviceand Dataset License. Typically a TCM system employs a high rate convolutional code, which leads to high complexity of viterbi decoder for the TCM decoder, when the constraint length of Convolutional code is also normal.

Viterbi Convolutional Encoding and Viterbi Decoding. In the 1-step pre-computation architecture, we have pointed decider that for the particular code shown in Fig. A total of received symbols 12 bits are simulated. For VD in-corporated with T- algorithm, no state is guaranteed to be active at all clock cycles.

For clarity, we only provide the main conclusion here. In this section, we address an important issue regarding SMU design when T -algorithm is employed. For the convenience of our discussion we define the left most register viferbi Fig.

The synthesis targets to achieve the maximum clock speed for each case and the results are shown in Table III. Therefore, the hardware overhead of the proposed VD is expected. Thus we usinv focus on the power comparison between the full trellis VD and the proposed scheme. This information ascu us to obtain the 2-step pre-computation data path.

Where q is any positive integer that is less than n. This process is straightforward, although the mathematical details are tedious. This paper has 27 citations. Abdul SubhanDikpal Reddy Trellis coded modulation schemes are used in many bandwidth efficient systems.

First, we expand Ps at the current time slot n Ps n as a function of Ps n-1 to form a look-ahead computation of the optimal P-Popt n. Very Large Scale Integr. The use of convolutional architectuure with probabilistic decoding can significantly improve the error performance of a communication system [1].

Therefore, for high-speed applications, it should not deocder considered. The 64 states and path metrics are labeled from 0 decodsr Usually, the extra delay can be absorbed by an optimized architecture or circuit design.

On the other hand the SST based scheme requires predecoding and re encoding process and is not suitable for TCM decoders. The functional diagram of the 1-step pre-computation scheme is shown in Fig. To fully achieve the iteration bound, we could add another pipeline stage, though it is very costly. Modern digital communication systems usually employ convolutional codes with large constraint length for good decoding performance, which leads to large complexity and power consumption in Viterbi decoders.

Convolutional encoding with viterbi decoding is a good forward error correction suitable for vitterbi affected by noise degradation.

A fast ACSU architecture for Viterbi decoder using T-algorithm – Semantic Scholar

Usig have also analyzed the precomputation algorithm, where the optimal precomputation steps are calculated and discussed. The Ps of the current iteration are stored in the path metric unit PMU. The BMs are categorized in the same way and are described by 8.

Again, to simplify the evaluation, we consider, a code with a constraint length k and q precomputation steps. Even if the extra delay is hard to eliminate, the resultant clock speed is very close to the theoretical bound. Therefore, to maintain a good BER performance, the minimum threshold we chose is 0. Section III presents the precomputation architecture with T-algorithm. Suppose that we viterbbi labeled the states from 0 to References Publications referenced by this paper.

As a result, the de-coding speed of the low-power VD is greatly improved. Later in the next section we will report ASIC implementation results that have not been obtained earlier.