Optimal Huffman Coding Research Articles

Optimal Huffman Coding Performance of Ad-Hoc Networks Based on Cross-Layer Design.

Effective data compression and sustainable management of limited bandwidth are the fundamental challenges in the design of current ad-hoc wireless networks. Dynamic Huffman coding protocol with optimal prefix-free codewords assigned to network parameters through cross-layer methodology can considerably address these issues for performance enhancement in these networks. In this paper, the entropy based Huffman binary and ternary coding schemes are implemented with cross-layer design in mobile ad-hoc networks. This cross-layer approach for achieving higher adaptivity incorporated four layers of the traditional networking stack. The simulation results demonstrated the performance tradeoff between throughput and coding metrics for the proposed cross-layer architecture. Moreover, our proposed model exhibits substantially higher compression ratio and coding efficiency than the other existing methods through the integration of this lossless coding protocol in the developed cross-layer framework.

Analysis of Dont Care Bit Filling Techniques for Optimization of Compression and Scan Power

Test power and test time have been the major issues for current scenario of VLSI testing. The test data compression is the well known method used to reduce the test time. The don’t care bit filling method can be used for effective test data compression as well as reduction in scan power. In this paper we describe the algorithm for don’t care assignment like MT(Minimum Transition)-fill technique and hamming distance based technique.The selective Huffman ,optimal Huffman and modified selective Huffman coding are applied on the mapping set to give the optimum Compression and weighted transition matrix is used for scan power Using these techniques find compression and scan power parameters like average power and peak power and conclude that MTfill technique gives low peak and average powers and Hamming distance based modified selective Huffman coding technique gives higher compression ratio compare to another methods like selective and optimal Huffman coding.

Image Compression Based on Wavelet and Quantization with Optimal Huffman Code

paper proposes a method for the compression of color images by Haar transform, quantization and construction of minimum redundancy code using conventional Huffman coding. Wavelet compression is accomplished by decomposing the row and column of the image matrix using the Harr transform. And the reconstruction of the image is feasible just from 1/4 th of the decomposed image and even 1/16 th of the decomposed image is enough for re-construction and the quality relies on the nature the image. A fast and effective histogram-based quantization is applied to the decomposed image. The weighted minmax quantization incorporates activity weighting, whereby obtaining high quality quantized image with significantly less visual distortion. Partition based Huffman coding divides symbols based on sorted probabilities of symbols into two equal halves and generates codes for each portioned symbols. Analytical and experimental results suggest that the optimum code can be generated for images with balanced binary partition Huffman coding, which is not only decodable but also offers the possibility of realizing an average code-word length that can be made arbitrarily close to the source entropy.

Optimizing Bandwidth of Call Traces for Wireless Embedded Systems

Call traces expose runtime behaviors that greatly aid system developers in profiling performance and diagnosing problems within wireless embedded applications. Strict resource constraints limit the volume of trace data that can be handled on embedded devices, especially bandwidth limited wireless embedded systems. We propose two new call trace gathering techniques, local identifier logging and control flow logging, which provide significant reductions in bandwidth consumption compared to the current standard practice of global identifier logging. Intuition into the savings made possible by the proposed trace gathering techniques is provided by an analytical comparison of the bandwidth required by various call tracing approaches. Confirmation of this intuition is demonstrated through experimentation that reveals log bandwidth savings of approximately 85% compared to global identifier logging using flat name spaces, and 35% compared to global identifier logging using optimal Huffman coding.

Optimal Huffman Coding of DCT Blocks

It is a well-observed characteristic that, when a discrete cosine transform block is traversed in the zigzag order, ac coefficients generally decrease in size and the runs of zero coefficients increase in length. This paper presents a minor modification to the Huffman coding of the JPEG baseline compression algorithm to exploit this characteristic. During the run-length coding, instead of pairing a nonzero ac coefficient with the run-length of the preceding zero coefficients, our encoder pairs it with the run-length of subsequent zeros. This small change makes it possible for our codec to code a pair using a separate Huffman code table optimized for the position of the nonzero coefficient denoted by the pair. These position-dependent code tables can be encoded efficiently without incurring a sizable overhead. Experimental results show that our encoder produces a further reduction in the ac coefficient Huffman code size by about 10%-15%.

Deterministic Built-in Pattern Generation for Sequential Circuits

We present a new pattern generation approach for deterministic built-in self testing (BIST) of sequential circuits. Our approach is based on precomputed test sequences, and is especially suited to sequential circuits that contain a large number of flip-flops but relatively few controllable primary inputs. Such circuits, often encountered as embedded cores and as filters for digital signal processing, are difficult to test and require long test sequences. We show that statistical encoding of precomputed test sequences can be combined with low-cost pattern decoding to provide deterministic BIST with practical levels of overhead. Optimal Huffman codes and near-optimal Comma codes are especially useful for test set encoding. This approach exploits recent advances in automatic test pattern generation for sequential circuits and, unlike other BIST schemes, does not require access to a gate-level model of the circuit under test. It can be easily automated and integrated with design automation tools. Experimental results for the ISCAS 89 benchmark circuits show that the proposed method provides higher fault coverage than pseudorandom testing with shorter test application time and low to moderate hardware overhead.

A fast algorithm for optimal length-limited Huffman codes

An O ( nL )-time algorithm is introduced for constructing an optimal Huffman code for a weighted alphabet of size n , where each code string must have length no greater than L . The algorithm uses O ( n ) space.