International Journal of Trend in Research and Development, Volume 3(2), ISSN: A Review of Coding Techniques in the Frequency

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1 A Review of Coding Techniques in the Frequency Farhad Shoahosseini 1 and Shahram Jamali 2 1 Department of computer, Germi branch, Islamic Azad University, Germi, Iran 2 Associate Professor, University of Mohaghegh Ardabili, Ardabil, Iran Abstract In this paper, the coding methods and reasons for using these methods, we will. Among the available methods for lossless coding methods will be evaluated in a few, because we use these methods to shorten the length of the bit addressing wishes,so if the size of the data before and after the information from the source code will change removed and coding system for all the wrong has been done. In this article we examine how the two methods and Huffman and Shannon-Fano will be discussed in detail. Keywords: Addressing, Variable Length Coding Techniques I. INTRODUCTION The aim of this paper is to introduce various methods of encoding channels of digital communication channels in order to deal with the error. For this purpose, the expression of mathematical theory of G code irrigation methods, introducing different types of code and the universal code irrigation were past their comparison is done. II. CLASSIFICATION CODING METHODS WITHOUT WASTING 1. Encoding Based on Entropy: In this category of methods of data per symbol is considered a unique password. According to Shannon optimum length for every symbol of equation (1) Pursuant to that pi is the probability of the i-th symbol [1]. 1 Log 2 (1) pi Related to entropy coding include: VLE, Hoffman, accounts, etc. 2. The variable-length coding: The variable-length coding Shannon-Fano coding algorithm that is used is as follows [1]: Sort symbols based on repetition frequency Recursively divided into two parts, the sequence of symptoms so that the total frequency of repetitions for both will be the same as long as each section includes a sign be. For example, the word "Araniani" Consider: Table1: The number of occurrences of letters Araniani Figure 1: Shannon-Fano tree So the categories letters will be as follows: i. In each branch segmentation is done in such a way that the total occurrence of letters in each subcategory is equal to or closest. ii. iii. Each branch will continue to remain only a mark. Bits 0 and 1 are assigned to each sub-branch and the path to every mark we set the code mark it will be like 10 for letter "N". The following table of code for each letter in the word "Araniani" show: Table 2: The equivalent code for each letter in the word "Araniani" Letter Number Code The number of bits used A I N R The total number of bits: 16 If you wanted the seven letters to uncompressed 8-bit storage for each character we have considered that overall we need 64 bits. Note: This method is not always uniqueness tree, for example, in the example, the word "Araniani" tree can be plotted below: Letter A I N R Number Figure 2: Other trees for the word "Araniani" Available Online@ 481

2 3. Hoffman Coding: i. Sort symbols on each repetition frequency. ii. Until only remain a symbol repeat the following steps. Two symbols with the lowest frequencies and set down a tree with which we form below and a code they consider equivalent to the parent. Total number of repeat two children under their parents assign new tree. The Hyacinth removed from the list and replaced them by putting their parent. iii. In total, two children and their parents Assigning consistently under the new tree [2]. For example, performing Huffman code for the word "Araniani" is shown in Figure 4. information theory close to zero (log 1 / pi 0) will not be very efficient and the Huffman coding method developed is used.in this way, rather than per symbol of a code word used for a combination of binary symbols is considered. For example, if the alphabet S = {s1, s2,...,sn} of the combination of symbols used k-nk popularity it will be extended alphabet.although developed by Hoffman improvements compared to conventional Hoffman, but the amount is not significant. One problem with this method is that if the value of k is large then the number will be much more developed alphabet and why the symbols table will be large [3]. 5. Adaptive Huffman code: In this method, a static tree is created based on existing data and then get more information from the sender, tree dynamically updated. Figure 3: Huffman tree for the word "Araniani" The following table of code for each letter in the word "Araniani" show. Table 3: coded word "Araniani" Huffman algorithm Letter Number Code The number of bits used A I N R The total number of bits: 16 To decrypt any encrypted file is actually a book there at the beginning of each sequence of bits that defines what the symbol represents. Huffman coding features include: Any code can be prefixed other code, so it will be foggy in the decoding process. For example, the following code table due to lack of these features are obscured. Figure 4: Pseudo-code, adaptive Huffman code A prerequisite for using such a method using the same initial tree and the same update algorithms in the receiver and the Transmitter [3]. Algorithm: Nodes in order from left to right and bottom to top are numbered and the numbers written in parentheses indicates the number of symbolic.features sibling should always be maintained, i.e. all nodes must either increase the number, sorted and otherwise routine is called and the switching node is updated.when switching routine exercise its parent node is less than the number of hops that a greater number is replaced. Figure 6 shows an example of this method [3]. Table 4: Decryption Process The most optimal possible to reduce the amount of redundancy in the code is verifiable, meaning that the average bits corresponding symbols is less than ƞ + 1. Figure 5: Example of adaptive Huffman code 4. Huffman code developed: Hoffman method in situations where the probability of a symbol (pi) is large and the number of bits for symbols based on 6. Arithmetic coding: The arithmetic coding is a newer method is usually a better result compared to the Huffman code. Consultants in Huffman code is Available Online@ 482

3 assigned to each symbol a password that the correct number of bits for which it is intended, whereas the total account coding data can be encoded with a number[4]. Per symbol due to its repetition frequency data with a probability of occurrence and the corresponding period considered, For example, for the word "Araniani" and the probability of each of the letters corresponding period will be as follows: 7. Coding-based Dictionary: In this category the following strings are usually set in a building that dictionary is stored and a password whenever the pattern matching one of the entries found in the dictionary, it will be replaced with equivalent code in Dictionary. Dictionary based coding can be RLE, LZW noted. 7.1 Coding RLE: A simple method of coding sequence in which the same data for a specified number of data along with the data stored numbers: Figure 6: Probability and the corresponding period of each of the letters of the word "Araniani" Data encrypted with the numerical equivalent of each interval of (0,1] shown. This range is determined based on the symbols and intervals corresponding to each symbol period with increased length also will be limited. For example, for the word "Araniani" are: Table 5: Number of repeat and play for the word "Araniani" in the arithmetic coding Letter A I R N Number Range [0,0.4) [0.4,0.6) [0.6,0.8) [0.8,1) i. For the letter "A" range [0,0.4) we choose. ii. Interval [0,0.4) again divided based on each letter we intervals. iii. Second interval for the letter "i" is picked. iv. The algorithm will continue to the last letter. Finally intervals equivalent to the word "in" [0.224,0.24) will be the beginning of the period considered is to encode data. For storage or transmission attempt, the shortest interval to be extracted sequence numbers, for example, 0.24 and 0.23, respectively binary equivalent of million and and is thus simply to store the word "in" of 5 bits a. In arithmetic coding compression is not guaranteed and may increase the storage volume occur[4]. In the process of decoding the image above operation is performed, for example, will be 0.87: v. Since the 0.87 About [0.8,1) the letter "N" we choose. vi. Since 0.87 in [0.8,0.88) the word "A" we choose. vii. Finally, continue above the letter "an" is obtained. Utilization: This method is widely used in the storage of binary images. Video IFF, PCX and TGA of the compression method used. The method used to send faxes because the fax sequence of black and white dots. No memory resource that is the source of its information (symbols, etc.) are scattered independently, meaning that the value of each symbol is not related to previous symbols. Runlength coding instead of taking the default source without memory, with memory source information in the form it assumes [3]. Figure 8: An example of a binary image compression coding method using Run-length. 7.2 Coding LZW: LZW method of password fixed length to represent a sequence of symbols with variable length are usually the source uses. Like words in a text [6]. LZW encoding and decoding in the same dictionary dynamically while receiving information to the user. In this way gradually Dictionary entries are longer. In this algorithm LZW compression in GIF images used that image to one-third of the average volume decrease. Pseudo code of the compression algorithm LZW: Figure 7: The process of decoding the coding arithmetic Figure 9: Lempel-Ziv algorithm pseudo code For example, suppose you compress a sequence of words, from a simple glossary contains 3 characters to use. Available Online@ 483

4 Table 6: The sequence of words of a simple glossary contains 3 characters If the input of this example sequence "ABABABABAB", the LZW compression algorithm will be as follows: Table 7: LZW compression algorithm for sequence ABABABABAB So for ABABABABAB input in output encoding code: would be only 9 instead of sending 14 character code is sent, the compression ratio is equal to 9/14. Figure 10: Pseudo-code decoding algorithm LZW So for input decoder output will be as follows: Table 8: Output: ABABABABAB In actual applications are usually specified domain will be considered for the ZIP code. Dictionary at first and up to a maximum size will be 210 2lmax will increase. The compression of the code length to the size lmax of empty storage methods used. 8. Addressing Network: Address Internet Protocol or IP address, for short, is used to connect computers to each device and the computer network profile based on TCP / IP, including the Internet works, are allocated. Messages that you send to each other computers, numerical symbol associated with it, such as network routers and recipient address in a mailing interpret, to finally reach the desired message to the computer network interface. 8.1 IP version 6 IP addresses can also be called next generation IP version 6 address. Although it has been almost ten years on the IPv6 protocol features and standards work, but has recently been finalized. Moreover, some aspects of it are still working and is organized by the working groups. As mentioned in the previous section issued by the IPv4 address was insufficient for comprehensive solutions. This has forced designers to work on the new version of the protocol and do it in such a way that they do not again faced with the same issues. Internet Protocols are the members of the association responsible for the development of any new protocol developed by RFC carefully scrutinize and examine. RFC protocols are records that provide details and features. So the makers of software and hardware in this way they will know how to apply the protocol standards. This standardization makes Providers Software and hardware apart from a protocol expertise to develop a plan and follow the same program.as I understand the structure and performance of IPv6 and IPv4 is vital for addressing it properly should take advantage of it to accurately understand the concept and mechanism of action. IPv6 addresses are 128 bits in length, which have very much space at our disposal. During IPv6 addresses from IPv4 are much larger. But what other features IP protocol is different than previous versions? i. First of all, instead of the 4 groups, 8 groups of numbers and to separate them, instead marks the spot, the ":" is used. But the letters also clearly be seen in the numbers. ii. Increase the size of an address IP, the IP version 6, 128- bit addressing is available. 128-bit address space means that you can have 2 ^ 128 different address. This means 340,282,366,920,938,000,000,000,000,000,000, 000, 000 address provided by IPv6. So if any IPv6 have a weight equal to 56 times the weight of the Earth's total IPv Advantages and Disadvantages of IPv4 and IPv6 The current IP infrastructure IPv4 IPv6 is the new version that really apply to many companies and companies switch to this version will include heavy and costly. As the number of users on the network caused a strong need to address the many network professionals to upgrade their bandwidth or amount of addressable users, To address shortage will face less problems in the meantime, but that one of them changing hardware or router interface by changing the bandwidth must be changed, and that was the problem with thinking about future. That's why the decision to upgrade the network software (is meaning, using the Port for addressing more to users ) were imposed almost zero address the problem, but only objection is the biggest flaw in broadband remains the most important reason to slow down.in general it can be the difference in bandwidth and data transfer speeds as well as addressing the more users there. IPv6, the new protocol to the next generation Internet Protocol, or IPNG is well known that in 1994 the Internet Engineering Available Online@ 484

5 References Headquarters or IETF draft was proposed and adopted it in This complete standards and all its parts until the fall of 2001 was part of the agenda of the IETF. In the past eight years IPv6 network types have been tested in more than 40 countries. Japan already offers IPv6 addresses to their consumers. It is expected that the transition from IPv4 to IPv6 over the next decade or perhaps more to be done. Top features of IPv6, increasing the address space from 32 bits to 128 bits, the IP addresses from 4 billion to 35 trillion tank increases. And the interesting thing is that despite this increase, the processing of IP packets will not be complicated. IPv6 packet header format because it is easier. In addition, the IPv6 capability also provides for priority based on the content that will ultimately improve efficiency and speed up content delivery. Since the transition to IPv6 requires changes to the devices and drivers and operating systems, hesitate in the implementation of this standard is acceptable. But the design is done in a way that the transition to IPv6 is a gradual process to take place. In fact, there is no specific time for a full transition to this standard, although some countries such as the United States require Internet servers to IPv6 will be equipped by the end of 2008, but many networks can be a combination of IPv4 and IPv6 standards used to give. CONCLUSION In this article we examined data coding techniques and methods of coding, lossless coding of expression. And addressing methods mentioned and because of the great importance of IPv6, the addressing mode was discussed. [1] Kuhn.F, T. Moscibroda, and R. Wattenhofer, Initializing newly deployed ad hoc and sensor networks,. In Proceedings of the 10th annual international conference on Mobile computing and networking (MobiCom 04). [2] Knuth, Donald E. "Dynamic huffman coding." Journal of algorithms 6.2 (1985): [3] Lee.S, Asano.T, and Kim.K,2006."RFID mutual authentication scheme based on synchronized secret information, Symposium on Cryptography and Information Security", SCIS, Hiroshima, Japan, January2006 [4] Liu.B.H, 2005, "Adaptive Protocol Suite for Wireless Sensor and Ad Hoc Networks", the University of New South Wales, Sydney, Australia, November 2005 [5] Md. Yusuf Sarwar Uddin, Mohammad Ashiqur Rahman and Md.Mostofa Akbar,2006. "Hierarchical Numbering Based Routing Protocol forwireless Ad hoc Networks", Proc. of 1st International Conference onnext Generation Wireless Systems 2006 (ICNEWS06), Dhaka, pp , January [6] NIST, A wireless ad hoc network, Advanced Network Technologies Division, National Institute of Standards and Technology, 2006, Retrieved from the Internet: Available Online@ 485

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