CN110149139A - A kind of compression transmitting method of Big Dipper short message - Google Patents
A kind of compression transmitting method of Big Dipper short message Download PDFInfo
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- CN110149139A CN110149139A CN201910413080.6A CN201910413080A CN110149139A CN 110149139 A CN110149139 A CN 110149139A CN 201910413080 A CN201910413080 A CN 201910413080A CN 110149139 A CN110149139 A CN 110149139A
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- short message
- big dipper
- compression
- dipper short
- algorithm
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03M—CODING; DECODING; CODE CONVERSION IN GENERAL
- H03M7/00—Conversion of a code where information is represented by a given sequence or number of digits to a code where the same, similar or subset of information is represented by a different sequence or number of digits
- H03M7/30—Compression; Expansion; Suppression of unnecessary data, e.g. redundancy reduction
- H03M7/3084—Compression; Expansion; Suppression of unnecessary data, e.g. redundancy reduction using adaptive string matching, e.g. the Lempel-Ziv method
- H03M7/3088—Compression; Expansion; Suppression of unnecessary data, e.g. redundancy reduction using adaptive string matching, e.g. the Lempel-Ziv method employing the use of a dictionary, e.g. LZ78
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B7/00—Radio transmission systems, i.e. using radiation field
- H04B7/14—Relay systems
- H04B7/15—Active relay systems
- H04B7/185—Space-based or airborne stations; Stations for satellite systems
- H04B7/1851—Systems using a satellite or space-based relay
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B7/00—Radio transmission systems, i.e. using radiation field
- H04B7/14—Relay systems
- H04B7/15—Active relay systems
- H04B7/185—Space-based or airborne stations; Stations for satellite systems
- H04B7/1851—Systems using a satellite or space-based relay
- H04B7/18517—Transmission equipment in earth stations
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- Physics & Mathematics (AREA)
- Astronomy & Astrophysics (AREA)
- Aviation & Aerospace Engineering (AREA)
- General Physics & Mathematics (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Theoretical Computer Science (AREA)
- Compression, Expansion, Code Conversion, And Decoders (AREA)
Abstract
The invention discloses a kind of compression transmitting methods of Big Dipper short message, it effectively combines the lzw algorithm (Lempel-Ziv-Welch Encoding) in LZ series coding with Chinese Word Automatic Segmentation, according to Chinese use habit, the problem of construction is suitable for the dictionary for word segmentation of Big Dipper short message, and this method overcomes the length limited that Big Dipper short message occurs in transmission process to a certain extent.
Description
Technical field
The invention belongs to compression coding technology field in digital communication more particularly to a kind of compression transmissions of Big Dipper short message
Method.
Background technique
Chinese Beidou satellite navigation system is the Global Satellite Navigation System that China voluntarily develops.It is to be positioned after US Global
The satellite navigation system of third maturation after system (GPS), Russian Glonass satellite navigation system (GLONASS).System
System can round-the-clock in the world, round-the-clock be all types of user provide high-precision, it is highly reliable positioning, navigate, time service service, and
With short message communication capacity.Big Dipper short message communication is the featured function of dipper system, can be subscriber computer and subscriber computer, user
The communication service of 120 Chinese characters is at most provided every time between machine and ground central station.But as practical application, the limitation of capacity is not
It is sufficient for the demand of reality.Therefore, it is necessary to combine the actual conditions of dipper system, a kind of data compression scheme is designed, that is, is existed
Within the scope of limited message length, warning message is compressed as far as possible, conveys more letters with identical character quantity
Breath, and reconfiguration information is identical with original information, i.e., lossless data compression.
Chinese word segmentation is the first step to Big Dipper short message compression processing, and traditional compression algorithm is to the north based on Chinese
The short message compression effectiveness that struggles against is unobvious, therefore we convert Numerical Index code for Big Dipper short message first with Chinese word segmentation,
Then compression processing is carried out again.Currently, common Chinese word cutting method includes: segmenting method based on dictionary, based on understanding
Segmenting method and segmenting method based on statistics.Segmenting method based on dictionary is most widely used Chinese word cutting method, it
It is divided into again: Forward Maximum Method method, reverse maximum matching method and bi-directional matching method.Forward Maximum Method algorithm refers to from left to right
By wait segment several continuation characters and dictionary matching in text, if matched, it is syncopated as a word.Reverse maximum matching
Algorithm is the reverse thinking of Forward Maximum Method, goes to match by entire character string to be slit first, if matching not at
Function then falls the most previous word of matching field, is recycled to entire sentence cutting always and finishes.Bi-directional matching algorithm is the two
In conjunction with the cutting result of the two being compared, to select optimal solution.According to SunM.S. and Benjamin K.T.'s (1995)
Studies have shown that 90.0% or so sentence, two kinds of matching methods are completely coincident and correctly, and two kinds of sentence of only general 9.0% are cut
The result that point method obtains is different, but it is correct for must wherein having one.It can be seen that bi-directional matching algorithm cuts Chinese
Divide accuracy higher.Therefore, the Chinese segment method that computation complexity is low, algorithm accuracy is high, has a wide range of application has important
Research significance and application value.
It is exactly by dynamically establishing a string table, the shorter code of use that lzw algorithm, which is called " string list compression algorithm ",
Come indicate longer character string realize compression, lzw algorithm is a kind of lossless compression algorithm.Lzw algorithm can efficiently use character
Frequency of occurrences redundancy is compressed, and dictionary is adaptive generation, it has the characteristics that below several: LZW compress technique
The data little for predictability have good treatment effect, commonly use the compression of images with TJF format；For in data flow
The byte and word string for continuously repeating appearance have very high compression ratio；LZW compress technique is also used for the data compressions such as text application
Field；Common ARC, RKARC, PKZIP Efficient Compression program is all the variant of LZW compress technique；For any width and picture
The image of plain bit length all has stable compression process；It is of less demanding to machine hardware, on the machine of Intel 80386
It can carry out compression and decompression.
Summary of the invention
The purpose of the invention is to overcome the problems, such as Big Dipper short message, there are length limiteds in communication process, propose one
The compression transmitting method of kind Big Dipper short message.
The technical solution adopted by the present invention are as follows:
A kind of compression transmitting method of Big Dipper short message, includes the following steps:
Step 1, the dedicated vocabulary of statistical correlation writes Beidou everyday words dictionary, and assigns index code for each vocabulary；
It step 2, is reference with the Beidou everyday words dictionary that writes, using Chinese Word Automatic Segmentation by Big Dipper short message cutting
At k phrase；K≤M, M are the number of characters of Big Dipper short message；
Step 3, respective Numerical Index code is converted according to Beidou everyday words dictionary by the phrase segmented；
Step 4, using lzw algorithm, Numerical Index code character obtained in step 3 is subjected to second-compressed, obtains compressing short
Message；
Complete the compression processing to Big Dipper short message.
Wherein, the Chinese Word Automatic Segmentation in step 2 specifically: bi-directional matching algorithm is used, by positive maximum
It is compared with algorithm with reverse maximum matching algorithm result, obtains optimal solution.
Wherein, the vocabulary in dictionary that lzw algorithm is established in real time in step 4 has prefix, the phrase quilt of same prefix
Combination distributes new number.
The present invention is acquired compared with prior art to be had the beneficial effect that
A kind of compression transmitting method of Big Dipper short message proposed by the present invention, this method computation complexity is low, to Chinese
Based on Big Dipper short message have good compression performance.And according to the characteristic of LZW compression algorithm, this method, which has, to be repeated
The characteristics of vocabulary is more, and compression effectiveness is more obvious.
Detailed description of the invention
Fig. 1 is a kind of compression transmission flow chart of Big Dipper short message of the present invention；
Fig. 2 is the dictionary model figure of the Chinese Word Automatic Segmentation based on dictionary in the present invention；
Fig. 3 is LZW compression algorithm work flow diagram in the specific embodiment of the invention.
Specific embodiment
Objects and advantages in order to better illustrate the present invention, 1-3 and embodiment are to skill of the invention with reference to the accompanying drawing
Art scheme is described further.In this embodiment, following short message information will be used to describe as example:
Short message []={ s1s2s3s4s5s6s7s4s5s6s7}
Big Dipper short message once can only at most transmit 120 characters in communication process, in order to clearly describe algorithm work
Make principle, chooses 11 characters as compression goal.And according to compression algorithm characteristic, there are repeat character (RPT)s in target to be compressed
s4s5s6s7。
In order to describe the needs of algorithm, further reduce the scale of problem, it is assumed that Forward Maximum Method algorithm and it is reverse most
Big matching algorithm result is identical, and algorithm description is carried out using Forward Maximum Method algorithm as example, problem scale diminution and
The demonstration program of this example is not influenced, and Big Dipper short message compression transmission process is as shown in Figure 1.
A kind of compression transmitting method of Big Dipper short message, the Big Dipper short message to be compressed are as follows: short message
[]={ s1s2s3s4s5s6s7s4s5s6s7, include the following steps:
Step 1, the dedicated vocabulary of statistical correlation writes Beidou everyday words dictionary, and assigns index code for each vocabulary；
Step 2, according to the process sequence of Fig. 1, short message to be compressed is subjected to Chinese word segmentation processing first, it is assumed that participle institute
The dictionary of reference are as follows:
Dic []={ " s1s2”“s1s2s3”“s4s5”“s6s7”}
By taking Forward Maximum Method algorithm as an example, short message to be slit is scanned from left to right, scanning to s1s2It is the discovery that
Word in dictionary, but cannot determine whether to continue to scan on for maximum vocabulary, find s1s2s3It is the word in dictionary, does not can determine that still
It whether is maximum vocabulary, until scanning is to the end, determination is syncopated as first word s1s2s3.It continues to scan on, until entire short message
It is split as following phrase:
Word []={ s1s2s3 s4s5 s6s7 s4s5 s6s7}
Step 3, the phrase segmented is converted into respective index code；
The phrase that will have been segmented is converted to respective Numerical Index code shape according to transformation rule as shown in Figure 2
Formula, phrase will be converted into following form (inFor index code of the vocabulary in dictionary):
Word []={ ic ia ib ia ib}
Step 4, second-compressed is carried out to index code character using lzw algorithm；
The index code character that step 3 is generated is according to carry out second-compressed processing as shown in Figure 3, and lzw algorithm is to be compressed
Phrase is scanned, and dynamically establishes phrase table, in scanning process, by prefix (ia ib) typing dictionary, it is to be scanned to next
(ia ib) find that the prefix is already present in dictionary, use new number (n+1) (n is by the number of word in dictionary) to replace, directly
It is finished to compression, index code character is compressed into following form:
Code []={ ic ia ib (n+1)}
So far, the process of Big Dipper short message compressed encoding is terminated.
Lzw algorithm will dynamically establish dictionary, and the vocabulary in dictionary has the property that
(the already present prefix of dictionary in ω expression)
Through lzw algorithm second-compressed, following compression short message is obtained:
Msg (A)=A1/A2/.../AN,(N≤k)
It is the concrete analysis compression method to the compression effectiveness of Big Dipper short message, chooses the alarm message of different length,
And it is divided into: 10 word groups, 20 word groups, 50 word groups, 100 word groups, 120 word groups, 150 word groups and 200 word groups.Every group of selection 5 alarms
Segment carries out coding compression, and every group of compressed average number of words and compression ratio is asked (to compress short message after preceding message number of words/compression
Average number of words), and record data.The results are shown in Table 1, it can be seen that new method has good compression to imitate Big Dipper short message
Fruit.Test allocation of computer used are as follows: Intel Core 3.30GHz processor, 8GB memory, Matlab R2016a software are flat
Platform.
1 Big Dipper short message compression transmission experimental result of table
| Short message number of words before compressing | Short message average number of words after compression | Compression ratio |
| 10 word groups | 9.4 | 1.064 |
| 20 word groups | 18.6 | 1.075 |
| 50 word groups | 46.4 | 1.078 |
| 100 word groups | 92.4 | 1.082 |
| 120 word groups | 110.8 | 1.083 |
| 150 word groups | 138.2 | 1.085 |
Although the embodiments of the invention are described in conjunction with the attached drawings, it will be apparent to those skilled in the art that not taking off
Under the premise of from the principle of the invention, various modifications and improvements can be made, these also should be regarded as belonging to protection model of the invention
It encloses.
Claims (3)
1. a kind of compression transmitting method of Big Dipper short message, it is characterised in that include the following steps:
Step 1, the dedicated vocabulary of statistical correlation writes Beidou everyday words dictionary, and assigns index code for each vocabulary；
Step 2, it is reference with the Beidou everyday words dictionary write, Big Dipper short message is cut into k using Chinese Word Automatic Segmentation
A phrase；K≤M, M are the number of characters of Big Dipper short message；
Step 3, respective Numerical Index code is converted according to Beidou everyday words dictionary by the phrase segmented；
Step 4, using lzw algorithm, Numerical Index code character obtained in step 3 is subjected to second-compressed, obtains compression short message；
Complete the compression processing to Big Dipper short message.
2. a kind of compression transmitting method of Big Dipper short message according to claim 1, it is characterised in that: the institute in step 2
The Chinese Word Automatic Segmentation stated specifically: bi-directional matching algorithm is used, by Forward Maximum Method algorithm and reverse maximum matching algorithm
As a result it is compared, obtains optimal solution.
3. a kind of compression transmitting method of Big Dipper short message according to claim 1, it is characterised in that: LZW is calculated in step 4
The vocabulary in dictionary that method is established in real time has prefix, and the phrase of same prefix, which is combined, distributes new number.
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Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107561564A (en) * | 2017-09-08 | 2018-01-09 | 广州祺智通信科技股份有限公司 | A kind of compression implementation method of big-dipper satellite information transfer |
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Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107561564A (en) * | 2017-09-08 | 2018-01-09 | 广州祺智通信科技股份有限公司 | A kind of compression implementation method of big-dipper satellite information transfer |
Non-Patent Citations (1)
| Title |
|---|
| 彭皓: "北斗系统用户通信数据扩容技术研究", <<中国优秀硕士学位论文全文数据库>> * |
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Application publication date: 20190820 |