Scrambling is the result of regular randomizationcode。
AsModern communicationScrambling is one of the key technologies ofConfidentialityThe technology of randomizing the data to be transmitted at the bit layer.
Chinese name
Scrambling code
Foreign name
Scrambling
Interpretation
Signal code after regular randomization
Relevant fields
signal communication
Meaning
More suitable for baseband transmission, more secure
The identification method of scrambling code series is studied theoretically and verified by simulation, and the identification method of synchronous scrambling code series is improved to reduce the amount of data required by the algorithm and expand the application range of the algorithm for the source imbalance.[1]
Scrambling code classification
Announce
edit
According to the different LFSR synchronization modes of the transmitter and receiver, scrambling codes are divided into Frame Synchronous Scrambling (FSS), Distributed Sample Scrambling (DSS) and Self Synchronous Scrambling (SSS).
significance
Announce
edit
1. Reduce the length of connecting "0" or "1" to ensure that the receiver can extract the timing signal in place.
2. The scrambled signal spectrum is more suitable for baseband transmission.
3. Confidential communication needs.
objective
Announce
edit
The purpose of scrambling code is to suppress the long connection "0" and long connection "1" in the line code, so as to extract the clock signal from the line signal.Since the line signal only passes through scrambling code, the line signal rate of SDH is consistent with the standard signal rate of SDH electrical port, so the optical power cost of the transmitter laser will not be increased.
In addition, scrambling code can also distinguish different terminals or base stations. At the same time, scrambling code can also help improve the confidentiality of communication.Scrambling does not change the bandwidth of the signal, but only distinguishes the signals from different sources.In this way, even if multiple transmitters use the same codeword for spread spectrum, there will be no problem.
The relationship between spread spectrum and scrambling is shown in Figure 1.
Figure 1 Relationship between spread spectrum and scrambling
In actual operation, the information generated by the sourceBinary digitThe original information can be changed into another unintelligible sequence by adding the information to the module 2 of a long period pseudo-random sequence.Add (module 2 plus) the same at the receiving endPseudo-random sequence, the original message can be restored.
IMEI code
Announce
edit
IMEI code isInternational mobile device ID codeThe abbreviation of is composed of 15 digits. It corresponds to each mobile phone one by one, and the code is unique in the world.Each mobile phone will be given a unique IMEI code after assembly. This number will be recorded by the mobile phone manufacturer from production to delivery. It will not be recorded by the telecommunications company until the mobile phone is purchased by the user and logged into the network through the SIM card.The first six digits (TAC) of IMEI is the "model approval number", which generally represents the model, the next two digits (FAC) are the "final assembly number", which generally represents the origin, and the next six digits (SNR) are the "serial number", which generally represents the production sequence number.The last 1 digit (SP) is usually ''0' ', which is the inspection code for temporary use.The IMEI code is pasted on the sign on the back of the phone and read and written in the phone memory. It is the "file" and "ID card number" of the phone in the manufacturer, so it has certain verification value.[2]
Mobile phone scrambling code
Announce
edit
Access LicenseIt belongs to the quality mark, and is not affixed with the network access mark or affixed with the fake network access markmobile phoneIt shall not be sold in the market, nor be allowed to access the telecommunication network.
There are two types of access signs: one isAccess permission sign, one isOnline trial sign。Among them, the access permit sign is light blue, and the access trial sign is green.
The access permit sign is composed of 12 digits in the form of xx xxxx xxxxxx, where the third to sixth digits are the manufacturer's code,the republic of koreaSamsungThe original code is 1628, and Tianjin Samsung 5827.fromAccess LicenseWe can judge the origin of the mobile phone, South Korea orTianjin。
Network access license is also OKSmuggled goodsOne of the important bases for mobile phone identification.Consumers can useMoney verification lampIlluminate the access license. The real access license is at the lower right of the sign. You can see the red fluorescent cmii letters (the abbreviation of the Ministry of Information Industry) and an unclear number.In addition, you can also see a fluorescent vertical line on it, which gives you an obvious concave convex feeling when you touch it with your hand.
In addition to Zhengxing mobile phones, ShuixingBank of Hong KongandWater reformNo mobile phoneAccess License, even if there is one, it is a fake -- a fake certificate printed by an ordinary printer.Parallel mobile phonesIt is slightly different from the genuine online sign: the real online sign is generallyNeedle printerPrinted, the background pattern is light blue,typefaceIt is boldface, the strokes are slightly thick, and the color is dark. There is no reflection from any angle when looking at the light, and the numbers are clear. Look carefully at the dents with needles;Fake access signs are generally commonInk jet printerThe background pattern is printed in dark blue, generallyTahomaThe strokes are thin, reflective, the numbers are not very clear, there are burrs, and there are no dents.
