What is scrambling code

Scrambling code is a signal code that has been regularly randomized; as one of the key technologies of modern communications, scrambling code is required at the bit layer in order to improve the timing recovery capability and confidentiality of transmitted data. Technology for randomizing the transmitted data; conducted theoretical research and simulation verification on the identification method of scrambling code series, and improved the identification method of synchronous scrambling code series, which not only reduces the amount of data required by the algorithm, but also expands the This shows the applicability of the algorithm to source imbalance.

#The operating environment of this tutorial: Windows 10 system, Dell G3 computer.

What is scrambling code?

The scrambling code is the signal code after regular randomization.

As one of the key technologies of modern communications, scrambling is a technology that randomizes the data to be transmitted at the bit layer in order to improve the timing recovery capability and confidentiality of transmitted data.

Conducted theoretical research and simulation verification on the identification method of scrambling code series, and improved the identification method of synchronous scrambling code series. While reducing the amount of data required by the algorithm, it also expanded the algorithm's ability to The scope of application of source imbalance.

According to the different LFSR synchronization methods of the sending and receiving parties, scrambling codes are divided into Frame Synchronous Scrambling (FSS), Distributed Sample Scrambling (DSS) and Self Synchronous scrambling. Scrambling, SSS).

The meaning of scrambling code

1. Reduce the length of consecutive "0" or consecutive "1" to ensure that the receiver can extract the timing signal in place.

2. Make the scrambled signal spectrum more suitable for baseband transmission.

3. Confidential communication needs.

Figure 1

The purpose of the scrambling code is to suppress the long consecutive "0" and long consecutive "1" in the line code, so as to facilitate the Extract the clock signal from the line signal. Since the line signal only passes through the scrambling code, the SDH line signal rate is consistent with the SDH electrical port standard signal rate, which does not increase the optical power cost of the transmitter laser.

In addition, scrambling codes can also distinguish different terminals or base stations. At the same time, scrambling codes can also help improve the confidentiality of communications. Scrambling does not change the bandwidth of the signal, but only separates signals from different sources. In this way, there will be no problem even if multiple transmitters use the same codeword to spread spectrum.

The relationship between spreading and scrambling is shown in Figure 1.

In actual operation, generally adding the binary digital information generated by the source and a long-period pseudo-random sequence modulo 2 can turn the original information into another incomprehensible sequence. By adding (modulo 2) the same pseudo-random sequence at the receiving end, the original sent information can be restored.

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