A communication system based on Data Over Cable Service Interface Specification (DOCSIS) protocol, the communication system comprising:
- a server configured to send a signal and demodulate a received signal;
- a coaxial cable configured to transmit signals sent and received by the server through a coaxial cable network;
- a frequency divider connected to the coaxial cable, and configured to divide the signal sent by the server into a downstream signal and a full duplex signal;
- a downstream communication path configured to transmit the downstream signal sent by the server to a first modulation and demodulation unit;
- an upstream communication path configured to transmit an upstream signal sent by a second modulation and demodulation unit to the server;
- and
- a full duplex communication path configured to simultaneously transmit the downstream signal divided by the frequency divider and the upstream signal sent by the second modulation and demodulation unit, separate the downstream signal from the full duplex signal and transmit to the first modulation and demodulation unit, and transmit the upstream signal sent by the second modulation and demodulation unit to the server;
- wherein a bandwidth range of the full duplex communication path is 108 Mega Hertz (MHz)˜684 MHz, and the full duplex communication path comprises a primary filter path, a secondary filter path and a tertiary filter path:
- the primary filtering path comprises:
- a second low-pass filter electrically connected to the frequency divider, and configured for passing downstream signals with a bandwidth of 108 MHz˜684 MHz;
- a first synthesizer, a first input end of the first synthesizer being electrically connected to an output of the second low-pass filter, the first synthesizer being configured for removing the upstream signal in the full duplex signal leading to the first modulation and demodulation unit;
- a first Radio Frequency (RF) switch, a common end of the first RF switch being electrically connected to an output end of the first synthesizer, a first end of the first RF switch being electrically connected to the first modulation and demodulation unit, the first RF switch being configured for transmitting the downstream signal with the bandwidth of 108 MHz˜684 MHz to the first modulation and demodulation unit;
- a first phase regulator, an input end of the first phase regulator being electrically connected to the second modulation and demodulation unit, the first phase regulator being configured for phase adjustment of the upstream signal sent by the second modulation and demodulation unit;
- a second power amplifier, an input end of the second power amplifier being electrically connected to an output end of the first phase regulator, an output end of the second power amplifier being electrically connected to a second input end of the first synthesizer, the second power amplified being configured for adjusting a power of the phase adjusted signal and outputting a signal with an opposite phase and a same power as the upstream signal sent by the second modulation and demodulation unit;
- a system-on-a-chip electrically connected to the second power amplifier, and configured for controlling a magnification of the second power amplifier.