Patent ID: 8311217

Claim:
A data transmission method applied to a point-to-multipoint Coaxial-cable Network, wherein the point-to-multipoint Coaxial-cable Network comprises a Coaxial-cable Line Terminal, CLT, and a plurality of Coaxial-Cable Network Units, CNUs; the CLT shares transmission medium with the CNUs, the method comprises: obtaining, by the CLT, an uplink receiving scrambling code used by a CNU, and decrypting, by the CLT, with the obtained uplink receiving scrambling code used by the CNU, data sent from the CNU after being encrypted with the uplink transmission scrambling code used by the CNU; and obtaining, by the CNU, a downlink receiving scrambling code used by the CNU, receiving data which is sent from the CLT and encrypted with a downlink transmission scrambling code used by the CNU and data which is sent from another CNU and encrypted with an uplink transmission scrambling code used by the another CNU and decrypting, by the CNU, data received by the CNU with the obtained downlink receiving scrambling code used by the CNU; wherein the uplink receiving scrambling code used by the another CNU is different from the downlink receiving scrambling code used by the CNU.