APPARATUS AND METHOD FOR A DYNAMIC ALLOCATION OF DATA RATE AND ADAPTIVE MODULATION CONTROL IN CABLE SYSTEM OF USING MULTI-CARRIER DEMODULATION

摘要

PURPOSE: An apparatus and method for dynamically allocating a data rate and an adaptive modulation method and apparatus in a cable system using multi-carrier modulation and demodulation are provided to respectively allocate many bits and little bits through a sub channel having a large SNR and the sub channel having a small SNR by using different SNR information. CONSTITUTION: A headend estimates a SNR(Signal-Noise Ratio) of each sub channel signal received through an upstream receiving part(410). The SNR per the sub channel is estimated from the output of a symbol demapper. The headend estimates the SNR per the sub channel. A channel capacity of each sub channel which can be transmitted is calculated based on the SNR of the each estimated sub channel(420). The headend calculates the channel capacity of each sub channel which can be transmitted. The headend assigns the number of bits per the sub channel based on the calculated channel capacity which can be transmitted. The headend transmits an UCD(Upstream Channel Descriptor)_change message to a cable modem(430).