As VoIP (Voice over IP) and HSD (high speed data) penetration increases, more bandwidth is needed in the upstream.

• 由于VoIP(Voice over IP),和HSD(high speed data)的快速发展,在反向通道里需要更宽的信号带宽。 在一定的回传频率宽度内,高效的调制方式会增加信号带宽。