Ingress noise cancellation for the upstream channel in broadband cable access systems

We present a receiver architecture for transmission over the upstream channel of hybrid fiber coax (HFC) networks affected by ingress noise and channel distortion. The receiver uses a noise prediction algorithm. It is shown that the proposed receiver makes it possible to transmit a QPSK signal over a cable channel affected by three interferers with an individual power of -10 dBc, with an SNR degradation of only 1.8 dB. The SNR degradation corresponding to 16-QAM transmission over a channel affected by three interferers of -15 dBc is 2.1 dB. We also describe an adaptation technique that makes use of empty time slots to track changes of the ingress noise continuously. The noise canceller involves only a small additional complexity.