As interactive services require more bandwidth, high speed access networks must follow this trend. Although a Hybrid Fiber Coax (HFC) system provides a large bandwidth, many problems occur due to the accumulation of the ingress and impulse noise. In this paper the properties of the ingress and impulse noise will be explained based on a measurement campaign on different networks.The most striking result of the measurement campaign is the large dynamic and time-dependent behavior of the ingress noise. This dynamic behavior is an important factor in designing an upstream communication system. We show that for this reason optimized receivers will contain adaptive equalizers. This is illustrated by the performance analysis of a TDMA and an OFDM-CDMA system. Both systems are compared under the same environment. The results of this comparison shows how both can obtain the same performance.Considering the implications of both the TDMA and the CDMA system when using an equalizer in the head-end receiver, requirements for a total HFC network architecture are given. Especially synchronization and initialization issues must be addressed.

This paper deals with the derivation and comparison of some promising TDMA and OFDM/CDMA receiver structures for communication over the return path channel of the cable TV (CATV) network. Regarding TDMA, it is shown that the performance substantially improves by using equalization. Given the slowly varying, frequency selective nature of the ingress noise, OFDM seems an interesting possible access technique to employ. Here it is considered in combination with CDMA. With respect to the performance in terms of SNR at the input of the decision device, the TDMA structure gives better results than the OFDM/CDMA schemes. Also with respect to design complexity TDMA seems more interesting.