In this paper, we compare the major issues associated with TDMA and S-CDMA (Synchronous-Code Division Multiple Access), which is considered as a new cable modem standard technology for upstream channel. We mainly deal with the following 3 topics: MAC protocol, modem structure and BER (Bit Error Rate) performance comparison between TDMA and S-CDMA. Especially, we derive BER of TDMA and S-CDMA schemes in the ε-mixture impulse noise model which appropriately reflects impulse noise characteristics of the upstream channel by using various parameters.