PART II: Broadband Access Technologies: Myths & Reality

摘要

Bit rotes and symmetry - PON bit rates at the home are limited by the TDM nature of the backbone signals. A typical BPON downstream bit rate of 622 Mb/s or 155 Mb/s becomes about 19 Mb/s or about 5 Mb/s downstream to the home for a split of 32:1. With MPEG2 HDTV bandwidth requiring about 20 Mb/s for each channel, BPON digital bandwidth is insufficient, hence an RF overlay on another downstream wavelength is necessary for video signals (see video services below for RF overlay issues).