Upper Bound on the Performance of Subscriber Access Networks for Downstream Traffic Considerations for Broadband Applications

Increased demand for bandwidth arises from a proliferation of applications such as voice, video and data traffic as well as by the bootstrapping effect of increased consumption resulting from lower rates and optical fiber enjoys monopoly in providing long distance communication with a remarkable error rate performance. Optical communication is driven by WDM technology that employs Erbium Doped Fiber Amplifiers. WDM carves up the huge bandwidth of single mode fiber (SMF) into channels whose bandwidths are compatible with peak electronic processing speeds. The thesis deals only with the unidirectional aspect of the Dual Bus Architecture for Subscriber Access Network with passive optical splitting being employed at the Optical Network Unit (ONU). The aim is to give an upper bound on the number of WDM channels that can be transmitted and the number of subscribers that can be accommodated (by maximizing the number of power splits) for broadcast applications. The receiver sensitivity is compared for different detection schemes. Three cases arise as (i) Analog broadcast channels along with unicast transmission (also called switched services) (ii) Digital broadcast channels with switched services (iii) Hybrid Multichannel case. The analog broadcast is AM-VSB (Vestigial Side Band) and digital broadcast is M-QAM or QPSK modulated and they are sub-carrier multiplexed. The thesis also analyses the benefit of AM/OFDM than AM/M-QAM hybrid service in terms of bit error rate performance and proposes other schemes like Forward Error Correction coding. The simplified gain model of EDFA as a preamplifier has been adopted to exemplify its application in optical communication, and algorithm is given for the design of Subscriber Access Network, with an example design also carried out. Thus, the Wavelength Division Multiplexing (WDM) also called, as “Data in a Rainbow” concept will cater to the eventual needs of greater capacity and faster access.