The present document describes cost effective and flexible access networks using optical fibre technology. The present document is designed to provide both services to meet the current demands and an infrastructure@ which is able to satisfy the requirements of the future. The present document describes the characteristics of an Optical Access Network (OAN) with the capability of transporting interactive services@ based on 64 kbit/s bearer capabilities@ between the User Network Interface (UNI) and the local exchange. The present document considers an OAN capable of providing business and residential customers with a range of services (up to 2 Mbit/s) over a passive split optical network. Distributive services (e.g. cable television) are outside the scope of the present document. The OAN described in the present document has considered the requirement for the access network to adapt to the changing requirements of individual customers in terms of capacity@ flexibility and types of services offered without the need for network operators to provide service specific overlay networks. The considered systems within the present document are based on Time Division Multiple Access (TDMA) and/or Subcarrier Multiple Access (SCMA) methods. One and two fibre systems are described. The present document considers OANs where the Optical Distribution Network (ODN) is based on point-to-multipoint tree and branch options as described in ETS 300 681 [4]. The present document is not a complete system definition. It identifies aspects that can be defined without preventing transmission innovation.