TDMA-based OLT sharing method to improve disaster tolerance in Elastic Lambda Aggregation Network

Abstract

To improve disaster tolerance in optical access and aggregation network, Elastic Lambda Aggregation Network (EλAN) has been proposed. This paper proposes a novel TDMA based OLT sharing method among ONU groups in EλAN. Introduction A fiber to the home (FTTH) is widely used as an access network. A passive optical network (PON) that realizes FTTH shares a trunk fiber between an optical line terminal (OLT) and optical network units (ONUs). A failure in a trunk fiber leads service interruption in multi-lines. In order to solve this problem, A PON protection method that sets up a backup system and duplicates the route is standardized in ITU-T G.983. However, the PON protection is not good enough to recover the failure. For example, in March 2011, by the Great East Japan Earthquake, many central offices (COs) were collapsed by the tsunami and redundant fiber routes were broken. Therefore, a new disaster recovery method that provides higher availability than the protection method should be developed. In 2012, research and development of Elastic Lambda Aggregation Network (EλAN) has started. EλAN will integrate access and metro/aggregation networks using an optical distribution network (ODN) and longer-transmission-capable OLTs/ONUs. This means that EλAN provides restoration capability from the OLT to ONUs. In this paper, to enhance the network availability, a novel time division multiple access (TDMA) based OLT sharing method among ONU groups is proposed. The proposed method provides exceeding the ONU accommodation limit number of single OLT. The prototype implementation and performance evaluation results are present.