Research On Performance Optimization Of WDM-OFDM Broadband Optical Access Network

In recent years, with the rapid development of the Internet business,the number of end users is growing exponentially. How to improve the network bandwidth and make a reasonable distribution of network topology have become an urgent problem to be solved. Implementation of the "broadband China" and "optical fiber home" development strategy requires a high performance access network scheme to carry out technical support. Traditional time division multiplexing (TDM) technology has been unable to meet the needs of users bandwidth. New optical access network technology combined WDM and OFDM have received more and more attention. With the earth energy depleting, the importance of energy-saving emission reduction embodied in various industries, optical networks as the most important broadband information infrastructure,energy saving and emission reduction can not only reduce its carbon emissions, but also bring more space for energy saving and emission reduction of the whole communication network. Therefore, the research points of optical access network are focused on the topology, dynamic bandwidth allocation algorithm and energy saving.This paper relies on the National 863 project and National Natural Science Fund project,proposes a long-reach-grouped passive optical networks (LRC-PON) system structure of users geographically uneven distribution, and according to this kind of structure, considering the user quality of service(QoS) requirements and cost two factors, proposed scheme combined with time delay and energy consumption in order to achieve the purpose of access network energy saving. At the same time,the paper discusses the semi physical simulation scheme, analyzes and designs the interface structure of OPNET and external connection, and realizes the interconnection of OPNET software and Microsoft Visual Studio 2010.The main work and innovation points are as follows:(1) In order to solve the problem of increasing the number of passive optical networks (ONU) in optical terminal (OLT), a long-reach-grouped passive optical networks (LRC-PON) is proposed. In order to solve the problem that there are tidal effects in different regions of the same community, ONU is further grouped in the community.(2) Aiming at the problem of energy saving, two modes that sleeping between polling cycles (SBPC) and sleeping in polling cycle(SIPC) of ONU were designed. SBPC uses deep sleep technology ,mainly used in ONU that has very small business . SIPC uses fast sleep technology, mainly used in ONU that has a lot number of business. OLT determines which sleep mode ONU use according to the algorithm control mechanism.(3) A dynamic bandwidth allocation algorithm based on ONU sleep mechanism in LRG-PON structure is proposed and simulated. The proposed algorithm performs dynamic bandwidth allocation from multiple dimensions of time slot, wavelength and frequency gap, and considers ONU energy saving and business fairness simultaneously.(4) Aiming at the semi physical simulation problem of network mechanism, the interface between OPNET and external interconnection is designed, and the interconnection between OPNET software and Microsoft Visual Studio 2010 is realized.