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In recent years, with the rapid development of the telecommunications network , the access network gradually become a bottleneck for further enhancement of the constraints of the network speed . In order to meet the demand for broadband access , new access network technologies continue to emerge. Current access network technology based on metal cable xDSL technology , based on the the HFC Cable Modem technology , based on five twisted pair Ethernet access technology , as well as fiber access technology and broadband wireless access technology . The fiber access high bandwidth, transmission distance , confidentiality , etc. , is the mainstream technology for future broadband access networks . Among them, the passive optical network ( PON ) with its low-cost , simple networking , easy to upgrade and expansion characteristics , optical networks become a major concern . PON experience to by APON, BPON , EPON and GPON course of development . GPON has a high rate to support a full-service , high efficiency , provides carrier-class QoS guarantee , is ideal for broadband optical access network technology . GPON technology features mainly reflected in the transmission convergence layer , ie GTC layer . GPON core technologies, including framing and adaptation of the uplink and downlink , ranging and delay compensation , dynamic bandwidth allocation , encryption and decryption and error control are implemented in the layer . Therefore , the research and design of the GPON GTC layer is of great significance for the achievement of the GPON . This paper first introduces several major access network technology analysis and comparison of difference between GPON APON , EPON , etc. , explains the advantages of GPON technology ; followed by a brief introduction the GPON standard system and the overall hierarchical model , focusing on the GTC layer of the protocol stack, the layered structure , the layers of the key features and requirements ; then, on the basis of the analysis of the the GPON uplink and downlink frame structure , the design of each functional module of the uplink and downlink , wherein the NRZ code , CRC8 , BIP8, RS, AES encryption and decryption coding theory and implementation ; and analysis of the shortcomings and deficiencies of several major dynamic bandwidth allocation algorithm , dynamic bandwidth allocation algorithm based on the T-CONT priority and bandwidth demand ; Finally , Verilog hardware description language of the relevant module description of each module simulation , Xilinx ISE software platform ; given the overall simulation results of uplink and downlink processing and DBA algorithm . This article is a useful attempt GPON key technology and exploration .
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