LRC-PON System Architecture And QoS Enhancement Technology Research

With the rapid development of WDM-PON and OFDM-PON,while enjoying the advantage of the passive optical network(PON)technology,the users' requirements for quality of service(QoS)is higher and higher.For some special application scenarios,especially when considering uneven distribution of users within a geographical region,the current PON system architecture cannot effectively meet the requirements of QoS.Due to the phenomenon that high cost is needed for sending and receiving optical OFDM signal,and meanwhile increasing transmission power leads to high energy consumption,these all enhance the cost for network.The critical factor for the next.generation access network is how to guarantee the QoS with lower cost.So in this paper we propose a LRC-PON(Long-Reach Cluster PON).We have used DBA algorithm with consideration of energy consumption Ec,delay,and required bandwidth(AMF_EDC)for the uplink transmission.Meanwhile transmit traffic in advance and queuing mechanism improvement are applied to increase QoS.By combining the national 863 plan project and national natural science funds,we do some research on LRC-PON and QoS enhancement technology.Firstly,for the phenomenon that uneven distribution of users within a geographical region,in this paper a LRC-PON is proposed.According to the geographical region,the users are assigned to different clusters.Because service scope of each cluster is different,LRC-PON is designed based on the distribution characteristics of users.Meanwhile the service scope and numbers of designed cluster are also decided by the actual situation.Secondly,in order to improve the QoS for LRC-PON system architecture,in this paper we not only take allocation for both time slot and frequency,but also combine with physical layer and medium access control layer,we propose adaptive modulation format mechanism(AMF_EDC)with consideration of energy consumption,delay and required bandwidth,and dynamic bandwidth allocation algorithm based on AMF EDC.Finally,the effectiveness for enhancement QoS has been proved by simulation.Thirdly,in order to increase the efficiency of traffic which is transmitted in long distance,we propose the method that transmiting the traffic in advance based on priority,for example the highest service level traffic for next period will be transmitted in the current period,and part of the second priority traffic will be transmitted in the idle time.The simulation results show that the idle time is applied efficiently,the QoS of highest priority traffic and the second level traffic is improved.Fourthly,in view of QoS guarantee,we propose method of queue mechanism enhancement based on service priority,according to different service level,different queue method is applied.The simulation results show that the lost packets which are caused by full storage space have been reduced and packet blocking rate is decreased for the highest priority traffic.