Study On The Resource Management In Next Generation Ethernet Passive Optical Networks(Ng-Epon)

Passive optical networks(PONs),owing to their high capacity and coverage potential,are becoming prominent and promising solution for various applications of access networks.The rapid increase in number of internet consumers around the globe and the demand for high-speed data services has excited the operators to deploy multi-Gb/s network facilities to meet the corresponding demands.To support this increasing demand for high-speed data services,IEEE and ITU-T are working to standardize NG-EPON(100G-EPON)and XGS-PON respectively.Specifically,NG-EPON has a huge potential to support emerging 5G technologies with its capacity to carry 100 Gb/s data.NG-EPON would support 4 wavelengths with an individual capacity of 25 Gb/s,where an ONU can transmit simultaneously on any number of wavelengths in the system.NG-EPON,due to its provision of transmission on multiple wavelengths,opened a new dimension of research in bandwidth resource management to address new issues e.g.efficient resource utilization,how many and which wavelengths to be assigned to an ONU in a grant and solution for frame resequencing problem etc.Therefore,efficient bandwidth and wavelength resource management schemes are required in NG-EPON.Our research study provides two new DBAs to address two different problems in NG-EPON: 1)Solution for frame resequencing problem,and 2)solution for transmission on flexible number of wavelengths.The objective of our first DBA is to provide a solution of resequencing problem with low latency,better grant and channel utilization,low jitter,and low packet drop ratio in the network.The objective of our second DBA is to provide a solution for bandwidth resource management on flexible number of wavelengths with low latency,better grant utilization,and low jitter in the network.To solve the above-defined problems,the detailed work is as follows:1.Solution for Resequencing Problem with low latency in NG-EPONEthernet frames are of different size and are non-fragmentable.Therefore,in NG-EPON,there are two challenges in the design of an optimal DBA.Firstly,when a grant to an ONU is given on multiple wavelengths in each cycle,it is quite possible that some of the granted bandwidth portion is left unused due to the random frame size,and the last few frames may be denied to be transmitted because of non-fragmentability of Ethernet frames as the given grant on multiple wavelengths may not accommodate integer number of Ethernet frames,which is called frame-size mismatching problem.Secondly,when a grant to an ONU is given on multiple wavelengths,it is quite possible that frames' transmission start time and completion time is different from each other due to transmission on multiple wavelengths.It is also possible that each wavelength availability or start time is different from other wavelengths.These both factors will create a possibility that later transmitted frames from ONU to OLT reach OLT before earlier transmitted frames.Therefore,these out of sequence reached frames may have to wait for earlier frames before any further processing at the OLT.This will result in resequencing problem,which will require additional processing and buffer storage at OLT for each transmission from every ONU in the network.We provided a solution to cater frame resequencing problem.The proposed DBA is named as first-fit DBA(FF-DBA)and the performance is evaluated in comparison with IPACT and recently proposed water-filling principle based DBA(water-filling DBA).Simulation experiments were performed to evaluate the performance and the experimental results show that our provided solution(FF-DBA)is giving low latency,better grant and channel utilization,low jitter and low packet drop ratio at any offered load.2.Flexible Resource Management with low latency in NG-EPONBased on the outcomes of our first solution,we proposed another DBA to assign flexible number of wavelengths and grant size on each selected wavelength,to each ONU in a single grant to provide flexible solution for any kind of NG-EPON network with any number of ONUs in the network.When there are very few ONUs in the network and each one is generating very high data traffic,then FF-DBA,which is providing zero resequencing delay,will not remain effective in proving low latency.Therefore,we provided another solution for such kind of scenarios,where number of ONUs and their generated traffic could be very different.We named this DBA as flexible wavelength and dynamic bandwidth allocation(FW-DBA).An optimal parameter,named alpha,is used while deciding number of wavelengths to be used in grant allocation process.The performance of the proposed FW-DBA is evaluated in comparison with our proposed First-Fit DBA(FF-DBA),IPACT and water-filling DBA.Simulation experiments were conducted to evaluate the performance and the experimental results show that our provided solution(FW-DBA)is giving low latency,better grant utilization,low jitter,and is using flexible number of wavelengths for each ONU grant based on the reported bandwidth requirements at any offered load.Another series of experiments is conducted to evaluate which value of alpha will give optimal solution for different number of ONUs in the network,and a relation is derived between alpha and number of ONUs in the network.Our both solutions are providing low latency solution for NG-EPON with their own advantageous domain.FW-DBA also validates our first solution,FF-DBA,when there is large number of ONUs in the network.We also suggest future research directions of our research work that can be used to create more sophisticated and comprehensive models to facilitate the development of more advanced DBA algorithms.