Study On The Bandwidth Resource Management Scheme In Software Defined Optical Access Networks

Passive optical networks(PONs),as the "last mile" to connect users,is a critical part of the communication network.In recent years,with the rise of cloud storage/cloud computing,video broadcast,video conferencing,high-definition TV,online gaming,network file sharing,the total number and bandwidth requirement of broadband users grow explosively,driving the operators to depoly more network facilities to meet the corresponding demands.With the continuous expansion of optical access networks and the variety of network service requirements,every subject in the communication network,including operators,users and service providers,is facing challenges and problems.The massive deployment of PONs increases the operator's CAPEX(Captical Expense)& OPEX(Operation Expense),but the income increases less,resulting in ROI(Return on Investment)decline.The increase of access bandwidth does not enhance the quality of services(QoE)for users.The traditional PON is not open enough for service providers to schedule bandwidth resource and effectively guarantee user QoE,and meet requirements of various customers.Therefore,in order to take these advantages of SDN,such as simplifying network management and enableing programmable network,many researchers try to apply SDN into PONs to realize efficient,flexible,green bandwidth management of access networks and then address the above problems.Recently,extensive research on software defined PON has been started,including three mainly aspects: software defined PON network design,service management and protocol extension.However,there still exist some problems: 1)The bandwidth allocation scheme in PONs is relatively confirmed and can not poll different ONUs with customized scheduling schemes,resuling in user QoE degeneration and inefficient bandwidth management.2)Different operators must deploy their own network infrastructures to serve their subscribers.Bnadwidth resource cannot be effectively shared and then be wasted,resuling in inflexible bandwidth management.3)The active time of an ONU is much longer than its transmission time slot.How to put ONUs into sleep with the guarantee of network delay performance is an interesting issue to save energy and reduce OPEX for opertors.To solve the above problems,the detailed work is as follows:1.Efficient bandwidth management in software defined PONThe bandwidth allocation algorithms of traditional PONs are hard-coded in chip and can not be adjusted according to real-time network situation,resulting in the decrease of user quality of services.To solve it,we introduce the programmable bandwidth scheduling module into PONs and decouple the bandwidth allocation into two dimensions of controller and OLT,which enables efficient PON signaling interaction and real-time algorithm configuration.Then,we design the corresponding bandwidth management strategy in the controller to differentiated ONU scheduling.The experimental results show that the bandwidth management strategy can reduce the network delay,improve the utilization of network resources,and provide efficiency to differentiated ONU services.2.Flexible resource virtualization in software defined PONIn traditional PONs,operators need to build their own network infrastructure to serve their users.However,as the number of users in fixed access networks is relatively fixed,the repeatable PON deployment wastes the PON bandwidth resources and increase the investment risk of operators.To solve this problem,we propose a PON resource virtualization scheme based on the MAC layer.We regard PON MAC frame as a resource slice and introduce a slice scheduler in the controller to assign slices to different operators.We model the problem of resource sharing in the system,and propose corresponding resource sharing schemes.The experimental results show that flexible resource virtualization can guarantee the resource isolation,resource utilization and customizability.3.Green bandwidth scheduling in software defined PONBecause of the large number of ONUs in access networks,ONUs consume a large part of the total PON energy consumption.At the same time,ONUs share bandwidth resources in TDM manner,and the active time of an ONU is much longer than its transmission time slot.To solve the problem,we introduce a MAC control mechanism based on sleep ONU,in which the OLT can put the idle ONUs into sleep to save energy.We model the green bandwidth scheduling problem in the system,and propose the corresponding green bandwidth scheduling algorithms.Experimental results show that the proposed bandwidth scheduling algorithms can minimize the total length of ONU active time with guarantee of network performance.