Study On The Technology Of Event Aggregation And Speedup For WLAN Simulation By NS-3

Discrete Event Simulation is widely used in the field of communication network.When simulating large-scale network or overloaded behavior,both the total number of events and total calculation time show an exponential growth trend.Therefore,it is urgent to explore discrete event simulation acceleration technology.Though parallel and distributed simulation can expand the scope of network and reduce simulation time,the performance improvement of parallel and distributed simulation needs a lot of computing resource and money.This thesis aims at expanding NS-3 platform,and exploring event aggregation method to compress and reduce redundant simulation event,improving simulation speed.Firstly,this thesis discussed Physical Layer,Media Access Control Layer,Channel Access Manager and other object classes related to wireless simulation in NS-3,analyses sending and receiving process of packets.Based on the correlation of received events and channel interference,the computational redundancy of concurrent event simulation is obtained.On this basis,a program breakthough of simulation event aggregation is designed,the cache and batch processing scheme of concurrent packets are proposed.Secondly,a batch processing flow of received packets is proposed.The calculation function of the channel object class is extended,the caching,sorting and aggregation of concurrent packets are achieved.By expanding the physical object class and new batch processing method,the multiple determined packet conflicts are combined to reduce the number of repeated channel state updates.Finally,a Wi Fi simulation scenario with a maximum number of stations of 1000 is designed.Simulation experiments are carried out to verify the correctness and acceleration performance of the event aggregation scheme.The result shows that event aggregation scheme can compress redundancy of channel interference simulation,the simulation acceleration factor is positively correlated with the network scale.When the number of wireless stations is 1000,the acceleration factor can reach 7.5.Under the comprehensive simulation condition of mixed backoff process,the maximum acceleration ratio can reach 1.3.