LTE/LTE-A System Performance's Optimization And Design Based TTI's Adjustment

The 3rd Generation Partnership Project opened a Long Term Evolution project 10 years ago.This program uses a variety of new technologies,by introducing a new resource scheduling to assign the radio resources to individual users,to fully enhance data transmission efficiency,reduce system latency and improve the cell capacity.LTE-Advanced is an evolution of LTE,which is equally committed to the contents of a number of key technical indicators,such as higher peak rates,the greater system bandwidth,higher system capacity,smaller user plane and control plane delay,etc.Also has been widely supported internationally.With the rapid development of wireless communication technology,the number of mobile users is also rapidly expanding,and the system needs to support more diverse type of business,so people's requirements on the data transmission rate also have a lot of growth.Since spectrum resources which in the network is limited,how to use the limited resources efficiently has become a hot topic.This article focus on the TTI's(Transmission Time Interval)adjustment,change the frame structure of LTE/LTE-A system and study the optimization.First,this article introduces the LTE/LTE-A system,including system features,system architecture,several key technologies.According to the architecture and related protocols,using C++ programming software to simulate this system.Secondly,according to the current trends,the system's capacity has higher requirements,so we proposed Shorter TTI system solutions.TTI is reduced by half,which uses a 0.5ms TTI scene,by modifying the timing relationship platform,which 0.5ms called once,improving the efficiency of data transmission based on TCP protocol operations.It improves the growth rate of TCP window,while the other business based on UDP protocol like VoIP,also have a certain degree of optimization.Due to the length of TTI halved,Transport Block Size's calculation takes into account the issue of halving,increasing the effective load ratio.From the simulation results,under ideal conditions,delay,throughput,system capacity and other aspects of FTP,HTTP,VoIP and other services have had a certain amount of gain.Then,based on the Shorter TTI systems and Normal TTI systems'analysis,we proposed the concept of mixed TTI systems.The advantages of the new type systems were combined with these two programs,taking into account the resource cost advantages in Shorter TTI system and power overhead advantages in Normal TTI system.So,high reliability,wide coverage,low latency,high throughput characteristics were combined in one system.In the end,we use simulation to prove the feasibility of this program,and get satisfactory theoretical results.