Research And Implementation Of Packet Data Convergence Protocol In 5G System Based On Super Base Stations

The super base station is a new centralized cellular network architecture based on global resource sharing.It is characterized by implementing modular software and hardware,controling centrally protocol resources and designing customly protocol software.In order to meet the requirements of platform-based super base station communication software and supporting multi-mode heterogeneity,a new design of the entire protocol stack software architecture is required.In the 5G protocol stack,the Packet Data Convergence Protocol(PDCP)not only needs to solve the data offload problem of the 5G dual connectivity technology,but also is responsible for the data transmission between the user plane and the control plane.Functions of PDCP include header compression and decompression,encryption and decryption,integrity protection and verification,and so on.To ensure the security of the data,PDCP is essential to the entire protocol stack.This thesis researches and implements the PDCP layer under the super base station 5G protocol stack software architecture.The main contributions of this thesis are as follows:1.Firstly,this thesis investigates and analyzes the shortcomings of existing offloading algorithms.Then,combining with the requirements that the actual system algorithm can not be too complex,this thesis proposes an improved offloading strategy.The strategy not only determines the proportion of allocated packets,but also the order in which the packets are transmitted,so that the data packets can arrive at the receiving point in order,which can reduce the reordering time and improve the system throughput.Lastly,this thesis compares the throughput and reordering packet loss rate of the offloading strategy with OMS algorithm and optimal split ratio algorithm.The results show that in the case of the throughput of the two links is 20Mbit/s and 80Mbit/s respectively,and the packet loss rate is 1% and 2% respectively,compared with the OMS algorithm and the optimal offloading ratio algorithm,the throughput of the improved offloading strategy is improved by 32Mbit/s and 58Mbit/s respectively and the reordering packet loss rate is reduced by about 25% and 60% respectively.2.Based on the research and analysis of the existing PDCP layer protocol software design,combined with the requirements that the super base station system should support the multi-mode heterogeneous,a component-based design scheme is proposed.The scheme divides the entire PDCP layer into functional modules and functional components by function granularity,and unifies the external link interface and functional component interface.And combined with the dynamic link library form and bus-type communication mode,functional component can be combined according to the network requirements,so as to achieve the effect of flexible switching between different standard protocol functions and processing flow.3.First,the functional modules such as 5G PDCP layer entity management,header compression and decompression,encryption and decryption,integrity protection and verification,and protocol processing flow are implemented according to the component-based design scheme.Then,this thesis builds a test environment to verify the correctness and completeness of its functions and processes.The test result proves that the modular design asides from meetting requirements of system functions and performance,also possesses flexibility.