Research On Some Key Issues Of Asynchronous Network-on-Chip Based On Reconfigurable Technology

With the development of embedded system for intelligent information processing and the progress of semiconductor technology,more and more processors and IP cores can be integrated in System on Chip(SoC).The complexity of bus structure grows exponentially with the increase of processors and IP cores in SoC,and with the complex communication between multi-cores,the bus communication structure gradually becomes the performance bottleneck of speed,power,area,and the data throughput of SoC.By using computer network technology,Network-on-Chip(NoC)provides a flexible,efficient and reliable solution for the communication of processors and IP cores.Routing and packet switching is used in NoC for the communication.NoC could be implemented in synchronous or asynchronous ways.But with the complication of the embedded applications,especially with the coming of the big data era and the increase in the needs of intelligent information processing systems,more and more types of IP cores are mounted on the NoC,which work normally in different frequencies.Therefore,the study of asynchronous NoC becomes extremely important.In order to improve the performance of asynchronous NoC in average network delay,network throughput rate,topology utilization,power consumption,data transfer rate,and etc,this paper carries deep research on some key issues,that is,routing algorithm,power consumption optimization algorithm,topology structure and communication mechanism based on reconfigurable technology.The main research results are as follows:(1)A DA-XY adaptive routing algorithm based on dynamic congestion feedback mechanism is proposed in the aspect of NoC routing algorithm.In order to solve the problem of low rate of topology utilization and local blocking of the NoC during data packet routing process,a DA-XY adaptive routing algorithm based on dynamic congestion feedback mechanisms in 2D-Torus topology is proposed.The'search-feedback' mechanism is used,and a local congestion signal is added in the routing node.The blocking information in the cache of surrounding routing nodes is monitored in real time,and the shortest routing path strategy is used to adjust the routing path dynamically,in order to avoid the blocking area and to reduce the routing delay.Theoretical analysis and simulation results show that this algorithm has high data throughput,low average transmission delay and strong adaptivity.Based on reconfigurable technology,an asynchronous 2D-Torus NoC is designed.The test results show that there is diversity of the shortest routing path in DA-XY algorithm.And the load of single routing link is reduced,while congestion could be avoided.And when the NoC is congested locally,the data packet could effectively bypass the congested or failure routing nodes,therefore the performance of NoC is improved.(2)In terms of energy consumption optimization and management,a reliable voltage frequency island(VFI)energy optimization algorithm for asynchronous NoC RaVFIMAP is proposed.In the context of video processing,and based on the design concept of VFI,the method adopts a progressive optimization approach.VFI partitioning,assignment and task mapping is implemented.During energy optimization,a reliability model for 2D-Torus topology and DA-XY routing algorithm is proposed,and the corresponding reliability energy overhead is defined.By considering this energy overhead during task mapping process,the reliability of asynchronous NoC can be improved.By the simulation of random tasks and video processing application examples,the results show that RaVFIMAP algorithm could improve the reliability of the system to a great extent.And compared with the other energy optimization algorithm,the energy consumed by RaVFIMAP still has certain advantages.(3)A H-annular Mesh topology based on semi-circular link is proposed in terms of NoC topology.In NoC system,the interaction frequency between master nodes and ordinary routing nodes is much higher than that between ordinary routing nodes.To solve this problem,a H-annular Mesh topology is proposed.Half ring connections between several main routing nodes and common routing nodes are added to shorten the routing path length between the column and head main nodes and the center nodes.Therefore,the average routing path could be reduced for the entire NoC.HAA-XY routing algorithm is proposed for H-annular Mesh topology.The routing nodes are divided into three categories and a classified routing strategy is used.At the same time,by search-feedback adaptive routing strategy,the robustness of the NoC is improved.Based on reconfigurable technology,a 6 X 6 NoC using H-annular Mesh topology and HAA-XY routing algorithm is designed and implemented in the FPGA platform.The test results show that the H-annular Mesh topology improves the data interaction between master routing nodes and ordinary routing nodes,and has a smaller routing delay.(4)A dual-mode-fusion communication mechanism is proposed.In GALS NoC,based on the problem of traditional communication mechanism,and considering the VFI design concept,a dual-mode-fusion communication mechanism is proposed.According to the characteristics of the transmitted data in NoC,the data is divided into control message and data message.And the data transmission is carried out by different communication mechanisms.At the same time,a configurable dual-mode-fusion data communication interface circuit is proposed.Therefore,the commonality of the routing nodes is increased,and the problems of current asynchronous FIFO with depth and single data transmission channel are solved.Based on reconfigurable technology,the NoC based on the dual-mode-fusion communication mechanism is designed and realized in the FPGA platform.And the video processing algorithm is used as an example to construct the video processing system.The test results show that the NoC with dual-mode-fusion communication mechanism has a smaller transmission delay,greater throughput,and better video processing performance for video procesing applications.