In current cellular networks, mobility has random characteristics, which makes the channel arrival rate and service application types of cellular networks random, resulting in some cellular networks with excessive channel load and poor resource balance.Therefore, a channel allocation equalization controller for cellular network is designed and implemented based on layered architecture and modularization idea, which includes application layer, control layer and infrastructure layer.The basic module and Application module of the controller work together to realize the balanced allocation of network channel resources. The controller communicates information with the underlying network equipment through the south-facing interface controlled by OpenFlow protocol.Cellular network channel service feeds the resource request command back to the controller through REST interface, which enables the controller to manage the underlying devices to complete the forwarding of resource data and ensure the equalization of channel resource allocation.The experimental results show that the network channel throughput, the average system fairness index, the average outage probability of users and the channel load rate under the designed controller are all excellent, and satisfactory results are obtained.With the development of communication technology, the cellular network with mass data processing performance has high application value in different fields.Cellular network has a large scale, runs more protocols and transmits massive information, which requires high reliability and equalization of network channel [1?3].In current cellular networks, mobility has random characteristics, which makes the channel arrival rate and service application types of cellular networks random. Some cellular networks suffer from excessive channel load and poor resource balance [4?6].Therefore, it is of great significance to find effective methods to improve the equalization of channel resource allocation in cellular networks for enhancing the performance of cellular networks.Literature [7] proposes a cross-layer scheduling and resource allocation scheme to ensure maximum channel throughput and achieve channel allocation equalization control. However, in some channel states, the scheduling rate is higher than mutual information, which will lead to channel packet loss.Document [8] proposes a channel equalization control method based on OpenFlow network.
Under the constraints of channel bandwidth, scalable bit streams can be obtained by distortion optimization method to ensure high stability of signal transmission and reception. However, this method needs to be implemented in a certain bandwidth environment and has some limitations.Document [9] uses time series prediction algorithm to predict channel resource demand, and achieves channel resource equalization control through bandwidth resource reservation algorithm and load balancer. However, it has the drawback of low control efficiency.Literature [10] analyzed the scheme of virtual content service providers, using cloud service providers to lease channel resources dynamically and adjust channel broadband resources according to resource utilization requirements. However, the control cost of this method is high.Based on the layered architecture and modularization idea, this paper designs and implements a channel allocation equalization controller for cellular networks, which includes application layer, control layer and infrastructure layer.The basic module and Application module of the controller work together to realize the balanced allocation of network channel resources.
According to the hierarchical architecture, channel allocation equalization controller is designed including application layer, control layer and infrastructure layer.The controller uses the south-facing interface OpenFlow protocol to control the forwarding behavior of channel resources in cellular networks, and uses the north-facing interface to communicate with the channel resource scheduling platform in the application layer.The overall structure of the channel allocation equalization controller for cellular networks is shown in Figure 1.Infrastructure layer is composed of channel allocation equalization controller switching mechanism. Channel resources are matched, forwarded and controlled according to flow table specifications of controller feedback.Channel allocation equalization controller switch information storage, flow table generation, resource allocation scheme planning and resource download management are all completed by the controller.In the control layer, the key component of the channel allocation equalization controller for cellular network is the controller, which uses the OpenFlow protocol of the south-facing interface to control the data forwarding process of the switch.The control layer provides service and resource calls for users in the upper channel resource scheduling platform through REST northbound interface, and manages the balanced allocation of channel resources in cellular networks.OpenStack Channel Resource Scheduling Platform exists in the application layer. It drives the controller through the northward REST interface, manages the switches in the infrastructure layer, and realizes the comprehensive control of channel resource balanced allocation in the overall cellular network.Controller is the key of channel allocation equalization controller system, which can collect and operate different types of cellular network information.The controller consists of basic module and application module. The two modules work together to achieve the balanced allocation of network channel resources.The basic module is the key of the controller to realize the control of cellular network. It is responsible for the collection of information status of cellular network, the analysis of channel flow, the generation and transmission of channel flow table and so on.The basic module is composed of flow table generation, information storage, channel resource allocation planning and other modules.When the application module starts the controller, it starts the corresponding application modules such as channel resource load balancing and resource allocation balancing according to different requirements. The Application module calls the functions and information related to the basic module to complete the channel resource balancing allocation function. At the same time, it provides resources and interfaces to the application layer to support the channel resource balancing of cellular network. Dispatch business processing.The controller is the control center of the channel allocation equalization controller system.
Its working logic determines the function and performance of the controller, and plays an important role in the operation of the overall cellular network system.According to the working principle of OpenFlow protocol, the working logic between the controller modules is designed, as shown in Figure 2.After the switch is connected with the controller, it registers with the device management module of cellular network. The device management module stores the information of the switch in the information storage module, and shapes two threads of acquisition and transmission to complete the operation of the switch data.After the controller collects the data packet from the switch feedback by the thread, the data packet is input into the queuing operation.The acquisition thread retrieves the data packet in the queue and feeds the data packet back to the data distribution module.Data Distribution Module parses data packages and feeds them back to Device Management Module for operation if their contents are device information; If management information is used, the data packages are fed back to Channel Resource Equilibrium Allocation Scheme Planning Module for operation; If network data is used, the data packages are fed back to Link Discovery Module to stimulate the module. Function.After the link discovery module collects the data packet, it runs the link discovery process, feeds the data packet back to the channel resource downward management module, thermostatic element and the channel resource downward management module encapsulates the data packet into information, at the same time feeds back the information to the switch.Each time the link discovery process is completed, the link discovery module stores the link information in the information storage module, and transmits the link information to the network topology module for operation.The network topology module shapes the cellular network topology according to the received link information, calculates the channel resource allocation path, and stores the channel resource allocation path information in the information storage module to provide analysis basis for other modules.The resource allocation scheme planning module comprehensively analyses the information and control information of cellular network, obtains the channel resource allocation scheme of cellular network, and transmits the channel resource allocation scheme to the flow table generation module to obtain the related static and dynamic flow tables.The download management module encapsulates the flow table and the information sent to the switch, and feeds the encapsulated data packet back to the transfer thread of the switch for queuing.The coordinated operation of each module of the controller ensures that the channel resources of the cellular network are equally allocated by the controller to ensure the smooth operation of the network.The controller is connected with the basic facility layer, the application plane layer and the control plane layer through the interface system.The interface system of the controller consists of the South-to-North interface and the north-to-north interface.
The controller communicates the resource scheduling information with the underlying network facilities through the south-facing interface controlled by OpenFlow protocol; the cellular network channel service feeds the resource application command back to the controller through the north-facing REST interface, which enables the controller to manage the underlying equipment to complete the forwarding of resource data and realize the balanced allocation of channel resources.OpenFlow protocol involves the south-facing interface to realize the exchange of information between the controller and the underlying switch.The data package is transmitted to the controller through the southward interface for operation. According to the underlying network topology and the switch situation, the controller calculates the network channel operation flow and flow chart, and feeds back the operation results to the switch through the southward interface.The switch analyzes and stores the flow table information fed back by the controller according to the openflow protocol. When new data appears, the switch compares it with the stored flow table to enhance the efficiency of data forwarding and network channel resource allocation.The OpenFlow protocol stipulates that the controller communicates with the switch through TCP with a port of 6633, and sets up the message type structure for the communication between the switch and the controller. The message type includes HELLO, ECHO and VENDOR messages used for the connection between the switch and the controller. The controller inquires about the information of the switch and FEATURES for the transmission of management information. It also describes the control information of other controllers to the switch.These types of information realize the interaction between the controller and the switch, and ensure the accuracy of the channel resource balanced allocation control of the overall cellular network.The upper service application drives the controller to schedule the channel resources of cellular network through the northward interface of the controller, and realizes the equalization of the channel resources of the network to the upper application.The northbound interface of the controller is designed with REST API scheme, which has strong relevance and addressability.The controller communicates with OpenStack, the channel resource allocation platform of the upper fusion cellular network based on REST. The management platform achieves the balanced control of channel resources through the arrangement and scheduling of the underlying network resources by the controller.The integrated architecture of the controller and the channel resource allocation platform of cellular network is shown in Figure 3.In order to verify the performance of the controller designed in this paper, relevant experimental analysis is carried out.The channel resource utilization of a multi-user and single-cell cellular network is analyzed in the experiment.The performance of the controller, the multi-channel scheduling method and the cross-layer scheduling method are analyzed from four indicators: network channel throughput, average system fairness index, average user interrupt probability and channel load rate.Analysis of Figure 4 shows that with the improvement of the signal quality of cellular network, that is, the increase of average SNR, the channel throughput of the three control methods is increasing, and the channel throughput of the control method in this paper is significantly higher than that of the other two control methods.The fairness index is used to evaluate the fairness of the channel under the two methods, and then the average throughput of different cellular network users is analyzed.As shown in Figure 5.Formula: JE is a fairness index; [rk] represents the rate of the k th user; K represents the current user; and K represents the total number of users.Analysis of Fig. 5 shows that the average system fairness of channel resource equalization control under this controller is the highest compared with the other two control methods. The main reason why this method achieves the highest average system fairness is that according to the hierarchical architecture and modularization idea, through the collaboration of application layer, control layer and infrastructure layer, this method can achieve the highest average system fairness. Running to achieve a balanced allocation of network channel resources, to ensure the long-term fairness of network channel resources between users.The average channel interrupt probability under the three control methods is shown in Fig. 6.Analysis of Figure 6 shows that when the average signal quality SNR of the channel is lower than 17 dB, the average channel interrupt probability of the proposed control method is slightly higher than that of the other two methods. When the average signal quality SNR of the channel is higher than 17 dB, the average channel interrupt probability of the proposed control method is much lower than that of the other two methods with the increase of the average signal quality of the channel. The average outage probability of the channel in the cross-layer scheduling method increases rapidly, and the average outage probability of the proposed method remains at a relatively low level.The main reason is that the control method in this paper can ensure that the user resource scheduling process is in a stable state, so that the overall channel has a lower average interrupt probability.However, the cross layer scheduling method does not set the maximum rate constraint for users. If users are in the environment with more resources, they have a higher data rate, which makes the channel average outage probability rapidly increased.The lower the channel load rate, the higher the time consumed in network channel control, and the longer the network tends to be stable.Therefore, the experiment compares and analyses the channel load rate under the control method and cross-layer scheduling method as shown in Figure 7.As can be seen from Figure 7, the channel load rate of the proposed method is lower than that of the cross-layer scheduling method, and with the increase of the number of nodes, the gap between the two methods increases gradually.It shows that the control method in this paper has high adaptability and robustness.Based on the layered architecture and modularization idea, this paper designs and implements a channel allocation equalization controller for cellular networks, which includes application layer, control layer and infrastructure layer.The basic module and Application module of the controller work together to realize the balanced allocation of network channel resources.The controller communicates information with the underlying network equipment through the south-facing interface under the control of OpenFlow protocol; the cellular network channel service feeds the resource application command back to the controller through REST interface, which enables the controller to manage the underlying equipment to complete the forwarding of resource data and ensure the equalization of channel resource allocation.The experimental results show that the network channel throughput, the average system fairness index, the average outage probability of users and the channel load rate under the designed controller are all excellent, and the satisfactory results are obtained.