Research On Parameter Optimization Method Of Neighbor Discovery Based On BLE-Circle

In the discovery protocols based on Bluetooth Low Energy(BLE),most protocols only give the corresponding maximum discovery delay or average discovery delay after setting the working parameters according to the protocol.However,different working parameters can sometimes be obtained.The same discovery delay but the corresponding duty cycle is quite different.In the actual wireless sensor network design,it is found that the delay often needs to meet the scene requirements,and a lower duty cycle can increase the working time of the node.Therefore,under the condition of satisfying the discovery delay,how to choose a set of optimal working parameters,so that it can not only meet the discovery delay requirements of wireless sensor networks,but also minimize the duty cycle becomes a problem that needs to be considered in the design of the network.In response to the above problems,this paper proposes a parameter optimization method based on the Circle model and the BLE-Circle model.By analyzing the relationship between the parameters,a mathematical model is established to obtain the minimum duty cycle under different discovery delay requirements and the corresponding working parameters.At the same time,the conflict between nodes in the multi-node scenario is analyzed,and the optimal working parameters are selected for the multi-node scenario using the parameter optimization method,which can make the duty cycle meet the requirements of discovery delay.The specific work is as follows:First of all,this paper briefly introduces the Circle discovery model and the BLE-Circle model,and analyzes the common problems of the two models,that is,both models only analyze the discovery delays corresponding to different working parameters,and do not analyze the minimum proportion of the same discovery delay.Aiming at this problem,this paper proposes a parameter optimization method,which solves the problem of how to select the working parameters of the two models under different discovery delay requirements.The parameter optimization method achieves the purpose of minimizing the duty cycle while meeting the discovery delay requirements.By analyzing the parameter relationship of the Circle model when the maximum discovery delay is obtained,the optimal working parameters are solved,which not only meets the discovery delay requirement,but also has the lowest duty cycle.On this basis,the parameter relationship between the maximum discovery delay and the expected discovery delay of the BLE-Circle model is analyzed,and the optimal working parameters are obtained to make the duty cycle the lowest.Finally,the correctness of the method is verified by simulation and experiments on Nordic nrf52832 node.Then,this paper analyzes the impact on the BLE discovery process when there are multiple neighbor nodes.On this basis,for two different application scenarios,the parameter optimization method proposed in this paper is used to select parameters according to different discovery delay and discovery probability requirements in the scenarios.The results show that the optimal working parameters selected by the parameter optimization method can still meet the requirements of the scene,and at the same time make the duty cycle the lowest.Its correctness is verified by simulation and experiments.Then,the problem of continuous conflict between multiple neighbor nodes is further analyzed.It is proved that when multiple neighbor nodes have the same working parameters,once a conflict occurs,the discovery probability between nodes will be greatly reduced,and may even never be discovered.In response to this problem,this paper proposes a method based on the BLECircle model to reduce the impact of continuous conflict on the discovery of neighbor nodes.This method reduces the number of collisions and improve the discovery performance of the protocol under the condition of the same duty cycle.And the correctness of the method is proved by simulation and experiment.