Research On BLE Neighbor Node Discovery Technology Based On Circle

With the rapid development of the Internet of Things technology,BLE(Bluetooth Low Energy)technology is becoming increasingly mature.Compared with the traditional classic Bluetooth,BLE has many advantages such as faster transmission rate,lower cost and lower energy consumption,making BLE technology widely used in the fields of smart home,flood and earthquake resistance,and medical protection.However,these applications are inseparable from the important premise of BLE neighbor node discovery.Although BLE technology alliance has defined a new set of neighbor node discovery protocol,there are some problems in the process of neighbor node discovery.When the pseudo-random broadcast delay does not exist,improper selection of working parameters will lead to continuous conflict between nodes and failure to complete discovery.When the pseudorandom broadcast delay exists,the discovery delay between BLE nodes is very sensitive to the working parameters,and there is no good theoretical model to accurately quantify the discovery delay.Aiming at the above two problems,we give the following work:Firstly,we analyze the situation that the pseudo-random broadcast delay does not exist.Based on the Circle model and BLE Circle model,we first analyze the properties of BLE neighbor node discovery under single channel,including the necessary and sufficient conditions of mutual discovery between BLE neighbors,the lower bound of discovery delay between nodes and how to obtain the lower bound,and how to solve the BLE Circle model when obtaining the lower bound of discovery delay.Secondly,the sufficient and necessary conditions of mutual discovery between BLE nodes under three channels are analyzed,and the calculation method of discovery delay between BLE nodes is given.Then,considering the existence of pseudo-random broadcast delay,we present how to use Jacobian iterative method to calculate the expected discovery delay between BLE nodes based on BLE Markov neighbor node discovery model.On the basis of this theory,the conditions for working parameters of nodes to avoid using these parameters are studied when the expected discovery delay between nodes reaches a maximum.Finally,a BLE neighbor discovery delay simulation scheme and a neighbor discovery delay experiment based on NRF 52832 node are designed to verify the accuracy of BLE Markov neighbor discovery model from two aspects: the expected discovery delay of nodes and the expected discovery delay of specified initial phase difference.The parameters obtained from the theory of expected discovery delay maximum value analysis are used to simulate the BLE neighbor node discovery delay,and the simulation results agree well with the theoretical analysis.