# Collaborative Channel Perception of UAV Data Link Network Based on Data Fusion
## 2 Collaborative Channel Perception Algorithm
### Analysis of Characteristic Parameters of Node Devices  
The channel traffic pulse statistical capability of node devices is closely related to their transmission and reception performance. The counting capability of received and transmitted pulses, the degree of component aging, and operational reliability all have significant impacts on node device performance. Among these, the critical parameters affecting the counting performance of received pulses for node devices are the receiving sensitivity and the signal-to-noise ratio (SNR). For the counting performance of transmitted pulses, the voltage standing wave ratio (VSWR) of the antenna is an important parameter. The number of operating months reflects the extent of aging of node devices, while the mean time between failures (MTBF) is an essential indicator of operational reliability. This paper evaluates the transmission and reception performance of node devices by monitoring their characteristic parameters in real time, including the receiving sensitivity, the VSWR of the antenna, the SNR, the number of operating months, and the MTBF. The receiving sensitivity is a typical scalar parameter that indicates the lowest signal amplitude that a node device can normally receive and process a data link signal. This directly affects its capability to accurately count the number of received pulses. Antenna VSWR, serving as a negative indicator, reflects the extent of radio frequency (RF) energy reflection in a node device. This directly impacts the radiation performance of the data link signal by causing a reduction in its transmission distance. When there is an impedance mismatch between the node transmitter and the antenna system, it can result in some RF energy of the data link signal being reflected, creating a reverse echo signal. This, in turn, leads to a reduction in the transmission distance of the data link signal. Additionally, SNR, another scalar parameter, indicates the quality of the electromagnetic environment and significantly impacts the capability of node devices to accurately count the number of received pulses. The number of operating months is a reflection of the aging degree of the components in node devices. With an increase in operating months, the component aging intensifies, inevitably affecting both transmission and reception performance and diminishing their statistical capability to process traffic pulses. MTBF describes the ratio of failure time to operating time in the current environment, serving as a crucial metric for assessing operational reliability. This parameter significantly impacts the credibility of traffic pulse statistical results for node devices. Multiple factors influence the traffic pulse statistical capability of node devices, reflecting different aspects of their physical performance. However, the amplitude or dimension of these factors varies significantly. To reasonably evaluate the traffic pulse statistical capability of node devices, a normalized dimensionless method can be employed to process different types of influencing factors. By comparing the receiving sensitivity \(\sigma_{i}^{t}\) at time \(t\) with the maximum tolerance value and the nominal value, it is converted into a normalized value ranging from 0 to 1. The normalization formula for the receiving sensitivity \(\xi_{i}\) of node \(i\) is expressed as:  
\[\xi_{i}= \begin{cases}1&\sigma_{i}^{t}\leq\sigma_{i}^{u}\\ \frac{\sigma_{i}^{max}-\sigma_{i}^{t}}{\sigma_{i}^{max}-\sigma_{i}^{t}}& \sigma_{i}^{u}\leq\sigma_{i}^{t}\leq\sigma_{i}^{max}\\ 0&\sigma_{i}^{t}\geq\sigma_{i}^{max}\end{cases}  \tag{1}\]  
where \(\sigma_{i}^{max}\) represents the maximum tolerance value of the receiving sensitivity of the node device, \(\sigma_{i}^{t}\) represents the detected value of the receiving sensitivity at time \(t\), and \(\sigma_{i}^{u}\) is the nominal value of the receiving sensitivity.