原创 无线通信链路预算的可用度分析

无线链路预算是一种定量评估通信链路是否会成功执行的计算。它提供了对功率预算的详细分析，说明了传输路径每个阶段的增益和损耗。包含天线架高计算，菲涅尔区半径计算，天线口径计算，自由空间损耗，接收信号电平计算，链路余量，可用度计算等等；

比如在南京地区部署X波段高速通信系统，通信距离10公里，全双工速率2Gbps：

link budget 步骤如下：

1. 查阅气象资料得知：南京地区降雨63mm/h，年平均气温15℃，

2. 查阅通信站点的经纬度坐标，对天线架设高度高进行计算；

3. 菲涅尔半径计算，确保第一菲涅尔区60%可用；

4. 计算接收门限Threshold= -114+10log(BW)+NF+Eb/No

5. 确定链路余量fade margin, 计算链路接收电平；

6. 计算链路的系统增益；

7. 计算自由空间链路损耗Free space path loss =92.4+20log(freq)+20log(distance)

8. 计算天线增益，确定天线口径尺寸；

9. 根据统计信息，计算链路的可用度，比如上述链路通过计算得知：综合考虑多径传输和降雨影响Multipath + Rain Availability，其中垂直极化可用度99.995%，水平极化可用度99.992% 

验证：上述数据和参数输入MATLAB链路预算工具，仿真计算后得到的结果基本与上述计算结果一致。

Ref.

Importance of Link Budgets

Link budgets are essential for several reasons:

1.     System Design: Link budgets guide the design and dimensioning of communication systems, ensuring that the transmitted power, antenna gains, and receiver sensitivity are appropriately chosen for reliable communication.

2.     Performance Evaluation: By accounting for all gains and losses, link budgets provide a quantitative assessment of the system’s performance, helping engineers estimate the achievable data rates, coverage range, and signal quality.

3.     Regulatory Compliance: Link budgets help ensure compliance with regulatory standards, such as maximum permissible transmit power levels, interference limits, and signal quality requirements.