This paper proposes a link budgeting approach to address the quality of service (QOS) for wireless communication links. The measures for the QOS include the coverage radius, line-of-sight occurring rate, and confidence level. The QOS-based link budget analysis can significantly reduce transmission powers in situations where more line-of-sight paths exist and lower confidence level is allowed. In comparison to traditional link budgeting methods, the QOS-based budgeting method can lead to significant energy saving.