一、概述 当前，专用移动通信系统正在向集群化方向发展，国内对专用网的需求日益迫切。就集群系统本身而言，又分为模拟信令和数字信令，其中数字信令代表了专用移动通信系统的发展趋势，较模拟信令有许多优点，因此，数字信令专用通信系统发展更为迅速。现有的公安集群移动通 I. Overview At present, the private mobile communication system is moving towards the direction of clustering. The domestic demand for private networks is increasingly pressing. Cluster system itself, is divided into analog signaling and digital signaling, of which digital signaling represents the development trend of private mobile communication system, compared with analog signaling has many advantages, therefore, the development of digital signaling communication system For speed. The existing public security cluster mobile communications