Guangzhou 800 MHz Digital Trunking PAMR (Public Access Mobile Radio) from the basic communication platform of Guangzhou authorities is to enhance her municipal management abilities and emergency response abilities. Signal coverage for metro network is one of the targets of the digital trunking PAMR, as on one hand to strength abilities on underground emergency handling and security command and control, and the other hand to enhance digital trunking PARMR's influence. This paper discusses the present situation on digital trunking PAMR, and analyses its network dimensions and application, and further discusses expansion, disposal of the network system and the indoor coverage technique at underground and metro areas. <<