From the above figure , we can see the original structure remains unchanged and the new packet - switched network is formed by adding a packet control unit ( pcu ) to the bss part 圖1gprs網(wǎng)絡(luò)結(jié)構(gòu)從網(wǎng)絡(luò)結(jié)構(gòu)圖可以看到,原有的網(wǎng)絡(luò)結(jié)構(gòu)保持不變,只是在bss部分增加了分組控制單元( pcu ) ,新建了一個分組網(wǎng)絡(luò)。