7KALDEN R,MEIRICK I,MEYER M. Wireless internet access based on GPRS[G]. Atlanta,USA:IEEE Press , 2000 :134-136.
8European Telecommunications Standards Institute(ETSI). GSM04. 06,Mobile Station- Base Station System (MS- BSS) interface Data Link (DL) layer specification version 6.0.0 [S]. [S.l.] :ETSI, 1997.
9European Telecommunications Standards Institute(ETSI). GSM04. 10,Mobile radio interface layer3 supplementary services specification general aspects version 6.0.1 [S]. [ S.l. ] : ETSI, 1997.
10European Telecommunications Standards Institute(ETSI). GSM 07. 05,Digital cellular telecommunications system (Phase 2+ ). Use of Date Terminal Equipment-Data Circuit terminating~Equipment (DTE-DCE) interface for Short Message Service (SMS) and Cell Broadcast Service(CBS) (GSM 07.05 version 5.5.0) [S]. [S.l.]: ETSI, 1998.