GSM-R has been in a fast development period in China and it will play a more and more important role in the construction and operation of China railway. There is only four mega-hertz spectrum in GSM-R with many applications,for example,the railway emergent call,the train schedule,the train control,passenger information service and so on.Different application demands different quality of service.These different services demand different resources.Therefore,GSM-R system is a severe resource restricted system.Marshaling yard plays an important role in railway transportation organization.The traffic in marshaling yard is large and the topography environment complex.If radio resources in marshaling yard can be used efficiently,it will play a promoting role in the construction of GSM-R network.The voice and data simultaneous transmission mode has been researched. According to application demands in marshaling yard,the VGCS signaling flow has been modified and complemented in order to realize voice and data simultaneous transmission function in all kinds of VGCS situations which has promoted the development in this kind of GSM-R technology area.Through research on packet data service resource mode and the basic network structure、protocol hierarchy mode、GSMS entity,the transmission procedure and signaling flow of short message transmission during an ongoing voice group call in the circuit switched domain has been improved in order to propose the transmission procedure and signaling flow of the short message transmission during an ongoing voice group call in GPRS network.
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