| 摘要 |
An apparatus for transmitting TDM(Time Division Multiplexing) frames using a packet network in a mobile communication system is provided to offer a circuit switched service at a small outlay by utilizing a packet network as a transmission line for the purpose of removing circuit rents, without adding auxiliary equipments to the packet network. An apparatus for transmitting TDM frames using a packet network in a mobile communication system comprises a TDM access interface(10), a payload assembly(11), a protocol engine(20), a packet transmitter(13), a host interface(16), a packet receiver(19) and a TDM formater(21). The TDM access interface(10) has many input/output data circuits which have their respective DCOs(Digital Clock Oscillators), and executes clock recovery at each of the output circuits. The payload assembly(11) configures a packet payload through sampling for the data received through the TDM access interface(10), records a completed payload in a memory, and transmits a task message to a central task manager(12). The protocol engine(20) adds an upper layer protocol header to a packet processed through the payload assembly(11), and divides the header into a static field and a variable field. The packet transmitter(13) adds a lower layer protocol header to a packet which is ready for transmission. The host interface(16), which is used in case information about control data and network setup is required, supports dual address DMA(Direct Memory Access) between a chip and a CPU. The packet receiver(19) receives packets, determines the destinations of the received packets, and classifies the received packets according to contexts equivalent to the destinations. The TDM formater(21) restores the received data to TDM data, arranges the received packets in order, appoints each octet to a time slot selected in the TDM access interface(10), and adds 'UnderRun' data when a packet loss or delay is generated.
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