fig1 shows the core network interface architecture of the asynchronous mobile communication system . as shown in fig1 , an asynchronous mobile communication system to which the present invention is applied includes an asynchronous mobile station 100 , an asynchronous radio network 200 and an asynchronous core network 300 . particularly , in order to employ hybrid arq types ii and iii technique more efficiently , the present invention is embodied for data retransmission between the asynchronous mobile station 100 and the asynchronous radio network 200 . in more detail , when the asynchronous radio network 200 transmits data to the asynchronous mobile station 100 , a transport format combination indicator ( tfci ) is included in the data . the tfci includes information of whether data received at the asynchronous mobile station 100 are retransmitted data or not . also , an upper layer or a physical layer can analyze the tfci without getting a support for the analysis from the other layers . conversely , the asynchronous mobile station 100 transmits to the asynchronous radio network 200 data including the tfci by which the asynchronous radio network 200 is informed of retransmitted data or not . fig2 a shows a configuration of an asynchronous radio network to which the present invention is applied . as shown in fig2 a , when a radio frequency ( rf ) unit 210 receives radio data from an asynchronous mobile station , the rf unit 210 transmits the radio data to a buffer 221 of a layer 1 220 . also , when receiving modulated data from a modulation unit 223 of the layer 1 220 , the rf unit 210 converts a modulated data format to a radio data format and then transmits the converted data to the asynchronous mobile station . radio data that are transmitted via the rf unit 210 from the asynchronous mobile station are stored in the buffer 221 of the layer 1 220 and , according to a direction of l 1 control unit 224 , the buffer 221 supplies the radio data to a demodulation unit 222 of the layer 1 220 . under control of the l 1 control unit 224 , the demodulation unit 222 demodulates the radio data supplied from the buffer 221 and then transmits the demodulated data to a data reception / analysis unit 231 of an upper layer 230 . the modulation unit 223 modulates data from a buffer 233 of the upper layer 230 according to instructions of the l 1 control unit 224 and then transmits the modulated data to the asynchronous mobile station via the rf unit 210 . as seen from described above , the l 1 control unit 224 controls the buffer 221 , the demodulation unit 222 and the modulation unit 223 that are included in the layer 1 220 . the data reception / analysis unit 231 of the upper layer 230 receives and analyzes the demodulated data from the demodulation unit 222 according to a direction of an upper layer control unit 234 and then transmits the data to an asynchronous gsm - map core network 300 . a data generation unit 232 of the upper layer 230 supplies data from the asynchronous core network 300 to the buffer 233 of the upper layer 230 under control of the upper layer control unit 234 and the buffer 233 supplies the data stored therein to the modulation unit 223 of the layer 1 220 according to a direction of the upper layer control unit 234 . the upper layer control unit 234 controls the data reception / analysis unit 231 , the data generation unit 232 and the buffer 233 that are included in the upper layer 230 . fig2 b shows a configuration of an asynchronous mobile station to which the present invention is applied . as shown in fig2 b , when a radio frequency ( rf ) unit 210 receives radio data from an asynchronous radio network , the rf unit 210 transmits the radio data to a buffer 121 of a layer 1 120 . also , when receiving modulated data from a modulation unit 123 of the layer 1 120 , the rf unit 210 converts a modulated data format to a radio data format and then transmits the converted data to the asynchronous radio network . radio data that are transmitted via the rf unit 210 from the asynchronous radio network are stored in the buffer 121 of the layer 1 120 and , according to a direction of l 1 control unit 124 , the buffer 121 supplies the radio data to a demodulation unit 122 of the layer 1 120 . under control of the l 1 control unit 124 , the demodulation unit 122 demodulates the radio data supplied from the buffer 121 and then transmits the demodulated data to a data reception / analysis unit 131 of an upper layer 130 . the modulation unit 123 modulates data from a buffer 133 of the upper layer 130 according to instructions of the l 1 control unit 124 and then transmits the modulated data to the asynchronous radio network via the rf unit 110 . as seen from the above description , the l 1 control unit 124 controls the buffer 121 , the demodulation unit 122 and the modulation unit 123 that are included in the layer 1 120 . the data reception / analysis unit 131 of the upper layer 130 receives and analyzes the demodulated data from the demodulation unit 122 according to a direction of an upper layer control unit 134 and then transmits the data to an application part 400 . a data generation unit 132 of the upper layer 130 supplies data from the application part 400 to the buffer 133 of the upper layer 130 under control of the upper layer control unit 134 and the buffer 133 supplies the data stored therein to the modulation unit 123 of the layer 1 120 according to a direction of the upper layer control unit 134 . the upper layer control unit 134 controls the data reception / analysis unit 131 , the data generation unit 132 and the buffer 133 that are included in the upper layer 130 . as shown in fig2 a and fig2 b , in case a data reception side of the asynchronous radio network or the asynchronous mobile station receives data including an erroneous fragment , a buffer in which the data is stored to be combined with retransmitted data is the buffer 121 and 221 included in the layer 1 120 and 220 of respective the asynchronous mobile station 100 and the asynchronous radio network 200 . each buffer 121 and 221 can be placed behind respective demodulation unit 122 and 222 . in case the data reception side requests data retransmission , a data transmission side needs to retransmit data that are previously transmitted to the data reception side . in this case , also there is needed a buffer for storing data that is used for data retransmission . each buffer 133 and 233 of respective upper layer 130 and 230 is used for this case . fig3 is a flow chart illustrating a method for retransmitting data using an upper layer message in accordance with the present invention . referring to fig3 , there is provided how the transmission side transmits to the reception side , via an upper layer , a first message including information of the time when retransmission data will be transmitted before the transmission side transmits the retransmission data to the reception side . steps s 301 to s 309 illustrate a procedure of processing data in case a reception side receives non - erroneous data . after a call connection , at the step s 301 , an upper layer 31 of a transmission side 30 transmits data to a buffer 32 of the upper layer 31 . at the step s 302 , the data are stored in the buffer 32 of the upper layer 31 and then supplied to a physical layer 33 of the transmission side 30 . the physical layer 33 transmits the data to the reception side . after receiving the data from the transmission side , at the step s 303 , a physical layer of the reception side transmits the data to a buffer 36 of the physical layer 35 . at the step s 304 , the data are stored in the buffer 36 and then supplied to a cyclic redundancy check ( crc ) unit 38 . the cyclic redundancy check unit 38 checks if the data stored in the buffer 36 are erroneous . if non - erroneous data are stored in the buffer 36 , at the step s 305 , the cyclic redundancy check unit 38 transmits to the buffer 36 a signal representing that the data need to be cleared from the buffer 36 . the reason is that the non - erroneous data need not be stored in the buffer . at the step s 306 , the cyclic redundancy check unit 38 transmits the data to an upper layer 39 . at the step s 307 , the upper layer 39 transmits to the transmission side 30 an ack ( acknowledgement ) signal representing that non - erroneous data was received . at the step s 308 , the physical layer 33 of the transmission side 30 receives the ack signal from the reception side 34 , and transmits the ack signal to the upper layer 31 of the transmission side 30 . at the step s 309 , the upper layer 31 transmits to the buffer 32 of the upper layer 31 a signal representing that the data transmitted to the reception side need to be cleared from the buffer 32 of the upper layer 31 . in the above steps , a procedure of demodulating the data at the physical layer 35 of the reception side 34 can be performed prior or after the step s 303 . steps s 310 to s 327 illustrate a procedure of processing data in case the reception side receives erroneous data . at the step s 310 , the upper layer 31 of the transmission side 30 transmits data to the buffer 32 of the upper layer 31 . at the step s 311 , the data are stored in the buffer 32 of the upper layer 31 and then supplied to the physical layer 35 of the transmission side 34 . the physical layer 35 transmits the data to the reception side . after receiving the data from the transmission side , at the step s 312 , the physical layer 35 of the reception side transmits the data to the buffer 36 of the physical layer 35 . at the step s 313 , the data are stored in the buffer 36 and then supplied to the cyclic redundancy check unit 38 . the cyclic redundancy check unit 38 checks if the data stored in the buffer 36 is erroneous . as a result of the check , if the data is erroneous , the cyclic redundancy check unit 38 doesn &# 39 ; t transmit the erroneous data to the upper layer 39 and the erroneous data remains stored in the buffer 36 of the physical layer 35 . in case the upper layer fails to receive the desired data during a predetermined time or the other data that are supposed to be received later than the desired data are received ahead , at the step s 314 , the upper layer 39 of the reception side 34 transmits to the transmission side 30 a nack ( negative acknowledgement ) signal representing that desired data are not received . at the step s 315 , the physical layer 33 of the transmission side 30 that receives the nack signal from the reception side 34 , transmits the nack signal to the upper layer 31 of the transmission side 30 . before the upper layer 31 transmits retransmission data requested from the reception side , at the step s 316 , the upper layer 31 generates information data and then transmits the information data to the physical layer 35 of the reception side 34 via the physical layer 33 of the transmission side 30 . the information data includes information about a retransmission time when the transmission side 30 will transmit the retransmission data to the reception side 34 , information about how the transmission side will perform data processing ( for example , a data coding rate , puncturing and so on ) or the like . at the step s 317 , the physical layer 35 of the reception side 34 transmits the information data from the transmission side 30 to the upper layer 39 of the reception side . at the step s 318 , the upper layer 39 analyzes the information data , selects necessary information to be used at the physical layer 35 and then transmits the necessary information to the physical layer 35 . at the step s 319 , the upper layer 31 of the transmission side 30 selects the retransmission data from the buffer 32 of the transmission side . at the step s 320 , the buffer 32 of the upper layer 31 transmits the retransmission data to the physical layer 33 and then the physical layer 33 transmits the retransmission data to the reception side . in this case , a way of processing the retransmission data , for example , a data coding rate and a puncturing , at the physical layer 33 is different from that of processing the data for the initial transmission from the transmission side to the reception side . also , the way of processing the retransmission data is required to conform to the information data that are transmitted to the reception side . accordingly , it is required that the information data are transmitted to the physical layer 33 earlier than the retransmission data . at the step s 321 , the physical layer 35 of the reception side 34 stores the retransmission data from the transmission side in the buffer 36 and then the buffer 36 transmits the retransmission data to a combiner 37 in order to combine the retransmission data with the erroneous data previously stored in the buffer 36 . at the step s 322 , the buffer 36 transmits the erroneous data to the combiner 37 . at the step s 323 , the combiner 37 performs combining the retransmission data with the erroneous data and the cyclic redundancy check unit 38 checks if the combined data are erroneous , and if not , transmits to the buffer 36 a clear signal representing that the combined data need to be cleared from the buffer 36 . at the step s 324 , the cyclic redundancy check unit 38 transmits the combined data to the upper layer 39 . at the step s 325 , the upper layer 39 transmits to the transmission side the ack signal representing that non - erroneous data was received . at the step s 326 , the physical layer 33 of the transmission side transmits the ack signal to the upper layer 31 of the transmission side . at the step s 327 , the upper layer 31 transmits to the buffer 32 of the upper layer 31 a clear signal representing that the retransmission data needs to be cleared from the buffer 32 . fig4 is a flow chart illustrating a method for retransmitting data using a tfci ( transport format combination indicator ) in accordance with the present invention . referring to fig4 , there is provided how the transmission side retransmits erroneous data to the reception side using the tfci including information indicating that currently transmitted data are retransmission data . a physical layer can interpret the tfci in a radio frame without the support of the other layer . steps s 401 to s 409 illustrate a procedure of processing data in case a reception side receives non - erroneous data . after a call connection , at the step s 401 , an upper layer 31 of a transmission side 30 transmits data to a buffer 32 of the upper layer 31 . at the step s 402 , the data are stored in the buffer 32 of the upper layer 31 and then supplied to a physical layer 35 of the transmission side 34 . the physical layer 35 transmits the data to the reception side . after receiving the data from the transmission side , at the step s 403 , a physical layer of the reception side transmits the data to a buffer 36 of the physical layer 35 . at the step s 404 , the data is stored in the buffer 36 and then supplied to a cyclic redundancy check ( crc ) unit 38 . the cyclic redundancy check unit 38 checks if the data stored in the buffer 36 is erroneous . if non - erroneous data is stored in the buffer 36 , at the step s 405 , the cyclic redundancy check unit 38 transmits to the buffer 36 a signal representing that the data can be cleared from the buffer 36 . the reason is that the non - erroneous data need not be stored in the buffer . at the step s 406 , the cyclic redundancy check unit 38 transmits the data to an upper layer 39 . at the step s 407 , the upper layer 39 transmits to the transmission side 30 an ack ( acknowledgement ) signal representing that the non - erroneous data were received . at the step s 408 , the physical layer 33 of the transmission side 30 that receives the ack signal from the reception side 34 , transmits the ack signal to the upper layer 31 of the transmission side 30 . at the step s 409 , the upper layer 31 transmits to the buffer 32 of the upper layer 31 a signal representing that the data transmitted to the reception side need to be cleared from the buffer 32 of the upper layer 31 . in the above steps , a procedure of demodulating the data at the physical layer 35 of the reception side 34 can be performed prior or after the step s 403 . steps s 410 to s 424 illustrate a procedure of processing data in case the reception side receives erroneous data . at the step s 410 , the upper layer 31 of the transmission side 30 transmits data to the buffer 32 of the upper layer 31 . at the step s 411 , the data is stored in the buffer 32 of the upper layer 31 and then supplied to the physical layer 35 of the transmission side 34 . the physical layer 35 transmits the data to the reception side . after receiving the data from the transmission side , at the step s 412 , the physical layer 35 of the reception side transmits the data to the buffer 36 of the physical layer 35 . at the step s 413 , the data is stored in the buffer 36 and then supplied to the cyclic redundancy check unit 38 . the cyclic redundancy check unit 38 checks if the data stored in the buffer 36 is erroneous . as a result of the check , if the data is erroneous , the cyclic redundancy check unit 38 doesn &# 39 ; t transmit the erroneous data to the upper layer 39 and the erroneous data remain stored in the buffer 36 of the physical layer 35 . in case the upper layer fails to receive the desired data during a predetermined time or the other data that are supposed to be received later than the desired data are received ahead , at the step s 414 , the upper layer 39 of the reception side 34 transmits to the transmission side 30 a nack ( negative acknowledgement ) signal representing that desired data was not received . at the step s 415 , the physical layer 33 of the transmission side 30 that receives the nack signal from the reception side 34 , transmits the nack signal to the upper layer 31 of the transmission side 30 . at the step s 416 , the upper layer 31 of the transmission side 30 selects the retransmission data from the buffer 32 of the transmission side . at the step s 417 , the buffer 32 of the upper layer 31 transmits the retransmission data to the physical layer 33 and then the physical layer 33 transmits the retransmission data to the reception side . in this case , a way of processing the retransmission data , for example , a data coding rate and a puncturing , at the physical layer 33 is different from that of processing the data that is transmitted initially from the transmission side to the reception side . information about the way of processing the retransmission data is included in the tfci . the physical layer 35 of the reception side can interpret the tfci without getting a support from the other layers . the retransmission data together with the tfci are transmitted to the reception side . at the step s 418 , the physical layer 35 of the reception side 34 stores the retransmission data from the transmission side in the buffer 36 . the buffer 36 determines if the stored data are the retransmission data by interpreting the tfci of the received data , and if the received data are the retransmission data , the buffer 36 transmits the retransmission data to a combiner 37 in order to combine the retransmission data with the erroneous data previously stored in the buffer 36 . at the step s 419 , the buffer 36 transmits the erroneous data to the combiner 37 . interpreting the tfci at the above step s 418 can be performed after or before storing the retransmission data in the buffer 36 of the physical layer 35 . at the step s 420 , the combiner 37 performs combining the retransmission data with the erroneous data and the cyclic redundancy check unit 38 checks if the combined data are erroneous , and if not , transmits to the buffer 36 a clear signal representing that the combined data need to be cleared from the buffer 36 , otherwise the logic flow returns to the step s 414 . at the step s 421 , the cyclic redundancy check unit 38 transmits the combined data to the upper layer 39 . at the step s 422 , the upper layer 39 transmits to the transmission side the ack signal representing that non - erroneous data were received . at the step s 423 , the physical layer 33 of the transmission side transmits the ack signal to the upper layer 31 of the transmission side . at the step s 424 , the upper layer 31 transmits to the buffer 32 of the upper layer 31 a clear signal representing that the retransmission data may be cleared from the buffer 32 . a procedure of demodulating the retransmission data from the transmission side at the physical layer 35 of the reception side 34 can be performed after or prior the step s 418 . in the hybrid arq types ii / iii in accordance with the present invention , there is provided an advantageous effect that erroneous data can be restored without a time delay since the reception side recognizes when the retransmission data will be transmitted thereto . also , the hybrid arq types ii / iii can be applied to a mobile communication system without modifying system hardware . although the preferred embodiments of the invention have been disclosed for illustrative purpose , those skilled in the art will appreciate that various modifications , additions , and substitutions are possible , without departing from the scope and sprit of the invention as disclosed in the accompanying claims .