METHOD FOR OPERATING ENHANCED RLC ENTITY AND RNC ENTITY FOR WCDMA AND SYSTEM THEREOF

1 . A method of processing data units in a mobile communications system, the method comprising:

receiving a first data unit from an upper layer;

generating a second data unit using the received first data unit and a header, wherein a size of the header is variable depending on a channel of the received first data unit; and

transferring the second data unit to a lower layer.

2 . The method of claim 1 , wherein the header comprises one or more necessary fields.

3 . The method of claim 1 , wherein the first data unit is a MAC-hs Service Data Unit (SDU) and the second data unit is a MAC-hs Protocol Data Unit (PDU).

4 . The method of claim 1 , wherein the channel is a logical channel.

5 . The method of claim 2 , wherein the one or more necessary fields include at least one of a VF(Version Flag) field, a SID(Size index identifier) field, a N(Number) field, a TSN(Transmission Sequence Number) field, a queue ID(Queue identifier) field, and a F(Flag) field.

6 . The method of claim 4 , further comprising:

determining the logical channel by using a C/T(Control/Traffic) field.

7 . The method of claim 4 , further comprising:

identifying the logical channel using a logical channel identifier.

8 . The method of claim 1 , wherein the lower layer is a physical layer.

9 . The method of claim 1 , wherein the channel is assigned to provide a VoIP(Voice of Internet Protocol) service.

10 . A method of processing data units in a mobile communications system, the method comprising:

receiving a first data unit from a lower layer;

identifying fields and a size of each fields from a header of the received first data unit, wherein the fields and the size of each fields were determined based on a channel that received a payload of the first data unit in a first entity;

generating a second data unit using the payload of the first data unit and the identified fields and the size of each fields in the header of the first data unit; and

transferring the second data unit to an upper layer.

11 . The method of claim 10 , wherein the first data unit is a MAC-hs Protocol Data Unit (PDU) and the second data unit is a MAC-hs Service Data Unit (SDU).

12 . The method of claim 10 , wherein the first entity is a Medium Access Control (MAC) entity in a transmitting side.

13 . The method of claim 10 , wherein each header field is extracted according to the size of each header field of the first data unit.

14 . The method of claim 10 , wherein the channel is a logical channel in a transmitting side.

15 . A method of processing data units in a mobile communications system, the method comprising:

receiving a first data unit from a first channel;

receiving a second data unit from a second channel;

determining one or more necessary fields and a size of each necessary field for each channel of the each received data unit;

generating a third data unit using the determined fields, the determined size of the each field, and the received first data unit and the second data unit; and

transmitting the third data unit to a lower layer.

16 . The method of claim 15 , wherein the first data unit and the second data unit are MAC-hs Service Data Units (SDUs) and the third data unit is a MAC-hs Protocol Data Unit (PDU).

17 . The method of claim 15 , wherein the first and second channel are logical channels.

18 . The method of claim 15 , wherein the lower layer is a physical layer.

19 . The method of claim 15 , wherein the one or more necessary fields include at least one of a VF(Version Flag) field, a SID(Size index identifier) field, a N(Number) field, a TSN(Transmission Sequence Number) field, a queue ID(Queue identifier) field, and a F(Flag) field.

20 . The method of claim 15 , wherein the first channel is assigned to provide a VoIP(Voice of Internet Protocol) service and the second channel is assigned to provide a internet browsing service.