Method and apparatus for transmitting and receiving data via media access control protocol in mobile communication system

Abstract

Disclosed is a method and an apparatus for transmitting and receiving data via a MAC protocol in a mobile communication system. The method includes inputting at least one service data unit (SDU) containing transmission data through a corresponding logical channel and generating at least one first protocol data unit (PDU) that includes said at least one SDU without including multiplexing information for identification of the logical channel, by a first transmission entity; acquiring the first PDU and generating a second PDU including the first PDU in a payload of the second PDU, by a second transmission entity that operates between the first transmission entity and a physical layer; inserting the multiplexing information for identification of the logical channel corresponding to said at least one first PDU into header information of the second PDU; and transmitting the second PDU through the physical layer. The method can reduce load due to additional processing, such as a bit operation or memory copying, in a receiver requiring high speed data transmission.

Description

Moreover, when a MAC-d PDU includes a C/T field having a size of 4 bits, even though a MAC header has a size corresponding to a multiple of one byte, the byte alignment is broken again, which causes unnecessary processing load within the UE.

Furthermore, in the case of employing the structure of FIG. 3, even if only two logical channels are multiplexed, the UE must perform the bit operation for 70 C/T fields, and network resources are wasted due to transmission of the C/T fields. Such waste of the network resources is more acute, given the fact that only a few logical channels are multiplexed under an actual radio environment. According to the embodiment described later, the MAC-d entity does not identify logical channels by using the C/T fields of the PDUs transmitted from a MAC-hs entity. Instead, the logical channels are identified in the MAC-hs entity itself. In other words, a field for identifying logical channels is inserted into a MAC-hs header.

FIG. 5 is a block diagram illustrating a MAC-d sub-layer structure of a UE side according to an embodiment of the present invention.

Referring to FIG. 5, in order to communicate with entities including a MAC-hs entity supporting HSDPA operation, a MAC-c/sh entity for control signaling, and a MAC-e/es entity for transmission and signaling of Enhanced uplink Dedicated Channel (E-DCH) for High Speed Uplink Packet Access (HSUPA), a MAC-d entity 502 includes a switching block 504, a deciphering block 508, C/T MUXs 506 and 510, a UL TFC selecting block 512, and a ciphering block 514. Compared to the structure of FIG. 1, when the MAC-hs entity operates in the structure of FIG. 5, the switching block 504 processes data directly received from the MAC-hs entity without passing through the C/T MUX 506.

The ciphering block 514 encodes MAC-d PDUs and the UL TFC selecting block 512 selects a TFC indicating transport formats of transmission channels used for UL transmission. The C/T MUXs 510 and 506 analyze header information of the MAC-d PDUs, so as to demultiplex the MAC-d PDUs into MAC-d SDUs or generate MAC-d PDUs by multiplexing the MAC-d SDUs with header information. The deciphering block 508 decodes the encoded MAC-d SDUs. The switching block 504 maps MAC-d SDUs (which are also called “MAC SDUs”) of a Dedicated Control Channel (DCCH) and a Dedicated Traffic Channel (DTCH), which are logical channels, to corresponding transmission channels according to the transmission channel types.

FIG. 6 is a block diagram illustrating a MAC-hs sub-layer structure of a UE side for identifying logical channels according to an embodiment of the present invention.

Referring to FIG. 6, in order to support an HSDPA operation between the MAC-d entity and a physical layer, a MAC-hs entity 602 includes disassembly blocks 604a and 604b (604), C/T MUXs 612a and 612b (612), reordering queues 606a and 606b (606), a reordering queue distribution block 608, and a Hybrid Automatic Repeat reQuest (HARQ) processor 610.

The HARQ processor 610 receives MAC-hs PDUs from the physical layer on an HS-DSCH for supporting HSDPA and performs an HARQ operation. Then, the HARQ processor 610 delivers the MAC-hs PDUs successfully received through the HARQ operation to the reordering queue distribution block 608. The reordering queue distribution block 608 analyzes header information of the MAC-hs PDUs and delivers the analyzed MAC-hs PDUs to the reordering queues 606 corresponding to the associated DCHs. The reordering queues 606 store the MAC-hs PDUs until the C/T MUXs 612 read the MAC-hs PDUs. The C/T MUXs 612 located between the reordering queues 606 and the disassembly blocks 604 refer to C/T fields contained in MAC-hs headers of the MAC-hs PDUs, so as to identify and demultiplex MAC-hs SDUs contained in the MAC-hs PDU based on corresponding logical channels. The disassembly blocks 604 disassemble the demultiplexed data delivered from the C/T MUXs 612 into MAC-hs SDUs corresponding to each of the logical channels, and then outputs the disassembled MAC-hs SDUs as MAC-d PDUs to the MAC-d entity.

As described above, according to the embodiment of the present invention, a C/T field is inserted into each MAC-hs header, and a MAC-hs entity identifies the multiplexed logical channels within a MAC-hs PDU by using the inserted C/T fields. Since MAC-d PDUs having the same size are used during one TTI for the logical channels, the MAC-d PDUs of the logical channels identified by the C/T fields have the same size. Therefore, MAC-d PDUs included in a data part corresponding to one logical channel identified by a C/T field have the same SID/N/F field values.

As described above, the MAC-hs entity performs identification of the logical channels. Therefore, the MAC-d PDU does not have to contain header information for identification of logical channels. FIG. 7 illustrates a MAC-d PDU format without a header for identification of logical channels according to an embodiment of the present invention. Referring to FIG. 7, the MAC-d PDU includes only a MAC SDU 702 corresponding to an RLC PDU without header information. Therefore, the MAC-d PDU has the same size as the MAC-hs SDU.

FIG. 8 illustrates a format and a function of a MAC-hs PDU containing multiplexing information for identification of logical channels within its header according to an embodiment of the present invention.

Referring to FIG. 8, the MAC-hs PDU includes a MAC-hs header 802 and a MAC-hs payload 804. The MAC-hs payload 804 contains a plurality of MAC-hs SDUs (i.e. MAC-d PDUs) corresponding to multiple logical channels, and the MAC-hs header 802 contains format and multiplexing information concerning the MAC-d PDUs. The MAC-hs payload 804 optionally contains a padding for byte alignment of the entire MAC-hs PDU. Information fields contained in the MAC-hs header 802 are as follows.

• • VF 810 has a length of 1 bit and indicates a protocol version for a MAC-hs PDU format.
  • Queue ID 812 has a length of 3 bits and identifies reordering queues of a receiving side.
  • TSN 814 has a length of 6 bits and indicates a sequence number used to reorder MAC-hs PDUs.
  • SID 820 has a length of 3 bits and indicates the same size of successive MAC-d PDUs.
  • The number of MAC-d PDUs (N) 822 has a length of 7 bits and indicates the number of successive MAC-d PDUs with the same size.
  • F 824 has a length of 1 bit and indicates if there exists a further information field constituting the MAC-hs header 802. When the F field 824 has a value of “1”, this implies the end of the MAC-hs header 802.
  • C/T field (CT) 826 has, for example, a length of 4 bits and identifies the logical channels when multiple dedicated logical channels are mapped to the same MAC-d flow (i.e. HS-DSCH).

Herein, the combination of the SID field 820, the N field 822, the F field 824, and the C/T field 826 represents a format of each of the multiplexed logical channels. The combination is repeated within the MAC-hs header 802 as many times as the number of multiplexed logical channels. By using the structure of the MAC-hs header 802 as described above, it is possible to construct the MAC-d PDU format while identifying logical channels, even without repeatedly using a plurality of identical fields for multiple MAC-d PDUs of one logical channel.

The order of the information fields located in the above-described combination can be variously selected according to the design of a system. As shown in FIG. 8, the C/T field 826 is present within the MAC-hs header, and the MAC-hs entity identifies logical channels multiplexed within the MAC-hs PDU by using the C/T field 826.

A Header Padding (HP) field 830 is appended to the end of the MAC-hs header 802. The HP field 830 is a variable field having a bit size of 0 to 7. The bit size is determined from among values of 0 to 7 such that the entire MAC-hs header has a size corresponding to a multiple of one byte (8 bits). All of the bit values contained in the HP field 830 usually have a value of zero (all ‘0’). The end of the MAC-hs header 802 except for the HP field 830 is identified by an F field having a value of “1”. Therefore, a UE can recognize that the first MAC-hs SDU (i.e. MAC-hs payload 804) starts from the first byte directly following the F field having a value of “1.”

Meanwhile, when the MAC-hs PDU does not include plural multiplexed logical channels, the MAC-hs header 802 does not have to contain C/T fields for identification of the logical channels. Therefore, a C/T field is set to have a particular value that is not used for identification of a logical channel, for example, “1111”, as a value for indicating “No multiplexing (Non MUX).” When a UE identifies that the first C/T field has a value of “1111”, the UE determines that there exists no more C/T field. For example, Table 1 below shows definition of values of the C/T field.

TABLE 1

C/T field definition

0000      LC 1
0001      LC 2
. . .     . . .
1110      LC 15
1111      Non Mux

FIG. 9 illustrates a format and a function of a MAC-hs PDU including no multiplexed logical channels according to an embodiment of the present invention.

Referring to FIG. 9, the MAC-hs PDU includes a MAC-hs header 902 and a MAC-hs payload 904. Since the MAC-hs PDU does not include multiplexed logical channels, the MAC-hs payload 904 contains MAC-hs SDUs (i.e. MAC-d PDUs) corresponding to one logical channel, and the MAC-hs header 902 contains format and multiplexing information for the MAC-d PDUs. The MAC-hs payload 904 optionally contains a padding for byte alignment of the entire MAC-hs PDU. Information fields contained in the MAC-hs header 902 are as follows.

• • VF 910 has a length of 1 bit and indicates a protocol version of a MAC-hs PDU format.
  • Queue ID 912 has a length of 3 bits and identifies reordering queues of a receiving side.
  • TSN 914 has a length of 6 bits and indicates a sequence number used to reorder MAC-hs PDUs.
  • SID 920 has a length of 3 bits and indicates the same size of successive MAC-d PDUs.
  • N 922 has a length of 7 bits and indicates the number of successive MAC-d PDUs with the same size.
  • F 924 has a length of 1 bit and indicates if there exists a further information field constituting the MAC-hs header 802. When the F field 924 has a value of “1”, this implies the end of the MAC-hs header 902.
  • CT field 926 has, for example, a length of 4 bits and identifies logical channels.

Herein, only one combination of the SID field 920, the N field 922, the F field 924, and the C/T field 926 exists within the MAC-hs header 302, and the C/T field 926 is set to “1111,” which indicates that no logical channel multiplexing is used, and the F field 924 is set to have a value of “1” in order to indicate that it is the end of the MAC-hs header.

A Header Padding (HP) field 930 is appended to the end of the MAC-hs header 902. The HP field 930 is a variable field having a bit size of 0 to 7. The bit size is determined from among values of 0 to 7 such that the entire MAC-hs header has a size corresponding to a multiple of one byte (8 bits).

A MAC-d transmission entity provided at a transmitter in order to support the MAC-hs formats as shown in FIGS. 8 and 9 delivers an RLC PDU (i.e. MAC SDU) provided from an RLC layer entity to a MAC-hs transmission entity without appending a C/T field to the RLC PDU, that is, without identifying a corresponding logical channel. Then, the MAC-hs transmission entity configures a MAC-hs PDU including MAC-d PDUs provided from at least one RLC layer entity, and inserts a C/T field for identifying each logical channel into a MAC-hs header within the MAC-hs PDU. Further, when the MAC-hs header is not byte-aligned, the MAC-hs transmission entity appends a header padding field having a size necessary for the byte alignment to the MAC-hs header. To this end, the MAC-hs transmission entity receives information required to set a C/T field, from the MAC-d transmission entity or directly from the RLC layer entity.

FIG. 10 is a flowchart showing an operation of a receiver according to an embodiment of the present invention.

Referring to FIG. 10, in step 1002, the receiver receives reordered MAC-hs PDU through the reordering queue. In step 1004, the receiver determines if logical channel multiplexing has been used, based on a value of the first C/T field (i.e. CT₁) contained in a MAC-hs header within the MAC-hs PDU. When the CT₁ has a value of “1111,” the receiver determines that the logical channel multiplexing has not been used, the receiver proceeds to step 1006 in which the receiver reads a combination of CT₁, SID₁, and N₁, (i.e. the first header information) from the MAC-hs header, stores the read combination, and then proceeds to step 1008.

On the other hand, when logical channel multiplexing has been used, the receiver initializes a variable “n” for identification of logical channels to zero in step 1012. Then, in step 1014, the receiver increases the value of the variable “n” by one. In step 1016, the receiver reads a combination of CT_n, SID_n, and N_n from the MAC-hs header and stores the read combination. Then, in step 1018, the receiver determines if an F_n field subsequent to the read combination of the information fields has a value of “1,” in order to determine if it is the end of the MAC-hs header. As a result of the determination in step 1018, when the F_n field does not have a value of “1”, the receiver returns to step 1014 in order to read a next information field of the MAC-hs header. Otherwise, the receiver proceeds to step 1008.

In step 1008, the receiver decodes at least one combination of the stored CT_k, SID_k, and N_k (wherein k=0, 1, . . . , n), identifies at least one MAC-d PDU contained in the MAC-hs PDU according to the decoded CT_k, SID_k, and N_k, and delivers the at least one MAC-d PDU to a MAC-d entity, which is a higher layer entity. In this case, the MAC-hs entity of the receiver delivers the C/T field extracted from the MAC-hs header to the MAC-d entity, so that the MAC-d entity can refer to the extracted C/T field in delivering the MAC-d PDU to an RLC layer entity through a corresponding logical channel. In step 1010, the receiver removes the information fields, the HP field, and the padding of the stored MAC-hs header, and then terminates the operation.

In the present invention as described above, it is possible to remove a bit operation and a bit offset managing operation, which may occur due to unaligned bytes in a header field, and it is possible to prevent waste of system resources due to memory copying, in a mobile communication system. That is, in the present invention, identification of logical channels is performed by a MAC-hs entity, and appending of a header padding (HP) field guarantees byte alignment for layer-2 PDUs. Moreover, the present invention can reduce load due to additional processing, such as a bit operation or memory copying, in a receiver requiring high speed data transmission.

While the present invention has been shown and described with reference to certain exemplary embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims

1. A method for transmitting data via a MAC (Media Access Control) protocol in a mobile communication system, the method comprising the steps of:

inputting at least one service data unit (SDU) containing transmission data through a corresponding logical channel and generating at least one first protocol data unit (PDU) that includes said at least one SDU without including multiplexing information for identification of the logical channel, by a first transmission entity;

acquiring the first PDU and generating a second PDU including the first PDU in a payload of the second PDU, by a second transmission entity that operates between the first transmission entity and a physical layer;

inserting the multiplexing information for identification of the logical channel corresponding to said at least one first PDU into header information of the second PDU; and

transmitting the second PDU through the physical layer.

2. The method of claim 1, wherein the header information of the second PDU is configured to achieve byte alignment.

3. The method of claim 1, wherein, when the second PDU includes only one first PDU from a single logical channel, the multiplexing information is set to have a predetermined value indicating that logical channel multiplexing is not used.

4. The method of claim 1, wherein the header information of the second PDU includes information of an identical size of said at least one first PDU, an N field indicating the number of first PDUs delivered from the logical channel, and an F field indicating if there exists a further information field constituting the header information.

5. The method of claim 4, wherein the header information of the second PDU further includes a Version Flag field indicating a protocol version of the second PDU, a Queue identifier field indicating a reordering queue of a receiver for storage of the second PDU, and a Transmission Sequence Number field of the second PDU.

6. The method of claim 1, wherein the header information of the second PDU includes multiplexing information and format information, which are not repeated for multiple PDUs from one logical channel.

7. A method for receiving data via a MAC protocol in a mobile communication system, the method comprising the steps of:

receiving, by a first reception entity, a first PDU including header information and a payload through a physical layer;

reading multiplexing information for identification of a logical channel corresponding to at least one second PDU contained in the payload and format information of said at least one second PDU, from the header information of the first PDU; and

identifying the second PDU from the payload based on the format information and delivering the identified second PDU to a second reception entity.

8. The method of claim 7, wherein the header information of the first PDU is configured to achieve byte alignment.

9. The method of claim 7, further comprising determining that the first PDU includes only one second PDU from only one logical channel, when the multiplexing information is set to have a predetermined value indicating that logical channel multiplexing is not used.

10. The method of claim 7, wherein the header information of the first PDU includes information of an identical size of said at least one second PDU, an N field indicating the number of second PDUs delivered from the logical channel, and an F field indicating if there exists a further information field constituting the header information.

11. The method of claim 10, wherein the header information of the first PDU further includes a Version Flag field indicating a protocol version of the first PDU, a Queue identifier field indicating a reordering queue of a receiver for storage of the first PDU, and a Transmission Sequence Number field of the first PDU.

12. The method of claim 7, wherein the header information of the first PDU includes multiplexing information and format information, which are not repeated for multiple PDUs from one logical channel.

13. An apparatus for transmitting data via a MAC protocol in a mobile communication system, the method comprising:

a first transmission entity for inputting at least one service data unit (SDU) containing transmission data through a corresponding logical channel and generating at least one first protocol data unit (PDU) that includes said at least one SDU without including multiplexing information for identification of the logical channel; and

a second transmission entity for acquiring the first PDU and generating a second PDU including the first PDU in a payload of the second PDU, inserting the multiplexing information for identification of the logical channel corresponding to said at least one first PDU into header information of the second PDU, and transmitting the second PDU through the physical layer, the second transmission entity operating between the first transmission entity and a physical layer.

14. The apparatus of claim 13, wherein the second transmission entity configures the header information of the second PDU to achieve byte alignment.

15. The apparatus of claim 13, wherein, when the second PDU includes only one first PDU from a single logical channel, the second transmission entity sets the multiplexing information to have a predetermined value indicating that logical channel multiplexing is not used.

16. The apparatus of claim 13, wherein the header information of the second PDU includes information of an identical size of said at least one first PDU, an N field indicating the number of first PDUs delivered from the logical channel, and an F field indicating if there exists a further information field constituting the header information.

17. The apparatus of claim 16, wherein the header information of the second PDU further includes a Version Flag field indicating a protocol version of the second PDU, a Queue identifier field indicating a reordering queue of a receiver for storage of the second PDU, and a Transmission Sequence Number field of the second PDU.

18. The apparatus of claim 13, wherein the header information of the second PDU includes multiplexing information and format information, which are not repeated for multiple PDUs from one logical channel.

19. An apparatus for receiving data via a MAC protocol in a mobile communication system, the apparatus comprising:

a first reception entity for receiving a first PDU including header information and a payload through a physical layer, reading multiplexing information for identification of a logical channel corresponding to at least one second PDU contained in the payload and format information of said at least one second PDU, from the header information of the first PDU, identifying the second PDU from the payload based on the format information, and outputting the second PDU; and

a second reception entity for delivering the second PDU to a higher layer entity.

20. The apparatus of claim 19, wherein the header information of the first PDU is configured to achieve byte alignment.

21. The apparatus of claim 19, wherein the first reception entity determines that the first PDU includes only one second PDU from only one logical channel, when the multiplexing information is set to have a predetermined value indicating that logical channel multiplexing is not used.

22. The apparatus of claim 19, wherein the header information of the first PDU includes information of an identical size of said at least one second PDU, an N field indicating the number of second PDUs delivered from the logical channel, and an F field indicating if there exists a further information field constituting the header information.

23. The apparatus of claim 22, wherein the header information of the first PDU further includes a Version Flag field indicating a protocol version of the first PDU, a Queue identifier field indicating a reordering queue of a receiver for storage of the first PDU, and a Transmission Sequence Number field of the first PDU.

24. The apparatus of claim 19, wherein the header information of the first PDU includes multiplexing information and format information, which are not repeated for multiple PDUs from one logical channel.

25. A method for delivering data by a communication device in a mobile communication system, the method comprising:

obtaining, by a first entity of the communication device, a plurality of service data units (SDUs);

generating, by the first entity of the communication device, a protocol data unit (PDU) comprising a header and a payload including the plurality of SDUs; and

delivering, by the first entity of the communication device, the PDU to a second entity of the communication device,

wherein the header of the PDU and the PDU are respectively byte aligned in length, and

wherein the header of the PDU includes a plurality of logical channel identifier fields corresponding to each of the plurality of SDUs, respectively, and a plurality of extension fields indicating whether more fields are present in the header or not.

26. The method of claim 25, wherein the header of the PDU further includes a plurality of length fields indicating length information of the plurality of SDUs.

27. A method for delivering data by a communication device in a mobile communication system, the method comprising:

receiving, by a first entity of the communication device, a protocol data unit (PDU) comprising a header and a payload including a plurality of service data units (SDUs);

identifying, by the first entity of the communication device, a plurality of logical channel identifiers corresponding to the plurality of SDUs, respectively, based on the header of the PDU;

identifying, by the first entity of the communication device, the plurality of SDUs, based on the header of the PDU; and

delivering, by the first entity of the communication device, the identified plurality of SDUs corresponding to the identified plurality of logical channel identifiers to a second entity of the communication device,

wherein the header of the PDU and the PDU are respectively byte aligned in length, and

wherein the header of the PDU includes a plurality of extension fields indicating whether more fields are present in the header or not.

28. The method of claim 27, wherein the header of the PDU further includes a plurality of length fields indicating length information of the plurality of SDUs.

29. An apparatus for delivering data in a mobile communication system, the apparatus comprising:

a first entity configured to obtain a plurality of service data units (SDUs), generate a protocol data unit (PDU) comprising a header and a payload including the plurality of SDUs, and deliver the PDU to a second entity; and

the second entity,

wherein the header of the PDU and the PDU are respectively byte aligned in length, and

wherein the header of the PDU includes a plurality of logical channel identifier fields corresponding to each of the plurality of SDUs, respectively, and a plurality of extension fields indicating whether more fields are present in the header or not.

30. The apparatus of claim 29, wherein the header of the PDU further includes a plurality of length fields indicating length information of the plurality of SDUs.

31. An apparatus for delivering data in a mobile communication system, the apparatus comprising:

a first entity configured to receive a protocol data unit (PDU) comprising a header and a payload including a plurality of service data units (SDUs), identify a plurality of logical channel identifiers corresponding to the plurality of SDUs, respectively, based on the header of the PDU, identify the plurality of SDUs, based on the header of the PDU, and deliver the identified plurality of SDUs corresponding to the identified plurality of logical channel identifiers, to a second entity; and

the second entity,

wherein the header of the PDU and the PDU are respectively byte aligned in length, and

wherein the header of the PDU includes a plurality of extension fields indicating whether more fields are present in the header or not.

32. The apparatus of claim 31, wherein the header of the PDU further includes a plurality of length fields indicating length information of the plurality of SDUs.