HK1069498B - Wireless communication system having rlc layer of transparent mode and data processing method in the same - Google Patents

Description

Wireless communication system and data processing method thereof

The present application is a divisional application of the chinese patent application entitled "wireless communication system and data processing method thereof" with application number 01141535.5.

Technical Field

The present invention relates to a wireless communication system having a transparent mode RLC layer and a data processing method thereof.

Background

Much effort has been made to research and develop communication technologies capable of using multimedia without space-time limitation. The development of technologies including digital data processing and transmission has in the near future enabled the unification of wireless and wired communications with each other and the realization of real-time global data communication systems.

The development of digital data processing and transmission technology has made it possible to freely use information anytime and anywhere regardless of the technology used, such as network-based still images, real-time transmission of moving images, wired/wireless communication, and conventional voice communication.

These techniques will also include IMT-2000.

The RLC (radio link control) layer mentioned in the description of the present invention is the second layer of 3GPP, corresponding to the second layer of the OSI seven layer model, as a protocol layer for controlling the data link. The RLC entity classes used by 3GPP are mainly classified into Tr (transparent) mode and NTr (non-transparent) mode without RLC header.

The Ntr mode is further classified into an UM (non-acknowledgement) mode without an ACK (acknowledgement) signal from the receiving end, and an AM (acknowledgement) mode with an ACK (acknowledgement) signal from the receiving end. Therefore, currently used RLC modes are Tr, UM and AM.

Fig. 1 shows a data transmission apparatus in a wireless communication system having a Tr mode RLC layer.

The Tr mode without the RLC header attached is simpler than the entity structure of the NTr mode.

Referring to fig. 1, a data transmission apparatus having a Tr mode RLC layer 101 performs segmentation by a segmentation section 102 on the basis of a radio interface 100 to convert Service Data Units (SDUs) from an upper layer into Protocol Data Units (PDUs) of uniform size.

The segmented protocol data unit is stored in a transmission buffer 103 and then transmitted down to a MAC (medium access control) layer 104 through a logical channel.

Meanwhile, when the RLC layer 101 of the Tr mode transmits PDUs to the MAC layer 104, the PDUs are transmitted in TTIs (transmission time intervals).

In addition, the RLC layer 101 transmits PDUs by the number required by the MAC layer 104. For this purpose, the MAC layer 104 informs the RLC layer 101 of information on the number of PDUs to be received in each TTI through its STATUS information (MAC-STATUS-IND primitive).

In response to the information on the number of PDUs to be received in each TTI, the RLC layer 101 transmits the PDUs stored in the transmission buffer 103 to the MAC layer 104 corresponding to the number required by the MAC layer.

The PDU is transmitted to the data receiving apparatus 105 of the wireless communication system having the Tr mode RLC layer on the basis of the radio interface 100.

The reception apparatus 105 temporarily stores PDUs received on the basis of the radio interface 100 in the reception buffer 106. Then, each time a PDU constituting one complete SDU is received, the reception apparatus 105 transfers the PDU up to the upper layer in units of SDUs. I.e. the protocol data units are reassembled into SDUs in the assembly portion 107 for delivery to the upper layers.

The above-described related art has the following problems or disadvantages.

First, the MAC layer 104 of the transmitting apparatus multiplexes PDUs received from different RLC layers and then transmits the multiplexed PDUs to the physical layer PHY through one transport channel. In this case, in order to improve transmission efficiency, the MAC layer 104 adjusts the number of PDUs received from the RLC layers in each TTI differently, respectively.

However, it is difficult to guarantee that the transmission efficiency can be improved only by adjusting the number of PDUs received in each TTI. In order to improve transmission efficiency, it is preferable that both the PDU size and the number of PDUs received from each RLC layer in each TTI be adjusted. However, in the related art, it is difficult to adjust the size of the PDU in every TTI.

The data transmission apparatus having the Tr mode RLC layer according to the related art in fig. 1 segments a service data unit into protocol data units of uniform size in the RLC layer 101 and then stores the protocol data units in the transmission buffer 103. If a PDU of a different size than the PDU transmitted in the previous TTI is to be transmitted, the PDUs stored in the transmission buffer 103 must be reassembled into SDUs again.

Next, the reassembled SDU is segmented into new PDUs of the size required by the MAC layer 104, and the re-segmented PDUs are sent to the MAC layer 104.

In the above case, a method or apparatus for reassembling PDUs stored in the transmission buffer 103 into SDUs is required. Also, a method of segmenting the reassembled SDU into PDUs of the size required by the MAC layer 104 is required in this case.

Therefore, the structure of the RLC layer becomes complicated, and the transmission processing time of the protocol data unit increases.

Disclosure of Invention

Accordingly, the present invention is directed to a wireless communication system having a transparent mode RLC layer and a data processing method thereof that substantially obviate one or more problems due to limitations and disadvantages of the related art.

An object of the present invention is to provide a wireless communication system capable of processing protocol data units by changing the size of the protocol data units and the number thereof.

It is another object of the present invention to provide a method of processing a protocol data unit in a wireless communication system.

Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention may be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.

To achieve these objects and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, a communication apparatus having a transparent mode entity radio link control, RLC, according to the present invention includes: a transmission buffer storing at least one service data unit transmitted from an upper layer; and a segmentation module segmenting the service data unit received from the transmission buffer into at least one protocol data unit according to size information on the protocol data unit transmitted from the lower layer, and wherein the at least one protocol data unit is provided to the lower layer by the RLC layer.

A data processing method in a wireless communication device having a transparent mode entity radio link control, RLC, according to the present invention includes: storing at least one service data unit transferred from an upper layer in a transmission buffer; segmenting the service data unit received from the transmission buffer into at least one protocol data unit according to size information on the protocol data unit transmitted from a lower layer; and providing at least one protocol data unit to the lower layer.

Preferably, the radio link control layer operates in a transparent mode.

Preferably, the data is processed in units of service data units in the transmission data storage module. And storing the unsegmented service data unit in the transmit data storage unit.

Preferably, when transmitting the protocol data units of the radio link control layer to the MAC layer, the number and size of the protocol data units in each Transmission Time Interval (TTI) may vary.

It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention. In the drawings:

fig. 1 illustrates a data transmission apparatus in a wireless communication system having a Tr mode RLC layer according to the related art;

fig. 2 shows an RLC Tr entity structure according to the present invention; and

fig. 3 shows a procedure for processing transparent mode data between two wireless communication systems having a Tr mode RLC layer.

Detailed Description

The invention will be described in detail hereinafter with reference to preferred embodiments thereof, examples of which are illustrated in the accompanying drawings.

A Radio Link Control (RLC) layer of the transparent (Tr) mode is explained with reference to fig. 2.

Fig. 2 shows an RLC Tr entity structure according to the present invention.

Referring to fig. 2, the RLC of the data transmission apparatus in the wireless communication system has a transparent entity structure. The data transmission apparatus having a transparent entity structure includes the steps of: storing the service data unit in a transmission data storage module, segmenting the service data unit to divide it into at least one protocol data unit, and so on.

The MAC layer, which is a lower layer of the RLC layer, provides information on the size and number of protocol data units PDU to the RLC layer of the data transmission apparatus. The data transmission apparatus segments the service data unit into at least one protocol data unit having a required size according to the requirements of the MAC layer, and then transmits a number of protocol data units equal to the number required by the MAC layer to the MAC layer.

The data transmission apparatus in the wireless communication system having the RLC layer shown in fig. 2 includes a transmission buffer 202 as a transmission data storage module that stores service data units transmitted from an upper layer, and a segmentation module 204 that segments the service data units into at least one protocol data unit having a required size and unit according to an instruction signal from a lower layer such as the MAC layer and transmits the at least one protocol data unit to the MAC layer 203.

A procedure for transmitting data in a wireless data transmission apparatus having a transparent mode RLC layer according to the present invention is described in detail below.

The transparent mode RLC layer 201 of the radio interface 200 based wireless data transmission apparatus shown in fig. 2 stores service data units from an upper layer in a transmission buffer 202.

Meanwhile, the MAC203 transfers information on the number and size of Protocol Data Units (PDUs) to the transparent (Tr) mode RLC layer 201 through MAC STATUS indication information (MAC-STATUS-IND primitive), wherein the protocol data units are to be transmitted from the transparent mode RLC layer 201 to the MAC 203.

The segmentation module 204 of the transparent mode RLC layer (or RLC Tr entity) 201 segments a service data unit (SPU) into appropriate protocol data units without overhead (overhead) attached, according to the size of the protocol data unit (PDU size) required by the MAC 203. The method of the segmentation operation depends on when the service is established.

RLC service data units may be segmented, the allowed size of the RLC PDU depending on the transport format of the transport channel. The size of the RLC PDU is preferably decided in such a way that: the number of RLC PDUs multiplied by the size of the RLC PDU is the size of the RLC SDU.

All RLC PDUs carrying a single RLC SDU are transmitted in one transmission time interval. Also, only one segment of an RLC SDU is transmitted in one transmission time interval, and segments of other RLC SDUs are not transmitted in this transmission time interval.

If the RLC layer of the Tr mode does not perform a segmentation operation, one RLC PDU is used per RLC SDU, and more than one RLC SDU can be transmitted in one transmission time interval. However, the RLC PDUs should have the same size because of the limitation of the lower layer.

The RLC layer 201 of the Tr mode transmits PDUs to the MAC203 in every predetermined Transmission Time Interval (TTI).

In this case, the PDUs are transmitted to the MAC in an appropriate number and size according to the number of PDUs required by the MAC 203.

As described earlier, the MAC203 transfers information on the number and size of Protocol Data Units (PDUs) to the transparent (Tr) mode RLC layer 201 through MAC STATUS indication information (MAC-STATUS-IND primitive), wherein the protocol data units are to be transmitted to the MAC203 by the transparent mode RLC layer 201.

Upon receiving information on the number and size of Protocol Data Units (PDUs) from the MAC203 in each TTI, the RLC layer 201 converts the SDUs stored in the transmission buffer 202 into at least one PDU having a size required by the MAC layer 203 and then transmits the PDUs exactly by the number required by the MAC 203.

The PDU is transmitted to a data receiving apparatus having a Tr mode RLC layer based on the radio interface 200.

Meanwhile, the RLC layer 205 of the data receiving apparatus having the Tr mode RLC layer stores PDUs, which are received from the MAC layer through one of logical channels BCCH, CCCH, DCCH, PCCH, SHCCH, and DTCH based on the radio interface 200, in the reception buffer 206.

Next, upon receiving all PDUs constituting one complete SDU, the RLC layer 205 of the data receiving apparatus uploads the received data to an upper layer in SDU units through a transparent SAP (Tr-SAP).

That is, the PDUs stored in the reception buffer 206 are reassembled into RLC SDU units in the reassembly module 207 and then transmitted to an upper layer through a transparent SAP (Tr-SAP). The SDU is subjected to a reassembly procedure when segmented into PDUs in the data transmission apparatus.

How the reassembly step is performed depends on when the service is established.

In contrast to the prior art, the present invention is characterized in that unsegmented SDUs are stored in the transmission buffer 202, and the MAC203 informs the RLC layer 201 of the size and number of PDUs required when requesting the PDUs from the RLC layer 201.

It is further noted that the send buffer 202 processes the data units not in PDU units, but in SDU units.

The process of transmitting Tr pattern data is explained below with reference to fig. 3.

Fig. 3 illustrates a procedure for transmitting transparent mode data between two peer entities having a Tr mode RLC layer.

The procedure of transmitting Tr mode data is for transmitting data between two RLC peer entities operating in Tr mode. In fig. 3, the sender may be a UE (user entity) or a network, and the receiver may be a network or a UE.

If the upper layer requests Tr mode data, the transmitting side starts this process. In a data transfer ready state, a transmitting side converts a Service Data Unit (SDU) received from the upper layer or another upper layer into a PDU of a Tr pattern. If requested, the sender converts SDUs received from an upper layer into PDUs.

Available logical channels are DTCH, CCCH (uplink), SHCCH (uplink), BCCH, and PCCH. The type of logical channel depends on whether the RLC layer of the sender is located in the user plane DTCH or the control plane CCCH/BCCH/SHCCH/PCCH.

Multiple PDUs may be transmitted in each Transmission Time Interval (TTI). The lower layer, where the MAC is the sender, determines what PDU size to use and how many PDUs to send per transmission interval.

The PDU of the Tr pattern may be a complete SDU or a segment of an SDU. As previously mentioned, how the segmentation is done depends on when the service is established. No overhead or header is added to the PDU. But segmented according to the type of transport channel used with the particular transport format. The specific transport format informs the receiver how the segmentation is to be performed.

Upon receiving the Tr mode PDU, if the SDU is segmented, the receiving side reassembles the received PDU into the RLC SDU. The RLC layer of the receiving side then transmits the RLC SDU to the upper layer through the transparent SAP.

Thus, the present invention provides the following effects or advantages.

The data transmission apparatus having the Tr mode RLC layer according to the present invention stores service data units transmitted from an upper layer in a transmission buffer and then variably segments the stored service data units into protocol data units having a required number and size according to information from a MAC, which is a lower layer.

Therefore, the present invention can efficiently transmit PDUs. Also, the present invention can smoothly transmit voice data having a variable length and packet data having a uniform length.

Further, the RLC layer of the transmitting apparatus segments the SDU into PDUs having the required number and size according to information from the MAC. Accordingly, the MAC can efficiently multiplex PDUs from different RLC layers, further improving the performance of data transmission.

The above embodiments are merely exemplary and are not to be construed as limiting the present invention. The teachings of the present invention can be readily applied to other types of apparatuses. The description of the present invention is intended to be illustrative, and not to limit the scope of the claims. Substitutions, modifications and variations may be readily made by those skilled in the art.

Claims (24)

1. A communication device having a radio link control, RLC, layer in a transparent mode, comprising:

a transmission buffer storing at least one service data unit transmitted from an upper layer; and

a segmentation module which segments the service data unit received from the transmission buffer into at least one protocol data unit according to information on a size of the protocol data unit transferred from the lower layer, wherein the at least one protocol data unit is provided to the lower layer by the RLC layer.

2. The communication device of claim 1, wherein the RLC layer receives information on the number of protocol data units that can be transmitted in one transmission time interval.

3. The communication device according to claim 2, wherein the information on the size and number of protocol data units is provided by a MAC-STATUS-IND primitive from a lower layer, wherein the lower layer comprises a medium access control MAC layer.

4. The communication device of claim 1, wherein the at least one protocol data unit is provided to the lower layer through a logical channel.

5. The communication device of claim 4, wherein the logical channel comprises a dedicated control channel DCCH or a dedicated traffic channel DTCH.

6. The communications device of claim 5, wherein the logical channel further comprises a common control channel CCCH or a shared channel control channel SHCCH.

7. The communication device of claim 5, wherein the logical channel further comprises a broadcast control channel BCCH or a paging control channel PCCH.

8. The communication device of claim 1 or 4, wherein the transmit buffer receives at least one service data unit through a transparent mode service access point.

9. The communication device of claim 4, wherein the at least one protocol data unit is transmitted to a peer entity of a receiving side.

10. The communication device of claim 1, wherein the at least one service data unit is segmented by the segmentation module according to when the service is established.

11. The communication device of claim 1, wherein the at least one service data unit is segmented by the segmentation module according to a transport format of a transport channel.

12. The communication device of claim 1, further comprising:

a buffer for receiving at least one transparent mode protocol data unit from a lower layer; and

a reassembly module for forming at least one RLC service data unit based on the at least one transparent mode protocol data unit provided by the buffer, the reassembly module providing the at least one RLC service data unit to an upper layer.

13. A data processing method in a wireless communication device having a transparent mode radio link control, RLC, layer, comprising:

storing at least one service data unit transferred from an upper layer in a transmission buffer;

segmenting the service data unit received from the transmission buffer into at least one protocol data unit according to information about the size of the protocol data unit transmitted from a lower layer; and

the at least one protocol data unit is provided to a lower layer.

14. The method of claim 13, further comprising providing information on the number of protocol data units that can be transmitted by a lower layer to the RLC layer in one transmission time interval.

15. The method of claim 14, wherein the information on the size and number of the protocol data unit is provided by a MAC-STATUS-IND primitive from a lower layer, wherein the lower layer includes a medium access control MAC layer.

16. The method of claim 13, wherein the at least one protocol data unit is provided to the lower layer through a logical channel.

17. The method of claim 16, wherein the logical channel comprises a dedicated control channel DCCH or a dedicated traffic channel DTCH.

18. The method of claim 17, wherein the logical channel further comprises a common control channel CCCH or a shared channel control channel SHCCH.

19. The method of claim 17, wherein the logical channel further comprises a broadcast control channel BCCH or a paging control channel PCCH.

20. The method of claim 13 or 16, wherein the transmit buffer receives at least one service data unit through a transparent mode service access point.

21. The method of claim 13, wherein at least one service data unit of the transmit buffer is segmented by a segmentation module to provide at least one protocol data unit according to when a service is established.

22. The method of claim 13, wherein the at least one service data unit is segmented by a segmentation module to provide at least one protocol data unit according to a transport format of a transport channel.

23. The method of claim 14, wherein no overhead is attached to each of the at least one protocol data unit.

24. The method of claim 16, wherein the at least one protocol data unit is transmitted to a peer entity of a receiving side.