KR20040048167A - Processing unexpected transmission interruptions in a wireless communications system - Google Patents

Abstract

PURPOSE: A treatment for unpredicted transmission interruptions in a wireless communication system is provided to delay discard and interruptions of SDU(Service Data Unit) data in response to unpredicted data interruption events until a next TTI(Transmission Time Interval) or by submitting padding PDUs(Protocol Data Units) instead of PDUs for carrying substantial SDU data, thereby guaranteeing that TFC(Transport Format Combination) data requests can be always realized. CONSTITUTION: A wireless communication device(100) includes a processor(110) and a memory(120). The memory(120) has a program code(130) executed by the processor(110). The program code(130) consisting of an application layer(134), a layer 3 interface(133), a layer 2 interface(132), and a layer 1 interface(131) is used to realize a wireless communication protocol. The layer 2 interface(132) is divided into layers including an MAC(Medium Access Control) layer(144) and an RLC(Radio Link Control) layer(142). The RLC layer(142) communicates with the layer 3 interface(133), and receives layer 3 data in a type of SDUs stored in a buffer(143).

Description

PROCESSING UNEXPECTED TRANSMISSION INTERRUPTIONS IN A WIRELESS COMMUNICATIONS SYSTEM}

The present invention relates to the handling of unexpected scheduling interruptions in data transmission to a wireless device. More specifically, the handling of scheduling interruptions between a radio link control (RLC) layer and a medium access control (MAC) layer is contemplated.

Many communication protocols typically use a three-layered approach to communication. See FIG. 1. 1 is a block diagram of three layers in the communication protocol. In a typical wireless environment, first station 10 is in wireless communication with one or more second stations 20. Application 13 on the first station 10 composes message 11 and forwards the message 11 to layer 3 interface 12 to be delivered to the second station 20. The layer 3 interface 12 may also generate layer 3 signaling messages for the purpose of controlling layer 3 operations between the first station 10 and the second station 20. An example of the layer 3 signaling message is a request to cipher key changes, the key changes being the respective layer 3 interfaces 12 and 22 of both the first station 10 and the second station 20. Is caused by. The layer 3 interface 12 delivers either message 11 or layer 3 signaling message 12a to layer 2 interface 16 in the form of layer 2 service data units (SDUs) 14. Layer 2 SDUs 14 may be any size, and Layer 3 interface 12 may retain the data desired to be delivered to the second station 20, which may be data from signaling message 12a or application message 11. . Layer 2 interface 16 creates the SDUs 14 into one or more Layer 2 protocol data units (PDUs) 18. Each layer 2 PDU 18 is of a fixed size and is delivered to a layer 1 interface 19. The layer 1 interface 19 is a physical layer and transmits data to the second station 20. The transmitted data is received by layer 1 interface 29 of the second station 20 and reconstructed into one or more PDUs 28 and forwarded to the layer 2 interface 26. The Layer 2 interface 26 receives the PDUs 28 and assembles one or more Layer 2 SDUs 24 from them. The layer 2 SDUs 24 are carried up to the layer 3 interface 22. And this time, on the contrary, the layer 3 interface 22 may cause the layer 2 SDUs 24 to be identical to the original message 11 generated by the application 13 on the first station 10 or the original message generated by the layer 3 interface 12. It must be identical to the signaling message 12a and converted to one of the two Layer 3 signaling messages 22a handled by the Layer 3 interface 22. The received message 21 is delivered to application 23 on the second station 20. As an awareness of the terminology used throughout this disclosure, a PDU is a data unit used internally by a layer to transmit and receive information, while an SDU is a data unit delivered to or received from a higher layer. . Thus, a layer 3 PDU is exactly the same as a layer 2 SDU. Similarly, layer 2 PDUs may be referred to as layer 1 SDUs. For the purposes of the following disclosure, the abbreviated term “SDU” is used to refer to Layer 2 SDUs (ie, Layer 3 PDUs). And the term “PDU” should be understood as Layer 2 PDUs (ie, Layer 1 SDUs).

Of particular interest is the layer 2 interface, which acts as a buffer between the relatively high-end data transmission and reception requests of applications and the low-level requests of the physical transmission and reception process. do. See FIG. 2. 2 is a diagram of a transmit / receive process from a layer 2 perspective. Layer 2 interface 32 of transmitter 30, which may be either a base station or a mobile station, receives a string of SDUs 34 from layer 3 interface 33. SDUs 34 are sequentially aligned sizes from 1 to 5 and are unequal sizes, as indicated by unequal lengths in the figures. The layer 2 interface 32 converts the string of SDUs 34 into the string of PDUs 36. The layer 2 PDUs 36 are sequentially arranged from 1 to 4, all of the same length. The string of PDUs 36 is then sent to Layer 1 interface 31 for transmission. The reverse process occurs at receiver end 40. The receiver has a receiver layer 2 interface 42 that assembles the received string of layer 2 PDUs 46 into the received string of layer 2 SDUs 44 and may also be either a base station or a mobile station. Under special transport modes, the multi-layer protocol asserts that receiver layer 2 interface 42 will in turn assign SDUs 44 to layer 3 interface 43. That is, the layer 2 interface 42 should assign the SDUs 44 to the layer 3 interface 43 in the sequential order of the SDUs 44 starting with SDU 1 and ending with SDU 5. The order of SDUs 44 will not be confused and mixed up, and subsequent SDUs will not be delivered to Layer 3 until all previous SDUs have been delivered.

For line transmissions, this requirement is relatively easy to achieve. However, in the noisy environment of wireless transmissions, receiver 40, which may be a base station or a mobile station, often loses data. Moreover, under certain transmission modes, Layer 2 interface 32 of transmitter 30 may actually discard some of Layer 2 SDUs 34 after a predetermined amount of time if Layer 2 SDUs 34 have been excessively delayed. This is because of the so-called discard timers that are set for each SDU 34. When the discard timer for SDU 34 expires, SDU 34 is discarded and any PDUs 36 associated with SDU 34 are also discarded. Thus any layer 2 PDUs 46 in the received string of layer 2 PDUs 46 will be missed due to intentional abandonment from the transmitting side 30 or inappropriate reception on the receiver side 40. Thus, ensuring that Layer 2 SDUs 44 are in turn given may face significant challenges. Even in a non-sequential delivery mode where sequentially arranged delivery of SDUs 44 is not enforced, layer 2 SDU 44 cannot be granted until all of the layer 2 PDUs 46 it creates are correctly received.

Wireless protocols are carefully designed to focus on such issues. Generally speaking, there are two wide modes for sending and receiving data. Ie, AM transport (acknowledged mode transport) and UM transport (unacknowledged mode transport). For AM data, receiver 40 sends a special layer 2 grant signal to transmitter 30 to indicate successfully received layer 2 PDUs 46. Thus, AM PDUs 46 that were not successfully received may be retransmitted by transmitter 30 to ensure correct reception. Such a signal is not performed on the UM data. So there is no retransmission of UM PDUs 36. For the purposes of the present invention, UM data is equally applicable to this discussion, but AM data is used as an example. See FIG. 3 with reference to FIG. 1. 3 is a simplified block diagram of AM data PDU 50 as defined in the 3GPP ^™ TS 25.322 specification incorporated herein by reference. In general, there are two types of PDUs. That is, it is a control PDU or data PDU. Control PDUs are used by layer 2 interfaces 16 and 26 to control data transmission and reception protocols, such as the layer 2 grant signal mentioned above used to acknowledge received data. This is somewhat similar to the exchange of signaling messages 12a and 22a of layer 3 interfaces 12 and 22. However, layer 2 interfaces 16 and 26 do not interpret or recognize layer 3 signaling messages 12a and 22a. On the other hand, layer 2 interfaces 16 and 26 recognize layer 2 control PDUs and do not carry layer 2 control PDUs up to layer 3 interfaces 12 and 22. Data PDUs are used to carry SDU data. AM data is reassembled and given to Layer 3. Example PDU 50 is a data PDU and is divided into several fields, as defined by the Layer 2 protocol.

The first field 51 is a single bit indicating that the PDU 50 is either a data or control PDU. When data / control bit 51 is set (ie equal to 1), PDU 50 is indicated as a data PDU. The second field 52 is a sequence number field 52 and is 12 bits long. Consecutive PDUs 18, 28 subsequently have higher sequence numbers 52, and in this way the second station 20 can correctly reassemble Layer 2 PDUs 28 to form Layer 2 SDUs 24. For example, if the first PDU 18 is sent with a sequence number 52 such as 536, then the next PDU 18 will be sent with a sequence number 52 such as 537, and so on. The retransmitted PDU 18 may have a sequence number 52 of 535 indicating that it is subsequently inserted before PDU 18 having a sequence number of 536 even if it is received at a later time. By assembling the received data PDUs 50 in their correct subsequent order according to their respective sequence numbers 52, correct reconstruction of the SDU data is ensured. Sequence number 52 may allow retransmitted PDUs 50 to be inserted into their correct subsequent positions relative to other received PDUs 50. In this way, retransmission of data is supported. The single polling bit 53 follows the sequence number field 52 and, when set, an acknowledgment, which is a type of control PDU used by the receiver (i.e., the second station 20) to indicate the reception status of the received PDUs 28. Indicates that you must respond with an acknowledgment status PDU. The first station 10 sets the polling bit 53 to 1 to request the second station 20 to send an admission status control PDU. Bit 54 is retained and cleared to zero. The next bit 55a is an extension bit and, when set, indicates the presence of the following length indicator (LI). LI can be either 7 bits long or 15 bits long and is used to indicate the ending position of a layer 2 SDU within a layer 2 PDU 50. If a single SDU completely fills data area 58 of PDU 50, bit 55a will be 0, thereby indicating that no LI exists. However, in the example PDU 50 there are two Layer 2 SDUs ending at the Layer 2 PDU 50. That is, SDU_1 57a and SDU_2 57b. Therefore, there should be two LIs pointing to the respective ends of SDU_1 57a and SDU_2 57b. The PDU following the PDU 50 (ie subsequently as indicated later by sequence number 52) will retain the LI for SDU_3 57c. The first LI and LI1 are in the field 56a following the extended bit field 55a and indicate the end of SDU_1 57a. LI1 56a has a set extension bit 55b indicating the presence of another LI, LI2 in field 56b. LI2 56b indicates the ending position of SDU_2 57b. And has a cleared extension bit 55c which means there are no more LIs, so that data area 58 is starting. Data area 58 is used to hold actual SDU data.

See FIG. 4 in connection with FIG. 5. 4 is a more detailed block diagram of the prior art layer 2 interface 60. 5 is a timing diagram of transmission time intervals (TTIs) 72. Layer 2 interface 60 is in communication with a medium access control (MAC) layer 64 and includes radio link control (RLC) on its top. Such an arrangement can be found, for example, in the 3GPP ^™ specification TS 25.321 V3.9.0, incorporated herein by reference. The MAC layer 64 acts as an interface between the RLC layer 62 and the layer 1 interface 61. From a high-layer perspective (RLC layer 62 and higher layers), many channels can be established, each with its own carrying parameters. However, functionally, these channels should be integrated into a single stream for presentation on physical layer 1 interface 61. This is one of the main purposes of the MAC layer 64. The MAC layer 64 divides the transmission of PDUs 63 that the MAC layer 64 receives from each RLC layer 62 by a series of transmission time intervals (TTIs) 72 for the channel. For each channel, all TTI 72s for that channel have the same interval length as other TTIs 72 for that channel, such as 20 millisecond (ms) intervals. However, TTIs 72 may vary on a per channel basis, ie in duration from RLC layer 62 to RLC layer 62. For the present discussion, even if multiple channels are possible, only a single channel (ie, a single RLC layer 62) is intended. Within the time period of each TTI 72 for the channel, the MAC layer 64 sends a set 74 transport blocks 74a to the transmitted layer 1 interface 61. Set 74 of transport blocks 74a consists of a predetermined number of transport blocks 74a. Each transport block 74a includes one RLC PDU 75 and may optionally carry a MAC header 76. Within TTI 72, the transport blocks 74a in RLC PDUs 75 and TTI 72 are all the same length. The number of RLC PDUs 75 (ie, transport blocks 74a) in each transport block set 74 between TTIs 72 may vary. For example, in FIG. 5, the first TTI 72 transmits six PDUs 75 and the subsequent TTI 72 transmits three PDUs 75. The actual data size of PDUs 75 can also vary from TTI 72 to TTI 72. However, it is always the same within each TTI 72. In conclusion, prior to transmission for each TTI 72, MAC layer 64 informs RLC layer 62 the number of PDUs 75 required for TTI 72 and the size requirements for PDUs 75 within the TTI 72. This is referred to as transport format combination (TFC) selection and is used to schedule the transmission of data from RLC layer 62 to MAC layer 64. TFC selection turns MAC layer 64 into physical layer 1 61 by manipulating the various needs of RLC layers 62 for the most efficient stream data. The RLC layer 62 creates the SDUs 65a contained in the buffer 65 and is made up of properly sized PDUs 65b and delivers the required number of PDUs 65b to the MAC layer 64 as required by the TFC selection. As mentioned, the MAC layer 64 may optionally add a MAC header 76 to each RLC PDU 75 to generate transport blocks 74a for transport block set 74. Then, the transport block set 74 containing PDUs 65b is sent to layer 1 interface 61 for transmission.

See FIG. 6 with reference to FIG. 4. 6 is a timing diagram for TFC selection according to the prior art. In order to send at least some of the SDU data 65a in TTI 82, TFC selection is performed at TTI 81 immediately preceding TTI 82. Within the TTI 81, the RLC layer 62 gives RLC entity information 84 to the MAC layer 64. RLC entity information 84 tells MAC layer 64 how much SDU data 65a RLC layer 62 is waiting for transmission. MAC layer 64 responds to RLC entity information 84 with TFC data request 86. TFC data request 86 instructs RLC layer 62 of the number of PDUs 65b to submit to MAC layer 64. Thus, the size of PDUs 65b is submitted. This may or may not be sufficient to cover all of the SDU data 65a. If not enough, the RLC layer 62 will have to perform another TFC selection procedure in TTI 82 to transmit the remaining SDU data 65a in the subsequent TTI 83. If sufficient, RLC layer 62 splits the appropriate number of SDUs 65a into the required number of properly sized PDUs 65b. These PDUs 65b are delivered as block 88 to the MAC layer 64. Within TTI 82, MAC layer 64 processes block 88 for delivery to layer 1 interface 61. And TFC selection is repeated in TTI 82 for data transmission in TTI 83. SDUs 65a divided into PDUs 65b may be removed from the buffer 65.

SDUs may also be removed from buffer 65 due to timeout. Each SDU 65a may have an expiration time tracked by a discard timer. If the discard timer indicates that SDU 65a has exceeded its expiration time, the expired SDU 65a is removed from the buffer 65 and so is no longer needed for transmission. From the perspective of RLC layer 62, this is an externally random event that can occur at any time. In particular, such a discarding event may occur after the submission of RLC entity information 84 and places RLC layer 62 to have less (or even no) SDU data 65a than indicated in RLC entity information 84. However, once the MAC layer 64 responds to the RLC entity information 84 with the TFC data request 86, the RLC layer 62 must provide the appropriate block 88 with the required number of sized PDUs 65b. Failure to do so can lead to software failure of the wireless device. This is a threshold in the scheduling of data transmission between RLC layer 62 and MAC layer 64 and has been described in the prior art. If SDU 65a should be discarded due to timeout from the discard timer, and if RLC layer 62 already indicates MAC layer 64 that SDU 65a is ready for transmission in RLC entity information 84, then the actual SDU 65a Discarding is delayed up to TTI 82. By doing so, the RLC layer 62 is guaranteed to have enough SDU data 65a to form block 88. If an expired SDU 65a is not required for block 88, the expired SDU 65a may be safely discarded at TTI 82 before the next TFC selection event for TTI 83.

However, other unexpected data interrupt events may occur, which the prior art cannot handle. Reference is again made to FIG. 1 with reference to FIGS. 4 and 6. Most of these unexpected data interrupts are the result of command primitives sent from layer 3 interface 12 to layer 2 interface 16. Thus, data interruptions are not expected from the perspective of RLC layer 62. These include the stop, suspend, and re-establish command primitives. In addition, layer 2 reset events may also be sources of unexpected data interrupts. Layer 3 interface 12 begins a stop operation on layer 2 interface 16 when layer 3 interface 12 decides to change the base stations. The stop event requires that Layer 2 interface 12 immediately stop sending SDU data 65a. Thus, even if the TFC data request 86 is pending, PDUs 65b are effectively drawn from being delivered to MAC layer 64. The re-establish operation is initiated by layer 3 interface 12 with a reestablishment command primitive sent from layer 3 interface 12 to layer 2 interface 16 to restablishment the channel. When the name of the command primitive indicates, the channel is fully shut down and reestablished. All SDU data 65a, and associated PDUs 65b, are necessarily discarded when the channel is shut down. Again, this may put MAC layer 64 hanging from the unrealized TFC data request 86 for the reestablished channel. The suspend operation is performed by layer 3 interface 12 when layer 3 interface 12 determines to change the ciphering configuration between first station 10 and second station 20. The suspend primitive is propagated from layer 3 interface 12 to layer 2 interface 16 with the parameter "n". The parameter "n" instructs the layer 2 interface to stop transmitting data after "n" more PDUs 65b have been sent. With regard to PDUs 65b, the purpose of the parameter “n” is to allow sufficient time for the first station 10 to perform ciphering key synchronization with the second station 20. In general, if "n" is large enough, RLC layer 62 will have enough warnings to be able to "pre-plan" and will not leave TFC data request 86 unrealized. However, if "n" is small, RLC layer 62 will have to pull PDUs 65b already scheduled for transmission, so it will not be able to fulfill TFC data request 86. Finally, the reset operation is performed by layer 2 interface 16 when communication errors are detected over the channel. The errors are inherently unexpected events, and either the first station 10 or the second station 20 can initiate a reset operation. The reset operation requires that all state variables and all buffers for the channel be cleared and set to default values. Thus, SDUs 65a and PDUs 65b can be removed under a reset operation, which can be left to hang MAC layer 64 and wait for a response from TFC data request 86.

It is a primary object of the present invention to provide a method and associated system for handling unexpected transmission interruptions between a radio link control (RLC) layer and a medium access control (MAC) layer in a wireless communication system.

1 is a block diagram of a three-layer communication protocol,

2 is a simplified diagram of a transmit / receive process from a layer 2 perspective,

3 is a block diagram of an acknowledged mode (AM) protocol data unit (PDU),

4 is a more detailed block diagram of a prior art layer 2 interface,

5 is a timing diagram of transmission time intervals,

6 is a timing diagram for data transmission scheduling according to the prior art,

7 is a block diagram of a wireless communication device in accordance with the present invention;

8A is a detailed block diagram of an AM padding PDU;

8B is a detailed block diagram of an unacknowledged mode padded PDU, and

9 is a timing diagram for data transmission in accordance with the present invention.

* Description of the symbols for the main parts of the drawings *

RLC layer: 142

RLC Entity Information: 164

MAC layer: 144

Buffer: 143

In brief summary, a preferred embodiment of the present invention discloses a method and system for data scheduling between a radio link control (RLC) layer and a medium access control (MAC) layer in a wireless communication device. According to the method of the present invention, the RLC layer provides RLC entity information to the MAC layer. RLC entity information indicates that the RLC layer has service data unit (SDU) data to be transmitted. After providing RLC entity information, the RLC layer receives an unexpected data interrupt requiring the RLC layer to discard SDU data. After unexpected data interruption, the MAC layer requests at least one protocol data unit (PDU) from the RLC layer in response to the RLC entity information. The RLC layer then submits at least one padding PDU to the MAC layer in response to the MAC request. The padded PDU is submitted in place of the discarded SDU data. Alternatively, the affected SDU data is not discarded until the next transmission time interval (TTI).

It is an advantage of the present invention that by providing an appropriate amount of data at the MAC layer at all times regardless of data transfer interruptions, the MAC layer data request is always realized and so the risk of software instability is avoided.

After reading the following detailed description of the preferred embodiment illustrated in the various figures, the various objects of the present invention will no doubt become apparent to those skilled in the art.

In the following description, transmitters and receivers may include cellular telephones, personal data assistants, personal computers, or other devices using a wireless communication protocol. Although the methods of the present invention are applicable to other wireless systems, a wireless communication protocol is contemplated as discussed in the background of the invention. Differences between the prior art and the following publications constituting the present invention will be readily apparent to those skilled in the art through appropriate modifications of the prior art in accordance with the disclosure herein.

See FIG. 7. 7 is a block diagram of a wireless communication device 100 in accordance with the present invention. The wireless communication device 100 includes a processor 110 and a memory 120. The memory 120 holds program code 130 executed by the processor 110. Of course, other factors obvious to those skilled in the art are required for the device 100. However, it is not suitable for the present invention and is ignored for simplicity. Program code 130 including application layer 134, layer 3 interface 133, layer 2 interface 132, and layer 1 interface 131 is used to implement a wireless communication protocol. As well as various hardware / software interface considerations for the implementation of layer 1 interface 131, other arrangements are possible for how processor 110 and memory 120 and program code 130 correlate with the two. The block diagram indicated in FIG. 7 is merely the simplest but never unique arrangement. Regardless of the aspects related to the implementation, the wireless communication protocol itself, in particular the layer 2 interface 132, is of primary interest.

Layer 2 interface 132 is divided into layers that themselves include radio link control (RLC) layer 142 over medium access control (MAC) layer 144. The RLC layer 142 communicates with the layer 3 interface 133 and receives layer 3 data in the form of service data units (SDUs) stored in the buffer 143. RLC layer 142 receives command primitives such as suspend, stop, and re-establish primitives previously discussed from layer 3 interface 133. RLC layer 142 uses SDUs 141 to generate protocol data units (PDUs) 145 that are sent to MAC layer 144 for transmission. The size and number of PDUs 145 delivered to MAC layer 144 is dictated by the transport format combination (TFC) data request sent from MAC layer 144 to RLC layer 142. After the RLC layer 142 indicates that there is SDU data 141 to be delivered, the MAC layer 144 sends a TFC data request to the RLC layer 142. Information indicating that the RLC layer 142 has SDU data 141 to be delivered comes in the form of RLC entity information.

In a first embodiment, it is the method of the present invention that the RLC layer 142 provides at least one padding PDU 150 to the MAC layer 144 to realize TFC data requests from the MAC layer 144. Padding PDU 150 does not hold any actual SDU data 141, and is used when SDU data 141 is discarded because of unexpected data interruption. See Figure 8A. 8A is a detailed block diagram of padding PDU 150. Padding PDU 150a is a standard AM data PDU, so data / control bit 151a is set (ie equal to 1). Sequence number field 152a is a standard sequence number, and polling bit 153a is set or cleared as determined by Layer 2 interface 132 for status polling. Field 154a remains zero or is cleared. And the subsequent extension bit 155a is always set to indicate the following length indicator LI 156a. However, LI 156a is a string of 1s and holds a special code that far exceeds the length of data area 158a. The actual bit size of LI 156a depends on the LI size of the RLC entity and can be either 7 or 15. In Fig. 8A, the LI size of 15 bits is shown. The special LI 156a indicates that the rest of PDU 150a is padded and holds undefined information that can be ignored. Nevertheless, the first bit after LI 156a, i.e. extension bit 157a, should be cleared to zero for simple consistency indicating that SDU data area 158a is started. The contents of the SDU data area 158a are undefined and are insignificant fillers. Note that under UM transport, UM data PDUs will be used for padding. 8B is a block diagram of a UM data padding PDU 150b. UM data padding PDU 150b has only a 7-bit sequence number field 152b, which is relatively simpler in structure, followed by extension bit 155b set to 1, and 7-bit LI 156b is used to indicate subsequent padding. The bits are set to one. And the last extension bit 157b must be cleared to zero for consistency. The actual bit size of LI 156b depends on the “largest UMD PDU size” of UM RLC entity 142 configured by higher layer 133, and can be either 7 or 15. In Fig. 8B, a LI size of 7 bits is shown. As before, since the entire PDU 150b is a padding PDU, the contents of the SDU data area 158b are not defined and can hold anything.

The preferred embodiment uses padding PDUs 150 (PDUs 150a for AM RLC entity and PDUs 150b for UM RLC entity) to serve as replacement PDUs 150. The replacement PDUs 150 serve as a filler to provide MAC layer 144 with the necessary number of correctly sized PDUs for realizing the TFC data request from MAC layer 144.

See Figures 9, 8A, and 8B. 9 is a timing diagram for data transmission according to the present invention. As previously described, MAC layer 144 assigns RLC layer 142 a series of transmission time intervals (TTIs) of the same duration. In order to affect the data transmission in TTI 162, data scheduling by TFC selection is performed in previous TTI 161. To begin TFC selection, RLC layer 142 sends RLC entity information 164 to MAC layer 144. As previously mentioned, RLC entity information 164 indicates to MAC layer 144 how much SDU data 141 the RLC layer 142 has in buffer 143 waiting for transmission. After some time thereafter, MAC layer 144 responds to RLC entity information 164 with TFC data request 166. The TFC data request 166 indicates that the RLC layer 142 submits to the MAC layer 144 the number of PDUs 145 and the size that the PDUs 145 should have. The RLC layer 142 then divides the SDUs 141 into PDUs 145 that meet the requirements of the TFC data request 166 and submits the PDUs 145 as a block 168 to the MAC layer 144. This completes the TFC selection for TTI 162, where the TFC selection for TTI 163 is performed.

Unexpected data interruption may occur at any time between the submission of TFC entity information 164 to MAC layer 144 and the submission of block 168 of PDUs 145 to MAC layer 144. For the first embodiment method, unexpected data interruption may be due to a discard timer that causes one or more SDUs 141 to be discarded for UM or AM RLC entities; May be due to suspend, stop and re-establish operations initiated by command primitives from Layer 3 interface 133 for UM or AM RLC entities; Or due to a layer 2 AM RLC reset operation. For example, an unexpected data interruption may occur at time 169a preceding the TFC data request 166, or may occur at time 169b immediately after the TFC data request. In either case, the unexpected data interrupt 169a or 169b places the RLC layer 142 to have insufficient SDU data 141 to correctly meet the TFC data request 166. The RLC layer 142 constitutes a sufficient number of correctly sized padded PDUs 150 to achieve a balance of TFC data requirements 166. For example, at time 169b the re-establish command primitive from layer 3 interface 133 causes the SDU data 141 in buffer 143 to be discarded or interrupted for transmission, and the TFC data request 166 from MAC layer 144 is sized. If 5 PDUs of 220 octets in each are required, the RLC layer 142 configures 5 padded PDUs 150 of 220 octets in size and submits them to the MAC layer 144 as a block 168 to realize the TFC data request 166. will be. Thus, the 5-padded PDUs 150 will replace the SDU data 141 discarded or interrupted by the unexpected data interrupt 169b from the re-establish operation. As another example, a discard event from the discard timer 133d at layer 3 interface 133 may cause SDU 141d to be discarded. The discarded SDU 141d may have an RLC layer 142 in which one PDU is short in order to realize the TFC data request 166 ordered of 8 PDUs each 150 octets in size. In this case, the RLC layer 142 configures one padding PDU 150 to replace the discarded SDU data 141, combines it with the other correctly formed data PDUs 145, and blocks the entirety to realize the TFC data request 166. Submit as.

Above, padded PDUs are used as replacement PDUs to fill in place of SDU data that is no longer available. However, other types of PDUs other than simply padded PDUs may be used as replacement PDUs. For example, under AM transport, an illegal PDU with a reserved bit 154a set may be used as a replacement PDU. Alternatively, previously transmitted old PDUs may also be used as replacement PDUs. What is important is that some type of PDUs are submitted to the MAC layer in an appropriate number and size to realize the TFC data request.

In the second embodiment of the present invention, if an unexpected data interrupt occurs after the RLC entity information 164 has been submitted to the MAC layer 144, it should be discarded or interrupted for transmission by the unexpected data interrupt. The SDU data 141 is not discarded or interrupted until the next TTI interval 162. The unexpected data interruption includes suspend, stop and re-establish operations initiated by command primitives from layer 3 interface 133 for the UM or AM RLC entity, or layer 2 AM RLC reset operation. For example, an AM RLC reset operation may occur at time 169a or 169b to cause all SDU data 141 and all PDUs 145 to be discarded immediately. However, according to the second embodiment method, discarding of data that may be SDUs 141 or PDUs 145 is delayed until the next TTI 162 so that the RLC layer 142 has sufficient SDU data 141 to realize the TFC data request 166. do. RLC layer 142 is not limited by the time period for submitting RLC entity information to MAC layer 144 if data interruption occurs after block 168 is submitted to MAC layer 144 to complete TFC data request 166, and if If data interruption also occurs before submission of RLC entity information 170 in the next TTI 162, both SDU data 141 and PDU data 145 may be discarded.

In contrast to the prior art, the present invention ensures that TFC data requirements are always realized. This can be handled by submitting padding PDUs instead of PDUs carrying the actual SDU data or by delaying the discard or interruption of the SDU data in response to an unexpected data interrupt event until the next TTI. By ensuring that TFC data requirements are always realized, unexpected software problems can be avoided and the operational stability of the wireless communication device can be improved.

Those skilled in the art will readily appreciate that numerous modifications and variations of the device may be made while retaining the teachings of the present invention. Accordingly, the above disclosure should be treated as limited only by the scope and scope of the appended claims.

Claims (20)

A method of processing unexpected data interruption in data transmission scheduling between a radio link control (RLC) layer and a media access control (MAC) layer in a wireless communication device, wherein the unexpected data interruption is an RLC entity. After information is provided by the RLC layer to the MAC layer, The RLC layer submitting a suitable number of alternate protocol data units (PDUs) to the MAC layer in place of service data unit (SDU) data discarded or interrupted in response to a data request by the MAC layer. A method of handling unexpected data interruption, characterized in that. According to claim 1, The unexpected data interruption may include a discard timer, a reset operation, a suspend operation, a stop operation, or a re-establish operation. Because of the unexpected data interruption. According to claim 1, And the replacement PDUs are padding PDUs. A method for data scheduling between a radio link control (RLC) layer and a medium access control (MAC) layer in a wireless communication device, the method comprising: The RLC layer providing RLC entity information to the MAC layer, wherein the RLC entity information indicates that the RLC layer has service data unit (SDU) data to be transmitted; Providing to the MAC layer; After providing the RLC entity information, receiving an unexpected data interrupt requesting the RLC layer to discard or interrupt the transmission of the SDU data; After the unexpected data interruption, the MAC layer requesting at least one protocol data unit (PDU) from the RLC layer in response to the RLC entity information; And The RLC layer submitting at least one replacement PDU to the MAC layer in response to the MAC request; And wherein the at least one alternate PDU is submitted in place of the discarded or interrupted SDU data. 18. The method of claim 1, wherein the alternate PDU is submitted in place of the discarded or interrupted SDU data. The method of claim 4, wherein The number of replacement PDUs provided by the RLC layer to the MAC layer is equal to the number of PDUs required by the MAC layer from the RLC layer. The Radio Link Control (RLC) layer and the Medium Access Control (MAC) layer. Method for scheduling data between. The method of claim 4, wherein The unexpected data interruption is due to a discard timer, a reset operation, a suspend operation, a stop operation, or a re-stable operation, between the radio link control (RLC) layer and the media access control (MAC) layer. Method for data scheduling. The method of claim 4, wherein Wherein the at least one alternate PDU is a padded PDU. 2. The method of claim 1, wherein the alternate PDU is a padded PDU. 12. A wireless communications device comprising a processor executing a program for handling unexpected data interruption in data transmission scheduling between a radio link control (RLC) layer and a media access control (MAC) layer, The unexpected data interruption occurs after RLC entity information is provided to the MAC layer by the RLC layer, The program causes the RLC layer to submit an appropriate number of alternate protocol data units (PDUs) to the MAC layer in place of discarded or interrupted service data unit (SDU) data in response to a data request from the MAC layer. A wireless communication device, characterized in that. The method of claim 8, And said unexpected data interruption is due to a discard timer, a reset operation, a suspend operation, a stop operation, or a re-stablish operation. The method of claim 8, And the replacement PDUs are padded PDUs. 10. A wireless communications device comprising a processor executing a program for performing data scheduling between a radio link control (RLC) layer and a media access control (MAC) layer, The program, RLC entity information indicates that the RLC layer has Service Data Unit (SDU) data to be transmitted, causing the RLC layer to provide the RLC entity information to the MAC layer, Data interruption requires the RLC layer to discard or interrupt the transmission of the SDU data, causing the RLC layer to receive the data interrupt after providing the RLC entity information. Cause the MAC layer to request at least one protocol data unit (PDU) from the RLC layer in response to the RLC entity information, Cause the RLC layer to submit at least one replacement PDU to the MAC layer in response to the MAC request, and And wherein the at least one replacement PDU is submitted in place of the discarded or interrupted SDU data. The method of claim 11, wherein Wherein the number of replacement PDUs submitted by the RLC layer to the MAC layer is equal to the number of PDUs required by the RLC layer by the MAC layer. The method of claim 11, wherein Wherein said data interruption is due to a discard timer, a reset operation, a suspend operation, a stop operation, or a re-stablish operation. The method of claim 11, wherein And the at least one replacement PDU is a padding PDU. A method of handling unexpected data interruption in a wireless communication device, not due to a discard timer in data transmission scheduling between a radio link control (RLC) layer and a media access control (MAC) layer, the unexpected Data interruption occurs after RLC entity information is provided by the RLC layer to the MAC layer, A service data unit (SDU) in response to the unexpected data interrupt until the RLC layer submits the required number of protocol data units (PDUs) to the MAC layer in response to a MAC request initiated by the RLC entity information. ) Postponing the discarding or interrupting of the data. The method of claim 15, And said unexpected data interruption is due to a reset operation, a suspend operation, a stop operation, or a re-stablish operation. A method for data scheduling between a radio link control (RLC) layer and a medium access control (MAC) layer in a wireless communication device, the method comprising: The RLC layer providing RLC entity information to the MAC layer, wherein the RLC entity information indicates that the RLC layer has service data unit (SDU) data to be transmitted. Providing to the MAC layer; After providing the RLC entity information, the RLC layer receiving an unexpected data interrupt rather than due to a discard timer; After the unexpected data interruption, the MAC layer requesting at least one protocol data unit (PDU) from the RLC layer in response to the RLC entity information; The RLC layer providing at least one PDU to the MAC layer in response to the MAC request; And After submitting the at least one PDU to the MAC layer, and in response to the unexpected data interruption, the RLC layer discarding SDU data not submitted to the MAC layer. How to schedule data. The method of claim 17, And all remaining SDU data is discarded by the RLC layer in response to the unexpected data interruption after the at least one PDU has been submitted to the MAC layer. The method of claim 17, The unexpected data interruption may be due to a reset operation, a suspension operation, a stop operation, or a re-stablish operation. The method of claim 17, And the number of the at least one PDU submitted by the RLC layer to the MAC layer is equal to the number of PDUs requested by the MAC layer from the RLC layer.