KR20040067657A - Apparatus and method for requiring retransmission of radio link protocol data in mobile communication system - Google Patents

Abstract

PURPOSE: An apparatus and a method for requesting retransmission of radio link protocol data in a mobile communication system are provided to shorten a retransmission period by setting up the retransmission delay time according to the retransmission number and requesting the retransmission. CONSTITUTION: An apparatus for requesting retransmission of radio link protocol data in a mobile communication system includes a physical layer and a radio link protocol layer. The physical layer(212) is used for decoding an encoded frame received from a base station, requesting the retransmission of the encoded frame in case of a decoding failure, and transmitting the decoded frame and the retransmission number to the radio link protocol layer. The radio link protocol layer(211) is used for checking the frame received from the physical layer, storing the received frame into a queue, setting up the timer to request the retransmission, requesting the retransmission to the physical layer in case of a receiving failure of the frame, and transmitting the stored frame to an upper layer.

Description

Apparatus and method for requesting retransmission of radio link protocol data in a mobile communication system {APPARATUS AND METHOD FOR REQUIRING RETRANSMISSION OF RADIO LINK PROTOCOL DATA IN MOBILE COMMUNICATION SYSTEM}

The present invention relates to an apparatus and method for transmitting Radio Link Protocol (RLP) data in a mobile communication system, and more particularly, to an apparatus and method for retransmitting radio link protocol data.

In general, a mobile communication system is based on a voice service and has additionally provided a data service. However, as user demand for data services increases, a system for high-speed data services is developed one after another, and a 1x EV-DO system that provides only high-speed data services and a 1x EV_DV system that can provide voice services and multiple high-speed data services. This has come to appear. This 1x EV-DV system has been adopted in the code division multiple access (CDMA) method. We then look at the 1x EV-DV discussed in the CDMA 2000 standard agreement.

Currently, 1x EV-DV has been confirmed as Release C standard of the CDMA2000 standard, and a new data transmission method using a forward packet data channel (hereinafter referred to as "F-PDCH") has been added to 1x EV-DV. The F-PDCH differs in some respects from the Forward Supplemental Channel (hereinafter referred to as "F-SCH"), which is used by using a high speed data service. Among these, the F-PDCH uses a four-channel hybrid ARQ scheme, which can change the transmission order of RLP packets. In addition, the transmission delay between RLPs is much larger by retransmission. The proposed RLP transmission method transmits data through a channel close to a circuit type such as a forward basic channel (F-FCH), a forward dedicated channel (F-DCCH), or an F-SCH. It is designed for. Therefore, if the RLP transmission method is applied to the data transmission through the F-PDCH as it is, a significant performance degradation is brought.

In order to improve this, much research has been made on RLP transmission method suitable for transmitting data through F-PDCH. Next, the data transmission method using the F-PDCH in the 1x EV-DV system will be described.

First, the characteristics of data transmission using the F-PDCH will be described. The F-PDCH is shared and used in a time division multiplexing (TDM) scheme between mobile terminals. In addition, the base station receives a channel quality (CQ) information of the forward channel received by the mobile station to determine the transmission time, transmission rate, packet size, number of transmission slots and the like to the F-PDCH. In addition, techniques such as a code division multiplexing (CDM) method that can be simultaneously transmitted to two mobile terminals are applied. Here, an example of simple transmission is described in order to point out only the problem addressed by the present invention.

1 is a timing diagram when data transmission is performed through four ARQ channels through an F-PDCH. Hereinafter, a case in which data transmission is performed through four ARQ channels through the F-PDCH will be described with reference to FIG. 1. In addition, in the description of FIG. 1, it is assumed that an encoder packet (EP) is transmitted to only one mobile terminal during one slot without considering CDM. In case four ARQ channels are allocated to one mobile terminal, It is assumed to be described. It is also assumed that one RLP frame is made of one EP.

In the case of the above-described configuration, the BS PHY Layer 110 of the base station transmits an encoder packet to be transmitted to the mobile station through air. Then it is delivered to the physical layer (MS PHY Layer) 120 of the mobile terminal. After the base station transmits a specific encoder packet, the base station does not transmit data using the corresponding channel that transmitted the encoder packet until the acknowledgment (hereinafter, referred to as 'ACK') is received from the mobile station. However, if another channel exists in the mobile station, the next data is transmitted to the other channel.

This will be described with reference to FIG. 1. The base station as it is assigned a mobile terminal and a four ARQ channels, can send the data of the four encoder packets to each channel. That is, in FIG. 1, A1 denotes a first ARQ channel, A2 denotes a second ARQ channel, A3 denotes a third and A4 denotes a fourth ARQ channel. Since each ARQ channel is TDM, data is sequentially transmitted in the order of A1, A2, A3, and A4. In addition, in FIG. 1, in the part indicated by (y, z) of each channel, y means a sequence number of the encoder packet to be transmitted, and z is a value indicating 0 as an initial transmission and the number of retransmissions from 1 thereafter. Becomes

As shown in FIG. 1, the physical layer 110 of the base station transmits encoder packets having the order of 1, 2, 3, and 4 through four ARQ channels. Then, the physical layer 120 of the mobile terminal receives it, performs decoding, and checks whether there is an error. If an error occurs as a result of the check, the mobile station transmits a NACK signal to the base station, and if the error is received normally and transmits the ACK signal to the base station. Accordingly, the base station receiving the ACK signal initially transmits the next encoder packet through the corresponding ARQ channel. When receiving the NACK signal, the base station retransmits the encoder packet transmitted on the corresponding ARQ channel that received the NACK signal. In this case, a time point at which retransmission is performed is not made at a predetermined reference time point, and is determined differently according to scheduling of the base station.

Therefore, the physical layer 120 of the mobile station normally receives the encoder packets sequentially received, i.e., if there is no error as a result of decoding, the mobile layer physical layer 120 transmits them to the MS RLP layer 130 of the mobile station. do. Accordingly, the transmission delay time required for the encoder packet transmitted from the physical layer 110 of the base station to be delivered to the radio link protocol layer 130 of the mobile station is not constant. That is, when decoding fails continuously in the physical layer of the mobile terminal, the time transmitted to the radio link protocol layer 130 of the mobile terminal is gradually delayed. This example will be described with reference to FIG. 1, where an encoder packet transmitted through a second ARQ channel is successfully decoded in an initial transmission. Therefore, the time required for the transmission from the physical layer 110 of the base station to the radio link protocol layer of the mobile terminal takes time as shown in FIG. 1. However, in case of the encoder packet transmitted through the first ARQ channel, decoding was successful when retransmission was performed once. Therefore, there is a significant difference between the delay of the transmission time transmitted through the first ARQ channel and the second ARQ channel.

Therefore, the base station transmits encoder packets 1, 2, 3,. Although the transmission is performed in the order of, the reception is actually performed in a different order from the base station. That is, when transmitted as shown in FIG. 1, the sequence of encoder packets received by the radio link protocol layer 130 of the mobile terminal is made in the order of 2, 1, 6, 4, 3. As described above, the transmission is performed because the base station transmits an encoder packet of the next sequence through the ARQ channel that has been successfully transmitted, and the encoder packet that failed to transmit is retransmitted to the corresponding ARQ channel. Therefore, in the 1x EV-DV system, the reception order of encoder packets received by the mobile station may be different from the order of actual transmission. In addition, a large difference in transmission delay time of the encoder packet may occur.

Radio Link Protocol (RLP) is a protocol based on the transmission of NACK signals and is designed for IS-2000. Accordingly, as described above, when the transmission delay time difference of the encoder packet is large and the transmission order is changed, the following problem may occur.

First, if the radio link protocol transmission method is used in the 1x EV-DV system as it is, it may cause performance degradation due to data delay. This is because the radio link protocol transmission method is based on the transmission of the NACK signal as described above. That is, since the 1x EV-DV system adopts a hybrid automatic retransmission (HARQ) scheme, there is a problem that the retransmission delay time is large due to retransmission in the physical layer.

Second, the 1x EV-DV system uses four ARQ channels. Therefore, as described above, the order of encoder packets received may be different from the order of transmission. If the received order is different from the transmitted order, the radio link protocol method automatically transmits a NACK signal requesting retransmission. However, since the 1x EV-DV system is configured to request retransmission in the physical layer, the retransmission may be already required in the physical layer 120 of the mobile terminal or may have already been retransmitted in the physical layer 110 of the base station. have. Nevertheless, when the radio link protocol requires retransmission again, waste of radio resources occurs to request retransmission, and the base station may perform redundant retransmission. Even in this case, waste of radio resources occurs. Such a phenomenon may cause a problem that the performance of the entire 1x EV-DV system is degraded.

In addition, if the problem is to be solved by changing the IR (Increase Redundancy) layer, the complexity of the IR layer occurs. In addition, if the IR layer is changed in a direction that does not increase the complexity of the IR layer, there is a problem in that the performance improvement of the system is insufficient.

Accordingly, an object of the present invention is to provide an apparatus and method for increasing transmission efficiency in transmitting radio link protocol data in a mobile communication system.

It is still another object of the present invention to provide an apparatus and method for transmitting a signal requiring retransmission of data of a lost encoder packet of a physical layer in a radio link protocol layer of a 1x EV-DV system.

Another object of the present invention is to provide an apparatus and method for preventing unnecessary retransmission when transmitting radio link protocol data in a mobile communication system.

Another object of the present invention is to provide an apparatus and method for reducing the complexity of the system when transmitting radio link protocol data in a mobile communication system.

Another object of the present invention is to provide an apparatus and method for reducing a propagation delay of data received in a radio link protocol layer to a higher layer in a mobile communication system.

An apparatus of the present invention for achieving the above objects, as a mobile terminal device for a request for retransmission of radio link protocol data in a mobile communication system having two or more automatic retransmission channels, decoding and decoding an encoded frame received from a base station; In case of failure, the terminal requests retransmission up to a preset number of times, and transmits the retransmission count value to the radio link protocol layer along with the frame which has been successfully decoded, and information for setting the retransmission timer during the initialization of the radio link protocol layer when setting up a call. Receive and store, and check the sequence number when receiving the frame from the physical layer to inspect the unreceived frame, and if there is an unreceived frame, temporarily store the received frame in the queue, and the retransmission timer information and the Resend count value Set the timer to transmit the retransmission request signal by using this function.If the timeout of the retransmission timer occurs, request the retransmission.When the frame is received, the timer checks whether it can be delivered to the upper layer and delivers it to the upper layer. And a radio link protocol layer that reads possible frames from the queue and delivers them to the upper layer, and temporarily stores the queue in the queue if the upper frame is impossible to transmit.

The method of the present invention for achieving the above objects, the physical layer for transmitting the frame and the number of retransmission value received from the base station to the radio link protocol layer, and the radio link protocol for detecting the unreceived frame and requesting retransmission thereof A method for requesting retransmission of a frame in a radio link protocol layer of the mobile terminal in a mobile communication system performing data communication through a mobile terminal including a layer and two or more automatic retransmission channels, wherein a timer setting is performed when a frame is received from the physical layer. Checking whether there is a required non-received frame; and if there is an unreceived frame that requires the timer setting as a result of the check, information for setting a retransmission timer and the number of times of retransmission for the unreceived frame requiring the timer setting are used. So Setting a retransmission timer for a received frame and temporarily storing the received frame in a queue; and if the retransmission of the unreceived frame is not performed until a timeout of the timer occurs, a radio link protocol layer of the base station The process includes requesting retransmission.

1 is a timing diagram when data transmission is performed through four ARQ channels through an F-PDCH.

2 is a signal flow diagram illustrating a hierarchical flow of data and signal signals in a base station and a mobile terminal according to an embodiment of the present invention;

3 is a control flowchart when receiving data in an RLP layer of a mobile terminal according to an embodiment of the present invention;

4 is a diagram illustrating a queue for temporarily storing a frame received at an RLP layer and a timer for an unreceived frame according to an embodiment of the present invention;

5 is a signal flow diagram for synchronizing a retransmission timer parameter according to an embodiment of the present invention;

6 is a timing diagram illustrating a process of making a request for retransmission of an RLP layer according to an embodiment of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. First of all, in adding reference numerals to the components of each drawing, it should be noted that the same reference numerals have the same reference numerals as much as possible even if displayed on different drawings.

In addition, in the following description, many specific matters such as specific messages and the like appear, which are provided to help a more general understanding of the present invention, and the present invention may be practiced without these specific matters. It is self-evident to those who have knowledge. In the following description of the present invention, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

The method proposed in the present invention uses a method of transmitting a retransmission count (subpacket transmission count) of an EP that has been successfully received by the IR layer to the RLP layer and dynamically setting a waiting time until the NLP is transmitted from the RLP layer.

2 is a signal flow diagram illustrating a hierarchical flow of data and signal signals in a base station and a mobile terminal according to an exemplary embodiment of the present invention. Hereinafter, the flow of data and signals in each layer of the base station and the flow of data and signals in each layer of the mobile terminal will be described in detail with reference to FIG. 2.

First, the hierarchical structures of the mobile terminal 210 and the base station 220 illustrated in FIG. 2 will be described. In addition, FIG. 2 illustrates only the hierarchical structure of the mobile terminal 210 and the base station 220 necessary for the present invention, and the following description will be provided only with the illustrated hierarchical layer except inevitable cases.

The mobile terminal 210 includes a radio link protocol layer (RLP layer) (hereinafter referred to as "RLP layer") 211 and a physical layer (PHY Layer) 212. The physical layer 212 performs a process for transferring the frame data received from the RLP layer 211 to the Air state in the physical layer when transmitting the frame data to the base station 220. In addition, the physical layer 212 decodes the received frame upon reception of the frame data and transfers it to the RLP layer 211. The base station 220 also includes an RLP layer 221 and a physical layer 222, and the operations to be performed are the same. In addition, as shown in FIG. 2, a case in which frame data is transmitted from the base station 220 to the mobile station 210, that is, a case in which retransmission is performed according to forward data transmission will be described.

When data to be transmitted is generated, the RLP layer 221 of the base station 220 configures radio link protocol frame data (RLP frame data), and transmits it to the physical layer 222. Then, the physical layer 222 encodes the frame data received from the RLP layer 221 as described above, and transfers it to the mobile terminal 210 through the established channel. At this time, in the case of the 1x EV-DV system, up to four ARQ channels that can be set from the base station 220 to the mobile terminal 210 are possible. Accordingly, the base station 220 may transmit data to the mobile station 210 through up to four ARQ channels. As such, when data is transmitted from the physical layer 222 of the base station 220 to the physical layer 212 of the mobile terminal 210, the physical layer 212 of the mobile terminal 210 decodes the received encoded frame. When the data of the frame received as a result of decoding is normally received, that is, received without an error, the physical layer 212 transfers it to the RLP layer 211 which is a higher layer. The ACK signal, which is a reception good signal, is transmitted to the physical layer 222 of the base station 220. In addition, according to the present invention, the physical layer 212 of the mobile terminal 210 transmits the number of retransmissions while transferring the decoded data to the RLP layer 211. If retransmission is not performed, the retransmission count value may be set to "0" and transmitted, or the retransmission count value may not be transmitted. As such, the interface between the physical layer and the RLP layer should be modified to transfer the retransmission count value from the physical layer 212 to the RLP layer 211. An interface parameter between the physical layer and the RLP layer modified according to the present invention may be illustrated as shown in Table 1 below.

Primitive Type Primitive Parameters Primitive Used In Response PHY-DecodedFPDCH acid, ep, sys_time, num_slots, num_retx Mobile station

Table 1 is the same as the content adopted in the current 1x EV-DV standard except for the parameter of "num_retx" according to the present invention. Then, each parameter and its description are as follows as adopted in the 1x EV-DV standard.

"Indicates that an encoder packet has been decoded (successfully or unsuccessfully) on the FPDCH.

acid is set to the ARQ Channel Identifier for the decoded encoder packet;

ep is set to the decdode encoder packtet or is set to NULL if the encoder packet was not successfully decoded;

sys_time is set to the system time (in 1.25ms units) for the first slot of the successfully or unsuccessfully decoded encoder packet.

The parameter of "num_retx" which is a parameter according to the present invention among the parameters shown in Table 1 may be defined as follows.

"num_slots is set to the number of retransmissions which can be obtained by counting the number of decoding."

That is, in the present invention, when the decoded frame received without error in the physical layer 212 of the mobile terminal 210 is transmitted to the RLP layer 211, the retransmission count value is transmitted using the parameter value.

A method different from the above method may be used to detect the number of retransmissions of a frame received at the RLP layer 211 of the mobile station 210. In this case, the number of frames transmitted from the RLP layer 211 to the physical layer 212 is counted. The same effect can be obtained in the present invention by using any of the two methods described above.

On the other hand, if the received frame data is abnormally received, that is, if there is an error in the received frame data, the physical layer 212 does not transfer it to the upper layer RLP layer 211, and immediately of the base station 220 The physical layer 222 transmits a "NAK" signal, which is a reception failure signal. In the physical layers, data transmission is based on ACK / NAK, so that the ACK / NAK signal is immediately transmitted according to whether the received signal is good or bad. Therefore, if an error exists in a frame received as a result of decoding in the physical layer, the physical layer 212 transmits a retransmission request signal (PHY Layer retransmission request) of the physical layer to the physical layer 222 of the base station 220. Through this, the physical layer 222 of the base station retransmits the transmitted frame.

Next, an operation performed by the RLP layer 211 of the mobile terminal 210 will be described. When the decoding frame is received, the RLP layer 211 of the mobile station checks the sequence (SEQ) number of the received decoding frame. If the sequence number of the decoding frame received from the physical layer 212 is the same as the order of the transmitted frame, it is transmitted to the upper layer. This will be described in more detail as follows.

It is assumed that the base station 220 sequentially transmits frame data in the order of sequence numbers 1, 2, 3, and 4. Then, the RLP layer 211 of the mobile station 210 transfers the sequence number of the frame, which has been successfully decoded from the physical layer 212, to 1, 2, 3, 4 to the upper layer. However, there may occur a case where a specific number of sequence numbers of the received frame is not received. For example, if only two or four received sequence numbers are received, the RLP layer 211 of the mobile station 210 may confirm that there are at least two frames that have failed decoding in the physical layer 212. That is, it can be seen that an error has occurred in the frames of sequence numbers 1 and 3. Therefore, in this case, the RLP layer 211 stores the received frame in a predetermined queue and delivers it to a higher layer when a previous frame is received. That is, the RLP layer 211 transmits the frame of sequence number 1, which is the previous frame necessary to transmit the frame of sequence number 2, to the upper layer when the frame of sequence number 1 is received. Other frames are delivered to the higher layer in the same way.

However, when the RLP layer 211 of the mobile terminal 210 immediately requests retransmission as in the related art, the following problem occurs. In 1x EV-DV, the number of retransmissions between physical layers is predetermined. In addition, in 1x EV-DV, one mobile terminal may have up to four ARQ channels. In this case, the base station 220 continuously transmits four frames to the mobile station 210. However, when the frames successfully received by the mobile station 210 do not successfully transmit all four, the physical layer 212 of the mobile station 210 immediately requests retransmission to the base station 220. That is, a state in which retransmission is requested for the corresponding frame in which a transmission error occurs. Nevertheless, if the RLP layer 211 of the mobile station 210 directly requests retransmission through the physical layer 212 to the base station 220, duplicate transmission is performed for the same frame, resulting in waste of channel resources or Problems can occur with frame data transmission.

Therefore, in 1x EV-DV, a frame retransmitted in the physical layer 212 needs to be considered. Accordingly, the RLP layer 211 may request retransmission after waiting as many times as the number of retransmissions performed in the physical layer 212 to consider the frame retransmitted in the physical layer. However, this method is not an optimal method. This is because a frame having a sequence number 2 and a sequence number 4 may not be a successful initial transmission, but may be a frame that has been successfully decoded through one or two or more retransmissions. In this case, the RLP layer 211 of the mobile terminal 210 actually transmits a retransmission signal from the physical layer 212 to the base station 220 and waits for retransmission of the frame data for a longer time than the time for retransmission of the corresponding frame. must do it.

Therefore, in order to reduce the time, the present invention modifies the interface between the RLP layer and the physical layer to transmit a retransmission count value from the physical layer 212 to the RLP layer 211 for a frame that has been successfully transmitted. Accordingly, the RLP layer 211 may set the retransmission waiting timer by subtracting the time according to the retransmission count value of the currently received frame from the time according to the preset retransmission count. Hereinafter, the retransmission waiting timer is referred to as a "timer". Through this modified interface, the RLP layer 211 can wait for data retransmission more efficiently.

3 is a control flowchart when receiving data in the RLP layer of a mobile terminal according to an embodiment of the present invention. Hereinafter, referring to FIG. 3, a retransmission request when receiving data in an RLP layer of a mobile terminal according to the present invention, a timer management method according to the present invention, and a method of delivering a successful frame to a higher level will be described in detail. In addition, FIG. 3 is a control process at the time of data reception according to the present invention and is not shown with respect to operations not related to the present invention. Therefore, operations of other RLP layers not related to the present invention will not be described in detail.

The RLP layer 211 maintains the standby state in step 300. Here, the standby state refers to a state in which an event requiring a specific operation is waited for to occur. The RLP layer 211 performs step 300 and proceeds to step 302 to check whether a timeout occurs. If a timeout occurs as a result of the inspection, the flow proceeds to step 304; otherwise, the flow proceeds to step 306. In step 304, the RLP layer 211 requests retransmission in the RLP layer. That is, the retransmission request signal is finally transmitted from the RLP layer 211 shown in FIG. 2 to the RLP layer 221 of the base station 220 through the physical layer 212. Since the timeout is a part related to retransmission, it will be described in more detail later.

In step 306, the RLP layer 211 checks whether a frame has been received. If the check result frame is received, the process proceeds to step 308, otherwise, the standby state of step 300 is maintained. The RLP layer 211 checks whether the frame on which the timer is driven is received when the check result frame of step 306 is received and proceeds to step 308. The timer-driven frame refers to a frame set for a retransmission request of the RLP layer 211 with respect to a frame in which the RLP layer 211 knows that transmission has failed. This will be described in more detail with reference to FIG. 4.

4 is a diagram illustrating a queue for temporarily storing a frame received at an RLP layer and a timer for an unreceived frame according to a preferred embodiment of the present invention. The sequence number 2, the sequence number 4, and the sequence number N of the hatched area in the queue 400 of FIG. 4 illustrate a state in which a frame is received and temporarily stored. Also, sequence numbers 1 and 3, which are not hatched, show a state in which no frame is received. That is, when a frame of sequence number 2 is received while the frame of sequence number 1 is not received, the RLP layer 211 temporarily stores the frame of sequence number 2 in the queue 400, and stores the frame of sequence number 1 in the sequence number 1. Set a timer for In FIG. 4, different timers Timer 1, Timer 2,..., Timer m are shown for each unreceived frame. That is, the first timer (Timer 1) for the frame of the sequence number 1, the second timer (Timer 2) for the sequence number 3 and the like are shown. The first timer (Timer 1) and the second timer (Timer 2) are different timers. The time for setting the timer will be described in more detail in step 322.

The inspection of step 308 is a process of checking whether a frame having a timer set as shown in FIG. 4, that is, an unreceived frame not previously stored in the queue of the RLP layer 211 is newly received. If the unreceived frame is received, the RLP layer 211 proceeds to step 310, otherwise proceeds to step 316. The process proceeds from step 308 to step 316, that is, a case in which a frame in which a timer is not driven is received is described first. If the RLP layer 211 proceeds to step 316, the RLP layer 211 checks whether there is an unreceived frame by checking a sequence number. That is, it is checked whether the sequence number of the currently received frame is 4, and any frame of sequence numbers 1, 2, and 3, which are previous frames, is not received. If it is assumed that the frame is received as shown in FIG. 4 and only the sequence number 4 is considered, when the sequence number 4 is received, the frame of the sequence number 2 is already received. Accordingly, it can be seen that the frames not received so far have not received the frames of sequence number 1 and sequence number 3.

Therefore, the RLP layer 211 proceeds to step 318 to check whether a new unreceived frame exists. The reason for the inspection of this new unreceived frame is that if sequence number 2 is received before the sequence number 4 from the currently received frame, the first timer for the sequence number 1 is already set. Therefore, only the timer for sequence number 3 needs to be set. However, if sequence number 2 is received by retransmission after the frame of sequence number 4 is received, sequence numbers 1, 2, and 3 are all unreceived frames when the frame of sequence number 4 is received. In this case, therefore, timers should be set for sequence numbers 1, 2, and 3.

Next, a case in which the new unreceived frame exists in step 318 and the process proceeds to step 322 will be described. In step 322, the RLP layer 211 sets a timer for new unreceived frames. At this time, as described above, the timer is set only when there is a new unreceived frame. The timer value can be determined by various methods. Detailed description thereof will be described in detail later with reference to FIG. 5.

As illustrated above, if the frame of sequence number 2 is received and the frame of sequence number 4 is received thereafter, the timer is already in operation for sequence number 1. Therefore, the timer is not set newly when it is not received but is not a new not received frame. Since the sequence number 3 is a new unreceived frame, a timer for the sequence number 3 is set. On the contrary, even when sequence number 4 is received first and frames of sequence number 2 are received later, a timer is not newly set for the frame of sequence number 1 when the frame of sequence number 2 is received. This is because the timer for the frame of sequence number 1 is already set.

That is, the RLP layer 211 sets a timer for a new unreceived frame in step 322 and then proceeds to step 324 to store the received frame in the queue 400. This is because the sequence numbers of the frames must be sequentially aligned in the upper layer.

On the other hand, if the new unreceived frame does not exist as a result of the check in step 318, the flow proceeds to step 320 and transfers the currently received frame to the upper level. If the frame is not received, the process proceeds from step 308 to 310, because the currently received frame cannot be an unreceived frame.

Then, if the process proceeds from step 308 to 310, that is, if the currently received frame is an unreceived frame in which the timer is driven, the process proceeds to step 310 to check whether there is a frame that can be delivered to the upper level due to the received frame. do. This will be described with reference to FIG. 4 again. When the frames of the sequence number 2 and the sequence number 4 are received, when the sequence number of the received frame is 1, the frames of the sequence number 1 and the sequence number 2 may be transferred upward. However, if the frame of the sequence number 3 is received while the frames of the sequence number 2 and the sequence number 4 are received, the frame of the sequence number 1 is not received and thus cannot be transferred to a higher level. That is, step 310 is a process of checking whether there are frames in a state that can be transmitted upward by a series of consecutive sequence numbers among previously received sequence numbers due to the currently received frame.

If the frame that can be transmitted to the upper level as a result of the check in step 310 is satisfied, the RLP layer 211 proceeds to step 312. This will be described with reference to FIG. 4 again, where a frame of sequence number 1 is received while the sequence number 2 and sequence number 4 are received. In this case, the RLP layer 211 transfers a frame that can be delivered to a higher layer due to the received frame among the frames received in step 312 and the frames stored in the queue 400 to the upper layer. In addition, the timer for the frame of sequence number 1 that was in operation is removed. That is, since the timer for the frame of sequence number 1 is no longer needed, the RLP layer 211 removes it and proceeds to step 300.

On the contrary, when proceeding from step 310 to step 314, that is, when the frame of sequence number 3 is received while the frames of sequence number 2 and sequence number 4 are received, the RLP layer 211 determines that the received sequence number 3 After storing the frame in the queue 400, the process proceeds to step 300.

Finally, when the timer is set as described above, a case in which the frame of the sequence number is not received until the timer times out will be described. If the check result timeout occurs in step 302 as described above, the RLP layer 211 proceeds to step 304 and requests retransmission for the corresponding sequence number. In this case, the retransmission request is not a retransmission request in the physical layer but a retransmission request between RLP layers, which is a retransmission request indicated by a dotted line of FIG. 2 as described above.

5 is a signal flow diagram for synchronizing a retransmission timer parameter according to a preferred embodiment of the present invention. Hereinafter, the synchronization of the retransmission timer parameter and the timer setting method in the RLP layer according to the timer parameter will be described in detail with reference to FIG. 5.

When the mobile terminal 210 establishes a data call in order to receive a high speed data service, the mobile terminal 210 performs an initialization process of the RLP in step 510. Since the previous step of the RLP initialization process in FIG. 5 is unrelated to the present invention, description thereof is omitted and is not shown in FIG. 5. In the RLP initialization process of step 510, the mobile station 210 and the base station 220 are initialized by matching RLP parameter values while exchanging RLP BLOBs. At this time, the base station 220 includes the information on DELAY_DETECTION_WINDOW in the RLP BLOB and transmits it to the mobile terminal 210. Therefore, the mobile terminal 210 receives the DELAY_DETECTION_WINDOW information and stores it therein. In addition, the RLP BLOB may be transmitted not only at call setup but also when a call is established and a service is in progress.

In the present invention, the delay detection window DELAY_DETECTION_WINDOW may be used in three cases. First, a method of using one delay detection window information included in an RLP BLOB. Secondly, the base station 220 provides the mobile terminal 210 with a scaling factor in addition to one delay detection window information included in the RLP BLOB. Third, different delay detection window values are set in the RLP BLOB according to the number of retransmissions.

Next, the first method will be described. The first method is to use one delay detection window. The delay detection window value is differently calculated using the number of retransmissions. If configured in this way, modifications are required to the currently provided RLP BLOB messages. When the RLP BLOB message changed as described above is shown in a table, it may be shown as shown in Table 2 below.

Field Length (bits) RLP_BLOB_TYPE 3 RLP_VERSION 3 … … DELAY_DETECTION_WINDOW 0 or 8

The delay detection window field is added as shown in the bottom of Table 2. As described above, the delay detection window value in the RLP BLOB message is a value used when initializing an RLP and setting a call as described above. The value is a value indicating the delay time. The delay detection window value may transfer the time from the initial transmission to the last transmission time as one value. When the message is received, the mobile station stores it. When an unreceived frame is generated, a timer setting performed in the RLP layer 211 of the mobile station 210 is performed. At this time, a timer is set using the value, and the timer value may be set as in Equation 1 below.

In Equation 1, 1 located in the denominator means initial transmission, and num_retx means retransmission number. Therefore, the value of the denominator is the total number of transmissions including the initial transmission when assuming that there is no error in the control channel.

Next, a method of providing a scaling factor in addition to the delay detection window information included in the RLP BLOB to the mobile station 210 by the base station 220 as a second method will be described.

The second method is a method of dynamically setting a delay detection window value in which the base station transmits the scaling value to the terminal in advance. To use the second method, the RLP BLOB message should contain more information than Table 2 above. That is, the base station 220 should inform the mobile terminal 210 of more information. Then, when the RLP BLOB message according to the second embodiment is illustrated as a table, it may be configured as shown in Table 3 below.

Field Length (bits) RLP_BLOB_TYPE 3 RLP_VERSION 3 … … DELAY_DETECTION_WINDOW 0 or 8 NUM_SCALING_FACTORS 0 or 3 NUM_SCALING_FACTORS occurrences of the following: (RETX_Y means the number of retransmission) RETX_Y 0 or 5

In Table 3, the scaling value itself may mean an integer value, or may be used as an index indicating another value. In addition, the value represented by 5 bits is only an embodiment and does not mean having a number of bits. In addition, the second field from the bottom of Table 3 is not an actual field, and is inserted to indicate that the bottom field is included as many as the number indicated in the NUM_SCALING_FACTORS field. As shown in Table 3, the scaling value is transmitted from the base station 220 to the mobile station 210 so that the retransmission timer in the RLP layer 211 of the mobile station 210 is set differently from the first method. Then, according to this method, the timer value can be calculated and calculated as shown in Equation 2 below.

The calculation of Equation 2 is performed as follows. First, the mobile station 210 previously stores a scaling value according to the number of retransmissions included in the RLP BLOB message received from the base station 220. In addition, the corresponding scaling value of the RLP BLOB message is found from the retransmission count value of the received frame or the retransmission count value of the unreceived frame received from the physical layer 212 of the mobile station 210. The timer is set using the delay detection window value included in the RLP BLOB message. Through this, the timer value can be set variably according to the number of retransmissions of the frames that are not actually received in the RLP layer.

Finally, we explain how to set different delay detection window values according to the number of retransmissions in the RLP BLOB. As described above, when the number of retransmissions is included in the RLP BLOB message, other fields should be added to the <Table 2>. If this is shown in a table it can be shown as shown in Table 4.

Field Length (bits) RLP_BLOB_TYPE 3 RLP_VERSION 3 … … NUM_DELAY_DETECTION 0 or 3 NUM_DELAY_DETECTION occurrences of the following: (Y means the number of retransmission) DELAY_DETECTION_WINDOW (Y) 0 or 8

The second field below <Table 4> is not an actual field, but merely a value representing the value of NUM_DELAY_DETECTION, that is, the number including DELAY_DETECTION_WINDOW (Y) of the last field. For example, if the value of NUM_DELAY_DETECTION is 2, two DELAY_DETECTION_WINDOW (Y) fields are included. In this case, DELAY_DETECTION_WINDOW (1) and DELAY_DETECTION_WINDOW (2) are included.

As shown in Table 4, the fixed value according to the number of times of retransmission may be transmitted to the RLP BLOB message in advance. When the RLP BLOB message is changed as described above, the mobile terminal 210 may store it and set a retransmission timer value as shown in Equation 3 below when an unreceived frame occurs.

In Equation 3, the number of retransmissions may be used through a value received from the physical layer 212 of the mobile terminal 210.

As described above, the initialization of the RLP for setting the timer is initially performed when the call is established between the mobile station 210 and the base station 220. Of course, as described above, even if the call is set up, the service can be reset. When the RLP initialization process is completed, the mobile station 210 and the base station 220 proceed to step 520 to perform PPP initialization for data service. When the PPP initialization is completed, the data service is performed between the base station 220 and the mobile terminal 210 in step 530.

6 is a timing diagram illustrating a process of making a request for retransmission of an RLP layer according to an embodiment of the present invention. Hereinafter, a retransmission timer setting for requesting retransmission of an unreceived frame in the RLP layer will be described in detail with reference to FIG. 6. In addition, FIG. 6 illustrates a case where four ARQ channels are allocated between the base station 220 and the mobile station 210. Transmission of ACK / NAK signals between physical layers is not shown. In addition, in FIG. 6, a portion indicated by a dotted line becomes a portion that fails to transmit, and a portion indicated by a solid line indicates a portion that transmits successfully.

The RLP layer 221 of the base station 220 sequentially transmits frames of sequence numbers 1, 2, 3, and 4 to be transmitted to the physical layer 222 through four ARQ channels. Among the (x, y) shown in the physical layer 222 of the base station 220, x is a sequence number of a frame to be transmitted, y is 0 for initial transmission, and then 1 is a retransmission count value. As such, the frames transmitted from the RLP layer 221 of the base station 220 to the physical layer 222 are transferred to the physical layer 212 of the mobile terminal 210. Then, the physical layer 212 performs decoding, and if the decoding fails, the physical layer 212 transmits a bad signal NAK to request retransmission in the physical layer. Then, the base station 220 retransmits the frame of the ARQ channel required to be retransmitted according to the scheduling. When all the frames transmitted by the base station 220 fail in initial transmission as shown in FIG. 6 and the frames received through the second ARQ channel in retransmission succeed, the physical layer 212 of the mobile terminal 210 is transmitted. ) Transmits the successful decoding frame to the RLP layer 211. At this time, the physical layer 212 transfers the retransmission count value together with the RLP layer 211, which transmits the frame that has been successfully decoded according to the present invention. Then, in step 610, the RLP layer 211 may recognize that the frame of sequence number 1 has failed to be received and has been retransmitted once. Accordingly, the RLP layer 211 sets a timer for transmitting a retransmission request signal for the sequence number 1 in step 610. The received frame of the sequence number 2 is stored in the queue 400. At this time, the timer is set according to the same method as in <Equation 1> to <Equation 3>. These timer settings are set differently depending on the format of the RLP BLOB message. In addition, if the timer is set to only the delay detection window value as described above, there is a problem of waiting for a longer time as indicated by reference numeral 620. However, applying the present invention can shorten this time.

If the decoding succeeds in the frame of sequence number 4 in the physical layer 212 of the mobile terminal 210, the mobile station 210 transmits the decoding to the RLP layer 211 in step 630. In step 630, the RLP layer 211 stores the received frame of sequence number 4 in the queue 400 and sets a timer for retransmission request for the frame of sequence number 3. At this time, the timer is set in the same manner as the method performed in step 610.

In addition, when the data transmission is successful through a specific ARQ channel, the base station 220 transmits the following frames through the ARQ channel in which the data transmission is successful. When the timeout of the set timer is detected while the transmission is performed in this manner, a retransmission of the corresponding frame is requested. That is, the timeout occurs in step 640 for the frame of sequence number 1. When the timeout occurs as described above, the RLP layer 211 transmits an RLP layer retransmission request to the base station 220 through the physical layer 212. The physical layer 222 of the base station 220 then delivers it to the RLP layer 221. Accordingly, when the RLP layer 221 of the base station 220 receives the retransmission request, the RLP layer 221 performs retransmission for the corresponding frame in step 650. That is, the frame is transmitted to the physical layer 222 so that retransmission is performed.

As described above, by setting the retransmission delay time according to the number of retransmissions in the RLP layer and requesting the retransmission, there is an advantage that the retransmission time can be shortened while avoiding redundant transmission of signals or data.

Claims (12)

A mobile terminal device for requesting retransmission of radio link protocol data in a mobile communication system having two or more automatic retransmission channels, A physical layer that decodes an encoded frame received from a base station, requests retransmission up to a preset number of times when the decoding fails, and transmits a retransmission count value to the radio link protocol layer together with the successfully decoded frame; Receive and store information for retransmission timer setting during the initialization of the radio link protocol layer when setting up a call, examine the unreceived frame by checking the sequence number when receiving a frame from the physical layer, and if the received frame exists Is stored in the queue temporarily, and sets a timer for transmitting a retransmission request signal using the retransmission timer information and the retransmission count value for an unreceived frame, and requests a retransmission when a timeout of the retransmission timer occurs. When the set frame is received, it checks whether it can be delivered to the upper layer and if it can be delivered to the upper layer, the radio link protocol layer reads the deliverable frame from the queue and delivers it to the upper layer. Characterized by including The device. The method of claim 1, The setting of the timer is characterized in that for setting the time as shown in Equation (4). In Equation 4, DELAY_DETECTION_WINDOW is information for setting the retransmission timer and is a predetermined time value considering the maximum number of transmissions. The denominator value is the total number of transmissions including the initial transmission when there is no error in the control channel. The method of claim 1, The setting of the timer is characterized in that for setting the time as shown in Equation (5). In Equation 5, DELAY_DETECTION_WINDOW is a predetermined time value considering the maximum number of transmissions as information for setting the retransmission timer, and a scaling value according to the number of retransmissions is also a value according to the number of retransmissions as information for setting the retransmission timer. The method of claim 1, wherein the radio link protocol layer, The apparatus, characterized in that for updating the information for setting the retransmission timer from the base station when the call is set to update the information for the retransmission timer setting. A mobile terminal comprising at least two automatic retransmission channels including a physical layer for transmitting a frame and a number of retransmission values received from a base station to a radio link protocol layer, and a radio link protocol layer for detecting an unreceived frame and requesting retransmission thereof. In the method of requesting retransmission of the frame in the radio link protocol layer of the mobile terminal in a mobile communication system for performing data communication, Checking whether there is an unreceived frame requiring timer setting when receiving a frame from the physical layer; If there is an unreceived frame requiring the timer setting as a result of the check, a retransmission timer for the unreceived frame is set using the information for setting the retransmission timer and the number of retransmissions for the unreceived frame requiring the timer setting and the reception is performed. Storing the stored frames in a queue temporarily, Requesting retransmission to the radio link protocol layer of the base station if retransmission for the unreceived frame is not performed until a timeout of the timer occurs. The method of claim 5, wherein the information for setting the retransmission timer, And the information received and stored when the base station and the radio link protocol are initialized when a call is set up. The method of claim 6, And updating information received from the base station when the information for setting the retransmission timer is requested from the base station while the call is set. The method of claim 5, Checking whether all the previous frames including the received frame were successful when the frame data in which the timer is driven is received; And if the previous frame is all successful as a result of the check, transmitting successive frames having a later order than the received frame to a higher layer. The method of claim 8, And storing the received frame temporarily in the queue when all of the previous frames are unsuccessful. The method of claim 5, And transmitting the received frame to a higher layer when an unreceived frame does not exist when receiving a frame from the physical layer. The method of claim 5, The setting of the timer is characterized in that for setting the time as shown in Equation 6. In Equation 6, DELAY_DETECTION_WINDOW is information for setting the retransmission timer and is a predetermined time value in consideration of the maximum number of transmissions. The method of claim 5, The setting of the timer is characterized in that for setting the time as shown in Equation (7). In Equation 7, DELAY_DETECTION_WINDOW is a predetermined time value considering the maximum number of transmissions as information for setting the retransmission timer, and a scaling value according to the number of retransmissions is also a value according to the number of retransmissions as information for setting the retransmission timer.