KR100755269B1 - Method and apparatus for driving retransmission timer in mobile communication system using wireless link protocol - Google Patents

Abstract

The present invention relates to a method and apparatus for driving a timer for retransmitting radio link protocol frame data in a mobile communication system. In the radio link protocol (RLP) frame data processing method of a mobile communication system, RLP frame data is generated. If so, using the DRC (Data Rate Control) value transmitted by the mobile communication terminal to calculate the RLP retransmission timer operation time, and operating the RLP retransmission timer with the calculated timer operation time and transmits the RLP frame data Determining whether the RLP retransmission timer expires and removing the corresponding RLP frame data from the buffer when the RLP retransmission timer expires, and transmitting the RLP frame data to the receiving terminal in the mobile communication system according to the channel state. Dynamically setting the buffering timer run time Where a high rate, giving a shorter timer operation time where the low bit rate has the advantage to increase the efficiency RLP buffer by setting the timer operation time longer.

Description

METHOD AND APPARATUS FOR DRIVING RETRANSMISSION TIMER IN MOBILECOMMUNICATION SYSTEM USING RADIO LINK PROTOCOL}

1 is a block diagram for transmitting a retransmission request signal in a radio link protocol layer of a mobile communication system according to the present invention;

2 is a block diagram of an apparatus for transmitting radio link protocol data by dynamically operating a retransmission timer in a mobile communication system according to an exemplary embodiment of the present invention.

3 is a flow chart for transmitting radio link protocol data by dynamically operating a retransmission timer in a mobile communication system according to an embodiment of the present invention.

The present invention relates to a timer driving apparatus and method for retransmitting RLP frame data in a mobile communication system using a radio link protocol (hereinafter referred to as "RLP"), and in particular, to retransmission of RLP frame data in a mobile communication system. The timer operation time is set dynamically according to the wireless channel status. When the reception retransmission timer expires, the NAK requesting RLP frame retransmission is transmitted. When the transmission retransmission timer expires, the transmitted RLP frame data is transmitted from the transmission RLP buffer. An apparatus and method for removing the present invention.

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, systems for high-speed data services have been developed one after another, providing a CDMA 1x EV-DO (1x Evolution Data Only) system, which provides only high-speed data services, voice services, and multiple high-speed data services. A CDMA 1x EV_DV system has been introduced that can provide.

However, existing data services are services based on the Transmission Control Protocol (TCP) / Internet Protocol (IP) protocol for the wired network-based Internet, and it is unreasonable to apply these protocols to the wireless network as it is. In other words, when TCP was first created, it was made considering wired links. If the TCP used in the wireline is used in the wireless link without considering the characteristics of the wireless link, the TCP recognizes all the losses due to transmission errors as the congestion loss and performs the congestion control algorithm. In such a wireless environment, TCP operation is not only unnecessary operation when packet loss is caused by transmission error, but also causes significant performance degradation. The Automatic Repeat reQuest (ARQ) technique is a basic technique to improve the problem of TCP in such a radio link. Data is being recovered by retransmission.

For example, the RLP of the CDMA EV-DO Rev. 0 system basically uses Nak-based ARQ for packet retransmission. 'Nak-based' means that buffering should be done for packet retransmission for a sufficient time. That is, when the transmitting RLP transmits the frame data, when the transmitting side operates the timer and receives no Nak for a sufficient time, the receiving RLP reports that the receiving frame data has been normally received, and removes the transmitted RLP frame data from the transmitting RLP buffer. The receiving RLP receives the RLP frame data, and if there is an error, sends a NAK message to the transmitting terminal to request retransmission. The transmitting RLP retransmits the transmitted RLP frame data upon receiving Nak.

According to the current 3GPP2 C.S0024-0 cdma2000 High Rate Packet Data Air Interface Specification (C.S0024-0), it explicitly mentions the abort timer and flush timer in relation to RLP. In addition, the system defines that the following requirements must be met. "The RLP transmitter should allow sufficient time before deleting a packet transmitted for the first time." (3GPP2 C.S0024-0 specification). The abort timer refers to the time taken until the retransmission frame is received after transmitting the Nak in the receiving RLP, and the flush Timer indicates the time taken until the corresponding Nak is received after transmitting the RLP frame in the transmitting RLP. Say.

The RLP is basically a L2 layer protocol operating on a Nak basis. In other words, RLP is a CDMA-specific L2 protocol that minimizes retransmission in the upper layer to prevent performance degradation of the upper layer. Of course, the RLP can operate on the ACK basis, but since this may cause drawbacks that can increase the load on the radio section, it is desirable to operate on the ACK basis in applications requiring the general best effort characteristic. Not. However, because operating on a Nak basis does not know when to receive a Nak, the system has to keep the packet in the buffer for some time after the first transmission of the packet. Of course, the longer the predetermined time, the better the retransmission throughput for Nak requests, which may be advantageous in terms of throughput, but this has the problem that the system should store packets for that time.

Accordingly, there is a need for a method and apparatus for efficiently setting a timer operation time for RLP retransmission.

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

Another object of the present invention is to provide a method and apparatus for dynamically setting a timer operation time for retransmission in a radio link protocol layer of a 1x EV-DO system.

Another object of the present invention is to provide a method and apparatus for using a retransmission timer time for retransmission according to a wireless channel state in a radio link protocol layer of a 1x EV-DO system.

A method according to the present invention for achieving the above object, in the radio link protocol (RLP) frame data processing method of the mobile communication system, when the RLP frame data is generated, the DRC (transmission) transmitted by the mobile communication terminal ( Calculating an RLP retransmission timer operation time using a Data Rate Control) value, operating the RLP retransmission timer and transmitting the RLP frame data using the calculated timer operation time, and determining whether the RLP retransmission timer expires And removing the corresponding RLP frame data from the buffer when the RLP retransmission timer expires.

Another apparatus according to the present invention for achieving the above object, the radio link protocol (RLP) frame data processing of the mobile communication system, when the RLP frame data is generated, using the DRC (Data Rate Control) value A RLP retransmission timer for calculating an RLP retransmission timer operation time and operating an RLP retransmission timer with the calculated timer operation time, transmitting the RLP frame data through a communication unit, and determining whether the RLP retransmission timer expires and determining the RLP retransmission timer. And a controller for removing the corresponding RLP frame data from the buffer when it expires.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In describing the present invention, when 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.

Hereinafter, an apparatus and method for transmitting resource RLP frame data to a receiving terminal in a mobile communication system and dynamically setting a retransmission timer operation time according to a channel state will be described. The description below is based on the forward channel. An example of transmitting RLP frame data from a base station to a mobile communication terminal will be described as an example, but may also be applied to a reverse channel (from mobile communication terminal to base station). The case of transmitting RLP frame data of the reverse channel is omitted here.

1 is a block diagram for transmitting a retransmission request signal in a radio link protocol layer of a mobile communication system according to the present invention. Hereinafter, a block configuration, an operation, a signal, and the like according to a preferred embodiment of the present invention will be described in detail with reference to FIG. 1.

First, the hierarchical structures of the mobile communication terminal 110 and the base station 120 illustrated in FIG. 1 will be described. In addition, FIG. 1 illustrates only the hierarchical structure of the mobile communication terminal 110 and the base station 120 required for the present invention, and only the hierarchical structure will be described except in the following description.

The mobile communication terminal 110 includes a radio link protocol layer 111, a MAC layer 112, and a PHY layer 113. The physical layer 113 performs a process for transferring the frame data transferred from the RLP layer 111 through the MAC layer 112 in a wireless state and transmits the frame data to the base station 120. In addition, the physical layer 113 decodes the received frame upon reception of the frame data from the base station 120 and transfers it to the RLP layer 111 through the MAC layer 112. The base station 120 also includes an RLP layer 121 and a physical layer 122. In general, the base station 120 also has a MAC layer. As shown in FIG. 1, when frame data is transmitted from the base station 120 to the mobile communication terminal 120, that is, forward data transmission will be described. In particular, a case in which retransmission is performed during forward data transmission will be described.

When data to be transmitted is generated, the RLP layer of the base station 120 configures radio link protocol frame data (RLP frame data), and transmits it to the physical layer 122. Then, the physical layer 122 encodes the frame data received from the RLP layer 121 as described above, and transfers it to the mobile communication terminal 110 through the established channel. As such, when data is transmitted from the physical layer 122 of the base station 120 to the physical layer 113 of the mobile communication terminal 110, the physical layer 113 of the mobile communication terminal 110 decodes the received encoded frame. do. When the data of the frame received as a result of the decoding is normally received, that is, received without an error, the physical layer 113 transfers it to the RLP layer 111, which is a higher layer, through the MAC layer 112.

Meanwhile, the radio link protocol uses NAK based on the ARQ scheme to recover errors occurring on the radio channel. That is, if the RLP frame is not received, the RLP layer 111 of the mobile communication terminal 110 transmits a Nak frame requesting retransmission of the frame to the RLP of the base station 120, and receives the received The RLP of the base station 120 uses a method of retransmitting the requested frame. Here, the mobile communication terminal 110 drives the retransmission timer (abort timer) waiting for reception of the frame after transmitting the Nak. This is the time required until the mobile communication terminal 110 receives the retransmission frame after transmitting Nak. If the value of the retransmission timer is too short, the timer expires before the retransmission frame is received, thereby performing another operation, resulting in a failure to receive the retransmission frame. On the contrary, if the timer value is set too large, it takes too much time until the timer expires, which requires a large amount of buffer, and delays the data transferred to the upper level, thereby slowing down the processing speed of the upper application. Let's go.

After transmitting the RLP frame to the mobile communication terminal 110, the base station 120 drives a RLP flush timer. This is the time required for the base station 120 to receive the corresponding Nak after transmitting the RLP frame data. That is, after the base station 120 transmits the RLP frame to the mobile communication terminal 110, the mobile communication terminal 110 checks whether the RLP frame is received or whether the RLP frame error is not sufficient to receive the RLP frame or the RLP. If an error occurs in a frame, Nak is transmitted to the base station 120. At this time, if the base station 120 does not receive a Nak during the RLP flush timer, the base station 120 removes the corresponding RLP frame transmitted from the RLP buffer. Therefore, if the value of the RLP flush timer is set to a large value, it requires too much time until expiration of the timer, which wastes resources by requiring a large amount of buffers. On the contrary, if the value of the RLP flush timer is too short, the timer expires before the corresponding Nak is received, resulting in the inability to retransmit the RLP frame.

According to the present invention, the RLP buffer can be efficiently used if the retransmission timer (abort timer, flush timer) is set according to the state of the wireless channel. For example, in a good channel condition, a short timer value is used to shorten the RLP frame data in the RLP buffer. This is because Nak is less likely to be transmitted because the channel environment is good. On the contrary, in a bad channel condition, the timer value is set long to allow sufficient time for receiving Nak. This is because Nak is more likely to be transmitted because the channel environment is bad.

2 is a block diagram of an apparatus for dynamically setting a retransmission timer operating time in transmitting radio link protocol data in a mobile communication system according to the present invention.

Referring to FIG. 2, a device block diagram for dynamically setting a retransmission timer operation time in transmitting radio link protocol data in a mobile communication system will be described based on a forward link between the mobile communication terminal 210 and the base station 200. something to do.

The base station 200 includes a data rate control (DRC) allocator 204, an RLP retransmission timer 203, a control unit 202, and a communication unit 201 to perform retransmission communication using the RLP protocol.

The controller 202 controls the overall operation of the base station 200. For example, call processing and control of the mobile communication terminal 210 are performed, and data for handover and power control are collected from the mobile communication terminal. In particular, the RLP retransmission timer 203 is controlled and operated in consideration of the channel state with the mobile communication terminal (MS) 210 in addition to the normal function.

The communication unit 201 performs baseband processing by decreasing the frequency of the radio frequency signal received through the antenna, and transmits the frequency through the antenna by raising the baseband signal. For example, in the case of transmission, channel coding and spreading of data to be transmitted are performed, and in the case of reception, the function of despreading and channel decoding of a received signal is performed. .

The DRC allocator 204 measures the carrier to interference (C / I) of the current network state and uses the DRC channel of the reverse link to request a desired data rate. Allocate a transmission rate per user.

Table 1 below shows transmission rates and packet lengths (slots) according to DRC values.

The RLP retransmission timer 203 determines a timer value based on the DRC value allocated by the DRC allocator 204 and provides the timer value to the controller 2032.

Table 2 below shows the transmission rate and retransmission timer operation time according to the DRC value.

The mobile communication terminal (MS) 210 may communicate with one or more base stations over a forward and / or reverse link at any given moment, depending on whether the terminal is active, whether soft handoff is supported, and whether it is soft handoff. It may be. The forward link (ie downlink) refers to transmission from the base station to the terminal, and the reverse link (ie uplink) refers to transmission from the terminal to the base station.

Referring to FIG. 2, the base station 200 operates at a timer time of t1 for an MS1 in an area having a very good wireless channel environment, and operates at a timer time of t2 for an MS2 in an area having a better channel environment than the MS1. This worst MS_N is operated with a timer time of t3. Good and bad channel environment can be judged by C / I. Here, t1, t2, and t3 are RLP retransmission timer operation times operated after the base station 200 transmits RLP frame data. Assume that C / I of MS1> C / I of MS3> C / I of MS3 has a relationship of t1 <t2> t3.

3 is a flowchart illustrating an RLP transmission using a retransmission timer time dynamically in transmitting radio link protocol data in a mobile communication system according to an exemplary embodiment of the present invention.

Referring to FIG. 3, the RLP transmission procedure using the retransmission timer time dynamically in transmitting radio link protocol data in the mobile communication system first receives a packet from an upper node in step 300. The upper node refers to an exchange station controlling a base station.

In step 302, the base station 200 generates an RLP packet and transmits the generated RLP packet to the mobile communication terminal 210.

In step 304, the base station 200 starts the RLP retransmission timer based on the DRC. Here, the RLP retransmission timer is a timer for retransmission, and an operation time is determined by a DRC value requesting a data rate from the mobile communication terminal 110 through a DRC channel. For example, when the DRC value is Ox1, the transfer rate is 38.4kbps and the timer operation time is 4 seconds. When the DRC value is Oxc, the data rate is 2457.6 kbps and the timer operation time is 0.5 seconds. This means that a high data rate means that the wireless channel environment is good, and a good channel state means that the probability of sending Nak is low because the error probability of the RLP frame data is low. Accordingly, the base station 200 sets a short timer operation time for transmitting Nak when the mobile communication terminal 210 requests a high data rate, and sets a long timer operation time for a low data rate.

In step 306, it is checked whether the RLP retransmission timer has expired. The expiration of the RLP retransmission timer means that the base station 200 transmits RLP frame data and does not receive a response from the mobile communication terminal 210 for a predetermined time. This means that the mobile communication terminal 210 normally receives the RLP frame data.

If the RLP retransmission timer expires in step 306, the corresponding RLP frame data is removed. After the timer expires, the mobile communication terminal 210 determines that the received RLP frame data is normally received, and then removes the RLP frame data transmitted from the RLP buffer.

In operation 314, the frame data is processed.

If the RLP retransmission timer has not expired in step 306, the flow proceeds to step 308 to determine whether Nak is received. Since the timer has not expired, it waits further until the mobile communication terminal sends Nak.

If Nak is received in step 308, the flow proceeds to step 310 to retransmit the RLP packet. The transmission of Nak is because there is an error in the received RLP frame data or the next RLP frame data has not been received for a predetermined time.

If Nak is not received in step 308, the flow proceeds to step 306 again.

The algorithm of the present invention is then terminated.

Meanwhile, in the detailed description of the present invention, specific embodiments have been described, but various modifications are possible without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined not only by the scope of the following claims, but also by the equivalents of the claims.

As described above, the present invention transmits the RLP frame data to the receiving terminal in the mobile communication system and dynamically sets the retransmission timer operation time according to the channel state, that is, the timer operation time is shortened where the data transmission rate is high. In this case, the RLP buffer efficiency can be improved by setting a long timer operation time in a low transfer rate.

Claims (14)

In the radio link protocol (RLP) frame data processing method of a mobile communication system, Calculating RLP retransmission timer operation time using DRC (Data Rate Control) value transmitted by the mobile communication terminal when RLP frame data is generated; Operating an RLP retransmission timer with the calculated timer operation time and transmitting the RLP frame data; And determining whether the RLP retransmission timer expires and removing the corresponding RLP frame data from the buffer when the RLP retransmission timer expires. The method of claim 1, And a timer operation time is long when the RLP retransmission timer operation time is a DRC value having a high transmission rate and a DRC value having a low transmission rate. The method of claim 1, And determining whether to receive a negative acknowledgment (NAK) when the RLP retransmission timer is in operation and retransmitting corresponding RLP frame data when the NAK is received. The method of claim 3, wherein And determining whether to receive the NAK, and if the NAK is not received, waiting until the RLP retransmission timer expires. In the radio link protocol (RLP) frame data processing base station of the mobile communication system, An RLP retransmission timer for calculating an RLP retransmission timer operation time using a DRC (Data Rate Control) value transmitted by the mobile communication terminal and operating the RLP retransmission timer with the calculated timer operation time when the RLP frame data is generated; And a controller for transmitting the RLP frame data through a communication unit, determining whether the RLP retransmission timer expires, and removing the corresponding RLP frame data from a buffer when the RLP retransmission timer expires. The method of claim 5, And a timer operation time is long when the RLP retransmission timer operation time is a DRC value having a high transmission rate and a timer operation time is long when the RLP retransmission timer operation time is a DRC value having a high transmission rate. The method of claim 5, And determining whether to receive the NAK when the RLP retransmission timer is in operation and retransmitting the corresponding RLP frame data upon receiving the NAK. The method of claim 7, wherein And determining whether to receive the NAK, and if the NAK is not received, waiting until the RLP retransmission timer expires. In a radio link protocol (RLP) frame data processing mobile communication terminal of a mobile communication system, An RLP retransmission timer for calculating an RLP retransmission timer operation time using a DRC (Data Rate Control) value and operating the RLP retransmission timer with the calculated timer operation time when RLP frame data is generated; And a controller which transmits the RLP frame data through a communication unit and determines whether the RLP retransmission timer expires and removes the corresponding RLP frame data from a buffer when the RLP retransmission timer expires. The method of claim 9, And a timer operation time is long when the RLP retransmission timer operation time is a DRC value having a high transmission rate and a timer operation time is short and a DRC value having a low transmission rate. The method of claim 9, And determining whether to receive the NAK when the RLP retransmission timer is in operation and retransmitting the corresponding RLP frame data when receiving the NAK. The method of claim 11, Determining whether to receive the NAK, and if the NAK is not received, waiting until the RLP retransmission timer expires. In a radio link protocol (RLP) frame data processing mobile communication system over a forward channel, When the RLP frame data is generated, the RLP retransmission timer operation time is calculated using the DRC (Data Rate Control) value transmitted by the mobile communication terminal, and the RLP retransmission timer is operated using the calculated timer operation time, and the RLP frame data And a base station for determining whether the RLP retransmission timer has expired and removing the corresponding RLP frame data from the buffer when the RLP retransmission timer expires. And a mobile communication terminal for transmitting Nak to the base station when the received RLP frame data is received from the base station and there is an error in the received RLP frame data or the RLP frame data is not received for a predetermined time. The method of claim 13, And a timer operation time is long when the RLP retransmission timer operation time is a DRC value having a high transmission rate and a timer operation time is short when the RLP retransmission timer operation time is a DRC value having a high transmission rate.

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