KR100306278B1 - Emboding method of radio rink protocal for efficient data transmission - Google Patents

Abstract

Using the proposed serial number reservation method and the radio link protocol proposed in the present invention using the split tree in the mobile communication system performing the packet data service can ensure proper transmission of the data rate that can be changed variously.

Description

TECHNICAL FIELD [0001] The present invention relates to a radio link protocol for efficiently transmitting data,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a code division multiple access (CDMA) communication system, and more particularly, to a radio link protocol implementation method used for efficient data transmission in a wireless environment.

In general, a code division multiple access (UMD) mobile communication system has evolved from the IS-95 standard based on voice, and has evolved into the IMT-2000 standard capable of transmitting not only voice but high-speed data. According to the IMT-2000 standard, services such as high-quality voice, moving picture, and Internet search are possible. In the CDMA mobile communication system, since the maximum transmission speed of data is only 9.6kbps or 14.4kbps because it is voice-oriented, up to 2Mbps can be achieved in the IMT-2000 standard. Therefore, 256 times more data than the CDMA mobile communication system is transmitted once As shown in FIG.

In the CDMA mobile communication system, the radio link protocol is used to solve the data corruption occurring in the wireless environment. The radio link protocol is based on a frame having a length of 20 ms at a transmission rate of 9.6 kbps or 14.4 kbps or less, and has been proposed up to the current type 2.

The radio link protocol uses a retransmission method to transmit a lost data frame during transmission in a wireless environment by attaching a sequence number to each 20 ms frame. Since the sequence number used in the radio link protocol has a length of 8 bits, the maximum number of frames supported by the radio link protocol is 256.

If the rate is changed to be higher than the existing rate in the retransmission process of the radio link protocol, the retransmitted frame may be transmitted together with other frames, thereby enabling efficient transmission at a higher transmission rate. If the transmission rate is changed to be lower than the existing transmission rate during the retransmission process of the radio link protocol, the frame to be retransmitted must be divided into several frames to be transmitted at a low transmission rate.

In the retransmission process of the radio link protocol, when a frame is divided and transmitted, a maximum of three frames can be transmitted. In this case, the receiving side using the radio link protocol divides the transmitted frame into a maximum of three, assembles the transmitted frame back into the original frame, and uses it as if the original frame were received.

However, in the IMT-2000 standard, a maximum transmission rate of up to 2 Mbps, which is much faster than the maximum transmission rate of 9.6 Kbps or 14.4 Kbps supported by the radio link protocol, is possible. In addition, since the above-mentioned IMT-2000 standard defines all necessary transmission rates to provide various kinds of services, the number of supported transmission rates is much larger. Such a high transmission rate causes unnecessary burdens to users who use specific services, and adversely affects the overall system performance.

Therefore, it is an object of the present invention to provide a radio link protocol capable of supporting a mobile terminal with a high-speed transmission rate of 9.6 Kbps or 14.4 Kbps or higher, In order to provide a new serial number generation method.

Another object of the present invention is to provide a method for efficiently retransmitting data lost during transmission while protecting data transmitted during a period when a terminal and a system use the new serial number generation method in the mobile communication system.

It is another object of the present invention to provide a method of effectively retransmitting lost data during transmission while protecting data transmitted during a data rate change of a wireless channel connected during a data transmission between a terminal and a system in a mobile communication system .

It is another object of the present invention to provide a method for generating a serial number optimized for a data rate supported by a terminal in a mobile communication system, thereby reducing unnecessary burdens imposed on a terminal and a system and increasing transmission efficiency.

It is another object of the present invention to provide a new high-speed transmission radio protocol that guarantees full compatibility with a terminal supporting the existing radio link protocol type 2 in a mobile communication system.

According to an aspect of the present invention, there is provided a packet data communication method in a mobile communication system, which uses an extended serial number generation method different from the serial number generation method used in the existing radio link protocol .

Brief Description of the Drawings Fig. 1 is a diagram showing an example of creating a split tree according to a method of obtaining a split tree proposed by the present invention

2 is a diagram showing an example in which the number of necessary serial numbers is obtained at each node of the divided tree according to the embodiment of the present invention

FIG. 3 is a diagram showing an example in which a divided tree with a serial number is obtained for a serial number 7 frame according to a procedure of obtaining a divided tree having a serial number for the frame of the serial number r proposed in the present invention

4 is a diagram illustrating an example of creating a NAK entry included in a NAK control frame according to an embodiment of the present invention and an example of obtaining an area of a piece to be sent for a received NAK entry

5 is a block diagram of a radio link protocol implementation according to an embodiment of the present invention.

FIG. 6A is a flowchart of an operation control performed by the transmitting side frame generation layer 12 of FIG.

FIG. 6B is a flowchart of an operation control performed by the transmission side fragment and re-combination layer 14 of FIG.

7A is a flowchart of an operation control performed by the receiving-side transmitting unit 30 of FIG. 5

FIG. 7B is a flowchart of the operation control performed by the receiving-side receiver 40 in FIG.

8 is a diagram for explaining the concept of a major transmit rate, a minor transmit rate, and a rate set according to an embodiment of the present invention;

In order to efficiently perform data communication in a mobile communication system, a new serial number generation method capable of preventing loss of data in a wireless environment in which a data rate is constantly changed is needed. The new serial number generation method developed for this purpose should be compatible with the existing radio link protocol. Table 1 below shows the transmission rates supported by the IMT-2000 standard and the maximum frame sizes allowed at each transmission rate.

IMT-2000 system rate and frame size IMT-2000 system transmission rate Frame size IMT-2000 system transmission rate Frame size 9.6 Kbps 21 bytes 14.4 Kbps 33 bytes 19.2 Kbps 45 bytes 28.8 Kbps 69 bytes 38.4 Kbps 93 bytes 57.6 Kbps 141 bytes 76.8 Kbps 189 bytes 115.2 Kbps 285 bytes 153.6 Kbps 381 bytes 230.4 Kbps 573 bytes 307.2 Kbps 765 bytes 460.8 Kbps 1149 bytes 614.4 Kbps 1533 bytes 921.6 Kbps 2301 bytes 1036.8 Kbps 2589 bytes 1036.8 Kbps 2589 bytes 1228.8 Kbps 3069 bytes 1843.2 Kbps 4605 bytes 2073.8 Kbps 5181 bytes 2073.6 Kbps 5181 bytes 2457.8 Kbps 6141 bytes

In order to prevent data loss when the data rate is changed while supporting the various data rates, a large radio link protocol frame transmitted at a high data rate should be divided into a plurality of frames at a low data rate. In the conventional radio link protocol, a maximum of three pieces of segmentation and reassembly schemes have been proposed. However, as can be seen from Table 1, it is possible to divide up to 10 or more transmission rates and hundreds This fragment and recombination method can not be a suitable alternative, given the presence of the case.

In the embodiment of the present invention, when a large radio link protocol frame is divided without using such a fragment and re-combination method, unlike the existing radio link protocol, by assigning a unique serial number to each divided block, Protect as much as possible and ensure that only the necessary parts are retransmitted.

In order to assign a unique serial number to each of the divided blocks, it is not necessary to use the necessary serial number in another block or frame. Therefore, when a large radio link protocol frame is created, there is a need to reserve a maximum number of serial numbers that are needed in advance, and to prevent other blocks or frames from using this serial number. This method will be referred to as 'serial number reservation method' in the present invention.

The serial number reservation method is a method of ensuring that only lost fragments can be retransmitted by assigning a serial number as many as the maximum number of fragments that can be divided when a radio link protocol frame is retransmitted. That is, when a radio link protocol frame having a serial number S is generated, a sequence number is allocated for the number S of frames, which is the number of the worst pieces that can be divided. For example, if a frame with a serial number of 6 occurs and there are three worst fragments that can be divided, serial numbers 6, 7, and 8 are reserved for frame 6. Therefore, the next frame will have serial number 9 and will be assigned 9, 10, and 11.

Consider the number of worst pieces needed in the process. The minimum number of pieces required when a frame is divided into fragments due to a change in data rate is L _OLD , which is the maximum data length that can be transmitted at the previous data rate, and L _NEW , which is the maximum data length that can be transmitted at the changed data rate. , <L _OLD / L _NEW >(<x> is an integer not less than x). The number of minimum fragments in the worst case where the transmission rate changes several times is divided into several fragments in order to retransmit the radio link protocol frame of the maximum size occurring at the highest transmission rate at the next highest transmission rate, Is divided into several small pieces to be retransmitted at the highest transmission rate, and this process is repeated, and at the lowest transmission rate, the divided pieces are divided again into the smallest pieces And it can be easily seen that the minimum number of pieces obtained in this case is the minimum number of pieces in the worst case.

The process of obtaining the minimum number can be easily solved by using a tree structure. In the present invention, a tree drawn in the process of finding the minimum number is called a 'segment tree'. The split tree can be drawn through the following process.

How to get split trees

1) First, the maximum length of data that can be transmitted for each supported transmission rate is determined according to the supported N transmission rates determined between the terminal and the system, and the values are sorted in descending order. In the present invention, I the values obtained in the alignment procedure call this _{L 1, L 2, ... L} N according to the order.

2) Let L ₁ denote the maximum length of data that can be sent at the highest data rate as the root node of the split tree. Thus, using the root node, you can send data with a maximum length of L ₁ . If N is greater than 1, repeat the next step 3) for L ₂ , _..., L _N.

3) Do the following for all of the previously obtained nodes. That is, let one of the above-obtained node as the value to which that node p and has the node p l., And this time the maximum length of transferable data in the data rate to be considered that L _i and, in this case <l / L _i> When the value is c and the value of [l / L _i ] is f, node f is added with f l _i nodes and (c - f) l mod L _i nodes as child nodes, where [x] Means an integer not greater than x, and < x > means an integer not less than x). For example, if the value of l is 7 and the value of L _i is 3, the child node of the root node has two L _i nodes, ie, a node with a value of 3 and a node with a value of 1 (l mod L _i ) One child node is a child node. Therefore, the number of child nodes of the node p in the example is three. In the above process, 'mod' is a modulus operation, that is, an operation to obtain the remainder divided.

The nodes obtained in the above procedure have L _i or (l mod L _i ) values, respectively. As with the previously obtained nodes, we can use the generated child nodes to send data having the length of each value, ie, L _i or (l mod L _i ).

Such a child node addition operation may be performed for all of the previously obtained nodes.

4) If the above step 3) is repeated for the maximum lengths L ₂ , _..., L _N of all given transferable data, the operation is completed. At this time, the obtained result becomes the desired split tree, and the number of leaf nodes of the split tree becomes the minimum number of pieces in the worst case for the supported data rates between the terminal and the system.

The supported N transmission rates determined between the terminal and the system mentioned above are defined as a set of transmission rates that can be supported for the current service determined by negotiating between the terminal and the system among all the supportable transmission rates of the defined IMT- . For example, if a terminal with limited performance requests a service, the terminal and the system may decide to use only three transmission rates of 9.6 Kbps, 19.2 Kbps, and 38.4 Kbps. In this case, the three transmission rates of 9.6 Kbps, 19.2 Kbps and 38.4 Kbps are called three supported transmission rates determined between the terminal and the system. FIG. 1 shows an example of dividing trees by performing the above-described process when the above-described three rates are supported between the terminal and the system.

The procedure for obtaining the split tree with respect to the above three transmission rates is as follows. First, a maximum length of 93 bytes at 38.4 Kbps is regarded as a root node. For the obtained data transmission length of 45 bytes at the obtained root node of 19.2 Kbps, And the f value is 2, 93 bytes are added to the two 45-byte nodes, and 93 mod 45, that is, one node of 3 bytes is added as the child node. Repeat the above procedure for the three nodes and the maximum length of 21 bytes at 9.6 Kbps. The first and second 45-byte nodes have two 21-byte nodes and one 3-byte node as child nodes, Since a 3-byte node has a c value of 1 and an f value of 0, it has 3 mod 2 = 1, that is, only one 3-byte node as a child node.

As shown in the above example and FIG. 1, terminals and systems supporting three transmission rates of 9.6 Kbps, 19.2 Kbps and 38.4 Kbps have at least 7 pieces in the worst case, It is possible to retransmit the fragments even when the transmission rate is changed. FIG. 2 shows the number of serial numbers required for each node in the split tree obtained in FIG.

In FIG. 2, it can be seen that seven serial numbers are required since the root node capable of transmitting a maximum of 93 bytes has seven leaf nodes. If 93 bytes of information transmitted at the transmission rate of 38.4 Kbps is retransmitted at 19.2 Kbps, 93 bytes of information should be divided into three pieces of 45 bytes, 45 bytes and 3 bytes, respectively. When serial numbers are attached to each of the above pieces, it is necessary to allocate them by dividing them by seven numbers assigned to the root node. When the number of leaf nodes of each piece is found, 3 pieces of 45 byte pieces and 3 pieces of 3 byte pieces , So if you assign 3, 3, or 1 serial numbers in order, you will be able to transmit using the assigned serial number, even if the transmission rate drops from 19.2Kbps to 9.6Kbps. In fact, when the transmission rate is lowered from 19.2 Kbps to 9.6 Kbps, the 45-byte fragment is divided into three fragments of 21 bytes, 21 bytes, and 3 bytes, and the 3-byte fragment is transmitted without division. In Table 2, when retransmitting the frame of the serial number 7 transmitted at 38.4 Kbps with the divided tree obtained in FIG. 2, the number of pieces generated for each data rate and the number of serial numbers allocated to the pieces, In FIG. 3, a serial number for each piece is shown along with a split tree.

Transfer rate piece Number of assigned serial numbers Serial number attached 38.4 Kbps 93 bytes 7 No. 7 19.2 Kbps 45 bytes 45 bytes 3 bytes 3 3 1 7 times 10 times 13 times 9.6 Kbps 21 bytes 21 bytes 3 bytes 21 bytes 21 bytes 3 bytes 3 bytes 1 1 1 1 1 1 1 7 times 8 times 9 times 10 times 11 times 12 times 13 times

FIG. 3 shows an example in which a root node obtains a serial number to be owned by each node when the node has the serial number 7, based on the obtained split tree. Next, we show how to obtain these serial numbers.

Sequence number The process of obtaining a split tree with a serial number for frame r

1) First, the number of required serial numbers is obtained for each node. The number of serial numbers required is the number of leaf nodes of the subtree tree obtained when a sub-tree with each node as its root node is placed on the split tree. In other words, the number of required serial numbers of a node refers to the number of all leaf nodes that have themselves as an ancestor nodes. FIG. 2 shows an example in which the number of serial numbers necessary for each node in the split tree shown in FIG. 1 is obtained through the above definition.

2) Let the serial number attached to the root node be r and the root node be p.

3) Let the leftmost node among the child nodes of the node p be q. The serial number r of the node p is given as the serial number of the node q. If the node p is a leaf node of the split tree, the process of obtaining the split tree with the serial number is completed.

4) The serial number of the node q to which the serial number is added is added to the serial number of the right node of the node q plus the number of necessary serial numbers stored in the node q. That is, if the serial number of the node q is r and the number of necessary serial numbers of the node q is a, r + a is assigned as a serial number to the right node of the node q.

5) If the right node of the node q does not exist, the process goes to the next step. However, if there is a right node of the node q, the right node is again set to q, and the process of step 4) is performed.

6) Let p be the child node at the leftmost of the node p. We perform steps 3), 4) and 5) for the new node p.

As can be seen from the split tree with the serial number obtained in FIG. 3, the leaf nodes of the split tree have sequential serial numbers. In addition, in FIG. 3, it can be seen that nodes other than the leaf node allocate the serial number of the right node of the node from the leftmost node to the value increased from the serial number of the node by the required number of the serial number. Also, as shown in FIG. 3, the leftmost nodes of the partitioned tree with serial numbers all have the same serial number as the root node.

Therefore, if the receiver requests retransmission for a frame having the serial number r, the sender and the receiver can form a split tree having a serial number for the r-th frame as shown in FIG. 4, The number of pieces to arrive, the size of each piece, and the serial number to be attached can be predicted according to the transmission rate. Therefore, the transmitting side and the receiving side can know which pieces have been lost even if several pieces are lost during the retransmission, and therefore, the retransmission efficiency can be greatly improved because the retransmission can be requested only for the lost pieces. Since the fragments are serialized in the same way as the frames, there is no need to define a new format for the fragments, and the fragments can be processed in the same manner as the frames, so that the overall protocol can be simply configured.

On the transmitting side, as can be seen in the above process, when a new frame is to be transmitted, the serial number is assigned to a multiple of the number of leaf nodes of the obtained split tree. In the case of supporting the above three transmission rates of 38.4 Kbps, 19.2 Kbps, and 9.6 Kbps, the number of leaf nodes of the split tree is 7. Therefore, a new frame is first assigned a serial number of 0, and a new frame is reserved for 0 to 7 serial numbers: 0, 1, 2, 3, 4, 5 and 6. Therefore, the next frame that occurs next will be assigned the next serial number 7, and the serial numbers 7, 8, 9, 10, 11, 12, and 13 are reserved. The above example is summarized in the general case, and the following procedure is performed.

Procedure for assigning a serial number to a new frame

1) Let S be the variable that stores the current serial number and s be the stored value. Let the split tree be obtained according to the procedure defined in the method for obtaining the split tree, and let l be the number of leaf nodes of the split tree obtained.

2) When a new frame occurs, the sender assigns the value s stored in the serial number variable S to the serial number of the new frame. The sender then increments the serial number variable S by the number of leaf nodes l of the split tree obtained previously and reserves the serial numbers necessary for the newly generated frame. Therefore, the sequence number to be assigned to the next new frame to be generated will be s + l.

As can be seen from the above procedure, the sender always increases the serial number variable by the number of leaf nodes of the split tree regardless of the transmission rate. Therefore, newly generated frames will always have a serial number, which is a multiple of the leaf node number of the split tree regardless of the transmission rate. Referring to FIG. 3, the first frame of the newly generated sequence number is # 7 (= a multiple of the number of leaf nodes) regardless of whether the current transmission rate is 38.4 Kbps, 19.2 Kbps, or 9.6 Kbps. , And the frame to be generated next will be assigned a serial number # 14 (twice the number of leaf nodes) irrespective of the transmission rate at that time. This concept will be referred to as a &quot; regular serial number generation method &quot;. Using the regular serial number generation method, the newly generated serial numbers are increased regularly so that the transmitting side and the receiving side can operate in an easier way.

On the receiving side, when fragments re-transmitted in the above process are lost, a retransmission is requested using a NAK entry as in the existing RLP protocol. In the above process, since the only means for identifying the pieces is a serial number attached to each piece, the receiving side records the serial number of the piece in the NAK entry, thereby requesting the transmitting side to retransmit the necessary pieces as in the existing RLP (Radio Link Protocol). However, as shown in FIG. 3, since the serial number of the parent node is the same as the serial number of the leftmost node, if the receiving side writes the serial number in the NAK entry, the retransmission request for the parent node or the retransmission for the child node The request is not known by the transmitting side. This phenomenon will be referred to as 'NAK entry ambiguity problem' in the present invention.

In order to solve the NAK entry ambiguity problem, it is necessary to give a different serial number to each node of the split tree, but in this case, the number of necessary serial numbers is increased too much. Therefore, the present invention uses a leaf node serial number in the NAK entry . In other words, since the leaf nodes of the split tree have different serial numbers, they can be distinguished from each other in any case. By combining leaf nodes, it is possible to create an ancestor node. Therefore, a leaf node of the split tree, NAK entries are created with numbers. Fig. 4 shows an example of solving the NAK entry ambiguity problem using this NAK entry configuration method.

In FIG. 4, in a configuration supporting three transmission rates of 38.4 Kbps, 19.2 Kbps, and 9.6 Kbps, when the first piece sent when the serial number 7 frame is retransmitted at 19.2 Kbps, that is, the serial number 7 is lost, NAK entries created by the user are shown. The serial number 7 at 19.2 Kbps is the part that retransmits the foremost 45 bytes from 93 bytes of 38.4 Kbps. It contains the serial numbers 7, 8, and 9 pieces in the leaf node of the split tree. Therefore, in order to solve the NAK entry ambiguity problem, the receiving side inserts the serial numbers 7, 8, and 9 assigned to the smallest pieces into the NAK entry as described above. On the transmitting side, when three NAK entries 7, 8, and 9 arrive, retransmission is performed in the most appropriate manner at the current data rate. That is, if the current transmission rate is 19.2 Kbps, the 7 pieces of 45 bytes which are collected at the minimum pieces 7, 8 and 9 are retransmitted. If the current transmission rate is 9.6 Kbps, 7 pieces of 21 bytes and 8 pieces and 21 It retransmits three times with 9 pieces of bytes. The following shows the method of creating the NAK entry on the receiving side and the retransmission method on the transmitting side.

How to create a NAK entry

1) Let p be a piece that requires the sender to retransmit, and let s be the serial number assigned to the piece. If the fragment requesting retransmission corresponds to the first frame to be transmitted, fragment p will be the root node of the split tree. If the fragment requesting retransmission is a fragment that has already requested retransmission, as described above, the receiver will request the retransmission only for the leaf node of the split tree, so this fragment will be the leaf node of the split tree. Thus, in all cases, the receiver knows where the fragment is located in the split tree that will require retransmission.

2) The number of the serial numbers assigned to the piece p is obtained from the split tree. As described above, the number of serial numbers necessary for each node is stored in the split tree, and the number of serial numbers allocated to the fragment p in the split tree can be obtained. Let a be the number of assigned serial numbers obtained.

3) Add a number of NAK entries in order starting from the serial number s assigned to the piece p. That is, s, s + 1, s + 2, ..., s + a-1 are added as NAK entries.

The important thing in the above process is that the serial number of the leaf node of the split tree is added to the NAK entry. This is because the number of serial numbers stored in the piece p becomes the number of leaf nodes as seen from the split tree.

When a piece or frame to be retransmitted is generated on the receiving side, a NAK entry is generated using the NAK entry creation method. When the NAK entry creation for all pieces or frames to be retransmitted is completed, the receiving side stores the generated NAK entry in the NAK list, creates a NAK control frame using the NAK entry, and sends the control frame to the transmitting side.

The transmitting side receiving the NAK control frame retransmits the pieces desired by the receiving side using the recorded NAK entry. The sender first finds out in which frame the fragment desired by the receiver is generated in the sequence number stored in the NAK entry. Since the serial number of all the frames is a multiple of the number of leaf nodes of the split tree as described above, if the serial number stored in the NAK entry is s and the number of leaf nodes of the split tree is l, the frame having the fragment designated by the NAK entry Will be the value of [s / l], where [x] is an integer not greater than x.

A divided tree having a serial number is obtained by using a method of obtaining a divided tree having the above-mentioned serial number with respect to the serial number of the frame obtained in the above process. In the obtained split tree, the position of the split tree leaf node specified by the serial number stored in the above NAK entry can be known.

The following shows a method of generating a retransmission frame to be performed on the transmission side.

How to Create a Retransmission Frame

1) When the sender receives the NAK control frame, all the NAK entries contained in the received NAK control frame are put into the retransmission queue in order.

2) The sender extracts the NAK entry at the head of the retransmission queue. The extracted NAK entry is used to find the fragment having the serial number of the NAK entry as described above. That is, the serial number of the frame to which the piece having the serial number of the NAK entry belongs is obtained by the above method, and the split tree having the serial number is obtained based on the obtained serial number of the frame, A piece having the above-mentioned serial number can be found. Let F be the frame obtained at this time, and let p be the node having the serial number of the obtained NAK entry.

3) If the node p is not the node corresponding to the current data rate, and the serial number of the node p and the serial number of the parent node of the node p are equal to each other, it is checked whether there are sibling nodes of the node p in the retransmission queue . Here, the sibling node refers to a node having the same parent node as a certain node. If all the siblings of the node p are present in the retransmission queue and the desired fragment is found to be the parent node of the node p, the parent node of the node p is denoted by p, Lt; / RTI &gt;

If any one of the sibling nodes of the node p does not exist in the retransmission queue, the desired piece in the receiving side is the node p, and the process proceeds to the next step.

If the node p is the node corresponding to the current data rate or the parent node of the node p is different from the parent node, the procedure goes to the next step.

4) Based on the obtained divided tree and the obtained information of the node p, an area occupied by the node p obtained in the frame F is obtained. When the area is found, a retransmission frame is created with the area obtained. If the determined area is the end of the frame F, the END field of the retransmission frame is set to 1 and all NAK entries corresponding to the empty area of the frame F are deleted from the retransmission queue. If the obtained area is not the end of the frame F, the END field of the retransmission frame is set to zero. When the process is completed, the procedure of generating a retransmission frame is completed.

In the above-described retransmission frame generation method, a node corresponding to the current data rate refers to all nodes existing at a height corresponding to the current data rate in the split tree. That is, in the split tree, the root node corresponds to the data rate at which the data rate that can be transmitted among the data rates determined to support the current data rate between the terminal and the system is the largest. Likewise, the child nodes of the root node correspond to the second highest data rate among the data rates determined to support the current data rate between the terminal and the system. As a result, among the data rates determined to support the current rate between the terminal and the system, the nodes located in the L-th layer from the root node correspond to the data rate at which the data length is the L + 1th largest. Note that the root node is located at the 0th layer from the root node, and the child nodes of the root node are located in the first layer from the root node.

Therefore, if the data length that can be transmitted at the current data rate is L + 1th among the data rates determined to be supported between the mobile station and the system, the nodes corresponding to the current data rate are nodes located at the Lth layer from the root node.

It should be noted that if the retransmitted area is the last part of the frame, the END field is set to 1, otherwise it is set to 0. This is used to eliminate the occurrence of an empty piece when the frame contains only small data. For example, suppose that the terminal and the system support 38.4 Kbps, 19.2 Kbps, and 9.6 Kbps, respectively, as shown in FIG. As shown in FIG. 3, the serial number 7 frame is transmitted. Assume that the frame has only 50 bytes of data. If the serial number 7 frame is lost, the receiving side sends a NAK control frame having NAK entries 7, 8, 9, 10, 11, 12, 13 in order to retransmit the frame. At this time, if the transmission rate is lowered to 19.2 Kbps, the transmitter receiving the transmission should transmit the serial number 7 frame divided into three pieces of 45 bytes, 45 bytes, and 3 bytes, respectively. However, as described above, since the size of the serial number 7 frame is only 50 bytes, if only the first serial number 7 and the second serial number 10 are transmitted, all 50 bytes can be transmitted. Accordingly, in order not to transmit the piece of serial number 13, which is an unnecessary empty piece, the END field is set to 1 for the piece of the second serial number 10. Then, as described above, the serial number 13, which is the NAK entry corresponding to the empty area of the serial number 7 frame, is removed from the retransmission queue. In the present invention, a phenomenon in which blank pieces are generated when a frame having a small size is retransmitted will be referred to as &quot; a problem of retransmission of a blank piece &quot;.

The following shows the procedure for receiving and processing retransmission fragments sent by the sender on the receiving side.

The received retransmission frame processing method

1) When a retransmitted fragment arrives, first look at the size and serial number of the piece of data. Based on the serial number of the piece and the process described above, a split tree with a serial number is obtained. That is, a method is used in which a frame including a piece is obtained through the serial number of the piece and a divided tree with the serial number is obtained with respect to the serial number of the obtained frame. The split tree obtained, the serial number of the piece, and the size of the piece can be used to obtain a node of the split tree specified by the serial number of the piece. If there is no node of the split tree matching the size of the piece, the leaf node of the split tree having the serial number of the piece becomes the node coinciding with the one piece.

2) The leaf node serial numbers of all the split trees having the ancestor node obtained in the above step 1) are removed from the NAK list.

3) If the END field of the retransmitted piece is 1, serial numbers greater than the serial number of the retransmitted piece are removed from the NAK list among all the leaf node serial numbers of the split tree.

As can be seen from the received retransmission frame processing method, if the END field of the received retransmission frame is 1, NAK entries corresponding to the empty fragment are removed from the NAK list, thereby preventing unnecessary empty fragments from being requested again.

The existing radio link protocol type 2 supports fragmentation and reassembly. Accordingly, the present invention proposes a concept of a major transmit rate, a minor transmit rate, and a rate set in order to maintain compatibility with this concept. FIG. 8 is a diagram for explaining the concept of a major transmit rate, a minor transmit rate, and a rate set according to an embodiment of the present invention. Referring to FIG. 8, the supported transmission rates are divided into a plurality of transmission rate sets, that is, divided into transmission rate sets A, B, and C. The transmission rate set includes one main transmission rate M and several sub transmission rates m Let's have it. The main transmission rate M means the highest transmission rate in the rate set and the remaining transmission rate m has a lower transmission rate than the main transmission rate.

In order to support the radio link protocol type 2 as described above, in the present invention, the above-described transmission set is configured for the transmission rate between the terminal and the system, and the following rules are applied according to the current transmission rate.

Determine the retransmission scheme based on the rate set and the current rate

1) A piece to be retransmitted is created using the above-mentioned serial number reservation method and the split tree based on the main data rate of the data rate set to which the current data rate belongs.

2) If the current transmission rate is the primary transmission rate, the retransmission fragment generated using the above-described serial number reservation method and the split tree is transmitted as it is.

3) If the current transmission rate is a transmission rate, the retransmission fragment generated using the above-described serial number reservation method and the split tree is divided and transmitted using the fragment and re-combination method defined by the existing radio link protocol type 2.

That is, for the data rate set 1 defined in IS-95-B, i.e., Rate Set 1 and Rate Set 2, i.e., Rate Set 2, the main data rates of the respective data rate sets are set to 9.6 Kbps and 14.4 Kbps, If the transmission rate is set to be negative, the radio link protocol of the present invention creates fragments to be retransmitted on the basis of the respective primary transmission rates, and if the current transmission rate is a negative transmission rate for the generated fragments, retransmission is performed using the fragmentation and re- So that correct retransmission can be achieved.

In addition, since a terminal using the existing radio link protocol type 2 supports only one transmission rate set, there is only one main transmission rate supported by the terminal and the system. Therefore, a split tree is a tree in which only one root node exists. If the fragment and recombination method of the radio link protocol type 2 are used for the generated fragment, it is possible to smoothly support the terminal using the existing radio link protocol type 2.

All of the above procedures are collected and the new high-speed transmission radio link protocol proposed by the present invention is summarized as the configuration of FIG. FIG. 5 shows both the transmitting side and the receiving side. The transmitting side and the receiving side have the transmitting units 10 and 30 and the receiving units 20 and 40, respectively, and the operation will be described with reference to FIGS. 6A and 6B and FIGS. 7A and 7B.

FIG. 6A is a flowchart of operation control performed by the sender frame generation layer 12 of FIG. 5, and FIG. 6B is a flowchart of operation control performed by the sender fragment and reunion layer 14 of FIG. FIG. 7A is a flow chart of operation control performed by the receiving-side transmitting unit 30 of FIG. 5, and FIG. 7B is a flowchart of operation control performed by the receiving-side receiving unit 40 of FIG.

First, the configuration of the transmitting side and the performing operation thereof will be described.

The transmitting unit 10 on the transmitting side has two layers. The first layer is a frame generation layer 12, which transmits data desired to be transmitted in an upper layer or data desired to be retransmitted on the receiving side. The frame generation layer 12 has two states. One is a 'normal state' in which a new RLP frame for sending data to be transmitted is sent from an upper layer when a retransmission queue waiting for retransmission is empty and a 'normal state' in which a retransmission operation is performed when the retransmission queue is not empty (Retransmit) state. The frame generation layer initially allocates a serial number to a new frame according to a procedure of allocating a serial number to the new frame while being in the normal state, and repeats the operation of transmitting the serial number. If the NAK control frame is received from the receiving side, the frame generation layer 12 transits to the retransmission state. In the retransmission state, the frame generation layer continues to perform the retransmission frame generation method until all NAK entries are processed. When all the NAK entries are processed and the retransmission queue becomes empty, the frame generation layer returns to the normal state again.

The second layer of the transmitting side transmission unit 10 is the fragment and re-combination layer 14. In the fragment and re-combination layer 14, according to the transmission rate set and the retransmission determination method according to the current transmission rate, the retransmission frame created in the frame generation layer 12 is transmitted Decides whether to use the fragmentation and recombination method.

On the other hand, the transmitting side receiver 20 receives the NAK control frame from the receiving side and informs the frame generating layer 12 of the received NAK control frame.

The processes performed by the transmitting side transmitting unit 10 and the receiving unit 20 will be described in more detail with reference to FIGS. 6A and 6B.

The transmitting side frame generation layer 12 determines whether a NAK control frame is received in step 100 of FIG. 6A, and proceeds to step 102 if received. In step 102, the mobile station transitions to the retransmission state and proceeds to step 104. [ The transmitting side frame generation layer 12 generates a retransmission frame by performing the retransmission frame generation method in step 104 and proceeds to step 106 to transmit the retransmission frame to the fragmentation and reassembly layer 14. [ Thereafter, in step 106, it is determined whether the retransmission queue is empty. If the retransmission queue is empty, the process from step 104 is performed again. If the retransmission queue is not empty, the process returns to step 100 to determine whether a NAK control frame is received. If the NAK control frame is not received, the process proceeds to step 110 to determine whether data is generated. If the data is generated, the process proceeds to step 112, and the process shifts to the normal state. The transmitting side frame generation layer 12 creates a frame corresponding to the transmission rate in step 114 and assigns a serial number to the newly created frame, and then, in step 116, transmits the frame having the serial number to the fragment and re-

In the transmission side fragment and reassembly layer 14, the transmission side frame generation layer 12 determines in step 150 of FIG. 6B whether the frame sent in step 106 or step 116 is received. If the frame is received, the flow advances to step 152 to determine whether the current transmission rate is a secondary transmission rate. If the transmission rate is negative, the flow advances to step 154 and the frame is transmitted to the reception side using the fragmentation and re-combination method. However, if it is determined in step 152 that the current transmission rate is not the secondary transmission rate, the mobile station proceeds to step 156 and transmits the frame as it is.

Next, the configuration of the reception side and the operation performed thereby will be described.

The transmitting unit 30 on the receiving side creates a NAK entry according to the NAK entry creating method for the retransmission frame requested by the receiving side receiving unit 40, creates a NAK control frame including the NAK entry, and sends the NAK control frame to the transmitting side. If the retransmission is not performed after a predetermined time, the NAK control frame is transmitted again. If retransmission still fails, the receiver is notified of the retransmission failure.

The receiver 40 of the receiver observes the newly transmitted frames and requests retransmission of the missing frame if there is a missing frame. If the transmitting unit 30 of the receiving side notifies the retransmission failure, the receiving side transmits the remaining part to the upper layer excluding the missing frame. If a retransmitted frame arrives at the receiving side 40 of the receiving side, it performs processing according to the received retransmission frame processing method and informs the transmitting side of the receiving side that the retransmitted frame has arrived.

The processes performed by the receiving-side transmitting unit 30 and the receiving unit 40 will be described in more detail with reference to FIGS. 7A and 7B.

The receiver 40 of the receiving side determines whether a frame is received in step 250 of FIG. 7B. If the frame is received, it is determined in step 252 whether the received frame is a retransmission frame. If the frame is a retransmission frame, In step 254, the receiving-side receiving unit 40 notifies the receiving-side transmitting unit 30 that the NAK entry is deleted from the NAK list. If it is not the retransmission frame received in step 252, the process proceeds to step 256 and determines whether there is a missing frame among the received frames. If there is a missing frame, the process proceeds to step 258 and a retransmission request is made to the receiving side transmitting unit 30. [ If there is no missing frame, the flow advances to step 260 to process the received frame.

On the other hand, the receiving side transmitting unit 30 determines whether there is a retransmission request in the receiving side receiving unit 40 in step 200 of FIG. 7A, and if so, proceeds to step 202 of FIG. 7A to create a NAK entry by the NAK entry creating method. Then, in step 204 of FIG. 7A, the NAK control frame including the NAK entry is transmitted to the transmitting side. And the retransmission timer is driven as in step 208. [ Then, in step 210, it is determined whether the retransmission timer has expired before data is re-received. If the retransmission timer has expired, steps 212 to 206 are performed in steps 212 to 216, and then step 218 Go ahead. In step 218, the cancellation timer is activated. Then, it is determined whether or not the cancellation timer has expired before the data is re-received in step 220. If the cancellation timer has expired, step 222 is performed to delete the NAK entry from the NAK list.

FIG. 5 briefly shows all the procedures of the radio link protocol proposed in the present invention. Importantly, before using the radio link protocol proposed in the present invention, it is necessary to determine the data rate to be supported between the terminal and the system, and then, the split tree is first created, and then the operation of the radio link protocol is performed.

As described above, the present invention proposes an extended serial number generation method, a split tree, an END field, and various transmission and retransmission procedures when using a radio link protocol in an IMT-2000 system having various data rates, To support various types of terminals.

Claims (9)

Dividing a size of data in a frame transmitted at a maximum data rate into a plurality of frames transmitted at a minimum data rate, and setting each number of consecutive frames transmitted in one of the plurality of data rates, in consideration of the number of the divided frames, And allocating the number of transmission frames to the code division multiple access mobile communication apparatus. 2. The method of claim 1, wherein the allocated number is increased by a multiple of the number of divided frames and then added to each of the continuous frames. 3. The method of claim 2, further comprising the steps of: upon receipt of a retransmission request, confirming a data rate and a transmission frame at the time of transmission, determining a current data rate, allocating a number corresponding to a frame of the current data rate, And transmitting the number of transmission frames to the mobile station. Dividing a size of data in a frame transmitted at a maximum data rate into a plurality of frames transmitted at a minimum data rate and allocating a serial number to each of the divided frames; Determining a data transmission rate and a transmission frame at the time of transmission using the allocated serial number corresponding to the retransmission request and searching for a frame to be retransmitted; Determining a current data rate; And transmitting data in the frame to be retransmitted at the current data rate. 5. The method of claim 4, wherein if there is a missing frame among the frames at the time of transmission, the retransmission request is performed using a sequence number assigned corresponding to the lost frame. 5. The method of claim 4, wherein if the current data rate is lower than the transmission rate, the retransmitting frame is divided and the divided frames are retransmitted in order. 5. The method of claim 4, wherein before the retransmission request, the frames are incremented by a multiple of the number of the divided frames, and consecutive frames are transmitted in one of a plurality of data rates. 7. The method of claim 6, wherein information indicating that the frame is the last frame is inserted in the divided frames. A method for implementing a radio link protocol used in a data transmission method of a mobile communication system, Dividing a transmission rate into a transmission rate set to support a radio link protocol type 2, dividing a maximum transmission rate by a main transmission rate and a remaining transmission rate by a sub transmission rate for each transmission rate set, Generating a frame fragment to be retransmitted according to the retransmission determination method according to the current frame rate and the current data rate; And transmitting the frame to the receiver using the respective fragment and re-combination schemes according to whether the current transmission rate is the secondary transmission rate or the primary transmission rate.