KR20020081529A - Method for combination of retransmitting slot in wireless telecommunication system and apparatus and method for receiving data using the same - Google Patents

Abstract

1. TECHNICAL FIELD OF THE INVENTION

The present invention relates to a retransmission slot combining method in a wireless communication system, an apparatus and method for receiving data using the same, and a computer readable recording medium storing a program for implementing the methods.

2. The technical problem to be solved by the invention

The present invention relates to a retransmission slot combining method for increasing performance by soft combining slots retransmitted during forward link data transmission in a wireless communication system, a data receiving apparatus and method using the same, and a program for realizing the methods. To provide a record medium.

3. Summary of Solution to Invention

The present invention provides a retransmission slot combining method in a wireless communication system, comprising: a first step of receiving each slot at a receiving end; Obtaining a strength of received power of each received slot; Estimating a weight for each strength of the received power; And a fourth step of multiplying the estimated weight by each received slot to recombine retransmitted slots based on the strength of received power.

4. Important uses of the invention

The present invention is used in the 1X EV-DO system.

Description

Method for combination of retransmitting slot in wireless telecommunication system and apparatus and method for receiving data using the same}

The present invention relates to a retransmission slot combining method, a data receiving apparatus and method using the same, and a computer readable recording medium recording a program for realizing the above method. Division Multiple Access) Retransmission in 1X EV-DO systems such as mobile telecommunication networks, next generation mobile telecommunication networks such as International Mobile Telecommunication (IMT-2000) and Universal Mobile Telecommunication Service (UMTS), which are currently being standardized in North America and Europe. The present invention relates to a method of improving reception performance and throughput of an entire system by recombining slots retransmitted in a poor channel environment based on a received signal power level.

1 is an exemplary configuration diagram of a general wireless communication network.

As shown in Fig. 1, a general wireless communication network (e.g., W-CDMA) includes a user equipment (UE) (e.g., asynchronous terminal) 10, a wireless network (RNS :). Radio Network Subsystem (eg, asynchronous radio network) 20 and a wireless communication core network (eg, GSM-MAP core network) 30 are organically connected. Here, the combining scheme of the retransmission slot is a technique applied between the mobile station 10 and the radio network 20, and is a technique used when a retransmission is requested from the receiving end to the transmitting end when there is an error in the received data.

Recently, the 1X EV-DO system has been actively studied as a kind of next generation high speed mobile data communication system since IMT-2000.

In case of the 1X EV-DO system based on CDMA, an error frame that cannot be recovered by an error correction technique by an turbo correction code, which is an error correction code, for high-speed packet data transmission in a poor wireless channel environment Automatic Retransmission ReQuest (ARQ) is used for this purpose.

In addition, in the 1X EV-DO system, each mobile station transmits the E _c / I _t information estimated in the forward pilot channel to the base station through the reverse DRC channel, and the base station based on this value provides an optimal data rate suitable for the current channel environment. Although it copes with wireless multimedia services that meet various data rates and quality of service (QoS) by selecting and transmitting data, in a poor wireless channel environment, it is required to request retransmission by automatic retransmission technique due to deterioration of reception performance. As a result, throughput of the entire system is lowered. The conventional data receiving process using this method is shown in FIG.

Specifically, as shown in FIG. 2, in the conventional data reception process, when a slot is received, a reception frame is generated, the generated frame is decoded, and the decoded frame is subjected to a cyclic redundancy check (CRC) error check. Check for errors and request automatic retransmission if a frame error occurs.

However, the forward channel of the 1X EV-DO system transmits data by multiple users using time division multiple (TDM), wherein transmission frame sizes exist in various forms from 1 to 16 slots. Since transmission frames larger than one slot are generated by repetition of the original transmission frame, the data interval in each slot has the same offset and the same user data is repeated, preventing one user from occupying the channel completely. In order to improve the efficiency of using the channel, three slots are transmitted by inserting the data into three slots.

This multi-slot packet transmission technique can improve the efficiency of channel use, but multiple slots generated in one transmission frame are combined with slots by other users over a relatively long time. Is sent. Therefore, when the channel changes rapidly, such as in a high-speed mobile environment, a later received slot is modulated by DRC channel information different from the current channel environment compared to the initially received slot, so that an error probability is increased and the throughput of the system is increased. There is this decreasing problem.

The present invention has been proposed to solve the above problems, a retransmission slot combining method for increasing performance by soft combining slots retransmitted during forward link data transmission in a wireless communication system, and an apparatus and method for receiving data using the same And a computer readable recording medium having recorded thereon a program for realizing the above methods.

1 is an exemplary configuration diagram of a general wireless communication system.

2 is a flowchart illustrating a process of receiving data using a conventional automatic retransmission technique.

3 is a diagram illustrating an embodiment of a retransmission slot combining method according to the present invention;

4 is a flowchart illustrating an embodiment of a data receiving method according to the present invention;

5 is a block diagram of an embodiment of a data receiving apparatus according to the present invention;

* Explanation of symbols for the main parts of the drawings

10: mobile station (UE) 20: radio network (RNS)

30: wireless communication core network

According to an aspect of the present invention, there is provided a retransmission slot combining method in a wireless communication system, comprising: a first step of receiving each slot at a receiving end; Obtaining a strength of received power of each received slot; Estimating a weight for each strength of the received power; And a fourth step of multiplying the estimated weight by each receiving slot to recombine the retransmitted slots based on the strength of the received power.

According to an aspect of the present invention, there is provided a data receiving apparatus in a wireless communication system, comprising: demodulation means for demodulating each slot received through an antenna to obtain strengths of received power; Soft recombination means for generating a frame by recombining the retransmitted slots according to the strengths of the received powers obtained by the demodulation means; Frame error correction means for correcting an error of a frame generated by the soft recombination means; Frame error checking means for checking an error of the frame and deleting a frame in which an error occurs with respect to a frame in which an error cannot be restored by the frame error correcting means; And automatic retransmission requesting means for requesting, by the transmitting end, to retransmit the corresponding frame in which the error has occurred, according to the inspection result of the frame error checking means.

In order to achieve the above object, the present invention provides a data receiving method in a wireless communication system, comprising: a first step of receiving a slot; If all slots have not been received, comparing the received power with a predetermined threshold; A third step of discarding the current slot if the current received power is less than or equal to the predetermined threshold value according to the comparison result of the second step; A fourth step of storing the current slot and the current received power in a buffer and waiting for reception in order to soft combine after receiving all slots if the current received power is equal to or greater than the predetermined threshold according to the comparison result of the second step. ; If all slots have been received, a fifth step of softly combining the respective receiving slots based on the respective received powers to generate a frame, then decoding the generated frame and checking for errors in the decoded frame; And a sixth step of requesting, by the transmitting end, to retransmit the corresponding frame in which the error has occurred, if a frame error occurs according to the inspection result of the fifth step.

The present invention may further comprise a seventh step of delivering received data to a higher layer when there is no error as a result of the frame error check of the fifth step.

The present invention for achieving the above object, a wireless communication system having a processor for retransmission slot coupling, a first function for receiving each slot at the receiving end; A second function of obtaining strengths of received power of each received slot; A third function of estimating a weight for each strength of the received power; And a computer-readable recording medium having recorded thereon a program for realizing a fourth function of multiplying the estimated weight by each received slot to recombine the retransmitted slots based on the strength of the received power.

In order to achieve the above object, the present invention provides a wireless communication system having a processor for data reception, comprising: a first function of receiving a slot; A second function of comparing received power to a predetermined threshold when all slots have not been received; A third function of discarding a current slot if a current received power is equal to or less than the predetermined threshold according to a comparison result of the second function; According to a result of the comparison of the second function, when the current received power is greater than or equal to the predetermined threshold, in order to soft-couple after receiving all slots, storing a current slot and the current received power in a buffer, and then waiting to receive the fourth function. function; A fifth function of soft combining the respective receiving slots based on the respective received powers to generate a frame when all slots have been received, and then decoding the generated frame and checking for errors in the decoded frame; And a computer readable recording medium having recorded thereon a program for realizing a sixth function that requires the transmitting end to retransmit the corresponding frame in which an error occurs when a frame error occurs according to the inspection result of the fifth function. do.

The present invention also provides a computer-readable recording medium having recorded thereon a program for further realizing a seventh function of delivering received data to a higher layer in the absence of an error according to the frame error check result of the fifth function. to provide.

The present invention applies a kind of retransmission-rake technique to the 1X EV-DO system to recombine slots retransmitted in a poor channel environment based on the power level of the received signal to improve reception performance and increase throughput of the entire system. It is intended to be applied to all mobile communication systems that intend to improve the performance in the future.

The above objects, features and advantages will become more apparent from the following detailed description taken in conjunction with the accompanying drawings. Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

3 illustrates a process of performing soft combining by assigning weights according to the received power based on the received power to two or more slots in which the same data is transmitted with a predetermined offset.

Data transmitted over two slots in a 1X EV-DO system is generated by repetition of the original transmission frame. Accordingly, the transmitted slots are transmitted with the same symbol loaded with a constant offset from each other.

For example, when the transmission is performed over two slots, a slot transmitted first in an n-th slot interval for one user is called {D _{n, 1} , D _{n, 2} , ..., D _{n, k} }. Assume that the second transmitted slot in the n + lth slot interval is {D _{n + l, 1} , D _{n + l, 2} , ..., D _{n + l, k} }. Here, l is a retransmission delay and 4 for 1X EV-DO system, and k is 2048 chips for 1X EV-DO system with the number of chips in 1 slot.

The weight estimated from the received power is {W _{n, 1} , W _{n, 2} , ..., W _{n, k} } in the case of the first slot and {W _{n + l, 1} , in the case of the second slot. Assuming that W _{n + l, 2} , ..., W _{n + l, k} }, the soft combined slots are generated by multiplying each receive slot by its respective weight.

In this case, an offset of the same data repeatedly carried in each slot should be taken into account. If the offset is 0, the soft-combined slot is represented by Equation 1 below.

{W _{n, 1} , W _{n, 2} , ..., W _{n, k} } · {D _{n, 1} , D _{n, 2} , ..., D _{n, k} } + {W _{n + l, 1} , W _{n + l, 2} , ..., W _{n + l, k} } · {D _{n + l, 1} , D _{n + l, 2} , ..., D _{n + l, k} } = {D ^{`</sup> <sub>n + l, 1</sub> , D <sup>`} _{n + l, 2} , ..., ^D` _{n + l, k} }

In addition, when the value of the estimated received power is less than a predetermined reference value, it is set to 0. If the wireless channel environment is excessively poor, the value of the corresponding slot is not reflected during soft coupling to prevent the spread of noise. In addition, if the appropriate over-sampling is performed when setting the weight estimated from the received power, more accurate estimation is possible, thereby improving reception performance.

An apparatus and method for receiving data using the soft combining method as described above will be described in more detail with reference to FIGS. 4 and 5.

When the data is received using the soft combining method, in a rapidly changing wireless channel environment such as a high speed mobile channel environment, the reception performance can be improved by soft combining the slots repeatedly transmitted in consideration of the reception power. In consideration of the improvement, the value of the reverse DRC channel transmitted from the mobile station to the base station can be set to a higher data rate, thereby increasing the throughput of the entire system.

4 is a flowchart illustrating a data receiving method according to an embodiment of the present invention, which illustrates a procedure of receiving data using a soft combining method of a retransmission slot.

First, when a slot is received (401), it is checked whether all slots have been received (402).

As a result of the inspection, when all slots have been received, each receiving slots are soft-combined based on their respective received powers (403) to generate a frame (404), then decoded the generated frames (405) and the decoded frames are CRC Error checking is performed through error checking (406). At this time, if no error occurs in the frame, the reception process is terminated. However, if a frame error occurs, automatic retransmission is requested (407), waiting for a new slot to arrive.

If all slots are not received, the received power is compared with a predetermined threshold (408). If the current received power is less than or equal to the threshold, the weight is set to 0 to prevent the spread of noise. Discard the slot (409). However, if the current received power is above the threshold, in order to soft combine after receiving all slots in step 403, after storing the current slot and the current received power in a buffer (410), when receiving a new slot. Wait until

Now, a data receiving apparatus using a soft combining method of a retransmission slot will be described with reference to FIG. 5.

As shown in FIG. 5, the data receiving apparatus according to the present invention includes a CDMA demodulator 52 which obtains strengths of received power by demodulating each slot received through an antenna 51 and a CDMA demodulator 52. According to the strengths of the received powers, the soft recombination unit 53 recombines the retransmitted slots to generate a frame, and the turbo decoder 54 corrects an error of a frame generated by the soft recombination unit 53. And a frame error check unit (CRC Check) 55 for checking an error of the frame and deleting the frame in which the error occurred with respect to a frame in which the error cannot be restored by the turbo decoder 54, and the frame error check unit 55. And an automatic retransmission request unit 56 for requesting the transmitting end to retransmit the corresponding frame in which the error has occurred.

Looking at the operation of the data receiving apparatus according to the present invention having the configuration as described above are as follows.

The signal received at the antenna 51 via the radio channel is demodulated via the CDMA demodulator 52, and in this process, the strength of the received power is estimated.

After receiving all slots, the soft recombination unit 53 generates a frame by soft recombination based on the estimated received power, and the generated frame is decoded through the turbo decoder 54 and finally, the frame error check unit ( 55) errors in the frame are checked. At this time, if an error occurs, the automatic retransmission request unit 56 requests automatic retransmission to the transmitting end, and if there is no error, passes the received data to the upper MAC layer.

As described above, the present invention can maximize the improvement of the reception performance by applying the weight based on the received power to the slots received along different time paths.

The method of the present invention as described above may be implemented as a program and stored in a computer-readable recording medium (CD-ROM, RAM, ROM, floppy disk, hard disk, magneto-optical disk, etc.).

The present invention described above is not limited to the above-described embodiments and the accompanying drawings, and various substitutions, modifications, and changes are possible in the art without departing from the technical spirit of the present invention. It will be apparent to those of ordinary knowledge.

As described above, the present invention can improve reception performance when data is transmitted on the forward link of the 1X EV-DO system, and the improvement of the reception performance prevents further retransmission, thereby changing rapidly such as a fast mobile channel. The transmission efficiency can be prevented by the automatic retransmission technique in a poor wireless channel environment, and the DRC information can be set in the forward DRC channel in consideration of the improvement of the reception performance, thereby increasing the throughput of the entire system. It can be effected.

Claims (20)

In the retransmission slot combining method in a wireless communication system, A first step of receiving each slot at a receiving end; Obtaining a strength of received power of each received slot; Estimating a weight for each strength of the received power; And A fourth step of multiplying the estimated weight by each received slot to recombine retransmitted slots based on the strength of received power Retransmission slot combining method in a wireless communication system comprising a. The method of claim 1, Each slot is At least two slots in which the same data is transmitted with a predetermined offset. The method according to claim 1 or 2, The third step, A method of combining retransmission slots in a wireless communication system, characterized in that over-sampling is performed when setting weights estimated from received power. The method according to claim 1 or 2, The third step, If the wireless channel environment is too poor when the received power is below a predetermined threshold, the weight is set to zero (0) so that the value of the corresponding slot is not reflected during soft coupling to prevent the spread of noise. Retransmission slot combining method in a wireless communication system, characterized in that. The method of claim 4, wherein The receiving end, In a rapidly changing wireless channel environment such as a high-speed mobile channel environment, a soft combining of repeatedly transmitted slots in consideration of the reception power improves the reception performance, and the reverse channel value transmitted from the mobile station to the base station in consideration of the improvement of the reception performance. Retransmission slot combining method in a wireless communication system, characterized in that to set a higher transmission rate. An apparatus for receiving data in a wireless communication system, Demodulation means for demodulating each slot received through an antenna to obtain strengths of received power; Soft recombination means for generating a frame by recombining the retransmitted slots according to the strengths of the received powers obtained by the demodulation means; Frame error correction means for correcting an error of a frame generated by the soft recombination means; Frame error checking means for checking an error of the frame and deleting a frame in which an error occurs with respect to a frame in which an error cannot be restored by the frame error correcting means; And Automatic retransmission request means for requesting the transmitting end to retransmit the corresponding frame in which the error occurs, according to the inspection result of the frame error check means. Data receiving apparatus in a wireless communication system comprising a. The method of claim 6, The frame error checking means, The apparatus for receiving data in a wireless communication system, characterized in that the received data is transmitted to a higher layer when there is no error as a result of the frame error check. The method of claim 6, The soft recombination means, And estimating a weight for each strength of the received power, multiplying the estimated weight by each received slot, and recombining the retransmitted slots based on the strength of the received power. The method according to any one of claims 6 to 8, Each slot is At least two slots in which the same data is transmitted with a predetermined offset. The method of claim 9, The soft recombination means, And over-sampling when setting the weight estimated from the received power. The method of claim 9, The soft recombination means, If the wireless channel environment is too poor when the received power is below a predetermined threshold, the weight is set to zero (0) so that the value of the corresponding slot is not reflected during soft coupling to prevent the spread of noise. A data receiving device in a wireless communication system, characterized in that. In the data receiving method in a wireless communication system, A first step of receiving a slot; If not all slots have been received, a second step of comparing the received power with a predetermined threshold; A third step of discarding the current slot if the current received power is equal to or less than the predetermined threshold according to the comparison result of the second step; According to the comparison result of the second step, in the case where the current received power is greater than or equal to the predetermined threshold, in order to soft combine after receiving all slots, a fourth slot for storing after receiving the current slot and the current received power in a buffer step; A fifth step of generating a frame by soft combining the respective receiving slots based on the respective received powers when all the slots have been received, and then decoding the generated frame and checking for errors in the decoded frame; And A sixth step of requesting, by the transmitting end, to retransmit the corresponding frame in which the error has occurred, when a frame error occurs according to the inspection result of the fifth step Data receiving method in a wireless communication system comprising a. The method of claim 12, A seventh step of transmitting the received data to a higher layer when there is no error according to the frame error check result of the fifth step Data receiving method in a wireless communication system further comprising. The method according to claim 12 or 13, The soft recombination process, Estimating a weight for each strength of the received power, multiplying the estimated weight by each received slot, and recombining the retransmitted slots based on the strength of the received power. The method of claim 14, Each slot is At least two slots in which the same data is transmitted with a predetermined offset. The method of claim 15, The soft recombination process, A method of receiving data in a wireless communication system, characterized in that over-sampling is performed when setting a weight estimated from received power. The method of claim 15, The third step, If the intensity of the received power is less than or equal to the predetermined threshold, the wireless channel environment is excessively poor. The weight is set to zero (0) so that the value of the corresponding slot is not reflected during soft coupling so that the spread of noise is prevented. A data receiving method in a wireless communication system, characterized in that the prevention. Wireless communication system having a processor for retransmission slot coupling, A first function of receiving each slot at a receiving end; A second function of obtaining strengths of received power of each received slot; A third function of estimating a weight for each strength of the received power; And A fourth function of multiplying the estimated weight by each received slot to recombine retransmitted slots based on the strength of received power A computer-readable recording medium having recorded thereon a program for realizing this. In a wireless communication system having a processor for receiving data, A first function of receiving a slot; A second function of comparing received power to a predetermined threshold when all slots have not been received; A third function of discarding a current slot if a current received power is equal to or less than the predetermined threshold according to a comparison result of the second function; According to a result of the comparison of the second function, when the current received power is greater than or equal to the predetermined threshold, in order to soft-couple after receiving all slots, storing a current slot and the current received power in a buffer, and then waiting to receive the fourth function. function; A fifth function of soft combining the respective receiving slots based on the respective received powers to generate a frame when all slots have been received, and then decoding the generated frame and checking for errors in the decoded frame; And A sixth function requesting the transmitting end to retransmit the corresponding frame in which the error has occurred, when a frame error has occurred according to the inspection result of the fifth function A computer-readable recording medium having recorded thereon a program for realizing this. The method of claim 19, A seventh function of transmitting received data to a higher layer when there is no error according to a frame error check result of the fifth function A computer-readable recording medium that records a program for further realization.