JP2011055369A - Radio base station device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a radio base station device which performs E-DPDCH decoding processing using E-DPCCH selected in receiving retransmission data. <P>SOLUTION: A radio base station device comprises: a receiving signal storage section 4 in which receiving processing of E-DPDCH including a data body is failed and it is determined to perform retransmission, a signal prior to despreading of receiving processing failed E-DPDCH is stored; an E-DPCCH selecting section 3 for selecting an optimal E-DPCCH decoding result based on line quality information in receiving each E-DPCCH from among an E-DPCCH decoding result in first transmission and all E-DPCCH decoding results in retransmission when performing demodulation processing on the E-DPDCH signal; and an E-DPDCH demodulating section 5 which uses control information matched to the E-DPCCH decoding result selected by the E-DPCCH selecting section 3 to perform demodulation processing on all the E-DPDCH signals in first transmission and in retransmission. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a radio base station apparatus in a cellular communication system.

  EUL (Enhanced Uplink) incorporating technologies such as HARQ (Hybrid Automatic Repeat Request) for the purpose of speeding up the uplink transmission of W-CDMA (Wideband Code Division Multiple Access) is a standard in 3GPP (3rd Generation Partnership Project) Release 6 It has become.

  In EUL, when a terminal performs data transmission, an E-DPDCH (E-DCH (Enhanced-Dedicated Channel) Dedicated Physical Data Channel) including a data body and an E-DPCCH (E-DPCCH including control information necessary for demodulation thereof) are transmitted. E-DCH Dedicated Physical Control Channel) is code-multiplexed and transmitted simultaneously. The control information transmitted by the E-DPCCH includes E-DPCI (E-DCH Transport Format Combination Indicator) indicating the transmission block size, spreading factor, number of multiplexed signals, etc., and RSN indicating the number of retransmissions in HARQ. (Retransmission Sequence Number) is included. After receiving the signal, the base station as a receiver first decodes the E-DPCCH, and decodes the E-DPDCH based on the result. Specifically, E-TFCI is used to know the spreading code of E-DPDCH.

  In the HARQ process in the EUL, the base station determines whether or not the decoding of the E-DPDCH data has been successful by a CRC (Cyclic Redundancy Check) added to the E-DPDCH. In this case, NACK (Negative Acknowledgment) is returned to the data transmission side (terminal), and the data that has failed in demodulation is held in the HARQ buffer. The terminal that receives the NACK retransmits the data, and the base station combines the retransmitted data and the data in the HARQ buffer and tries decoding again. When the data transfer fails, the time diversity effect can be obtained by combining the previous reception result with the latest reception result using the HARQ buffer.

  Here, the HARQ buffer is flushed under certain conditions. In EUL, the base station checks the consistency of the RSN value at the time of retransmission, and flushes the HARQ buffer if it does not comply with the rules. Such a technique is disclosed in the following Non-Patent Document 1.

  Patent Document 1 below discloses that the transmission block size at the time of retransmission is controlled to be the same as the transmission block size at the time of initial transmission of the data. That is, the same value is set for E-TFCI at the time of initial transmission and E-TFCI at the time of retransmission.

3GPP Release6 TS25.212 V6.10.0 2006

U. S. Patent Application Serial No. 11/968879

  However, according to the conventional technique (Non-Patent Document 1), if the RSN does not match at the time of retransmission data reception, the HARQ buffer is flushed and the received data is discarded. For this reason, there has been a problem that the effect of improving the HARQ transmission efficiency cannot be sufficiently obtained.

  Further, according to the conventional technique (Patent Document 1), when the E-TFCI received on the base station side is different from the initial transmission time, decoding of the E-DPCCH at the initial transmission or retransmission may have failed. There is sex. When decoding of E-DPCCH fails, data decoded using an incorrect E-TFCI exists in the HARQ buffer. Therefore, there has been a problem that the reception quality improvement effect assumed in HARQ combining cannot be obtained.

  Furthermore, the radio base station apparatus receives DPCCH, which is a non-EUL physical channel, simultaneously with E-DPCCH and E-DPDCH. For this reason, there is a problem that when the reception power of the DPCCH from another terminal is large, interference occurs and reception quality of each channel is deteriorated.

  The present invention has been made in view of the above, and an object of the present invention is to obtain a radio base station apparatus that performs E-DPDCH decoding using a selected E-DPCCH when retransmission data is received. .

  In order to solve the above-described problems and achieve the object, the present invention is a radio base station apparatus which receives code-multiplexed uplink data and performs retransmission control of data using HARQ. A reception signal storage means for storing a signal before despreading of the E-DPDCH in which the reception process has failed, and a demodulation process for the E-DPDCH signal when it is determined that the E-DPDCH reception process including the transmission fails The E-DPCCH decoding result at the time of initial transmission and all the E-DPCCH decoding results at the time of retransmission, the optimal E-DPCCH decoding result is based on the channel quality information at the time of receiving each E-DPCCH. All E-Ds at the time of initial transmission and retransmission using E-DPCCH selection means to be selected and control information consistent with the E-DPCCH decoding result selected by the E-DPCCH selection means Demodulation processing of DCH signal, characterized in that it comprises the E-DPDCH decoding means for performing a HARQ combining, and decoding processing, the.

  According to the present invention, there is an increased possibility that the E-DPDCH can be normally decoded and the transmission efficiency can be improved.

FIG. 1 is a diagram illustrating a configuration example of a conventional radio base station apparatus. FIG. 2 is a diagram illustrating a configuration example of a radio base station apparatus according to the present embodiment. FIG. 3 is a diagram illustrating a configuration example of a radio base station apparatus according to the present embodiment. FIG. 4 is a flowchart showing a reception process at the time of initial transmission. FIG. 5 is a flowchart showing reception processing at the time of retransmission.

  Embodiments of a radio base station apparatus according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment.
First, a conventional reception process performed by an EUL-compliant radio base station apparatus will be briefly described. FIG. 1 is a diagram illustrating a configuration example of a conventional radio base station apparatus. Here, after the signal received by the antenna is down-converted and converted to a digital signal by an A / D (Analogue / Digital) converter, until the E-DPDCH decoding is completed and before the data is passed to the upper layer The process of is shown.

  In the radio base station apparatus 100 shown in FIG. 1, the A / D conversion unit 11 converts the received analog signal into a digital signal and outputs the digital signal (F11). The E-DPCCH demodulation / decoding unit 12 performs demodulation processing and decoding processing including despreading and phase compensation on the digital signal, and extracts E-TFCI and RSN. Thereafter, the E-DPDCH demodulation unit 14 extracts the reception signal cached in the reception signal storage unit 13 (F13), despreads using the control information included in the output (F12) of the E-DPCCH demodulation decoding unit 12, Demodulation processing including processing such as phase compensation is performed. The E-DPDCH demodulation unit 14 sends the demodulated data to the HARQ combining unit 16 (F14), and sends the data to the demodulation result storage unit 15 that functions as a HARQ buffer (F15). The HARQ synthesizing unit 16 extracts the data to be synthesized from the received data (F14) if it exists in the demodulation result storage unit 15 (F16), and performs HARQ synthesis processing. The HARQ combining unit 16 sends the combined data to the decoded CRC determining unit 17 (F17). The decoding CRC determination unit 17 performs E-DPDCH decoding processing and CRC determination, outputs data determined to be normal by the CRC determination, and sends the data to the higher layer processing (F18).

  Note that the E-DPCCH demodulation / decoding unit 12 checks the consistency with the previous data after the initial transmission at the time of retransmission, and if the RSN becomes inconsistent, the demodulation result is a signal (F19) instructing buffer flush. The data is sent to the storage unit 15. Thereby, buffer flush is performed in the demodulation result storage unit 15.

  Next, reception processing by the radio base station apparatus in the present embodiment will be described. FIG. 2 is a diagram illustrating a configuration example of a radio base station apparatus according to the present embodiment. The radio base station apparatus 10 includes an A / D conversion unit 1, an E-DPCCH demodulation / decoding unit 2, an E-DPCCH selection unit 3, a received signal storage unit 4, an E-DPDCH demodulation unit 5, and a HARQ combining unit. 6 and a decoding CRC determination unit 7.

  The A / D converter 1 converts the analog signal received by the radio base station apparatus 10 into a digital signal. The E-DPCCH demodulation / decoding unit 2 performs E-DPCCH demodulation processing and decoding processing including despreading and phase compensation on the converted digital signal. The E-DPCCH selection unit 3 selects an E-DPCCH to be used for E-DPDCH demodulation when data is retransmitted. The reception signal storage unit 4 is a storage unit for storing a reception signal after digital conversion. The E-DPDCH demodulation unit 5 uses the received signal stored in the received signal storage unit 4 and the E-DPCCH control information selected by the E-DPCCH selection unit 3 to perform despreading, phase compensation, etc. E-DPDCH demodulation processing including processing is performed. The HARQ combining unit 6 performs HARQ combining processing on the received data. The decoded CRC determination unit 7 decodes the data after the HARQ combining process and performs CRC determination.

  In the radio base station apparatus 10, the A / D conversion unit 1 converts the received analog signal into a digital signal and outputs the digital signal (F01). The E-DPCCH demodulation / decoding unit 2 performs, on the digital signal, demodulation processing including despreading of E-DPCCH, phase compensation, and decoding processing for extracting control data including E-TFCI and RSN, A consistency check with the previous E-DPCCH decoding result is performed. The E-DPCCH demodulation / decoding unit 2 sends the check result of the consistency with the control data to the E-DPCCH selection unit 3 (F02). The E-DPCCH selection unit 3 selects a more reliable E-DPCCH when the E-DPCCH decoding result is inconsistent between the initial transmission and the retransmission, and sets a control signal value that matches the selected E-DPCCH. Generate and notify the E-DPDCH demodulator 5 (F03).

  As a reference for selection in the E-DPCCH selection unit 3, for example, the quality is best with reference to reception power of the E-DPCCH when each E-DPCCH is received, or SIR (Signal to Interference Ratio), etc. There are methods to select what is judged, but this is not a limitation. For example, it is possible to use interference power or estimated desired wave power, and it is also possible to use a function having these as elements. In addition, when the RSN at the time of initial transmission is 0 and the RSN at the time of retransmission is 2 instead of the originally expected 1, when the SIR at the time of retransmission is small and the reliability is low, this is not 1 but originally expected 1 As described above, HARQ is continued and buffer flush is not performed. If the E-TFCI at the time of retransmission is different from that at the time of initial transmission, the E-TFCI at the time of transmission with the larger SIR (at the time of initial transmission or retransmission) shall be the E-TFCI at the time of initial transmission and retransmission Can do.

  Next, a selection method when the number of retransmissions is many will be described. In the (N-1) th retransmission after the retransmission is repeated, for example, when the value b is selected as the E-TFCI value, the value b and the channel quality value p such as the SIR that has been selected are recorded, and N In the second retransmission, a value of c is received by E-TFCI, and if the channel quality value at that time is q, a selection method of selecting c if q is larger than p, and selecting b otherwise. Conceivable. By selecting in this way, when the E-DPCCH is inconsistent in each retransmission, the E-DPCCH at the time of the retransmission can always be determined with two choices.

  In addition, when retransmission is repeated and reception is performed three times or more, a selection method that takes a majority decision of each E-DPCCH decoding result may be adopted. For example, when the E-TFCI takes values of 0, 1, 0 in the order of the first transmission, the second time, and the third time, it is regarded as 0 and the data for these three times are demodulated and combined. However, since it is not possible to take a majority vote if the reception is three or more times and all are different E-TFCIs, the configuration can be selected by switching to the above-mentioned method based on the line quality. You may take

  In radio base station apparatus 10 according to the present embodiment, E-DPCCH selection unit 3 outputs a buffer flush instruction signal (F04). This is because when the RSN is inconsistent, the buffer flush is not performed immediately, the above selection process is attempted, and the buffer flush is performed only when the SIR as a selection index is small and cannot be trusted. This is to enable the operation method.

  The reception signal storage unit 4 serving as a HARQ buffer registers the signal (F01) after A / D conversion in a state before despreading. Note that the signal value stored in the reception signal storage unit 4 may be flashed under various conditions other than the buffer flash designation signal (F04). For example, when the E-DPCCH has not been detected more than a certain number of times as defined in the standard, the data is successfully decoded normally, and a memory that can be used for decoding the next data is secured. In some cases, it is reasonable to flush the internal data.

  The reception signal storage unit 4 stores a signal at the time of retransmission from the initial transmission until the next retransmission data is received and a new signal is registered, and a new signal is registered to the E-DPDCH demodulation unit 5. All past signals including the signal are passed (F05). The E-DPDCH demodulation unit 5 determines a despreading code based on the control signal (F03) output from the E-DPCCH selection unit 3, and despreads and phase compensates the data received from the received signal storage unit 4. And the result is sent to the HARQ synthesis unit 6 (F06). The HARQ combining unit 6 performs HARQ combining and sends the combined data to the decoded CRC determining unit 7 (F07). The decoding CRC determination unit 7 performs a decoding process of E-DPDCH data and a CRC determination. The decoded CRC determination unit 7 outputs data determined to be normal by the CRC determination, and sends the data to a higher layer process (F08). The processing after HARQ combining is the same as that of the conventional radio base station apparatus 100 shown in FIG.

  Thus, at the time of initial transmission and each retransmission, a more probable E-DPCCH is selected from the decoded E-DPCCH and the latest E-DPCCH decoding result based on criteria such as SIR, and data before despreading is selected. Re-demodulate from the start. For example, if the E-TFCI at the first transmission is 1 and the retransmission time is 2, and if the SIR at the time of retransmission is higher than that at the time of retransmission, the E-TFCI at the time of the initial transmission is assumed to be 2, and so on. Redo processing from spreading. Thereby, the error of E-DPCCH at the time of initial transmission can be detected, and the quality degradation of the HARQ combining result can be suppressed. In addition, the probability of completing decoding without increasing the number of retransmissions increases, and transmission efficiency improves.

  Although despreading is performed again each time retransmission data is received, the present invention is not limited to this. For example, when the reliability of the E-DPCCH is high, such as when the SIR is sufficient, the same HARQ buffer after despreading and demodulating may be used together so that the same demodulation processing is not repeated.

  Next, a method for improving the reception quality of received data will be described. FIG. 3 is a diagram illustrating a configuration example of a radio base station apparatus according to the present embodiment. The radio base station apparatus 10a includes an A / D conversion unit 1, an E-DPCCH demodulation / decoding unit 2, an E-DPCCH selection unit 3, a received signal storage unit 4a, an E-DPDCH demodulation unit 5, and a HARQ combining unit. 6, a decoding CRC determination unit 7, and a DPCCH decoding replica generation unit 8. The DPCCH decoding replica generation unit 8 decodes the DPCCH and generates a DPCCH replica from the channel measurement result. The reception signal storage unit 4a stores reception data obtained by subtracting the replica component received from the DPCCH decoding replica generation unit 8 from the corresponding reception data. In the radio base station apparatus 10a, the DPCCH decoding replica generation unit 8 and the reception signal storage unit 4a perform processing for canceling the uplink DPCCH from other terminals from the reception signal.

  In the radio base station apparatus 10a, the DPCCH decoding replica generation unit 8 processes and decodes signals from each terminal in the area, but the DPCCH decoding process is the same as the conventional one. The DPCCH decoding replica generation unit 8 generates a DPCCH replica from the decoding result and the channel measurement result, and passes the replica to the reception signal storage unit 4a so as to subtract the replica component from the corresponding reception data (F09). The reception signal storage unit 4a stores data obtained by subtracting the replica component from the reception data. Thereby, in the demodulation process after the E-DPDCH demodulator 5, demodulation is performed based on data from which the DPCCH that is an interference component is removed, so that reception quality can be improved. Other processes are the same as those of the radio base station apparatus 10. The received signal storage unit 4a stores the replica component by subtracting it from the corresponding received data. However, the present invention is not limited to this, and the subtraction process may be performed in another configuration. It may be performed by the E-DPDCH demodulation unit 5.

  Here, reception processing at the time of initial transmission and retransmission of the radio base station apparatus 10a will be described based on a flowchart. FIG. 4 is a flowchart showing a reception process at the time of initial transmission. In the radio base station apparatus 10a that has received the initial transmission signal (step S1), the A / D conversion unit 1 performs A / D conversion (step S2), and the E-DPCCH demodulation / decoding unit 2 demodulates and decodes the E-DPCCH. Is performed (step S3). Based on this result, the E-DPDCH demodulation unit 5 demodulates the E-DPDCH (step S4), and the decoding CRC determination unit 7 decodes (step S5). Further, the decoding CRC determination unit 7 performs CRC determination on the obtained bit sequence (step S6), and when it is OK (reception is successful) (step S6: OK), the reception is completed to the upper layer. The process for transferring the data and replying the ACK signal is performed (step S7). When the CRC judgment is NG (reception failure) (step S6: NG), the DPCCH decoding replica generation unit 8 performs DPCCH replica generation processing (step S8), and the reception signal storage unit 4a receives the received data from the received data. DPCCH cancellation, which is a subtraction process, is performed (step S9). The received signal storage unit 4a functioning as a HARQ buffer saves the received signal (step S10), and also saves the E-DPCCH so that consistency can be checked in the processes after retransmission (step S11). .

  FIG. 5 is a flowchart showing reception processing at the time of retransmission. The processes up to E-DPCCH demodulation and decoding (step S3) are the same as in the initial transmission. The E-DPCCH selection unit 3 determines the consistency between the decoding result of the E-DPCCH and the value at the previous reception (step S21), and when there is a mismatch (step S21: NG), selects the E-DPCCH. Processing is performed (step S22). At this time, the E-DPCCH selection unit 3 selects consistent E-TFCI and RSN that can be combined with HARQ. Using this result, the E-DPDCH demodulation unit 5 performs E-DPDCH demodulation processing including despreading of all retransmission signals from the initial transmission stored in the reception signal storage unit 4a to step S23 (step S23). ). Thereafter, the HARQ combining unit 6 performs HARQ combining of the demodulated data (step S24), and the decoding CRC determination unit 7 performs processing in the order of E-DPDCH decoding (step S5) and CRC determination (step S6). Do. The subsequent processing is the same as the initial transmission processing shown in FIG. If the decoding result of E-DPCCH matches the value at the previous reception (step S21: OK), E-DPDCH demodulation processing is performed without selecting E-DPCCH (step S23).

  Note that in the flowchart at the time of retransmission (FIG. 5), the DPCCH cancellation processing (steps S8 to S9) of the received data at the time of retransmission is omitted, but may be performed in the same manner as at the time of initial transmission (FIG. 4). In addition, the timing of DPCCH cancellation at the time of initial transmission (FIG. 4) is after CRC NG determination, but is not limited to this, and may be performed before each decoding process shown in the figure. Although the accuracy of the decoding result can be expected to be improved by performing the DPCCH cancellation first, it may be canceled even for data of sufficient quality that originally does not need to be canceled, and it is expected that the waste will increase. Therefore, at the time of initial transmission (FIG. 4), DPCCH cancellation is performed after CRC NG (step S6: NG).

  In addition, although the radio base station apparatus 10a has been described, it is applicable to the radio base station apparatus 10 by deleting the DPCCH cancellation process in steps S8 to S9.

  As described above, according to the present embodiment, when an E-DPCCH mismatch is detected at the time of data retransmission, a reliable E-DPCCH is selected based on the SIR of the data at the time of each transmission, and the selected E-DPCCH is selected. Based on the control information decoded from the E-DPCCH, the E-DPDCH is decoded for each retransmission. Thereby, possibility that E-DPDCH can be decoded normally will become high and transmission efficiency can be improved. In addition, when a new E-DPCCH is selected, the E-DPDCH is demodulated again from the initial transmission based on control information decoded from the newly selected E-DPCCH. As a result, since there is no data decoded using erroneous E-TFCI, it is possible to obtain the expected reception quality improvement effect during HARQ combining.

  Also, after the E-DPDCH and E-DPDCH, a DPCCH replica that is received at the same time is created, and the processing after the E-DPDCH demodulation is performed based on the data from which the interference component is removed by subtracting the replica component from the corresponding received data Therefore, the reception quality can be improved.

  In addition, when there is an equivalent selection candidate in the processing when the inconsistency is detected in the E-DPCCH selection unit 3, when the data decoded by selecting one is determined as reception failure by the CRC determination It is also possible to select the other and try the demodulation and decoding process again. For example, it is effective when the channel quality values of the E-DPCCHs that are selection candidates are equal. In this case, by trying decoding using both, the probability of successful decoding while suppressing the number of retransmissions is improved.

  In addition, since the data before despreading is stored in the reception signal storage unit 4 serving as a HARQ buffer, the amount of memory used tends to increase. In order to suppress this, the received signal storage unit 4 may be configured to store a cumulative value of received values. This makes it impossible to extract individual received values each time, but when performing HARQ by Chase combining that transmits and receives the same data in each retransmission, it is possible to perform a decoding process using accumulated values. .

  As described above, the radio base station apparatus according to the present invention is useful for an EUL-compliant radio base station apparatus, and is particularly suitable for a radio base station apparatus that performs retransmission control using HARQ.

DESCRIPTION OF SYMBOLS 1 A / D conversion part 2 E-DPCCH demodulation decoding part 3 E-DPCCH selection part 4, 4a Reception signal memory | storage part 5 E-DPDCH demodulation part 6 HARQ synthetic | combination part 7 Decoding CRC judgment part 8 DPCCH decoding replica production | generation part 10, 10a Wireless base station equipment

Claims (6)

A radio base station apparatus that receives code-multiplexed uplink data and performs retransmission control of data using HARQ,
A reception signal storage means for storing a signal before despreading of the E-DPDCH in which the reception process has failed when the E-DPDCH reception process including the data body fails and it is determined to perform retransmission;
When performing E-DPDCH signal demodulation processing, it is optimal based on channel quality information at the time of receiving each E-DPCCH from among the E-DPCCH decoding results at the time of initial transmission and all E-DPCCH decoding results at the time of retransmission. E-DPCCH selection means for selecting a result of the E-DPCCH decoding,
E that performs demodulation processing, HARQ combining, and decoding processing of all E-DPDCH signals at the time of initial transmission and retransmission using control information that matches the E-DPCCH decoding result selected by the E-DPCCH selection means -DPDCH decoding means;
A radio base station apparatus comprising: The line quality information is at least one of a received power value, an estimated desired wave power value, and an interference power value,
The radio base station apparatus according to claim 1. The E-DPCCH selection means selects, based on the majority of each control information value of the E-DPCCH decoding result, without using the channel quality information when the number of receptions of E-DPCCH including initial transmission is 3 times or more. To
The radio base station apparatus according to claim 1. There are a plurality of E-DPCCH decoding results, and the E-DPDCH decoding means uses the control information value matched with the E-DPCCH decoding result initially selected by the E-DPCCH selection means to demodulate the E-DPDCH signal. When it is determined that reception has failed as a result of performing HARQ combining and decoding processing,
The E-DPCCH selection means newly selects a different E-DPCCH decoding result,
The E-DPDCH decoding means performs E-DPDCH signal demodulation processing, HARQ combining, and decoding processing based on control information matched with a newly selected E-DPCCH decoding result.
The radio base station apparatus according to claim 1, 2, or 3. The received signal storage means accumulates and stores signals before despreading of E-DPDCH that has failed to be received,
The radio base station apparatus according to any one of claims 1 to 4. further,
DPCCH decoding replica creation means for creating a DPCCH replica from the received DPCCH decoding result and channel estimation result;
With
The received signal storage means stores an E-DPDCH signal obtained by subtracting the DPCCH replica component corresponding to the signal from the signal before despreading of the E-DPDCH that has failed to be received,
The E-DPDCH decoding means performs demodulation processing, HARQ combining, and decoding processing of the E-DPDCH signal after subtraction.
The radio base station apparatus according to any one of claims 1 to 5, wherein:

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