JP3697111B2 - Receiver - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a receiving apparatus, and more particularly to a receiving apparatus used for OFDM mobile communication and a synchronization acquisition method in a random access channel (hereinafter referred to as “RAch”) section.
[0002]
[Prior art]
In mobile communication, when a time division method such as TDMA or CDMA / TDD is used as an access method, an uplink (Up Link; hereinafter referred to as “UL”) and a downlink (Down Link; hereinafter referred to as “DL”) In order to use the same frequency, it is necessary to establish synchronization between base stations.
[0003]
This will be explained with reference to FIG. 3. The base station 301 indicated by BS1 in the figure establishes synchronization not only with the mobile station 302 within its own cell indicated by MS in the figure but also with the base station 303 indicated by BS2 in the figure. There is a need to.
[0004]
Here, FIG. 4A shows an example of a frame format of a transmission signal when the time division method is adopted. One frame includes DL 401, UL 402, and RAch 403, and each DL and each UL includes a plurality of channels.
[0005]
DL 401 is used for transmission from the base station to the mobile station, and UL 402 is used for transmission from the mobile station to the base station. Therefore, establishment of synchronization between base stations is performed using the RAch 403.
[0006]
However, the RAch 403 is not only used for establishing synchronization between base stations, but is also used randomly for communication with mobile stations. Therefore, the base station device needs to be able to receive signals from the mobile station and signals from other base stations in the RAch section.
[0007]
Here, FIG. 4B shows an example of the frame format of the transmission signal from the mobile station, and FIG. 4C shows an example of the frame format of the transmission signal from the base station. The transmission signal from the mobile station is composed of an MS synchronization symbol 404, a pilot symbol 405, and an effective symbol 406. The transmission signal from the base station is an BS synchronization symbol 407, a pilot symbol 408, and an effective symbol. 409. Here, the MS synchronization symbol 404 and the BS synchronization symbol 407 are different known signals, the pilot symbol is used for phase rotation detection, and the effective symbol is a symbol including transmission data.
[0008]
Therefore, the conventional base station apparatus has two reception processing systems, and establishes synchronization using different known signals, thereby allowing random reception of a signal from the mobile station and a signal from the base station in RAch. Realized.
[0009]
Hereinafter, a receiving apparatus used in a conventional base station apparatus will be described with reference to FIGS. 5 and 6. FIG. 5 is a principal block diagram showing a schematic configuration of a conventional receiving apparatus, and FIG. 6 is a principal block diagram showing a schematic configuration of a synchronization acquisition section of the conventional receiving apparatus. Here, it is assumed that the number of branches is two.
[0010]
In FIG. 5, the antenna 501 that is the branch 1 and the antenna 502 that is the branch 2 receive the radio signal, and the reception processing unit 503 and the reception processing unit 504 receive the signals received by the antenna 501 and the antenna 502, respectively. To do.
[0011]
Synchronization acquisition sections 505 to 508 acquire synchronization from the correlation value between the received signal and the known signal, and output symbol synchronization timing. If synchronization is not acquired, symbol synchronization timing is not output. Here, the synchronization acquisition unit 505 detects synchronization using the BS synchronization symbol as a known signal with respect to the branch 1 reception signal, and similarly, the synchronization acquisition unit 506 receives the branch 2 reception signal. Using the BS synchronization symbol, the synchronization acquisition unit 507 uses the MS synchronization symbol for the branch 1 reception signal, and the synchronization acquisition unit 508 uses the MS synchronization symbol for the branch 2 reception signal, Each detects synchronization. The configuration within each synchronization acquisition unit will be described later.
[0012]
The FFT processing unit 509 performs FFT processing on the received signal of the branch 1 using the symbol synchronization timing acquired by the synchronization acquisition unit 505 as the processing start timing. Similarly, the FFT processing unit 510 includes the synchronization acquisition unit 506. The FFT processing unit 511 performs FFT processing on the received signal of the branch 2 using the symbol synchronization timing acquired by the processing as the processing start timing, and the FFT processing unit 511 uses the symbol synchronization timing acquired by the synchronization acquisition unit 507 as the processing start timing. The FFT processing unit 512 performs FFT processing on the received signal of branch 2 using the symbol synchronization timing acquired by the synchronization acquisition unit 508 as the processing start timing.
[0013]
Demodulation section 513 performs demodulation processing, error detection, and error correction processing on the received signal subjected to FFT processing by FFT processing section 509 and FFT processing section 510, and data transmitted from other base stations (BS data) Is output. Demodulation section 514 performs demodulation processing, error detection, and error correction processing on the received signal subjected to FFT processing by FFT processing section 511 and FFT processing section 512, and outputs data (MS data) transmitted from the mobile station To do.
[0014]
If synchronization is not acquired, neither FFT processing nor demodulation processing is performed.
[0015]
Next, the configuration of the synchronization acquisition units 505 to 508 will be described with reference to FIG. In FIG. 6, a correlator 601 correlates the input received signal of branch 1 or the received signal of branch 2 with a known signal. Here, the known signal is a signal obtained by performing IFFT processing on a synchronization symbol for BS or IFFT processing on a synchronization symbol for MS.
[0016]
The absolute value detection unit 602 detects the absolute value of the correlation result, and the determination unit 603 integrates the absolute value of the correlation result, and determines whether or not the integrated value exceeds an arbitrary threshold value. If the integrated value exceeds the threshold value, it is determined that synchronization has been established. If the integrated value does not exceed the threshold value, it is determined that synchronization has not been established.
[0017]
Maximum value detection section 604 detects the timing at which the accumulated correlation value takes the maximum value, and timing generation section 605 sets the detected timing as the symbol synchronization timing.
[0018]
Note that the FFT processing start timing is not limited to being performed independently for each branch as described above, but is also a method using the timing that is established at the forefront among all branches, or a timing that averages the timings of all branches. There has also been proposed a method for using.
[0019]
As described above, the receiving apparatus in the conventional base station apparatus has two receiving systems and acquires synchronization using different known signals. Therefore, in RAch, transmission signals from other base stations and mobile stations receive signals. Both transmission signals can be received at random.
[0020]
[Problems to be solved by the invention]
However, since the conventional receiving apparatus has two reception processing systems, there is a problem that the hardware scale increases.
[0021]
The present invention has been made in view of this point, and an object of the present invention is to provide a receiving apparatus with a reduced hardware scale and a synchronization acquisition method in the RAch section.
[0022]
[Means for Solving the Problems]
In the present invention , in the RAch period , synchronization is acquired using different known signals for each branch, and the symbol synchronization timing in the branch where synchronization is established is used as the symbol synchronization timing in the reception signals of all branches .
[0023]
DETAILED DESCRIPTION OF THE INVENTION
The receiving apparatus according to the first aspect of the present invention integrates a correlation unit between a receiving unit that receives OFDM signals in a plurality of branches, a received signal of each branch, and a known signal that is different for each branch that is held in advance. A branch whose value exceeds an arbitrary threshold is a synchronization acquisition determination means for determining that synchronization has been established, and the integrated value for the branch for which synchronization is determined to be established by the synchronization acquisition determination means. And a synchronization timing setting means for setting the timing for taking the maximum value as the symbol synchronization timing in all branches.
[0024]
According to this configuration, different synchronization symbols are obtained by acquiring synchronization using different known signals for each branch and using the symbol synchronization timing in the branch where synchronization is established as the symbol synchronization timing in the reception signals of all branches. Since it is possible to receive in one reception processing system even in a time zone in which it is unclear from which of the plurality of transmitting stations using the base station, the hardware scale of the base station apparatus can be reduced.
[0025]
A base station apparatus according to a second aspect of the present invention includes the receiving apparatus according to the first aspect, wherein the known signal includes a synchronization symbol added to transmission data by a mobile station and a base station adds to transmission data. And a synchronization symbol.
[0026]
The base station apparatus according to a third aspect of the present invention is the base station apparatus according to the second aspect, wherein in the time zone in which only the mobile station communicates, all the known signals that take correlation values with the received signals of each branch are As a synchronization symbol to be added to the transmission data, the mobile station adds it to the transmission data as the known signal that takes a correlation value with the received signal of each branch in the time zone in which the mobile station and other base stations communicate randomly. In this configuration, a synchronization symbol to be used and a synchronization symbol to be added to transmission data by the base station are employed.
[0027]
According to these configurations, synchronization is obtained using different known signals for each branch, and the symbol synchronization timing in the branch where synchronization is established is used as the symbol synchronization timing in the reception signals of all branches, thereby allowing one reception process. Also in the system, signals from the mobile station and other base stations can be received randomly in the RAch section, so that the hardware scale of the base station apparatus can be reduced.
[0028]
The communication terminal apparatus according to the fourth aspect of the present invention employs a configuration for performing wireless communication with the base station apparatus according to the second aspect or the third aspect.
[0029]
According to this configuration, by using different synchronization symbols in the mobile station and the base station, the base station as a receiving station can receive signals from the mobile station and other base stations randomly in the RAch section. The hardware scale of the base station apparatus can be reduced.
[0030]
The synchronization acquisition method according to the fifth aspect of the present invention is a method for receiving an OFDM signal in a plurality of branches and calculating a correlation value with a known signal in a time zone in which communication with a mobile station or another base station is performed randomly. The calculation is performed using a synchronization symbol added to the transmission data by the mobile station as a known signal for a predetermined branch, and using a synchronization symbol added to the transmission data by the base station as a known signal for another predetermined branch. The timing at which the integrated value at which the integrated value of correlation values exceeds an arbitrary threshold value takes the maximum value is set as the symbol synchronization timing for all branches.
[0031]
According to this method, synchronization is obtained by using different known signals for each branch, and the symbol synchronization timing in the branch where the synchronization is established is used as the symbol synchronization timing in the reception signals of all branches, so that one reception processing system Since the signals from the mobile station and other base stations can be received at random in the RAch section, the hardware scale of the base station apparatus can be reduced.
[0032]
Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. It is assumed that the number of branches is 2.
[0033]
Hereinafter, the receiving apparatus according to the present embodiment will be described with reference to FIG. 1 and FIG. FIG. 1 is a principal block diagram illustrating a schematic configuration of a receiving device according to an embodiment of the present invention, and FIG. 2 illustrates a schematic configuration of a selection unit of the receiving device according to an embodiment of the present invention. It is a principal part block diagram.
[0034]
In FIG. 1, the antenna 101 that is the branch 1 and the antenna 102 that is the branch 2 receive the radio signal, and the reception processing unit 103 and the reception processing unit 104 receive the signals received by the antenna 101 and the antenna 102, respectively. To do.
[0035]
Synchronization acquisition sections 105 to 106 acquire synchronization from the correlation value between the received signal and the known signal, and output symbol synchronization timing. Since the configuration of the synchronization acquisition unit is the same as the conventional one, a detailed description on the configuration is omitted.
[0036]
Here, the synchronization acquisition unit 105 detects synchronization using the MS synchronization symbol as a known signal with respect to the reception signal of the branch 1, and the synchronization acquisition unit 106 receives the branch 2 in the DL section and the UL section. Synchronization is detected using the MS synchronization symbol as a known signal for the signal, and synchronization is detected using the BS synchronization symbol for the received signal of branch 2 as the known signal in the RAch period.
[0037]
Based on the control signal, the selector 107 is switched so that the synchronization symbol for MS is input to the synchronization acquisition unit 106 in the DL interval and the UL interval, and the synchronization symbol for BS is synchronized with the synchronization acquisition unit 106 in the RAch interval. It is switched to be input to. The control signal is an instruction signal indicating which time zone is DL / UL / RAch. Since these time zones are assigned by the base station apparatus, the control signal is known.
[0038]
The selection unit 108 detects whether synchronization is acquired by the synchronization acquisition unit 105 or the synchronization acquisition unit 106 in the RAch period, and outputs it to the demodulation unit 111 as an identification signal, and the symbol synchronization of which synchronization has been acquired The timing is output to the FFT processing unit 109 and the FFT processing unit 110.
[0039]
The FFT processing unit 109 performs FFT processing on the received signal of branch 1 based on the symbol synchronization timing selected by the selection unit 108, and the FFT processing unit 110 is based on the symbol synchronization timing selected by the selection unit 108. Then, FFT processing is performed on the received signal of branch 2.
[0040]
The demodulation unit 111 performs demodulation processing, error detection, and error correction processing on the received signal subjected to the FFT processing by the FFT processing unit 109 and the FFT processing unit 110, and receives data transmitted from the mobile station or another base station. Output the transmitted data.
[0041]
Here, since the data length differs between the received signal from the mobile station and the received signal from another base station, the demodulating unit 111 changes the setting based on the identification signal output from the selecting unit 108 and then performs the demodulating process. Perform error detection and error correction processing.
Next, the configuration of the selection unit 108 will be described with reference to FIG. In FIG. 2, a counter 201 is a counter that is counted when synchronization is acquired by the synchronization acquisition unit 105, and a counter 202 is a counter that is counted when synchronization is acquired by the synchronization acquisition unit 106.
[0043]
The comparison unit 203 compares the count value of the counter 201 with the count value of the counter 202. If the count value of the counter 201 is larger, the comparison unit 203 determines that the received signal is a signal transmitted from the mobile station. If the count value of 202 is larger, it is determined that the received signal is a signal transmitted from another base station, and an identification signal indicating the determination result is output.
[0044]
Based on the identification signal output from the comparison unit 203, the selector 204 determines whether either the symbol synchronization timing detected by the synchronization acquisition unit 105 or the symbol synchronization timing detected by the synchronization acquisition unit 106 is FFT processing unit 109 and FFT processing. Switching to be input to the unit 110. That is, if it is a received signal from a mobile station, the timing detected about branch 1 is used, and if it is a received signal from another base station, the timing detected about branch 2 is used.
[0045]
Next, the operation of the receiving apparatus according to this embodiment will be described.
[0046]
The OFDM signal is received by the antenna 101 and the antenna 102 and received by the reception processing unit 103 and the reception processing unit 104.
[0047]
In the DL section and the UL section in which the base station and the mobile station are communicating, the MS synchronization symbol is input to the synchronization acquisition unit 106, that is, the synchronization detection is performed using the MS synchronization symbol in all synchronization acquisition units. Is done.
[0048]
In the RAch period in which it is not determined which signal from the other base station or the signal from the mobile station is received, the BS synchronization symbol is input to the synchronization acquisition unit 106, that is, a known signal that differs between branch 1 and branch 2 Is used to detect synchronization.
[0049]
The counter provided in the branch where the synchronization is acquired is counted, and the counter provided in the branch where the synchronization is not acquired remains 0, so that the branch where the synchronization is acquired is detected by the comparison unit 203. The
[0050]
The symbol synchronization timing detected for the branch from which synchronization is acquired is set by the selection unit 108 as processing start timings of the FFT processing unit 109 and the FFT processing unit 110.
[0051]
The received signal subjected to the reception processing is subjected to FFT processing by the FFT processing unit 109 and the FFT processing unit 110, and subjected to demodulation processing, error detection, and error correction processing by the demodulation unit 111, and transmitted from another base station. Data or data transmitted from the mobile station is obtained.
[0052]
As described above, according to the present embodiment, synchronization is acquired using different known signals for each branch, and the symbol synchronization timing in the branch where synchronization is established is used as the symbol synchronization timing in the reception signals of all branches. Also, even in one reception processing system, signals from the mobile station and other base stations can be received randomly in the RAch section, so that the hardware scale of the base station apparatus can be reduced.
[0053]
Also in the present embodiment, the frame format is not limited to the example shown in FIG. 4 and may include an AGC symbol and a guard interval.
[0054]
【The invention's effect】
As described above, according to the present invention, synchronization is obtained by using different known signals for each branch, and the symbol synchronization timing in the branch where synchronization is established is used as the symbol synchronization timing in the reception signals of all branches. Also, even in one reception processing system, signals from the mobile station and other base stations can be received randomly in the RAch section, so that the hardware scale of the base station apparatus can be reduced.
[Brief description of the drawings]
FIG. 1 is a principal block diagram illustrating a schematic configuration of a receiving apparatus according to an embodiment of the present invention. FIG. 2 is a principal block diagram illustrating a schematic configuration of a selection unit of the receiving apparatus according to an embodiment of the present invention. FIG. 3 is a schematic diagram for explaining establishment of synchronization between base stations. FIG. 4A is a schematic diagram showing an example of a frame format of a transmission signal when a time division method is adopted. FIG. 3B is a transmission signal from a mobile station. (C) Schematic diagram showing an example of a frame format of a transmission signal from a base station FIG. 5 is a principal block diagram showing a schematic configuration of a conventional receiving apparatus. Main block diagram showing the schematic configuration of the synchronization acquisition unit of the receiver [description of the code]
107 selector 108 selector

Claims (4)

Receiving means for receiving radio signals in a plurality of branches;
Detecting means for detecting symbol synchronization timing for each branch ;
Setting means for setting the symbol synchronization timing detected in the branch having the largest number of detected symbol synchronization timings as the symbol synchronization timing for all of the plurality of branches ;
A receiving apparatus comprising: Comprising the receiving device according to claim 1;
The detection means includes
The symbol synchronization timing is detected based on the correlation value between the received signal and the known signal,
At the time of communication only with the mobile station, the first synchronization symbol added to the transmission data by the mobile station is used as a known signal in all branches,
At the time of communication with the mobile station or another base station , the first synchronization symbol is used as a known signal in a predetermined branch, and the other base station transmits the transmitted data as a known signal in another branch. Using a second synchronization symbol to be added,
A base station apparatus. A mobile station apparatus that performs wireless communication with the base station apparatus according to claim 2 . In a time when communicating with a mobile station or a base station , when a radio signal is received by a plurality of branches and synchronization is acquired based on a correlation value between the received signal and a known signal , the predetermined branch is used as a known signal. , using a synchronization signal which the mobile station is added to the transmission data, for the other branches, as a known signal, Ru using the synchronization signal from the base station is added to the transmission data,
A synchronization acquisition method characterized by the above.

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