JP2006067002A - Receiver and method for measuring desired-to-interference power ratio - Google Patents

Abstract

PROBLEM TO BE SOLVED: To use a power value of a received signal for each antenna when communication can be established if phase control is appropriately performed even in an initial state where control of an antenna on a transmitting side is not properly performed. The desired wave-to-interference wave power ratio can be calculated to correctly determine synchronization.
A demodulator 200 demodulates symbols transmitted from two antennas and outputs two demodulated symbols, and squaring units 321a and 321b square each of the two demodulated symbols to obtain two power values. The adder 322 calculates the desired wave power by adding the two power values, the ISCP calculator 330 calculates the interference wave power from the two demodulated symbols, and the SIR calculator 340 The desired wave-to-interference wave power ratio is calculated by subtracting the interference wave power from the wave power.
[Selection] Figure 1

Description

  The present invention relates to a receiver and a method for measuring a desired wave-to-interference wave power ratio, and more particularly, to a receiver and a method for measuring a desired wave-to-interference wave power ratio in transmission diversity.

  For example, 3GPP (3rd Generation Partnership project) is used in a communication system to which transmission power control using a signal to interference ratio (SIR) and transmission diversity for controlling a transmission antenna is applied. This includes a CDMA (Code Division Multiple Access) system in which standardization activities are performed.

  Transmission diversity will be described by taking transmission diversity defined by 3GPP as an example. In the W-CDMA (Wide Band CDMA) system, which is standardized in 3GPP, there are three types of transmission diversity methods: STTD (Space Time Transmit Diversity), CL1 (Closed Loop Mode1), and CL2 (Closed Loop Mode2). The method is defined in TS25.214, which is a 3GPP specification.

  For example, in transmission diversity CL1, control is performed so that the combined vector of transmission signals transmitted from two antennas arranged in the base station is maximized at the receiver receiving antenna end. The receiver transmits an uplink command, and the base station controls the phase of a desired channel of one antenna according to the transmitted uplink command. Examples of the desired channel include DPCH (Dedicated Pilot Channel) and HSPSCH (High Speed Physical Downlink Shared Channel). At this time, CPICH (Common Pilot Channel) symbols transmitted simultaneously with data and pilot symbols included in DPCH are encoded and transmitted so as to be orthogonal between antennas. Therefore, the receiver can perform demodulation by separating the received symbols for each antenna.

  In the CDMA system, for the purpose of increasing the system capacity, base station transmission power control (downlink transmission power control) is performed so that the reception quality of the receiver always matches the target quality. This downlink transmission power control is performed based on the result of comparing the target quality at the receiver and the SIR measured at the receiver. Therefore, the receiver needs to measure the SIR. Further, SIR is an index representing reception quality. For this reason, it is generally used for synchronization determination as well as for the purpose of maintaining the reception quality of the receiver. Here, the synchronization determination means that synchronization is established (synchronization established) when the reception quality is above a certain level, and that synchronization is not established (synchronization is not established) when the reception quality is below a certain level. Is.

Here, a conventional SIR measurement method will be described using, for example, a measurement apparatus disclosed in Patent Document 1. In Patent Document 1, an inverse modulator to which a demodulation symbol is input from a detector or the like, an averager that receives one output (demodulation symbol) of the inverse modulator, and another output (demodulation symbol) of the inverse modulator, A dispersion calculator that receives one output of the averager, a squarer that receives the other output of the averager, a time averager that receives the output of the dispersion calculator, and a squarer A RSCP (Received Signal Code Power) value and an ISCP value (Interference Signal Code Power) output from the time averager, and a comparator that outputs an SIR value to the outside. An SIR measuring apparatus is disclosed.
Japanese Patent Laid-Open No. 10-135904

  However, the SIR measurement device disclosed in Patent Document 1 does not consider reception signals transmitted from a plurality of antennas arranged in a base station. In particular, in the initial state where the control of multiple antennas is not performed, for example, in the initial state in a closed loop of transmission diversity, transmission can be performed from multiple antennas when communication can be established if phase control is performed correctly. SIR reflecting the power value of each received signal cannot be measured. Therefore, there is a problem that synchronization is not established even when synchronization is established if the phase control of the antenna is performed.

  The present invention has been made in view of such a point, and even in an initial state where the phase control of the antenna on the transmitting side is not correctly performed, communication can be established if the phase control is appropriately performed. Another object of the present invention is to provide a receiver or a method for measuring a desired wave-to-interference wave power ratio that can increase the desired-wave-to-interference wave power ratio and establish synchronization.

  The receiver of the present invention comprises a demodulating means for demodulating symbols transmitted from two antennas and outputting two demodulated symbols, a squaring means for calculating a power value of each of the two demodulated symbols, and the two An adding means for calculating a desired wave power by adding power values, an interference wave power calculating means for calculating an interference wave power from the two demodulated symbols, and a desired wave by dividing the desired wave power by the interference wave power. A desired wave-to-interference wave power ratio calculation unit that calculates an interference-wave power ratio is employed.

  According to the present invention, even in an initial state where the phase control of the antenna on the transmitting side is not performed, the communication power can be established if the phase control is appropriately performed. Can be increased and synchronization can be established. In particular, when transmission diversity for controlling the antenna on the transmitting side is applied, and even in an initial state where control of the transmission antenna is not performed correctly, communication establishment is possible if phase control is performed appropriately. The desired signal-to-interference power ratio can be increased so as to establish synchronization determination.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In this specification, “symbol” includes at least one of a pilot symbol and a data symbol, or both unless otherwise specified.

(Embodiment 1)
1 is a block diagram showing an example of the configuration of a receiver according to Embodiment 1 of the present invention. In the present embodiment, a case of transmission diversity implemented in a closed loop mode will be described. The receiver receives reception signals transmitted from two antennas arranged in the base station. In addition, signals transmitted from each of the two antennas arranged in the base station are weighted, combined, and received by the receiver. Hereinafter, the two antennas are referred to as an antenna 1 and an antenna 2.

  The receiver includes a decoding unit 100, a demodulation unit 200, a SIR measurement device (desired wave-to-interference wave power ratio measurement device) 300, and a synchronization determination unit 400. The SIR measurement apparatus 300 includes an average calculation unit 310, an RSCP calculation unit (desired wave power calculation unit) 320, an ISCP calculation unit (interference wave power calculation unit) 330, and an SIR calculation unit (desired wave interference wave power ratio calculation unit). 340. The average calculation unit 310 includes averaging units 311a and 311b, and the RSCP calculation unit 320 includes squaring units 321a and 321b and an addition unit 322.

  Decoding section 100 receives a received signal, separates the received signal received for each antenna, and extracts pilot symbols. Specific examples of the extracted pilot symbols include CPICH and DPCH pilot symbols.

  Demodulation section 200 removes the information modulation contained in the pilot symbols separated for each of the two antennas input from decoding section 100, and demodulates (inverts) the demodulation symbols.

  SIR measuring apparatus 300 receives a demodulated symbol from demodulating section 200, calculates an SIR using the demodulated symbol, and outputs the SIR to synchronization determining section 400.

  The average calculation unit 310 calculates and outputs an average value for each determined average section for the demodulated symbols for two antennas. The average interval is a predetermined time, and an averaging process is performed to calculate the average of symbols received in the average interval. Averagers 311a and 311b perform computations corresponding to the two demodulated symbols.

  The RSCP calculator 320 calculates the power value of each of the averaged demodulated symbols for each antenna, and then adds them to calculate the RSCP. Specifically, the calculation is performed by the following two components.

Each of the squaring units 321a and 321b calculates the power value of the symbol. In calculating the power value of the symbol, the demodulated symbol is squared to calculate the power value. Symbol squared means the sum of the square of the I component and the square of the Q component. Specifically, when the symbol-squared value is P, it can be expressed as P = I ² + Q ² . The power values calculated by the squaring units 321a and 321b are output to the adding unit 322.

  Adder 322 adds the power values for each antenna and outputs the result as RSCP.

  The ISCP calculator 330 calculates the ISCP from the demodulated symbol for each antenna. FIG. 2 is a block diagram illustrating an example of the configuration of the ISCP calculation unit 330. The ISCP calculation unit 330 includes a variance calculation unit 331, an addition unit 332, and a time averaging unit 333.

  The dispersion calculation units 331a and 331b calculate the dispersion for each antenna from the demodulation symbols for each antenna. The adder 332 adds the dispersion value for each antenna. The time averaging unit 333 performs time averaging processing on the added variance value and outputs the result as ISCP.

  The SIR calculation unit 340 calculates SIR by dividing ISCP from RSCP. The calculated SIR value is used by the synchronization determination unit 400 or the like.

  The synchronization determination unit 400 determines whether synchronization is established using the SIR calculated by the SIR measurement apparatus 300.

  Although not shown in FIG. 1, the receiver includes a CPU (Central Processing Unit) and controls each of the above components. Further, the receiver has a storage area, and stores (including temporarily stores) data such as input received signals, demodulated symbols, RSCP, ISCP, and SIR. In the averaging process, a plurality of data (time series data) is stored in the storage area, and the averaging process is performed.

  Next, the operation of the receiver having the above configuration will be described.

  The pilot symbols are encoded so as to be orthogonal and transmitted from the base station. For this reason, the decoding unit 100 performs a decoding process for separating the received signal from pilot symbols for each antenna of the base station. Demodulation section 200 removes the information modulation of the two pilot symbols separated for each antenna by decoding section 100 and outputs the two demodulated symbols to average calculation section 310 and ISCP calculation section 330, respectively.

  Average calculation section 310 averages and outputs each demodulated symbol for each antenna. In RSCP calculation section 320, squaring sections 321a and 321b calculate the power value of each demodulated symbol for each antenna, and then addition section 322 calculates the RSCP by adding the power values for each antenna. And output to the SIR measurement unit 340.

  In the ISCP calculation unit 330, the dispersion calculation units 331a and 331b calculate the dispersion value for each antenna from the demodulation symbol for each antenna, the addition unit 332 adds the dispersion value for each antenna, and the time averaging unit 333 The ISCP is calculated by performing time averaging processing on the added dispersion value, and is output to the SIR measurement unit 340.

  The SIR output unit 340 calculates SIR by dividing ISCP from RSCP.

  Next, the relationship between the RSCP calculated by the above operation and the received signal will be described. First, the configuration of the received signal will be described. FIG. 3 is a diagram showing a configuration of DPCH data symbols and pilot symbols. FIG. 3 shows an example in which symbols transmitted from two antennas of the base station are combined. At the time of transmission diversity CL1, in the base station, pilot symbols are encoded, but data symbols, for example, DPDCH (Dedicated Physical Data Channel), HSPDSCH, and the like are not encoded.

  FIG. 4 is a diagram showing the relationship between the power and the symbols transmitted from the two antennas in the receiver, and shows the reception status of the symbols using a vector indicating the received signal. In FIG. 4, received signal A is a received signal transmitted from antenna 1, received signal B is a received signal transmitted from antenna 2, and received signal C is received signal A and received signal transmitted from both antennas. This is a received signal synthesized by vector addition of B. A reception signal D indicates a reception signal of the antenna 1 and the antenna 2 when the phase of the antenna 1 is appropriately controlled. E is a threshold value indicating a power value that can be received by the receiver.

  At the time of transmission diversity CL1, in the initial state (before synchronization is established) before the phase control information from the receiver is transmitted, the base station receives signals from the two antennas in a state before the phase control of the antenna is correctly performed. Send. Therefore, the symbols of the two antennas can be in a phase that weakens the signal between the antennas. In FIG. 4, the reception signal obtained by combining the reception signal A and the reception signal B is a reception signal C. In this way, the received power at the receiver can be very small.

  The pilot symbols are encoded so as to be orthogonal between the antennas when transmitting to the base station, and the receiver receives the received pilot symbols from the received signal A transmitted from the antenna 1 and the received signal B transmitted from the antenna 2. Can be separated. On the other hand, the data symbol is not encoded, and an inter-antenna vector combined received signal that is a combined vector of both antennas is received as received signal C.

  Therefore, the RSCP calculation unit 320 of the present embodiment uses the pilot symbols separated for each antenna to calculate the power value for each antenna and adds the calculated power value. Therefore, even when the phase control is not performed at the base station as in the reception signal C of FIG. 4 and the power value of the reception signal of the receiver becomes small, the antenna is not affected by the phase control. The power value of each received signal can be measured. Furthermore, if a synchronization determination threshold for the power value of the received signal calculated in this way is set, communication can be established if the phase control of the base station is appropriately performed even when the phase control is not performed. In such a case, it can be determined that synchronization is established and communication can be established.

  As described above, according to the receiver and the desired wave-to-interference wave power ratio measurement method according to the present embodiment, the power value of the received signal for each base station transmission antenna is measured, and the synchronization determination is performed based on the combined value. Therefore, the synchronization determination can be performed based on the power value of the received signal regardless of whether or not the phase control is performed. Therefore, even if the base station phase control is not performed correctly and the received signal of the receiver becomes small, even in the initial state of transmission diversity CL1, communication can be established if the base station phase control is performed correctly. In this case, it is determined that synchronization is established and communication can be established.

  In the above embodiment, the example in which the average calculation unit 310 is arranged between the demodulation unit 200 and the RSCP calculation unit 320 has been described. However, the average calculation unit 310 is arranged between the RSCP calculation unit 320 and the SIR calculation unit 340. It may be the case. In this case, the average calculation unit 310 does not average the data for each antenna, but averages the RSCP calculated by the RSCP calculation unit 320 in a predetermined section (time).

(Embodiment 2)
FIG. 5 is a block diagram showing an example of a configuration of a receiver according to Embodiment 2 of the present invention. In addition, since the thing of the same code | symbol as FIG. 1 has the same name and the same function, description is abbreviate | omitted.

  The SIR measurement apparatus 500 is different from FIG. 1 in that it includes an RSCP calculation unit 520 and an SIR calculation unit 540. The RSCP calculation unit 520 employs a configuration in which an addition unit 521 and a squaring unit 522 are added to the RSCP calculation unit 320 of FIG. The RSCP calculation unit 520 outputs two types of RSCP values.

  Adder 521 performs vector addition of the demodulated symbols for each antenna. The vector addition is, for example, when the received symbol of the antenna 1 is I (ant1) + jQ (ant1) and the received symbol of the antenna 2 is I (ant2) + jQ (ant2), the vector addition result I (combine) + jQ (combine) Is represented by I (combine) + jQ (combine) = I (ant1) + I (ant2) + j (Q (ant1) + Q (ant2)). The squaring unit 522 squares the demodulated symbols added by the adding unit 521 and calculates a power value.

  The SIR calculation unit 540 receives two types of RSCP from the RSCP calculation unit 520 and also inputs a synchronization determination result indicating synchronization establishment and synchronization unestablishment from the synchronization determination unit 600, and the RSCP to be used is determined based on the synchronization determination result. Switch to calculate SIR. Synchronization determination unit 600 outputs a synchronization determination result indicating synchronization establishment and synchronization not established to SIR calculation unit 540. The synchronization determination result may be a synchronization determination result obtained and estimated by any method. For example, the synchronization determination unit 600 may be signaled by the base station that synchronization has been established, or may be inferred from the sequence state in which communication is established. Alternatively, since there is a high possibility that synchronization has not been established for the first several times, synchronization is not established, and after that, synchronization is established.

  Next, operations will be described with respect to differences from the first embodiment. The RSCP calculation unit 520 inputs the modulation symbol output from the averaging unit 311a to the squaring unit 321a and the addition unit 521, and inputs the modulation symbol output from the averaging unit 311b to the squaring unit 321b and the addition unit 521. Then, two types of RSCP are output from the adder 322 and the squaring unit 522, respectively. The RSCP output from the adder 322 is referred to as power addition RSCP, and the RSCP output from the squaring unit 522 is referred to as vector addition RSCP.

  The SIR calculation unit 540 receives two types of RSCP (power addition RSCP and vector addition RSCP) from the RSCP calculation unit 520. In addition, when the synchronization determination unit 600 is notified of establishment of synchronization as the synchronization determination result, the SIR calculation unit 540 selects the vector addition RSCP output from the squaring unit 522 and the synchronization determination unit 600 generates the synchronization determination result. When notification of establishment of unsynchronization is received, the RSCP notified from the adding unit 322 is selected. The SIR calculation unit 540 calculates the SIR using the selected RSCP and outputs the SIR to the synchronization determination unit 600. As described above, the SIR calculation unit 540 calculates the SIR by switching between the power addition RSCP output from the addition unit 322 and the vector addition RSCP output from the squaring unit 522 according to the synchronization determination result.

  Next, the power value of the received signal and the synchronization determination result according to the present embodiment will be described with reference to FIG. The received signal is the same as described in the first embodiment. When synchronization is not established (before synchronization is established), the base station does not perform phase control. Therefore, the receiver may receive a received signal of a desired channel with the quality of the received signal C. In such a case, if the base station performs phase control, the receiver can receive the received signal of the desired channel with the quality of the received signal D. For this reason, it is desired to calculate the SIR device by using the power addition RSCP, whereby synchronization can be established.

  On the other hand, after establishing synchronization, the base station performs phase control. Therefore, the receiver receives the reception signal of the desired channel (data symbol) with the quality of the reception signal D. When the RSCP calculation unit 520 performs vector addition of modulation symbols (pilot symbols) for each antenna and then squares to calculate the power value, the vector addition RSCP, that is, the power value of the received signal D is correctly calculated. . For this reason, after the synchronization is established, the receiver can perform synchronization determination with higher accuracy by using the SIR calculated by using the vector addition RSCP.

  As described above, according to the receiver and the desired wave-to-interference wave power ratio measurement method of the present embodiment, the SIR calculation procedure can be changed according to the synchronization determination result, and high-accuracy synchronization according to the reception situation is possible. Judgment can be made. Specifically, if synchronization is not established, the power addition RSCP is calculated to measure the received power for each base station transmission antenna, and synchronization determination can be made based on the combined value. Regardless, it is possible to perform synchronization determination that is not affected by phase control. Therefore, even in the initial state of transmission diversity CL1 in which base station phase control is not performed correctly and the mobile station received signal becomes small, communication can be established if base station phase control is performed correctly. Determines that synchronization is established and communication can be established. In addition, after synchronization is established, after the base station enters a state where appropriate phase control is performed, the received signal quality of the desired channel (data symbol) is accurately measured by calculating the vector addition RSCP. Therefore, highly accurate synchronization determination can be performed.

  In addition, in order to distinguish each component included in the SIR measuring apparatus 500, the configuration shown in FIG. 1, the squaring units 321a and 321b, and the adding unit 322 are replaced with the first squaring units a and b and the first adding unit, respectively. The configuration added in FIG. 5, the adding unit 521 and the squaring unit 522 may be a second adding unit and a second squaring unit, respectively.

  Moreover, although the SIR calculation part 540 showed the structure which inputs a synchronous determination result from the synchronous determination part 600, the case where a synchronous determination result is input from another component may be sufficient.

  In the above embodiment, the average calculation unit 310 has been described as being disposed between the demodulation unit 200 and the RSCP calculation unit 520. However, the average calculation unit 310 is disposed between the RSCP calculation unit 520 and the SIR calculation unit 540. It may be the case. In this case, the average calculation unit 310 does not average the data for each antenna, but averages the two types of RSCP calculated by the RSCP calculation unit 520 in a predetermined section (time).

  Furthermore, in each of the above embodiments, an example using pilot symbols has been described, but data symbols can also be used.

  Further, in each of the above embodiments, the configuration of the ISCP calculation unit 330 shown in FIG. 2 is an example, and the case where ISCP is calculated by another configuration or a method other than the procedure described in the present embodiment. It doesn't matter.

  Since the receiver according to the present invention calculates RSCP using the power value for each antenna, it is suitable for use in SIR measurement used in a communication system to which transmission diversity for controlling a transmission antenna is applied. In particular, since the power value for each of the plurality of antennas arranged in the base station is measured and the power values are added to obtain RSCP, synchronization determination can be performed without being affected by the presence or absence of phase control. Therefore, even in the initial state of transmission diversity CL1 before phase control is performed in the base station, if synchronization can be established after the base station performs phase control, it is determined that synchronization is established and communication is possible. In addition, the communication system to be applied includes a CDMA system in which standardization activity is performed in 3GPP.

FIG. 2 is a block diagram showing an example of a configuration of a receiver according to Embodiment 1 of the present invention. The block diagram which shows an example of a structure of an ISCP calculation part The figure which shows the structure of the data symbol and pilot symbol of DPCH The figure which shows the relationship between the symbol and power transmitted from two antennas in the receiver FIG. 3 is a block diagram showing an example of a configuration of a receiver according to Embodiment 2 of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Decoding part 200 Demodulation part 300, 500 SIR measuring device 310 Average calculation part 311a, 311b Average part 320,520 RSCP calculation part 322,521 Addition part,
321a, 321b, 522 Squared unit 330 ISCP calculation unit 340, 540 SIR calculation unit 400, 600 Synchronization determination unit

Claims (3)

Demodulating means for demodulating symbols transmitted from two antennas and outputting two demodulated symbols;
Squaring means for calculating a power value of each of the two demodulated symbols;
Adding means for calculating the desired wave power by adding the two power values;
Interference wave power calculating means for calculating interference wave power from the two demodulated symbols;
A desired wave-to-interference wave power ratio calculating means for calculating a desired wave-to-interference wave power ratio by dividing the desired wave power by the interference wave power;
A receiver comprising: A second adding means for inputting two demodulated symbols from the demodulating means and adding the two demodulated symbols to calculate an added demodulated symbol;
A second squaring means for calculating a second desired wave power of the additive demodulated symbol,
The desired wave-to-interference wave power ratio calculating means inputs a synchronization determination result indicating whether synchronization with the base station is established or not, and when the synchronization determination result is synchronization established, the second desired wave power The desired signal to interference signal power ratio is calculated using the desired signal, and if the synchronization determination result indicates that synchronization is not established, the desired signal to interference signal power ratio is calculated using the desired signal power. Receiver. Demodulating symbols transmitted from two antennas and outputting two demodulated symbols;
Calculating a power value of each of the two demodulation symbols;
Calculating the desired wave power by adding the two power values;
Calculating interference wave power from the two demodulated symbols;
Dividing the desired wave power by the interference wave power to calculate a desired wave to interference wave power ratio;
A method for measuring a desired wave-to-interference wave power ratio.

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