JP2005012386A - Method for estimating sir and receiver - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable an amount of calculation to be reduced by finger combining a square of the amplitude of a propagation path estimation value calculated by using a slot before a present slot without performing a synchronous detection, and considering as a desired wave power in a receiver having an SIR estimating function. <P>SOLUTION: A method for estimating the SIR includes a step of inputting a pilot signal after despreading to the propagation path high speed estimation unit 202, and obtaining the propagation path estimation value by using only the slot (.., k-2, k-1, k) before the present slot. The method further includes a step of calculating the square of the amplitude by directly inputting the propagation path estimation value without synchronous detection of a signal power calculation unit 2, then inputting an output obtained by finger combining of the square value of the amplitude of the propagation path estimation value in each path as a reception signal power (desired wave power) to an M slot average unit 3, and calculating the average reception signal power Ps for the M slot. Meanwhile, the method also includes a step of inputting interference power obtained from a pilot symbol and the average reception symbol point after the finger combining in an interference power calculation unit 211 to an N slot moving average unit 5, and calculating the average interference power Pi for the N slot. A reception SIR estimation value calculator 4 calculates an SIR estimation value from the average reception signal power Ps and the average interference power Pi. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to transmission power control of a mobile communication system, and more particularly, to a receiver having a function of estimating a desired signal power to interference signal power ratio (received signal power to interference signal ratio) and a desired signal power pair in the receiver. The present invention relates to an interference wave power ratio estimation method.
[0002]
[Prior art]
In a mobile communication system using a CDMA (Code Division Multiple Access) communication system, when a plurality of mobile stations transmit to one base station, if the received power from each mobile station is almost equal, it is spread for each mobile station. Since the codes are different, the base station can distinguish and receive a signal from a desired mobile station.
[0003]
However, the distance of each mobile station from the base station varies, and even when each mobile station transmits with the same transmission power, the received power at the base station takes various values for each mobile station. When attention is paid, signals from other mobile stations become interference waves, and signals may not be distinguished if signal power from other mobile stations is large.
[0004]
Therefore, the base station measures the ratio of the received power from other mobile stations to the received power from one mobile station, and transmits a signal for controlling the transmission power to each mobile station. Transmission power control is performed to keep the reception power at the base station constant regardless of the distance of the station.
[0005]
In order to perform the optimal control of the transmission power control, it is required to accurately estimate a received signal power to interference power ratio (SIR) signal-to-interference plus noise power ratio (SIR).
[0006]
The SIR is a basic parameter that is directly related to reception quality such as bit error rate in a mobile communication system, and is used to grasp system characteristics such as reception quality using a pilot signal whose signal pattern is known in advance by the receiver. Sought for two purposes of transmit power control.
[0007]
In the transmission power control, regardless of the distance from the base station, the transmission power is set so that the reception quality of the signal from each mobile station in the base station or the reception quality of the desired signal from the base station in each mobile station is the same. Take control.
[0008]
That is, in the closed-loop transmission power control, the target reception quality at the reception side apparatus is determined in advance as the target reception quality, and the transmission power at the transmission side apparatus is set so that the actually measured reception quality approaches this target reception quality. To control.
[0009]
Generally, SIR is measured as the reception quality parameter, and control is performed to determine whether the transmission power is increased or decreased by comparison with a target SIR value.
[0010]
In a propagation environment in a mobile communication system, a fading phenomenon in which the amplitude of a signal changes drastically in time occurs, so that received signal power changes greatly in time, but interference power is random in time.
[0011]
Therefore, the SIR (SIR estimated value) for performing transmission power control is averaged with respect to received signal power in a short period, and averaged with respect to interference power in a long period to obtain an estimated value that follows fading.
[0012]
On the other hand, SIR (SIR measurement value) for grasping system characteristics averages received signal power and interference power in the same period in order to obtain a measurement value with higher accuracy and stability.
[0013]
As a conventional technique of the SIR calculation, Non-Patent Document 1 discloses a technique of performing SIR calculation using a pilot signal after finger (RAKE) synthesis.
[0014]
FIG. 24 is a diagram illustrating an example of the SIR calculation using the technique disclosed in Non-Patent Document 1.
[0015]
In FIG. 24, a finger (RAKE) synthesis unit 401 performs finger synthesis on the synchronous detection output of each path, and an in-slot averaging unit 402 averages the in-phase component and the quadrature component of the pilot signal after the finger synthesis in units of slots. Find the average received symbol point.
[0016]
The power calculation unit 404a calculates the power of the average received symbol point, outputs the obtained power as received signal power, and averages the received signal power for m slots by the m slot average unit 405a to obtain the average received signal power. Ask.
[0017]
On the other hand, the subtractor 403 and the power calculation unit 404b input the pilot signal after the finger combination and the average received symbol point, calculate a dispersion value for each slot, and output this dispersion value as interference power. An average unit 405b averages the interference power for n slots to obtain an average interference power.
[0018]
The multiplier 407 multiplies the average received signal power by the reciprocal of the average interference power obtained by the reciprocal unit 406 to calculate the SIR value.
[0019]
FIG. 25 is a diagram illustrating an example of an apparatus when application of the SIR calculation of FIG. 24 is considered.
(1) First, in order to obtain the SIR estimated value, the propagation path (channel) high-speed estimation unit 202 inputs the despread pilot signal and outputs the propagation path estimated value.
[0020]
The provisional determination synchronous detection unit 203 multiplies the despread pilot signal by the complex conjugate value of the channel estimation value to perform synchronous detection, and then performs finger detection (RAKE) synthesis and in-slot averaging processing (not shown) And output an average received symbol point.
[0021]
The signal power calculation unit 204 of the SIR estimation unit 319 outputs the power obtained by calculating the power of the average received symbol point as the received signal power, and the M slot average unit 205 averages the received signal power for M slots. To calculate the average received signal power.
[0022]
On the other hand, interference power calculation section 206 inputs the pilot signal after finger synthesis (not shown) and the average received symbol point to calculate interference power, and N slot moving average section 207 moves the interference power for N slots. Average to obtain the average interference power.
[0023]
Received SIR estimated value calculating section 208 calculates an SIR estimated value by multiplying the average received signal power by the inverse of the average interference power, and outputs the SIR estimated value to the TPC bit creating section.
(2) Next, in order to obtain the SIR measurement value, the propagation path estimation unit 209 obtains the propagation path estimation value from the despread pilot signal, and the determination synchronous detection unit 210 obtains the complex conjugate value of the propagation path estimation value. After the despread pilot signal is multiplied and synchronous detection is performed, finger synthesis and intra-slot averaging processing (not shown) are performed to obtain an average received symbol point.
[0024]
The signal power calculation unit 213 of the SIR measurement unit 320 outputs the power obtained by calculating the power of the average reception symbol point as reception signal power, and the L slot average unit 214 averages the reception signal power for L slots. To calculate the average received signal power.
[0025]
Interference power calculation section 211 calculates the interference power by inputting the pilot signal after finger combination (not shown) and the average received symbol point, and L slot averaging section 212 averages the interference power for L slots. Find the interference power.
[0026]
The received SIR measurement value calculation unit 215 calculates an SIR estimated value by multiplying the average received signal power by the inverse of the average interference power, and reports it to the upper layer.
[0027]
Note that the slots used for the averaging are performed in order to improve the accuracy of each value. For example, M = 2, L = 3, and N = 100 may be used.
[0028]
FIG. 26 is a configuration example of a propagation path (channel) estimation unit and a synchronous detection unit.
[0029]
The propagation path estimation unit 209 for obtaining the SIR measurement value performs averaging using pilot signals in slots (···, k−1, k, k + 1, ···) before and after the current slot (slot k). On the other hand, the propagation path high-speed estimation unit 202 for calculating the SIR estimation value performs averaging using only the previous slot (.., k-2, k-1, k) from the current slot. Therefore, compared with the propagation path estimation unit 209, the delay is small and high speed estimation is possible.
[0030]
The determination synchronous detection unit 210 and the provisional determination synchronous detection unit 203 have different names for convenience in order to distinguish between SIR estimation and SIR measurement, and the configurations are the same. is there.
[0031]
In FIG. 26, a propagation path estimation unit 209 is a propagation path estimation unit that obtains a propagation path estimation value based on a despread pilot signal, and performs in-slot in-slot addition (averaging) of the despread pilot signal. An in-slot in-phase addition unit 209a, a delay element (D) 209b that delays the in-slot in-phase addition result by one slot, a multiplier 209c that multiplies a weighting coefficient (correction amount) Wi according to a propagation condition, The adder 209d adds the delay outputs.
[0032]
The synchronous detector 210a is configured by a multiplier 210b that multiplies the despread pilot signal (delayed signal matched to the propagation path estimation process) by the complex conjugate of the propagation path estimated value. Based on the above, synchronous detection of the pilot signal is performed.
[0033]
[Non-Patent Document 1]
Shunsuke Kiyo, 3 others, “Reception SIR measurement method using pilot symbols in DS-CDMA transmission power control”, IEICE Technical Report, IEICE, RCS96-74 (1996-08), p. 57-62
[0034]
[Problems to be solved by the invention]
However, in the conventional SIR estimation method, the SIR estimation unit for transmission power control and the SIR measurement unit for grasping system characteristics each independently calculate the average received signal power and the average interference power, and then compare the ratio. Therefore, there is a problem that the calculation amount becomes large.
[0035]
In particular, the synchronous detector multiplies the pilot signal after despreading by the complex conjugate value of the propagation path estimation value, and this processing must be performed on each finger for the number of pilot symbols in the slot. First, multiply and multiply operations are used.
[0036]
For this reason, when it is realized by software processing using a DSP or the like, the amount of calculation increases, and when it is realized by hardware, the circuit scale increases, and the scale of the entire apparatus increases accordingly. There is a problem that it is difficult to realize a small and large capacity device.
[0037]
The present invention was devised in view of such problems, and an object of the present invention is to provide a receiver having an SIR estimation function that reduces the amount of calculation and reduces the hardware scale, and an SIR estimation method in the receiver.
[0038]
[Means for Solving the Problems]
The present invention obtains the square of the magnitude of the channel estimation value obtained by the channel high-speed estimation unit as the received signal power without performing synchronous detection in the SIR estimation unit necessary for transmission power control, and the average interference The amount of calculation is reduced by obtaining the power with the SIR measurement unit.
[0039]
Further, the SIR estimation unit optimizes the system by switching between the first SIR estimation unit having a small calculation amount and the second SIR estimation unit having a higher accuracy in accordance with the fluctuation of the propagation environment.
[0040]
Specifically, in the SIR estimation method for estimating the S / I ratio that is the ratio of the desired wave power and the interference wave power, the square of the absolute value of the propagation path estimated value calculated from the pilot signal in the slot before the current slot is calculated. A step of outputting the input and rake-combined signal as desired wave power, and a pilot signal is synchronously detected and rake-combined using the propagation path estimated value calculated from the pilot signal in the current slot and the slots before and after the current slot A step of outputting a signal dispersion value as interference wave power and a step of calculating a ratio between the desired wave power and the interference wave power and outputting the ratio as an SIR estimation value are provided.
[0041]
Also, in the CDMA receiver having SIR estimation means for estimating the S / I ratio that is the ratio of the desired wave power and the interference wave power, the first propagation path estimated value calculated from the pilot signal in the slot before the current slot The pilot signal is synchronously detected using the desired wave power, which is a rake-combined signal by inputting the square of the absolute value, and the propagation path estimation value calculated from the pilot signal in the current slot and the slots before and after the current slot, and the rake is detected. The first SIR estimating means for calculating the ratio of the combined signal dispersion value to the interference wave power and outputting the calculated value as the first SIR estimated value, and the pilot using the first propagation path estimated value The signals are synchronously detected and rake combined, and the ratio between the desired wave power, which is the square value of the absolute value of the combined signal, and the interference wave power, which is the variance value of the combined signal, is calculated. SI Switching between switching between the first SIR estimating means and the second SIR estimating means based on any one of the number of processing channels, the target SIR value, and the fading frequency estimated value, and the second SIR estimating means that outputs the estimated value Means may be provided.
[0042]
The transmission power control bit generating means for generating a transmission power control bit by comparing the SIR estimated value with the target SIR value, and the transmission power control bit generating means is provided when the fading frequency estimated value is larger than a threshold value. The transmission power control bit may be generated so that the transmission power is within a predetermined range.
[0043]
Further, either one of a correcting unit that corrects the second SIR estimated value based on the first SIR estimated value or a correcting unit that corrects the first SIR estimated value based on the second SIR estimated value is provided. You may make it provide.
[0044]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 23 is a diagram illustrating a schematic configuration example of a receiving apparatus of the CDMA communication system.
[0045]
A signal received by the antenna 301 is input to a band pass filter (BPF) 302 to obtain a signal from which components outside a predetermined band are removed.
[0046]
Frequency converters 303a and 303b multiply the predetermined out-of-band removal signal by a carrier generated by local oscillator 304 and a carrier obtained by shifting the phase of the carrier by π / 2 phase shifter 305 by π / 2, thereby receiving baseband Output in-phase and quadrature components of the signal.
[0047]
The received baseband signal is subjected to A / D conversion by removing unnecessary high-frequency components by low-pass filters (LPF) 306a and 306b, adjusting the amplitude to a constant level by AGC (Auto Gain Control) units 307a and 307b. The digital signals are converted by the devices 308a and 308b and input to the searcher unit 309 and the finger units 310a and 310b.
[0048]
The searcher unit 309 detects a multipath by obtaining a correlation value between a known pilot component in a received baseband signal and a spreading sequence, determines despreading timing corresponding to each path, and performs finger units 310a and 310b. To enter.
[0049]
Pilot part despreading section 311 in each finger section 310a, 310b performs despreading according to the timing detected by searcher section 309 and outputs a pilot signal (pilot symbol).
[0050]
The data part despreading unit 312 performs a despreading process according to the timing detected by the searcher unit 309 and outputs a data signal (data symbol).
[0051]
The inter-slot delay detection unit 313 performs inter-slot delay detection that calculates a phase difference between slots based on the input pilot symbol sequence.
[0052]
The propagation path (channel) estimation unit 314 adds (averages) the in-phase component and the quadrature component of the despread pilot signal in each slot, and the fading frequency estimation value f between the slots. _D Each of the outputs subjected to the weighting according to the frequency and the phase compensation according to the frequency deviation estimated value Δf is added to output the propagation path estimated value.
[0053]
Pilot section synchronous detection section 315 performs pilot signal synchronous detection by multiplying the despread pilot signal by the complex conjugate of the propagation path estimation value.
[0054]
Similarly, the data portion synchronous detection unit 316 multiplies the despread data signal and the complex conjugate of the propagation path estimation value to perform synchronous detection (demodulation) of the data signal.
[0055]
A finger (RAKE) combining unit 317 performs finger combining of signals output from the finger units 310a and 310b.
[0056]
Of the finger-combined signals, the pilot delay detection result is input to a fading frequency estimation unit 318 and a frequency deviation estimation unit 322. The data synchronous detection result (demodulated data) is input to the error correction unit 321.
[0057]
The fading frequency estimation unit 318 estimates the fading frequency from the phase difference calculated by the inter-slot delay detection unit 313 and estimates the value f _D The frequency deviation estimation unit 322 estimates the carrier frequency deviation between the transceiver (mobile station and base station) and outputs the estimated value Δf.
[0058]
The error correction unit 321 corrects transmission errors and outputs an information signal.
[0059]
A TPC (Transmit Power Control) transmission bit control unit 323 compares the estimated SIR value with a reference value, generates a TPC bit so that the SIR does not fall below the reference value, and transfers the TPC bit to the transmitter.
[0060]
The SIR estimating unit 319 and the SIR measuring unit 320 will be described later as the SIR estimating unit 101 and the SIR measuring unit 104.
[0061]
In the present invention, the technique described in detail below is applied to a receiver as shown in FIG.
[0062]
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0063]
(First Embodiment) FIG. 1 shows an embodiment of a CDMA receiver to which the SIR estimation method of the present invention is applied.
[0064]
Note that the same parts as those in FIG.
[0065]
The fast propagation path estimation unit 202 receives the despread pilot signal, and obtains a propagation path estimated value using only the previous slot (.., k-2, k-1, k) from the current slot.
[0066]
The first SIR estimation unit 102 includes a signal power calculation unit 2, an M slot average unit 3, and a received SIR estimated value calculation unit 4.
[0067]
The signal power calculation unit 2 directly inputs the propagation path estimated value without performing synchronous detection and calculates the square of the propagation path estimated value, and then calculates the propagation path estimated value 2 in each path. The multiplier value is subjected to finger synthesis, and the finger synthesis output is output as received signal power.
[0068]
The M slot averaging unit 3 receives the received signal power and averages the received signal power for M slots to calculate an average received signal power Ps.
[0069]
Received SIR estimated value calculating section 4 receives average received signal power Ps and average interference power value Pi from SIR measuring means 104 described later, calculates an SIR estimated value, and outputs it to the TPC bit creating section.
[0070]
The propagation path estimation unit 209 receives the despread pilot signal and uses the pilot signals in the slots (··, k−1, k, k + 1,...) Before and after the current slot (slot k) to propagate the propagation path. After obtaining an estimated value and performing synchronous detection in the determination synchronous detection unit 210, finger synthesis and intra-slot averaging processing (not shown) are performed to obtain an average received symbol point.
[0071]
The interference power calculation unit 211 calculates the interference power by inputting the pilot signal after combining the fingers and the average received symbol point, and the N slot moving average unit 5 inputs the interference power and performs a moving average of the interference power for N slots. Then, the average interference power Pi is calculated.
[0072]
Received SIR estimated value calculating section 4 calculates an SIR estimated value from average received signal power Ps and average interference power Pi, and outputs the calculated SIR estimated value to the TPC bit creating section.
[0073]
FIG. 2 is a configuration example of the signal power calculation unit 2, the M slot average unit 3, and the received SIR estimated value calculation unit 4 in the first SIR estimation unit 102.
[0074]
In FIG. 2, 2a of the signal power calculation unit 2 is the square of the magnitude of the propagation path estimation value (I ² + Q ² 2b is a weighting factor table that outputs a set of weighting factors w for each finger (path) when performing finger synthesis, and 2c is the size of the propagation path estimation value calculated by each finger. A multiplier for multiplying the square by each weighting factor, 2d is a finger synthesis unit.
[0075]
3a of the M slot averaging unit 3 is a delay element D that delays the finger combined output by one slot, 3b is a weighting factor table that outputs a set w of weighting factors for each slot, and 3c is a multiplier for each delay output. A multiplier, 3d is an adder for adding each weighted delay output, 4a of the received SIR estimated value calculation unit 4 is an inverse number for calculating the inverse of the average interference power Pi obtained by the SIR measuring means 104, and 4b is an average. It is a multiplier that multiplies the received signal power Ps by the reciprocal to calculate an SIR estimated value.
[0076]
Next, the operation of this configuration example will be described.
[0077]
The square calculation unit 2a directly inputs the propagation path estimation value obtained by the propagation path high-speed estimation unit 202 without performing synchronous detection, and calculates the square of the size of each path. After correction is performed by multiplying the obtained square value by a weighting factor, finger synthesis is performed, and the finger synthesis output is used as received signal power.
[0078]
The reason why the finger synthesis is performed after the square of the propagation path estimated value will be described below.
[0079]
If the position vector of pilot symbol i after despreading is ri, the position vector with the same phase is ri ′, and i = 1, 2, 3, 4, 5 as shown in FIG. Since re is an average value obtained by performing in-phase addition for each symbol in the slot, it is expressed by the following equation (1).
[0080]
re = (r1 ′ + r2 ′ + r3 ′ + r4 ′ + r5 ′) / 5 (1)
Here, the propagation path estimated value re in each finger may take a positive value or a negative value as shown in FIG. 4 and FIG. Cannot be used to perform finger synthesis.
[0081]
For this reason, it is necessary to perform finger combination after first squaring the propagation path estimation value of each finger.
[0082]
2 inputs the received signal power to the delay element (D) 3a, the multiplier 3c performs correction by multiplying each delay output by a weighting factor, and the adder 3d performs correction. The average received signal power Ps is calculated by averaging the subsequent delayed outputs.
[0083]
The reception SIR estimated value calculation unit 4 calculates the SIR estimated value by multiplying the average received signal power Ps and the inverse value of the average interference power Pi by the multiplier 4b, and outputs it to the TPC bit creation unit.
[0084]
As described above, in the first SIR estimating means, the received signal power obtained by directly squaring the propagation path estimated value without performing synchronous detection and performing finger synthesis and the interference power obtained by the SIR measuring means are used. By calculating the SIR estimated value, the deviation from the SIR measured value calculated by the SIR measuring means is larger than that of the second SIR estimating means, but the amount of calculation can be reduced.
[0085]
(Second Embodiment) FIG. 6 shows another embodiment of the CDMA receiver to which the SIR estimation method of the present invention is applied.
[0086]
The second embodiment differs from the first embodiment in that the SIR estimation method control unit 1 is provided, the first SIR estimation means 102 and the second SIR estimation means 103 are switched, and the despread pilot signal. Is a point to input.
[0087]
In the first embodiment, the SIR estimated value is calculated by the first SIR estimating means 102.
[0088]
In the second embodiment, the SIR estimation method control unit 1 switches between the first SIR estimation unit 102 with a small processing amount and the high-precision second SIR estimation unit 103 according to conditions.
[0089]
When the first SIR estimation unit is selected by the SIR estimation method control unit 1, the N-slot moving average unit 5 of the SIR measurement unit 104 obtains the average interference power Pi and inputs it to the first SIR estimation unit. And output SIR estimate.
[0090]
When the second SIR estimation means is selected, the pilot signal after despreading is input to perform provisional determination synchronous detection, and then each process is performed to output an SIR estimated value.
[0091]
FIG. 7 is an explanatory diagram of the SIR estimating means 101 in the second embodiment, and the SIR estimating means 101 is composed of a first SIR estimating means 102 and a second SIR estimating means 103.
[0092]
Since the first SIR estimating means 102 has the same configuration as that of the first embodiment, description thereof is omitted.
[0093]
The second SIR estimation means 103 includes a provisional determination synchronous detection unit 203, a signal power calculation unit 204, an M slot average unit 205, an interference power calculation unit 206, an N slot moving average unit 207, and a received SIR estimated value calculation unit 208. 25, and is the same as the configuration of the SIR estimation unit 319 and the provisional decision synchronous detection unit 203 (finger synthesis and in-slot averaging processing not shown) in the prior art in FIG. A description thereof will be omitted.
[0094]
One of the two SIR estimation means is selected and switched by the SIR estimation method control unit 1 in accordance with a propagation condition, for example, a fading frequency.
[0095]
According to the second embodiment, the first SIR estimating means with a small processing amount and the second SIR estimating means with higher accuracy are switched according to the propagation condition, so that a more suitable system can be constructed. Can do.
[0096]
(Third Embodiment) FIG. 8 shows another embodiment of the CDMA receiver to which the SIR estimation method of the present invention is applied. The same parts as those of the second embodiment of FIG.
[0097]
The difference from the second embodiment is that an input from the processing channel number management unit 6 is provided.
[0098]
In the third embodiment, either the first SIR estimation means or the second SIR estimation means is selected according to the number of channels that need to be processed in a unit functional block (for example, one communication card that performs CDMA communication). To switch.
[0099]
The number of processing channels is input as system information from a processing channel number management unit 6 located in an RNC (Radio Network Controller) or BTS (Base Transceiver Station) that constitutes the mobile communication system. The
[0100]
FIG. 9 is a flowchart showing the processing flow of the third embodiment.
[0101]
Specified value N for the number of processing channels ₀ It is determined whether to execute the first SIR estimation means or the second SIR estimation means depending on whether it is larger (20a).
[0102]
The number of processing channels is N ₀ If larger, the first SIR estimation means with a small processing amount is executed (20b), and TPC bit creation is performed (20d).
[0103]
The number of processing channels is N ₀ If it is not larger (same or smaller), the second SIR estimation means is executed (20c), and TPC bit creation is performed (20d).
[0104]
The specified value N for the number of processing channels ₀ Is determined by the ratio of the processing capability (processing amount) of the unit functional block to the processing amount of the second SIR estimation means per channel.
[0105]
According to the third embodiment, since the first SIR estimating means having a small processing amount and the second SIR estimating means having a higher accuracy are switched according to the number of processing channels, a more suitable system is constructed. be able to.
[0106]
(Fourth Embodiment) FIG. 10 shows another embodiment of the CDMA receiver to which the SIR estimation method of the present invention is applied. The same parts as those of the second embodiment of FIG.
[0107]
The difference from the second embodiment is that the target SIR value is input to the SIR estimation method control unit 1.
[0108]
In the fourth embodiment, the SIR estimation means is selected according to the target SIR value calculated based on the error correction output data.
[0109]
FIG. 11 is a flowchart showing the processing flow of the fourth embodiment.
[0110]
The target value r for which the target SIR value is predetermined ₀ The SIR estimation means to be executed is determined depending on whether it is smaller (21a).
[0111]
Target SIR value is specified value r ₀ Since the smaller channel has good performance, the first SIR estimation means with a small processing amount is executed (21b), and the second SIR estimation means is executed otherwise (21c).
[0112]
Target value r of target SIR value ₀ For example, bit error rate BER = 10 ^-3 SIR value necessary for maintaining
[0113]
According to the fourth embodiment, since the first SIR estimating means having a small processing amount and the second SIR estimating means having higher accuracy are switched according to the target SIR value, a more suitable system is constructed. be able to.
[0114]
(Fifth Embodiment) FIG. 12 shows another embodiment of the CDMA receiver to which the SIR estimation method of the present invention is applied. The same parts as those of the second embodiment of FIG.
[0115]
The difference from the second embodiment is that an input from the fading frequency estimation unit 318 is provided.
[0116]
In the fifth embodiment, the fading frequency estimation value f _D The SIR estimation means is selected in accordance with the size of.
[0117]
FIG. 13 is a flowchart showing the processing flow of the fifth embodiment.
[0118]
The fading frequency estimation value is a predetermined value f determined in advance. ₀ The SIR estimation means to be executed is determined depending on whether it is smaller (22a).
[0119]
Fading frequency estimated value is specified value f ₀ If it is smaller, the first SIR estimating means has almost the same accuracy as the second SIR estimating means.
[0120]
For this reason, the first SIR estimating means having a small processing amount is applied (22b), and if not, the second SIR estimating means is applied (22c).
[0121]
Specified value f of fading frequency estimate ₀ Is determined by the processing capability of the unit functional block and the number of processing channels.
[0122]
According to the fifth embodiment, the first SIR estimating means with a small processing amount and the second SIR estimating means with higher accuracy are switched according to the fading frequency estimated value, so that a more suitable system can be constructed. It can be carried out.
[0123]
(Sixth Embodiment) FIG. 14 shows another embodiment of the CDMA receiver to which the SIR estimation method of the present invention is applied. The same parts as those in FIG.
[0124]
Since the first SIR estimation means and the second SIR estimation means have different calculation methods for reducing the amount of calculation, there is a slight difference between the estimation results of both.
[0125]
By correcting this deviation, it is possible to improve the accuracy of transmission power control.
[0126]
In the sixth embodiment, the deviation of the estimation result that occurs between the first SIR estimation means and the second SIR estimation means is corrected by correcting the weight coefficient table value used when performing M slot averaging in advance. Then, the SIR estimated value is corrected.
[0127]
That is, in FIG. 14, the switching corrected weighting coefficient table 7 in which coefficients for correcting the deviation of the estimation result are set is used.
[0128]
The switching corrected weighting coefficient table 7 will be described below.
[0129]
The set value of the weighting factor table is a weighting factor α for each slot when adding power of M slots. _k And the power of the kth slot is p _k Then, the M slot average power P is expressed by the following equation (2).
[0130]
P = ■ (α _k ・ P _k (2)
For example, when the number of slots M = 3 and the third slot is the current slot, the weight coefficient α _k An example of the table is shown in FIG.
[0131]
Now, assuming that the SIR estimated values obtained by the first SIR estimating means and the second SIR estimating means are x and y, respectively, and the relationship y = f (x) is established, the first SIR estimating means is used as a reference. In this case, the set value of the switching corrected weighting coefficient table 9 in the second SIR estimating means can be calculated as shown in FIG.
[0132]
As described above, the accuracy of the transmission power control is improved by correcting the weighting coefficient table value used when performing M-slot averaging so that the estimation results of the first SIR estimation unit and the second SIR estimation unit match. It can be further increased.
[0133]
In the sixth embodiment, the case where the SIR estimation unit uses the first SIR estimation unit 102 as a reference has been described. However, the same description can be made using the second SIR estimation unit 103 as a reference.
[0134]
(Seventh Embodiment) FIG. 17 shows another embodiment of the CDMA receiving apparatus to which the SIR estimation method of the present invention is applied. The same parts as those in FIG.
[0135]
When the propagation environment changes, the SIR estimated value and the SIR measured value are different from each other in calculation method, resulting in a deviation V.
[0136]
For this reason, when the path model which is one of the propagation conditions changes, the deviation V also changes.
[0137]
Even if the path model changes, if the deviation V is corrected to be 0 or constant, the accuracy of transmission power control can be improved.
[0138]
In the seventh embodiment, the SIR estimation value is corrected by correcting in advance the weighting coefficient table value used when performing finger synthesis.
[0139]
That is, as shown in FIG. 17, a path model corrected weighting coefficient table 8 in which a coefficient for correcting the deviation V is set when performing finger synthesis is used.
[0140]
The path model corrected weight coefficient table 8 will be described below.
[0141]
The set value of the weighting factor table is the weighting factor β for each finger when the fingers are combined. _i In the case of the first SIR estimation means, the signal power of each finger is represented by u _i If the power after finger synthesis is U, the power U after finger synthesis is expressed by the following equation (3).
[0142]
U = ■ (β _i ・ U _i (3)
For example, the weighting factor β when the number of fingers is 4 _i An example of the table is shown in FIG.
[0143]
Here, when the finger composition is performed using the maximum ratio composition, for example, the weighting coefficient can be obtained by the following equation (4).
[0144]
β _i = G (i) = u _i / U (4)
If the path model corresponding to the weighting coefficient table in FIG. 18 is the path model 1 shown in FIG. 19, when the path model is changed to the path model 2 as shown in FIG. 20, the SIR estimated value and the actual SIR value (SIR measured value) The deviation V also changes.
[0145]
For this reason, the weighting factor β _i Is corrected according to the path model.
[0146]
Now, the SIR estimated value is x, the actual SIR value is y, and y for the path model j _i = F _i Assuming that the relationship (x) holds, the set values in the path model corrected weight coefficient table 8 are expressed as shown in FIG.
[0147]
As described above, the accuracy of transmission power control can be improved by correcting the weighting coefficient table value used when performing finger synthesis so as to correct the deviation between the SIR estimated value and the SIR measured value.
[0148]
(Eighth Embodiment) FIG. 22 shows another embodiment of the CDMA receiving apparatus to which the SIR estimation method of the present invention is applied. The same parts as those in FIG.
[0149]
When the fading frequency changes, the deviation V between the SIR estimated value and the SIR measured value also changes.
[0150]
Even if the fading frequency changes, the accuracy of transmission power control can be improved if the deviation V is corrected to be 0 or constant.
[0151]
In the eighth embodiment, the SIR estimated value is corrected by correcting the deviation V by correcting in advance the weighting coefficient table value used when performing finger synthesis.
[0152]
That is, as shown in FIG. 22, a fading corrected weight coefficient table 9 in which a coefficient for correcting the deviation V is set is used.
[0153]
Similar to the change of the path model, the deviation V between the SIR estimated value x and the actual SIR value y is also caused by the magnitude of the fading frequency.
[0154]
Dividing the magnitude of fading frequency into three stages, y for stage j _i = F _i If the relationship (x) holds, the setting values of the fading corrected weight coefficient table 9 in this case are also expressed as shown in FIG.
[0155]
As described above, the accuracy of transmission power control can be improved by correcting the weighting coefficient table value used when performing finger synthesis so as to correct the deviation between the SIR estimated value and the SIR measured value.
[0156]
In the seventh and eighth embodiments, the first SIR estimating means has been described as an example, but the case of the second SIR estimating means can be described in the same manner.
[0157]
In the sixth to eighth embodiments, the switching-corrected weighting coefficient table value is corrected so that the estimation results of the first SIR estimating unit and the second SIR estimating unit match. The SIR estimation error is adjusted from the bit error rate (or frame error rate) by correcting the table values of the first SIR estimation unit and the second SIR estimation unit based on the actual SIR value obtained by the above. This makes it possible to omit the processing of the outer loop to be performed and reduce the amount of calculation.
[0158]
However, when fading is extremely severe, the transmission power control based on the SIR estimation value cannot catch up with the change of the propagation path, and the reception characteristics deteriorate.
[0159]
Therefore, the fading frequency is the reference value f. _Th If larger, a TPC bit pattern that instructs to maintain the current transmission power within a certain range is generated without performing SIR estimation, and transmission power is controlled.
[0160]
If there is a TPC bit pattern for instructing maintenance of transmission power, that pattern is generated; otherwise, a TPC bit pattern that means increasing transmission power and a TPC bit pattern that means decreasing are alternately And control so that the transmission power is within a certain range.
[0161]
The main inventions disclosed in this specification are summarized as follows.
[0162]
(Supplementary note 1) In an SIR estimation method for estimating an S / I ratio that is a ratio of desired wave power and interference wave power,
A step of inputting a square of an absolute value of a propagation path estimated value calculated from a pilot signal in a slot before the current slot and outputting a rake synthesized signal as a desired wave power;
Outputting, as interference wave power, a dispersion value of a signal obtained by synchronously detecting a pilot signal using a propagation path estimated value calculated from a pilot signal in a current slot and slots before and after the current slot and rake-combining the pilot signal;
Calculating a ratio between the desired wave power and the interference wave power and outputting it as an SIR estimated value;
A SIR estimation method characterized by comprising: (Claim 1)
(Supplementary Note 2) In an SIR estimation method for estimating an S / I ratio that is a ratio of desired wave power and interference wave power,
An SIR estimation method comprising a step of inputting a square of an absolute value of a propagation path estimation value calculated from a pilot signal in a slot before the current slot and outputting a rake-combined signal as desired wave power. (Claim 2)
(Supplementary Note 3) In a CDMA receiver having SIR estimation means for estimating an S / I ratio that is a ratio of desired wave power and interference wave power,
The desired wave power, which is a rake-combined signal by inputting the square of the absolute value of the first propagation path estimated value calculated from the pilot signal in the slot before the current slot, and the current slot and the slots in the slots before and after the current slot Using the propagation path estimated value calculated from the pilot signal, the pilot signal is synchronously detected and a ratio with the interference wave power that is a dispersion value of the rake synthesized signal is calculated, and the calculated value is output as the first SIR estimated value First SIR estimation means for:
The pilot signal is synchronously detected and synthesized using the first propagation path estimated value, and a desired wave power that is a square value of the absolute value of the synthesized signal and an interference wave power that is a dispersion value of the synthesized signal A second SIR estimating means for calculating a ratio and outputting the calculated value as a second SIR estimated value;
Switching means for switching between the first SIR estimating means and the second SIR estimating means based on any one of the number of processing channels, the target SIR value, and the fading frequency estimated value;
A CDMA receiver characterized by comprising: (Claim 3)
(Appendix 4) The apparatus of claim 3,
Transmission power control bit generation means for generating a transmission power control bit by comparing the SIR estimated value and the target SIR value;
The transmission power control bit generating means has a configuration for generating the transmission power control bit so that transmission power falls within a predetermined range when a fading frequency estimation value is larger than a threshold value. (Claim 4)
(Appendix 5) The apparatus of claim 3,
Either correction means for correcting the second SIR estimated value based on the first SIR estimated value or correction means for correcting the first SIR estimated value based on the second SIR estimated value is provided. A CDMA receiver characterized by the above. (Claim 5)
(Appendix 6) The apparatus of Appendix 3,
A CDMA receiving apparatus comprising correction means for correcting the first SIR estimated value or the second SIR estimated value based on one of a path model and a fading frequency.
[0163]
(Supplementary note 7) In an SIR estimation method for estimating an S / I ratio that is a ratio of desired wave power and interference wave power,
The desired wave power, which is a rake-combined signal by inputting the square of the absolute value of the first propagation path estimated value calculated from the pilot signal in the slot before the current slot, and the current slot and the slots before and after the current slot A ratio between the pilot signal and the interference wave power, which is a dispersion value of the rake synthesized signal, is calculated by using the propagation path estimated value calculated from the pilot signal, and the calculated value is used as the first SIR estimated value. A first SIR estimation step to output;
The pilot signal is synchronously detected and synthesized using the first propagation path estimated value, and a desired wave power that is a square value of the absolute value of the synthesized signal and an interference wave power that is a dispersion value of the synthesized signal A second SIR estimating step of calculating a ratio and outputting the calculated value as a second SIR estimated value;
A switching step for switching between the first SIR estimation step and the second SIR estimation step;
A SIR estimation method characterized by comprising:
[0164]
(Appendix 8) The switching step includes
The SIR estimation method according to appendix 7, wherein the first SIR estimation step and the second SIR estimation step are switched based on any one of the number of processing channels, the target SIR value, and the fading frequency estimation value.
[0165]
(Supplementary note 9) a transmission power control bit generation step of generating a transmission power control bit by comparing the SIR estimated value and the target SIR value;
The transmission power control bit generation step has a function of generating the transmission power control bit so that the transmission power is within a predetermined range when a fading frequency estimation value is larger than a threshold value. SIR estimation method.
[0166]
【The invention's effect】
According to the present invention, by using the first SIR estimation means having a small processing amount, the amount of calculation can be reduced when the processing is realized by software processing using a DSP or the like, and the case is realized by hardware. The circuit scale can be reduced.
[0167]
In addition, the system can be optimized by switching the first SIR estimation unit and the second SIR estimation unit in the SIR estimation unit according to the propagation path characteristics.
[0168]
Further, the accuracy of transmission power control can be improved by correcting the weighting factor in advance for the SIR estimation value and SIR measurement value generated by the calculation method and propagation path characteristics.
[Brief description of the drawings]
FIG. 1 is a diagram showing a first embodiment of the present invention.
FIG. 2 is a diagram illustrating a configuration example of a signal power calculation unit, an M slot average unit, and a received SIR estimated value calculation unit according to the present invention.
FIG. 3 is a diagram illustrating a position vector (1) of pilot symbols and propagation path estimation values after despreading;
FIG. 4 is a diagram illustrating a position vector (2) of pilot symbols and propagation path estimation values after despreading.
FIG. 5 is a diagram illustrating a position vector (3) of pilot symbols and propagation path estimation values after despreading;
FIG. 6 is a diagram showing a second embodiment of the present invention.
FIG. 7 is an explanatory diagram of SIR estimation means 101 of the second embodiment.
FIG. 8 is a diagram showing a third embodiment of the present invention.
FIG. 9 is a diagram showing a processing flow of a third embodiment.
FIG. 10 is a diagram showing a fourth embodiment of the present invention.
FIG. 11 is a diagram showing a processing flow of a fourth embodiment.
FIG. 12 is a diagram showing a fifth embodiment of the present invention.
FIG. 13 is a diagram showing a processing flow of a fifth embodiment.
FIG. 14 is a diagram showing a sixth embodiment of the present invention.
FIG. 15 is a diagram showing an example (1) of the switching-corrected weighting coefficient table according to the present invention.
FIG. 16 is a diagram showing an example (2) of the switching-corrected weighting coefficient table according to the present invention.
FIG. 17 is a diagram showing a seventh embodiment of the present invention.
FIG. 18 is a diagram showing an example (1) of a path model corrected weighting coefficient table according to the present invention;
FIG. 19 is a diagram showing a path model (1).
FIG. 20 is a diagram showing a path model (2).
FIG. 21 is a diagram showing an example (2) of the path model corrected weighting coefficient table according to the present invention;
FIG. 22 is a diagram showing an eighth embodiment of the present invention.
FIG. 23 is a diagram illustrating a configuration example of a receiving device of a CDMA communication method.
FIG. 24 is a diagram showing an example of a conventional SIR calculation.
FIG. 25 is a diagram illustrating an example of a conventional SIR measurement unit and SIR estimation unit.
FIG. 26 is a diagram illustrating a configuration example of a propagation path estimation unit and a synchronous detection unit.
[Explanation of symbols]
1 SIR estimation method controller
2, 204, 213 Signal power calculator
2a square calculator
2b Weight coefficient table
2c multiplier
2d Finger synthesis unit
3, 205 M slot average part
4,208 Received SIR estimated value calculation unit
5,207 N-slot moving average part
6 Number of processing channels management section
7 Switched weight coefficient table
8 Path model corrected weight coefficient table
9 Fading corrected weight coefficient table
101 SIR estimation means
102 1st SIR estimation means
103 2nd SIR estimation means
104 SIR measurement means
202 High-speed channel (channel) estimation unit
203 Tentative decision synchronous detector
206, 211 Interference power calculator
209 Channel (channel) estimation unit
210 Judgment synchronous detector
210a Synchronous detection unit
212, 214 L slot average part
215 Received SIR measurement value calculation unit
314 Channel (Channel) Estimator
315 Pilot section synchronous detection section
318 Fading frequency estimation unit
319 SIR estimation unit
320 SIR measurement unit

Claims (5)

In an SIR estimation method for estimating an S / I ratio that is a ratio of desired wave power and interference wave power,
A step of inputting a square of an absolute value of a propagation path estimated value calculated from a pilot signal in a slot before the current slot and outputting a rake synthesized signal as a desired wave power;
Outputting, as interference wave power, a dispersion value of a signal obtained by synchronously detecting a pilot signal using a propagation path estimated value calculated from a pilot signal in a current slot and slots before and after the current slot and rake-combining the pilot signal;
Calculating a ratio between the desired wave power and the interference wave power and outputting it as an SIR estimated value;
A SIR estimation method characterized by comprising: In an SIR estimation method for estimating an S / I ratio that is a ratio of desired wave power and interference wave power,
An SIR estimation method comprising a step of inputting a square of an absolute value of a propagation path estimation value calculated from a pilot signal in a slot before the current slot and outputting a rake-combined signal as desired wave power. In a receiving apparatus having SIR estimation means for estimating an S / I ratio that is a ratio of desired wave power and interference wave power,
The desired wave power, which is a rake-combined signal by inputting the square of the absolute value of the first propagation path estimated value calculated from the pilot signal in the slot before the current slot, and the current slot and the slots in the slots before and after the current slot Using the propagation path estimated value calculated from the pilot signal, the pilot signal is synchronously detected and a ratio with the interference wave power that is a dispersion value of the rake synthesized signal is calculated, and the calculated value is output as the first SIR estimated value First SIR estimation means for:
The pilot signal is synchronously detected and synthesized using the first propagation path estimated value, and a desired wave power that is a square value of the absolute value of the synthesized signal and an interference wave power that is a dispersion value of the synthesized signal A second SIR estimating means for calculating a ratio and outputting the calculated value as a second SIR estimated value;
Switching means for switching between the first SIR estimating means and the second SIR estimating means based on any one of the number of processing channels, the target SIR value, and the fading frequency estimated value;
A receiving apparatus comprising: The apparatus of claim 3, comprising:
Transmission power control bit generation means for generating a transmission power control bit by comparing the SIR estimated value and the target SIR value;
The transmission apparatus according to claim 1, wherein the transmission power control bit generation unit generates the transmission power control bit so that the transmission power is within a predetermined range when a fading frequency estimation value is larger than a threshold value. The apparatus of claim 3, comprising:
Either correction means for correcting the second SIR estimated value based on the first SIR estimated value or correction means for correcting the first SIR estimated value based on the second SIR estimated value is provided. A receiver characterized by.

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