WO2008001421A1 - Reception quality measuring method - Google Patents
Reception quality measuring method Download PDFInfo
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- WO2008001421A1 WO2008001421A1 PCT/JP2006/312746 JP2006312746W WO2008001421A1 WO 2008001421 A1 WO2008001421 A1 WO 2008001421A1 JP 2006312746 W JP2006312746 W JP 2006312746W WO 2008001421 A1 WO2008001421 A1 WO 2008001421A1
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W52/00—Power management, e.g. TPC [Transmission Power Control], power saving or power classes
- H04W52/04—TPC
- H04W52/18—TPC being performed according to specific parameters
- H04W52/22—TPC being performed according to specific parameters taking into account previous information or commands
- H04W52/225—Calculation of statistics, e.g. average, variance
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B17/00—Monitoring; Testing
- H04B17/20—Monitoring; Testing of receivers
- H04B17/26—Monitoring; Testing of receivers using historical data, averaging values or statistics
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L25/00—Baseband systems
- H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
- H04L25/0202—Channel estimation
Definitions
- the present invention relates to a reception quality measurement method in a wireless system such as a wireless LAN or a cellular system.
- FDMA frequency division multiple access
- TDMA time division multiple access
- CDMA code division multiple access
- each channel signal can be separated relatively easily by a filter or a time window. Therefore, the received signal quality can be measured by assuming that the receiver noise power is constant. I helped.
- each user signal is separated based on the orthogonality of the code.
- the orthogonality of the code is not always maintained due to the influence of the multipath transmission path and the received signal is large. In some cases, interference components remain. For this reason, in CDMA, it is necessary to measure the residual interference power as well as simply measuring the reception level. The following two methods were used to separate and measure the signal in the received signal and the residual interference component including receiver noise.
- FIG. 1 shows the concept of a conventional MIMO transmission system.
- the MIMO transmitter 10 includes known symbols from M transmit antennas TxANT 0 to TxANT M-1 for each frame time. Transmit pattern and k-channel TDM multiplexed signal. These are mixed and received by the N receiving antennas RxANT-0 to RxANT-N-1 of the MIMO receiver 20.
- the service area is narrow or divided into subcarriers when combined with OFDM transmission, frequency selective fading due to multinos propagation path delay differences can be ignored, so the transmission line matrix
- Each element is a complex number, and the following equation holds between the transmitted symbol and the received symbol.
- N -1 is the received symbol at the i th receiving antenna (1)
- h .. is the transmission coefficient between the jth transmitting antenna and the transmitting antenna
- the signal separation unit 21 of the MIMO receiver 20 is a signal for obtaining M signals transmitted from M antennas TxANT-0 to TxANT-M-1 on the transmission side from N received symbols. Separation is performed (this is equivalent to despreading in CDMA transmission). Signal separation is performed in two stages: channel estimation and separation.
- Spatial filter bank method based on ZF algorithm or MMSE algorithm A method that separates signals one by one with a filter that has a coefficient calculated from the transmission path matrix H.
- Interference canceller method A method in which a signal separated by a spatial filter is re-encoded and multiplied by a transmission line matrix H to generate a replica, and this is separated while increasing SIR by subtracting the received signal power. .
- the quality measurement of the received signal in MIMO transmission is obtained by measuring the known symbol distortion in the separated signal by the known symbol distortion measurement units 22-0 to 22-M-1.
- FIG. 2 shows known symbols in the separated signal. As shown in the figure, even if a known symbol with the same amplitude is transmitted, its received amplitude fluctuates, so that it is separated as a result of residual interference components and receiver noise, and the power is calculated by dividing it. The quality of the separated signal can be obtained.
- FIG. 3 is an explanatory diagram of received signal quality measurement based on provisional determination, and shows constellation during 16QAM symbol reception.
- the nearest 16QAM reception point is selected as the temporary decision value, and the difference between the actual received symbol and the temporary decision value is received as the residual interference component.
- Non-Patent Document 1 Daibell: “Promotion and Elemental Technology of MIMO System”, IEICE, Antenna 'Design for Propagation' Analysis Workshop (29Z30), 2004/11
- the number of known symbols that can be used is usually limited in order to avoid an extreme decrease in the transmission rate, so that it is difficult to obtain sufficient accuracy.
- the central limit According to the theorem, it is difficult to achieve high accuracy with the conventional measurement method that uses only known symbols with limited power that improves 3 dB accuracy each time the number of measurement symbols is doubled.
- frame synchronization is necessary to identify the reception time of known symbols, so it takes time to start reception start force measurement, and measurement is not possible in a low SINR environment where synchronization is likely to be lost. There was a problem of becoming possible.
- the method of 2. above has a problem that if the provisional judgment value has an error, a large error occurs in the measured value, and numerical stability cannot be obtained.
- An object of the present invention is to provide a reception quality measurement method that can easily perform highly accurate and stable reception signal quality measurement even when the reception signal includes a large amount of residual interference components.
- the reception quality measurement method of the present invention measures the non-Gaussianity of the signal distribution of the reception signal, and determines that the quality of the reception signal is better as the non-Gaussianity is larger.
- the quality of the received signal can be measured based on non-Gaussianity, which can be measured without separating the signal and the residual interference component, and can be correctly judged even with a low-level signal. Therefore, even when the received signal contains a lot of residual interference components, it becomes possible to easily perform highly accurate and stable received signal quality measurement.
- FIG. 1 Diagram showing the concept of a conventional MIMO transmission system
- FIG. 4 is a diagram for explaining the first embodiment which is an application example of the reception quality measurement method according to the present invention.
- FIG. 5 shows an embodiment in which the reception quality measurement method according to the present invention is used for reception diversity control.
- FIG. 6 is a diagram for explaining the third embodiment in which the reception quality measurement method according to the present invention is used for transmission diversity control.
- FIG. 7 is a diagram for explaining Embodiment 4 in which the reception quality measurement method according to the present invention is used for link adaptation of a MIMO transmission system.
- the reception quality measurement method according to the present invention is used for transmission power control of MIMO transmission systems.
- the feature of the present invention is that when the transmission signals that are independent of each other according to the non-Gaussian distribution are mixed, the central limit theorem approximates the Gaussian distribution. Is to measure. Incidentally, the transmission signal has a non-Gaussian distribution as is clear from the constellation. Non-Gaussianity can be quantified with statistics such as higher-order cumulant negentropy.
- non-Gaussianity is a concept unrelated to the signal level, quality judgment can be performed correctly even with a low-level signal. For example, if there is a low-level signal that does not contain residual interference components, it will be low quality if judged by the reception level, but it will become high quality if judged by non-Gaussianity.
- non-Gaussianity is a statistic that can be measured without separating the signal and the residual interference component. Therefore, no known symbols are required for measurement, and high-accuracy measurement using all received symbols can be performed. In addition, since frame synchronization is not required for measurement, measurement is easy, and measurement can be started at the same time as reception starts, so the pull-in time can be shortened.
- the present invention has been achieved with reference to independent component analysis represented by a component analysis) algorithm, which is based on non-Gaussian principle.
- Fast-ICA when multiple source signals follow non-Gaussian distributions independent of each other, these mixed signals approach the Gaussian distribution by the central limit theorem, and conversely maximize the non-Gaussianity of the separated signal.
- Kurtosis kurtosis
- negentropy a quantity representing non-Gaussianity and a quantity representing separation performance
- Transmission data of mobile communication is obviously non-Gaussian distribution (because it is a discrete distribution) and is considered to be independent from each other, and the same method can be applied. In other words, if there are many residual interference components and receiver noise in the separated signal, the non-Gaussianity will decrease, and if these are small, the non-Gaussianity will increase.
- the test mobile device 100 is provided with a non-Gaussian measuring device 103 that measures (evaluates) the quality of the received signal based on the non-Gaussian property of the received signal.
- the non-Gaussian measuring device 103 receives a reception signal that is received by the antenna 101 and subjected to predetermined radio reception processing such as down-conversion and analog digital conversion by the receiver 102.
- the non-Gaussianity measuring device 103 is configured to obtain a quality measurement result that the higher the non-Gaussianness is, the better the reception quality is.
- the radio wave from the test base station 200 is received by the test mobile device 100, and the quality measurement result of the received signal is accumulated, so that the propagation state of the traveling course And estimate the transmission characteristics at each point and formulate a placement plan .
- reception quality has been evaluated by measuring the reception level.
- the non-Gaussian measuring device 103 is mounted on a portable terminal, a display corresponding to the actual reception quality can be performed rather than the reception electrolysis strength display.
- This embodiment presents that the present invention is applied to reception diversity control.
- a signal transmitted from the transmitting station 300 is received by a plurality of antennas RxANT-0 to RxANT-N1 of the receiving station 400.
- the reception quality of the signals received by the respective antennas RxANT-0 to RxANT-N-1 is measured by the respective non-Gaussian measuring units 401-0 to 401-N-1.
- each of the non-Gaussian measurement units 401-0 to 401-N-1 obtains a quality measurement result that the higher the non-Gaussian property, the better the reception quality, based on the non-Gaussian property of the received signal. .
- Each non-Gaussian measurement unit 401-0 to 401-N-1 sends the measurement result obtained in this way to diversity combining unit 402.
- Diversity combining section 402 diversity combines the received signals obtained by antennas RxANT-0 to RxANT-N-1 based on the measurement results.
- a single stream signal is transmitted even with one antenna, and this is received by multiple antennas, and diversity combining is performed according to the reception level at the reception antenna, thereby reducing the SNR. Improvements have been made to obtain good reception characteristics. Furthermore, in a propagation environment where there are large interference waves where radio waves from multiple transmitters arrive, simple reception levels (including interference waves) do not accurately represent the reception quality.
- the quality of the signal obtained by each of the receiving antennas RxANT—0 to RxANT —N—l is measured using non-Gaussianity, and this is used for diversity combining. Since the index is used, it is possible to realize highly accurate and stable reception diversity control regardless of the presence or absence of interference waves and without being affected by the frame synchronization performance. In addition, versatile reception diversity independent of the frame format can be realized.
- This embodiment presents that the present invention is applied to transmission diversity control. Specifically, the quality of the received signal is measured with high accuracy on the receiving side based on non-Gaussianity, and the coefficient of transmission diversity is set with high accuracy based on this measurement result.
- the transmission diversity control according to the present embodiment will be described with reference to FIG.
- the transmitting station 500 copies a single stream signal by the number of transmission antennas by the weighting copy branching unit 501 and increases the number of transmission antennas, and multiplies them by a weighting coefficient, so that a plurality of transmission antennas TxAN T—0 to TxANT—M—1 minute The transmission signal is formed.
- the receiving station 600 receives these mixed signals with one antenna.
- the channel estimation unit 601 performs channel estimation based on known symbol distortion. This channel estimation value is wirelessly transmitted to the transmission station 500 via the transmission device 602.
- the receiving station 600 has a non-Gaussian measuring unit 603, and the non-Gaussian measuring unit 603 receives a non-Gaussian signal. Measure the resistance.
- the non-Gaussianity measuring unit 603 transmits a transmission instruction signal instructing the transmission apparatus 602 to transmit a channel estimation value only when the non-Gaussianity of the received signal becomes lower than a predetermined threshold.
- transmission station 500 changes the transmission diversity weighting factor based on the channel estimation value in transmission diversity control section 502 and sends the result to weighting copy branching section 501. To do.
- the weighting factor of this transmission diversity is calculated based on the channel estimation value obtained at the receiving station 600 so that it can be satisfactorily received by the receiving antenna RxANT.
- channel estimation accuracy greatly affects transmission characteristics.
- the channel estimation value obtained by the channel estimation unit 601 is performed using known symbols with a limited number, the value fluctuates, and it is not always good to update every time a known symbol is received.
- the quality of the channel estimation value is determined using the non-gaussiness of the received signal, and the channel estimation value is fed back to transmitting station 500 only when the quality is degraded. I tried to do it.
- the transmitting station 500 holds the current value while the value is not updated by feedback.
- the feedback information is transmitted only when it is necessary to substantially change the coefficient of transmission diversity, so that radio resources required for feedback can be saved and transmission errors in the feedback path can be reduced and stable. Transmit diversity can be realized.
- non-Gaussianity is used, highly accurate and stable transmission diversity control can be realized regardless of the presence or absence of interference waves and without being affected by the frame synchronization performance.
- This embodiment proposes that the present invention is applied to link adaptation of a MIMO transmission system.
- Transmitting station 700 transmits M-channel transmission data from a plurality of antennas TxANT 0 to TxANT M ⁇ 1 via MIMO error control encoding section 701 and MIMO modulation section 702.
- Receiving station 800 inputs signals received by a plurality of antennas RxANT-0 to RxANT-N-1 to MIMO signal demultiplexing section 801.
- MIMO signal demultiplexing section 801 performs channel estimation, and further uses this channel estimation value to generate M transmission signals X to X using separation algorithms such as a spatial filter bank method, an interference canceller method, and a maximum likelihood determination method. corresponds to x
- M separated signals z-z are used for MIMO error correction recovery.
- Error correction decoding is performed by the signal key unit 802 to be received data for M channels.
- the receiving station 800 can measure non-Gaussianity of each separated signal z to z.
- the quality measurement results of the separated signals z to z obtained by the non-Gaussian measuring units 803-0 to 803-M 1 are sent to the transmitting station 700.
- the per-stream MCS control unit 703 controls the error correction coding rate and the modulation multi-level number according to the quality of each stream (each separated signal), thereby reducing variations in transmission characteristics between streams. Specifically, the per-stream MCS control unit 703 sends error signals to streams corresponding to the separated signals z to z by sending control signals to the MIMO error control code unit 701 and the MIMO modulation unit 702.
- the coding rate and the modulation multi-level number are set for each separated signal z to z.
- the present invention is applied to transmission power control of a MIMO transmission system. It is the person who presents.
- Transmission power control according to the present embodiment will be described with reference to FIG. 8 in which parts corresponding to those in FIG.
- the quality of each separated signal z to z is measured by the non-Gaussian measuring unit 803—0 to 803—M—1 at the receiving station 800, and the measurement result is sent to the transmitting station 900.
- the quality measurement results of the separated signals z to z are input to the transmission power control unit 902. Sending
- the transmission power control unit 902 controls the transmission power in each transmission radio circuit 901-0 to 901-M-1 according to the quality of each stream (each separated signal), so that the required transmission quality of each stream is To reduce the transmission of unnecessary radio waves. Specifically, the transmission power control unit 902 sends the transmission power control signals to the respective transmission radio circuits 901-0 to 901-M-1, so that the separated signals z to z are transmitted.
- the transmission power for the stream corresponding to 0 M-1 is controlled according to the quality of each separated signal z to z.
- This embodiment presents a preferred measurement method as a method for measuring non-Gaussianity. Specifically, we present that the absolute value of the higher-order cumulant of the received signal is used as a non-Gaussian index.
- the non-Gaussianity measuring method of the present embodiment calculates a fourth-order cumulant called Kurtosi s (also referred to as Kurtosis) shown in the following equation with respect to the received signal, and the absolute value is large.
- Kurtosi s also referred to as Kurtosis
- the signal is strong, that is, the signal quality (SINR) is high.
- the expression (2) is Kurtosis that is normalized by power.
- ⁇ [ ⁇ ] represents the average of the set. This set average ⁇ [ ⁇ ] should be calculated by replacing it with the time average as is often done in practice. Unlike the conventional quality measurement method using known symbols, equation (2) is executed for all received symbols, so a more accurate quality measurement result can be obtained.
- the third-order or higher-order cumulant is theoretically 0 for the Gaussian signal, so that not only Kurtosis but also the third-order or higher-order cumulant can be used to perform the same non-Gaussian measurement.
- the k-th order cumulant K is the coefficient when the cumulant generating function K (t) that is the logarithm of the product moment generating function M (t) is Tiller-expanded as shown in Eq. (7).
- Kurtosis a fourth-order cumulant, is a statistic whose value changes according to the sharpness of the probability density distribution, as shown in FIG. In other words, it is 0 for the Gaussian distribution, positive values for Super Gaussian, and negative values for Sub-Gaussian. Therefore, the absolute value of Kurtosis is a measure for non-Gaussianity, but since it includes the fourth power of the signal, the value changes sensitively even if an abnormal value is mixed even in one sample due to noise mixing. Lacks robustness. However, Kurtosis is often used because of its convenient properties as shown in Equation (8).
- the method of determining non-Gaussianity based on the higher-order cumulant absolute value presented in the present embodiment can be widely applied to quality measurement of received signals. For example, when measuring the quality of a separated signal in a MIMO receiver, it is determined that the higher the cumulant absolute value, the stronger the non-Gaussianity, that is, the separated signal quality (SINR) is high. be able to. (Embodiment 7)
- This embodiment presents a preferred measurement method as a method for measuring non-Gaussianity. Specifically, we propose that the negentropy of the received signal be a non-Gaussian index.
- the non-Gaussianity measuring method of the present embodiment calculates an approximate statistic called approximate negentropy represented by the following equation for the received signal, and the larger this value, the stronger the non-Gaussianity, that is, the signal Judged as high quality (SINR).
- K Attention, k is a positive constant as follows.
- Equation (9) it is assumed that z is normalized to an average of 0 and a variance of 1 before execution of the calculation.
- ⁇ [ ⁇ ] represents the set average. This set average ⁇ [ ⁇ ] should be calculated by replacing it with the time average as is often done in practice.
- Fig. 10 shows the negentropy when the shape of the distribution is changed by the parameter ⁇ in the probability density distribution shown in equation (10) and the approximate negentropy according to equation (9) under two conditions. is there. For any, Eq. (9) is a good approximation of negentropy under either condition.
- negentropy that is 0 when the signal has a Gaussian distribution and a positive value otherwise is devised as shown in equation (14).
- a large negentropy means that the non-Gaussian property of z is large, so it can be used as a measure of non-Gaussian property, and it has low sensitivity and robustness to outliers.
- Equation 14 3 ⁇ 4au SS is a Gaussian signal with mean and variance equal to 2.
- Negentropy approximation methods is a method based on the following polynomial approximation.
- this method includes a kurtosis in the second term on the right side, so that a large approximation error occurs depending on the shape of the distribution as shown by the broken line in FIG.
- MEM maximum entropy method
- the distribution that maximizes the entropy of the signal is the estimated value of the Z distribution.
- the method of determining non-Gaussianity by negentropy presented in this embodiment can be widely applied to the quality measurement of received signals. For example, when measuring the quality of the separated signal in a MIMO receiver, it is determined that the non-Gaussianity is more strongly separated as the negentropy value is larger, that is, the separated signal quality (SINR) is higher. Can do. Industrial applicability
- the present invention is advantageous in that it is possible to easily perform highly accurate and stable reception signal quality measurement even when the reception signal includes a large amount of residual interference components.
- Device, receive diversity device, transmit diversity control, MIMO transmission system link It is useful when applied to quadration, transmission power control, path quality measurement, and the like.
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Abstract
A reception quality measuring method in which received signal quality can be easily measured with high precision and stability even if the received signal contains many residual interference components. A non-Gaussian measuring apparatus (103) measures the non-Gaussian property of the distribution of the received signal and determines that as the non-Gaussian property increases, the quality of the received signal is improved. This enables correct measurement of the quality of the received signal without separating the signal from the residual interference components albeit the signal is at a low level.
Description
明 細 書 Specification
受信品質測定方法 Reception quality measurement method
技術分野 Technical field
[0001] 本発明は、無線 LANやセルラなどの無線システムにおける受信品質測定方法に 関する。 [0001] The present invention relates to a reception quality measurement method in a wireless system such as a wireless LAN or a cellular system.
背景技術 Background art
[0002] 従来、移動通信システムのチャネル多重方式として、 FDMA、 TDMA、 CDMAが 実用化されてきた。現在ユーザ数を増カロさせても伝送帯域幅が増カロしな ヽ唯一の方 式として、 MIMO伝送による空間多重方式(SDMA方式)が盛んに研究されている( 例えば非特許文献 1参照)。 Conventionally, FDMA, TDMA, and CDMA have been put to practical use as channel multiplexing schemes for mobile communication systems. Currently, even if the number of users is increased, the transmission bandwidth does not increase, but the only method that can be used is the spatial multiplexing method (SDMA method) using MIMO transmission (for example, see Non-Patent Document 1).
[0003] これらのどの方式を用いた場合でも、適切な処理を様々に切換え選択して実行す るための判断基準となる、受信信号品質の測定機能が非常に重要となる。 [0003] Regardless of which of these methods is used, a function for measuring received signal quality, which is a criterion for selecting and executing appropriate processing in various ways, is very important.
[0004] ここで FDMA及び TDMAでは、各チャネル信号がフィルタや時間窓により比較的 容易に分離できるので、受信信号の品質は、受信機雑音電力を一定と考えて受信 信号レベルを測定すればよ力つた。 [0004] Here, in FDMA and TDMA, each channel signal can be separated relatively easily by a filter or a time window. Therefore, the received signal quality can be measured by assuming that the receiver noise power is constant. I helped.
[0005] これに対して CDMAでは、各ユーザ信号はコードの直交性に基づいて分離される 力 実際にはマルチパス伝送路などの影響でコードの直交性が必ずしも保たれず、 受信信号に大きな干渉成分が残留する場合も生ずる。このため CDMAでは、単に 受信レベルを測定するだけでなぐ残留干渉電力も測定しなければならなくなった。 そして受信信号中の信号と、受信機雑音も含む残留干渉成分とを分離して測定する ために、以下の 2つの方法が用いられた。 [0005] On the other hand, in CDMA, each user signal is separated based on the orthogonality of the code. Actually, the orthogonality of the code is not always maintained due to the influence of the multipath transmission path and the received signal is large. In some cases, interference components remain. For this reason, in CDMA, it is necessary to measure the residual interference power as well as simply measuring the reception level. The following two methods were used to separate and measure the signal in the received signal and the residual interference component including receiver noise.
[0006] 1.既知シンボルを受信してその歪成分を残留干渉成分として分離する方法 [0006] 1. Method of receiving a known symbol and separating its distortion component as a residual interference component
2.受信シンボルを硬判定した仮判定値からのズレを残留干渉成分として分離する 方法 2. Method of separating the deviation from the provisional decision value obtained by hard decision on the received symbol as the residual interference component
[0007] 次に、 MIMO伝送における受信信号の品質測定について説明する。図 1に従来の MIMO伝送システムの概念を示す。図 1において、 MIMO送信装置 10は、 1フレー ム時間毎に M本の送信アンテナ TxANT 0〜TxANT M— 1から既知シンボル
パターンと kチャネル TDM多重信号を送出する。これらは交じり合って MIMO受信 装置 20の N本の受信アンテナ RxANT— 0〜RxANT— N— 1で受信される。ここで サービスエリアが狭い場合、または OFDM伝送と併用した時の各サブキャリア内に 分割して考えた場合、マルチノ スの伝搬経路遅延差による周波数選択性フェージン グを無視できるので、伝送路行列の各要素は複素数になり、送信シンボルと受信シ ンボルの間に次式が成立つ。なお、次式は行列表現で x = Hsと表わされる。 Next, received signal quality measurement in MIMO transmission will be described. Figure 1 shows the concept of a conventional MIMO transmission system. In FIG. 1, the MIMO transmitter 10 includes known symbols from M transmit antennas TxANT 0 to TxANT M-1 for each frame time. Transmit pattern and k-channel TDM multiplexed signal. These are mixed and received by the N receiving antennas RxANT-0 to RxANT-N-1 of the MIMO receiver 20. Here, when the service area is narrow or divided into subcarriers when combined with OFDM transmission, frequency selective fading due to multinos propagation path delay differences can be ignored, so the transmission line matrix Each element is a complex number, and the following equation holds between the transmitted symbol and the received symbol. The following equation is expressed as x = Hs in matrix representation.
[数 1] [Number 1]
( ヽ (ヽ
、
, ここで、 = = 0,1,· · ,N -1 は i番目の受信アンテナでの受信シンボル ( 1 ) , , Where = = 0,1,..., N -1 is the received symbol at the i th receiving antenna (1)
= 0,1,· · ·,Μ - 1 は j番目の送信アンテナからの送信シンボル = 0,1, ..., Μ-1 is the transmitted symbol from the jth transmit antenna
XJJ X J J
h.. は第 j送信ァンテナと第授信ァンテナ間の伝達係数 h .. is the transmission coefficient between the jth transmitting antenna and the transmitting antenna
1J 1J
[0008] MIMO受信装置 20の信号分離部 21は、 N個の受信シンボルから、送信側の M本 のアンテナ TxANT— 0〜TxANT— M—1で送信された M個の信号を得るための 信号分離を行う(これは CDMA伝送では逆拡散に相当する処理である)。信号分離 はチャネル推定と分離の 2段階で実行される。 [0008] The signal separation unit 21 of the MIMO receiver 20 is a signal for obtaining M signals transmitted from M antennas TxANT-0 to TxANT-M-1 on the transmission side from N received symbols. Separation is performed (this is equivalent to despreading in CDMA transmission). Signal separation is performed in two stages: channel estimation and separation.
[0009] まず、図 1にお!/、て送信アンテナ TxANT— 0が既知シンボルを送出して!/、る時間 は他の送信アンテナ TxANT— l〜TxANT— M— 1は信号を送出しないので、この 時の各受信アンテナ RxANT— 0〜RxANT— N— 1で受信された既知シンボルが どのような歪を受けたかを複素除算で検出し、その商が h , h , · · , h になる。 [0009] First, as shown in FIG. 1, because the transmitting antenna TxANT—0 transmits a known symbol! /, The other transmitting antennas TxANT—l to TxANT—M—1 do not transmit signals. At this time, the distortion of the known symbols received by each receiving antenna RxANT—0 to RxANT—N—1 is detected by complex division, and the quotient becomes h 1, h 2,. .
00 10 N- l 0 00 10 N- l 0
以下同様に送信アンテナ TxANT 1のみが既知シンボルを送出する時では h , h 一 01 1 Similarly, when only the transmitting antenna TxANT 1 transmits a known symbol, h and h 1 01 1
, · · , h t 、うように全要素を測定し、 N X M伝送路行列 Hを得ることができる。 ,..., H t, all elements can be measured to obtain an N X M transmission line matrix H.
1 N-l 1 1 N-l 1
これがチャネル推定である。このチャネル推定値を用いると受信シンボルベクトル yか ら元の送信シンボルベクトル Xを抽出分離することができる。この処理が信号分離部 2 1で行われる。信号分離部 21で行われる代表的なアルゴリズムとして、以下の 3つが 知られている。 This is channel estimation. Using this channel estimation value, the original transmission symbol vector X can be extracted and separated from the reception symbol vector y. This process is performed by the signal separation unit 21. The following three are known as typical algorithms performed in the signal separation unit 21.
[0010] (1)空間フィルタバンク法: ZFアルゴリズム又は MMSEアルゴリズムに基づいて伝
送路行列 Hから計算した係数を持つフィルタにて 1信号ずつ分離する方法。 [0010] (1) Spatial filter bank method: based on ZF algorithm or MMSE algorithm A method that separates signals one by one with a filter that has a coefficient calculated from the transmission path matrix H.
(2)干渉キャンセラ法:空間フィルタで分離した信号を再符号ィヒして伝送路行列 H を掛けてレプリカを発生し、これを受信信号力も差引くことにより SIRを高めながら分 離してゆく方法。 (2) Interference canceller method: A method in which a signal separated by a spatial filter is re-encoded and multiplied by a transmission line matrix H to generate a replica, and this is separated while increasing SIR by subtracting the received signal power. .
(3)最尤判定法:膨大な数の送信シンボルベクトル候補に伝送路行列 Hを掛けて 得られる受信シンボルベクトル候補の中から、実際の受信シンボルベクトルにユーク リツド距離が最小のものを選択する方法。 (3) Maximum likelihood determination method: From the reception symbol vector candidates obtained by multiplying a huge number of transmission symbol vector candidates by the transmission path matrix H, select the actual reception symbol vector with the smallest Euclidean distance. Method.
[0011] MIMO伝送における受信信号の品質測定は、既知シンボル歪測定部 22— 0〜22 — M— 1によって、分離信号中の既知シンボル歪を測定することによって得られる。 [0011] The quality measurement of the received signal in MIMO transmission is obtained by measuring the known symbol distortion in the separated signal by the known symbol distortion measurement units 22-0 to 22-M-1.
[0012] 図 2は分離信号中の既知シンボルを表したものである。図に示されているように、同 じ振幅の既知シンボルを送信してもその受信振幅は変動するので、これを残留干渉 成分や受信機雑音によるものとして分離し、その電力を計算することによって、分離 信号の品質を求めることができる。 FIG. 2 shows known symbols in the separated signal. As shown in the figure, even if a known symbol with the same amplitude is transmitted, its received amplitude fluctuates, so that it is separated as a result of residual interference components and receiver noise, and the power is calculated by dividing it. The quality of the separated signal can be obtained.
[0013] また図 3は仮判定による受信信号の品質測定の説明図で、 16QAMのシンボル受 信時のコンスタレーシヨンを表している。実際のシンボルが X印で示された位置に受 信された場合、これに最も近い 16QAM受信点を仮判定値として選択し、実際の受 信シンボルと仮判定値のずれを残留干渉成分と受信機雑音によるものとして分離し、 その電力を計算することによって、既知シンボルを含む全受信シンボルを用いて分 離信号の品質を求めることができる。 [0013] FIG. 3 is an explanatory diagram of received signal quality measurement based on provisional determination, and shows constellation during 16QAM symbol reception. When the actual symbol is received at the position indicated by X, the nearest 16QAM reception point is selected as the temporary decision value, and the difference between the actual received symbol and the temporary decision value is received as the residual interference component. By separating the signal due to machine noise and calculating its power, the quality of the separated signal can be obtained using all received symbols including known symbols.
非特許文献 1 :大鐘:「MIMOシステムの起訴と要素技術」,電子情報通信学会,アン テナ'伝搬における設計'解析ワークショップ (第 29Z30回) , 2004/11 Non-Patent Document 1: Daibell: “Promotion and Elemental Technology of MIMO System”, IEICE, Antenna 'Design for Propagation' Analysis Workshop (29Z30), 2004/11
発明の開示 Disclosure of the invention
発明が解決しょうとする課題 Problems to be solved by the invention
[0014] ところで、 CDMAや MIMOにおいて、受信信号の品質を測定するにあたっては、 上記 1.の方法や上記 2.の方法を用いるのが一般的である力 これらの方法には以 下のような問題があった。 [0014] By the way, in CDMA and MIMO, when measuring the quality of a received signal, it is common to use the method of 1. and the method of 2. These methods include the following: There was a problem.
[0015] 上記 1.の方法は、通常は伝送速度の極端な低下を避けるために利用できる既知 シンボル数が制限されるので、十分な精度を得ることが困難になる。例えば中心極限
定理によれば、測定シンボル数が 2倍になる毎に 3dB精度が向上する力 数に制限 のある既知シンボルのみを用いる従来の測定法では高精度化は困難である。し力も 測定するには既知シンボル受信時刻を識別するためのフレーム同期が必須となるの で、受信開始力 測定開始までの引き込み時間が必要な上、同期がはずれがちな 低 SINR環境では測定が不可能になるという問題があった。 [0015] In the method of 1. above, the number of known symbols that can be used is usually limited in order to avoid an extreme decrease in the transmission rate, so that it is difficult to obtain sufficient accuracy. For example, the central limit According to the theorem, it is difficult to achieve high accuracy with the conventional measurement method that uses only known symbols with limited power that improves 3 dB accuracy each time the number of measurement symbols is doubled. In order to measure the force, frame synchronization is necessary to identify the reception time of known symbols, so it takes time to start reception start force measurement, and measurement is not possible in a low SINR environment where synchronization is likely to be lost. There was a problem of becoming possible.
[0016] 上記 2.の方法は、仮判定値に誤りがあると測定値に大きな誤差を生じ、数値的安 定性が得られな 、と 、う問題があった。 [0016] The method of 2. above has a problem that if the provisional judgment value has an error, a large error occurs in the measured value, and numerical stability cannot be obtained.
[0017] 特に、 MIMO伝送に代表される SDMA方式では、 "コードの直交性"を利用せず に、伝送路パスの違いに基づいてユーザ信号を分離するので、残留干渉がより多く なり、受信信号の品質測定は CDMA以上に困難になると考えられる。 [0017] In particular, in the SDMA system represented by MIMO transmission, user signals are separated based on differences in transmission path paths without using "code orthogonality", so that there is more residual interference and reception. Signal quality measurement will be more difficult than CDMA.
[0018] 本発明の目的は、受信信号に残留干渉成分を多く含む場合にも、容易に、高精度 かつ安定な受信信号品質測定を行うことができる受信品質測定方法を提供すること である。 [0018] An object of the present invention is to provide a reception quality measurement method that can easily perform highly accurate and stable reception signal quality measurement even when the reception signal includes a large amount of residual interference components.
課題を解決するための手段 Means for solving the problem
[0019] 本発明の受信品質測定方法は、受信信号の信号分布の非ガウス性を測定し、非ガ ウス性が大きいほど前記受信信号の品質が良いと判定するようにする。 [0019] The reception quality measurement method of the present invention measures the non-Gaussianity of the signal distribution of the reception signal, and determines that the quality of the reception signal is better as the non-Gaussianity is larger.
発明の効果 The invention's effect
[0020] 本発明によれば、信号と残留干渉成分を分離することなく測定でき、かつ低レベル 信号であっても正しく品質判定を行ことができる、非ガウス性に基づいて、受信信号 の品質を測定するようにしたので、受信信号に残留干渉成分を多く含む場合にも、 容易に、高精度かつ安定な受信信号品質測定を行うことができるようになる。 [0020] According to the present invention, the quality of the received signal can be measured based on non-Gaussianity, which can be measured without separating the signal and the residual interference component, and can be correctly judged even with a low-level signal. Therefore, even when the received signal contains a lot of residual interference components, it becomes possible to easily perform highly accurate and stable received signal quality measurement.
図面の簡単な説明 Brief Description of Drawings
[0021] [図 1]従来の MIMO伝送システムの概念を示す図 [0021] [Fig. 1] Diagram showing the concept of a conventional MIMO transmission system
[図 2]従来の既知シンボルを用いた品質測定の説明に供する図 [Fig.2] Diagram for explaining quality measurement using conventional known symbols
[図 3]従来の仮判定による品質測定の説明に供する図 [Figure 3] Diagram for explaining quality measurement by conventional provisional judgment
[図 4]本発明による受信品質測定方法の適用例である実施の形態 1の説明に供する 図 FIG. 4 is a diagram for explaining the first embodiment which is an application example of the reception quality measurement method according to the present invention.
[図 5]本発明による受信品質測定方法を受信ダイバーシチ制御に用いた実施の形態
2の説明に供する図 FIG. 5 shows an embodiment in which the reception quality measurement method according to the present invention is used for reception diversity control. Figure for explanation of 2
[図 6]本発明による受信品質測定方法を送信ダイバーシチ制御に用いた実施の形態 3の説明に供する図 FIG. 6 is a diagram for explaining the third embodiment in which the reception quality measurement method according to the present invention is used for transmission diversity control.
[図 7]本発明による受信品質測定方法を MIMO伝送システムのリンクァダプテーショ ンに用いた実施の形態 4の説明に供する図 FIG. 7 is a diagram for explaining Embodiment 4 in which the reception quality measurement method according to the present invention is used for link adaptation of a MIMO transmission system.
[図 8]本発明による受信品質測定方法を MIMO伝送システムの送信電力制御に用 [FIG. 8] The reception quality measurement method according to the present invention is used for transmission power control of MIMO transmission systems.
V、た実施の形態 5の説明に供する図 V, diagram for explaining Embodiment 5
[図 9]Kurtosisの説明に供する図 [Fig.9] Diagram for explaining Kurtosis
[図 10]ネゲントロピーの説明に供する図 [Fig.10] Diagram for explaining Negentropy
発明を実施するための最良の形態 BEST MODE FOR CARRYING OUT THE INVENTION
[0022] 以下、本発明の実施の形態について図面を参照して詳細に説明する。 Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0023] (原理) [0023] (Principle)
本発明の特徴は、非ガウス分布に従う互いに独立な送信信号が混合すると中心極 限定理によってガウス分布に近づくことを利用し、レベルではなぐ "非ガウス性"を基 準に受信信号のみから直接品質を測定するものである。因みに、送信信号はコンス タレーシヨンなどから明らかなように非ガウス分布である。また、非ガウス性は、高次キ ュムラントゃネゲントロピーといった統計量で定量ィ匕できる。 The feature of the present invention is that when the transmission signals that are independent of each other according to the non-Gaussian distribution are mixed, the central limit theorem approximates the Gaussian distribution. Is to measure. Incidentally, the transmission signal has a non-Gaussian distribution as is clear from the constellation. Non-Gaussianity can be quantified with statistics such as higher-order cumulant negentropy.
[0024] 非ガウス性は、信号レベルと無関係な概念なので、低レベル信号であっても正しく 品質判定を行える。例えば残留干渉成分を含まない低レベル信号がある場合、受信 レベルで判定すると低品質ということになるが、非ガウス性で判定すると高品質になる[0024] Since non-Gaussianity is a concept unrelated to the signal level, quality judgment can be performed correctly even with a low-level signal. For example, if there is a low-level signal that does not contain residual interference components, it will be low quality if judged by the reception level, but it will become high quality if judged by non-Gaussianity.
。逆に残留干渉成分を多く含む高レベル信号についても同様である。従って、非ガウ ス性は残留干渉成分を含む受信信号に対しても有効な品質基準である。 . Conversely, the same applies to a high-level signal containing a lot of residual interference components. Therefore, non-gaussiness is an effective quality standard even for received signals containing residual interference components.
[0025] さらに非ガウス性は、信号と残留干渉成分を分離することなく測定できる統計量で ある。従って、測定には既知シンボルは不要で、全受信シンボルを用いた高精度な 測定を行うことができる。また測定にはフレーム同期も必要としないので、測定が容易 であり、受信開始と同時に測定を開始できるので引込み時間を短縮できる。 Furthermore, non-Gaussianity is a statistic that can be measured without separating the signal and the residual interference component. Therefore, no known symbols are required for measurement, and high-accuracy measurement using all received symbols can be performed. In addition, since frame synchronization is not required for measurement, measurement is easy, and measurement can be started at the same time as reception starts, so the pull-in time can be shortened.
[0026] また明らかに非ガウス性の測定では、仮判定による測定値の数値的不安定性は発 生しない。
[0027] 以上のように、受信信号品質を、非ガウス性を表す高次キュムラントゃネゲントロピ 一などの統計量で測定することにより、従来の課題を解決し、受信信号に残留干渉 成分を多く含む場合にも、容易に、高精度かつ安定な評価をすることができるように なる。 [0026] In addition, in the non-Gaussian measurement, there is no numerical instability of the measured value due to the provisional determination. [0027] As described above, by measuring the received signal quality with a statistic such as higher-order cumulant Negentropy that represents non-Gaussianity, the conventional problem is solved, and the received signal contains a large amount of residual interference components. Even in this case, it becomes possible to easily perform highly accurate and stable evaluation.
[0028] 因みに、本発明の発明者は、近年急速に注目されている Fast— ICA (Independent [0028] Incidentally, the inventor of the present invention has been rapidly attracting attention in recent years with Fast-ICA (Independent
Component Analysis)アルゴリズムに代表される、非ガウス性を指導原理とする独立 成分分析を参考にして、本発明に至った。 Fast-ICAでは、複数の源信号が互いに 独立な非ガウス分布に従うとしたとき、これらの混合信号は中心極限定理によってガ ウス分布に近づくことから、逆に分離信号の非ガウス性を最大にするように動作する。 つまり非ガウス性を表す量、分離性能を表す量として Kurtosis (尖度)の絶対値また はネゲントロピーと 、う統計量を用い、これらを最大化するように動作する。 The present invention has been achieved with reference to independent component analysis represented by a component analysis) algorithm, which is based on non-Gaussian principle. In Fast-ICA, when multiple source signals follow non-Gaussian distributions independent of each other, these mixed signals approach the Gaussian distribution by the central limit theorem, and conversely maximize the non-Gaussianity of the separated signal. To work. In other words, it uses the absolute value of Kurtosis (kurtosis) or negentropy as a quantity representing non-Gaussianity and a quantity representing separation performance, and operates to maximize these.
[0029] 移動通信の送信データは、明らかに非ガウス分布 (なぜなら離散分布だから)であり 、互いに独立と考えられ、同じ手法が適用可能である。つまり分離信号中に残留干 渉成分及び受信機雑音が多く含まれると非ガウス性が低下し、これらが少なければ 非ガウス性が増加する。 [0029] Transmission data of mobile communication is obviously non-Gaussian distribution (because it is a discrete distribution) and is considered to be independent from each other, and the same method can be applied. In other words, if there are many residual interference components and receiver noise in the separated signal, the non-Gaussianity will decrease, and if these are small, the non-Gaussianity will increase.
[0030] そこで、非ガウス性に基づ 、て、既知シンボル以外の全シンボルを用いた高精度か つ実用的な受信品質の測定方法を実現できる。 [0030] Therefore, based on non-Gaussianity, a highly accurate and practical measurement method of reception quality using all symbols other than known symbols can be realized.
[0031] (実施の形態 1) [Embodiment 1]
この実施の形態は、本発明を、回線品質の測定に用いることを提示するものである 。図 4において、試験移動機 100には、受信信号の非ガウス性を基準にして受信信 号の品質を測定 (評価)する非ガウス性測定器 103が設けられて 、る。非ガウス性測 定器 103は、アンテナ 101で受信され、受信機 102でダウンコンバートやアナログデ イジタル変換等の所定の無線受信処理が施された受信信号を入力する。 This embodiment presents that the present invention is used for measuring line quality. In FIG. 4, the test mobile device 100 is provided with a non-Gaussian measuring device 103 that measures (evaluates) the quality of the received signal based on the non-Gaussian property of the received signal. The non-Gaussian measuring device 103 receives a reception signal that is received by the antenna 101 and subjected to predetermined radio reception processing such as down-conversion and analog digital conversion by the receiver 102.
[0032] 非ガウス性測定器 103は、非ガウス性が高いほど受信品質が良いとする品質測定 結果を得るようになされて ヽる。 [0032] The non-Gaussianity measuring device 103 is configured to obtain a quality measurement result that the higher the non-Gaussianness is, the better the reception quality is.
[0033] セルラシステムの基地局の設置場所を選定する場合、試験基地局 200からの電波 を試験移動機 100で受信し、その受信信号の品質測定結果を蓄積することにより、 走行コースの伝搬状態を調べ、各地点での伝送特性を予想し、置局計画を策定する
。このような場合、従来は受信レベルを測定することで、受信品質の評価が行われて きた。 [0033] When selecting the installation location of the base station of the cellular system, the radio wave from the test base station 200 is received by the test mobile device 100, and the quality measurement result of the received signal is accumulated, so that the propagation state of the traveling course And estimate the transmission characteristics at each point and formulate a placement plan . In such cases, conventionally, reception quality has been evaluated by measuring the reception level.
[0034] ところが、複数基地局を用いた実験でのエリア境界付近や、他システムからの妨害 波が存在する走行コースでは、大きな干渉波が存在するため、単なる(干渉波を含む )受信レベルからは正しく伝送特性を予測することができず、受信信号と干渉波を分 離して測定する必要がある。このため従来であれば上述の仮判定による方法力、既 知シンボルを利用する方法を行う。しかし、前者は数値的不安定性力も測定には用 いるべきではなぐ後者の既知シンボルによる方法は測定に必須となるフレーム同期 性能に結果が大きく影響を受けることから信頼性を保っために装置が複雑ィ匕する上 に、無線伝送フォーマット毎に計測装置を用意する必要がある。 [0034] However, in the vicinity of an area boundary in an experiment using a plurality of base stations, or in a traveling course in which interference waves from other systems exist, there are large interference waves, so from a simple reception level (including interference waves) Cannot correctly predict the transmission characteristics, and it is necessary to measure the received signal and the interference wave separately. For this reason, conventionally, a method using the above-described provisional determination method and a known symbol is used. However, the former method should not use numerical instability force. The latter method using known symbols greatly affects the frame synchronization performance that is essential for the measurement, so the device is complicated to maintain reliability. In addition, it is necessary to prepare a measuring device for each wireless transmission format.
[0035] これに対して、本実施の形態にお!、ては、非ガウス性を用いて計測を行うようにした ので、干渉波の有無に無関係にフレーム同期性能に影響されること無ぐ高精度で 安定な結果を得ることができる。またフレームフォーマットに依存しない汎用性のある 計測器を実現できる。 [0035] In contrast, in this embodiment, since measurement is performed using non-Gaussianity, frame synchronization performance is not affected regardless of the presence or absence of interference waves. Highly accurate and stable results can be obtained. Also, a versatile measuring instrument that does not depend on the frame format can be realized.
[0036] なお、非ガウス性測定器 103を携帯端末に実装すれば、受信電解強度表示よりも より実際の受信品質に対応した表示を行うことができるようになる。 [0036] If the non-Gaussian measuring device 103 is mounted on a portable terminal, a display corresponding to the actual reception quality can be performed rather than the reception electrolysis strength display.
[0037] (実施の形態 2) [0037] (Embodiment 2)
この実施の形態は、本発明を、受信ダイバーシチの制御に適用することを提示する ものである。 This embodiment presents that the present invention is applied to reception diversity control.
[0038] 図 5を用いて、本実施の形態の受信ダイバーシチについて説明する。送信局 300 から送信された信号は、受信局 400の複数のアンテナ RxANT— 0〜RxANT— N 1で受信される。各アンテナ RxANT— 0〜RxANT— N— 1で受信された信号は 、各非ガウス性測定部 401— 0〜401— N— 1によって受信品質が測定される。すな わち、各非ガウス性測定部 401—0〜401—N—1は、受信信号の非ガウス性に基づ き、非ガウス性が高いほど受信品質が良いとする品質測定結果を得る。各非ガウス性 測定部 401— 0〜401— N— 1は、このようにして得た測定結果をダイバーシチ合成 部 402に送出する。ダイバーシチ合成部 402は、測定結果を基に、各アンテナ RxA NT— 0〜RxANT— N— 1で得られた受信信号をダイバーシチ合成する。
[0039] 従来の受信ダイバーシチでは、 1ストリームの信号を 1本のアンテナ力も送信し、こ れを複数のアンテナで受信し、受信アンテナでの受信レベルに応じてダイバーシチ 合成を行うことで、 SNRを改善して良好な受信特性を得るようになつている。さらに、 複数の送信機からの電波が到達するような大きな干渉波が存在する伝搬環境にお いては、単なる(干渉波を含む)受信レベルは受信品質を正しく表さないので、これを 元に制御するとダイバーシチの効果が得られなくなることを考慮して、上述の仮判定 による方法力、既知シンボルを利用する方法を行うことが一般的である。しかし、前者 は数値的不安定性力も測定には用いるべきではなぐ後者の既知シンボルによる方 法は測定に必須となるフレーム同期性能に結果が大きく影響を受けることから信頼性 を保っために装置が複雑ィ匕する上に、無線伝送フォーマット毎に受信ダイバーシチ 回路を用意する必要がある。 [0038] Reception diversity according to the present embodiment will be described with reference to FIG. A signal transmitted from the transmitting station 300 is received by a plurality of antennas RxANT-0 to RxANT-N1 of the receiving station 400. The reception quality of the signals received by the respective antennas RxANT-0 to RxANT-N-1 is measured by the respective non-Gaussian measuring units 401-0 to 401-N-1. In other words, each of the non-Gaussian measurement units 401-0 to 401-N-1 obtains a quality measurement result that the higher the non-Gaussian property, the better the reception quality, based on the non-Gaussian property of the received signal. . Each non-Gaussian measurement unit 401-0 to 401-N-1 sends the measurement result obtained in this way to diversity combining unit 402. Diversity combining section 402 diversity combines the received signals obtained by antennas RxANT-0 to RxANT-N-1 based on the measurement results. [0039] In conventional reception diversity, a single stream signal is transmitted even with one antenna, and this is received by multiple antennas, and diversity combining is performed according to the reception level at the reception antenna, thereby reducing the SNR. Improvements have been made to obtain good reception characteristics. Furthermore, in a propagation environment where there are large interference waves where radio waves from multiple transmitters arrive, simple reception levels (including interference waves) do not accurately represent the reception quality. In consideration of the fact that the diversity effect cannot be obtained if the control is performed, it is common to use the method based on the above-described provisional determination and a method using a known symbol. However, the former method should not be used for the measurement of numerical instability. The latter method using known symbols is greatly affected by the frame synchronization performance that is essential for the measurement, so the device is complicated to maintain reliability. In addition, it is necessary to prepare a receive diversity circuit for each wireless transmission format.
[0040] これに対して、本実施の形態においては、各受信アンテナ RxANT— 0〜RxANT —N—lで得られた信号の品質を非ガウス性を用いて測定し、それをダイバーシチ合 成の指標するようにしたので、干渉波の有無に無関係に、かつフレーム同期性能に 影響されること無ぐ高精度で安定な受信ダイバーシチ制御を実現することができる。 またフレームフォーマットに依存しない汎用性のある受信ダイバーシチを実現できる。 In contrast, in the present embodiment, the quality of the signal obtained by each of the receiving antennas RxANT—0 to RxANT —N—l is measured using non-Gaussianity, and this is used for diversity combining. Since the index is used, it is possible to realize highly accurate and stable reception diversity control regardless of the presence or absence of interference waves and without being affected by the frame synchronization performance. In addition, versatile reception diversity independent of the frame format can be realized.
[0041] (実施の形態 3) [Embodiment 3]
この実施の形態は、本発明を、送信ダイバーシチ制御に適用することを提示するも のである。具体的には、受信側で非ガウス性に基づいて受信信号の品質を高精度で 測定し、この測定結果に基づ!ヽて送信ダイバーシチの係数を高精度で設定する。 This embodiment presents that the present invention is applied to transmission diversity control. Specifically, the quality of the received signal is measured with high accuracy on the receiving side based on non-Gaussianity, and the coefficient of transmission diversity is set with high accuracy based on this measurement result.
[0042] 図 6を用いて、本実施の形態の送信ダイバーシチ制御にっ 、て説明する。送信局 500は、 1ストリームの信号を、重み付けコピー分岐部 501によって、送信アンテナ数 分コピーして増やし、かつ重み係数を掛けることにより、複数の送信アンテナ TxAN T— 0〜TxANT— M— 1分の送信信号を形成する。 [0042] The transmission diversity control according to the present embodiment will be described with reference to FIG. The transmitting station 500 copies a single stream signal by the number of transmission antennas by the weighting copy branching unit 501 and increases the number of transmission antennas, and multiplies them by a weighting coefficient, so that a plurality of transmission antennas TxAN T—0 to TxANT—M—1 minute The transmission signal is formed.
[0043] 受信局 600は、これらの混合信号を 1アンテナで受信する。チャネル推定部 601は 、既知シンボルの歪みに基づいてチャネル推定を行う。このチャネル推定値は、送信 装置 602を介して送信局 500に無線送信される。これにカ卩えて、受信局 600は、非 ガウス性測定部 603を有し、当該非ガウス性測定部 603によって受信信号の非ガウ
ス性を測定する。そして非ガウス性測定部 603は、受信信号の非ガウス性が所定の 閾値よりも低くなつたときのみ、送信装置 602にチャネル推定値を送信することを指 示する送信指示信号を送出する。 [0043] The receiving station 600 receives these mixed signals with one antenna. The channel estimation unit 601 performs channel estimation based on known symbol distortion. This channel estimation value is wirelessly transmitted to the transmission station 500 via the transmission device 602. In addition to this, the receiving station 600 has a non-Gaussian measuring unit 603, and the non-Gaussian measuring unit 603 receives a non-Gaussian signal. Measure the resistance. The non-Gaussianity measuring unit 603 transmits a transmission instruction signal instructing the transmission apparatus 602 to transmit a channel estimation value only when the non-Gaussianity of the received signal becomes lower than a predetermined threshold.
[0044] 送信局 500は、受信局 600からチャネル推定値がフィードバックされると、送信ダイ バーシチ制御部 502でチャネル推定値に基づいて送信ダイバーシチの重み係数を 変更して重み付けコピー分岐部 501に送出する。この送信ダイバーシチの重み係数 は、受信局 600において得たチャネル推定値を基に、受信アンテナ RxANTで良好 に受信できるように計算したものである。 [0044] When the channel estimation value is fed back from receiving station 600, transmission station 500 changes the transmission diversity weighting factor based on the channel estimation value in transmission diversity control section 502 and sends the result to weighting copy branching section 501. To do. The weighting factor of this transmission diversity is calculated based on the channel estimation value obtained at the receiving station 600 so that it can be satisfactorily received by the receiving antenna RxANT.
[0045] ところで、送信ダイバーシチ伝送では、チャネル推定精度が伝送特性に大きく影響 する。ところが、チャネル推定部 601で得られるチャネル推定値は数に制限のある既 知シンボルを用いて行うため、値が変動し、必ずしも既知シンボルを受信するたびに 更新するのが良いとは限らない。 By the way, in transmission diversity transmission, channel estimation accuracy greatly affects transmission characteristics. However, since the channel estimation value obtained by the channel estimation unit 601 is performed using known symbols with a limited number, the value fluctuates, and it is not always good to update every time a known symbol is received.
[0046] これを考慮して、本実施の形態では、チャネル推定値の品質を受信信号の非ガウ ス性を用いて判断し、品質が低下した時のみチャネル推定値を送信局 500にフィー ドバックするようにした。送信局 500は、フィードバックによる値更新が無い間は、現在 の値を保持する。 In consideration of this, in this embodiment, the quality of the channel estimation value is determined using the non-gaussiness of the received signal, and the channel estimation value is fed back to transmitting station 500 only when the quality is degraded. I tried to do it. The transmitting station 500 holds the current value while the value is not updated by feedback.
[0047] これにより、実質的に送信ダイバーシチの係数を変更する必要がある場合のみフィ ードバック情報を伝送するので、フィードバックに要する無線資源を節約できると共に 、フィードバック経路での伝送誤りを低減して安定した送信ダイバーシチを実現でき る。さらに非ガウス性を用いるため、干渉波の有無に無関係に、かつフレーム同期性 能に影響されること無ぐ高精度で安定な送信ダイバーシチ制御を実現することがで きる。 [0047] As a result, the feedback information is transmitted only when it is necessary to substantially change the coefficient of transmission diversity, so that radio resources required for feedback can be saved and transmission errors in the feedback path can be reduced and stable. Transmit diversity can be realized. In addition, since non-Gaussianity is used, highly accurate and stable transmission diversity control can be realized regardless of the presence or absence of interference waves and without being affected by the frame synchronization performance.
[0048] (実施の形態 4) [Embodiment 4]
この実施の形態は、本発明を、 MIMO伝送システムのリンクァダプテーシヨンに適 用することを提示するものである。 This embodiment proposes that the present invention is applied to link adaptation of a MIMO transmission system.
[0049] 図 7を用いて、本実施の形態のリンクァダプテーシヨンについて説明する。送信局 7 00は、 Mチャネルの送信データを、 MIMO誤り制御符号化部 701及び MIMO変調 部 702を介して、複数のアンテナ TxANT 0〜TxANT M— 1から送信する。
[0050] 受信局 800は、複数のアンテナ RxANT— 0〜RxANT— N— 1で受信した信号を MIMO信号分離部 801に入力する。 MIMO信号分離部 801は、チャネル推定を行 い、さらにこのチャネル推定値を用いて、空間フィルタバンク法、干渉キャンセラ法、 最尤判定法等の分離アルゴリズムを用いて、 M個の送信信号 X〜x に相当する [0049] The link adaptation of the present embodiment will be described with reference to FIG. Transmitting station 700 transmits M-channel transmission data from a plurality of antennas TxANT 0 to TxANT M−1 via MIMO error control encoding section 701 and MIMO modulation section 702. [0050] Receiving station 800 inputs signals received by a plurality of antennas RxANT-0 to RxANT-N-1 to MIMO signal demultiplexing section 801. MIMO signal demultiplexing section 801 performs channel estimation, and further uses this channel estimation value to generate M transmission signals X to X using separation algorithms such as a spatial filter bank method, an interference canceller method, and a maximum likelihood determination method. corresponds to x
0 M- 1 0 M- 1
M個の分離信号 z〜z を得る。 M個の分離信号 z〜z は、 MIMO誤り訂正復 Obtain M separated signals z-z. M separated signals z to z are used for MIMO error correction recovery.
0 M- 1 0 M- 1 0 M- 1 0 M- 1
号ィ匕部 802によって誤り訂正復号されて、 Mチャネル分の受信データとされる。これ に加えて、受信局 800は、各分離信号 z〜z の非ガウス性を測定する非ガウス性 Error correction decoding is performed by the signal key unit 802 to be received data for M channels. In addition to this, the receiving station 800 can measure non-Gaussianity of each separated signal z to z.
0 M- 1 0 M- 1
測定部 803— 0〜803— M— 1を有する。各非ガウス性測定部 803— 0〜803— M 1により得られた各分離信号 z〜z の品質測定結果は、送信局 700に送られる It has measuring units 803-0 to 803-M-1. The quality measurement results of the separated signals z to z obtained by the non-Gaussian measuring units 803-0 to 803-M 1 are sent to the transmitting station 700.
0 M- 1 0 M- 1
[0051] 送信局 700は、受信局 800から各分離信号 z〜z の品質測定結果を受け取ると [0051] When the transmitting station 700 receives the quality measurement results of the separated signals z to z from the receiving station 800,
0 M- 1 0 M- 1
、この各分離信号 z〜z の品質測定結果をストリーム毎 MCS (Modulation and Co The quality measurement result of each separated signal z to z is converted into MCS (Modulation and Co
0 M- 1 0 M- 1
ding Scheme)制御部 703に入力する。ストリーム毎 MCS制御部 703は、ストリーム毎 (分離信号毎)の品質に応じて、誤り訂正符号化率、変調多値数を制御することで、 ストリーム間での伝送特性のばらつきを低減する。具体的には、ストリーム毎 MCS制 御部 703は、 MIMO誤り制御符号ィ匕部 701及び MIMO変調部 702に制御信号を 送出することにより、各分離信号 z〜z に対応するストリームについての誤り訂正 ding Scheme) Input to control unit 703. The per-stream MCS control unit 703 controls the error correction coding rate and the modulation multi-level number according to the quality of each stream (each separated signal), thereby reducing variations in transmission characteristics between streams. Specifically, the per-stream MCS control unit 703 sends error signals to streams corresponding to the separated signals z to z by sending control signals to the MIMO error control code unit 701 and the MIMO modulation unit 702.
0 M- 1 0 M- 1
符号化率、変調多値数を、各分離信号 z〜z の The coding rate and the modulation multi-level number are set for each separated signal z to z.
0 M- 1 品質に応じて制御する。 0 M-1 Control according to quality.
[0052] 従来、これらの制御は、既知シンボルを利用した、あるいは仮判定による受信品質 測定に基づいて行われている力 本実施の形態においては、分離信号 z〜z の [0052] Conventionally, these controls are performed using known symbols or based on reception quality measurement by provisional determination. In this embodiment, the separated signals z to z
0 M- 1 非ガウス性を測定することで行うようにしたので、品質測定に多くのシンボルを利用で き、数値的安定性に優れるので、従来よりも高精度で安定なリンクァダプテーシヨンを 実現することができるよう〖こなる。 0 M- 1 Since it is done by measuring non-Gaussianity, many symbols can be used for quality measurement and it has excellent numerical stability, so the link adaptation is more accurate and stable than before. To be able to realize
[0053] また、ファイル転送やストリーム配信などのように特別高速伝送が必要な場合は、誤 り制御符号ィ匕部 701において、受信局 800から送られてきた非ガウス性測定結果に 基づいて、品質の良いストリームに並び替えて送信することもできる。 [0053] Also, when special high-speed transmission is required, such as file transfer or stream distribution, based on the non-Gaussian measurement result sent from the receiving station 800 in the error control code section 701, It can also be rearranged into a high-quality stream for transmission.
[0054] (実施の形態 5) [Embodiment 5]
この実施の形態は、本発明を、 MIMO伝送システムの送信電力制御に適用するこ
とを提示するちのである。 In this embodiment, the present invention is applied to transmission power control of a MIMO transmission system. It is the person who presents.
[0055] 図 7との対応部分に同一符号を付して示す図 8を用いて、本実施の形態の送信電 力制御について説明する。受信局 800で非ガウス性測定部 803— 0〜803— M— 1 によって各分離信号 z〜z の品質を測定し、その測定結果を送信局 900に送るこ [0055] Transmission power control according to the present embodiment will be described with reference to FIG. 8 in which parts corresponding to those in FIG. The quality of each separated signal z to z is measured by the non-Gaussian measuring unit 803—0 to 803—M—1 at the receiving station 800, and the measurement result is sent to the transmitting station 900.
0 M- 1 0 M- 1
とは、実施の形態 4と同様である。 Is the same as in the fourth embodiment.
[0056] 送信局 900は、受信局 800から各分離信号 z〜z の品質測定結果を受け取ると [0056] When the transmitting station 900 receives the quality measurement result of each separated signal z to z from the receiving station 800,
0 M- 1 0 M- 1
、この各分離信号 z〜z の品質測定結果を送信電力制御部 902に入力する。送 The quality measurement results of the separated signals z to z are input to the transmission power control unit 902. Sending
0 M- 1 0 M- 1
信電力制御部 902は、ストリーム毎 (分離信号毎)の品質に応じて、各送信無線回路 901— 0〜901— M— 1での送信電力を制御することで、各ストリームの所要伝送品 質を保ちながら、不要な電波の送出を低減する。具体的には、送信電力制御部 902 は、各送信無線回路 901— 0〜901—M— 1に送信電力制御信号を送出することに より、各分離信号 z〜z The transmission power control unit 902 controls the transmission power in each transmission radio circuit 901-0 to 901-M-1 according to the quality of each stream (each separated signal), so that the required transmission quality of each stream is To reduce the transmission of unnecessary radio waves. Specifically, the transmission power control unit 902 sends the transmission power control signals to the respective transmission radio circuits 901-0 to 901-M-1, so that the separated signals z to z are transmitted.
0 M- 1に対応するストリームについての送信電力を、各分離信号 z〜z の品質に応じて制御する。 The transmission power for the stream corresponding to 0 M-1 is controlled according to the quality of each separated signal z to z.
0 M- 1 0 M- 1
[0057] 従来、 CDMAシステムでは、各ストリームの既知シンボルを用いて測定した SINR に基づいた送信電力制御が行われているが、本実施の形態においては、分離信号 z 〜z の非ガウス性を測定することで行うようにしたので、品質測定に多くのシンポ [0057] Conventionally, in the CDMA system, transmission power control based on SINR measured using known symbols of each stream is performed. In this embodiment, the non-Gaussianity of the separated signals z to z is reduced. Since it is done by measuring, many symposiums are used for quality measurement.
0 M- 1 0 M- 1
ルを利用でき、数値的安定性に優れるので、高精度で安定な送信電力制御を実現 することがでさるよう〖こなる。 Can be used and has excellent numerical stability, so that it is possible to achieve highly accurate and stable transmission power control.
[0058] なお、本実施の形態では、一例として MIMO伝送における送信電力制御に本発明 の非ガウス性を基準とした品質測定方法を適用した場合について述べたが、 CDMIn the present embodiment, as an example, the case where the quality measurement method based on non-Gaussianity of the present invention is applied to transmission power control in MIMO transmission has been described.
Aにおける送信電力制御に本発明の非ガウス性を基準とした品質測定方法を適用し た場合にも、同様の効果を得ることができる。 The same effect can be obtained when the quality measurement method based on non-Gaussianity of the present invention is applied to the transmission power control in A.
[0059] (実施の形態 6) [Embodiment 6]
この実施の形態は、非ガウス性を測定する方法として、好適な測定方法を提示する ものである。具体的には、受信信号の高次キュムラント絶対値を非ガウス性の指標と することを提示する。 This embodiment presents a preferred measurement method as a method for measuring non-Gaussianity. Specifically, we present that the absolute value of the higher-order cumulant of the received signal is used as a non-Gaussian index.
[0060] 本実施の形態の非ガウス性測定方法は、受信信号に対して、次式に示す Kurtosi sと呼ばれる 4次キュムラント (尖度とも言う)を計算し、この絶対値が大き ヽ程非ガウス
性が強い、つまり信号品質 (SINR)が高いと判定する。 [0060] The non-Gaussianity measuring method of the present embodiment calculates a fourth-order cumulant called Kurtosi s (also referred to as Kurtosis) shown in the following equation with respect to the received signal, and the absolute value is large. Gauss The signal is strong, that is, the signal quality (SINR) is high.
[数 2] [Equation 2]
[0061] ここで、(2)式は、正確には電力で正規化した Kurtosisである。また Ε [ · ]は集合平 均を表す。この集合平均 Ε [ · ]は、実際によく行われるように時間平均に置換えて計 算するとよい。(2)式は、従来の既知シンボルを使った品質測定方法とは異なり、全 受信シンボルに対して実行するものなので、より高精度な品質測定結果を得ることが できる。 [0061] Here, the expression (2) is Kurtosis that is normalized by power. Ε [·] represents the average of the set. This set average Ε [·] should be calculated by replacing it with the time average as is often done in practice. Unlike the conventional quality measurement method using known symbols, equation (2) is executed for all received symbols, so a more accurate quality measurement result can be obtained.
[0062] なおガウス信号は 3次以上のキュムラントは理論的に 0なので、 Kurtosisに限らず、 3次以上の高次キュムラントを用いれば、同様の非ガウス性測定を行うことができる。 It should be noted that the third-order or higher-order cumulant is theoretically 0 for the Gaussian signal, so that not only Kurtosis but also the third-order or higher-order cumulant can be used to perform the same non-Gaussian measurement.
[0063] ここでキュムラントにっ 、て補足説明する。信号 Xの統計量で、 k次モーメント (積率 )とは、(3)式で表されるものであり、例えば 1次モーメントの平均 は (4)式となる。 [0063] Here, supplementary explanation will be given for cumulants. The statistic of signal X, kth moment (moment of moment), is expressed by equation (3). For example, the average of the first moment is given by equation (4).
[0064] [数 3] [0064] [Equation 3]
E^k |=f Xkp(X)dX ( 3 ) E ^ k | = f X k p (X) dX (3)
[0065] [数 4] μ =/X-p(X)dX ( 4 ) また、(5)式で表される、平均の周りの k次モーメント もよく用いられる。 [0065] [Equation 4] μ = / X-p (X) dX (4) In addition, the k-th moment around the mean expressed by equation (5) is often used.
[0066] 2次モーメントが分散 σ である。なお k次モーメント μ は、(6)式のように積率母関 数 M (t)をティラー展開した時の係数に現れる c
[数 6] [0066] The second moment is the variance σ. Note the k-th moment mu, appears at the coefficient when deployed tiller (6) Sekiritsu mother function number M (t) as equation c [Equation 6]
( 6 ) (6)
[0067] これに対して、 k次キュムラント K とは、(7)式のように、積率母関数 M (t)の対数を とったキュムラント母関数 K (t)をティラー展開した時の係数として得られる統計量で [0067] On the other hand, the k-th order cumulant K is the coefficient when the cumulant generating function K (t) that is the logarithm of the product moment generating function M (t) is Tiller-expanded as shown in Eq. (7). With the statistics obtained as
X X
ある。ここで、 4次キュムラントが Kurtosis (尖度)である。 is there. Here, the 4th order cumulant is Kurtosis.
[数 7] [Equation 7]
[0068] なおガウス分布では 3次以上のキュムラントが 0であることが知られている。 [0068] It is known that the 3rd-order or higher cumulant is 0 in the Gaussian distribution.
[0069] 4次キュムラントである Kurtosisは、図 9に示すように確率密度分布の尖り具合に応 じて値が変わる統計量である。つまりガウス分布では 0、それよりもスーパーガウシァ ンでは正値、逆にサブガウシアンでは負値となる。従って、 Kurtosisの絶対値は非ガ ウス性を図る尺度となるが、信号の 4乗演算を含むために雑音の混入等により 1サン プルでも異常な値が混入すると敏感に値が変化し、尺度としての頑健さに欠ける。し 力しながら Kurtosisには、(8)式に示すような便利な性質があるためよく用いられる。 [0069] Kurtosis, a fourth-order cumulant, is a statistic whose value changes according to the sharpness of the probability density distribution, as shown in FIG. In other words, it is 0 for the Gaussian distribution, positive values for Super Gaussian, and negative values for Sub-Gaussian. Therefore, the absolute value of Kurtosis is a measure for non-Gaussianity, but since it includes the fourth power of the signal, the value changes sensitively even if an abnormal value is mixed even in one sample due to noise mixing. Lacks robustness. However, Kurtosis is often used because of its convenient properties as shown in Equation (8).
[数 8] [Equation 8]
Kurt(x+y) = Kurt(x) + Kurt(y Kurt (x + y) = Kurt (x) + Kurt (y
Kurt(i3 x) 二 4 Kurtix) ( 8 ) Kurt (i3 x) 2 4 Kurtix) (8)
[0070] 本実施の形態で提示した高次キュムラント絶対値により非ガウス性を判断する方法 は、受信信号の品質測定に広く適用できる。例えば、 MIMO受信装置における分離 信号の品質を測定する場合に用いると、キュムラントの絶対値が大きい程非ガウス性 が強ぐうまく分離されている、つまり分離信号の品質 (SINR)が高いと判定すること ができる。
[0071] (実施の形態 7) [0070] The method of determining non-Gaussianity based on the higher-order cumulant absolute value presented in the present embodiment can be widely applied to quality measurement of received signals. For example, when measuring the quality of a separated signal in a MIMO receiver, it is determined that the higher the cumulant absolute value, the stronger the non-Gaussianity, that is, the separated signal quality (SINR) is high. be able to. (Embodiment 7)
この実施の形態は、非ガウス性を測定する方法として、好適な測定方法を提示する ものである。具体的には、受信信号のネゲントロピーを非ガウス性の指標とすることを 提示する。 This embodiment presents a preferred measurement method as a method for measuring non-Gaussianity. Specifically, we propose that the negentropy of the received signal be a non-Gaussian index.
[0072] 本実施の形態の非ガウス性測定方法は、受信信号に対して、次式に示す近似ネゲ ントロピーという近似統計量を計算し、この値が大きい程非ガウス性が強い、つまり信 号品質 (SINR)が高いと判定する。 [0072] The non-Gaussianity measuring method of the present embodiment calculates an approximate statistic called approximate negentropy represented by the following equation for the received signal, and the larger this value, the stronger the non-Gaussianity, that is, the signal Judged as high quality (SINR).
また、 k„,k,は以下のような正の定数である。 K „, k, is a positive constant as follows.
[0073] ここで、(9)式において、計算実行前に zは平均 0,分散 1に正規化されているものと する。また Ε[ · ]は集合平均を表す。この集合平均 Ε[ · ]は、実際によく行われるように 時間平均に置換えて計算するとよい。 [0073] Here, in equation (9), it is assumed that z is normalized to an average of 0 and a variance of 1 before execution of the calculation. Ε [·] represents the set average. This set average Ε [·] should be calculated by replacing it with the time average as is often done in practice.
[0074] 図 10は、(10)式に示す確率密度分布において、パラメータ μによって分布の形状 を変化させた時のネゲントロピーと、 2通りの条件で(9)式による近似ネゲントロピーを 表したものである。任意の に対して、どちらの条件でも(9)式はネゲントロピーの良 い近似になっている。 [0074] Fig. 10 shows the negentropy when the shape of the distribution is changed by the parameter μ in the probability density distribution shown in equation (10) and the approximate negentropy according to equation (9) under two conditions. is there. For any, Eq. (9) is a good approximation of negentropy under either condition.
[数 10] p(y)= β · Φ(γ)+(1— }2φ(2(Ύ - 1》 , ( 1 0 )
[0075] なお、(9)式の G (y)には G (y) =y3などを用いることができる力 受信信号 zの確 [ Equation 10] p (y) = β · Φ (γ) + (1—} 2φ (2 ( Ύ -1), (1 0) [0075] Note that G (y) = y 3 can be used for G (y) in equation (9).
0 0 0 0
率密度分布関数が偶関数であることが分力つて 、る場合は (移動通信ではこの条件 はほぼいつも成立つ)、(9)式の G (y)は省略できて、近似ネゲントロピーは、(11) If the rate density distribution function is an even function (if this condition is almost always satisfied in mobile communications), G (y) in Eq. (9) can be omitted and the approximate negentropy is ( 11)
0 0
式にて計算できる。 It can be calculated by the formula.
[数 11] j(z) oc (E{G(Z)}-E{G(V)})2 ' G(z>i偶関数 [Equation 11] j (z) oc (E {G (Z)}-E {G (V)}) 2 'G (z> i even function
1 1
ここで Vは正規分布 <^v)=^e 2に従うガウス信号, ζも平均 0, 分散 1に正規化されている。 Here, V is a Gaussian signal according to the normal distribution <^ v ) = ^ e 2 and ζ is also normalized to mean 0 and variance 1.
■42% ■ 42%
( 1 1 ) (1 1)
[0076] なお、このような偶関数 G (z)としては、(12)式のようなものが有効と言われている。 [0076] As such an even function G (z), it is said that the equation (12) is effective.
[数 12] [Equation 12]
G| z I二一 log cosh az , 1 < a≤ 2 G | z I 21 log cosh az, 1 <a≤ 2
_ _ _ _
G(z = - e 2 ( 1 2 ) G (z =-e 2 (1 2)
[0077] ここでネゲントロピーについて補足説明する。連続信号が持つエントロピー(平均情 報量)は(13)式のように定義されていて、信号がガウス分布の時に最大値となること が理論的に証明されている。 [0077] Here, supplementary explanation of negentropy will be given. The entropy (average amount of information) that a continuous signal has is defined as in Eq. (13), and it is theoretically proven that the maximum value is obtained when the signal is Gaussian.
[数 13] [Equation 13]
H(z) = -/p(z}logp(z)dz ( 1 3 ) H (z) =-/ p (z} logp (z) dz (1 3)
[0078] そこで、このことを利用して(14)式のように信号がガウス分布の時に 0、それ以外で は正値となるネゲントロピーという量が考え出された。ネゲントロピーが大きいというこ とは zの非ガウス性が大きいということであるから、非ガウス性の尺度として使え、異常 値に対する感度も低く頑強である。 [0078] Therefore, using this, a quantity called negentropy that is 0 when the signal has a Gaussian distribution and a positive value otherwise is devised as shown in equation (14). A large negentropy means that the non-Gaussian property of z is large, so it can be used as a measure of non-Gaussian property, and it has low sensitivity and robustness to outliers.
[数 14]
¾auSSは平均と分散が2と等しいガウス信号
[Equation 14] ¾au SS is a Gaussian signal with mean and variance equal to 2.
しかしながら、ネゲントロピーを計算するために信号の確率密度関数 p (y )を推定す る必要があり、このまま計算するのは演算量が膨大で実用的ではなぐ近似が必要で ある。ネゲントロピー近似法の一つは、以下の多項式近似による方法である。 However, in order to calculate negentropy, it is necessary to estimate the probability density function p (y) of the signal, and calculating as it is requires an enormous approximation and impractical approximation. One of the Negentropy approximation methods is a method based on the following polynomial approximation.
[0080] 但しこの方法は、右辺第 2項に kurtosisを含むため安定性に乏しぐ図 10の破線 で示したように分布の形によっては大きな近似誤差が生ずる。 [0080] However, this method includes a kurtosis in the second term on the right side, so that a large approximation error occurs depending on the shape of the distribution as shown by the broken line in FIG.
[0081] もう一つの方法としてスペクトル推定などで古くから応用されている最大エントロピー 法(以下 MEMと記述する)の概念を応用した方法がある。 MEMは、いくつかの観測 関数 G (z) , G (z) ,…を用いてランダム信号 zを観測し、その観測値を満たし、かつ [0081] As another method, there is a method that applies the concept of the maximum entropy method (hereinafter referred to as MEM) that has been applied for a long time in spectrum estimation and the like. MEM observes a random signal z using several observation functions G (z), G (z), ..., satisfies the observations, and
0 1 0 1
その信号のエントロピーが最大になるような分布 (言い換えると観測値以外の情報は 全く用いずに考え得る分布)を Zの分布の推定値とすると 、うものである。 The distribution that maximizes the entropy of the signal (in other words, a distribution that can be considered without using any information other than the observed value) is the estimated value of the Z distribution.
[0082] これを適用して導かれた式は、 zの分布は H (z)を最大にする分布、おそらくガウス 分布に近い形の分布と考え、ネゲントロピーの下限値を推定したものである。このた め図 10では近似値は常に真値より小さくなつている力 安定して良い近似になって いるのはすでに述べた通りである。 [0082] The formula derived by applying this assumes that the distribution of z is a distribution that maximizes H (z), probably a distribution close to a Gaussian distribution, and estimates the lower limit of negentropy. For this reason, in Fig. 10, the approximate value is always smaller than the true value.
[0083] 本実施の形態で提示したネゲントロピーにより非ガウス性を判断する方法は、受信 信号の品質測定に広く適用できる。例えば、 MIMO受信装置における分離信号の 品質を測定する場合に用いると、ネゲントロピーの値が大きい程非ガウス性が強ぐう まく分離されている、つまり分離信号の品質 (SINR)が高いと判定することができる。 産業上の利用可能性 [0083] The method of determining non-Gaussianity by negentropy presented in this embodiment can be widely applied to the quality measurement of received signals. For example, when measuring the quality of the separated signal in a MIMO receiver, it is determined that the non-Gaussianity is more strongly separated as the negentropy value is larger, that is, the separated signal quality (SINR) is higher. Can do. Industrial applicability
[0084] 本発明は、受信信号に残留干渉成分を多く含む場合にも、容易に、高精度かつ安 定な受信信号品質測定を行うことができると 、つた効果を有し、受信品質の計測装 置、受信ダイバーシチ装置、送信ダイバーシチ制御、 MIMO伝送システムによるリン
クァダブテーシヨン、送信電力制御、パス品質測定等に適用して有用である。
[0084] The present invention is advantageous in that it is possible to easily perform highly accurate and stable reception signal quality measurement even when the reception signal includes a large amount of residual interference components. Device, receive diversity device, transmit diversity control, MIMO transmission system link It is useful when applied to quadration, transmission power control, path quality measurement, and the like.
Claims
[1] 受信信号の信号分布の非ガウス性を測定し、非ガウス性が大き!、ほど前記受信信 号の品質が良いと判定する [1] Measure the non-Gaussianity of the signal distribution of the received signal, and determine that the quality of the received signal is better as the non-Gaussianity is larger!
受信品質測定方法。 Reception quality measurement method.
[2] 前記非ガウス性を、前記受信信号の高次キュムラント絶対値に基づ!、て測定する 請求項 1に記載の受信品質測定方法。 [2] The reception quality measurement method according to claim 1, wherein the non-Gaussian property is measured based on a high-order cumulant absolute value of the reception signal.
[3] 前記非ガウス性を、ネゲントロピーに基づ 、て測定する [3] Measure the non-Gaussianity based on negentropy
請求項 1に記載の受信品質測定方法。
The reception quality measurement method according to claim 1.
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