JP4437811B2 - Line quality measuring device - Google Patents

Description

  The present invention relates to a channel quality measuring apparatus for a receiver used in a digital wireless communication system such as satellite communication, mobile communication, and mobile satellite communication.

  FIG. 10 is a block diagram showing a conventional line quality measuring apparatus that realizes line quality measurement as shown in Non-Patent Document 1 below.

  In FIG. 10, a conventional channel quality measuring apparatus detects and demodulates a phase-modulated received signal and outputs it as a signal point for obtaining phase information at a decision point such as a Nyquist point; A phase region determination unit 102 that determines which phase region the signal point output from the detection unit 101, that is, demodulated phase information corresponds to among a plurality of different phase regions set in advance, and each phase A counting unit 103 that counts the number of signal points that have entered the area, and a phase distribution table that indicates the relationship between the phase distribution probability of each phase area obtained by actual measurement, simulation, theoretical calculation, and the value that represents the line quality The likelihood for each phase distribution model of the phase distribution obtained by the phase distribution table storage unit 106 and the count value of the counting unit 103 is calculated to obtain the maximum likelihood. Phase distribution to identify the phase distribution of the model, and includes a likelihood calculation unit 107 outputs the estimated value showing the line quality of the transmission path corresponding to the identified phase distribution model, the.

  In addition, the counting unit 103 includes a plurality of region counting units 103-1, 103-2,... That count signal points output from the detection unit 101 for each of a plurality of different phase regions set in advance. . . 103-M. Here, M indicates the number of phase regions.

FIG. 11A is a signal space diagram showing a phase distribution determination region when the detection unit 101 modulates a QPSK modulated signal. In FIG. 11 (a), among the phases (π / 4, 3π / 4, −π / 4, −3π / 4) demodulated by the detector 101, the phase closest to the phase π / 4 is shown. the region and R _1, the R _2, R _3, R ₄ from the phase region R ₁ as a phase region adjacent to the order, the representative of the determination area of the phase distribution divided into phase regions of equal width of four kinds 1 Shows the quadrant. The phases 3π / 4, −π / 4, and −3π / 4 are similarly expressed in the second quadrant, the fourth quadrant, and the third quadrant, respectively.

Therefore, assuming that the signal point output from the detector 101 when the received signal indicating the phase information π / 4 passes through an ideal transmission path is S ₁ , the phase is as shown in FIG. 11 (a). center line of the region R _1, that is, be located on a line indicating the first quadrant of the phase [pi / 4. However, the thermal noise and fading is applied to the transmission path, the original phase information [pi / 4 signal points should exhibit is shifted from a line indicating the phase [pi / 4 as S _2. In particular, if the phase shifts by more than π / 4 from the original signal point, the quadrant of the signal point changes, resulting in a bit error.

That is, in FIG. 11A, in the order of the phase regions R ₁ , R ₂ , R ₃ , R ₄ , the bit error rate (BER) and the signal-to-noise power ratio (noise power with respect to the signal power of 1 bit of information: Eb / No) is considered to be high, and the bit error rate and the signal-to-noise power ratio can be estimated by measuring the probability that the signal point enters these phase regions (hereinafter referred to as phase distribution probability).

  For example, the signal points output in the detection unit 101 are sequentially received using a table indicating the relationship between each phase distribution probability and the bit error rate or signal-to-noise power ratio in advance. The bit error rate or signal-to-noise power ratio of the signal point of the received signal can be specified and obtained, and this numerical value (estimated value) can be regarded as an estimated value indicating the channel quality of the transmission path.

In the case of the example described above, the counting unit 103 corresponds to the phase regions R ₁ , R ₂ , R ₃ , R ₄ , and the region counting unit 103-1 that counts the number of signal points corresponding to each phase region, 103-2, 103-3, and 103-4 (that is, M = 4). Here, as shown in FIG. 11A, if a signal point S ₁ is transmitted as a transmission signal and is received at the signal point S ₂ in the detection unit 101, the signal point S ₁ is received by the phase region determination unit 102. ₂ is determined to enter the phase region R ₂ , and is counted by the region counting unit 103-2 in the phase region R ₂ .

  As described above, the phase regions are determined for all the received signals received by the detection unit 101 within the predetermined measurement period, and the respective phase regions are counted, and the phases as shown in FIG. Distribution is required. By using this phase distribution, the above-described phase distribution probability is derived.

  Here, for example, it can be considered that a communicating communicator is communicating through a fading transmission line and a stationary communicator is communicating through a Gaussian transmission line, but the phase distribution probability and the bit error rate or signal-to-noise are considered. The relationship with the power ratio usually varies depending on the transmission path state during communication, and there is a problem that an accurate bit error rate or signal-to-noise power ratio cannot be estimated simply by measuring the phase distribution probability. become.

  Therefore, the correlation between phase distribution probability and line quality (bit error rate or signal-to-noise power ratio, etc.) for each of several typical transmission line models such as fading transmission lines and Gaussian transmission lines, based on simulations and measured data. A phase distribution table is generated, and this phase distribution table is stored in the phase distribution table storage unit 106.

  Actually, the phase distribution table has a table showing the relationship between the phase distribution probability of each phase region obtained by actual measurement, simulation, theoretical calculation, or the like and a value representing the line quality.

  Then, the likelihood calculating unit 107 calculates the likelihood of each phase distribution model of the phase distribution obtained from the counting result of the counting unit 103 with reference to the phase distribution table stored in the phase distribution table storage unit 106. Thus, the phase distribution model that maximizes the posterior probability, that is, the maximum likelihood phase distribution model is specified, and an estimated value indicating the channel quality corresponding to the specified phase distribution model is output. At this time, the likelihood L (k) of the phase distribution model k is obtained as in the following equation (1).

Here, the count values for the four phase regions are u _{1 to} u ₄ , the logarithm of the value for each phase region of the phase distribution model k in the phase distribution table is v _1k to v _4k, and the occurrence probability of the phase distribution model k The logarithm of is λk.

“A Scheme for High Performance Real-Time BER Measurement”, IEEE Trans. On Comm., Vol.40, No.10, Oct.1992 pp.1574-1576

  However, the conventional line quality measurement apparatus measures quality by dividing a certain period of continuous data, and the estimation accuracy of the line quality is determined by the measurement period. Therefore, a low signal-to-noise power ratio is sufficient. In order to obtain accuracy, it is necessary to make the measurement period sufficiently long. However, when applied to an actual system, the transmission path may change over time, or data may be sent in burst units as in TDMA (Time Division Multiple Access) communication. When the transmission path fluctuates over time in this way, if the measurement period becomes too long, the tracking accuracy of the transmission path will deteriorate and the estimation accuracy will not increase. In such data transmission / reception in burst units, when the line quality is measured in burst units, if the burst size is short, the estimation accuracy decreases.

  The present invention has been made in view of the above, and uses a weighted averaging process to provide a channel quality measuring apparatus with high estimation accuracy even in an actual system in which a transmission path fluctuates in time. An object of the present invention is to provide a line quality measuring apparatus that realizes higher-accuracy measurement in a shorter measurement period by measuring the line quality using not only the phase but also the amplitude.

  In order to solve the above-described problems and achieve the object, the present invention provides detection means for detecting and demodulating a received signal, and a plurality of different amplitude regions in which output signal points output by the detection means are set in advance. An amplitude region determination unit that determines which amplitude region corresponds, a counting unit that counts the number of output signal points corresponding to the amplitude region in the amplitude region determination unit, and an actual measurement Amplitude table storage means for storing a table showing the relationship between the amplitude distribution probability of each amplitude area obtained by simulation, simulation, theoretical calculation, etc. and the value indicating the line quality for each of a plurality of different amplitude distribution models, and the amplitude distribution Using the amplitude distribution table stored in the table storage means, the likelihood of the amplitude distribution of the received signal indicated by the count value for each amplitude region counted in the counting means. For each amplitude distribution model, the maximum likelihood amplitude distribution model is specified, and the channel quality corresponding to the specified amplitude distribution model is output as an estimated value representing the channel quality of the transmission path of the received signal. And a likelihood calculating means.

  According to this invention, the amplitude region determining means determines in which amplitude region the output signal point output by the detecting means is, and the counting means determines the number of output signal points in the amplitude region for each amplitude region. The likelihood calculation means counts the likelihood of the amplitude distribution of the received signal, which is the calculation result of the counting means, using the amplitude distribution table stored in the amplitude distribution table storage means. The maximum likelihood amplitude distribution model is specified by calculating every time, and the channel quality value corresponding to the specified amplitude distribution model is output as the channel quality estimation value of the transmission path. When receiving data or when receiving discontinuous data in units of bursts, the channel quality of the transmission path can be estimated by measuring the amplitude of the received signal.

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

Embodiment 1 FIG.
FIG. 1 is a block diagram of a schematic configuration of the line quality measuring apparatus according to the first embodiment. In addition, the same code | symbol is attached | subjected to the part which is common in FIG. 10, and the description is abbreviate | omitted. In the line quality measuring apparatus according to the first embodiment shown in FIG. 1, the weighted average value calculating unit 105 that calculates the weighted average value from the count result output from the counting unit 103 and the weighted average value calculating unit 105 perform the calculation. And a weighted average value storage unit 104 for storing the weighted average value, which is different from the conventional line quality measuring apparatus shown in FIG.

Here, as an example, it is assumed that TDMA communication with a modulation scheme of QPSK is performed, and the phase region is divided into four regions R ₁ , R ₂ , R ₃ , and R ₄ as shown in FIG. A case where the line quality is measured for each will be described.

Figure 2 is an explanatory diagram showing a channel quality measuring burst of burst size T _b in the measurement time period T _p. In FIG. 2, firstly, the first transmission signal of the burst to be measured is the signal point S ₁ shown in FIG. 11, and this signal point is received by the detection unit 101 at the signal point S _2. This signal point S ₂ is determined by the region determination unit 102 to correspond to the phase region R ₂ and is counted by the region counting unit 103-2 in the region R ₂ . The counting unit 103 determines the phase distribution of the reception signal points of the burst at the time nT _p by determining and counting the phase region corresponding to the reception signal points for all transmission signals of the burst size T _b by the same procedure. Calculate.

The weighted average value calculation unit 105 is weighted averaged at the time (n−1) T _p stored in the weighted average value storage unit 104, that is, weighted averaged by the weighted average value calculation unit 105 last time. The calculated phase distribution is weighted and averaged to the phase distribution at time nT _p which is the output of the counting unit 103. Specifically, the weighted average value calculation unit 105 sets the count value of the phase distribution of the phase region R ₁ at time nT _p as u _j [nT _p ] and the forgetting factor α (0 ≦ α ≦ 1), The count value U _j [nT _p ] after weighted averaging is calculated by the following equation (2).
U _j [nT _p ] = u _j [nT _p ] + α U _j [(n−1) T _p ] (2)

Subsequently, the phase distribution after weighted averaging at time nT _p that is the output of the weighted average value calculation unit 105 is stored in the weighted average value storage unit 104. This is to be used as the previous weighted average value, that is, the weighted average value of the phase distribution at time (n + 1) T _{p in} the next weighted average value calculation.

The likelihood calculating unit 107 receives the weighted averaged phase distribution output from the weighted average value calculating unit 105, refers to the phase distribution table stored in the phase distribution table storage unit 106, and determines each phase distribution. Computes the likelihood of the weighted averaged phase distribution for each model to identify the phase distribution model that maximizes the posterior probability, that is, the maximum likelihood phase distribution model, and the line corresponding to the identified phase distribution model The quality value is output as an estimate of the channel quality of the transmission path. At this time, the likelihood L (k) of the phase distribution model k is obtained by the following equation (3) using the count value U _j [nT _p ] after weighted averaging.

Here, the count values for the four phase regions are u _{1 to} u ₄ , the logarithm of the value for each phase region of the phase distribution model k in the phase distribution table is v _1k to v _4k, and the occurrence probability of the phase distribution model k The logarithm of is λ _k .

  FIG. 3 is a graph for explaining the matching of the signal-to-noise power ratio (Eb / No) output as an estimated value with the actual Eb / No. In FIG. 3, the modulation scheme is QPSK, the number of phase regions is 4, and there are phase distribution tables for two transmission line models of a Gaussian transmission line and a Rician fading transmission line (Rice factor 7 dB, Doppler frequency 200 Hz). It is the estimation result of the signal-to-noise power ratio (Eb / No) by computer simulation in the case. From FIG. 3, the estimated value calculated by the line quality measuring apparatus according to the present invention is more consistent with the actual Eb / No than the estimated value calculated in the conventional line quality measuring apparatus, and the line quality is It can be seen that is estimated correctly.

As described above, according to the line quality measuring apparatus according to the first embodiment, as shown in FIG. 2, when the conventional line quality measuring apparatus tries to increase the measurement accuracy of the line quality, the continuous wave , The measurement period T _c represented by times nT _c to (n + 1) nT _c needs to be lengthened, whereas the measurement period T _p represented by times nT _p to (n + 1) nT _p is required. Since the weighted average value calculation unit 105 and the weighted average value storage unit 104 are provided, the measurement results of the past signal points can be accumulated by weighted averaging of the signal point count values. It can be included, and it is possible to measure the line quality with high accuracy.

  Also, when the transmission path fluctuates with time, especially when performing discontinuous data transmission and reception in units of bursts, it is easy to accurately measure line quality for each burst even if the burst size is small. It becomes.

Embodiment 2. FIG.
Next, a line quality measuring apparatus according to the second embodiment will be described. FIG. 4 is a block diagram of a schematic configuration of the line quality measuring apparatus according to the second embodiment. In addition, the same code | symbol is attached | subjected to the part which is common in FIG. 10, and the description is abbreviate | omitted. In the line quality measuring apparatus according to the second embodiment shown in FIG. 4, the amplitude region determining unit 108 and the phase distribution table storing unit 106 are replaced with the amplitude region determining unit 108 and the amplitude distribution table storing unit instead of the phase region determining unit 102 of FIG. Is different from the conventional line quality measuring apparatus shown in FIG.

FIG. 5 is a signal space diagram showing a determination region of amplitude distribution when the detection unit 101 modulates a QPSK modulation signal. FIG. 5 particularly shows a determination area of the amplitude of the signal point demodulated as phase information π / 4 in the detection unit 101. The amplitude area (R ₁ , R ₁ , Reference is made to determine which of R ₂ and R ₃ ) is applicable. For signal points demodulated as phase information 3π / 4, −π / 4, and −3π / 4, similar amplitude determination regions are respectively represented in the second quadrant, the fourth quadrant, and the third quadrant.

Here, when the signal point output from the detection unit 101 when the received signal indicating the phase information π / 4 passes through the ideal transmission path is S ₁ , the signal point S ₁ is shown in FIG. as shown, it shall be located on the two borders of the amplitude domain R _1. That is, in FIG. 5, the bit error rate and the signal-to-noise power ratio are considered to be higher in the order of the amplitude regions R ₁ , R ₂ , and R ₃ . In this case, the counting unit 103 corresponds to the amplitude regions R ₁ , R ₂ , and R _3, and region counting units 103-1, 103-2, and 103-that count the number of signal points corresponding to the respective phase regions. 3 (ie, M = 3). Here, as shown in FIG. 5, the signal points S1 transmitted as a transmission signal, when it is received at the signal point S ₂ in the detection unit 101, this signal point S ₂ amplitude region by the amplitude area determination unit 108 It is determined to enter R ₂ , and the area is counted by the area counting unit 103-2 in the amplitude area R ₂ .

  As described above, the amplitude distribution is obtained by determining the amplitude region for all the received signals received by the detection unit 101 within the predetermined measurement period and performing the counting for each amplitude region. By using this amplitude distribution, an amplitude distribution probability similar to the above-described phase distribution probability is derived.

  Similarly to the phase distribution table storage unit 106 described above, the amplitude distribution table storage unit 109 stores an amplitude distribution probability and a line quality for each of several typical transmission line models such as a fading transmission line and a Gaussian transmission line. An amplitude distribution table showing the correspondence relationship is stored. Here, as in the case of the phase distribution table, the amplitude distribution table actually has a table showing the relationship between each amplitude distribution probability obtained by actual measurement, simulation, theoretical calculation, etc. and a value representing the line quality. ing.

  Then, the likelihood calculating unit 107 refers to the amplitude distribution table stored in the amplitude distribution table storage unit 109, and weights the likelihood for each amplitude distribution model of the amplitude distribution obtained from the counting result of the counting unit 103 as described above. Calculate the averaged count value using each formula to identify the maximum likelihood amplitude distribution model, and use the channel quality value corresponding to the identified amplitude distribution model to estimate the channel quality of the transmission path. Output as.

  As described above, the line quality measuring apparatus according to the second embodiment includes the amplitude region determination unit 108 and the amplitude distribution table storage unit 109, so that it is transmitted as a continuous wave as shown in FIG. When receiving received signals or when receiving discontinuous data in units of bursts, it is possible to estimate the line quality of the transmission path with respect to the strength of the received signal, that is, by measuring the amplitude of the received signal It becomes.

  The weighted average value calculation unit 105 and the weighted average value storage unit 104 described in the first embodiment are inserted between the counting unit 103 and the likelihood calculation unit 107, and the likelihood calculation unit 107 performs weighted averaging. By obtaining the amplitude distribution using the subsequent count value, the same effect as in the first embodiment can be obtained.

Embodiment 3 FIG.
Next, a line quality measuring apparatus according to the third embodiment will be described. FIG. 6 is a block diagram of a schematic configuration of the line quality measuring apparatus according to the third embodiment. In addition, the same code | symbol is attached | subjected to the part which is common in FIG. 10, and the description is abbreviate | omitted. In the line quality measuring apparatus according to the third embodiment shown in FIG. 6, the phase amplitude distribution determining unit 111 in place of the phase region determining unit 102 in FIG. 10 and the phase amplitude distribution in place of the phase distribution table storage unit 106 are used. The table storage unit 112 is different from the conventional line quality measuring apparatus shown in FIG.

FIG. 7 is a signal space diagram showing a phase amplitude distribution determination region when the detection unit 101 modulates a QPSK modulated signal. Here, the phase amplitude distribution indicates a distribution of signal points obtained by combining the phase distribution and the amplitude distribution in the first and second embodiments on the phase amplitude plane. FIG. 7 shows the determination area of the amplitude of the signal point demodulated as phase information π / 4 in the detection unit 101, and is divided into four types in the same manner as the phase region in which the signal point is divided into four types. This is referred to in order to determine which of the four types of phase amplitude regions R ₁ , R ₂ , R ₃ , and R ₄ that indicate a common region with the amplitude region that is applied.

  For signal points demodulated as phase information 3π / 4, −π / 4, and −3π / 4, the same phase amplitude determination areas are respectively expressed in the second quadrant, the fourth quadrant, and the third quadrant. .

Here, when the signal point output from the detector 101 when the received signal indicating the phase information π / 4 passes through an ideal transmission path is S ₁ , the signal point S ₁ is shown in FIG. As shown, it is assumed to be located at the center of the two phase amplitude regions R ₁ . That is, in FIG. 7, it is considered that the bit error rate and the signal-to-noise power ratio are higher in the order of the phase amplitude regions R ₁ , R ₂ , R ₃ , R ₄ .

In this case, the counting unit 103 corresponds to the phase amplitude regions R ₁ , R ₂ , R ₃ , and R _4, and region counting units 103-1 and 103 that count the number of signal points corresponding to the respective phase amplitude regions. -2, 103-3, and 103-4 (that is, M = 4). Here, as shown in FIG. 7, the signal point S ₁ is transmitted as a transmission signal, when it is received at the signal point S ₂ in the detection unit 101, the signal point S ₂ by the phase amplitude region determination unit 111 It is determined that the phase amplitude region R ₂ is entered, and is counted by the region counting unit 103-2 in the phase amplitude region R ₂ .

  As described above, the phase amplitude distribution is obtained by determining the phase amplitude region for all the received signals received by the detection unit 101 within a predetermined measurement period and performing the counting for each phase amplitude region. By using this phase amplitude distribution, a phase amplitude distribution probability similar to the above-described phase distribution probability is derived.

  Similarly to the phase distribution table storage unit 106 described above, the phase amplitude distribution table storage unit 112 includes a phase amplitude distribution probability and a phase amplitude distribution probability for each of several representative transmission line models such as a fading transmission line and a Gaussian transmission line. A phase amplitude distribution table indicating the correspondence relationship of the line quality is stored.

  Here, as in the case of the phase distribution table, in practice, the phase amplitude distribution table is a table showing the relationship between each phase amplitude distribution probability obtained by actual measurement, simulation, theoretical calculation, etc. and a value representing the line quality. Have.

  Then, the likelihood calculation unit 107 refers to the phase amplitude distribution table stored in the phase amplitude distribution table storage unit 112, and the likelihood for each phase amplitude distribution model of the phase amplitude distribution obtained from the counting result of the counting unit 103. Is calculated using the above-described mathematical formula for calculating the count value after weighted averaging, and the maximum likelihood phase amplitude distribution model is specified, and the channel quality value corresponding to the specified phase amplitude distribution model is determined for the transmission line. Is output as an estimate of the channel quality.

  As described above, the line quality measurement apparatus according to the third embodiment includes the phase amplitude region determination unit 111 and the phase amplitude distribution table storage unit 112, and therefore receives a signal transmitted as a continuous wave. When receiving discontinuous or bursty data, it is possible to measure the bit error rate and signal-to-noise power ratio caused by both the phase information shift and the received signal strength change. Can be estimated with higher accuracy.

  The weighted average value calculation unit 105 and the weighted average value storage unit 104 described in the first embodiment are inserted between the counting unit 103 and the likelihood calculation unit 107, and the likelihood calculation unit 107 performs weighted averaging. By obtaining the phase amplitude distribution using the subsequent count value, the same effect as in the first embodiment can be obtained.

Embodiment 4 FIG.
Next, a line quality measuring apparatus according to the fourth embodiment will be described. FIG. 8 is a block diagram of a schematic configuration of the line quality measuring apparatus according to the fourth embodiment. Parts common to those in FIGS. 1 and 4 are denoted by the same reference numerals and description thereof is omitted.

  In the channel quality measuring apparatus according to the fourth embodiment shown in FIG. 8, a system comprising phase region determining unit 102, counting unit 103, likelihood calculating unit 107, and phase distribution table storing unit 106 of the conventional channel quality measuring apparatus. And a system consisting of the amplitude region determining unit 108, the counting unit 103, the likelihood calculating unit 107, and the amplitude distribution table storage unit 109 of the line quality measuring apparatus according to the second embodiment in parallel, and an estimated value By providing the selection unit 110, it is possible to select the estimated value calculated by the phase region determination in the former system or the estimated value calculated by the amplitude region determination in the latter system and select the line This is output as an estimated value indicating quality.

  In FIG. 8, the counting unit 103 in the former system is the first counting unit 103a, the likelihood calculating unit 107 is the first likelihood calculating unit 107a, and the counting unit 103 in the latter system is described above. Is represented as a second counting unit 103b, and the likelihood calculating unit 107 is represented as a second likelihood calculating unit 107b.

Therefore, in the channel quality measurement apparatus according to the fourth embodiment, the signal points demodulated by the detection unit 101 (including both phase information and amplitude information) are simultaneously transmitted to the phase region determination unit 102 and the amplitude region determination unit 108. Entered. Then, as in the conventional line quality measuring apparatus, the phase region determination unit 102 and the first counting unit 103a perform phase region determination for all received signals received by the detection unit 101 and each phase. The phase distribution is obtained by counting for each area, and the first likelihood calculating unit 107a uses this phase distribution and the phase distribution table stored in the phase distribution table storage unit 106 to obtain an estimated value of the channel quality. Calculate.

  On the other hand, as in the channel quality measurement apparatus according to the second embodiment, the amplitude region determination unit 108 and the second counting unit 103b perform determination of the amplitude region for all received signals received by the detection unit 101. In addition, the amplitude distribution is obtained by counting for each amplitude region, and the second likelihood calculation unit 107b uses this amplitude distribution and the amplitude distribution table stored in the amplitude distribution table storage unit 109 to obtain line quality. The estimated value of is calculated.

  Thus, the estimated values calculated by the first likelihood calculating unit 107 a and the second likelihood calculating unit 107 b are input to the estimated value selecting unit 110. The estimated value selection unit 110 inputs the estimated values, and the phase distribution likelihood and the second likelihood calculation obtained by the counting unit 103a for the phase distribution model calculated by the first likelihood calculation unit 107a. The likelihood of the amplitude distribution obtained in the counting unit 103b for the amplitude distribution model calculated in the unit 107b is input, and the likelihoods are compared. Subsequently, the estimated value selection unit 110 selects an estimated value calculated corresponding to the large likelihood in the above-described likelihood comparison, and outputs this as an estimated value of the channel quality.

  As described above, according to the line quality measuring apparatus according to the fourth embodiment, a system for calculating an estimated value of the line quality based on the phase region determination as in the conventional line quality measuring apparatus, and the second embodiment And a system for calculating an estimated value of the channel quality based on the amplitude region determination as in the channel quality measuring apparatus according to the above, and selecting one of these estimated values to estimate the final channel quality Since the estimated value selection unit 110 that outputs as a value is provided, the estimated value of the bit error rate or the signal-to-noise power ratio due to the phase information shift and the received signal strength change is more likely than either one. By performing the estimation, it is possible to measure the line quality with higher accuracy.

  The weighted average value calculation unit 105 and the weighted average value storage unit 104 described in the first embodiment are provided between the counting unit 103a and the likelihood calculating unit 107a and between the counting unit 103b and the likelihood calculating unit 107b, respectively. And the likelihood calculation unit 107a and the likelihood calculation unit 107b obtain the phase distribution and the amplitude distribution using the count values after weighted averaging, thereby obtaining the same effect as in the first embodiment. You can also

Embodiment 5 FIG.
Next, a line quality measuring apparatus according to the fifth embodiment will be described. FIG. 9 is a block diagram of a schematic configuration of the line quality measuring apparatus according to the fifth embodiment. In addition, the same code | symbol is attached | subjected to the part which is common in FIG. 8, and the description is abbreviate | omitted. In the line quality measuring apparatus according to the fifth embodiment shown in FIG. 9, in the line quality measuring apparatus according to the fourth embodiment, further, in the first likelihood calculating section 107a and the second likelihood calculating section 107b. A transmission path information storage unit 113 that stores information on the transmission path model corresponding to the identified phase distribution model and amplitude distribution model is provided.

  Then, when the estimated value selection unit 110 selects one of the estimated value calculated by the phase region determination or the estimated value calculated by the amplitude region determination, the transmission path information storage unit 113 The likelihood of the transmission path model corresponding to the estimated value selected by the likelihood comparison described in the fourth embodiment is determined with reference to the past transmission path information stored in the above.

  For example, when the transmission line model of the first likelihood calculation unit 107a stored in the transmission line information storage unit 113 indicates the same transmission line model in the past, the first likelihood of this time When the transmission path model specified in the calculation unit 107a is different from the transmission path model, similarly, the transmission path model of the second likelihood calculation unit 107b stored in the transmission path information storage unit 113 is the same continuously in the past. The transmission line model is shown, and it is determined whether or not a transmission line model different from that is specified in the second likelihood calculation unit 107b of this time.

  Here, when the change of the transmission path model specified in the first likelihood calculation unit 107a and the second likelihood calculation unit 107b is the same or when both are different, the normal likelihood comparison is performed. Output the selected estimate. On the other hand, if the change in one of the specified transmission path models is not the same in the first likelihood calculation unit 107a and the second likelihood calculation unit 107b, it indicates that it shows a high likelihood. Also outputs an estimated value with the same change in the transmission path model.

  In the above description, the configuration in which the transmission path information storage unit 113 is further provided for the channel quality measuring apparatus according to the fourth embodiment has been described. However, the channel quality measurement according to the first to third embodiments is described. The apparatus further includes a transmission path information storage unit 113, and when each likelihood calculation unit 107 outputs an estimated value, as described above, the likelihood of the transmission path model corresponding to the identified estimated value. Can also be determined. For example, if the transmission path information and the identified maximum likelihood phase, amplitude, or phase amplitude model transmission path are different, select the maximum likelihood among the transmission path phase, amplitude, or phase amplitude model, The channel quality corresponding to this is used as an estimated value.

  As described above, the channel quality measurement apparatus according to the fifth embodiment includes the transmission path information storage unit 113 that stores information on past transmission models specified by the likelihood calculation unit. When the value is output, the likelihood of the estimated value calculated this time can be determined by referring to the past transmission path information, and the channel quality can be estimated with higher accuracy.

  In the above first to fifth embodiments, the modulation method is QPSK modulation. However, when another modulation method is used, a communication method other than TDMA is used, or the phase region division method is changed. Even in this case, the present invention is effective.

  As described above, according to the present invention, the phase region determination unit determines which phase region the output signal point output by the detection unit is in, and the output signal point in which the counting unit is in the phase region. For each phase region and every predetermined period, and the weighted average value calculating means newly uses the weighted average value stored in the weighted average value storage means and the counting result of the counting means to newly calculate the weighted average value. And the likelihood calculation means calculates the likelihood of the weighted averaged phase distribution for the phase distribution model for each phase distribution model using the phase distribution table stored in the phase distribution table storage means. Since the maximum likelihood phase distribution model is identified and the channel quality value corresponding to the identified phase distribution model is output as the channel quality estimation value of the transmission path, even if the channel quality measurement period is short Measurement results of past signal points can be cumulatively included by weighted averaging of signal point count values, enabling high-accuracy measurement of line quality and transmission such as discontinuous data transmission and reception in burst units. When the path fluctuates with time, even if the burst size is small, it is possible to easily measure the line quality with high accuracy for each burst.

  According to the next invention, the amplitude region determining means determines which amplitude region the output signal point output by the detecting means is in, and the counting means determines the number of output signal points in the amplitude region for each amplitude. The likelihood calculation means counts the likelihood of the amplitude distribution of the received signal, which is the calculation result of the counting means, using the amplitude distribution table stored in the amplitude distribution table storage means. The maximum likelihood amplitude distribution model is identified by calculation for each amplitude distribution model, and the channel quality value corresponding to the identified amplitude distribution model is output as an estimate of the channel quality of the transmission path, so it is transmitted as a continuous wave When receiving a received signal or when receiving discontinuous data in units of bursts, the channel quality of the transmission path can be estimated by measuring the amplitude of the received signal.

  According to the next invention, the amplitude region determining means determines which amplitude region the output signal point output by the detecting means is in, and the counting means determines the number of output signal points in the amplitude region for each amplitude. Counting for each region and every predetermined period, the weighted average value calculating means newly calculates the weighted average value using the weighted average value stored in the weighted average value storage means and the counting result of the counting means, The likelihood calculating means calculates the likelihood of the weighted averaged amplitude distribution, which is the calculation result of the weighted average value calculating means, for each amplitude distribution model using the amplitude distribution table stored in the amplitude distribution table storage means. Thus, the maximum likelihood amplitude distribution model is identified, and the channel quality value corresponding to the identified amplitude distribution model is output as the estimated channel quality value of the transmission path. Well, signal point The measurement value of the past signal points can be cumulatively included by the weighted average of the count value, and the channel quality of the transmission path can be estimated by measuring the amplitude of the received signal. There is an effect that becomes possible.

  According to the next invention, the phase amplitude region determining means determines in which phase amplitude region the output signal point output by the detecting means is, and the counting means is the number of output signal points in the phase amplitude region. For each phase amplitude region and every predetermined period, and the likelihood calculating means uses the phase amplitude distribution table stored in the phase amplitude distribution table storing means to calculate the phase of the received signal as the calculation result of the counting means. The maximum likelihood phase amplitude distribution model is identified by calculating the distribution likelihood for each phase amplitude distribution model, and the channel quality value corresponding to the identified phase amplitude distribution model is estimated as the channel quality estimate of the transmission path. Therefore, when receiving a signal transmitted as a continuous wave or when receiving discontinuous data in units of bursts, both the phase information shift and the intensity change of the received signal are used. Can be estimated quality, there is an effect that it is possible to estimate more accurately the line quality of the transmission path.

  According to the next invention, the phase amplitude region determining means determines in which phase amplitude region the output signal point output by the detecting means is, and the counting means is the number of output signal points in the phase amplitude region. For each phase amplitude region and every predetermined period, and the weighted average value calculation means newly calculates a weighted average value using the weighted average value stored in the weighted average value storage means and the counting result of the counting means. In addition to calculating, the likelihood calculating means uses the phase amplitude distribution table stored in the phase amplitude distribution table storing means to calculate the weighted averaged phase amplitude distribution likelihood as the calculation result of the weighted average value calculating means. The maximum likelihood phase amplitude distribution model is identified by calculating for each phase amplitude distribution model, and the channel quality value corresponding to the identified phase amplitude distribution model is output as an estimate of the channel quality of the transmission line. Goods Even when the measurement period is short, it is possible to cumulatively include past signal point measurement results by weighted averaging of signal point count values, as well as both phase information shifts and received signal intensity changes. Can be used to estimate the channel quality of the transmission path, and it is possible to measure the channel quality with high accuracy.

According to the next invention, the transmission path information storage means stores information on the transmission path model type corresponding to the phase distribution model, amplitude distribution model or phase amplitude distribution model specified by the likelihood calculation means, and the likelihood. Since the calculation means selects the estimated value of the line quality based on the information of the past transmission path model type stored in the transmission path information storage means, the transmission path specified in the past when the estimated value is output. By referring to the information, it is possible to determine the likelihood of the estimated value calculated this time, and it is possible to estimate the channel quality with higher accuracy.
According to the next invention, the phase region determination means determines in which phase region the output signal point output by the detection means is, and the first counting means counts the number of output signal points in that phase region. For each phase region and every predetermined period, and the first likelihood calculating means receives the result of calculation of the first counting means using the phase distribution table stored in the phase distribution table storing means. The maximum likelihood phase distribution model is identified by calculating the likelihood of the phase distribution of the signal for each phase distribution model, and the channel quality value corresponding to the identified phase distribution model is estimated for the channel quality of the transmission path. On the other hand, the amplitude region determination means determines which amplitude region the output signal point output by the detection means is in, and the second counting means determines the number of output signal points in the amplitude region. Every amplitude region and every predetermined period The second likelihood calculating means uses the amplitude distribution table stored in the amplitude distribution table storage means to calculate the likelihood of the amplitude distribution of the received signal as the calculation result of the second counting means for each amplitude distribution. The maximum likelihood amplitude distribution model is identified by calculation for each model, and the channel quality value corresponding to the identified amplitude distribution model is output as the channel quality estimation value of the transmission path. Either of the first likelihood calculating means and the second likelihood calculating means is performed by comparing the maximum likelihood likelihoods calculated by the first likelihood calculating means and the second likelihood calculating means, respectively. Since the estimated value calculated on the one hand is output as an estimated value indicating the channel quality of the transmission path, it is possible to estimate the channel quality of the transmission path more likely from both the phase information shift and the received signal strength change. Can be more refined An effect that it is possible to perform high channel quality measurement.

  According to the next invention, the phase region determination means determines in which phase region the output signal point output by the detection means is, and the first counting means counts the number of output signal points in that phase region. For each phase region and every predetermined period, and the first weighted average value calculating means stores the weighted average value stored in the first weighted average value storing means and the counting result of the first counting means. A new weighted average value is calculated using the first likelihood calculating means using the phase distribution table stored in the phase distribution table storing means and the weighting that is the calculation result of the first weighted average value calculating means. The maximum likelihood phase distribution model is identified by calculating the likelihood of the averaged phase distribution for each phase distribution model, and the value of the line quality corresponding to the identified phase distribution model is determined as the channel quality of the transmission path. While output as an estimated value, amplitude region The determining means determines in which amplitude region the output signal point output by the detecting means is, and the second counting means determines the number of output signal points in the amplitude region for each amplitude region for a predetermined period. Counting every time, the second weighted average value calculating means calculates a new weighted average value using the weighted average value stored in the second weighted average value storage means and the counting result of the counting means, The second likelihood calculation means uses the amplitude distribution table stored in the amplitude distribution table storage means to calculate the likelihood of the weighted averaged amplitude distribution as the calculation result of the second weighted average value calculation means for each amplitude. The maximum likelihood amplitude distribution model is identified by calculating for each distribution model, and the channel quality value corresponding to the identified amplitude distribution model is output as the channel quality estimation value of the transmission path. These first likelihood calculating means and first The estimated values calculated in either the first likelihood calculating means or the second likelihood calculating means are transmitted by comparing the likelihoods calculated in the likelihood calculating means of Since it is output as an estimated value indicating the channel quality of the road, even if the measurement period of the channel quality is short, the measurement results of past signal points should be included cumulatively by the weighted average of the signal point count values. It is possible to estimate the channel quality of a more likely transmission path from both the phase information shift and the received signal strength change, and to measure the channel quality with higher accuracy. .

  According to the next invention, the transmission path information storage means stores information on the transmission path model type corresponding to the phase distribution model and the amplitude distribution model specified by the likelihood calculation means, respectively, and the estimated value selection means Since the estimated value of the channel quality is selected based on the information of the past transmission path model type stored in the transmission path information storage means, the transmission path information specified in the past is referred to when the estimated value is output. Therefore, it is possible to determine whether the selection result is correct together with the likelihood of the estimated value selected this time, and to determine which estimated value is output, and to estimate the channel quality with higher accuracy. There is an effect that can be.

  According to the next invention, it is possible to use a bit error rate indicating a rate of occurrence of bit errors in the received signal as an estimated value indicating the channel quality of the transmission path.

  According to the next invention, the signal-to-noise power ratio indicating the ratio of the noise power to the signal power of 1-bit information of the received signal can be used as the estimated value indicating the channel quality of the transmission path.

  As described above, the channel quality measurement apparatus according to the present invention is suitable for measuring the channel quality of a receiver used in a digital radio communication system such as satellite communication, mobile communication, and mobile satellite communication.

FIG. 1 is a block diagram of a schematic configuration of the line quality measuring apparatus according to the first embodiment. Figure 2 is an explanatory diagram showing a channel quality measuring burst of burst size T _b in the measurement time period T _p. FIG. 3 is a graph for explaining the matching of the signal-to-noise power ratio (Eb / No) output as an estimated value with the actual Eb / No. FIG. 4 is a block diagram of a schematic configuration of the line quality measuring apparatus according to the second embodiment. FIG. 5 is a signal space diagram showing a determination region of the amplitude distribution when the QPSK modulation signal is modulated in the detection unit. FIG. 6 is a block diagram of a schematic configuration of the line quality measuring apparatus according to the third embodiment. FIG. 7 is a signal space diagram showing a phase amplitude distribution determination region when a QPSK modulation signal is modulated in the detector. FIG. 8 is a block diagram of a schematic configuration of the line quality measuring apparatus according to the fourth embodiment. FIG. 9 is a block diagram of a schematic configuration of the line quality measuring apparatus according to the fifth embodiment. FIG. 10 is a block diagram showing a conventional line quality measuring apparatus. FIG. 11 is a signal space diagram showing the phase distribution determination region and an explanatory diagram showing the phase distribution.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Detection part 102 Phase area | region determination part 103 Count part 103-1, 103-2, 103-M area | region count part 103a 1st count part 103b 2nd count part 104 Weighted average value calculating part 105 Weighted average value memory | storage part 106 Phase distribution table storage unit 107 Likelihood calculation unit 107a First likelihood calculation unit 107b Second likelihood calculation unit 108 Amplitude region determination unit 109 Amplitude distribution table storage unit 110 Estimated value selection unit 111 Phase amplitude region determination unit 112 Phase Amplitude distribution table storage unit 113 Transmission path information storage unit

Claims (6)

Detection means for detecting and demodulating the received signal;
An amplitude region determination unit that determines which amplitude region the output signal point output by the detection unit corresponds to among a plurality of different predetermined amplitude regions;
Counting means for counting the number of the output signal points corresponding to the amplitude area in the amplitude area determining means for each amplitude area;
Amplitude distribution table storage means for storing a table showing the relationship between the amplitude distribution probability of each amplitude region obtained by actual measurement, simulation, theoretical calculation, etc. and a value representing the line quality for each of a plurality of different amplitude distribution models,
Using the amplitude distribution table stored in the amplitude distribution table storage means, the likelihood of the amplitude distribution of the received signal indicated by the count value for each amplitude region counted by the counting means is calculated for each amplitude distribution model. A likelihood calculating means for identifying the maximum likelihood amplitude distribution model and outputting the channel quality corresponding to the identified amplitude distribution model as an estimated value representing the channel quality of the transmission path of the received signal;
A line quality measuring apparatus comprising: And further comprising transmission path information storage means for storing information on the phase distribution model, the amplitude distribution model or the transmission path model type corresponding to the phase amplitude distribution model specified in the likelihood calculation means,
The likelihood calculating means selects an amplitude distribution model having a high likelihood based on the information of the transmission path model type stored in the transmission path information storage means, and uses the value of the line quality corresponding thereto as an estimated value. The line quality measuring apparatus according to claim 1, wherein: Detection means for detecting and demodulating the received signal;
A phase amplitude region determination unit that determines which phase amplitude region the output signal point output by the detection unit corresponds to among a plurality of different phase amplitude regions set in advance on a phase amplitude plane;
Counting means for counting the number of the output signal points corresponding to the phase amplitude area in the phase amplitude area determination means for each phase amplitude area;
Phase amplitude distribution table storage means for storing a table showing the relationship between the phase amplitude distribution probability of each phase amplitude region obtained by actual measurement, simulation, theoretical calculation, etc. and the value representing the line quality for each of a plurality of different phase amplitude distribution models When,
Using the phase amplitude distribution table stored in the phase amplitude distribution table storage means, the likelihood of the phase amplitude distribution of the received signal indicated by the count value for each phase amplitude area counted in the counting means is a phase amplitude distribution model. The likelihood of specifying the maximum likelihood phase amplitude distribution model by calculating each time, and outputting the channel quality corresponding to the specified phase amplitude distribution model as an estimated value representing the channel quality of the transmission path of the received signal Computing means;
A line quality measuring apparatus comprising: And further comprising transmission path information storage means for storing information on the phase distribution model, the amplitude distribution model or the transmission path model type corresponding to the phase amplitude distribution model specified in the likelihood calculation means,
The likelihood calculating means selects a phase amplitude distribution model having a high likelihood based on the information of the transmission path model type stored in the transmission path information storage means, and uses the value of the line quality corresponding thereto as an estimated value. 4. The line quality measuring apparatus according to claim 3, wherein Detection means for detecting and demodulating the received signal;
A phase region determination unit that determines which phase region the output signal point output by the detection unit corresponds to among a plurality of different phase regions set in advance;
First counting means for counting the number of the output signal points corresponding to the phase area in the phase area determination means for each phase area and every predetermined period;
Phase distribution table storage means for storing a table showing the relationship between the phase distribution probability of each phase region obtained by actual measurement, simulation, theoretical calculation, etc. and a value representing the line quality for each of a plurality of different phase distribution models,
Using the phase distribution table stored in the phase distribution table storage means, the likelihood of the phase distribution of the received signal indicated by the count value for each phase region counted by the first counting means is determined for each phase distribution model. A first likelihood calculation that specifies the maximum likelihood phase distribution model by calculation and outputs the channel quality corresponding to the specified phase distribution model as an estimated value indicating the channel quality of the transmission path of the received signal. Means,
An amplitude region determination unit that determines which amplitude region the output signal point output by the detection unit corresponds to among a plurality of different predetermined amplitude regions;
Second counting means for counting the number of output signal points corresponding to the amplitude area in the amplitude area determination means for each amplitude area;
Amplitude distribution table storage means for storing a table showing the relationship between the amplitude distribution probability of each amplitude region obtained by actual measurement, simulation, theoretical calculation, etc. and a value representing the line quality for each of a plurality of different amplitude distribution models,
Using the amplitude distribution table stored in the amplitude distribution table storage means, the likelihood of the amplitude distribution of the received signal indicated by the count value for each amplitude area counted by the second counting means is determined for each amplitude distribution model. A second likelihood calculation that specifies the maximum likelihood amplitude distribution model by calculation and outputs the channel quality corresponding to the specified amplitude distribution model as an estimated value indicating the channel quality of the transmission path of the received signal. Means,
By comparing the likelihood of the maximum likelihood phase distribution model calculated by the first likelihood calculating means with the likelihood of the maximum likelihood amplitude distribution model calculated by the second likelihood calculating means, Estimated value selecting means for outputting the estimated value calculated by either one of the first likelihood calculating means or the second likelihood calculating means as an estimated value indicating the channel quality of the transmission path of the received signal. When,
A line quality measuring apparatus comprising: Furthermore, transmission path information storage means is provided for storing information on transmission path model types corresponding to the phase distribution model and the amplitude distribution model specified by the first likelihood calculation means and the second likelihood calculation means, respectively. ,
The estimated value selecting means is operated in one of the first likelihood calculating means and the second likelihood calculating means based on the information of the transmission path model type stored in the transmission path information storage means. 6. The channel quality measuring apparatus according to claim 5, wherein the estimated value is output as an estimated value indicating a channel quality of a transmission path of the received signal.

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