JP6355221B2 - Wireless communication system and receiving apparatus - Google Patents

Description

  The present invention relates to a wireless transmission system and a receiving apparatus.

In digital transmission, since communication disconnection occurs when transmission quality deteriorates, it is desirable to avoid deterioration of transmission quality. The bit error rate is an index of transmission quality, and the bit error rate required for each system is different. For example, in a wireless relay transmission device that digitally transmits television broadcast program material called FPU (Field Pickup Unit), if the bit error rate after inner code decoding is 1 × 10 ⁻⁴ or less, It is possible to correct errors up to error-free (for example, see Non-Patent Document 1).
In mobile transmission using this FPU system, the bit error rate fluctuates every moment according to the state of the transmission path. Therefore, it is necessary to grasp how much transmission margin there is for the required bit error rate in order to perform stable transmission.

  Conventionally, as a method of calculating a transmission margin, received power measured at the receiving side, received CNR (Carrier to Noise power Ratio), MER (Modulation Error Ratio), etc., computer simulation, The margin is calculated from the previous verification result obtained by actual measurement or the like.

  Since the received power and the received CNR that satisfy the required bit error rate change according to the transmission path characteristics and the influence of interference, a table storing the margin for each transmission path is prepared in advance, and the margin is set according to the transmission path. Is desirable but not realistic. Therefore, it is common to set a transmission margin based on a simulation result by a computer simulation with a predetermined transmission path model or an actual measurement value of the transmission path.

In addition, AMC (Adaptive Modulation Coding) is a wireless technology that optimizes the transmission rate of a wireless device by adaptively controlling the modulation method and coding method according to the quality of the transmission path. It is known and used in HSDPA (High Speed Downlink Packet Access) and LTE (Long Term Evolution).
AMC generally selects MCS (Modulation and Coding Set) that maximizes the transmission rate while satisfying the required bit error rate of the system, based on transmission path information obtained by the receiving apparatus. For determining whether or not the required bit error rate of the system is satisfied, the reception CNR or the like is used as an index of the quality of the transmission path. The reception CNR threshold value for selecting the optimum MCS is set based on the bit error rate characteristics in each MCS obtained in advance based on computer simulation, actual measurement values, and the like.

  As a prior art document, for example, Patent Document 1 discloses an invention in which a symbol likelihood is calculated in consideration of a noise power estimation value and an interference power estimation value, and a transmission symbol is demodulated more accurately.

JP 2010-183177 A

ARIB STD-B57 2.0, “1.2 GHz / 2.3 GHz band portable OFDM digital wireless transmission system for transmitting TV broadcast program material”, The Japan Radio Industry Association Error control considering terrestrial transmission line characteristics, Annual Conference of the Institute of Image Information and Television Engineers (1998) Blanka Vucetic, "Space-Time Coding" by Jinhong Yua, Wiley

For example, in a multiple input multiple output (MIMO) transmission system in which both a transmission device and a reception device transmit using multiple antennas, transmission quality may deteriorate in an environment where the antenna correlation is high, because it becomes difficult to separate and detect received signals. Are known. Therefore, when the transmission margin is set based on the reception power, reception CNR, etc., which are the indicators of the conventional transmission path quality, the bit error rate is high in the above high antenna correlation environment even though there is a transmission margin with a high reception CNR. There arises a problem of deterioration.
In addition, when a reception CNR before erasure correction processing is used in a transmission line in which narrowband interference signals such as amateur radio are mixed, it is erroneously recognized that the reception CNR is sufficient, and an erroneous transmission margin is set. It leads to.
In the above-mentioned environment, for example, a wireless device that transmits the received CNR obtained by the receiving device as feedback information to the transmitting device and controls AMC based on the received CNR, misrecognizes the optimal MCS. Problem arises.

Generally, likelihood information in units of bits is calculated by the demodulator of the receiving apparatus, and error correction decoding processing is performed from the bit likelihood information. However, for example, in a radio system having a transmission device that performs error correction coding processing in symbol units such as 16QAM (Quadrature Amplitude Modulation), it is necessary to perform decoding processing in symbol units in the reception device. There is a problem that information cannot be obtained. For example, as a method of performing error correction coding on a symbol basis, space time trellis coding (STTC) or the like can be mentioned.
An object of the present invention is to select an appropriate modulation scheme and coding rate even in a radio system having a transmission device that performs error correction coding processing in symbol units in a high antenna correlation environment or an environment in which narrowband interference signals are mixed. To improve the transmission rate.

  The wireless communication system of the present invention is a wireless communication system having a transmission device and a reception device, the transmission device including a plurality of encoding units, a modulation unit, an RF unit, and a transmission antenna, and the reception device includes a plurality of reception antennas. An RF unit, a demodulation unit, a decoding unit, a mutual information amount calculation unit, and a margin calculation unit are provided. The demodulation unit calculates the Euclidean square distance of each replica candidate point for the transmission signal from the received signal, and the mutual information amount calculation unit is a replica. The average mutual information is calculated for the Euclidean square distance to the candidate point, and the margin calculation unit calculates the transmission margin from the demodulator output mutual information or the decoding unit input mutual information that satisfies the average mutual information and the required bit error rate. It is characterized by doing.

  The receiving apparatus of the present invention is a receiving apparatus including a plurality of receiving antennas, an RF unit, a demodulating unit, a decoding unit, a mutual information amount calculating unit, and a margin calculating unit, wherein the demodulating unit applies a received signal to a transmitted signal. The Euclidean square distance of each replica candidate point is calculated, the mutual information calculation unit calculates the average mutual information amount with respect to the Euclidean square distance with respect to the replica candidate point, and the margin calculation unit calculates the average mutual information amount and the required bit error rate. The transmission margin is calculated from the demodulating unit output mutual information amount or the decoding unit input mutual information amount which is satisfied.

  Furthermore, the receiving apparatus of the present invention is the above-described receiving apparatus, and includes an interference detection unit and an erasure correction unit arranged at least one of the preceding stage and the subsequent stage of the demodulation unit, and the interference detection unit is arranged at the preceding stage of the demodulation unit If detected, the interference component is detected from the received signal. If the interference component is placed downstream of the demodulation unit, the interference component for the Euclidean square distance output from the demodulation unit is detected. The erasure correction unit is placed before the demodulation unit. In this case, the received signal input to the demodulation unit is subjected to erasure correction processing on the received signal based on the interference detection result obtained by the interference detection unit, and the erasure correction processing unit is arranged at the subsequent stage of the demodulation unit. In this case, the Euclidean square distance output from the demodulator performs erasure correction processing to the Euclidean square distance based on the interference detection result obtained by the interference detector, and the mutual information amount calculator The average mutual information amount is calculated with respect to the Euclidean square distance after the erasure correction processing of the positive processing unit, and the margin calculating unit satisfies the average mutual information amount obtained by the average mutual information calculating unit and the required bit error rate. It is preferable to calculate the transmission margin from the output mutual information amount or the decoding unit input mutual information amount.

  According to the present invention, an appropriate modulation scheme and coding rate can be selected even in a wireless communication system having a transmission device that performs error correction coding processing in symbol units in a high antenna correlation environment or an environment in which narrowband interference signals are mixed. Thus, the transmission rate can be improved.

It is a 1st block diagram which shows an example of the transmission apparatus structure in the radio | wireless communications system which concerns on one Embodiment of this invention. It is a 1st block diagram which shows an example of a receiver structure in the radio | wireless communications system which concerns on one Embodiment of this invention. It is a 2nd block diagram which shows an example of the receiver structure in the radio | wireless communications system which concerns on one Embodiment of this invention. It is a 2nd block diagram which shows an example of the transmitting apparatus structure in the radio | wireless communications system which concerns on one Embodiment of this invention. It is a 3rd block diagram which shows an example of the receiver structure in the radio | wireless communications system which concerns on one Embodiment of this invention. FIG. 3 is a diagram for explaining a transmission margin calculation example from a bit error rate characteristic with respect to a decoding unit input mutual information amount in the modulation scheme 16QAM in FIG. 2; FIG. 3 is a diagram for explaining a transmission margin calculation example from a bit error rate characteristic with respect to a decoding unit input mutual information amount in each modulation scheme in FIG. 2.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. (First Embodiment) A first embodiment is an FPU (hereinafter referred to as MIMO-FPU) of a MIMO-OFDM (Orthogonal Frequency Division Multiplexing) system digital transmission system defined by the standard number STD-B57. And a MIMO transmission system having two receiving antennas in both the transmitting device and the receiving device.

The configuration of the wireless communication system according to the first embodiment will be described with reference to FIGS. 1 and 2. FIG. 1 is a first block diagram illustrating an example of a configuration of a transmission device in a wireless communication system according to an embodiment of the present invention.
Since the MIMO-FPU transmission apparatus uses STTC as an error correction code, two STTC encoders 100-1 and 100-2, two modulators 101-1 and 101-2, and two RF (Radio Frequency) units 102-1 and 102-2 and two transmitting antennas 103-1 and 103-2. In the transmission apparatus of this embodiment, the subscripts 1 and 2 indicate the transmission system 1 and the transmission system 2, respectively.

The information bit string to be transmitted is input to both STTC encoding units 100-1 and 100-2. The STTC encoding units 100-1 and 100-2 perform different STTC encoding processes on the input information bit strings for each system, and output encoded bits. The modulation units 101-1 and 101-2 The input coded bits are subjected to modulation processing to output a modulated signal, and the RF units 102-1 and 102-2 upconvert the baseband signal to the frequency band of the number of carriers, and transmit antenna 103-1. , 103-2 transmit radio signals.
In this embodiment, there are two transmission antennas, but the basic operation is the same with one or three or more antennas.

FIG. 2 is a first block diagram showing an example of the configuration of the receiving device in the wireless communication system according to the embodiment of the present invention.
The MIMO-FPU receiving apparatus includes two receiving antennas 104-1 and 104-2, two RF units 105-1 and 105-2, a demodulating unit 106, and a decoding unit 107, and further includes mutual information. An amount calculation unit 108 and a margin calculation unit 109 are provided.

The receiving antennas 104-1 and 104-2 receive the radio signal transmitted from the transmitting apparatus, and the RF units 105-1 and 105-2 receive the carrier frequency bands received by the receiving antennas 104-1 and 104-2, respectively. The signal is down-converted to a baseband signal, and the received signal is output to demodulator 106. In this embodiment, the subscripts 1 and 2 indicate the receiving system 1 and the receiving system 2, respectively.
In this embodiment, the number of receiving antennas is two, but the basic operation is the same with one or more than three.

The demodulator 106 performs demodulation processing using the obtained received signal vector r = [r ₁ r ₂ ... R _N ] ^T and the estimation result H ^ of the N _r × N _t channel matrix H. [] ^T indicates transposition. Calculating a Euclidean square distance _{Lj = || r-H ^ s} j || 2 between the received signal vector r and the replica (ideal reception point is calculated from the channel estimation results) candidate point H ^ _{s j.} Here, s = [s ₁ s ₂ ... S _Nt ] ^T represents a transmission signal vector, and the subscript j represents an index of a replica candidate point. The number J of replica candidates is given by J = M ^Nt where M is the number of modulation multi-values and Nt is the number of transmission antennas. Thus, this example because it is Nt = 2, the J = ^{M 2.} The obtained Euclidean square distance L _j is output to the decoding unit 107 and the mutual information amount calculation unit 108.

The decoding unit 107 performs a decoding process on the input Euclidean square distance L _j using, for example, a Viterbi algorithm with the Euclidean square distance L _j as a path metric, and outputs a decoding result. The STTC decoding process is based on Non-Patent Document 3, for example.

The mutual information amount calculation unit 108 calculates the mutual information amount based on the input Euclidean square distance L _j . The present invention is characterized by providing an apparatus capable of calculating an appropriate transmission margin even in various transmission path environments by calculating a transmission margin from the mutual information amount. Hereinafter, a process of calculating the mutual information amount from L _j will be described, and a method of calculating the margin from the calculated mutual information amount will be described.

ここで、Ｈ（Ｘ）は相互情報量における事前エントロピー、Ｈ（Ｘ｜Ｙ）は事後エントロピーと呼ばれる。The mutual information amount I (X; Y) is quantitatively shown by how much information regarding the random variable X is included in the event Y by knowing the value of the event Y, and is given by Equation 1.

Here, H (X) is called prior entropy in mutual information, and H (X | Y) is called posterior entropy.

ここで、Ｐ（Ｘ＝ｓ_ｊ）は確率変数Ｘがｊ番目の送信信号ベクトル候補点ｓ_ｊとなる確率を表す。確率変数Ｘを送信装置での送信信号ベクトルｓ（ｎ）（添え字のｎは変調後のシンボル系列のインデックスを示す）とすると、送信信号ベクトルｓ（ｎ）にはｊ通りの組み合わせがあるため、Ｐ（ｓ（ｎ）＝ｓ_ｊ）の生起確率は等確率１/Ｊと仮定すると、数式２は数式３となる。

The prior entropy H (X) in the random variable X is given by Equation 2.

Here, P (X = s _j ) represents the probability that the random variable X is the j-th transmission signal vector candidate point s _j . Assuming that the random variable X is a transmission signal vector s (n) (subscript n indicates an index of a modulated symbol sequence) in the transmission apparatus, there are j combinations of the transmission signal vector s (n). , P (s (n) = s _j ) is assumed to have an equal probability 1 / J, Equation (2) becomes Equation (3).

In the STTC encoding used in the present embodiment, since the decoding process is performed in symbol units, it is necessary to calculate the likelihood in symbol units. Therefore, it is necessary to use the received signal vector r (n) as the random variable Y, and the posterior entropy H (X | Y) = H (s (n) | r (n)) is given by Equation 4.

Therefore, in order to calculate the posterior entropy H (s (n) | r (n)), it is necessary to calculate P (s (n) = s _j | r (n)). As a constraint condition at this time, the following conditions must be satisfied.

Formula 5 indicates that the sum of conditional probabilities P (s (n) = s _j | r (n)) at each replica candidate point j is “1”. From Bayes' theorem, P (s (n) = s _j | r (n)) can be transformed into the following Equation 6.

The probability P (r (n)) that the received signal vector is generated is constant without depending on the replica candidate point. Further, when information regarding the prior probability P (s (n) = s _j ) is not owned by the receiving apparatus and is equal for all replica candidate points, P (s (n) = s _j | r (n) ) Depends only on P (r (n) | s (n) = s _j ).

Assuming that the distribution of noise mixed in the received signal vector r (n) is a Gaussian distribution, the probability P (r (n) that the received signal vector is r (n) when the replica candidate point s _j is transmitted. ) | S (n) = s _j ) is given by Equation 7 below.

ここで、Ｐ（ｒ（ｎ）｜ｓ（ｎ）＝ｓ_ｊ）のｊ＝１〜Ｊの総和はＣとする。但し、Ｃは定数である。この時、以下のように数式９に変形できる。

Here, σ ² indicates the noise power in the complex plane, and it is assumed that the noise power in each receiving system is equal. When the Euclidean square distance at the replica candidate point j is set as L _j = || r (n) −H ^ s _j || ² , P (r (n) | s (n) = s _j ) is Euclidean square distance. It can be seen that it depends only on L _j . When K = (1 / (πσ ² ) ^NT ) exp (1 / σ ² ) is set, K is not dependent on the replica candidate point j and is a constant, and therefore Equation 7 can be expressed by Equation 8.

Here, the sum of J = 1 to _{J of} P (r (n) | s (n) = s _j ) is C. However, C is a constant. At this time, it can be transformed into Equation 9 as follows.

Therefore, by using the posterior probability P ′ (r (n) | s (n) = s _j ) after normalization with the constant C, Expression 10 that satisfies the constraint condition shown in Expression 5 is obtained.

The mutual information I (n) is expressed by Equation 11 from the calculated prior entropy H (s (n)) and posterior entropy H (s (n) | r (n)).

Accordingly, the mutual information amount calculation unit 108 can calculate the mutual information amount I (n) using Equation 7 from the Euclidean square distance L _j (n) at each input replica candidate point s _j . . As a method for realizing the mutual information amount I (n) calculation, for example, the mutual information amount I (n) when the Euclidean square distance L _j (n) at each replica candidate point s _j inputted by the decoding unit 108 is given. For example, an approximate calculation using the macrolin expansion that converts the base to a natural logarithm from J to e by using a conversion table or a base conversion formula for calculating the base, and making the table unnecessary. Since the mutual information amount of Expression 13 is an instantaneous value, the variation is large. Therefore, the average mutual information _IE with reduced variation is calculated by taking a sample average with respect to the number of symbol sequences N (N is a natural number), and is output to the margin calculation unit 109.

Since the mutual information input / output characteristics of the demodulation process depend on the transmission path environment such as the antenna correlation, the average mutual information _IE after the demodulation process is a value that takes into account the influence of the antenna correlation that is not considered in the reception CNR or the like. It becomes. Further, the average mutual information _IE calculated by the mutual information calculation unit 108 does not require a parameter related to antenna correlation.

Since the mutual information amount becomes the same after the deinterleaver input / output, even when the deinterleaver is connected between the demodulating unit and the decoding unit, the average mutual information _IE calculated above has a sufficient number of symbol sequences N. If so, the average mutual information _IE may be calculated using the Euclidean square distance L ′ _j (n) input to the decoding unit 107 instead of the Euclidean square distance L _j (n) output from the demodulation unit 107.

The margin calculating unit 109, based on the mutual information I _R to achieve the following desired bit error rate γ obtained by computer simulation or the like to the average mutual information I _E which is input, obtains the transmission margin I _M in the formula 13.
I _M = I _E −I _R (Formula 13)

The mutual information input / output characteristics of the decoding process are uniquely determined according to only the error correction coding method regardless of the transmission path characteristics and the received CNR. It is a well-known technique that the bit error rate with respect to the input mutual information amount of the decoding unit 106 can be calculated from this input / output characteristic, and can be drawn in a graph as shown in FIG. For example, when using the 16QAM modulation method in the transmission device, the mutual information I _R to achieve the required bit error rate γ corresponding to the modulation scheme 16QAM can be pre-computed in advance. Therefore, it stores mutual information I _R for each modulation scheme as a table, by reference to, it is also possible to calculate transmission margin I _M of different modulation schemes and the modulation scheme in the transmission. For example, as shown in FIG. 7, the transmission margin I _{M, 2} in the modulation scheme QPSK different from the transmission margin I _{M, 1} in the modulation scheme 16QAM being set in the transmission apparatus can be calculated simultaneously.

By displaying the transmission margin I _M obtained from Expression 13 on, for example, a display or the like, the user using the receiving apparatus can know the transmission margin I _M.
The above are representative of transmission margin I _M using mutual information, may provide information analogous thereto. For example, such informs a warning alarm can be given when the transmission margin I _M is close to "0".

According to the embodiment described above, the average mutual information _IE is calculated from the Euclidean square distance L _j that is the input of the decoding unit 106, and the transmission margin _IM is calculated based on the obtained average mutual information _IE. It is possible to provide an appropriate transmission margin in consideration of the influence of antenna correlation.

Example 2 Next, Example 2 will be described with reference to FIG.
FIG. 3 is a second block diagram illustrating an example of a configuration of a receiving device in the wireless communication system according to the embodiment of the present invention.
About the processing part which attached | subjected the code | symbol same as FIG. 1, since it is the same operation | movement as a 1st block diagram, description is abbreviate | omitted. The second block diagram is a configuration provided with an erasure correction unit for the interfered signal in order to suppress deterioration of the bit error rate due to mixing of interference signals from other systems. The following description will be made assuming a receiving apparatus that receives an OFDM-modulated signal as in the first embodiment, but the present invention is also applicable to single-carrier modulation.

In the two interference detection units 200-1 and 200-2, for example, using CVI (Carrier Variance Information) disclosed in Non-Patent Document 2, reception of the l-th subcarrier mixed with interference waves is performed. detecting a signal vector _{r l,} at two erasure correction unit 201-1 and 201-2, the interference power _{r l} is the larger than the predetermined threshold value performs erasure correction process. Erasure correction process and shows the disappearance process of the data is converted into "0" or "0 to approximate the value" a r _l. And it outputs a signal vector r _d after erasure correction to the demodulator 106.

When the erasure correction process is not performed, interference waves are mixed, so that the Euclidean square distance L _j with each replica candidate point due to interference changes, and the symbol likelihood of the replica candidate point that should have a low original symbol likelihood. It is misrecognized as a high degree and adversely affects the decoding result. Therefore, the symbol likelihood becomes “0” by converting the Euclidean square distance L _j to each replica candidate point into an equal distance in the subcarrier mixed with the interference wave by the erasure correction, so that the reception characteristic is improved. can do. On the other hand, the erasure correction process generates a sample in which the input Euclidean square distance L _j of the decoding unit 106 is equidistant. Therefore, the average mutual information _IE after the erasure correction process is larger than that when no interference wave is mixed. Therefore, the transmission margin I _M calculated by Equation 13 also decreases.

It is also possible to display the transmission margin calculated without performing the erasure correction process on the display and confirm the amount of deterioration of the mutual information amount due to the interfered signal.
In FIG. 3, the interference detection units 200-1 and 200-2 and the erasure correction units 201-1 and 201-2 are provided before the demodulation unit 106, but may be provided after the demodulation unit 106.
The third embodiment described above, with respect to the signal vector r _d that erasure correction of the interference signal is applied, by calculating the mutual information I _M, a large variation in the receiving level by the interfered signal Even in this case, an appropriate transmission margin can be designed.

(Example 3) Next, Example 3 is demonstrated using FIG.
FIG. 4 is a second block diagram showing an example of the configuration of the transmission apparatus in the wireless communication system according to the embodiment of the present invention.
About the processing part which attached | subjected the code | symbol same as FIG. 1, since it is the same operation | movement as a 1st block diagram, description is abbreviate | omitted. The third block diagram is a configuration in which the transmission apparatus includes an error encoding unit that performs error correction encoding different from STTC encoding. In the following, a SISO (Single Input Single Output) transmission system system composed of one transmitting antenna and one receiving antenna will be described. However, only a receiving apparatus has two or more antennas. The present invention can also be applied to a MISO (Multiple Input Single Output) transmission system in which only the transmission system and the transmission apparatus have two or more antennas, and a MIMO transmission system in which the transmission antenna and the reception antenna have two or more antennas.

  The information bit string to be transmitted is input to the error correction coding unit 300. The error correction encoding unit 300 performs, for example, turbo encoding processing on the input information bit string and outputs encoded bits, and the modulation units 101-1 and 101-2 output the encoded bits. Modulation processing is performed to output a modulated signal, and the RF units 102-1 and 102-2 up-convert the baseband signal to the frequency band of the number of carriers and transmit the radio signal from the transmission antennas 103-1 and 103-2. To do.

FIG. 5 is a third block diagram illustrating an example of a configuration of a receiving device in the wireless communication system according to the embodiment of the present invention.
The receiving apparatus includes a receiving antenna 104, an RF unit 105, a demodulating unit 106, and a decoding unit 107, and further includes a mutual information amount calculating unit 108 and a margin calculating unit 109.

The demodulator 106 demodulates the received signal obtained in the same manner as in the first embodiment, thereby calculating the Euclidean square distance L _j between the received signal and a replica (ideal reception point calculated from the transmission path estimation result) candidate point. To do. The obtained Euclidean square distance L _j is output to the decoding unit 107 and the mutual information amount calculation unit 108. The mutual information amount calculation unit 108 similarly calculates the average mutual information amount _IE and outputs it to the margin calculation unit 109. The margin calculating unit 109, based on the mutual information I _R to achieve the following desired bit error rate γ obtained by computer simulation or the like to the average mutual information I _E which is input, obtains the transmission margin I _M.

Therefore, if the replica candidate point and the Euclidean square distance L _j are obtained, the present invention can be applied without depending on the subsequent processing. For example, by feeding back the transmission margin I _M generated by the receiving device to the transmitting device, based on the feedback information, and a wireless system in which transmission apparatus performs AMC, realizing each eigenmode transmission signal from the estimation result of the channel response For example, an eigenmode transmission system that applies an eigenvector for weighting as a weight.

  A radio communication system according to an embodiment of the present invention is suitable for a radio system having a transmission apparatus that performs error correction coding processing in symbol units in a high antenna correlation environment or an environment in which a narrowband interference signal is mixed. The coding rate can be selected to improve the transmission rate.

  Although one embodiment of the present invention has been described in detail above, the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

  Even in a wireless communication system having a transmission device that performs error correction coding processing on a symbol basis, an appropriate modulation scheme and coding rate can be selected, so that the transmission rate can be improved.

  100-1, 100-2: STTC encoding unit, 101-1, 101-2: Modulation unit, 102-1, 102-2: RF unit, 103-1, 103-2: Transmitting antenna, 104-1, 104-2: receiving antenna, 105-1, 105-2: RF unit, 106: demodulating unit, 107: decoding unit, 108: mutual information calculating unit, 109: margin calculating unit, 200-1, 200-2: Interference detection unit, 201-1 and 201-2: erasure correction unit.

Claims (3)

A wireless communication system having a transmitter and a receiver,
The transmission apparatus includes a plurality of encoding units, a modulation unit, an RF unit, and a transmission antenna.
The receiving apparatus includes a plurality of receiving antennas, an RF unit, a demodulating unit, a decoding unit, a mutual information amount calculating unit, and a margin calculating unit,
The demodulation unit calculates the Euclidean square distance of each replica candidate point for the transmission signal from the reception signal,
The mutual information amount calculation unit calculates an average mutual information amount with respect to a Euclidean square distance with respect to the replica candidate point,
The wireless communication system, wherein the margin calculating unit calculates a transmission margin from a demodulating unit output mutual information amount or a decoding unit input mutual information amount satisfying an average mutual information amount and a required bit error rate. A receiving apparatus comprising a plurality of receiving antennas, an RF unit, a demodulating unit, a decoding unit, a mutual information amount calculating unit, and a margin calculating unit,
The demodulation unit calculates the Euclidean square distance of each replica candidate point for the transmission signal from the reception signal,
The mutual information amount calculation unit calculates an average mutual information amount with respect to a Euclidean square distance with respect to the replica candidate point,
The margin calculating unit calculates a transmission margin from a demodulating unit output mutual information amount or a decoding unit input mutual information amount satisfying an average mutual information amount and a required bit error rate. The receiving device according to claim 2,
Having an interference detection unit and an erasure correction unit arranged in at least one of the preceding stage or the subsequent stage of the demodulation unit;
The interference detection unit detects an interference component from a received signal when arranged at the preceding stage of the demodulation unit, and interferes with an Euclidean square distance output from the demodulation unit when arranged at the latter stage of the demodulation unit. Detect
When the erasure correction unit is arranged before the demodulation unit, the erasure correction unit applies the received signal to the reception signal based on the detection result of interference obtained by the interference detection unit with respect to the reception signal input to the demodulation unit. Perform erasure correction processing,
The erasure correction processing unit is arranged based on a detection result of interference obtained by the interference detection unit with respect to a Euclidean square distance output from the demodulation unit when arranged in the latter stage of the demodulation unit. Perform erasure correction processing to the square distance,
The mutual information amount calculation unit calculates an average mutual information amount with respect to the Euclidean square distance after the erasure correction processing of the erasure correction processing unit,
The margin calculating unit calculates a transmission margin from an average mutual information amount obtained by the average mutual information amount calculating unit and a demodulating unit output mutual information amount or a decoding unit input mutual information amount that satisfies a required bit error rate. A receiving device.

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