JP2003174390A - Diversity receiver - Google Patents

Abstract

(57) [Summary] An object of the present invention is to estimate the level of a reception signal output from each antenna and to generate a reception signal of higher quality without causing the device to be complicated. An object of the present invention is to provide a diversity receiver. A diversity receiving apparatus receives a signal modulated by a single carrier using a plurality of receiving antennas, and selects or combines the plurality of received signals. Reference signal multiplexing means for multiplexing a reference signal outside the frequency band of a received signal output from the CDMA, and estimating the level of the received signal output from each receiving antenna with reference to the signal level of the multiplexed reference signal. The problem is solved by a diversity receiver having reception signal level estimating means.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diversity receiver, and more particularly, to estimating a reception output level from each receiving antenna by referring to a pilot signal multiplexed with a receiving signal of each receiving antenna. The present invention relates to a diversity receiver.

[0002]

2. Description of the Related Art In a transmission line in which fading occurs, such as mobile communication, the received signal quality is deteriorated when the received signal level is attenuated, but a plurality of received signals having little correlation with each other are selected or combined. By applying the technology of diversity reception, it is possible to reduce the effect (it is possible to equivalently prevent a decrease in reception level).

In this diversity reception, spatial diversity, polarization diversity, frequency diversity, route diversity system, etc. are used in order to obtain independent received waves (uncorrelated). Independent outputs are called diversity branches. As a combined reception method that combines these branches to prevent the reception level from dropping, a branch that maximizes the selective combination method: CNR (carrier power to thermal noise power ratio). , Equal gain combining method: equal weighting of received signals of all branches and adding, maximum ratio combining method: weighting of received signals of each branch proportional to amplitude level and inversely proportional to noise power And maximizing the post-synthesis CNR by performing them and adding them is known.

Generally, in a diversity receiving apparatus, a receiving section having an AGC amplifier for amplifying a received signal output from each antenna to a certain level, and a signal synthesizing section for selecting or synthesizing the received signal output from each receiving section. In the signal combining unit, any of the above-described combining reception methods is applied.

[0005]

When the signal combining section of the diversity receiving apparatus applies any one of the above-mentioned combining reception methods, the signal level of the reception signal output from each antenna is related to whichever method. Information is needed. For example, when performing maximum ratio combining or equal gain combining,
It is necessary to determine the combining ratio, and in the case of performing selective combining, it is necessary to evaluate and select the signal from each receiving unit. However, in the conventional diversity receiver, the level of the received signal output from the AGC amplifier of the receiving section is always constant, so that the AGC is
There is a problem that the level of the received signal output from each antenna is not known before amplification by the amplifier, that is, at the signal combining unit side. In many conventional diversity receivers, the signal combining unit and the receiving unit are installed separately, so that the AG used for estimating the received signal is used.
In order to send the amplification degree information of the C amplifier from the receiving section to the signal combining section, it is necessary to provide a line different from the line for sending the received signal, and a complicated device is required.

The present invention has been made in view of the above points, and its object is to estimate the level of a received signal output from each antenna without complicating the device, It is an object of the present invention to provide a diversity receiving device capable of producing a received signal of higher quality.

[0007]

In order to solve the above-mentioned problems, according to the present invention, as described in claim 1, a signal modulated by a single carrier is received by using a plurality of receiving antennas. In a diversity receiver for selecting or combining a plurality of received signals received, reference signal multiplexing means for multiplexing a reference signal outside the frequency band of the received signals output from the plurality of receiving antennas, and the multiplexed reference signal And a reception signal level estimating means for estimating the level of the reception signal output from each reception antenna with reference to the signal level of.

According to such a diversity receiving apparatus, a reference signal (hereinafter referred to as a pilot signal) is multiplexed outside the band of the received signal received by each receiving antenna, and the level of the multiplexed pilot signal is referred to. Since the level change amount from the output end of each receiving antenna to the input end of the signal combining stage that performs signal combining can be detected (the amplification degree of the AGC amplifier is estimated), the received signal output from each receiving antenna based on this detection result. Level or C of received signal
/ N can be estimated. As a result, it becomes possible to combine or select the reception signals from the respective reception antennas at the optimum ratio. Further, according to the present invention, since the pilot signal for estimating the received signal level is only multiplexed outside the band of the received signal, it is possible to provide an optimal diversity receiving device without inviting complexity of the device.

The position for inserting the reference signal is, for example,
As described in claim 2, in the diversity receiver, the reference signal multiplexing means generates and multiplexes the reference signal at a predetermined level in front of an amplifier that amplifies the received signal received to a certain value. It is configured to have a signal arrangement means.

From the viewpoint of being able to estimate the amplification factor of the received signal output from the antenna, the present invention provides the diversity receiving apparatus as described in claim 3, wherein the received signal level estimating means is , Reference signal detecting means for detecting the reference signal, amplification degree estimating means for estimating the amplification degree of the reception signal amplified by the amplifier based on the detected reference signal, and a plurality of outputs from a receiving unit including the amplifier. And a level attenuation amount estimating means for estimating the attenuation amount of the signal level up to the input of the signal combining unit for selecting or combining the received signals of the above-mentioned amplification degree and the attenuation amount of the signal level. And configured to estimate the level of the received signal output from each receiving antenna based on the.

The amplification of the reference signal is, for example, according to claim 4.
As described in, in the diversity receiver, detecting the received signal before multiplexing the reference signal,
It is configured to amplify the multiplexed signal based on the detected level of the received signal.

From the same viewpoint as above, the present invention provides claim 5.
In the diversity receiver, the reference signal is multiplexed, the received signal amplified by the amplifier is extracted by the filtering means, and the multiplexed signal is amplified based on the level of the extracted received signal. Is configured as follows.

Further, from the same viewpoint as above, the present invention provides
As described in claim 6, in the diversity receiving device, only the received signal is extracted from the signal after the reference signal is multiplexed by the filtering means, and the multiplexed signal is generated based on the level of the extracted received signal. Configured to amplify.

Further, in order to solve the above-mentioned problems, according to the present invention, as described in claim 7, OF of a synchronous modulation system in which pilots are dispersedly inserted into specific carriers and transmitted.
In a diversity receiver that receives a DM (Orthogonal Frequency Division Multiplex) signal using a plurality of receiving antennas and selects or combines the received plurality of receiving signals, the frequency of the receiving signals output from the plurality of receiving antennas. Reference signal multiplexing means for multiplexing a reference signal generated outside the band, and OFDM signal level estimating means for estimating the level of the OFDM signal output from each receiving antenna with reference to the signal level of the multiplexed reference signal. And with.

Further, in order to solve the above problems,
According to a ninth aspect of the present invention, in the diversity receiver, differential modulation is used instead of synchronous modulation for data modulation of each carrier of an OFDM (Orthogonal Frequency Division Multiplexing) signal. .

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1 of the present invention) (In the case of a single carrier type diversity receiver) FIG. 1 is a diversity receiver of a transmission apparatus using a single carrier system according to an embodiment of the present invention (hereinafter, referred to as a single It is a figure which shows the structural example of a carrier system diversity receiver.

This single-carrier type diversity receiver includes a receiving antenna A100 ₁ for receiving a radio wave transmitted from a transmitting side, and an AGC amplifier (amplifying the amplification degree) for amplifying a received signal received by the receiving antenna A100 ₁ to a certain value. A plurality of branches (branch 1 to branch 1) each including a receiving unit A200 _{1 including} an amplifier that keeps the level of a variable output signal constant, and a cable 300 ₁ that transmits the received signal to the signal combining unit 400 L), and further includes a signal combining unit 400 that combines and outputs the signals output from each branch (branch 1 to branch L). As described above, the combined reception method in diversity reception includes selection, equal gain, and maximum ratio.
There are various kinds of combining methods, and each combining method has each antenna branch (branch 1 to branch L).
Information about the signal level of the received signal output from is required. In the diversity receiving apparatus of the present invention, the receiving unit A200 ₁ multiplexes a pilot signal of a constant level outside the band of the received signal output from the receiving antenna A100 ₁ , amplifies the received signal and pilot signal with an AGC amplifier, and combines the signals. Supply to the section 400. Signal synthesizer 400
Observes and evaluates the level of the received signal from the branch 1 and the level of the pilot signal to estimate the level of the received signal output from the receiving antenna of the branch 1. In the present invention, the above-described estimation of the received signal level is also performed for the next branch (branch 2 to branch L), and the signal combining unit 400 estimates the level of the received signal for each branch and then performs the combined reception. The signal combining is performed by determining the combining coefficient according to the method.

Next, the principle of estimating the received signal level according to the present invention will be described. The subscript l of the symbols shown below is l
It indicates that it is the numerical value of the second branch. In the l-th branch, the level of the received signal output from the receiving antenna is S _r (l), and its decibel value is S _r (l).
_{r_dB} (l) [dBm], the level of the multiplexed pilot signal is P _m (l), and its decibel value is P
_{m_dB} (l) [dBm], the amplification degree of the AGC amplifier is G
(L), and its decibel value is G _dB (l) [dBm], A
The output level of the GC amplifier is E, and its decibel value is E _dB.
[DBm], the loss due to cable transmission is L (l), its decibel value is L _dB (l) [dB], the level of the received signal at the input of the signal combining unit is S _c (l), and its decibel value is S _{c_dB} (l) [dBm], the level of the pilot signal at the input of the signal combining unit _P c (l), is the decibel value _{P C_dB} (l) [dBm]. S _{c_dB}
(L) and P _{c — dB} (l) can be expressed by the following equation.

[0020]

[Equation 1]

[0021]

[Equation 2] When the multiplex level P _{m — dB} (l) of the pilot signal is known, the difference between the amplification degree G _dB (l) of the AGC amplifier and the cable loss L _dB (l) is expressed by equation (3).

[0022]

[Equation 3] Substituting equation (3) into equation (1) and solving for S _r (l) yields equation (4).

[0023]

[Equation 4] That is, the level S _{c of the} received signal observed by the signal synthesizer
By using (l) and the pilot signal level P _c (l), the received signal level S
_r (l) can be determined. Next, when the amplification degree G (l) of the AGC amplifier is controlled only by the level S _r (l) of the reception signal output from the antenna, the expression (5) is established. Even when the amplification degree G (l) of the AGC amplifier is controlled by the level of the sum of the received signal and the pilot signal, the level of the multiplexed pilot signal is sufficiently higher than the level of the received signal S _r (l). If it is smaller than, then equation (5) holds.

[0024]

[Equation 5] As described above, by referring to the received signal level S _c (l) and the pilot signal level P _c (l), the received signal level S _r (l) required for combined reception in diversity reception Can be obtained. That is,
Level of the received signal S _c (l) and, to determine the synthesis coefficient necessary when selective combining, etc. gain combining, maximum ratio combining by using a level of the pilot signal P _{c (l) (=} weighting factor) Will be able to.

Next, a method of calculating a combination coefficient in these three combined reception methods will be described by taking a single carrier type diversity receiver which receives a single carrier as an example.

First, the case of selective combining will be described.

(In case of selective synthesis) CNR of each branch
(Carrier-to-noise ratio) is usually
Thermal noise of the LNA (Low Noise Amplifier) of the receiving unit is dominant, and the CNR of each branch is γ
If (l), if the NF (Noise Figure: noise figure) of the LNA in the receiver of each branch is the same, A is taken as a proportional constant,

[0028]

[Equation 6] Is established.

The selective combining is a combining method for selecting and outputting the signal having the highest CNR among the received signals from each branch. Therefore, the synthesis coefficient W of the signal from each branch
(L) is expressed by the following equation (7). The level of the output signal after synthesis is standardized to 1, and L represents the number of branches.

[0030]

[Equation 7] Here, if it is assumed that the NFs of the LNAs of the receiving units in the respective branches are the same and the relationship of Expression (6) holds, then γ
The condition that (l) is maximum can be replaced with the condition that S _r (l) is maximum, and as a result, the formula (8) is obtained.

[0031]

[Equation 8] If the pilot carrier multiplex level P _m (l) in the receiver of each branch is constant, the magnitude of S _r (l) is determined by the magnitude of S _c (l) / P _c (l).
The expression (8) can be replaced with the following expression (9).

[0032]

[Equation 9] Further, since the output of the AGC amplifier is constant, if the cable loss from the receiving unit to the signal combining unit is constant in each branch, S _c (l) has the same value in each branch. Therefore, since the magnitude of S _r (l) is determined by the magnitude of P _c (l), the above equation (9) can be further simplified and expressed as the following equation (10). Here, the signal having the smallest level of the multiplexed pilot signal is P _n (l)
Then,

[0033]

[Equation 10] As described above, in the selective combining, it is only necessary to select the signal having the smallest level of the multiplexed pilot signal from the plurality of signals input to the signal combining unit.

Next, the case of equal gain combination will be described.

(In case of equal gain combination) equal gain combination and maximum ratio
Since all the synthesis is in-phase synthesis,
When combining the signals of
It is necessary to correct and adjust to. This phase correction means
However, since many means are already known, here
, The description is omitted, and at the input of the signal synthesis unit, each block
Assuming that the signals from the launches are in phase
The description will proceed from here on. In case of equal gain combining,
Tenor output signal level S_rRatio between branches in (l)
Save the ratio and combine as is (as described above, phase difference
Will be corrected). Therefore, using the following equation (11), the signal
Once the level of the input signal of the combiner is set to the antenna output signal level,
Bell S _rConvert to (l).

[0036]

[Equation 11] Further, considering the coefficient for normalizing the signal level after synthesis to 1, the following equation (12) is obtained.

[0037]

[Equation 12] When the pilot carrier multiplex level P _m (l) in the receiving unit of each branch is constant, the above equation (12) can be simplified as the following equation (13).

[0038]

[Equation 13] That is, the received signal level S _c (l) of the signal from each branch at the input of the combiner and the pilot signal P
By observing _r (l), the weighting coefficient W (l) for the signal from each branch can be obtained, and equal gain combining can be realized. Furthermore, since the output of the AGC amplifier is constant, if the cable loss from the receiving unit to the signal combining unit is constant in each branch, S c _(l) is the same value in each branch, the value S _c Then, the above equation (13) is transformed into the following equation (14).

[0039]

[Equation 14] Next, the case of maximum ratio combination will be described.

(In the case of the maximum ratio combination) In the maximum ratio combination, the CNR of each signal is compared with the signal from each branch.
Are weighted in proportion to and are combined to maximize the CNR of the combined signal. Γ (l), which is the CNR of the signal from each branch, is represented by the above equation (6). Here, the above equation (11) is substituted into the above equation (6) to obtain the following equation (15).

[0041]

[Equation 15] On the other hand, if the coefficient that corrects the gain difference from the antenna output end of each branch to the input of the signal combining unit caused by the AGC amplifier or cable loss is D (l), then B is taken as the proportional constant in the following equation (16). expressed.

[0042]

[Equation 16] As a result, the weighting coefficient W (l) for the signal from each branch at the input of the signal combining unit when maximum ratio combining is performed is expressed by the following equation (17) with C as a proportional constant.

[0043]

[Equation 17] When the condition shown in the following equation (18) is added to normalize the signal level after combining, A × B × C is uniquely determined, and the above equation (17) is shown in the following equation (19). Can be rewritten as

[0044]

[Equation 18]

[0045]

[Formula 19] Here, when the multiplex level P _m (l) of the pilot signal in the receiving unit of each branch is constant, the above equation (19) is simplified and rewritten as the following equation (20).

[0046]

[Equation 20] Furthermore, since the output of the AGC amplifier is constant, if the cable loss from the receiving unit to the signal combining unit is constant in each branch, S c _(l) is the same value in each branch, the value S _c Then, the above equation (20) is transformed into the following equation (21).

[0047]

[Equation 21] As a result, by observing the received signal level S _c (l) and pilot signal level P _c (l) of the signal from each branch at the input of the signal combining unit, the signal from each branch in the case of maximum ratio combining is observed. Weighting factor for W (l)
It is possible to ask.

As described above, according to the present invention, the signal of each branch is obtained from the observed S _c (l) and P _c (l) in any combination method of selection, equal gain and maximum ratio. It is possible to obtain the synthesis coefficient required when synthesizing. That is, any synthesis method can be realized.

Next, a configuration example (No. 1) and operation of the receiving section provided in the single carrier diversity receiving apparatus according to the present invention will be described with reference to FIG. Since the receiving unit takes the both identical configuration of the receiving unit A200 ₁ ~ receiver L200 _L shown in FIG. 1, here, it takes the receiver A200 ₁ branch 1 will be explained as an example.

[0050] The receiving unit A200 _1, in FIG. 2,
BPF 21, RF amplifier 22 (LNA), and distributor 2
3, an adder 24, a pilot signal generator 25, a variable gain amplifier 26 (hereinafter referred to as AGC amplifier), a local oscillator 27, a multiplier 28, a BPF 29, an IF amplifier 210, and a level detector. 211 and a control voltage generator 212.

(Description of Operation in Configuration Example (No. 1) of Receiving Unit) The received signal output from the receiving antenna A100 ₁ is input to the BPF 21, and unnecessary components outside the band such as noise and interference waves are removed to obtain the desired signal. Only the components are extracted. B
The output signal of the PF 21 is amplified by the RF amplifier 22 by a constant gain. Usually, in the receiving device, the thermal noise of the first-stage amplifier that amplifies the lowest level signal influences the C / N of the signal in the receiving device. Therefore, the RF amplifier 22 has a fixed-gain low noise with a small NF. An amplifier is used. The output signal of the RF amplifier 22 is divided into two by the divider 23, and one of the divided signals is supplied to the signal to be added input terminal of the adder 24. The pilot signal generator 25 generates a constant level pilot signal,
It is supplied to the addition signal input terminal of the adder 24. The frequency of the pilot signal is outside the received signal band and is close to the received signal frequency. The adder 24 adds a pilot signal to the received signal output from the distributor and outputs it. The output signal of the adder 24 is input to the AGC amplifier 26 and amplified to a certain level. The output signal of the AGC amplifier 26 is supplied to the added signal input terminal of the multiplier 28 for frequency conversion.

On the other hand, the other of the signals divided into two by the distributor 23 is input to the level detector 211. The level detector 211 generates a voltage corresponding to the average power or the average amplitude of the input signal and outputs it as the level information of the input signal. The output signal of the level detector 211 is input to the control voltage generator 212, and based on the level information supplied from the level detector 211, the level of the signal output from the AGC amplifier 26 becomes a predetermined constant value. To be A
A gain control signal for controlling the amplification gain of the GC amplifier 26 is generated and supplied to the gain control input terminal of the AGC amplifier 26. The level of the signal input to the level detector 211,
Since the level of the signal component supplied to the signal input terminal of the AGC amplifier 26 (excluding the component of the pilot signal added by the adder) is the same, the level of the signal output by the AGC amplifier 26 is The components of the added pilot signal are excluded).

The signal output from the AGC amplifier 26 is
The pilot signal supplied to the multiplied signal input terminal of the multiplier 28, multiplied by the local signal output from the local oscillator 27, and the received signal and the multiplexed pilot signal are simultaneously frequency-converted to the IF frequency.

[0054] If the configuration of the diversity branch space diversity, for installing in a plurality of receiving antennas spatially separated, it is necessary to transmit the cable reception signals output from the receiving unit A200 ₁ until the signal combining unit 400 Generally, in consideration of the loss in the cable, the received signal in the RF band is frequency-converted into the IF band in which the loss in the cable is small.

An image component of the received signal and pilot signal in the IF band output from the multiplier 28 is removed by the BPF 29 (or LPF), and is amplified to a predetermined level by the IF amplifier 210 in consideration of the loss in the cable. After that, it is transmitted to the signal synthesizing unit 400 by the transmission cable. Configuration of the receiving unit A200 ₁ described above realizes the AGC amplification function of the feed-forward.

Next, a configuration example (No. 2) and operation of the receiving section provided in the single carrier type diversity receiving apparatus according to the present invention will be described with reference to FIG. The same numbers are given to the components having the same functions as those in FIG.

As shown in the figure, this receiving unit A200 ₁
Is a BPF 21, an RF amplifier 22 (LNA), a distributor 23, an adder 24, and a pilot signal generator 25.
, AGC amplifier 26, local oscillator 27, and multiplier 2
8, a BPF 29, an IF amplifier 210, a level detector 211, a control voltage generator 212, and a BPF 213.

(Explanation of Operation in Configuration Example ( _No. 2) of Receiving Unit) The received signal output from the receiving antenna A100 ₁ has unnecessary components outside the band such as noise and interference wave removed by the BPF 21, and only the desired wave component is present. RF after being extracted
It is amplified by the amplifier 22 by a constant gain. Adder 24
Adds (multiplexes) the output signal of the RF amplifier 22 and the pilot signal of constant amplitude and constant frequency output from the pilot signal generator 25 and outputs the result. Next, the output signal of the adder 24 is input to the signal input terminal of the AGC amplifier 26. A
The output signal of the GC amplifier 26 is divided into two by the divider 23, and one of the two divided signals is input to the BPF 213. The BPF 213 removes the pilot signal component multiplexed by the adder 24 and supplies it to the level detector 211 as the received signal component only. The BPF 213 that removes the pilot signal component is a notch filter or B
It may be an EF (band elimination filter). The level detector 211 generates a voltage corresponding to the average power or average amplitude of the input signal and supplies it to the control voltage generator 212 as level information. Control voltage generator 212
Is A based on the level information from the level detector 211.
A gain control signal for controlling the amplification gain of the GC amplifier 26 is generated and supplied to the gain control input terminal of the AGC amplifier 26, and the level of the signal output from the AGC amplifier 26 (not including the pilot signal component) becomes constant. The feedback loop is configured as follows.

On the other hand, the other of the two signals distributed by the distributor 23 is input to the multiplied signal input terminal of the multiplier 28 for frequency conversion, and is multiplied by the local signal output from the local oscillator 27. The received signal and pilot signal are I
The frequency is converted to the F band. The IF band received signal and the pilot signal output from the multiplier 28 are BPF 29 (LPF
However, the image component is removed by the IF amplifier 21
After being amplified to a predetermined level by 0, the signal is transmitted to the signal synthesizing section 400 by the transmission cable.

Next, a configuration example (No. 3) and operation of the receiving section provided in the single carrier diversity receiving apparatus according to the present invention will be described with reference to FIG. The same numbers are given to the components having the same functions as those in FIG.

As shown in the figure, this receiving unit A200 ₁
Is a BPF 21, an RF amplifier (LNA) 22, a distributor 23, an adder 24, and a pilot signal generator 25.
, AGC amplifier 26, local oscillator 27, and multiplier 2
8, a BPF 29, an IF amplifier 210, a level detector 211, a control voltage generator 212, and a BPF 213.

(Explanation of Operation in Configuration Example ( _No. 3) of Receiving Unit) The received signal output from the receiving antenna A100 ₁ has unnecessary components outside the band such as noise and interference wave removed by the BPF 21 and has only the desired wave component. RF after being extracted
It is amplified by the amplifier 22 by a constant gain. Adder 24
Outputs the output signal of the RF amplifier 22 and a pilot signal of a constant amplitude and a constant frequency output from the pilot signal generator 25, and outputs the multiplexed signal. Next, the output signal of the adder 24 is input to the distributor 23 and divided into two. One of the signals divided by the distributor 23 is supplied to the signal input terminal of the AGC amplifier 26, and the other is input to the BPF 213. BPF21
3 removes the pilot signal component multiplexed by the adder 24 to extract only the received signal component and supplies it to the level detector 211. As in the case of FIG. 3 described above, the BPF 213 aims at removing only the pilot signal component, and may be either a notch filter or a BEF (band elimination filter). The level detector 211 generates a voltage corresponding to the average power or average amplitude of the input signal and supplies it to the control voltage generator 212 as level information. The control voltage generator 212 generates a gain control signal for controlling the amplification gain of the AGC amplifier 26 based on the level information from the level detector 211, and supplies the gain control signal to the gain control input terminal of the AGC amplifier 26. The amplification gain of the AGC amplifier 26 is controlled so that the level of the signal output by the amplifier 26 (the level of only the reception signal that does not include the pilot signal component) is constant.

The output signal of the AGC amplifier 26 is input to the multiplied signal input terminal of the multiplier for frequency conversion, and is multiplied by the local signal output from the local oscillator 27 so that the received signal and the pilot signal are in the IF band. Frequency converted. An image component is removed from the IF band received signal and the pilot signal output from the multiplier 28 by the BPF 29 (or LPF), and the signal combining unit 400 is transmitted by the transmission cable.
Transmitted up to. In this configuration example, a feedforward type AGC function is realized. In any of the configuration examples of FIGS. 2 to 4 described above, the AGC amplifier 26 may be configured to vary the amplification factor of the amplification circuit itself, or may be realized by combining a high gain amplifier and a variable attenuator. May be.

Next, the signal combiner 40 provided in the single carrier type diversity receiver according to the present invention.
A configuration example (No. 1) and operation of No. 0 will be described with reference to FIG.

As shown in the figure, the signal synthesizer 400
Includes a phase adjusting unit and a level detecting unit for each branch (phase adjusting unit A411 ₁ to phase adjusting unit L411 _L ,
Level detector A412 ₁ ~L412 _L), further combining coefficient generation circuit for determining the weighting coefficient of the received signal 414
When the multiplier ₄₁₃ 1 _{~413 L} for multiplying the weighting factor determined by the received signal and the synthesis coefficient generation circuit 414 is outputted from the level detection unit A412 ₁ ~L412 _L,
And a combiner 415 for combining the output signals from the multipliers 413 _{1 to} 413 _L. Since the processing of the received signals of the branch 1 to the branch L in this signal combining unit is the same, only branch 1 will be described below.

(Explanation of Operation in Configuration Example (No. 1) of Signal Combining Section) The reception signal of the branch 1 output from the receiving antenna A100 ₁ and added with the amplification and pilot signal in the receiving section A200 ₁ is signal-combined by the cable. It is transmitted to part 400, after receiving the correction of the signal phase difference between the branches at the phase adjustment unit A411 _1, level detector A41
It is input to 2 ₁ . Phase corrected received signal input to the level detection unit A412 ₁ is 3 distributed divider 4121. The first distributed signal output from the distributor 4121 is input to the pilot signal extracting BPF 4122, and only the pilot signal component added by the receiving unit A200 ₁ is extracted by the BPF filtering. The pilot signal thus extracted is used as the level detector 4
It is input to 125 and the level is detected. The level information of the pilot signal output from the level detector 4125 is input to the synthesis coefficient generation circuit 414 as P _c (1).

The second distributed signal output from distributor 4121 is input to received signal extracting BPF 4123, and only the received signal that does not include the pilot signal is extracted. The signal output from the reception signal extracting BPF 4123 is input to the level detector 4124 to detect the level. The level information of the received signal output from the level detector 4124 is S _c (1) as the synthesis coefficient generation circuit 4
14 is input.

Third distribution output from distributor 4121
The signal is the level detection unit A412.₁Output from the multiplier 4
Thirteen₁The synthesis function output from the synthesis coefficient generation circuit 414 at
It is multiplied by a number signal and input to the combiner 415. Blanc
The received signals of branch 2 to branch L are the received signals of branch 1.
Similarly to the phase adjustment unit B411_Two~ L411_LBranch in
After the correction of the phase difference between the levels, the level detection unit B412_Two
~ L412_LIn the same way as the processing of the received signal of branch 1.
Such processing is performed. Each level detection unit A412 ₁~ L4
12_LLevel of the pilot signal of each branch detected by
Information P_c(L) and level information of received signal of each branch
S_c(L) is input to the synthesis coefficient generation circuit 414, respectively.
To be done.

The synthesis coefficient generation circuit 414 receives the input P _c
W (l) is calculated and output from (l) and S _c (l), and each of the level detection units 412 in the multipliers 413 _{1 to} 413 _L.
The received signals of the respective branches output from _{1 to} 412 _L are weighted and input to the combiner 415. Synthesizer 415
Adds and combines the input signals of the respective branches. The synthesis coefficient generation circuit 414, when performing selective synthesis,
Formula (10), formula (14) for equal gain combining, and formula (21) for maximum ratio combining are used to obtain the combining coefficient W (l).

Next, a configuration example (No. 2) and operation of the signal synthesizing section provided in the single carrier type diversity receiving apparatus according to the present invention will be described with reference to FIG. The only difference from the first configuration example shown in FIG. 5 is the internal configuration of the level detection unit. Therefore, here
Only the level detector will be described (level detector A412
₁ will be described as an example).

[0071] The level detecting unit A412 ₁ includes a phase adjusting unit A
The received signal that has been compensated for the signal phase difference between the branches by 411 ₁ is input, and the signal is divided into two by the distributor 4121. The first distributed output from the distributor 4121 is input to the pilot signal extracting BPF 4122, and the receiving unit A
200 only the pilot signal component is multiplexed with ₁ are extracted. The pilot signal thus extracted is input to the level detector 4125 to detect the level. The level information of the pilot signal detected by the level detector 4125 is output from the level detection unit 4125 and input to the synthesis coefficient generation circuit 414 as P _c (1).

On the other hand, the second distributed output from distributor 4121 is input to received signal extracting BPF 4123, and only the received signal not including the pilot signal is extracted. The reception signal extracted by the reception signal extracting BPF 4123 is further input to the distributor 4126 and divided into two. The first distribution output distributed by the distributor 4126 is input to the level detector 4124 to detect the level. The level information of the received signal output from the level detector 4124 is output from the level detector 4124 as S _c (1) and input to the synthesis coefficient generation circuit 414.

The second distribution output from distributor 4126 is
After being output from the level detecting unit 412 _1, the multiplier 413
₁ and is multiplied by the synthesis coefficient W (1) output from the synthesis coefficient generation circuit 414. Received signal after multiplication synthesis coefficient output from the multiplier 413 ₁ is input to the combiner 415, it is combined with the received signal from the other branches received similar treatment. Phase adjusting unit B411 ₂ ~ phase adjustment portion L
411 _L performs the same processing as the phase adjustment unit A411 ₁ .
Level detector L412 _L from the level detection unit B412 ₂ performs the same processing as the level detection unit A412 _1. further,
The multipliers 413 ₂ to 413 _L perform the same processing as the multiplier 413 ₁ . The synthesis coefficient generation circuit 414 performs the calculation shown in the equation (10) when performing the selective synthesis, the equation (14) when the equal gain synthesis is performed, and the equation (21) when the maximum ratio synthesis is performed. The coefficient W (l) is calculated and the multiplier 41
3 ₁ to multiplier 413 _L , respectively.

According to the above embodiment, each of the receiving units A200 _{1 to} L200 _L of each branch inserts a pilot signal outside the band of the received signal, and the signal combining unit 400 refers to the level of the pilot signal. Reception antennas A100 _{1 to} L100 _L in the branches _{1 to L}
Level from the output end of the branch to the input end of the signal synthesizing unit 400 is detected, and from each of the detection results, each of the branches 1 to L is detected.
Estimate the receiving antenna output level of. Therefore, even if the input signal level of the signal synthesizing unit 400 is not proportional to the C / N of the received signal, the signal synthesizing unit 400 synthesizes the received signals from the respective branches 1 to L at an optimal synthesizing ratio, or It becomes possible to select.

(Embodiment 2 of the present invention) (In the case of an OFDM diversity receiver) Next, the present invention is applied to an OFDM (Orthogonal Frequency Division Mu) which is a multi-carrier digital modulation system as a modulation system.
A case where the present invention is applied to a diversity receiving device of a transmission device using the ltiplex) modulation method will be described. In diversity reception of an OFDM signal, it is known that a high diversity gain can be obtained by selecting and combining for each carrier of the OFDM signal. In this case, signal synthesis is generally performed after FFT (Fast Fourier Transform) processing.

FIG. 7 shows an OF according to an embodiment of the present invention.
It is a figure which shows the structural example of the diversity receiver (henceforth an OFDM diversity receiver) which applied the DM modulation system. This OFDM diversity receiver transmits a received signal by a receiving antenna A110 ₁ that receives a radio wave transmitted from a transmitting side, a receiver A210 ₁ that includes an AGC amplifier that amplifies the received signal to a certain value, and the like. composed of the cable 310 ₁ branch 1
Is provided (branch 1 to branch L), and further,
An OFDM demodulation unit that demodulates the OFDM signals output from the branches 1 to L and a signal synthesis unit that synthesizes the demodulated OFDM signals are integrated into an OFDM demodulation / signal synthesis unit 500. Receiver A21 shown in FIG.
The configuration of 0 _{1 to L} 210 _L is the same as the configuration of the single carrier system shown in FIGS. 2 to 4 described above. Also, O
The FDM modulation method includes a differential modulation method that transmits information by the inter-symbol difference of the phase and amplitude of each carrier in the OFDM signal, and a multi-value QAM method (eg 16QA) for each carrier.
M) is used, pilot carriers with known amplitude and phase (this pilot is referred to as a scattered pilot (SP)) are arranged at regular intervals in both the frequency direction and the symbol direction, and at the time of demodulation. There are two methods, a synchronous modulation method, which is used as a standard for the.
Therefore, the OFDM diversity receiving apparatus to which the differential modulation method is applied and the signal combining unit of the OFDM diversity receiving apparatus to which the synchronous modulation method is applied have different configurations and will be described separately.

First, an OFDM signal diversity receiver to which the synchronous modulation system is applied (hereinafter referred to as the synchronous modulation system OFD).
The M signal diversity receiving device) will be described.

In the synchronous modulation type OFDM signal diversity receiver, a pilot carrier having a known phase and amplitude multiplexed in the frequency direction at regular intervals on the transmitting side is detected on the receiving side, and the detected phase value and amplitude are detected. The value estimates the frequency characteristic of the transmission line at the pilot carrier frequency. This process is normally performed by the FFT on the receiving side.
It is obtained by dividing the complex amplitude of the pilot carrier included in the carrier data on the frequency axis output from the circuit by the complex amplitude of the transmitted pilot carrier. Since the complex data representing the frequency characteristics of the transmission path obtained in this way is data in which the transmission path characteristics of each carrier of the OFDM signal are thinned out at a constant carrier interval, by performing an appropriate complementing process, the OFDM It is possible to obtain the transmission line characteristic at the frequency of each carrier of the signal. Here, H (l, m, n) is a complex number, and H
The frequency amplitude characteristic is obtained by calculating the absolute value of (l, m, n), and the frequency phase characteristic is obtained by calculating the argument. Here, 1 is a branch number, m is a carrier number, and n is a symbol number. The same applies to other symbols used in the following description.

The synchronous modulation type OFDM signal diversity receiving device is capable of performing diversity reception by three combined receiving methods as in the case of the single carrier type diversity receiving device described above. Here, first, conditions common to these three combined receptions will be described.

(Condition Common to Each Combining Method) The complex amplitude of each carrier of the OFDM signal at the output of the receiving antenna is S
_{Let r} (l, m, n) be the complex amplitude of each carrier at the input of the signal combining unit, and be S _c (l, m, n). It is necessary to correct the phase difference between the branches and perform the synthesis in any one of the synthesis methods including the selective synthesis, the equal gain synthesis, and the maximum value synthesis. To correct the phase difference between the branches of each carrier, the complex conjugate of the transmission line characteristics H (l, m, n) at the frequency of each carrier of each branch is taken, and H (l, m,
The complex amplitude of each carrier obtained by FFT of the received signal is multiplied by a complex number as shown in equation (101) obtained by normalizing with the absolute value of n), and H (l, m, n) is obtained. Should give opposite phase rotation.

[0081]

[Equation 22] Therefore, the composite coefficient W (l, m, n) is C (l, m,
n) is represented by the following equation, where n is a real number.

[0082]

[Equation 23] First, the case where the received signal is combined at the receiving antenna output or the LNA output which is not affected by the AGC amplifier and cable loss of the receiving unit and the AGC amplifier arranged in the preceding stage of the A / D converter of the OFDM demodulating unit Think The receive antenna output or LNA output signal is S _r (l, m,
n), W _r (l, m, n) is a combining coefficient when the received signals are combined in the signal combining unit, and S is an output signal of the signal combining unit.
_{If o} (m, n), the following expression (103) is established.

[0083]

[Equation 24] On the other hand, the received signal S _r (1, m, n) is the transmitted signal S _r
Since (m, n) is the result of being influenced by the transmission path characteristic H (l, m, n), the following expression (104) is established.

[0084]

[Equation 25] Substituting the above equation (104) into the above equation (103),
Expression (105) is obtained.

[0085]

[Equation 26] Then, by substituting the equation (102) into the equation (105),

[0086]

[Equation 27] Is obtained.

By applying the equalization condition of the equation (107) to the equation (106), the diversity reception output S _o (m, n) is equal to S (m, n) in the transmission signal. Expression (108) is obtained.

[0088]

[Equation 28]

[0089]

[Equation 29] From the above equation (108), C (l, m, n) is calculated (10
By substituting into the equation (2), the synthesis coefficient W _r (l, m, n) can be obtained.

Next, the AGC amplifier and cable of the receiving section
Loss, placed before the A / D converter in the OFDM demodulator
Due to the influence of the AGC amplifier,
Consider the case of combining received signals in
It Received signal from each branch at the input of the signal combiner
FFT of each signal, each branch, complex oscillation of each carrier
Width S_c(L, m, n), received signal in the signal combining unit
The synthesis coefficient at the time of synthesis is W _c(L, m, n), in the signal synthesizer
The output signal after signal synthesis is S_oIf (m, n), then
Expression (109) is established.

[0091]

[Equation 30] Further, the following equation (110) is obtained by applying the above equation (11) to each carrier of the OFDM signal.

[0092]

[Equation 31] Substituting the above equation (110) into the above equation (109),

[0093]

[Equation 32] Is obtained.

Therefore, from the above formula (111), W _r is

[0095]

[Expression 33] Becomes

By solving the above equation (112) for W _c (l, m, n), the following equation (113) is obtained.

[0097]

[Equation 34] Here, W _r (l, m, n) is usually (11
Since it is a function of the transmission line characteristic H (l, m, n) as shown in the equation (4), the above equation (113) is expressed by the following equation (11).
It can be rewritten as in equation (5).

[0098]

[Equation 35]

[0099]

[Equation 36] On the other hand, H (l, m, n) is an appropriate interpolation of the characteristics discretely obtained on the frequency axis and the time axis based on the demodulated data of the pilot carrier having a known amplitude and phase included in the OFDM signal. Since the values are obtained by performing the processing, when they are detected and generated at the input of the combining unit where the gains are different between the branches, they are affected by the gain difference between the branches. H detected and generation at the input of the signal combining unit (l, m, n) and _{H D}
If (l, m, n), then this H _D (1, m, n),

[0100]

[Equation 37] It is represented by.

Furthermore, the above equation (116) is converted into H (l, m,
Solving for n),

[0102]

[Equation 38] Is obtained.

Therefore, due to the effects of the AGC amplifier of the receiving section, the cable loss, and the AGC amplifier arranged in the preceding stage of the A / D converter of the OFDM demodulating section, the received signal is received by the signal combining section having different gains between the branches. To obtain the synthesis coefficient W _c (l, m, n) for synthesis, first, W
_{Then, r} (l, m, n) is obtained, and then converted into W _c (l, m, n) using the equation (115), and (117)
Using the formula H (l, m, n) may be converted to _{H D (l, m, n} ) to.

Next, an example of calculation of the combining coefficient in each combining receiving method applicable to the synchronous modulation type OFDM signal diversity receiving apparatus will be described.

First, an example of calculating the combination coefficient when the selective combining method is applied as the combining receiving method will be described.

(Case of Selective Combining) Selective combining is a method of selecting a signal from a branch having the highest CNR, ie, the largest amplitude, for each carrier. The amplitude of each carrier as a result of FFT of the received signal is the transmission line characteristic H.
Since it is determined by (l, m, n), the following expression (118) is established.

[0107]

[Formula 39] Then, substituting the equation (101) into the equation (108),

[0108]

[Formula 40] Is obtained.

When the above equation (119) is arranged,

[0110]

[Formula 41] Becomes Furthermore, the above expression (120) is converted into α (l, m, n)
Solving for

[0111]

[Equation 42] Is obtained.

The above (10
Expression (1), Expression (120) and Expression (118) are replaced by Expression (102).
Substituting into the equation, the synthesis coefficient W when there is no influence of the AGC amplifier of the receiving section, the cable loss, and the AGC amplifier arranged before the A / D converter of the OFDM demodulating section
_r (l, m, n) is calculated by the following equation.

[0113]

[Equation 43] Next, using equations (115) and (117), W
_r (l, m, n) is A at the input of the AGC amplifier and cable loss of the receiver and the A / D converter of the OFDM demodulator
The expression (123) shows the result of conversion into the synthesis coefficient W _c (l, m, n) in the signal synthesis unit, in which the gain difference between the branches due to the GC amplifier or the like is compensated by the insertion of the pilot signal according to the present invention. .

[0114]

[Equation 44] Next, the case of equal gain combination will be described.

(In the case of equal gain combination) The equal gain combination is a method of performing equal gain combination after compensating for the phase difference between each branch of each carrier. C (1, m,
Substituting n () with α (m, n) that does not depend on the branch and substituting it into the above equation (108) together with the above equation (101), the following equation (124) is obtained.

[0116]

[Equation 45] When the above formula (124) is arranged,

[0117]

[Equation 46] And the equation (125) is solved for α (m, n),

[0118]

[Equation 47] Is obtained.

Furthermore, the above equation (101) and the above (12)
Substituting equation (6) into equation (102) above, the AGC of the receiver
The synthesis coefficient W _r (l, m, n) when not influenced by the amplifier, the cable loss, and the AGC amplifier arranged in the preceding stage of the A / D converter of the OFDM demodulation unit is calculated as follows.

[0120]

[Equation 48] Also, using the above equations (115) and (117), W
_r (l, m, n) is A at the input of the AGC amplifier and cable loss of the receiver and the A / D converter of the OFDM demodulator
The result obtained by converting the gain difference between the branches due to the GC amplifier or the like into the synthesis coefficient W _c (l, m, n) in the case of compensating by the insertion of the pilot signal according to the present invention is as follows.
It is shown in the equation 28).

[0121]

[Equation 49] Next, the case of maximum ratio combination will be described.

(Case of Maximum Ratio Combining) Maximum ratio combining is a method of combining by weighting in proportion to the amplitude of each carrier. C (l, m, n) in the above equation (102) does not depend on the absolute value of the transmission path characteristic H (l, m, n), that is, the received branch, the absolute value of the amplitude of each carrier, and the branch. Assuming that it can be represented by the product of the value α (m, n), the following equation (129) is obtained.

[0123]

[Equation 50] The above equation (129) is combined with the above equation (101) in the above (10
Substituting into equation (8), the following equation (130) is obtained.

[0124]

[Equation 51] When the above formula (130) is arranged,

[0125]

[Equation 52] And the equation (131) is solved for α (m, n),

[0126]

[Equation 53] Is obtained.

Furthermore, the above equation (101) and the above (13)
Substituting equation (2) into equation (102) above, the AGC of the receiving unit
The synthesis coefficient W _r (l, m, n) when not affected by the amplifier, the cable loss, and the AGC amplifier arranged in the preceding stage of the A / D converter of the OFDM demodulation unit is obtained as follows.

[0128]

[Equation 54] Also, using the above equations (115) and (117), W
_r (l, m, n) is A at the input of the AGC amplifier and cable loss of the receiver and the A / D converter of the OFDM demodulator
The result obtained by converting the gain difference between the branches due to the GC amplifier or the like into the synthesis coefficient W _c (l, m, n) in the case of compensating by the insertion of the pilot signal according to the present invention is as follows.
Equation 34).

[0129]

[Equation 55] Next, a device configuration example of the diversity receiver for the synchronous modulation type OFDM signal will be described with reference to FIG. The configuration of the receiving units A210 _{1 to} L210 _L shown in FIG. 7 is the same as that of the single carrier system shown in FIGS. Therefore, here
The OFDM demodulation / signal combining unit 500 will be described.

The OFDM demodulation / signal combining section 500 is provided with OFDM demodulation sections A501 _{1 to} L501 _L for receiving the OFDM signals output from the branches _{1 to L} and performing demodulation processing for each branch. Equipped O
A signal synthesizing circuit 520 for synthesizing the signals output from the FDM demodulation units A501 _{1 to} L501 _L, and a signal synthesizing circuit 52.
Judgment / identification circuit 53 for judging the signal output from 0
It consists of 0 and. OFDM demodulator A501 _{1 to} L5
Since 01 _L has the same configuration, the OFDM demodulation unit A501 ₁ that receives the received signal from the branch 1 will be described below as an example.

As shown in the figure, the OFDM demodulation unit A50
1 _1, BPF5101, multiplier 5102, a local oscillator 5103, BPF5104, AGC amplifier 5105, A
/ D converter 5106, fixed pattern generator 5107, fixed pattern generator 5108, multiplier 5109, multiplier 5
110, LPF 5111, LPF 5112, 4: 1 decimation circuit 5113, 4: 1 decimation circuit 5114, frequency phase error detection circuit 5115, complex phase rotator 5116, effective symbol period extraction circuit 5117, FFT circuit 511.
8, pilot signal power detection circuit 5119, frame synchronization detection circuit 5120, SP extraction / transmission path characteristic estimation circuit 5
And 121.

Next, the operation of this configuration will be described.

The reception signal output from the reception antenna A110 ₁ is amplified in the reception unit A210 ₁ , and after the pilot signal is added, the frequency is converted into the first IF signal. The first IF output from the receiver A210 ₁
Signal is transmitted to OFDM demodulation and signal combining unit 500 by a cable 310 _1, each branch 1~L shown in FIG. 8
Are input to the OFDM demodulation units A501 _{1 to} L501 _L corresponding to. Since the OFDM demodulation units A501 _{1 to} L501 _L have the same configuration, the OFDM demodulation unit A here is used.
The operation will be described taking 501 ₁ as an example.

[0134] received signal in the branch 1, which is input to the OFDM demodulation unit A 501 ₁ (first IF signal), BPF 51
After removing unnecessary signal components in 01, the multiplier 5102
Is input to the multiplied signal input terminal. Next, the local signal output from the local oscillator 5103 is added to the multiplier 5102.
Input to the multiplication signal input terminal of the
Convert to signal. The center frequency of the second IF signal is A /
The sampling frequency of the D converter 5106 (four times the FFT clock frequency) is set to 1/4. After the image component is removed by the BPF 5104, the second IF signal output from the multiplier 5102 is A by the AGC amplifier 5105.
The dynamic range of the / D converter 5106 is effectively used to minimize the quantization error, and the amplitude is adjusted to an optimum level so that signal clipping does not occur and A / D conversion is performed.
It is input to the converter 5106. This A / D converter 510
The IF signal converted into a digital signal in 6 is divided into two, and a multiplier 510 is used as an I-axis signal and a Q-axis signal, respectively.
9 and 5110 are input to the multiplied signal input terminals. The I-axis signal input to the multiplier 5109 becomes a baseband signal after being multiplied by the repeated signal of {1, 0, -1, 0} output from the fixed pattern generator 5107.

In this way, the I-axis signal frequency-converted to the baseband band by the multiplier 5109 and output is the LPF5.
The image component is removed at 111, and the thinning processing is performed at the 4: 1 thinning circuit 5113 to convert the sampling frequency to 1/4.

On the other hand, the Q-axis signal input to the multiplier 5110 is output from the fixed pattern generator 5108.
It is converted into a baseband signal by being multiplied by a repeated signal of {0, -1,0,1}. An image component is removed from the Q-axis signal that has been frequency-converted into the baseband band and output, and the 4: 1 decimation circuit 5114 performs decimation processing to convert the sampling frequency to 1/4. The I-axis signal output from the 4: 1 decimation circuit 5113 and the Q-axis signal output from the 4: 1 decimation circuit 5114 are each divided into two, and the complex phase rotator 5116
Is input to the frequency / phase error detection circuit 5115. The frequency / phase error detection circuit 5115 generates and outputs a complex reproduction carrier signal for correcting the detected frequency / phase error (refers to a carrier signal in which the detected error frequency is the carrier frequency and the detected error phase is the signal phase). Then
The complex phase rotator 5116 is supplied. Complex phase rotator 5
116 is a 4: 1 decimation circuit 5113 according to the reproduced carrier signal supplied from the frequency phase error detector 5115.
I-axis signal supplied from the 4: 1 thinning circuit 5114
The frequency-phase error of the Q-axis signal supplied from the device is corrected and output, and is supplied to the effective symbol period extraction circuit 5117. The effective symbol period extraction circuit 5117 removes the guard intervals included in the supplied I-axis signal and Q-axis signal to extract only the effective symbol period, and the FFT circuit 511.
Supply to 8. The FFT circuit 5118 converts the supplied I-axis and Q-axis signals (carrier data) on the time axis into I-axis and Q-axis signals on the frequency axis and outputs them. In this way
The I axis on the frequency axis output from the FFT circuit 5118,
The Q-axis signal is divided into four, and the signal combining circuit 52
0, the frame synchronization detection circuit 5120, the pilot signal power detection circuit 5119, and the SP extraction / transmission path characteristic estimation circuit 5121. Frame synchronization detection circuit 512
The frame synchronization is performed by the I and Q axis signals on the frequency axis input to 0 (for example, the transmission signal is an IS of terrestrial digital broadcasting).
DB-T (integrated services digital broadcasting)
-terrestrial) signal, one frame consists of 204 symbols) is detected, and the number of the symbol of the SP symbol (for example, 4 sequences in ISDB-T signal) of the current symbol is detected. The information shown is generated and supplied to the SP extraction / transmission path characteristic estimation circuit 5121. The SP extraction / transmission path characteristic estimation circuit 5121 uses an FFT.
The I and Q axis signals (carrier data) on the frequency axis supplied from the circuit 5118 and the frame synchronization detection circuit 5120.
The SP data is extracted and interpolated based on the SP sequence information supplied from to generate the transmission path characteristic H (l, m, n) and is supplied to the signal synthesizing circuit 520. The pilot signal power detection circuit 5119 is used in the receiver A210 ₁ (see FIG. 7).
At, the power of the pilot signal superimposed outside the band of the signal is detected, converted into the amplitude P _c (l) of the pilot signal, and supplied to the signal combining circuit 520. Here, the receiving unit A210 ₁
The frequency of the pilot signal superimposed on
Since it is not synchronized with the clock frequency of, the FFT circuit 5
The data output from 118 is, as shown in FIG.
Appears dispersedly at multiple frequency sample points outside the band. Therefore, as shown in the following equation (135), the sum of signal powers in the vicinity of the frequency sample points of the FFT corresponding to the frequency of the pilot signal is calculated, and the square root is calculated to convert the sum into the signal level.

[0137]

[Equation 56] Here, m1 and m2 are the following (13) where mp is the carrier number of the FFT data corresponding to the frequency of the pilot signal.
Expressions 6) and (137) are used.

[0138]

[Equation 57]

[0139]

[Equation 58] Here, Δm is a positive integer and may be selected so as to add all the energies of the pilot signal according to the frequency stability of the pilot signal added by the receiving unit.

On the other hand, from the signal synthesizing circuit 520 to the receiving unit A
By supplying an FFT clock up to 210 ₁ or a reference signal frequency-synchronized with the FFT clock to the receiving unit, the frequency of the pilot signal added by the receiving unit A 210 ₁ is FFT.
It is possible to synchronize with the clock. In that case, as shown in FIG. 11, by calculating and obtaining the absolute value of the complex data of the FFT frequency sample points corresponding to the frequency of the pilot signal, P _c (l ) Can be obtained.

Subsequently, the signal synthesizing circuit 520 outputs the I-axis on the frequency axis output from the FFT circuit of each branch, the Q-axis signal S _c (l, m, n), and the output of the SP extraction / transmission path characteristic estimation circuit. The transmission path characteristic signal H (l, m, n) and the pilot signal power detection circuit are operated by the pilot signal level information P _c
(1) is input, one of the equations (123), (128), and (134) is calculated according to the synthesis method to generate a synthesis coefficient, and the signals of each branch are synthesized. Output. The signal synthesized by the synthesis circuit 520 is input to the determination / identification circuit 530, and the data is demodulated after the determination / identification of the phase point is performed.

Next, a differential modulation type OFDM signal diversity receiving apparatus will be described.

Here, as an example, the case where differential phase modulation such as DQPSK or D8PSK is used for modulation of each carrier will be described. Differential phase modulation OFD
Unlike the case of the OFDM signal of the synchronous modulation system, the M signal does not use the pilot serving as the demodulation reference. First,
The principle of demodulating the differential phase modulation wave will be described.

(Principle of Demodulation of Differential Phase Modulated Wave) The transmission signal is S (m, n), and the frequency characteristic of the transmission line is H (l, m,
n), the received signal Sr (l, 1,
m and n) are represented by the following equation (201).

[0145]

[Equation 59] Here, 1 is a branch number, m is a carrier number, and n is a symbol number. When demodulating a differential phase-modulated wave, a method of multiplying the current symbol by the complex conjugate of the previous symbol and determining the resulting phase value is generally performed.
Therefore, the product D _r (l, m,
n) is

[0146]

[Equation 60] Becomes

Substituting the above equation (201) into the above equation (202),

[0148]

[Equation 61] Is obtained.

On the other hand, the transmission signal S (m, n) has the following (20
It can be expressed by the equation 4).

[0150]

[Equation 62] Here, if the change in the transmission path characteristics in one symbol time is negligible as shown in the following equation (205), the above equation (203) can be rewritten as the following equation (206). it can.

[0151]

[Equation 63]

[0152]

[Equation 64] Further, in differential phase modulation, the absolute value of each carrier to be transmitted is always constant, and therefore the following equation (207) is established.

[0153]

[Equation 65] Then, by substituting the equation (207) into the equation (206),

[0154]

[Equation 66] Is obtained.

Further, the above equation (208) is transformed into the following (20)
When it is put as in the equation (9), A (l, m, n) becomes
It is represented by the equation (10).

[0156]

[Equation 67]

[0157]

[Equation 68] Here, if the phase difference from the previous symbol is rewritten as Δφ (m, n) as shown in equation (211), the above (209)
The equation is represented by the following equation (212). When diversity reception is not performed, the I-axis component of D _r (l, m, n),
Data can be demodulated by obtaining and determining Δφ (m, n) from the arctangent calculation of the Q-axis component.

[0158]

[Equation 69]

[0159]

[Equation 70] The differential modulation OFDM signal diversity receiver shown in this example is capable of performing diversity reception by three combined reception methods, as in the case of the synchronous modulation OFDM signal diversity receiver described above. Here, first, conditions common to these three combined receptions will be described.

(Conditions Common to Each Combining Method) In diversity reception of a differential modulation signal, it is general to perform diversity combining after differential demodulation for each branch.
In this case, since the phase difference between the branches is removed by the differential demodulation processing, the weighting coefficient at the time of combining becomes a real number unlike the case of the synchronous modulation method. Further, since only the phase of the signal after the differential demodulation is detected and determined, the absolute value of the signal after the differential demodulation does not need to be standardized as in the synchronous modulation method.

First, the received signal is combined at the receiving antenna output or the LNA output which is not affected by the AGC amplifier and cable loss in the receiving section, and the AGC amplifier arranged before the A / D converter in the OFDM demodulating section. Think about when. Receive antenna output or LNA output signal is S
_r (l, m, n), the signal after the differential demodulation is D _r (l, m,
n), a synthesis coefficient W _r (l, m, n) at the time of synthesis of received signals in the signal synthesis unit, and an output signal of the signal synthesis unit is D
_{If o} (m, n), the following expression (213) is established.

[0162]

[Equation 71] Next, AGC amplifier in the receiver, cable loss, OFDM
Consider a case where received signals are combined in a signal combining unit having different gains between the branches due to the influence of the AGC amplifier arranged in the preceding stage of the A / D converter of the demodulation unit. The complex amplitude of each branch and each carrier as a result of FFT of the signal from each branch at the input of the signal combining unit is S _c (l,
m, n), and the signal after differential demodulation by multiplying the complex conjugate of the previous symbol for each branch and each carrier, D _c
If (l, m, n), the following equation (214) is established from the above equation (202) in the same manner as the above equation (110).

[0163]

[Equation 72] Substituting the above equation (202) into the above equation (214),

[0164]

[Equation 73] Is obtained.

Here, the above equation (215) is transformed into D _r (l,
Solving for m, n),

[0166]

[Equation 74] Is obtained. Further, in the above equation (213), the above (21
Substituting equation 6),

[0167]

[Equation 75] Is obtained.

Next, the synthesis coefficient in the signal synthesis unit is set to W
_{If c} (1, m, n),

[0169]

[Equation 76] Is established. Therefore, the above equation (217) and the above (21
From the equation (8), W _c (l, m, n) is represented by the following equation (219).

[0170]

[Equation 77] As described above, the synthesis coefficient W_c(L, m, n) is
The received signal to the AGC amplifier or cable loss in the receiver.
Lost, placed before the A / D converter in the OFDM demodulator
Receive antenna output not affected by AGC amplifier
Is a combination coefficient W when combining at the output of the LNA_r
Calculate (l, m, n) and then use equation (219) above
By converting it, the receiver's AGC amplifier and cable
Loss, placed before the A / D converter in the OFDM demodulator
Due to the influence of the AGC amplifier,
When the received signals are combined in the
Growth factor W _c(L, m, n) can be obtained.

Next, an example of calculating the combining coefficient in each combining receiving method applicable to the differential modulation type OFDM signal diversity receiving apparatus will be described.

First, an example of calculating the combination coefficient when the selective combining method is applied as the combining receiving method will be described.

(Case of Selective Combining) First, the received signal is the AGC amplifier of the receiving section, the cable loss and the A of the OFDM demodulating section.
Consider a case of combining at the output of the receiving antenna or the output of the LNA when it is not affected by the AGC amplifier arranged in the preceding stage of the / D converter. The selective combining is a method of selecting and outputting a signal from the branch having the highest CNR, that is, the largest amplitude for each carrier. In the case of the differential modulation method, the signal from the branch having the largest absolute value of the signal after the differential demodulation may be selected.
20) is established.

[0174]

[Equation 78] Next, AGC amplifier in the receiver, cable loss, OFDM
Consider a case where the received signals are combined in the signal combining unit having different gains between the branches due to the influence of the AGC amplifier arranged before the A / D converter in the demodulation unit. In the case of selective combining, the above expression (219) is not applied to the above expression (220), and the gain difference between the branches is considered in the comparison between the branches of the absolute value of the signal after the differential demodulation. Since it is necessary, it is expressed by the following equation (221).

[0175]

[Equation 79] Next, the case of equal gain combination will be described.

(In case of equal gain combination) The equal gain combination is a method of combining each branch with equal gain for each carrier. In the diversity combination of the differential modulation signals, the signal D _r (1, m, n) after the differential demodulation is weighted and combined. D _r (l, m, n) is expressed by the above equation (212), and the detected phase difference amount Δφ (m, n) is thermal noise or transmission line characteristic H (l, m, n). Due to the effect of the time change of
Rewrite the equation 2) as the following equation.

[0177]

[Equation 80] Here, the absolute value A (l, m, n) of D _r (l, m, n)
Is the squared value of the amplitude of each carrier of the received signal as shown in the above equation (210), and therefore the synthesis coefficient W
_r (l, m, n) is set as in the following equation (223).

[0178]

[Equation 81] Next, by substituting the equation (223) into the equation (213),
When organized,

[0179]

[Equation 82] Is obtained.

In the above expression (224), the absolute value of the differential demodulated signal in each branch is standardized, further weighted with the amplitude absolute value of each carrier before differential demodulation, and combined between the branches. It means that in the case of equal gain combination, the weighting coefficient Wr (l, m, n) can be expressed by the above equation (223).

Next, due to the effects of the AGC amplifier in the receiving section, the cable loss, and the AGC amplifier arranged in the preceding stage of the A / D converter in the OFDM demodulating section, the received signal is received by the signal combining section having different gains between the branches. Consider the synthesis coefficient W _c (l, m, n) in the case of synthesis. First, above (2
Substituting the above equation (223) into equation (19),

[0182]

[Equation 83] Is obtained.

Next, the above expression (215) is converted into the above expression (225).
Substituting into the formula, D _r (l, m, n) is D _c (l, m, n)
By rewriting to, the following equation (226) is obtained.

[0184]

[Equation 84] Next, the case of square combination will be described.

(In the case of square combination) First, the received signal is output from the receiving antenna that is not affected by the AGC amplifier and cable loss in the receiving section, and the AGC amplifier arranged in the preceding stage of the A / D converter in the OFDM demodulating section. , LNA output at the output. As described above, the absolute value A (l, m, n) of the complex amplitude D _r (l, m, n) of each carrier after the differential demodulation is equal to the received signal as shown in the above equation (210). Since it is the squared value of the absolute value of each carrier, the square combination is performed by combining them as they are. That is, the following expression (227) is established.

[0186]

[Equation 85] Next, AGC amplifier in the receiver, cable loss, OFDM
Due to the influence of the AGC amplifier arranged in the preceding stage of the A / D converter of the demodulation unit, a synthesis coefficient W _c (l,
Consider m, n). The above (227) is added to the above (219) formula.
Substituting the expression,

[0187]

[Equation 86] Is obtained. In the strict sense, the square combination of diversity reception of the differential modulation method does not match the so-called maximum ratio combination of C / N maximum.

Next, a device configuration example of the differential modulation type OFDM signal diversity receiving device will be described. still,
The configuration of the receiving unit has the same configuration as that of the single carrier system shown in FIGS. Further, the configuration of the OFDM demodulation / signal combining unit is basically the same as that of the above-described diversity receiver for synchronous modulation type OFDM signal, but the FF in the OFDM demodulation unit is
The configuration after the T circuit is different. The OFDM demodulation unit of the diversity receiver for synchronous modulation type OFDM signal is provided with a frame synchronization detection circuit for performing synchronous detection and an SP extraction / transmission path characteristic estimation circuit.
The OFDM demodulation unit of the M signal diversity receiving apparatus is not provided with them, but instead is provided with a differential demodulation circuit 5122 that performs a differential demodulation process.

Therefore, here, different parts after the FFT circuit will be described.

In FIG. 9, the I-axis and Q-axis signals on the frequency axis output from the FFT circuit 5118 are each divided into two and supplied to the differential demodulation circuit 5122 and the pilot signal power detection circuit 5119. The pilot signal power detection circuit 5119 operates in accordance with the synchronous modulation method OFDM.
The description is omitted because it is the same as the case of the OFDM demodulation / signal combining unit of the signal diversity receiving apparatus. The I-axis and Q-axis signals on the frequency axis input to the differential demodulation circuit 5122 are
The signal is multiplied by the complex conjugate data of the previous symbol and is supplied to the signal synthesis circuit 520 as a signal D _c (l, m, n) after differential demodulation. The signal synthesis circuit 520 receives the differential demodulated signal D _c (l, m, n) from each branch and the pilot signal level information P _c (l) from the pilot signal power detection circuit 5119, respectively. Depending on the synthesizing method of (22), any of the equations (221), (226), and (228) is calculated to generate a synthesis coefficient, and the signals of the respective branches are synthesized and output. The combined signal is input to the determination / identification circuit 530, the phase of the input signal is determined / identified, and the data is demodulated.

According to the above-described embodiment, in the receiving units A210 _{1 to} L210 _L of each branch, the pilot signal is inserted outside the band of the received signal, and the OFDM demodulation / signal combining unit 500 refers to the level of the pilot signal. Therefore, the receiving antenna A110 in each of the branches 1 to L
The level change amount from the output end of _{1 to} L110 _{L to} the input end of the OFDM demodulation / signal combining unit 500 is detected, and the reception antenna output level of each branch _{1 to L} is estimated from the detection result. Therefore, the OFDM demodulation / signal combining unit 50
Even if the input signal level of 0 is not proportional to the C / N of the received signal, the OFDM demodulation / signal combining unit 500 combines or selects the received signals from the branches 1 to L at an optimum combining ratio. It becomes possible.

In the above example, the receiving units A200 ₁ , 21
The pilot signal multiplex functions of 0 _{1 to} L200 _L and 210 _L serve as the reference signal multiplex means, and the functions of the level detection units A412 ₁ to L412 _L of the signal synthesis unit 400 include the received signal level estimation unit, the reference signal detection unit, The OFDM demodulation units A501 _{1 to} L501 of the OFDM demodulation / signal combining unit 500 correspond to the amplification degree estimation unit and the level attenuation amount estimation unit.
The pilot signal power detecting circuit 5119 of _L serves as a reference signal detecting means, and the level estimating function of the signal combining circuit 520 of the same section 500 serves as an amplification degree estimating means, a level attenuation amount estimating means, and a level change amount estimating means. Correspond. Also, the receiving units A200 ₁ , 210 _{1 to} L200 _L ,
The positions of the 210 _L pilot signal generator 25 and the adder 24 correspond to the reference signal arrangement means, and the synchronous modulation OFDM
The transmission path characteristic estimation function of the SP extraction / transmission path characteristic estimation circuit 5121 of the OFDM demodulation sections A501 _{1 to} L501 _L of the signal OFDM demodulation / signal synthesis section 500 corresponds to the transmission path characteristic estimation means. Further, the signal combining circuit 52 of the same section 500
The pilot signal power calculation function of 0 is reference power calculation means,
It corresponds to the reference signal power amplitude converting means.

[0193]

As described above, according to the first aspect of the present invention.
According to the present invention described in No. 1, the reference signal (hereinafter, referred to as a pilot signal) is multiplexed outside the band of the reception signal received by each reception antenna, and the level of the multiplexed pilot signal is referred to, so that each reception antenna Since it is possible to detect the amount of level change from the output end to the input end of the signal combining stage that performs signal combining, the level of the received signal output from each receiving antenna or the C / N of the received signal must be estimated from this detection result. You can As a result, it becomes possible to combine or select the reception signals from the respective reception antennas at the optimum ratio. Further, according to the present invention, since the pilot signal for estimating the received signal level is only multiplexed outside the band of the received signal, it is possible to provide an optimal diversity receiving device without inviting complexity of the device.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a single carrier diversity receiver according to a first embodiment of the present invention.

FIG. 2 is a diagram (No. 1) showing an example of the configuration of a receiving unit.

FIG. 3 is a diagram (part 2) illustrating an example of the configuration of a receiving unit.

FIG. 4 is a diagram (No. 3) showing an example of the configuration of a receiving unit.

FIG. 5 is a diagram (part 1) illustrating an example of the configuration of a signal combining unit.

FIG. 6 is a diagram (No. 2) showing an example of the configuration of a signal synthesizing unit.

FIG. 7 is a configuration diagram of an OFDM diversity receiving apparatus showing a second embodiment of the present invention.

FIG. 8 is a diagram (for synchronous modulation OFDM signal) showing an example of the configuration of an OFDM demodulation / signal combining unit.

FIG. 9 is a diagram (for differential modulation OFDM signals) showing an example of the configuration of an OFDM demodulation / signal combining unit.

FIG. 10 is an explanatory diagram showing a case where a pilot carrier frequency is asynchronous with an OFDM signal.

FIG. 11 is an explanatory diagram showing a case where the pilot carrier frequency is synchronized with the OFDM signal.

[Explanation of symbols]

21, 29, 213, 5101, 5104 Band pass filter (BPF) 22 RF amplifier (LNA) 23, 4121, 4126 Distributor 24 Adder 25 Pilot signal generator 26, 5105 Variable gain amplifier (AGC amplifier) 27 Local oscillator 28, 413 ₁ , 413 ₂ , 413 _L , 5102, 51
09, 5110 multipliers 100 ₁ , 110 ₁ receiving antennas A 100 ₂ , 110 ₂ receiving antennas B 100 _L , 110 _L receiving antennas L 200 ₁ , 210 ₁ receiving units A 200 ₂ , 210 ₂ receiving units B 200 _L , 210 _L Receiver L 210 IF amplifier 211 Level detector 212 Control voltage generator 300 ₁ , 300 ₂ , 300L, 310 ₁ , 310 ₂ ,
310 _L cable 400 Signal combining unit 411 ₁ Phase adjusting unit A 411 ₂ Phase adjusting unit B 411 _L Phase adjusting unit L 412 ₁ Level detecting unit A 4122 ₂ Level detecting unit B 412 _L Level detecting unit L 414 Combined coefficient generating circuit 415 Combined Device 4122 Pilot signal extraction BPF 4123 Received signal extraction BPF 4124, 4125 Level detector 500 OFDM demodulation / signal combining unit 501 ₁ OFDM demodulation unit A 501 ₂ OFDM demodulation unit B 501 _L OFDM demodulation unit L 5103 Local oscillator 5106 A / D converter 5107, 5108 Fixed pattern generator 5111, 5112 LPF 5113, 5114 4: 1 decimation circuit 5115 Frequency phase error detection circuit 5116 Complex phase rotator 5117 Effective symbol period extraction circuit 5118 FFT circuit 5119 Pilot No. power detection circuit 5120 frame synchronization detection circuit 5121 SP extraction, channel characteristics estimation circuit 520 a signal combining circuit 530 determination and identification circuit

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Tetsuomi Ikeda             1-10-11 Kinuta, Setagaya-ku, Tokyo, Japan             Broadcasting Association Broadcast Technology Institute (72) Inventor Shunji Nakahara             1-10-11 Kinuta, Setagaya-ku, Tokyo, Japan             Broadcasting Association Broadcast Technology Institute F term (reference) 5K059 CC03 DD02 DD31 DD44

Claims (11)

[Claims] 1. A diversity receiving apparatus for receiving a signal modulated by a single carrier by using a plurality of receiving antennas, and selecting or combining the received plurality of received signals, the diversity receiving apparatus outputs the signals. Reference signal multiplexing means for multiplexing the reference signal outside the frequency band of the received signal, and the received signal level for estimating the level of the received signal output from each receiving antenna with reference to the signal level of the multiplexed reference signal A diversity receiver having an estimating means. 2. The diversity receiving apparatus according to claim 1, wherein the reference signal multiplexing means generates and multiplexes the reference signal of a predetermined level in front of an amplifier that amplifies the received signal received to a certain value. A diversity receiver having a disposing means. 3. The diversity receiving apparatus according to claim 1, wherein the received signal level estimating means detects the reference signal, and the received signal amplified by the amplifier based on the detected reference signal. Amplification degree estimating means for estimating the amplification degree of, and a level attenuation amount for estimating the attenuation amount of the signal level from the output of the receiving section including the amplifier to the input of the signal combining section for selecting or combining a plurality of received signals A diversity receiving apparatus, comprising: an estimating unit, which estimates the level of a received signal output from each receiving antenna based on the estimated amplification degree and the attenuation amount of the signal level. 4. The diversity receiving apparatus according to claim 1, wherein the received signal before the reference signal is multiplexed is detected, and the multiplexed signal is amplified based on the level of the detected received signal. 5. The diversity receiver according to claim 1, wherein the reference signal is multiplexed, and then the received signal amplified by the amplifier is extracted by the filtering means, and the multiplexed signal is extracted based on the level of the extracted received signal. A diversity receiver that amplifies. 6. The diversity receiving apparatus according to claim 1, wherein only the received signal is extracted from the signal after the reference signal is multiplexed by the filtering means, and the multiplexed signal is amplified based on the level of the extracted received signal. Diversity receiver. 7. A synchronous modulation type OFDM (Orthogonal Frequency Division Multiplexing) signal in which pilots are dispersedly inserted and transmitted in a specific carrier is received using a plurality of receiving antennas, and the received plurality of received signals are received. In a diversity receiving device for selecting or combining, refer to reference signal multiplexing means for multiplexing a reference signal generated outside the frequency band of the received signals output from the plurality of receiving antennas, and a signal level of the multiplexed reference signals. And a OFDM signal level estimating means for estimating the level of the OFDM signal output from each receiving antenna. 8. The diversity receiving apparatus according to claim 7, wherein the OFDM signal level estimating means detects a reference signal by the reference signal detecting means, and the received signal amplified by the amplifier based on the detected reference signal. Amplification degree estimating means for estimating the amplification degree of the signal level, level attenuation amount estimating means for estimating the signal level attenuation amount from the amplifier to the input of the signal combining section for selecting or combining a plurality of received signals, and the signal A level change amount estimating means for estimating the level change amount by the AGC circuit for adapting to the input range of the A / D converter provided in the synthesizing unit, and the estimated level change amount and reception from each antenna. Each receiving antenna is based on the transmission path characteristics obtained from the data of the pilot carrier of the OFDM signal obtained by fast Fourier transforming the signal. OFD to be al output
A diversity receiver characterized by estimating the level of an M signal. 9. The diversity receiver according to claim 7, wherein differential modulation is used instead of synchronous modulation for data modulation of each carrier of an OFDM (Orthogonal Frequency Division Multiplexing) signal. 10. The diversity receiving apparatus according to claim 9, wherein the OFDM signal level estimating means detects the reference signal, and the reception signal amplified by the amplifier based on the detected reference signal. Amplification degree estimating means for estimating the amplification degree of the signal level, level attenuation amount estimating means for estimating the signal level attenuation amount from the amplifier to the input of the signal combining section for selecting or combining a plurality of received signals, and the signal A level change amount estimating means for estimating the level change amount by the AGC circuit for adapting to the input range of the A / D converter provided in the synthesizing unit, and the estimated level change amount and reception from each antenna. Of the OFDM signal output from each receiving antenna based on the level of each carrier of the OFDM signal obtained by fast Fourier transforming the signal Diversity receiving apparatus characterized by estimating the bell. 11. The diversity receiving device according to claim 7, wherein after converting a reception signal from each reception antenna into carrier data on a frequency axis, a frequency sample on a frequency axis corresponding to the frequency of the reference signal. A diversity receiving apparatus comprising: reference power calculation means for calculating the power of the reference signal by integrating the power of carrier data in the vicinity of a point; and reference signal power amplitude conversion means for converting the power of the reference signal into an amplitude.