JP3228311B2 - Receiver - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a receiving apparatus suitable for use in a receiving section for receiving and demodulating a signal in a mobile terminal such as a cellular telephone.

[0002]

2. Description of the Related Art In recent years, a spread spectrum communication system (hereinafter, referred to as a spread spectrum communication system) that performs communication by spreading a modulated wave in a spectrum band several hundred to several thousand times wider than the bandwidth of information.
The SS (Spectrum Spread) method) has attracted attention. In this SS system, a carrier is modulated by a PN sequence (PN code) (pseudo-noise code) on a transmitter side to spread a frequency spectrum, and the spread spectrum signal is transmitted to a receiver. It has been made like that. Then, in the receiver, after undergoing a despreading (correlation) process using a PN sequence generated by a code generator having the same structure as the transmitter, demodulation (baseband demodulation)
Thus, data is obtained.

In the SS system, in order to demodulate a signal in a receiver, the pattern of the PN sequence needs to match as described above, and its phase must also match. That is, communication can be established only when the PN sequence used on the transceiver side is the same sequence and the phases match. If this property is used, it is possible to use a large number of channels (circuits) by using the same frequency band and by using different PN sequences. A method of realizing channel identification by a PN sequence and performing multiple access (multiplexing) is CDMA (Code Division Multiple Access: Code Devis).
Ion Multiple Access) method.

FIG. 7 is a block diagram showing an example of the configuration of a conventional cellular telephone to which the CDMA system is applied. To the multipliers 1 and 2, a signal S _{in obtained} by converting a signal from a transmitter of a base station into an IF frequency (intermediate frequency) is supplied through an input terminal. Here, this I
The F frequency and f _in.

On the other hand, from a voltage control oscillator (VCO) 3, corresponding to a frequency error Δf, which will be described later, supplied from a frequency error detector 33 via a loop filter (LF) 25 composed of a low-pass filter, IF frequency f _in a frequency substantially equal to f _VCO signal S _{v co} is output to the multiplier 1 and the phase shifter 4. The phase shifter 4 shifts (rotates) the phase of the signal S _vco from the VCO 3 by π / 2, and
Output to

[0006] The multiplier 1 multiplies the signal S _in by S _VCO ,
A signal component having the same phase as the phase reference point (hereinafter, referred to as an I-channel signal) is output. At the same time, the multiplier 2 outputs the signal S
_In is multiplied by the signal S _VCO shifted in phase by π / 2 to output a signal component orthogonal to the phase reference point (hereinafter, referred to as a Q channel signal). That is, quadrature detection is performed by the multipliers 1 and 2 and the phase shifter 4.

The signals of the I and Q channels are supplied to a despreader 3
1. The data is input to the demodulation processing unit 12 composed of a data demodulation unit 32, a frequency error detection unit 33, a data processing unit 34, and a control circuit 35. First, the despreader 31 uses the same PN sequence as the transmitter side. Despread. The I and Q channel signals (despread data) despread by the despreader 31 are supplied to a data demodulation unit 32 and a frequency error detection unit 33. In the data demodulation unit 32, I and Q
Data is demodulated using the channel signal and output to the data processing unit 34.

The data processing section 34 includes a data demodulation section 32
From the output data, the voice information and control information sent from the transmitter are extracted based on a predetermined format. The audio information is supplied to a subsequent circuit (not shown) and is subjected to predetermined processing. The control information is supplied to the control circuit 35, and the control circuit 35 performs a predetermined process based on the control information. Further, the control circuit 35 controls the despreader 31, the data demodulator 32, and the frequency error detector 33.

Here, the signals of the I or Q channels output from the multipliers 1 and 2 respectively include the frequency f _VCO of the signal S _VCO output from the _{VCO 3} and the frequency (IF frequency) f _{in of the} input signal S _in. Are the same, a baseband signal (a signal with an IF frequency of 0 Hz) is obtained.

However, cellular telephones are often used, for example, in a running car or train.
In this case, due to the Doppler effect, the frequency f _in of the signal S _in is, deviates from the original value. Thus, the frequency f
A _VCO and f _in is not the same, the difference, that is an amount corresponding to the frequency error _{△ f (= f in -f VCO} ), each signal of the I or Q channel output from the multiplier 1 or 2, the original Deviates from the baseband position.

If the deviation becomes large, the data demodulation section 32 cannot accurately demodulate data.

Therefore, the frequency error detection unit 33 calculates the I and Q channel signals despread by the despreader 31
Detect the frequency error Δf and set it to 0 Hz,
The frequency f _VCO of the signal S _VCO output from the _{VCO 3} is controlled via the LF 25.

That is, multipliers 1 and 2, phase shifter 4, despreader 31, frequency error detector 33, LF25, and V
The loop composed of CO3 forms a so-called PLL, and in this system, the VCO 3 is controlled so that the frequency error Δf becomes 0 Hz.
In step 2, accurate data demodulation is performed.

The signal transmitted from the transmitter of the base station includes a data channel composed of communication data such as voice information and a pilot channel composed of a predetermined fixed value. For detecting the error Δf, a signal of a pilot channel is usually used.

In a cellular telephone, a plurality of routes (e.g., a radio wave transmitted from a transmitter of one nearby base station is directly received, or a radio wave is received by being reflected by a reflector such as a building). Path) is received (hereinafter, a path is formed).

Further, when the cellular telephone is located at substantially the same distance from a plurality of base stations, a path is formed with each of the plurality of base stations.

Therefore, in the cellular telephone shown in FIG. 7, searcher 14 converts the I or Q channel signal output from multiplier 1 or 2 and the PN sequence into
By multiplying the phase by shifting the phase within one cycle of the PN sequence, that is, by taking the correlation between the I and Q channel signals and the PN series within one cycle of the PN sequence, a plurality of paths ( Each of the multipaths is searched and identified, and, for example, those having the highest reception level (highest correlation value) are despread by the despreader 31.

However, when the cellular telephone is located far from the base station, there is a case where a sufficient S / N cannot be obtained even if the path having the highest reception level is selected.

Therefore, as a receiving method for improving the S / N, RA using a multipath formed along a different propagation path between one base station and a cellular telephone for reception is used.
The KE receiving method is known.

Here, the RAKE receiving method will be briefly described. For details on the RAKE reception method, see "Introduction to Spread-Spectrum Antimultipath."
Techniques and Their Application to Urban Digital
Radio ", GLTurin and the like.

FIG. 8 shows how a plurality of paths are formed between one base station and a cellular telephone. As shown in the figure, a transmission signal from a base station (transmitter) is transmitted along a different propagation path, with a path i having a delay time t _i and a signal strength a _i different depending on the propagation path (where i = 0, i = 0,
1,..., K) and reaches the cellular telephone (receiver).

Now, the transmission signal s (t) is expressed by the following equation: s (t) = Re [σ (t) · exp (iω ₀ t)] (where Re [x] means the real part of x) The received signal r (t) is given by the following equation. r (t) = Re [ρ (t) · exp (iω 0 t)] + n (t) _{here, ρ (t) = Σa k} · σ (t-t k) · exp (j
In θ _k ), Σ means the summation from k = 0 to K−1.

When the received signal r (t) is passed through a so-called matched filter (hereinafter referred to as MF), the output of the received signal r (t) corresponds to the delay time of the path as shown in FIG. , A signal having a plurality of peaks. If the spreading code sequence is uncorrelated to the same delayed code sequence, each peak will be completely independent.

According to the above-mentioned literature, the optimum receiver can be expressed by the following equation based on the delay time of the path and the signal strength. w = Σlog _e I ₀ (2 · a ′ _k × x ′ _k / N _e ) In the above equation, I ₀ (x) is a Bessel function, and for sufficiently large x, the equation log _e I ₀ ( x) Since approximation of ≒ x holds, w can be expressed by the following equation. _{w = 2 / N 0 · Σa} 'k · x' k

This equation is a transversal filter (hereinafter, referred to as TF) composed of a delay line, a multiplier, and an adder shown in FIG. 9A. In FIG. 9B, four peaks of the received signal shown in FIG. 9A are added to predetermined coefficients α _{0 to} α ₃ corresponding to the characteristics of the transmission path.
(However, α _{0 to} α ₃ are coefficients other than 0) are multiplied, and other parts are multiplied by 0, and the multiplication result is added. It shows that the ingredients can be strengthened.

The RAKE receiving method is a method based on this principle. Therefore, according to the RAKE receiving method, FIG.
The received signal shown in (A) is converted to a TF as shown in FIG.
As shown in FIG. 9 (C), the signal component is further strengthened as compared with noise, that is, 1 with improved S / N.
It is possible to obtain a signal having two main peaks.

FIG. 10 shows a bit error rate when a signal of the DPSK modulation method is received by the above-mentioned RAKE reception method. From the figure, when the RAKE reception method is not applied, if there is Rayleigh fading, the S / N
It can be seen that the bit error rate is not improved even if the error rate is good, but the bit error rate is significantly improved by performing RAKE reception.

Next, FIG. 11 shows a configuration of an example of a cellular telephone to which the RAKE receiving method is applied. In the figure, parts corresponding to those in FIG. 7 are denoted by the same reference numerals, and the multipliers 1, 2, VCO3,
The description of the phase shifter 4 and the LF 25 is omitted. Further, the signals input to the MF 41 are two signals of the I or Q channel output from the multiplier 1 or 2 shown in FIG. 7, respectively. Therefore, actually, two signal lines are required. In FIG. 11, since the figure becomes complicated,
Only one signal line is shown.

The MF 41 detects a delayed path and its signal strength from the signals (I and Q channel signals) from the multipliers 1 and 2. That is, the MF 41 outputs signals from the multipliers 1 and 2 (I and Q channel signals).
And the correlation with the PN sequence are calculated within the period of the PN sequence. As a result, a multipath received signal from one base station is converted into a signal having a plurality of peaks as shown in FIG. 9A (hereinafter referred to as a correlation waveform) in accordance with the path delay time and signal strength. Signal).

In the correlation waveform signal shown in FIG. 9 (A), the received signal is converted from its direct wave into time t ₁ , t ₂ , t ₃ (where,
t ₃ is a time that is equal to the maximum delay spread T _M in FIG. 9A).

This correlation waveform signal is supplied to the TF 42 and the sounder demodulation circuit 43.

The sounder demodulation circuit 43 detects the sounder inserted in the signal transmitted from the base station.

Here, the sounder is information for estimating the characteristics of the transmission path, and as shown in FIG. 9D, a signal transmitted from the base station is regularly (eg, one frame). Are inserted periodically (periodically) such as several tens.

The sounder demodulation circuit 43 estimates the characteristics of the transmission path from the detected sounder. Since the delay time and the signal strength of the path change according to the characteristics of the transmission path, the sounder demodulation circuit 43 estimates the characteristic of the transmission path, and then, based on the estimation result, determines the change of each path when multipath is received. The calculated delay time and signal strength are calculated, and a coefficient (weighting coefficient) of the TF 42 is determined based on the calculation result.
Feed to 2.

The TF 42 is, as shown in FIG.
A delay line for delaying the correlation waveform signal from the MF 41, a multiplier for multiplying the correlation waveform signal delayed by the delay line with a coefficient from the sounder demodulation circuit 43, and an adder for adding the output of the multiplier Have been. In the TF42, the delay interval of the delay line, that is, the interval of its tap is 1 / W
When a correlation waveform signal in the range of the time T _M is input from the MF 41, the product sum operation of the correlation waveform and the coefficient from the sounder demodulation circuit 43 is performed.
(C) to the as shown, has a main peak in time T + T _M, and outputs an enhanced signal S / N in the demodulation processing unit 12.

The demodulation processing section 12 performs the same processing as that described with reference to FIG. 7, and outputs demodulated data having an improved S / N.

By the way, recently, as a receiving method for further improving S / N, in addition to a plurality of paths from one base station, two or more paths among paths from each of the plurality of base stations are used. A method of demodulating and combining the demodulation results (hereinafter referred to as a diversity RAKE receiving method) has been proposed.

FIG. 12 shows an example of the configuration of a cellular telephone to which the diversity rake receiving method is applied. In the figure, the same reference numerals are given to portions corresponding to the case in FIG.

This cellular telephone has a despreader 31, a data demodulator 32, and a frequency error detector 3 surrounded by a dotted line in FIG.
3, a plurality of fingers (fi) configured similarly to the demodulation processing unit 12 including the data processing unit 34 and the control circuit 35.
nger) 21a to 21c, and the demodulated data or frequency error output from each of them is combined by the data combiner 22 or the frequency error combiner 23.

It should be noted that I from each of the multipliers 1 and 2
Alternatively, the signals of the Q channel are output from fingers 21a to 21c.
In addition, it is also supplied to the searcher 51. In searcher 51, I and Q channel signals,
By correlating with the PN sequence within one cycle of the PN sequence, each of the plurality of paths received by the cellular telephone is searched and identified, and the path to be demodulated by each of the fingers 21a to 21c is determined. The delay times of the paths for which demodulation is determined are determined by the fingers 21a to 21c.
Supplied to Thereby, the fingers 21a to 21c
In each case, the demodulation is performed in the same manner as in FIG. 7 based on the delay time of the path output from the searcher 51.

From each of the fingers 21a to 21c, demodulated data or a frequency error obtained by demodulating each path is given by
Data combiner 22 or frequency error combiner 23
Is output to The data combiner 22 includes the finger 21
The demodulated data output from each of a to 21c are combined (added) and output (hereinafter, the combined demodulated data is referred to as combined demodulated data). As a result, demodulated data with an improved S / N can be obtained.

The frequency error combiner 23 is provided with a frequency error detecting section 33 constituting the fingers 21a to 21c.
Combining (adding) frequency error Δf output from FIG. 7
(Hereinafter, the synthesized frequency error is referred to as a synthesized frequency error) and is output to the VCO 3 via the LF 25.

Here, in the searcher 51, one suitable for combining among a plurality of paths forming a multipath (for example, the level (corresponding to the signal intensity of the path, The finger having the higher correlation value) is selected as necessary, and the fingers 2 are demodulated so as to demodulate this path.
Each of 1a to 21c (demodulation processing units 126a to 126c) is controlled.

Accordingly, when the cellular telephone has three fingers 21a to 21c, for example, as shown in FIG. 7, three paths are selected as needed from a plurality of paths in descending order of level. Each of the three passes
Demodulation is performed by each of the fingers 21a to 21c.

By the way, recently, as described above, the CD
As an application of the cellular telephone system using the MA system,
There has been proposed a system that can use a cellular telephone not only outdoors but also indoors such as a building where radio waves (signals) from a base station are difficult to reach directly. For example, PCS (Personal Communication Services),
Distributed Antenna
The method using a) is one of them.

Here, FIG. 13 shows an example of the configuration of a system using a distributed antenna. In this system, a signal from a base station transmitter is output as radio waves from a base station antenna and output via a cable to a distributed antenna installed in a building. I have.

When the cellular telephone is located outdoors, the radio wave output from the antenna of the base station is received. When the cellular telephone is located in a building, the radio wave transmitted from the transmitter is received. A signal is received via a distributed antenna.

As shown in FIG. 13, the distributed antenna includes a plurality of indoor antennas mounted at required positions in a building and a P antenna connecting them.
The delay circuit delays the path by a time τ longer than the time interval between bits constituting the N sequence (the reciprocal of the bit rate of the PN sequence (eg, 8 Mbps or 16 Mbps)).

In a building (indoor) where such distributed antennas are installed, in addition to direct paths from a plurality of indoor antennas (hereinafter, referred to as direct paths), they may be, for example, a wall or the like. Although a path reflected by an obstacle in the building (hereinafter, referred to as a reflection path) is also formed, the distance between the indoor antenna and the cellular phone is short. The difference between the position of the direct path and the position of the reflection path) is generally shorter than the time τ described above.

Therefore, the direct path and the reflection path cannot be separated (identified) by PN sequences having different phases. Therefore, according to the distributed antenna, a multipath having the same number of separable paths as the number of indoor antennas and a delay time τ of each path is substantially formed in the building. .

Therefore, the RAKE shown in FIGS.
When a cellular phone of the receiving system or the diversity RAKE receiving system is used in a building where a distributed antenna is installed, the path from the indoor antenna can be received with almost no loss. , Good S / N is obtained.

[0052]

When the cellular telephone of the RAKE receiving system shown in FIG. 11 is used outdoors, as described above, the path delay time and the signal strength are reduced due to the characteristics of the transmission path. As it changes, the sounder (Fig. 9
By inserting (D)) in a sufficient number into the transmission signal and estimating the characteristics of the transmission path with high accuracy, the coefficient of the TF 42 can be made more appropriate.

On the other hand, when this cellular telephone is used indoors where the distributed antenna shown in FIG. 13 is installed, the characteristics of the indoor transmission path are sufficiently stable as compared with those in the outdoors. Therefore, it is considered that the signal strength of the path output from each of the plurality of indoor antennas is substantially equal. In this case, the received path is substantially only the direct path, and the delay time of the path is provided by the delay circuit (FIG. 13). Unlike the outdoors, there is almost no fluctuation.

Therefore, in this case, it is not necessary to estimate the characteristics of the transmission path using a sounder. Inserting a large number of sounders into the transmission signal for this unnecessary processing means that the information to be transmitted is Is degraded in transmission efficiency.

The present invention has been made in view of such circumstances, and aims to improve transmission efficiency without deteriorating S / N.

[0056]

A first receiving apparatus according to the present invention comprises a TF (transversal filter) 11 as a product-sum operation means for multiplying a multipath received signal by a predetermined coefficient and adding the result. A demodulation processing section 12 as demodulation means for demodulating the output of the TF 11; and a bit detection section 13 as detection means for detecting, from the output of the demodulation processing section 12, delay time information relating to delay times of paths constituting a multipath. And the TF 11 determines a predetermined coefficient based on the delay time information detected by the bit detection unit 13.

[0057]

The second receiving apparatus of the present invention includes a searcher 24 as search means for searching for individual paths from a multipath received signal, a demodulation of the paths searched by the searcher 24, and a demodulated data. And a plurality of fingers 21a to 21c as demodulating means for outputting
a data combiner 22 as combining means for combining the demodulated data output from each of a to 21c and outputting the combined demodulated data, and delay time information relating to the path delay time from the combined demodulated data output from the data combiner 22. Bit detection unit 13 as detection means for detecting
Based on the delay time information detected by the bit detection unit 13, a predetermined coefficient is determined, a TF11 as a product-sum operation means for multiplying and adding to the received signal, and whether or not the apparatus is used indoors 24 based on the determination result of the searcher 24 and demodulate the path to the fingers 21a to 21c, or output the TF11 to at least one of the fingers 21a to 21c instead of the path. And a searcher 24 as control means for controlling whether or not the signal is demodulated.

[0059]

According to the first receiving apparatus of the present invention, delay time information relating to the delay time of the paths constituting the multipath is detected from the output of the demodulation processing unit 12, and the multipath and the multipath are detected based on the delay time information. A predetermined coefficient of TF11 to be multiplied by the received signal is determined. Therefore, if the delay time of the path does not change, the delay time information needs to be received only once. For example, compared with the case where information for estimating the characteristics of the transmission path such as a sounder is inserted into the transmission signal, Transmission efficiency can be improved.

[0060]

In the second receiving apparatus of the present invention, delay time information relating to the delay time of the path is detected from the combined demodulated data obtained by combining the demodulated data output from each of the fingers 21a to 21c. Based on this, a predetermined coefficient of TF11 is determined. Then, the searcher 24 detects whether or not the device is used indoors. For example, when the device is used indoors,
At least one of the fingers 21a to 21c demodulates the output of the TF 11 instead of the path. Therefore, S / N
Demodulated data (synthesized demodulated data) can be obtained.

[0062]

Embodiments of the present invention will be described below with reference to the drawings. [First Embodiment] FIG. 1 is a block diagram showing a configuration of a first embodiment of a cellular telephone to which a receiving apparatus of the present invention is applied. 7, the same reference numerals are given to the portions corresponding to those in FIG. 7, and the description of the multipliers 1, 2, VCO 3, the phase shifter 4, and the LF 25 is omitted. Further, the TF 11 and the searcher 14
Are two signals of the I or Q channel output from the multiplier 1 or 2 shown in FIG. 7, respectively. Therefore, although two signal lines are actually required,
One signal line is shown as a representative.

This cellular telephone is for exclusive use in a building (for indoor use only) in which a distributed antenna as shown in FIG. 13 is installed, for example, as shown in FIG. For each predetermined number of frames, such as frames, a delay information bit (for example, a binary representation of the delay time itself or a type of delay time, ^{If the} number is equal to or less than 2 ^n, a frame in which a delay time is represented by n bits, etc.) is inserted at the beginning of the frame. further,
Unlike a transmission signal output from a transmission antenna outside a base station, a sounder is not inserted into a transmission signal output from the distributed antenna.

As described above, since the delay information bit is inserted into the transmission signal at a frequency sufficiently smaller than that of the sounder, the transmission efficiency hardly deteriorates.

In the cellular telephone configured as described above, first, as in the case of FIG.
And 2 output I and Q channel signals. This signal is supplied to the demodulation processing unit 12 via the searcher 14 and the TF 11. The searcher 14 includes the multiplier 1
From the signals (I and Q channel signals) supplied from and 2, each of a plurality of paths constituting a multipath from the distributed antenna is searched and identified as described with reference to FIG. Control is performed to select one path and to cause the demodulation processing unit 12 to demodulate.

The demodulation processing unit 12 demodulates one of the plurality of paths constituting the multipath in accordance with the control of the searcher 14 as described with reference to FIG. 7 (FIG. 11).
The demodulated data is output to the bit detector 13.

The bit detector 13 detects the delay information bits described with reference to FIG. 2 from the demodulated data from the demodulator 12 and outputs the delayed information bits to the TF 11 and outputs the demodulated data obtained by separating the delayed information bits. , Which are output to a subsequent processing circuit (not shown).

The TF 11 is configured in the same manner as the TF 42 of FIG. 11, and when receiving the delay information bit from the bit detector 13, sets the coefficient corresponding to the multipath delay time represented by the delay information bit to the tap.

When the TF 11 sets the tap coefficient by itself, the TF 11 processes the I and Q channel signals from the multipliers 1 and 2 in the same manner as described with reference to FIG. A signal having a peak and an improved S / N is output to the demodulation processing unit 12.

In the demodulation processing unit 12, the S /
When the supply of the signal with the increased N is started, the searcher 14
In place of the path that has been processed according to the control of (1), the signal demodulation processing is started.

That is, after the TF 11 sets its own coefficient, reception is performed by the RAKE reception method.

As described above, the delay information bit is inserted into the transmission signal at a frequency sufficiently smaller than the sounder in place of the sounder, so that the transmission efficiency is prevented from deteriorating. A cellular telephone can be configured without providing a matched filter and a sounder demodulation circuit, which are always required when performing reception by the RAKE reception method.

[Second Embodiment] FIG. 3 is a block diagram showing the configuration of a second embodiment of a cellular telephone to which the receiving apparatus of the present invention is applied. Note that, in the same figure, parts corresponding to those in FIG. 1 are denoted by the same reference numerals. That is, the cellular telephone of FIG.
Is deleted and TF15 is provided in place of TF11, except that the configuration is the same as that of the cellular telephone of FIG.

This cellular telephone, like the cellular telephone of FIG. 1, is exclusively for use in a building in which a distributed antenna as shown in FIG. 13 is installed (for indoor use only). However, a delay information bit and a sounder are not inserted into the transmission signal output from the distributed antenna.

Further, this cellular telephone is designed to be used indoors where the delay time of the multipath provided by the distributed antenna is known in advance, and TF15 is configured in the same manner as TF42 in FIG. A coefficient corresponding to a known delay time interval is set in the tap in advance.

Accordingly, in this case, in TF15, the signals of the I and Q channels from multipliers 1 and 2
The signal is processed in the same manner as described in (B), and a signal having an improved S / N having a main peak at a predetermined timing is output to the demodulation processing unit 12.

Therefore, in this cellular telephone, the reception by the RAKE receiving method is performed immediately after the start of the operation.

As described above, since the coefficient is set in advance to the tap of the TF 15 based on the known delay time, there is no need to insert a delay information bit or sounder into the transmission signal. It is possible to prevent the efficiency from deteriorating. In this case, the bit detector 1
Since the cellular telephone can be configured without providing the device 3, the size of the device can be further reduced.

[Third Embodiment] FIG. 4 is a block diagram showing the configuration of a third embodiment of a cellular telephone to which the receiving apparatus of the present invention is applied. In the figure, the same reference numerals are given to the portions corresponding to those in FIG. 1 or FIG.

This cellular telephone is used outdoors and in FIG.
As shown in FIG. 2, the distributed antenna is also used in a building (indoor) and transmitted from the distributed antenna in which delay information bits (FIG. 2) are inserted as in the first embodiment. A signal is output.

In this cellular telephone, first, the searcher 24
Thus, in the same manner as in the case of the searcher 51 of FIG. 12, the fingers 21a to 21c are each controlled to demodulate the paths constituting the multipath.

[0082] Incidentally, immediately after the start of operation of the device, the switch SW1 or SW2 is terminal a ₁ or a ₂ side to be selected.

Therefore, in this cellular telephone, as in the cellular telephone of FIG. 12, first, reception and demodulation are performed by the diversity RAKE receiving method.

Thus, the data combiner 22 outputs the combined demodulated data. The combined demodulated data is supplied to the bit detector 13. Bit detector 13
Detects delay information bits (FIG. 2) from the combined demodulated data.

Here, when the cellular telephone is used outdoors, the delay information bit is not inserted into the transmission signal output from the outdoor (base station) antenna.
The bit detector 13 does not detect the delay information bit.

In this case, in the cellular telephone of FIG.
As in the case of the cellular telephone of No. 2, reception and demodulation by the diversity rake reception method are continuously performed as they are.

On the other hand, when the cellular telephone is used indoors where a distributed antenna (FIG. 13) is installed, a delay information bit is inserted into a transmission signal output from the distributed antenna. The bit detection unit 13 detects the delay information bit.

When detecting the delay information bit from the combined demodulated data, the bit detector 13 outputs the delay information bit to the TF 11 and the searcher 24, and
The demodulated data obtained by separating the delay information bits is output to a subsequent processing circuit (not shown).

When the TF 11 receives the delay information bit from the bit detector 13 as described with reference to FIG. 1, the TF 11 sets a coefficient corresponding to the delay time of the multipath represented by the delay information bit in the tap, and The signals of the I and Q channels from 1 and 2 are processed in the same manner as described with reference to FIG. 9 (B), and the signals having the main peak at a predetermined timing and having improved S / N (I and Q channels) (Corresponding to the signals I,
(Referred to as Q channel signal) to terminals b ₁ and b ₂ .

On the other hand, the searcher 24
Upon receiving the delay information bits from the device is recognized as being used indoors, switches respectively switch SW1 or SW2 to a terminal b ₁ or b ₂ side. At the same time, the searcher 24 stops the operation of the fingers 21a and 21b.

As a result, the operating finger 21c
Is supplied with I and Q channel signals having an improved S / N from the TF 11, where the signal processed from the TF 11 is demodulated instead of the path processed according to the control of the searcher 24. Processing is started.

That is, in this case, reception by the RAKE reception method is performed.

Thereafter, in the searcher 24, when the delay information bit from the bit detector 13 is not received for a predetermined time or longer, that is, when the outdoor use of the cellular telephone is started again, the fingers 21a and 21b are turned off. Start operation and switch SW1 or SW
2 causes the terminal a ₁ or a ₂ to be selected. As a result, reception by the diversity rake reception method is performed again.

As described above, when the cellular telephone is used indoors, the three fingers 21a to 21c are used.
The operation of at least one of the fingers 21a and 21b is stopped, so that the power consumed by the device can be saved.

In this embodiment, when the cellular telephone is used indoors, the operation of the fingers 21a and 21b of the three fingers 21a to 21c is stopped, but this operation is stopped. Instead, it can be operated as it is.

In this case, the finger 21c uses RAKE
Since processing according to the reception method is performed, and processing according to the diversity RAKE reception method is performed as a whole, the S / N of the synthesized demodulated data obtained can be further improved.

In this embodiment, the number of fingers is three, but the number is not limited to three.

Further, in the present embodiment, the bit detector 13 detects the delay information bit, and the searcher 24 recognizes whether or not the apparatus is used indoors by using the delay information bit. For example, the searcher 24 can be made to recognize whether or not the apparatus is used indoors as follows.

That is, as shown in FIG. 5, for example, the head of a predetermined frame of a transmission signal is used as a determination bit, and when the transmission signal is output from an outdoor antenna or a distributed antenna, the determination bit is set to 0 or Set each to 1. Then, the bit detection unit 13 detects this determination bit, and uses this determination bit to cause the searcher 24 to recognize whether or not the apparatus is used indoors.

[Fourth Embodiment] Next, a fourth embodiment of the present invention relates to a switch SW provided before the finger 21c.
1 and a switch similar to SW2 and a TF (transversal filter) similar to TF11 are connected to finger 2
The configuration is the same as that of the cellular telephone of FIG. 4 except that it is provided before 1a and 21b.

In this embodiment, when the cellular telephone is used indoors where the distributed antenna is installed, the cellular telephone is arranged at equal intervals as shown in FIG. 6, for example. paths a ₁ to consist of a _3-pass group a, and as with the group of paths a, the path group B consisting of the path b ₁ to b _3, multipath by the path group C consisting of the path c ₁ to c ₃ The transmission signal to be configured is output.

In the cellular telephone, the finger 21
The paths of the path groups A to C are converted into one-pulse signals (signals having one main peak) with improved S / N by the TFs at the preceding stages of a to 21c, respectively, and are demodulated by the fingers 21a to 21c.

In this case, each of the fingers 21a to 21c performs a process according to the RAKE receiving method, and the entire device performs a process according to the diversity RAKE receiving method, thereby minimizing the energy loss of the transmission signal. It becomes possible.

[0104]

According to the first receiving apparatus of the present invention, the delay time information relating to the delay time of the path constituting the multipath is detected from the output of the demodulation means, and the multipath is detected based on the delay time information. Multiply the received signal,
A predetermined coefficient of the product-sum operation means is determined. Therefore, if the delay time of the path does not change, the delay time information needs to be received only once. For example, compared with the case where information for estimating the characteristics of the transmission path such as a sounder is inserted into the transmission signal, Transmission efficiency can be improved.

[0105]

According to the second receiving apparatus of the present invention, the delay time information relating to the delay time of the path is detected from the combined demodulated data obtained by combining the demodulated data output from each of the plurality of demodulation means. , A predetermined coefficient of the product-sum operation means is determined. Then, the search means detects whether or not the apparatus is used indoors. For example, when the apparatus is used indoors, at least one of the plurality of demodulation means is replaced with a product instead of a path. The output of the sum calculating means is demodulated. Therefore, demodulated data (combined demodulated data) having a good S / N ratio can be obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a first embodiment of a cellular telephone to which a receiving device of the present invention is applied.

FIG. 2 is a diagram illustrating delay information bits.

FIG. 3 is a block diagram showing a configuration of a second embodiment of the cellular telephone to which the receiving device of the present invention is applied.

FIG. 4 is a block diagram showing a configuration of a third embodiment of the cellular telephone to which the receiving device of the present invention is applied.

FIG. 5 is a diagram illustrating a determination bit.

FIG. 6 is a diagram illustrating a distribution example of a multipath created by a distributed antenna.

FIG. 7 is a block diagram showing a configuration of an example of a conventional cellular telephone to which the CDMA system is applied.

FIG. 8 is a diagram illustrating multipath.

FIG. 9 is a diagram illustrating a RAKE receiving method.

FIG. 10 is a diagram illustrating a bit error rate when a signal of the DPSK modulation method is received by the RAKE reception method.

FIG. 11 is a block diagram showing a configuration of an example of a conventional cellular telephone to which a RAKE receiving method is applied.

FIG. 12 is a block diagram showing a configuration of an example of a conventional cellular telephone to which a diversity rake receiving method is applied.

FIG. 13 is a diagram illustrating a distributed antenna.

[Explanation of symbols]

 1, 2 Multiplier 3 Voltage Controlled Oscillator 4 Phaser 11 Transversal Filter 12 Demodulation Processor 13 Bit Detector 14 Searcher 15 Transversal Filter 21a to 21c Finger 22 Data Combiner 23 Frequency Error Combiner 24 Searcher 25 Loop Filter 31 Despreader 32 Data demodulation unit 33 Frequency error detection unit 34 Data processing unit 35 Control circuit 41 Matching filter 42 Transversal filter 43 Sounder demodulation circuit 51 Searcher

Claims (3)

(57) [Claims] 1. A multiply-and-accumulate means for multiplying and multiplying a multipath received signal by a predetermined coefficient, a demodulation means for demodulating an output of the multiply-and-sum operation means, and an output of the demodulation means Detecting means for detecting delay time information on a delay time of a path constituting the multipath, wherein the product-sum operation means calculates the predetermined coefficient based on the delay time information detected by the detecting means. A receiving device characterized by determining. 2. A multipath reception signal,
Search means for searching for individual paths; a plurality of demodulation means for demodulating the path searched by the search means and outputting demodulated data; and synthesizing the demodulated data output from each of the plurality of demodulation means, Combining means for outputting combined demodulated data; detecting means for detecting delay time information relating to the delay time of the path from the combined demodulated data output from the combining means; and the delay time information detected by the detecting means. Based on a predetermined coefficient, multiply-accumulate means for multiplying and multiplying the received signal, determiner for determining whether or not the apparatus is used indoors, and based on a determination result of the determiner. The plurality of demodulation means demodulate the path, or at least one of the plurality of demodulation means demodulates the output of the product-sum operation means instead of the path. Receiving device, characterized in that it comprises a control means for controlling Luke. 3. The control means, when the apparatus is used indoors, causes at least one of the plurality of demodulation means to demodulate an output of the product-sum operation means instead of the path. The receiving device according to claim 2 , wherein: