JP2001244861A - Wireless receiving apparatus and method - Google Patents

Abstract

(57) [Problem] To provide a radio receiving apparatus capable of easily and appropriately switching a plurality of antennas and switching a gain and obtaining good communication characteristics even in a fading environment. SOLUTION: In a radio receiving apparatus which performs a diversity reception operation by switching a plurality of antennas 10a and 10b by an antenna selection switch 11a, an antenna which receives this information part before an information part essential for reception in a reception slot is described. Another different antenna is selected, the received signal strength detector 19 measures and stores the received electric field strength, switches to the original antenna, measures the received electric field strength when receiving the information portion, and performs the diversity control and the gain control. 21, comparing the received electric field strength stored previously with the antenna, setting the antenna having the larger received electric field strength as an antenna for receiving an information portion essential for reception of the next slot, and determining the gain state in the next slot by the reception. Set based on the received electric field strength of the antenna with the larger electric field strength.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radio receiving apparatus which performs signal processing based on two orthogonal baseband signals (I and Q signals) to perform detection and demodulation. In addition, the present invention relates to a radio receiving apparatus having a diversity function for switching between two antennas and a gain switching function for preventing saturation of a zero IF (intermediate frequency) signal processing unit and a radio receiving method thereof.

[0002]

2. Description of the Related Art In recent years, as wireless communication devices are applied to mobile communication systems and the like, there is a demand for improved device performance as well as further reduction in size, lower cost, and lower power consumption. Recently, a zero-IF receiver represented by a direct-conversion receiving method has been receiving attention as one of means for realizing miniaturization and low cost of a communication terminal device. In addition, PDC (Personal Digital C)
ellular System), PHS (Personal Handyphone Syst)
In receivers such as em), intermittent reception operation is usually performed to reduce current consumption.

The conventional direct conversion receiver has a problem that the dynamic range cannot be widened because the baseband signal processing section is composed of active elements. To compensate for this, conventionally, the gain of the amplifier is increased. Automatic gain control (AG
C) is being performed.

FIG. 7 is an explanatory diagram showing the timing of a conventional gain switching operation. The received signal strength is detected at preset timings 101 and 102 in the reception slot,
The gain state is determined by comparing whether the detected received signal strength is larger or smaller than a preset value. Then, the determination result of the gain state is reflected at the start of the next reception. This ensures good communication characteristics from a weak electric field to a strong electric field.

[0005] Further, in a mobile station of a mobile communication device, a phenomenon called fading in which the received electric field intensity fluctuates with time as the communication terminal moves appears. Due to the fluctuation of the received electric field strength due to the fading, there is a problem that the communication quality is deteriorated when the received electric field strength is reduced. Conventionally, a technique called diversity has been known as a countermeasure against this fading (see Japanese Patent Application Laid-Open No. 5-206903).
In this diversity, a method of preparing a plurality of antennas and receiving units independent of each other and selecting the antenna having the largest received electric field strength from the outputs of the plurality of antennas and the receiving unit, or a method of adding or combining the respective outputs It is.

In a communication terminal of a mobile communication apparatus, two receiving antennas are prepared and only one receiving unit is provided, and each antenna is switched to measure a receiving electric field strength. An antenna switching reception method for switching to an antenna is often used. This antenna switching reception method has an advantage that it can be realized with a simple configuration.

FIG. 8 is a block diagram showing a configuration for realizing diversity by an antenna switching reception method. Switch 203 selects one of the outputs of antennas 201 and 202 based on a control signal from diversity control section 206. The receiving unit 204 outputs a received signal strength detection signal 207 and an output signal 205 obtained by processing and demodulating the received signal input via the switch 203. Diversity control section 206 switches antennas 201 and 202 based on received electric field strength detection signal 207. At this time, the diversity control unit 206 switches to the first antenna 201 at an arbitrary timing before the information part essential for reception, measures and stores the reception electric field strength, and then switches to the second antenna 202 to switch to the second antenna 202 to receive the reception electric field. The intensity is measured, the measured received electric field strength is compared with the previously stored received electric field strength by the first antenna 201, and control is performed so that the antenna having the larger received electric field strength is used for receiving an information portion essential for reception. I do.

Here, the case of PHS is shown as an example.
FIG. 9 is an explanatory diagram showing a format of a reception slot in the PHS. The reception slot 309 which is a part of the communication slot 300 includes a leading edge guard bit (G) 302, a start symbol (SS) 303, and a preamble (PR).
304, a unique word (UW) 305, an information signal (I) 306, and a trailing edge guard bit (G) 307. The reception slot 309 represents one slot in the communication slot configuration, and the front and rear are a pre-reception slot 301 and a post-reception slot 308. From the viewpoint of ensuring communication quality, it is desirable that the reception after the unique word 305 is performed stably, which is an information part indispensable for reception.
Therefore, it is only necessary to complete the diversity control before the unique word 305.

After the start of the reception slot, reception is performed by the first antenna (310), and the reception electric field strength is measured and stored (31).
3). Subsequently, the reception is switched to the second antenna (31).
1) Measure the received electric field strength (314). Then, the measured received electric field strength of the second antenna and the first stored first
The reception electric field strength of the antenna is compared, the antenna is switched again to the antenna having the higher reception electric field strength (312), and the subsequent slots are received (315). Thus, by configuring the receiving unit to perform the diversity operation,
Good communication quality can be ensured even if fading occurs.

In a wireless communication apparatus, a method of improving communication quality by selecting an antenna having a larger received electric field strength even at the time of transmission is known as transmission diversity (see Japanese Patent Application Laid-Open No. 9-18396). ).

By combining the diversity with the automatic gain control (AGC) described above, it is possible to secure a good communication state in a direct conversion receiver.

[0012]

However, when the antenna is switched for diversity reception, the received signal is disturbed due to this effect. In particular, in a direct conversion type receiver that performs signal processing in the band of a baseband signal, the time constant of the baseband signal processing unit is long, so that the influence is large.

Therefore, when two antennas are switched in a receiving slot, there is a possibility that the disturbance of the received signal does not converge before the information part essential for reception is received. In addition, when the antenna is switched by the diversity, the received electric field strength increases accordingly. Therefore, in the direct conversion receiver, it is necessary to switch the gain in accordance with the antenna switching. this is,
This is because, if the received signal exceeds the dynamic range of the device by switching the antenna, the communication characteristics deteriorate.

Further, when the gain is switched along with the antenna switching due to the diversity, the disturbance of the received signal due to the gain switching is added in addition to the disturbance of the received signal due to the antenna switching, and until the disturbance of the received signal converges. This time may be longer than in the case of only the diversity operation.

On the other hand, the above problem can be solved by preparing two receiving sections corresponding to the two antennas and selecting or synthesizing the outputs, but it is possible to reduce the size and cost. The advantage of the direct conversion receiving method that can be implemented is lost.

As described above, the PH for receiving the TDMA signal
In a conventional radio receiving apparatus using a direct conversion method such as S, it is very difficult to perform antenna switching and gain switching by diversity,
There is a problem that it is difficult to obtain good communication characteristics against fading.

The present invention has been made in view of the above circumstances, and an object of the present invention is to enable easy switching of a plurality of antennas and switching of a gain, and to obtain good communication characteristics even in a fading environment. It is an object of the present invention to provide a wireless receiving apparatus and method capable of performing the above.

[0018]

In order to achieve the above object, a radio receiving apparatus according to the present invention receives an information portion in a reception slot in a radio receiving apparatus which receives a radio signal by switching a plurality of antennas. Previously, selecting means for selecting a second antenna different from the first antenna used for receiving the information portion, and first measuring means for measuring a received electric field strength at the selected second antenna And a second measuring means for measuring a received electric field strength at the first antenna when the information portion in the reception slot is received by the first antenna; and Comparing means for comparing the received electric field strength with the received electric field strength measured by the second antenna; and, based on the result of the comparison, the antenna having the larger received electric field strength is set to the information in the next reception slot. Characterized by comprising an antenna setting means for setting an antenna for use in minute reception.

Preferably, the apparatus further comprises gain control means for controlling the gain when amplifying the received radio signal in accordance with the received electric field strength, wherein the gain control means is based on the set received electric field strength of the antenna. , The gain in the next reception slot is set.

Preferably, a first frequency conversion means for converting the received radio signal into a first intermediate frequency signal, and the first intermediate frequency signal is converted into two orthogonally transformed baseband signals. And a signal processing means for amplifying the baseband signal and limiting the band.

A wireless communication apparatus according to the present invention includes the above-described wireless receiving apparatus in a receiving unit, and further includes a transmitting unit that transmits a wireless signal, wherein the transmitting unit transmits a wireless signal when transmitting the wireless signal.
The antenna set to be used in the immediately preceding reception by the receiving unit is used.

A radio reception method according to the present invention is a radio reception method for receiving a radio signal by switching a plurality of antennas, wherein a radio signal used for receiving the information portion before receiving the information portion in a reception slot. A selecting step of selecting a second antenna different from the first antenna; a first measuring step of measuring a received electric field strength at the selected second antenna; A second measurement step of measuring a reception electric field strength at the first antenna when receiving the signal with the first antenna; and a reception electric field strength measured at the first antenna and measuring the reception electric field strength at the second antenna. A comparison step of comparing the received electric field strength with the received electric field strength, and based on the comparison result, an antenna used for receiving the information portion in the next reception slot using the antenna having the larger received electric field strength. And having an antenna setting step of setting a.

According to the present invention, before receiving the information portion in the current reception slot, a second antenna different from the first antenna used for receiving the information portion is selected, and the selected second antenna is selected. Measure the received electric field strength with the antenna. When the information portion in the current reception slot is received by the first antenna, the reception field strength is measured by the first antenna, and the reception field strength measured by the first antenna and the second antenna Is compared with the reception electric field strength measured in step (1). From the result of this comparison, the antenna with the stronger received electric field strength is set as the antenna used for receiving the information portion in the next reception slot. Further, the gain control means sets the gain in the next reception slot based on the set reception electric field strength of the antenna.

[0024] This makes it possible to easily and appropriately switch a plurality of antennas and to switch gains, and to obtain good communication characteristics even in a fading environment with a small and inexpensive configuration.

Further, in the transmitting means, when the radio signal is transmitted, by using the antenna set to be used in the immediately preceding reception, it is possible to set an optimum antenna in advance at the time of transmission. By combining with the transmission means, a wireless communication device that can obtain good communication characteristics at the time of transmission as well as at the time of reception is realized.

[0026]

Embodiments of the present invention will be described below with reference to the drawings.

The radio receiving apparatus according to the present embodiment uses TDMA
(Time division multiple access) It is preferable to apply the present invention to a mobile communication device (terminal such as a mobile station) that performs intermittent transmission / reception of signals. Here, a configuration example of a TDMA-type mobile communication device is shown.

FIG. 1 is a circuit diagram showing a configuration of a mobile communication device according to an embodiment of the present invention. The mobile communication device includes a wireless signal transmitting / receiving unit 11, a receiving unit 60, and a transmitting unit 30.
Is configured. The receiving unit 60 mainly includes a high-frequency analog signal processing unit 12, a first local oscillation unit 13, a first intermediate frequency signal processing unit 14, a second local oscillation unit 15, a second intermediate frequency signal processing unit 16, Third intermediate frequency signal processing section 17, third local oscillation section 18, received signal strength detection section 1
9, a detection unit 20, a diversity and gain control unit 21, and a DC offset voltage adjustment control unit 25.

The radio signal transmitting / receiving section 11 includes an antenna 10
a, 10b, antenna selection switch 11a, filter 1
1b, an antenna output switch 11c, a radio signal received by one of the antennas 10a, 10b is selected by an antenna selection switch 11a (selection means), and unnecessary frequency components are removed by a filter 11b. The signal is output to the high-frequency analog signal processing unit 12 (first frequency conversion unit) via the antenna output switch 11c.

The high-frequency analog signal processing unit 12 includes a high-frequency amplifier 12a, a high-frequency mixer 12b, a power switch 12
c, the signal output from the radio signal transmitting and receiving unit 11 is amplified by the high frequency amplifier 12a, and then mixed with the local oscillation signal of the first local oscillation unit 13 by the high frequency mixer 12b to obtain the first intermediate frequency. Convert to a signal.

The first intermediate frequency signal processing section 14 (second frequency conversion means) includes a buffer amplifier section 14a having a gain switching function and a quadrature mixer 14b, and converts the first intermediate frequency signal into quadrature signals. The converted I and Q baseband signals are converted. The first intermediate frequency signal processing unit 14 operates upon receiving a local oscillation signal output from a second local oscillation unit 15 that outputs a pair of orthogonal local oscillation signals subjected to orthogonal transformation. The second local oscillator 15
An oscillator 15a and a 90-degree phase shifter 15b,
A pair of local oscillation signals having the same frequency as that of the first intermediate frequency signal and being out of phase with each other by 90 degrees are output.

Here, the first intermediate frequency signal processing section 14
Output signal contains a DC offset voltage that hinders signal processing. This is caused by self-mixing due to the local oscillation signal leaking into the input side of the first intermediate frequency signal in the quadrature mixer 14b, and by element mismatching, and is well known in a direct conversion receiver. It is a phenomenon that was done. The DC offset voltage is controlled by a DC offset voltage adjustment control unit 25, a first DC offset voltage adjustment unit 26, a subtracter 26a, a second DC offset voltage adjustment unit 27, and a subtractor 27a.
Rough adjustment of the DC offset voltage is performed (hereafter,
This operation is called coarse adjustment). Details of the coarse adjustment operation will be described later.

The second intermediate frequency signal processing section 16 (signal processing means) includes first baseband amplifiers 16a and 16d whose gain can be set, low-pass filters 16b and 16
e, and the second baseband amplifiers 16c and 16f. After the adjustment of the DC offset voltage, the I and Q baseband signals are amplified to a required level by the second intermediate frequency signal processing unit 16, and the band is limited so that only the necessary signal components are provided. Is taken out.

Further, the second intermediate frequency signal processing section 16
DC offset voltage adjustment controller 2 for the output signal of
5. Third DC offset voltage adjusting unit 28, subtractor 28
a, fourth DC offset voltage adjusting unit 29 and subtractor 2
9a, fine adjustment of the DC offset voltage is performed. As a result, the deterioration of the receiving characteristic due to the DC offset voltage is suppressed to an allowable value (hereinafter, this operation is referred to as fine adjustment). The details of the fine adjustment operation will be described later together with the details of the coarse adjustment operation.

The third intermediate frequency signal processing section 17 includes a quadrature modulator 17a, a band pass filter 17b, and a limiter amplifier 17c. The I and Q baseband signals whose DC offset voltage has been adjusted are output to the quadrature modulator 17.
a and the third local oscillator 18 converts the frequency into a third intermediate frequency signal, and the bandpass filter 17b removes unnecessary frequency components mainly including harmonic components generated by the frequency conversion. The signal is amplified by 17c, and its amplitude is limited. The third local oscillator 18 includes an oscillator 18a, a frequency divider 18b, and a phase shifter 18c.
And outputs a pair of orthogonal local oscillation signals subjected to orthogonal modulation. Then, the output signal of the limiter amplifier 17c is input to the detector 20 and detected and demodulated.

The received signal strength detecting section 19 (first measuring means, second measuring means) includes the first received signal strength detecting section 1.
9a and a second received signal strength detector 19b. The reception signal strength detection section 19 is connected to the limiter amplifier 17c and outputs a voltage proportional to the reception signal strength. The first received signal strength detection section 19a is connected to the detection section 20, and its output signal is used as information such as a received field strength display. On the other hand, the second received signal strength detection unit 19b is connected to a diversity control and gain control unit 21 (comparison unit, antenna setting unit, gain control unit) that performs diversity and gain switching control, and the output signal is It is used as information when performing diversity control and gain switching control.

As described above, in the receiving section 60 of the present embodiment, like the conventional superheterodyne receiver, the limiting signal whose amplitude is limited is output from the limiter amplifier 17c. A detector similar to a superheterodyne receiver can be effectively used as the demodulator 20 for demodulation.

Next, the adjustment operation (coarse adjustment, fine adjustment) of the offset voltage by the first to fourth DC offset voltage adjustment units 26, 27, 28, 29 will be described. FIG. 2 shows FIG.
3 is a circuit diagram showing a configuration of a DC offset voltage adjustment control unit 25 in FIG.

The quadrature modulator 17a includes mixers 17d and 17d.
e, and these mixers 17d and 17e include:
A pair of orthogonal local oscillation signals 18d and 18e are input from the third local oscillation unit 18, respectively. Then, a quadrature modulation output signal 17f is output from the quadrature modulator 17a.

The DC offset voltage appearing on the input side of the mixer 17d has the same frequency as the local oscillation signal 18d of the third local oscillator 18 and the phase substantially equal to the phase of the local oscillation signal 18d at the output side of the mixer 17d. Has,
The amplitude appears on the input side of the mixer 17d as a signal proportional to the DC offset voltage (hereinafter, referred to as a carrier leak signal). This carrier leak signal is obtained by mixing a DC offset voltage having a frequency of 0 Hz with a local oscillation signal having a third local oscillation frequency and converting it into a third local oscillation frequency ± 0 Hz, that is, a frequency equal to the third local oscillation frequency. It is caused by being done.

The DC offset voltage adjustment controller 25 includes:
A quadrature modulation output signal 17f including a carrier leak signal from the quadrature modulator 17a is input. The DC offset voltage appearing on the input side of the mixer 17d is obtained by amplifying the carrier leak signal with an amplifier 25a, and then performing phase detection on the local oscillation signal 18d from the third local oscillation unit 18 with a mixer 25b, and performing low pass. By removing the high frequency component by the filter 25e, it can be detected again as a DC component. Similarly, the DC offset voltage appearing on the input side of the mixer 17e can be detected by switching the switch 25d to the mixer 25c.

Based on the DC offset voltage thus detected, the DC offset voltage adjustment control unit 25k
Determines whether the output value is increased or decreased, or determines whether the DC offset voltage is within an allowable range (hereinafter, this determination operation is referred to as convergence determination). This convergence determination can be performed using two comparison circuits 25i and 25j and two corresponding reference voltages 25f and 25g.

When the DC offset voltage is positive, the detected output signal of the detected DC offset voltage is positive, while when the DC offset voltage is negative, the detected output signal of the detected DC offset voltage is Becomes negative.
By setting the positive reference voltage 25f and the negative reference voltage 25g to be compared with the detection output signal in the comparison circuits 25i and 25j to the allowable upper limit value and the lower limit value of the allowable DC offset voltage, respectively. , It can be determined whether the adjustment value should be increased or decreased, or whether it has converged. The bias voltage 25h is a voltage source to be added when setting the positive reference voltage 25f and the negative reference voltage 25g.

The DC offset voltage adjustment control unit 25k includes:
An operation for increasing or decreasing the value of the DA converter 25L is performed according to the output signals of the comparison circuits 25i and 25j. The output of the DA converter 25L is connected to a subtractor 26a that removes a DC offset voltage, and adjusts the DC offset voltage of the I signal side output of the first intermediate frequency signal processing unit 14. By repeating this operation until the convergence state is determined, the DC offset voltage is adjusted by the first DC offset voltage adjustment unit 26.

By performing the same operation from the second DC offset voltage adjusting unit 27 to the fourth DC offset voltage adjusting unit 29, it is possible to adjust the DC offset voltage existing in the receiver. . Here, at the time of adjustment by the third and fourth DC offset voltage adjustment units 28 and 29, the adjustment accuracy of the DC offset voltage can be further enhanced by narrowing the voltage range of the two reference voltages 25f and 25g.

When a radio signal is input during the adjustment of the DC offset voltage, it acts as noise, and the adjustment accuracy of the DC offset voltage may be degraded. In order to avoid this problem, the wireless signal is cut off by disconnecting the power supply of the high-frequency analog signal processing unit 12 by the power switch 12c or by connecting the antenna output switch 11c of the wireless signal transmitting / receiving unit 11 to the transmitting unit 30 side. can do.

When the gain is switched, the DC offset voltage changes accordingly. For this purpose, each gain state is forcibly switched, and the DC offset voltage is adjusted for each gain state. Is performed, and the adjustment result is stored, and when the gain is switched in the reception state, the adjustment result stored corresponding to the gain state is output to avoid the situation.

Next, the operation of diversity and gain switching will be described. Here, AGC is performed in descending order of the gain of the receiver.
It is assumed that three gain states of a 0 mode, an AGC1 mode, and an AGC2 mode can be selected. FIG. 3 is a table showing the three gain states that have been set.

The AGC0 mode is a state in which the gains of the buffer amplifier 14a and the first baseband amplifiers 16a and 16d are set to the maximum. The AGC1 mode is a state in which only the gains of the first baseband amplifiers 16a and 16d are reduced by 15 dB. In the AGC2 mode, the buffer amplifier 14a
Is reduced by 15 dB, and the gains of the first baseband amplifiers 16a and 16d are reduced by 15 dB. The state of the gain in each mode corresponds to the received electric field strength,
Switching is performed so that the received signal does not exceed the dynamic range of the device.

Further, as shown in FIG. 1, two antennas for diversity are provided, a first antenna 10a and a second antenna 10b, and the antenna is switched by an antenna selection switch 11a. Further, it is assumed that the format of the radio signal is the same as the format of the PHS signal (see FIG. 9) described in the section of "Prior Art".

FIG. 4 shows a diversity control and gain control section 21.
FIG. 4 is an explanatory diagram showing operation timings in FIG. here,
The antenna determined to have a large received electric field strength in the (n-1) -th slot is represented by ANT (n), the other antenna is represented by / ANT (n), and the gain state corresponding to ANT (n) is represented by AGC (ANT ( n)).

In the n-th reception slot 31, before the start of the reception slot, the gain state is changed to AGC (ANT).
(n)) is set (32), and thereafter, reception is performed with the gain fixed until the n-th reception slot ends. Before the start of the reception slot, the antenna is switched to / ANT (n) (33). Then, before the unique word UW in the reception slot, the reception electric field strength at the antenna / ANT (n) is measured (34), and the reception electric field strength is stored (35). Subsequently, the antenna is switched to the antenna ANT (n) (36). The antenna switching timing is set before the unique word UW, and the disturbance of the received signal due to the antenna switching converges before the unique word UW.

After switching to antenna ANT (n), n
Antenna ANT (n) until the reception slot ends
(36). Here, the reception electric field strength is measured during reception by the antenna ANT (n) (37). The measurement timing may be any timing. However, in order to obtain a stable detection result in the received signal strength detection unit 19, it is preferable that the data pattern be in a unique word UW having a fixed data pattern.

Then, the reception electric field strength at the antenna ANT (n) and the antenna / ANT measured and stored previously
By comparing the received electric field strength in (n), the antenna having the higher received electric field strength level is determined, and the antenna is set as the antenna ANT (n + 1) (38). Further, based on the received electric field strength of the antenna having the higher received electric field strength level, a gain state corresponding to the received electric field strength is determined, and the gain state AGC (ANT (n + 1)) 41 of the (n + 1) th receiving slot 40 is set. (39).

The operation in the (n + 1) th reception slot and thereafter is the same as the operation in the nth reception slot.
Here, when n = 1, there is no information of the previous slot, and in this case, the antenna ANT (0) and the gain AGC (ANT (0))
Can be arbitrarily selected. As described above, even if the antenna and the gain are arbitrarily selected, the inconvenience occurs only in the slot of n = 1, and there is no problem in the overall communication characteristics.

FIG. 5 is an explanatory diagram showing the operation timing during a reception slot more specifically. Where n-1
In the third reception slot, it is assumed that the gain state is the AGC1 mode state. Further, based on the comparison result of the reception electric field strengths of the two antennas of the first antenna 10a and the second antenna 10b, the reception electric field strength of the second antenna 10b is large (ANT (n) = the second antenna ). Further, the received electric field strength of the second antenna is lower than the gain state in the AGC1 mode, that is, the AGC
It is assumed that it is determined that the camera is in the two-mode state (AGC (ANT (n)) = AGC2) (42).

In the n-th reception slot, first, before the start of the reception slot, the gain state is switched to the AGC2 mode (43). Thereafter, the reception is fixed in the AGC2 mode until the n-th reception slot ends. Further, before the start of the reception slot, switching to the first antenna (4)
4). Before the unique word UW in the reception slot, the reception electric field strength at the first antenna is measured (45),
The received electric field strength is stored (46). Subsequently, switching to the second antenna is performed (47). After switching to the second antenna, reception is performed by the second antenna until the n-th reception slot ends.

Here, the reception electric field strength is measured during reception by the second antenna (48). The received electric field intensity at the second antenna is compared with the received electric field intensity at the first antenna measured and stored in advance, and the antenna having the higher received electric field intensity level is determined (49). Further, a gain state corresponding to the received electric field strength of the antenna having the higher received electric field strength level is determined (50). Thereafter, the operation in the (n + 1) th reception slot is the same as the operation in the nth reception slot.

The above-described diversity control and gain control can be applied when synchronization with the reception slot timing is established. However, for example, when synchronization with the reception slot timing is not taken, such as at power-on, the output signal from the diversity control and gain control unit 21 is fixed so as not to switch the antenna, For switching the gain, for example, as shown in FIG. 6, the gain state is determined at the start of the reception slot (5
1) The control may be performed such that the gain is immediately switched (52). FIG. 6 is an explanatory diagram showing the operation timing of gain switching at the time of power-on or the like.

As described above, according to the present embodiment, the switching of the antenna and the switching of the gain by the diversity can be easily and appropriately performed, and a good communication characteristic can be obtained even in a fading environment with a small and inexpensive configuration. Can be. In this case, the gain state is constant in each reception slot, and the antenna is switched only once by diversity in the slot, so that signal disturbance in the slot can be minimized, and Indispensable information portions can be received stably.

The present invention is not limited to the configuration of the embodiment described above, but may be applied to any configuration within the scope described in the claims, and the configuration may be modified in various ways. It is possible.

For example, a configuration in which the radio signal received by the high-frequency analog signal processing unit 12 is once converted into a first intermediate frequency signal and then converted into a baseband signal has been described as an example. The present invention is similarly applicable to a receiver configured to directly convert to a baseband signal without performing conversion.

The configuration of the radio signal transmitting / receiving section 11 is not limited to the configuration shown in FIG. 1 as long as a plurality of antennas can be switched as appropriate. For example, three or more antennas can be provided and switched individually,
Alternatively, the antennas may be switched so that radio signals from a plurality of antennas are combined.

Further, the second intermediate frequency processing section 16 and subsequent sections can be similarly applied to a digital signal processing using an AD converter.

Since the antenna determined and selected by the diversity receiving unit 60 is known to be effective in improving the communication characteristics at the time of transmission, it is used for transmission of radio signals as transmission diversity. As for the antenna, the receiving unit 60 may be configured to select the antenna used for the immediately preceding reception.

As described above, in the present embodiment, when performing reception over a plurality of slots with a receiver of a direct conversion system such as an intermittent reception operation in a TDMA system, switching of a plurality of antennas by diversity and A
The gain switching of the GC can be easily and appropriately performed. Therefore, with a small and inexpensive configuration, it is possible to obtain good communication characteristics even in a fading environment. In addition, it is possible to estimate an optimal antenna at the time of transmission, and to realize a wireless communication device capable of obtaining good communication characteristics even at the time of transmission by combining the reception unit and the transmission unit.

[0067]

As described above, according to the present invention, the switching of a plurality of antennas and the switching of the gain can be easily performed, and an excellent communication characteristic can be obtained even in a fading environment. can get.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a configuration of a mobile communication device according to an embodiment of the present invention.

FIG. 2 is a circuit diagram showing a configuration of a DC offset voltage adjustment control unit in FIG.

FIG. 3 is a table showing three gain states that have been set;

FIG. 4 is an explanatory diagram showing operation timing in a diversity control and gain control unit.

FIG. 5 is an explanatory diagram showing operation timing during a reception slot more specifically;

FIG. 6 is an explanatory diagram showing an operation timing of gain switching when synchronization with a reception slot timing such as when power is turned on is not achieved;

FIG. 7 is an explanatory diagram showing the timing of a conventional gain switching operation.

FIG. 8 is a block diagram showing a configuration for realizing diversity by an antenna switching reception method.

FIG. 9 is an explanatory diagram showing a format of a reception slot in the PHS.

[Explanation of symbols]

 10a first antenna 10b second antenna 11 radio signal transmitting / receiving section 11a antenna selection switch 14 first intermediate frequency signal processing section 14a buffer amplification section 16 second intermediate frequency signal processing section 16a, 16d first baseband amplifier 19 reception Signal strength detection unit 21 Diversity control and gain control unit 25 DC offset voltage adjustment control unit

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Takashi Ui 4-3-1 Tsunashima Higashi, Kohoku-ku, Yokohama, Kanagawa Prefecture Inside Matsushita Communication Industrial Co., Ltd. No.3-1, Matsushita Communication Industrial Co., Ltd. F-term (reference) 5K059 CC02 CC03 DD02 DD27 DD44 EE02 5K061 AA11 BB12 CC02 CC05 CC46 CC52 CD01 FF17

Claims (5)

[Claims] 1. A radio receiving apparatus for receiving a radio signal by switching a plurality of antennas, wherein before receiving an information portion in a reception slot, a second antenna different from the first antenna used for receiving the information portion is provided. Selecting means for selecting an antenna, first measuring means for measuring a received electric field strength at the selected second antenna, and when an information portion in the receiving slot is received by the first antenna. Second measuring means for measuring the received electric field intensity at the first antenna, and comparing the received electric field intensity measured at the first antenna with the received electric field intensity measured at the second antenna. Comparing means, based on the comparison result, an antenna setting means for setting an antenna having a larger received electric field strength as an antenna used for receiving an information portion in a next reception slot. Radio receiving apparatus, characterized in that. 2. A gain control means for controlling a gain when amplifying a received radio signal in accordance with a received electric field strength, wherein the gain control means determines a next time based on the set received electric field strength of the antenna. 2. The radio receiving apparatus according to claim 1, wherein said gain in a receiving slot is set. 3. A first frequency converting means for converting a received radio signal into a first intermediate frequency signal, and a second frequency converting means for converting the first intermediate frequency signal into two orthogonally transformed baseband signals. The radio receiving apparatus according to claim 1, further comprising: a frequency conversion unit configured to amplify the baseband signal and a signal processing unit configured to limit a band of the baseband signal. 4. The radio receiving apparatus according to claim 1, further comprising: a transmitting unit that transmits a radio signal, wherein the transmitting unit transmits a radio signal when the radio unit transmits immediately before the radio signal is received by the receiving unit. A wireless communication device using an antenna whose use has been set. 5. A radio receiving method for receiving a radio signal by switching a plurality of antennas, wherein said method is different from a first antenna used for receiving said information portion before receiving an information portion in a reception slot. A selecting step of selecting a second antenna; a first measuring step of measuring a reception electric field strength at the selected second antenna; and receiving the information portion in the reception slot by the first antenna. A second measuring step of measuring a received electric field strength at the first antenna; and a receiving electric field strength measured at the first antenna and a received electric field strength measured at the second antenna. A comparing step of comparing, based on the result of the comparison, an antenna that sets the antenna having the larger received electric field strength as the antenna used for receiving the information portion in the next reception slot. Radio receiving method characterized by having a constant step.