JPH06291704A - Diversity device - Google Patents

Abstract

PURPOSE:To obtain high diversity gain and to suppress the intrusion of switching noise by controlling an antenna group switching means so as to switch to an antenna group including branches where reception signal quality is the highest. CONSTITUTION:The radio waves received by antennae 10a and 10b are amplified by low noise amplifiers 11a and 11b and the output is connected with terminals 13a and 13b or terminals 14a and 14b by changeover switches 12a and 12b. The terminals 13a and 13b are the direct paths of antenna output, and the terminals 14a and 14b are the paths outputting the synthetic outputs of two antennae by making them have a phase difference by a 90 deg. hybrid 15. The outputs become two system output by 90 deg. hybrid 16a and 16b, and a frequency conversion is performed for the antenna group switching output by frequency converters 20a and 20b. Subsequently, amplitude is adjusted by automatic gain adjusters 21a and 21b and it is inputted in a control circuit 23. The control circuit 23 controls antenna group changeover switches 12a and 12b so that signal quality may be the highest.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a signal transmitting / receiving apparatus in wireless communication, and more particularly to a diversity apparatus.

[0002]

2. Description of the Related Art In diversity, the influence of multipath can be reduced by increasing the number of antennas. In space diversity, multiple antennas are installed at a distance. Each antenna system must be sufficiently uncorrelated. For that purpose, it is desirable that the antennas are separated by a quarter wavelength or more. Therefore, when considering a small mobile terminal, only about two antennas can be installed.

Looking at the prior art, for example, JP-A-60-13
In the 5024 publication, a phase change circuit that changes the phase of the signal from the antenna is provided between the antenna and the receiver, and the directional pattern of the antenna is changed by changing the phase and combining, and the number of antennas does not increase. Describes a diversity receiver that increases the antenna pattern.

Regarding a technique for performing directional diversity by using a non-directional antenna as a directional antenna by an array, for example, Japanese Unexamined Patent Publication No. Sho 58-69140 is provided with a diversity antenna using four dipole antennas. Receivers are listed.

[0005]

In the above-mentioned prior art, since switching is performed in the high frequency section before detection, there is a discontinuity in amplitude or phase before and after switching. Therefore, switching noise is added to the signal component. In particular, when receiving in a weak electric field area, switching is frequently caused by noise in the high-frequency amplification section because of the low S / N ratio.

When considering indoor use, the terminal does not move at high speed. The change in the radio environment is slow, and the state where the received electric field is weak continues for a long time. As a result, burst errors are likely to occur.

The effects differ between directional diversity and space diversity depending on the arrival environment of radio waves. That is, in an environment in which one strong direct wave arrives, the reception electric field is at the same level in space diversity, and switching is likely to occur frequently. At this time, the received signal power from the antenna can be larger in the directional diversity in which the directional gain of the antenna can be earned. On the other hand, in an environment where a standing wave with a very large standing wave ratio stands, the radio waves coming from the left and right are almost at the same level, and switching is likely to occur frequently in directional diversity. At this time, in the antinode of the standing wave, the electric field strength is increased by 3 dB due to the combination of the radio waves coming from the left and right, and the space diversity which receives this is advantageous.

When performing diversity reception in a portable radio terminal, it is general to equip a pull-out antenna as a main antenna and a built-in antenna as an auxiliary antenna. In this way, different types of antennas have different antenna gains, and thus it is not possible to obtain directivity with low correlation between the two simply by shifting the phase as in the prior art.

In view of the problems of the prior art, one object of the present invention is to combine two antenna outputs through a phase shifter to obtain two combined outputs having the effect of directional diversity. Is added to the antenna output, that is, two space diversity outputs to achieve 4-branch diversity and enhance the diversity effect.

Still another object of the present invention is to divide four diversity branches into two groups, that is, a group of directional diversity branches (a group of directional diversity antennas) and a group of space diversity branches (a group of space diversity antennas). By comparing the sets and selecting and switching the set with higher diversity effect in the high frequency section, the circuit scale of the demodulator etc. can be reduced,
It is to reduce the price of the diversity device.

Still another object of the present invention is to reduce the power consumption of the diversity device by reducing the circuit scale of the demodulator and the like.

Still another object of the present invention is to reduce the switching noise generated at the time of pre-detection switching by selecting the directional diversity antenna group and the space diversity antenna group with a burst of a certain length.

Still another object of the present invention is to prevent characteristic deterioration due to burst switching by performing selective switching of the branches in the antenna group even when the reception level of the currently selected branch is instantaneously lowered. , To compensate for good communication.

Still another object of the present invention is to prevent switching noise and perform good communication by performing branch switching within the selected antenna group after detection.

Still another object of the present invention is to adjust the level of a signal from an antenna so that directivity can be obtained even with antennas having different gains.

Still another object of the present invention is to select an antenna group having a large diversity effect in advance even when the branch switching within the selected antenna group is performed before detection, so that the antenna group is selected. The average received electric field level difference of each branch is large, the probability of branch switching within the set is suppressed small, and the mixing of switching noise is suppressed low.

Still another object of the present invention is to use the same antenna system as the receiving antenna even at the time of transmitting a radio wave so that the radio wave can be transmitted more effectively, the frequency can be effectively used, and the transmission power can be reduced. To do.

[0018]

Means for Solving the Problems The above problems include a plurality of antennas placed apart from each other, a combining means for combining the output of each antenna with at least one other antenna output through a phase shifter, and each antenna output. An antenna group switching means for selecting whether to output through the combining means or to directly output each antenna output, and a receiver for detecting the received signal quality of each output from the antenna group switching means and performing diversity reception, Accumulating means for accumulating the received signal quality detected by the receiver before the antenna group switching means switches the antenna group, and the received signal quality before the antenna group switching accumulated in the accumulating means and the antenna group output by the detecting means The received signal quality after switching is compared every predetermined period and switched to the antenna group including the branch with the highest received signal quality. Is solved by having a control means for controlling so that antenna group switching means.

In the solution means, the receiver detects a plurality of demodulators for demodulating each output from the antenna group switching means, a detecting means for detecting the received signal quality from each demodulator output, and the detecting means. The problem can be solved by using branch switching means for selecting the demodulator output that is the best in the received signal quality.

Further, in the solving means, the plurality of outputs of the antenna group switching means are switched after detection by the demodulator, the detecting means and the branch switching means, but the signal quality of each output of the antenna group switching means is detected. The detection means, the branch switching means for selecting the best branch from the signal quality detected by the detection means, and the demodulator for demodulating the signal of the branch selected by the branch switching means may cause a problem even if the pre-detection switching is performed. Can be resolved.

Further, when the communication is performed by the time division multiple access (TDMA) system, the problem is solved by switching the antenna group of the antenna group switching means outside the communication burst.

Further, in the case of performing communication by the time division multiple access system, the problem can be solved by forcibly switching the antenna group switching means in the fixed rear part of the used burst.

Further, as means for detecting the quality of the received signal, an averaging means for taking out the received signal level from the receiver and taking a time average for a certain period is provided, and the accumulating means is the output of the averaging means before switching the antenna group. The signal level is stored in advance, and the average reception signal level before switching the antenna group stored in the storage means by the control means is compared with the average signal level output by the averaging means after switching the antenna group, and the average reception level is better. The problem is solved by controlling the antenna group switching means so as to be large.

As a means for detecting the quality of the received signal, an arithmetic means for extracting the received signal level from the receiver and taking the ratio of the two having the maximum level among them, and the time in a certain period of the ratio obtained by the arithmetic means An average means for obtaining an average is provided, and the average reception signal level ratio which is the output of the averaging means before the antenna group is switched is stored in the storage means, and the average reception before the switching of the antenna group is stored in the storage means by the control means. The problem is solved by comparing the level ratio and the average received signal level ratio after switching the antenna group output by the averaging means, and controlling the antenna group switching means so that the ratio becomes large.

As means for detecting the received signal quality, the receiving signal level is taken out from the receiver and the difference between the two having the maximum level is calculated, and the time in a certain period of the difference obtained by the calculating means. An average means for obtaining an average is provided, and the storage means stores the received signal level difference output from the averaging means before switching the antenna group, and the control means stores the average received signal before switching the antenna group. The problem is solved by comparing the level difference and the average signal level difference after switching the antenna group output by the averaging means, and controlling the antenna group switching means so that the difference becomes larger.

Further, in order to improve the situation where the antenna group switching means does not switch continuously, in addition to the control means, the number of times the control means does not instruct the antenna group switching means to switch continuously is counted. The problem can be solved by providing the counting means for performing the counting and the interrupting means for forcibly instructing the antenna group switching means to switch the antenna group when the counting means counts a fixed number.

Further, if the interrupting means is provided with a function of changing the count upper limit of the counting means according to the reception state, the problem can be solved.

In the solving means, the antenna output is combined with the other antenna output through the phase shifter in the combining means. However, when the antenna gain is different, the attenuator and the attenuator and the phase shifter are included in the combining means. The problem can be solved by adding an amplifier and adjusting the received electric field level to the same level in advance.

Further, when the antenna gain is different in the solving means, a low noise amplifier is provided between each antenna and the antenna group switching means, and the amplification degree of the low noise amplifier is adjusted in advance, and then the antenna group switching means. The problem can be solved even if the gains of the respective inputs are matched.

Further, the above-mentioned problem is that a plurality of antennas placed apart from each other, combining means for combining the antenna output with at least one other antenna output through a phase shifter, and each antenna output through the combining means. Antenna group switching means for selecting whether to directly output each antenna output, a receiver for receiving each output from the antenna group switching means with maximum ratio combining diversity, and a receiver output with maximum ratio combining Detection means for detecting the signal quality of the signal output, storage means for storing the signal quality detected before the antenna group is switched by the antenna group switching means, and signal quality before the antenna group switching stored in the storage means And the signal quality after switching the antenna group output by the detection means are compared in a predetermined cycle so that the signal quality becomes highest. Also it can be solved by having a control means for controlling the Rikae means.

Further, at the time of transmission, the problem can be solved by transmitting radio waves through the same antenna system as the branch selected at the time of reception.

[0032]

In the above solving means, a plurality of antennas placed apart from each other, combining means for combining the antenna output with at least one other antenna output through the phase shifter, and output of each antenna output through the combining means. Antenna group switching means for selecting whether to directly output each antenna output. The direct output group from the antenna acts as a space diversity antenna because the antennas are placed at different positions. On the other hand, the output group combined by the combining means becomes the output group of the directional antenna,
Acts as a directional diversity antenna.

The effects of directional diversity and space diversity differ depending on the arrival environment of radio waves. Diversity gain can be improved by grasping the incoming radio wave environment and receiving with a more effective antenna group. In particular, in a portable wireless terminal whose main place of use is indoors, the terminal itself does not move at high speed. Therefore, it is sufficient that the switching cycle of the antenna group switching means is longer than the symbol rate.

The symbol rate represents the speed of a received code (symbol), and is the number of codes transmitted within a unit time. Therefore, a time counting means for counting the number of received symbols is provided, and a trigger signal is sent to the control means every certain fixed period (every fixed symbol reception). The control means receiving the trigger signal compares the signal quality before switching the antenna group with the signal quality after switching the antenna group, and switches the antenna group switching means to the one having better characteristics. Here, the signal quality before switching is the signal quality detected by the detecting means at the time of the previous switching is stored in the storing means. By this switching, an antenna group having a high diversity effect is selected, and a high diversity gain can be obtained by performing diversity reception on the selected antenna group. Moreover, since switching in the high-frequency section is performed at regular intervals, mixing of switching noise is suppressed, and the problem is solved by the present invention.

The antenna group is selected at high frequency,
The number of parts of the mixer, LPF and demodulator can be halved, the device price can be reduced, and the power consumption can be reduced. Therefore, the problem is solved by the present invention.

In this solving means, if a plurality of outputs of the antenna group switching means are demodulated by the demodulator, the detecting means, and the branch switching means and the switching diversity is carried out after detection, even when the propagation situation suddenly changes, It is possible to prevent a sharp deterioration in reception quality without switching noise. Therefore, the problem is solved by the present invention.

In this solving means, the plurality of outputs of the antenna group switching means are switched after detection by the demodulator, the detecting means and the branch switching means. However, the detecting means for detecting the signal quality of each output of the antenna group switching means. Also, the pre-detection switching can be performed by the branch switching unit that selects the best branch from the signal quality detected by the detection unit and the demodulator that demodulates the signal of the branch selected by the branch switching unit. In this case, since the antenna group switching means has previously selected an antenna group having a high diversity effect and the branch switching means performs switching less frequently, the probability that noise due to switching is mixed is reduced.
Therefore, the problem is solved by the present invention.

The division multiple access method is a method in which the same channel is used by a plurality of terminals in a time division manner. Communication bursts for communication are roughly classified into a preamble and a data burst. The preamble consists of a unique word for synchronizing communication bursts, carrier recovery for symbol synchronization, and line control information. In this time division multiple access method, since another terminal is communicating with the base station, there is an idle time during which communication is not performed.
Therefore, if the antenna groups are switched during this idle time, noise due to switching can be avoided. That is, if the length of the communication burst and the cycle of switching are matched in the above solving means, switching of the antenna group can be performed without any switching noise. Therefore, the problem is solved by the present invention.

In the pre-solution means, the signal quality stored in the storage means before the switching of the antenna groups starts to deviate from the actual value when the switching of the antenna groups does not occur continuously. Therefore, more accurate switching can be performed by updating the value accumulated at a certain time. In the case of time division multiple access, it is the miss of unique word detection in the preamble that has the greatest effect on bit errors. In order to prevent this error as much as possible and to periodically detect the signal quality of the currently unconnected antenna group, the reception of the last fixed number of symbols in the used data burst is forcibly switched and received. To do.

Thus, the detection of the unique word is received by the antenna group having a high diversity gain, and the received signal quality of the non-selected antenna group is also updated for each burst. In this case, switching noise is generated during forced switching,
The switching frequency can be kept constant. Further, although it means that an unfavorable antenna group is selected by the compulsory switching, diversity reception is performed in the antenna group, which does not lead to a sudden deterioration of the error rate. Therefore, the problem is solved by the present invention.

As means for detecting the quality of the received signal, there is provided an averaging means for taking out the received signal level from the receiver and taking a certain period of time. The averaged received signal level after switching the antenna group, which is the output of the averaging means, and the accumulating means. If the control means for comparing the average received signal level before switching the antenna group stored in the above and controlling the antenna group switching means so that the average received level becomes larger, the selected antenna group has It is a group including the largest branch, and in the neighborhood time, the probability that the branch is the largest is high. This is because the fading frequency is low when used indoors. Therefore, the problem is solved by the present invention.

As means for detecting the quality of the received signal,
It is provided with an arithmetic means for taking two of the maximum received signal levels from the receiver and for obtaining the ratio thereof, and an averaging means for averaging the arithmetic outputs over a fixed period of time. By providing a control means for controlling the antenna group switching means so as to select an antenna group having a large ratio by comparing the average received signal level ratio with the average signal level ratio stored in the storage means before switching the antenna group,
Since the selected antenna group is an antenna group having a higher diversity effect, the frequency of branch switching within the antenna group decreases. Therefore, the problem is solved by the present invention.

As means for detecting the quality of the received signal,
An antenna having a large difference between the average signal level differences, which is provided with an arithmetic means for taking two of the maximum received signal levels from the receiver and obtaining the difference between them and an averaging means for averaging the arithmetic outputs over a certain period of time. By providing the control means for controlling the antenna group switching means so as to select a group, the frequency of branch switching in the antenna group is reduced because the selected antenna group is a group having a higher diversity effect. Therefore, the problem is solved by the present invention.

In the present invention, the signal quality stored in the storage means before the switching of the antenna groups starts to deviate from the actual value when the switching does not occur continuously. Therefore, more accurate switching can be performed by updating the value stored in the storage means at a certain time. In addition to this control means, a counting means for counting the number of times that the control means does not instruct the antenna group switching means to switch continuously,
When the counting means counts a certain number of times, an interrupting means for forcibly instructing the switching to the antenna group switching means is provided to prevent the same antenna group from being continuously selected for a certain period or longer. As a result, switching can be performed by appropriate determination, and the quality of the received signal is improved, so that the problem is solved by the present invention.

Further, by providing the interrupting means with a function of changing the count upper limit of the counting means according to the receiving state, it is possible to follow the change of the propagation state and to control the switching means by more appropriate judgment. it can. Therefore, the problem can be solved by the present invention.

When this effect is obtained by the antennas having different antenna gains, the level of the received signal, which is the antenna output with respect to the received electric field strength, is different. Therefore, the level is adjusted by the attenuator and the amplifier in addition to the phase shifter. As a result, the combined output can have the same directivity as when an antenna with the same gain is used. Therefore, the problem can be solved by the present invention.

When the antenna gains are different, if the gain of the low noise amplifier provided between the antenna and the antenna group switching is adjusted in advance, the received signal levels can be matched and the combined outputs have the same gain. It is possible to give the same directivity as when an antenna is used. Therefore, the problem can be solved by the present invention.

If the maximum ratio combining diversity receiver is used as the receiver and the detecting means for detecting the received signal quality is provided, the antenna group switching means can be controlled so as to select the antenna group having a higher diversity gain. Therefore,
The problem is solved by the present invention.

If the antenna group switching circuit is a bidirectional circuit and a transmitter for transmitting radio waves from the same antenna branch with reference to the branch selection output of the receiver is provided, it is most likely to communicate with the other party performing wireless communication. Radio waves will be transmitted with suitable directivity. Therefore, the problem is solved by the present invention.

[0050]

Example 1 Example 1 of the diversity apparatus of the present invention
An embodiment will be described with reference to FIGS. 1, 2, 3, 4, and 5. FIG. 1 is a block diagram showing an embodiment of a diversity apparatus according to the present invention, FIG. 2 is a flow chart showing the processing of a control unit, FIG. 3 is a diagram showing the directivity of an omnidirectional antenna and a directional antenna by phase shift combining. FIG. 4 is a flowchart showing an antenna group switching algorithm at the end of burst, and FIG. 5 is a perspective view of a portable wireless terminal of a digital wireless communication device having two antennas.

In FIG. 1, 10a and 10b are antennas, 11a and 11b are low noise amplifiers, 12a, 12b and 24 are switches, 15, 16a and 16b are 90-degree hybrids, 20a and 20b are frequency converters, and 21.
Reference numerals a and 21b are automatic gain adjusters, 22a and 22b are detectors, and 23 is a control circuit.

The radio waves received by the antennas 10a and 10b become electric signals, and are independently low-noise amplifiers 11a.
And 11b. As the antenna, a quarter-wave dipole antenna is used, and the antenna is placed upright with a quarter-wavelength. The output of the low-noise amplifier is connected to terminals 13a and 13b by change-over switches 12a and 12b.
Alternatively, it is connected to the terminals 14a and 14b. Terminal 13a
And 13b are paths for passing the antenna output as they are, and terminals 14a and 14b are paths for giving a phase difference by the 90-degree hybrid 15 and outputting a combined output of the two antennas. These outputs become the outputs 17a and 17b of the two systems by the 90-degree hybrids 16a and 16b. The antenna group switching output is used as the frequency converter 20.
Frequency conversion is performed by a and 20b.

After that, the amplitude is adjusted by the automatic gain adjusters 21a and 21b. The signals whose amplitudes have been adjusted by the automatic gain adjuster are detected by the detectors 22a and 22b. The amplitude of the input signal obtained by the automatic gain adjuster is input to the control circuit 23.

In the control circuit 23, as shown in FIG. 2, the amplitude value is input from the automatic gain adjuster in synchronization with the symbol timing (step 202). By comparing them, the switch 24 is operated so as to connect the detection output having a large amplitude to the signal output 25 (step 203). The total sum of the input amplitude values is calculated (step 204). The counter is incremented (step 205) and it is checked whether the counter has exceeded a certain value (step 206).

If it has not exceeded, the process returns to step 202. If it exceeds, it is the time to switch the antenna group, and therefore the average amplitude is calculated from the total sum of the amplitude values for the one with the largest sum (step 207), and the diversity antenna group switching control is performed (step 208). When that ends, the counter is initialized (step 209) and the process returns to step 202.

In FIG. 3, the antennas 10 and 11 are quarter dipoles, and the outputs of the terminals 31 and 32 are three.
00, the omnidirectional antenna is arranged at a distance from the space diversity, while the terminals 33, 3
4 is a directional diversity with antennas each having a directivity in the opposite direction (301, 302). Therefore, the switches 22 and 23 switch between space diversity and directional diversity.

In FIG. 4, when the antenna group switching control is started (step 210), 1 is added to the counter, the counter is updated (step 211), and the maximum average amplitude obtained in step 207 is stored in the memory. The maximum average amplitude when another diversity antenna group is adopted in the past is compared (step 212), and if the memory value is large, a signal is sent to the switches 12a and 12b to switch the diversity antenna group. If the memory value is small, it is checked whether the counter exceeds a certain value (step 213). If it exceeds, the diversity antenna group is switched. If it does not exceed, the current antenna group continues to receive signals. If the memory value is large in step 212, the antenna group is switched. When the antenna group is switched, the counter is initialized (step 216) and the average amplitude value of the memory is updated to the new value obtained in step 207 (step 21).
7).

According to this embodiment, the changeover switch 1
The input to the frequency converters 20a and 20b by 2a and 12b means that either the space diversity antenna or the directional diversity antenna is selected. By the way, the effect is different between the space diversity antenna and the directional diversity antenna depending on the arrival environment of radio waves. That is, in an environment in which one strong direct wave arrives, the directional diversity that allows the directional gain of the antenna to be obtained is advantageous. On the other hand, in an environment where standing waves have a very high standing wave ratio, it is more likely that the antenna is on the antinode of the standing wave than the directional diversity that receives the incident waves that oppose each other. Diversity is more advantageous. Therefore,
The diversity gain is improved by selecting the diversity antenna having a high received electric field by the switches 12a and 12b. In this case, it is necessary to switch the antenna in the high frequency part, and mixing of noise due to the switching is a problem. By the way, in a portable wireless device that does not move at high speed, the state of standing waves does not change drastically. Therefore,
Even if the diversity antenna group is switched for every certain burst, the characteristic is not significantly deteriorated. Even if a sudden change occurs, two uncorrelated diversity branches are independently demodulated by a plurality of subsequent frequency converters and demodulators, and switching diversity is performed after detection. The switching noise of is prevented.

The phase shifters 15a and 15b are fixed phase shifts of a quarter wavelength and can be realized by delay lines. In addition, the receiver is a 2-system system in spite of the diversity of 4 branches, which reduces the manufacturing cost and the power consumption of the apparatus.

The average amplitude of the currently unemployed antenna group stored in memory begins to deviate from its actual value if no switching occurs for a long period of time. In the present embodiment, the number of times that the same antenna group is continuously used is counted, and when the number exceeds a certain value, the antenna group is forcibly switched. This constant value differs depending on the environment in which the present invention is adopted. When the situation of the incident radio wave changes drastically, the effect of the present invention is lost unless the value is small. If the situation of the incident radio wave is gradual, the frequency of antenna group switching increases unless the value is large, resulting in switching noise. With this counter, the memory is regularly updated and appropriate switching can be performed.

<Embodiment 2> Another embodiment of the present invention will be described with reference to FIG. 6, 10a and 10b are antennas, 11a and 11b are low noise amplifiers, 1 is an antenna group switching circuit, 20a and 20b are frequency converters, 21
Reference numerals a and 21b are automatic gain adjusters, 30 is a control circuit, 31 is a switch, and 32 is a wave detector. Antennas 10a, 10
Two outputs of the radio wave received in b are obtained by the same antenna switching group circuit 1 as in the embodiment. These are input to the frequency converters 20a and 20b. After that, the amplitude is adjusted by the automatic gain adjusters 21a and 21b. The amplitude of the input signal obtained by the automatic gain adjuster is input to the control circuit 23. In the control circuit 23, the branch changeover switch 31 is changed over by the same branch changeover algorithm as in the embodiment. The received signal on the side connected by the switch 31 is detected by the wave detector 32 and becomes the signal output 25. Further, the control circuit controls the switching of the antenna group switching circuit 1 by the same antenna group switching algorithm as in the embodiment.

In the first embodiment, switching diversity is performed after detection, but in this embodiment, switching is performed before detection. In this case, switching noise in the switch 31 poses a problem, but the antenna group switching device 1 has already selected one with a high diversity effect, and the probability that the switch 31 will operate is low. Therefore, switching noise is suppressed. In this embodiment, only one detector is needed and the circuit scale can be made smaller than that in the first embodiment.

<Embodiment 3> Another embodiment of the diversity apparatus of the present invention will be described with reference to FIG. FIG. 7 is a time chart of the time division multiple access system. In FIG. 7, 406
Shows the switching state of the antenna group. Also, 40
Reference numerals 1, 402, 403, 404, and 405 denote communication bursts, and a guard time is provided between them. It is assumed that 401 and 404 are communication bursts of this terminal in the three-multiplex TDMA system. In the TDMA method,
Other than the communication burst, there is a free time during which another terminal is communicating. In the figure, the bursts 402, 403, and 404 correspond to this. In the embodiment, the management of the switching burst is performed in the control circuit, but this is synchronized with the burst of the TDMA system so that switching is performed outside the communication burst. This makes it possible to switch antennas in idle time and eliminate switching noise at all. In the figure, when the burst 401 ends, the antenna group switching routine is activated to switch to the antenna group 1. Also, when the burst 404 ends, the antenna group switching routine is activated to switch to the antenna group 2.

<Embodiment 4> Another embodiment of the diversity apparatus of the present invention will be described with reference to FIG. FIG. 8 is a time chart of the TDMA system, which also shows the preamble.

In FIG. 8, reference numeral 420 indicates the switching state of the antenna group. Also, 410, 412, 414, 4
16 and 418 are burst preambles of 4
Reference numerals 11, 413, 415, 417, and 419 denote data bursts, respectively.

If the antenna groups are not continuously switched, the average amplitude value before switching, which is stored in the storage means, does not match the actual situation, and switching is not performed by appropriate judgment. Therefore, it is necessary to periodically switch to update the accumulated average amplitude value.

In the first embodiment, a counter is provided in the control circuit to count the number of times that switching does not occur continuously, and when it exceeds a certain value, the diversity antenna group is switched. In the TDMA method, there is a unique word in the preamble. If this unique word detection is mistaken, the burst synchronization will be lost and it will have a significant effect.
To detect the unique word, it is better to perform reception with a more reliable antenna group. In this embodiment, the antenna group is compulsorily switched at a point before the end of the data burst by a fixed number of symbols, and the average amplitude value before the switching is updated. It is assumed that 410, 411, 416, and 417 are communication bursts.

Although the antenna group 2 is receiving at first, the antenna group is forcibly switched to the antenna group 1 in the middle of the data burst 411. As a result, the average amplitude value stored in the storage means is updated. At the end of the data burst 411, the antenna switching routine is activated, and the antenna group 2 is switched again from the comparison of the average amplitude values. Similarly, in the next data burst 417, the antenna group is forcibly switched to the antenna group 1 on the way.
As a result, the average amplitude value stored in the storage means is updated. When the data burst 417 ends, the antenna group switching routine is activated, and since the average amplitude of the antenna group 1 is higher than the average amplitude value this time, switching does not occur and the antenna group 1 continues to receive. ing.

As a result, the unique word is received by the good antenna group, and the detection probability becomes high. Switching noise occurs in the switched symbols due to the forced switching, but the switching frequency is suppressed to a constant value that is known in advance. Although the diversity antenna group which is not good is used for the reception by the compulsory switching, the diversity reception is performed before, and the characteristics are not rapidly deteriorated. Further, the average amplitude value before switching stored in the storage means can be updated for each burst, and it is possible to deal with a case where the fading frequency is relatively fast, or a case where the degree of multiplicity is high and the frame length is very long. The switching of the switch can be operated according to the judgment.

<Embodiment 5> Another embodiment of the present invention will be described with reference to the flowchart of the control circuit shown in FIG.

In the first embodiment, the means for detecting the average signal amplitude in the switching burst is provided as the means for detecting the quality of the received signal. Alternatively, the average signal amplitude ratio may be detected.

In FIG. 9, the amplitude value is input from the automatic gain adjuster in accordance with the symbol timing (step 2).
21). By comparing them, the switch 24 is operated to connect the detection output having a large amplitude to the signal output 25 (step 222). The total sum of the input amplitude values is calculated (step 223). The counter is incremented (step 224) and it is checked whether the counter has exceeded a certain value (step 225). If not, step 2
Return to 21. If it exceeds, it is time to switch,
An average amplitude ratio obtained by dividing a small sum of amplitude values by a large sum is calculated (step 226), and the control for switching the diversity antenna group is started (step 227). When that ends, the counter is initialized (step 228) and the process returns to step 221. Then, in the antenna switching group routine, control is performed so that an antenna group having a large average amplitude ratio is selected instead of the average amplitude.

In the case of the diversity antenna, this amplitude ratio has a very strong correlation with the maximum amplitude. Therefore, the diversity gain can be raised by the amplitude ratio as in the case of comparing the maximum amplitudes. If the amplitude ratio is large,
There is an advantage that the switching of the antenna branch in the base band is unlikely to occur, which is particularly effective when performing the pre-detection switching described in the other embodiments.

<Embodiment 6> Another embodiment of the present invention is shown in FIG.
The flow chart of the control circuit shown in FIG.

In the fifth embodiment, the means for detecting the average received signal amplitude ratio is provided as the means for detecting the received signal quality. Alternatively, the average signal amplitude difference may be detected.

In FIG. 10, the amplitude value is input from the automatic gain adjuster in accordance with the symbol timing (step 231). By comparing them, the switch 24 is operated so as to connect the detection output having a large amplitude to the signal output 25 (step 232). The sum total of the amplitude differences obtained at the time of comparison is obtained (step 233). The counter is incremented (step 234) and it is checked whether the counter has exceeded a certain value (step 235). If it has not exceeded, the process returns to step 231. If it exceeds, it is the time for switching, so the average amplitude difference is obtained from the sum of the differences in amplitude value (step 236), and the control for switching the diversity antenna group is performed (step 237). When that ends, the counter is initialized (step 238) and the process returns to step 231. Then, in the antenna switching routine, control is performed so that an antenna group having a large average amplitude difference is selected instead of the average amplitude.

Similar to the amplitude ratio, the amplitude difference has a very strong correlation with the maximum amplitude in the case of the diversity antenna. Therefore,
Diversity gain can be mentioned by the amplitude difference as well as by comparing the maximum amplitudes. Further, when the amplitude difference is large, there is an advantage that the switching of the antenna branch in the base band is unlikely to occur, which is particularly effective when switching before detection.

<Embodiment 7> Another embodiment of the present invention is shown in FIG.
This will be described with reference to the flow chart of antenna group switching shown in FIG. In FIG. 11, a big difference between the switching routines is that one flag is added.

When the switching control is started (step 240), 1 is added to the counter and the counter is updated (step 241), and the maximum average amplitude obtained in step 207 and the past stored in the memory are changed. The maximum average amplitude when the diversity antenna group is adopted is compared (step 242), and if the memory value is small, the flag is checked (step 243). The raising of the flag indicating that it is just after this forced switching will be described later.

If the flag is not set, it is checked whether the counter exceeds the specified value Ccf (step 24).
4). If it does not exceed, the current antenna group continues to receive. If the counter exceeds the specified value, the antenna group has been continuously selected for a long time, and there is a high possibility that the past maximum amplitude of the accumulating means actually does not meet,
Switch 12 to switch the diversity antenna group
A signal is sent to a and 12b (step 246). And
The process is ended by setting a flag indicating that the forced switching has been performed.

If the flag is set in step 243, it means that the switch has not been returned to the original antenna group immediately after the forced switch and has been switched. First, the flag is defeated (step 250). Next, since the past value has changed considerably and re-switching has not occurred, the specified value Ccf that causes forced switching is updated. in this case,
Divide by 2 to make an integer (Step 24)
9). Then, the reception with the current antenna group is continued. By changing the specified value, the cycle of forced switching is gradually shortened and the response becomes faster. On the other hand, switching noise becomes more frequent. If the memory value is large in step 242, the flag is checked (step 251). If the flag is not set, the specified value is updated to half value (step 251). Then, the antenna group is switched (step 2
55), the counter is initialized and the contents of the memory are changed (step 256). If the flag is set in step 251, the original antenna group is switched again immediately after the compulsory switching, and thus the change in the propagation environment is slow. Therefore, the flag is first turned over (step 253) and the specified value is updated (step 254). Further switch the antenna group (step 2
55), the counter is initialized and the contents of the memory are changed (step 256).

In this embodiment, the specified value has upper and lower limits so that it does not fall out of the range. While the increase in the specified value is gradual, the response in the decreasing direction is fast. This is to prevent the effect of the present invention from being weakened if the response to the case where the change is drastic is delayed. The upper and lower limits are provided in order to keep the frequency of switching noise below a certain level.

In this embodiment, the antenna group compulsory switching cycle can be controlled by the propagation state, and the antenna group compulsory switching can be performed at an appropriate cycle. As a result, a decrease in diversity gain is suppressed.

<Embodiment 8> Another embodiment of the present invention is shown in FIG.
The block diagram of the antenna group switching unit shown in FIG. In FIG. 12, 10a and 10b are antennas with different gains, 11a and 11b are low noise amplifiers, and 12a and 1b.
2b is a switch, 40, 43, 45 and 48 are phase shifters, 4
1, 49 are attenuators, and 44, 46 are amplifiers. Inputs 12a and 12b from the antenna are connected to terminals 13a and 13b or terminal 14 by changeover switches 12a and 12b.
a, 14b. The antenna 10a is an inverted F type antenna, and the antenna 10b is a half-wave dipole. These antennas are antennas having different gains, and the input 12a is an input from an inverted F-type antenna having a small antenna gain. The terminals 13a and 13b are paths for allowing the antenna output to pass through as they are, and the terminals 14a and 14b are paths for outputting a combined output through the phase shifters 40 and 45.

The input to the terminal 14a is divided into two by the 0-phase hybrid. One path is the phase shifter 40
The phase is delayed by 1/4 wavelength. Then, it is combined with the other half of the path of the other antenna and the 180 degree hybrid 42. If the gains of the antennas are different from each other, the directivity (301, 302) as in the first embodiment cannot be obtained even if they are combined. In the present embodiment, the attenuators 41 and 49 whose attenuation amounts are equal to the gain difference of the antennas and the amplifiers 44 and 46 whose amplification factors are equal to the antenna gain difference are loaded, and the directivity is corrected by matching their levels.

The sum and difference components are output to the output of the hybrid 42, and the sum component is sent to 19a, and the difference component is further sent to the terminal 19b by a quarter wavelength phase by the phase shifter 43. Is output. Similarly, the difference component from the hybrid 47 is sent to the terminal 19a through the phase shifter 48. The signal collected at the terminal 19a is level-corrected by the amplifier 44 and the attenuator 49, and the antenna input having the same directivity (301, 302) as in the first embodiment appears at the terminals 19a and 19b. Here, the levels of 19a and 19b differ by the amount of the difference in antenna gain, but the CNRs of the respective antennas are considered to be equal. In the control circuit, it is necessary to correct the amplitude value of each branch input by the amount corresponding to the antenna gain and then compare.

<Embodiment 9> Another embodiment of the present invention is shown in FIG.
Will be described. In FIG. 13, 10a and 10b are antennas having different gains, 11a and 11b are low noise amplifiers,
Reference numeral 1 is an antenna group switching circuit, and 3 is a receiver. The antenna 10a is an antenna having a small antenna gain.
At this time, it is necessary to correct the antenna gain as in the embodiment. In this embodiment, the gains of the low noise amplifiers 11a and 11b are changed by the antenna gain difference. This makes it possible to adjust the gain difference without adding an amplifier and an attenuator for gain adjustment in the antenna group switching unit. As a result, the directivity of 300, 301, 302 can be obtained by the same antenna group switching circuit as in the embodiment.

<Embodiment 10> Another embodiment of the present invention is shown in FIG.
4 and FIG. FIG. 14 is a block diagram showing another embodiment, and FIG. 15 is a block diagram of an antenna group switching circuit.

In FIG. 14, 10a and 10b are antennas, 11a and 11b are low noise amplifiers, 4 is an antenna group switching circuit, 3 is a receiver, and 5 is a transmitter. antenna
The signals input from 10a and 10b are input to the antenna group switching circuit 4 to form a desired antenna group. These signals are sent to the receiver 3 by the transmission / reception switch 51.
Are input to and received for diversity. Next time you send
The output from the transmitter 5 is transmitted with the same directivity as that of the receiving antenna system by including the switch 52 that realizes the antenna system at the time of reception and the transmitting antenna group switching circuit 4 that realizes the same antenna system.

In FIG. 15, reference numeral 15 is a 90-degree hybrid, and 61a and 61b are switches. In the antenna group switching circuit 1, what was synthesized by using the hybrids 16a and 16b is replaced by the switches 61a and 61b in this embodiment.
It is replaced with b. As a result, the antenna group switching circuit 4 becomes a bidirectional circuit and can be used for both transmission and reception.

According to the present embodiment, an environment in which the fading frequency is not high because the distance between the base station and the terminal station is not so large and the terminal does not move at high speed, for example, wireless communication indoors or a micro cell is adopted. In the mobile phone system described above, effective transmission of radio waves is performed, and transmission power can be reduced. It is also useful for effective use of frequencies.

The antenna group switching circuit 4 can be used even in the case of only receiving diversity. In this case, since the switch can be made smaller than the hybrid circuit, the circuit can be downsized.

In the above embodiments, the antenna is a quarter-wave dipole antenna, a half-wave dipole antenna, and an inverted F-type antenna, but another antenna such as a helical antenna may be used. You may try. When the two antennas used are of the same type, the same effect as the embodiment is obtained. When different types of antennas are used, the same effect as that of the embodiment can be obtained by adjusting with a low noise amplifier or adjusting within a switching circuit by an amplifier and an attenuator, as described in other embodiments. .

In the above embodiments, the present invention has been described by taking the case of two antennas as an example, but the present invention is also applicable to two or more antennas. As the number of antennas increases, sharpness is obtained in terms of directivity. Therefore, the effect of suppressing delayed waves becomes large due to the effect of directional diversity.

In the above embodiments, the antenna spacing and the phase shift amount in the hybrid are set to ¼ wavelength, but this is not the case. For example, set the antenna spacing to 3/8
The wavelength is used and 180 degrees hybrid is used for synthesis. Alternatively, if the antenna spacing is set to ⅛ wavelength and they are combined by a 270 degree hybrid, directional antenna outputs with low mutual correlation can be obtained.

In the above embodiments, the description has been given by taking the case of performing the switching diversity in the receiver 3 as an example, but the receiver performing the combining diversity can be substituted. Synthesis diversity has, for example, a synthesis method such as equal gain synthesis or maximum ratio synthesis, but particularly maximum ratio synthesis diversity, the saturation of diversity gain when the number of diversity branches is increased is slower than switching diversity,
The increase in diversity gain according to the present invention is remarkable. Therefore, good characteristics can be obtained.

In the above embodiments, the present invention has been described by taking the portable wireless terminal as an example, but the present invention can be applied to other wireless devices. One example is application to the base station 801 and data terminal 804 shown in FIG. In this case, signals are exchanged between the terminal and the base station, but it is possible to apply the base station only, or both the base station and the terminal, and the terminal only. This enables highly reliable communication in both transmission and reception directions between the base station-terminal and the terminal-terminal. In addition,
In the application at the base station, communication is performed simultaneously with a large number of terminals, and the diversity device is applied by time division or frequency division for each channel with each terminal.

[0098]

As described above, according to the present invention, the space diversity and the directional diversity can be selected to improve the diversity effect. Further, since the antenna groups are switched by burst, mixing of switching noise can be suppressed.

Further, the switching of the antenna group is performed in the high frequency band, so that the circuit scale of the subsequent stage can be suppressed. Therefore, the device manufacturing cost and power consumption can be reduced.

Furthermore, switching noise can be prevented by switching the plurality of branches in the antenna group after detection.

Further, also in the case of switching a plurality of branches in the antenna group before detection, switching is less likely to occur because the antenna group having a large diversity effect is selected beforehand, and switching noise is suppressed. It

Further, if transmission diversity is performed, it is possible to effectively use the frequency and save the transmission power.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of a diversity device of the present invention.

FIG. 2 is a flowchart showing an operation sequence of a control circuit of one embodiment of the diversity device of the present invention.

FIG. 3 is an explanatory diagram showing the directivity of the antenna of one embodiment of the diversity device of the present invention.

FIG. 4 is a flowchart showing an antenna group switching control sequence in the control circuit of one embodiment of the diversity device of the present invention.

FIG. 5 is a perspective view of a mobile wireless phone of the present invention.

FIG. 6 is a block diagram of another embodiment of the diversity device of the present invention.

FIG. 7 is a time chart showing a burst and a switching timing of antenna groups in multi-division multiple access communication in another embodiment of the diversity apparatus of the present invention.

FIG. 8 is a time chart showing a burst of time division multiple access communication and switching timing of antenna groups in another embodiment of the diversity apparatus of the present invention.

FIG. 9 is a flowchart showing the operation sequence of a control circuit of another embodiment of the diversity device of the present invention.

FIG. 10 is a flowchart showing an operation sequence of a control circuit of another embodiment of the diversity device of the present invention.

FIG. 11 is a flowchart showing an antenna group switching control sequence of another embodiment of the diversity device of the present invention.

FIG. 12 is a block diagram of an antenna group switching circuit of another embodiment of the diversity device of the present invention.

FIG. 13 is a block diagram of another embodiment of the diversity device of the present invention.

FIG. 14 is a block diagram of another embodiment of the diversity device of the present invention.

FIG. 15 is a block diagram of an antenna group switching circuit of another embodiment of the diversity device of the present invention.

FIG. 16 is an explanatory diagram of a system of another embodiment of the diversity device of the present invention.

[Explanation of symbols]

10a, 10b ... Antenna, 11a, 11b ... Low noise amplifier, 12a, 12b ... Antenna group changeover switch,
15 ... π / 4 hybrid circuit, 16a, 16b ... π /
4 hybrid circuit, 20a, 20b ... Frequency conversion circuit, 21a, 21b ... Automatic gain adjustment circuit, 22a, 22b
... detection circuit, 23 ... control circuit, 24 ... branch selection switch,
25 ... Signal output.

Claims (14)

[Claims] 1. A plurality of antennas spaced apart from each other,
Includes combining means for combining the output of each antenna through the phase shifter with at least one other antenna output, and selecting whether to output each antenna output through the combining means or directly output each antenna output An antenna group switching means, and a receiver for detecting the received signal quality of each output from the antenna group switching means and receiving switching diversity.
A storage unit that stores the received signal quality before the antenna group is switched by the antenna group switching unit, a received signal quality before the switching stored in the storage unit, and a received signal quality after the switching output by the diversity receiver are predetermined. A diversity apparatus comprising control means for controlling the antenna group switching means so as to switch to the antenna group including the branch having the highest received signal quality compared with each cycle. 2. The receiver according to claim 1, wherein the receiver includes a plurality of demodulators for demodulating each output from the antenna group switching means, a detecting means for detecting a received signal quality of each demodulator output, and the detecting means. A diversity device comprising branch switching means for selecting the best demodulator output among the received signal qualities detected by. 3. The receiver according to claim 1, wherein the receiver comprises a detection means for detecting the signal quality of each output of the antenna group switching means, and an antenna group switching means having the best signal quality detected by the detection means. A diversity device comprising branch switching means for selecting and outputting an output and a demodulator for demodulating the output of the branch switching means. 4. The diversity according to claim 1, further comprising control means for instructing the antenna group switching means to perform wireless communication by the time division multiple access method and switch the antenna group outside the burst used in the time division multiple access method. apparatus. 5. The diversity apparatus according to claim 4, further comprising control means for instructing the antenna group switching means to perform switching in a fixed time before the end of the use burst, in addition to the antenna group switching outside the burst. 6. The average according to claim 1, wherein the receiver performs diversity reception by switching each output from the antenna group switching means according to a received signal level, and time-averages the received signal levels obtained from the receiver over a certain period. And a means for controlling the antenna group switching means according to an average received signal level as received signal quality. 7. The receiver according to claim 1, wherein the receiver performs diversity reception by switching each output from the antenna group switching means according to a reception signal level, and the maximum reception signal level among the reception signal levels obtained from the receiver. Diversity device comprising arithmetic means for taking two ratios and averaging means for time-averaging the ratios obtained by the arithmetic means for a certain period, and controlling the antenna group switching means by the average received signal level ratio as the received signal quality. . 8. The receiver according to claim 1, wherein each of the outputs from the antenna group switching means is switched according to a reception signal level to perform diversity reception, and the maximum reception signal level among the reception signal levels obtained from the receiver. And a mean for averaging the received signal level difference obtained by the calculating means over time for a certain period, and controlling the antenna group switching means by the average received signal level difference as received signal quality. Diversity device to do. 9. The counting means for counting the number of times that the antenna group is not continuously switched in the control means, and the antenna group switching means forcibly forcing the antenna group to switch when the counting means counts a fixed number. A diversity device having interrupting means for switching. 10. The counting means for counting the number of times that the antenna group has not been switched continuously in the control means, and the antenna group switching means forcibly switching the antenna group when the counting means counts a prescribed number. ,
A diversity device comprising interrupt control means for changing the specified count number of the counting means according to the switching state. 11. A plurality of antennas having different gains placed apart from each other, a synthesizing means for synthesizing the output of each antenna through at least one other antenna output through a phase shifter, an attenuator and an amplifier. Antenna group switching means for selecting whether to output the output of the antenna through the combining means or directly outputting the output of each antenna, and a receiver for receiving diversity by switching each output from the antenna group switching means according to the received signal level. An arithmetic means for taking the difference between the two received signal levels with the maximum level among the received signal levels output by the receiver; an averaging means for averaging the received signal level differences obtained by the arithmetic means over a fixed period; and antenna group switching Means for accumulating the average received signal level difference which is the output of the averaging means before the antenna group is switched by the means, and said accumulating means The accumulated average reception signal level difference before switching the antenna group and the average reception signal level difference after switching the antenna group output by the averaging means are compared for each predetermined period to obtain the antenna group including the branch with the highest reception signal level difference. A diversity apparatus comprising control means for controlling the antenna group switching means so as to perform switching. 12. A plurality of antennas having different gains, which are placed apart from each other, a plurality of low noise amplifiers whose gains are adjusted so as to correct the antenna gains of the respective antenna outputs, and each of the low noise amplifiers. Combining means for combining the output with at least one other antenna output through a phase shifter, and antenna group switching for selecting whether to output each antenna output through the combining means or directly output each antenna output Means, a receiver for diversity receiving each output from the antenna group switching means according to the received signal quality, a storage means for storing the received signal quality before the antenna group is switched by the antenna group switching means, and the storage Received signal quality before switching stored in the means and received signal after switching output by the diversity receiver Diversity apparatus characterized by comprising a control means for controlling the antenna group switching means to switch the antenna group including a branch highest received signal quality by comparing the quality for each predetermined period. 13. The receiver according to claim 1, further comprising detection means for performing maximum ratio combining diversity reception on each output from the antenna group switching means and detecting the signal quality of the maximum ratio combined signal output. A diversity device for controlling the antenna group switching means so as to switch to the antenna group having the highest signal quality. 14. The diversity device according to claim 1, further comprising a transmitter for transmitting a radio wave from an antenna branch in an antenna group selected by the receiver.