JPH03201629A - Space diversity control system - Google Patents

Abstract

PURPOSE:To reach a receiving state to an in-phase condition without fail and to enable reception in the most satisfactory state by increasing a step phase shift amount for a prescribed amount by a perturbation method so that the change direction of a relative phase between first and second communication systems according to the perturbation method can be a normal state to alternate ly repeat increasing and decreasing directions. CONSTITUTION:This system is provided with a detecting means 82 to detect whether or not the changing direction of the relative phase between the first or second communication system according to the perturbation method is turned to the normal state to alternately repeat the increasing and decreasing directions, and a phase shift amount control means 72 to variably control the phase shift amount per step according to the perturbation method. When it is detected by the detecting means 82 that the normal state is obtained, the phase shift amount control means 72 increases the phase shift amount per step according to the perturbation method by the prescribed amount. Thus, even when the detection limit of reception level deviation is present thereon, the receiving state can read the in-phase condition without fail and the reception can be executed in the most satisfactory state.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a space diversity control scheme used in a wireless communication system.

(Prior Art) In wireless communication systems, space diversity is widely used as a method for reducing the effects of fading, and one of these methods employs a control method called a perturbation method. This perturbation method is used to control the relative phase between two communication systems in which antennas are spaced apart, and the amount of phase shift of this relative phase is adjusted to an extent that does not affect the main signal. Each time the relative phase is changed by this amount of phase shift, the change in the reception synthesis output level of each communication system is detected, and based on the degree of improvement, for example, the above-mentioned one that satisfies the in-phase synthesis condition This determines the direction of change in relative phase.

Figure 4 shows the configuration of a transmission space diversity wireless communication system to which this perturbation control method is applied, where 1 is a transmitting device equipped with two spatially separated antennas, and 2 is a receiving device. , 3 indicate control lines, respectively.

First, the transmitting device 1 splits an intermediate frequency signal outputted from a modulation circuit (not shown) into two at a divider 11, and combines one of them with a local oscillation signal from a transmitting local oscillator 13 at a transmitting frequency converter 12a. After frequency conversion, the signal is amplified by a high frequency power amplifier 15a and transmitted from the main transmitting antenna 16a to a wireless line. Further, the other of the two branched intermediate frequency signals is synthesized with the local oscillation signal whose phase has been controlled by the phase shifter 14 in the transmission frequency converter 12b, frequency-converted, and then amplified in the transmission power amplifier 15b and It is transmitted from the transmitting antenna 16b to a wireless line.

Incidentally, the amount of phase shift of the phase shifter 14 is controlled by a phase shift control circuit 17.

On the other hand, the receiving device 2 receives a signal that has arrived via a wireless line, receives it with an antenna 21, amplifies the received signal with a low-noise amplifier 22, and then uses a receiving frequency converter 23 to generate a local signal generated from a receiving local oscillator 24. Combines with oscillation signal and converts frequency. The intermediate frequency signal thus obtained is level-controlled by an automatic gain control amplifier 25 and then output to a demodulation circuit (not shown). The receiving device 2 also includes a control direction detection circuit 26 . This control direction detection circuit 26 consists of a comparison control section and a modulation section.

In the comparison control section, the AGC of the automatic gain control amplifier 25
The voltage is monitored and a phase shift control direction is determined in a direction that achieves in-phase synthesis. This phase shift control information is subjected to, for example, FSK modulation in the modulation section and output to the control line 3.

The control line 3 includes a transmitter 31 installed on the receiving device 2 side, a receiver 34 installed on the transmitting device 1 side, and a control transmission line between the transmitter 31 and the receiver 34. There are connections. Then, the phase shift control information output from the control direction detection circuit 26 of the receiving device 2 is transmitted to the phase shift control circuit 17 of the transmitting device 1. Note that 32 and 33 are antennas for control lines, respectively.

In such a configuration, the receiving device 2 monitors the combined reception level of the main transmission wave and the sub-transmission wave from the transmitting device 1 at a predetermined step period by the control direction detection circuit 26, and uses the monitoring result to determine the combined reception level of the main transmission wave and the sub-transmission wave. In the direction of increasing reception level,
That is, the transfer control direction of the next step is determined in the direction of approaching the in-phase synthesis condition, and phase shift control information representing this phase shift control direction is transmitted to the transmitter 1 via the control line 3.

On the other hand, the transmitting device 1, in accordance with the phase shift control direction notified from the receiving device 2 through the transfer control path 17, increments the phase shift amount Δθ for one step set in advance in a circular manner at the step period. The phase shift of the phase shifter 14 is variably controlled.

Therefore, if the reception phase of the main transmission wave A and the sub-transmission wave B from the transmitter 1 received by the receiver 2 has a phase difference θ as shown in FIG. For example, if the value corresponds to point A in FIG. Device 1 is notified. Then, in the transmitting device 1, the phase shift of the phase shifter 14 is varied by Δθ in the leading direction according to the phase shift control direction notified from the receiving device 2, and thereby the phase of the sub-transmission wave B is variably controlled in the leading direction. Ru. Therefore, the main transmission wave A and the sub-transmission wave B in the receiving device 2
The reception level of the composite wave with Δθ increases by an amount corresponding to Δθ, and approaches the in-phase condition shown at the point B.

Thereafter, in the same way, the phase of the sub-transmission wave B transmitted from the transmitter 1 is variably controlled in the advancing direction by Δθ at every step.
As a result, the relative level of the composite wave of the main transmission wave A and the subcarrier B in the receiving device 2 gradually increases as shown in FIG. 6, and the reception condition gradually improves toward the in-phase condition.

On the other hand, when the reception phase of the composite wave in the receiver 2 is at the 0 point, the receiver 2 transmits phase shift control information for delaying the phase of the sub-transmission wave to the transmitter 1, and as a result, the transmission The phase of sub-transmission wave B transmitted from device 1 is 1
Each step is controlled in the delay direction. Therefore, in this case, the relative level of the received combined wave gradually increases from point 0 to point C in FIG. 6, thereby improving the received tls9 toward the in-phase condition.

However, such conventional control methods have the following problems. In other words, as the relative level of the composite wave approaches the in-phase condition, the amount of change in level per step, that is, the received level deviation, becomes very small, and depending on the value of the phase shift amount Δθ per step, the amount of change in level per step, that is, the reception level deviation, becomes very small. receiving device 2
may fall below the detection limit ΔL by the control direction detection circuit 26. In this way, when the amount of change in the relative level of the composite wave becomes below the detection limit, the control direction detection circuit 26
determines that there is no improvement and notifies the transmitter 1 to reverse the phase shift control direction. Therefore, the transmitter f
The phase shift control by the phase shift control circuit 17 of il is in a steady state in which the advance direction and the delay direction are alternately repeated, as shown in FIG. Therefore, although the receiving condition of the system has not completely reached the in-phase condition, it is not improved any further, and as a result, reception cannot be performed under the best conditions.

(Problems to be Solved by the Invention) As described above, in the conventional control method, due to the detection limit of received level deviation, the phase shift control operation reaches a steady state before the in-phase condition is satisfied. The problem was that it could not be realized.

Therefore, the present invention focuses on this point, and provides a space diversity control method that enables the receiving state to reach the in-phase condition reliably even if there is a detection limit for received level deviation, thereby allowing reception to be performed in the best possible state. The purpose is to

[Structure of the invention] (Means for solving the problem) In order to achieve the above object, the present invention provides a first method using a perturbation method.
and a detection means for detecting whether or not the direction of change in the relative phase between the second communication systems has reached a steady state in which the direction of change in the relative phase alternately repeats an increasing direction and a decreasing direction, and a variable amount of phase shift per step using a perturbation method. and phase shift amount control means. When the detection means detects that a steady state has been reached, the phase shift amount control means increases the step phase shift amount by the perturbation method by a predetermined amount.

Another aspect of the present invention provides a first detection method for detecting whether or not the direction of change in the relative phase between the first and second communication systems by the perturbation method has reached a steady state in which an increasing direction and a decreasing direction are alternately repeated. means, a second detection means for detecting whether the direction of change in relative phase between the first and second communication systems by the perturbation method is in a constant direction, and a phase shift control amount per step by the perturbation method. and a phase shift control means for variably controlling. The phase shift control means increases the step phase shift amount by a predetermined amount by the perturbation method when the first detection means detects that the relative phase change has reached a steady state, and the step shift amount is increased by a predetermined amount. When the second detection means detects that the direction of change in the relative phase becomes a constant direction after the phase amount increase control, the step phase 11 is returned to the amount before the increase.

(Effect) As a result, even if the reception level deviation exceeds the detection limit during phase shift control using the perturbation method and the phase shift control operation reaches a steady state before reaching the in-phase condition, this steady state will not be detected. Then, the amount of phase shift per step is changed to a large value.

Therefore, in subsequent steps, the received level deviation increases in accordance with this large amount of phase shift and exceeds the detection limit, thereby making it possible to break out of the steady state and bring the receiving state closer to the in-phase state.

Furthermore, when the direction of change in relative phase becomes constant, the step phase shift amount is returned to the small value before the increase, so when the reception state is far from the in-phase condition, the phase shift will be controlled by a small step phase shift amount. This prevents the problem that the received level deviation becomes too large to be detected.

(Embodiment) FIG. 1 shows the configuration of a phase shift control circuit of a transmission space diversity wireless communication system to which a space diversity control method is applied in an embodiment of the present invention. Note that the other parts of the system are the same as the configuration shown in FIG. 4, so detailed explanation thereof will be omitted.

The phase shift control circuit of this embodiment includes a phase shift control section 71 and a phase shift amount control section 72. First, the shift amount control unit 71 includes an up/down counter 73 that outputs a phase shift control signal to the phase shifter 14, and information indicating a phase shift control direction sent from the receiving device 2 via the control line 3. 1” (advance)
It is comprised of two discriminators 74 and 75 that identify whether the clock is "0" or "0" (delayed), and a clock component extraction circuit 76 that generates one clock for each step. Note that the AND gate shown in 77.78 applies to each discriminator 74 described above.
．． It is made conductive in response to the detection output of the clock component extraction circuit 75 and supplies the clock generated from the clock component extraction circuit 76 to the up/down counter 73.

Next, the phase shift/quantity control unit 72 includes a 4-bit counter 79 that counts the clock generated from the clock component extraction circuit 76, and a 4-bit counter 79 that is opened while these seven 4-bit counters are counting the clock by 4 bits. receiving device 2
It is composed of a gate circuit 80 that passes phase shift control information from the integrator 81, and a zero level detector 82.

Of these, the integrator 81 integrates 4 bits of phase shift control information input manually via the gate circuit 80 and supplies the integrated output to the zero level detector 82. The zero level detector 82 determines whether the integrated output level from the integrator 81 is O, and if it is O, changes the step count number of the up/down counter 73 from 1 bit to 2 bits. .

Note that the receiver 34 of the control line 3 performs FSX demodulation on the phase shift control information sent from the receiving device 2, and the demodulation result is "1".
When it is (advance), it outputs a voltage of +V, while when it is "0" (lag), it outputs a voltage of -■.

With such a configuration, when the phase shift control information of "1" or "O" is continuously received from the receiving device 2, the integrator 81 receives the "1°" or "0" phase shift control information. The corresponding voltage of +V or -V is continuously supplied. Therefore, the integrated output of the integrator 81 is, for example, during the period T in FIG.
As shown in the figure, the voltage becomes positive or, conversely, it becomes a negative voltage and does not become 0.'' Therefore, the zero level detector 82 outputs a zero level non-detection signal, that is, a signal that causes counting to be performed with a small step width. As a result, the up/down counter 73 counts 1 for each clock, for example. Therefore, at this time, the shift Hj mΔθ1 of the phase shifter 14 per step is calculated by the up/down counter 73, for example.
If it is 8 bits, it will change by (360°/28) for each step. The DO-DI section in FIG. 2 shows changes in the relative level of the composite wave due to the above control operation.

Now, in this state, the reception level deviation ΔL1 of the composite wave per step exceeds the detection limit of the control direction detection circuit 26, for example between D and D2 in FIG. When a steady state is reached in which the delay direction and the delay direction are alternately repeated, the integral output of the integrator 81 becomes 0 in four steps as shown in FIG. Then, at this point, a detection signal is generated from the zero level detector 82, and as a result, the counting operation of the up/down counter 73 is changed to, for example, two counts every one clock. Therefore, from now on, the phase shift control information supplied from the up/down counter 73 to the phase shifter 14 changes by a phase shift amount Δθ2, which is twice the phase shift amount Δθ1 before reaching the steady state, for each step. For this reason, the phase shift of the phase shifter 14 changes by 2X (360°/28) for each step, and as a result, D1 to D in FIG.
As shown between 3 and 3, the reception level deviation ΔL2 between steps in the receiving device 2 increases. Therefore, the received level deviation returns to within the detection limit of the control direction detection circuit 26, and as a result, the control direction detection circuit 26 is again able to detect the phase shift control direction.

Therefore, the phase of the sub-transmission wave B is further variably controlled in the advancing direction, and as a result, the relative level of the composite wave further approaches the maximum value, and the reception state is finally close to the in-phase condition as shown in Figure 2. reach the point.

In this embodiment, when the change in the phase shift control direction determined by the control direction detection circuit 26 of the receiving device 2 reaches a steady state, the phase amount per step is doubled. As a result, the level deviation of the receiver 13 by one step can be increased to return it to within the detection limit of the control direction detection circuit 26, and the detection operation of the phase shift control direction by the control direction detection circuit 26 can be restarted. . Therefore, from now on, the phase shift control circuit 17 of the transmitting device 1 can further perform variable control of the phase shift toward the in-phase condition, and as a result, it is possible to finally reach a point close to the in-phase condition.

Note that the present invention is not limited to the above embodiments. For example, in a phase shift control operation after increasing the phase shift amount, if the phase shift control direction continues for a certain number of steps or more, at that point the phase shift amount per step is returned to the value before the increase. You can. By doing this, for example, if the fading state changes and the relative level of the composite wave decreases greatly, problems such as the reception level deviation of one step becoming too large to be detected by the control direction detection circuit 26 can be avoided. It can be prevented.

Further, in the embodiment described above, the case where the phase shift amount is changed in two steps has been described, but it may be changed in three or more steps. Thereby, even if the detection limit of the control direction detection circuit is relatively large, the in-phase condition can be reliably realized. Furthermore, in this case, the amount of change in the amount of phase shift at each stage does not need to be constant, and may be increased as the amount of phase shift increases. In addition, the condition for changing the amount of phase shift was when the steady state reached 4 consecutive steps, but it may also be less than 3 steps or more than 5 steps <II:
Can be set at will.

Further, in the above embodiment, the case where the present invention is applied to a transmission space diversity system has been described, but the present invention may also be applied to a reception space diversity system.

In addition, the structure of the steady state detection means, the structure of the phase shift control means, etc. can be modified in various ways without departing from the gist of the present invention.

[Effects of the Invention] As detailed above, the present invention is capable of determining whether a steady state is reached in which the direction of change in the relative phase between the first and second communication systems alternately increases and decreases using the perturbation method. and a phase shift amount control means for variably controlling the amount of phase shift per step using a perturbation method. When the detection means detects that a steady state has been reached, the phase shift amount control means increases the step phase shift amount by the perturbation method by a predetermined amount.

Another aspect of the present invention provides a first detection method for detecting whether or not the direction of change in the relative phase between the first and second communication systems by the perturbation method has reached a steady state in which an increasing direction and a decreasing direction are alternately repeated. means, second detection means for detecting whether the direction of change in relative phase between the first, second and second communication systems is in a constant direction by the perturbation method, and phase shift control per step by the perturbation method. and phase shift control means for variably controlling ffi.

The phase shift control means increases the step phase shift amount by a predetermined amount by the perturbation method when the first detection means detects that the relative phase change has reached a steady state, and the step shift amount is increased by a predetermined amount. When the second detection means detects that the direction of change in relative phase has become constant after the dose increase control, the step phase amount is returned to the amount before the increase.

Therefore, according to the present invention, even if there is a reception level deviation detector W, it is possible to ensure that the reception state reaches the (I) condition, thereby achieving space diversity control that allows reception to be performed in the best condition. method can be provided.

[Brief explanation of drawings]

FIG. 1 is a circuit block diagram showing the configuration of a phase shift control circuit of a system to which a space diversity control method is applied in an embodiment of the present invention, and FIGS. 2 and 3 are diagrams for explaining the same control method, respectively. , Fig. 4 is a schematic configuration diagram of a transmission space diversity wireless communication system that employs a control method using the perturbation method, Fig. 5 is a diagram showing the reception phase difference between the main transmission wave and the sub-transmission wave, and Figs. 6 and 7. Each figure is a diagram for explaining the problems of conventional control methods. DESCRIPTION OF SYMBOLS 1... Transmission device, 14... Phase shifter, ■7... Shift control circuit, 2... Receiving device, 26... Control direction detection circuit, 3... Control line, 71 ...phase shift control section, 7
2... Phase shift amount control unit, 73... Up/down counter, 74° 75... Discriminator, 76... Clock component extraction circuit, 80... Gate circuit, 81... Integrator,
82...Zero level detector, Δθ, Δθ1. Δθ2・
...Amount of phase shift.

Claims (2)

[Claims] (1) A space for controlling the relative phase between the first and second communication systems by a perturbation method according to the amplitude level of the combined output of the reception output by the first communication system and the reception output by the second communication system. In the diversity control method, a detecting means for detecting whether or not a direction of change in the relative phase between the first and second communication systems by the perturbation method has reached a steady state in which an increasing direction and a decreasing direction are alternately repeated; A space diversity control system comprising: a phase shift amount control means for increasing the step phase shift amount by the perturbation method by a predetermined amount when a steady state is detected by the detection means. (2) A space for controlling the relative phase between the first and second communication systems by a perturbation method according to the amplitude level of the combined output of the reception output by the first communication system and the reception output by the second communication system. In the diversity control method, a first detection means detects whether a direction of change in the relative phase between the first and second communication systems by the perturbation method has reached a steady state in which an increasing direction and a decreasing direction are alternately repeated. and a second detection means for detecting whether the direction of change in the relative phase between the first and second communication systems by the perturbation method is in a constant direction, and a change in the relative phase by the first detection means. is detected to be in a steady state, the step phase shift amount by the perturbation method is increased by a predetermined amount, and after controlling the increase in the step phase shift amount, the second detection means detects the direction of change in the relative phase. 1. A space diversity control method, comprising: phase shift amount control means for returning the step phase amount to the amount before the increase when it is detected that the step phase amount is in a constant direction.