JPH07177059A - Transmitter-receiver - Google Patents

Abstract

PURPOSE:To control the transmission power at a high speed with a high precision by selecting hopping patterns which don't overlap a', the same time between an outgoing line an incoming line and multiplexing them in the same frequency band. CONSTITUTION:A reception hopping pattern 6 is delayed by a delay circuit 20 to generate a hopping pattern 18 for transmission. A synthesizer 17 is driven by a frequency control circuit to switch the frequency of the carrier in accordance with the pattern 18, and an intermediate frequency signal 16 is converted into a radio frequency signal 19 by frequency conversion. A hopped signal is inputted to a level control circuit 21. Meanwhile, a level estimating circuit 24 uses the reception power level for each hopping obtained by a level detecting circuit 12 to estimate the line condition of each transmission hopping frequency and outputs the result to the level control circuit 21. The level control circuit 21 controls the transmission power level of the transmission signal 19 after hopping so that the reception side can obtain a prescribed reception power level even in the line condition estimated by the level estimating circuit 24.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a frequency hopping / spread spectrum transmission / reception device used in mobile communication such as digital car telephones and mobile telephones.
It is configured so that transmission power control as a measure against fading can be easily implemented.

[0002]

2. Description of the Related Art In the frequency hopping spread spectrum system, the frequency of a carrier wave used for modulating a digital signal is changed with time. Therefore, it is possible to avoid staying at a frequency with a poor communication state, and it is possible to average the communication quality.

As shown in FIG. 8, a transmitter / receiver adopting a conventional frequency hopping / spread spectrum system has a transmitter 31
Includes a coder 33 for coding the transmission data 32, a modulator 34 for modulating the coded signal into an intermediate frequency signal 35, and a frequency synthesizer 36 for frequency converting the intermediate frequency signal 35 into a radio frequency signal 39. A frequency control circuit 37 for controlling a carrier frequency used for frequency conversion of the frequency synthesizer 36, a band pass filter (BPF) 40 for cutting extra signals, and an antenna 41 for transmitting and receiving radio waves are provided.

On the other hand, the reception side 42 multiplies the reception signal 44 of radio frequency by multiplying the BPF 43 for cutting extra signals from the reception signal, the synchronization circuit 45 for establishing synchronization based on the reception signal 44, and the carrier frequency. A frequency synthesizer 48 for converting to the intermediate frequency signal 49, a frequency control circuit 46 for switching the frequency of the carrier wave used by the frequency synthesizer 48 for frequency conversion in the same pattern as the transmitting side, and a demodulator 50 for demodulating the intermediate frequency signal 49, Decoder 51 for decoding the original data
It has and.

As illustrated in FIG. 9, the frequency control circuit 37 sequentially switches the carrier frequency in the frequency synthesizer 36 to f1, f2, f3 and f4 every time a fixed time elapses. This frequency changing pattern (frequency hopping pattern) is predetermined. The minimum unit of the frequency hopping pattern (the duration of the same frequency) is called a hop. FIG. 9 shows a hopping pattern of T = 4 hops.

In the transmitter / receiver shown in FIG. 8, the encoder 33 encodes the transmission data 32 of (0, 1) input to the transmitter 31 and the modulator 34 modulates the intermediate frequency signal 35. On the other hand, the frequency synthesizer 36 is driven by the frequency control circuit 37, switches the frequency of the carrier wave according to a predetermined frequency hopping pattern 38, and outputs the intermediate frequency signal 35.
Is converted into a radio frequency signal 39. The converted signal then passes through a bandpass filter 40 and the antenna.
Sent from 41.

On the receiving side 42, a synchronizing circuit 45 establishes synchronization with a received signal 44 that has passed through the band pass filter 43, and then a frequency control circuit 46 causes a frequency synthesizer.
48 is driven and converted into an intermediate frequency signal 49 according to the same frequency hopping pattern 47 as the transmitting side. Further, demodulator 50 performs demodulation, and decoder 51 restores the original data 52.
Convert to.

In order to enable bidirectional communication, a conventional mobile telephone transmitter / receiver adopting a frequency hopping / spread spectrum system is provided with an uplink from a mobile station to a base station and from a base station as shown in FIG. With the downlink to the mobile station,
The hopping pattern is set using different frequency bands. Therefore, the frequency synthesizer 38 on the transmitting side 31 of the base station and the frequency synthesizer 38 on the receiving side 42 of the mobile station.
48 is controlled so as to switch the carrier frequencies in the order of F1, F2, F3, F4, while the frequency synthesizer 48 of the transmitting side 31 of the mobile station and the frequency synthesizer 48 of the receiving side 42 of the base station are f1, f2, The carrier frequency is controlled to be switched in the order of f3 and f4.

As a spread spectrum method using the same frequency band in the uplink and the downlink,
Conventionally, the TDD method is known. In this method, not the frequency hopping signal but the direct spread signal is used to perform the spread spectrum, and as shown in FIG.
Transmission and reception are switched by switching and time division is performed.

In this system, since the time is divided into two and allocated to transmission and reception, the transmission side temporarily stores the transmission signal in the memory, forms it into a packet, and transmits it at a double speed. The receiving side needs to store the received signal in the memory and then read it while adjusting the time.

Therefore, a transmitter / receiver adopting this method is
A mechanism for processing signals in packets or for doubling the transmission speed, a switch operation mechanism for turning transmission on / off, and the like are required, which complicates the configuration.

[0012]

A conventional transmitter / receiver using a frequency hopping spread spectrum signal is a TDD.
Although it has an advantage that the configuration is simpler than the system, the following problems arise because the frequency bands used by the uplink and the downlink are different.

In mobile communication, as a measure against fading that causes deterioration of line quality, transmission power control is performed to compensate for level fluctuations in received signal power due to fading by adjusting transmission power.

When this transmission power control is performed by a conventional transmitter / receiver using a frequency hopping spread spectrum signal, the following procedure is taken.

First, the mobile station transmits a signal to the base station.
The base station which receives this estimates the uplink channel condition from the received signal power from the mobile station, and transmits that information to the mobile station through the downlink. The mobile station that received this
The transmission power is controlled based on the information.

Since such a procedure is performed, the mobile station controls the transmission power based on the past channel status (propagation status) for the propagation time from the base station to the mobile station, and the signal power level fluctuation due to fading occurs. It becomes difficult to follow this when the speed becomes high.

Further, on the transmitting side, since frequency slots obtained by dividing a wide frequency band into a large number are used by switching according to a hopping pattern, fading compensation information regarding all the frequency slots is transmitted from the base station to the mobile station. When trying to send, the amount of control information to be put on the downlink becomes very large.

The present invention solves these conventional problems, and an object of the present invention is to provide a transmitter / receiver having a simple structure capable of performing high-speed and highly accurate transmission power control.

[0019]

Therefore, in the present invention, in a transmitting / receiving apparatus for transmitting / receiving a signal by a frequency hopping spread spectrum system, each hopping pattern used on the transmitting side and the receiving side is a frequency belonging to the same frequency band. And the level detection means for detecting the received power level at each hopping frequency of the received signal, and the detection by the level detection means, while the frequency is selected so that the frequencies of both hopping patterns at the same time do not overlap. And level control means for controlling the transmission power for each hopping frequency using the above information.

Further, the transmitting side is configured to use the hopping pattern used on the receiving side with a delay of N hops (N is an integer) as the hopping pattern.

Further, the level detection means detects the reception power level of each symbol within one hop, and the level control means performs the transmission power control based on the average value of the reception power levels of a fixed number of symbols. I am configuring.

Further, the level detecting means detects the received power level of each symbol within one hop, and the level control means obtains the received power level obtained from the moving average of the received power levels in a fixed number of symbols and its change. The transmission power control is performed based on the quantity.

Further, in this case, the level control means decreases the transmission power level in the transmission power control with time when the change amount increases, and when the change amount decreases, the transmission power level is temporally constant. Configured to keep.

[0024]

Therefore, the line condition when transmitting a signal at each hopping frequency can be immediately grasped from the received power level of the received signal. Therefore, it becomes possible to quickly execute highly accurate transmission power control.

The hopping pattern used on the transmitting side is N more than the hopping pattern used on the receiving side.
When delayed by hops (N is an integer), the transmission power can be controlled by always referring to the reception power level N hops before the signal transmission.

In the case of the low-speed frequency hopping spread spectrum system in which the hop length is set to several times the symbol length of the transmission data, the received power level of each symbol within one hop is detected and the fixed number of symbols The reception power level at the time of transmission is estimated based on the average value of the reception power level, and the transmission power level is set accordingly.

Further, in this case, by taking a moving average of a fixed number of symbols, the amount of change in the received power level at the time of transmission can be estimated together, and the transmission power control can be executed more precisely. .

Further, when the moving average of this symbol indicates an increase, it is considered that the reception power level at the time of transmission also increases, and the transmission power level is set accordingly. However, when the moving average of symbols shows a decrease, a sharp change in the received power level at the time of transmission is expected, so by keeping the transmission power level constant, the estimated value and the actual value will be large. Avoid divergence.

[0029]

【Example】

(First Embodiment) FIG. 1 shows the configuration of a transmitter / receiver 1 in a mobile station as an embodiment of the transmitter / receiver of the present invention.

This transmitter / receiver 1 has, on the transmitting side, an encoder 14 for encoding the transmission data 13 and an intermediate frequency signal.
A modulator 15 that modulates to 16; a frequency synthesizer 17 that frequency converts the intermediate frequency signal 16 into a radio frequency signal 19; and a frequency synthesizer according to a frequency hopping pattern.
Frequency control circuit 5 for controlling switching of 17 carrier frequencies
A delay circuit 20 for delaying the control signal output from the frequency control circuit 5 and inputting it to the frequency synthesizer 17, and a level estimation circuit 24 for estimating the line status for each transmission hopping frequency using the detected received power level, Level estimation circuit
A level control circuit 21 for controlling the transmission power level so as to compensate for the line condition estimated by 21, a BPF 22, and an antenna 23 are provided.

Further, on the receiving side, a frequency synthesizer for converting the received signal 3 into an intermediate frequency signal 8 under the control of switching of the carrier frequency by the BPF 2 connected to the antenna 23, the synchronizing circuit 4, and the frequency control circuit 5. 7, a demodulator 9, a decoder 10 for outputting reception data 11, and a level detection circuit 12 for detecting the reception power level of the intermediate frequency signal 8.

In the receiver of the transmitter / receiver 1, upon receiving a signal, the synchronizing circuit 4 establishes synchronization based on the received signal 3 after passing through the BPF 2, the frequency control circuit 5 drives the frequency synthesizer 7, and the frequency A synthesizer 7 converts the received signal 3 into an intermediate frequency signal 8 according to a defined frequency hopping pattern 6. Further, the demodulator 9 performs demodulation, and the decoder 10 decodes the received data 11. Also,
The level detection circuit 12 obtains the received power level for each hop of frequency hopping in the intermediate frequency signal 8.

On the other hand, in the transmission section, the encoder 14 transmits the transmission data.
13 is coded and further modulated by a modulator 15 into an intermediate frequency signal 16. The frequency synthesizer 17 is driven by the frequency control circuit 5, switches the frequency of the carrier according to the frequency hopping pattern 18, and frequency-converts the intermediate frequency signal 16 into a radio frequency signal 19.

The frequency hopping pattern used for this transmission has the same frequency band and period as the hopping pattern for reception, and the hopping pattern for reception is
Although synchronized with the pattern, however, the same frequency is set so that transmission and reception do not overlap at the same time, and by doing so, bidirectional communication is enabled.

In the transmission / reception apparatus of FIG. 1, the hopping pattern 18 for transmission is generated by delaying the hopping pattern 6 for reception by several hops by the delay circuit 20. FIG. 2 shows hopping patterns in transmission and reception used in the first embodiment, and the hopping pattern at the time of transmission is delayed by two hops from the hopping pattern at the time of reception.

The hopping signal is supplied to the level control circuit.
Enter in 21.

On the other hand, the level estimation circuit 24 estimates the channel status (propagation status) for each transmission hopping frequency using the received power level for each hop obtained by the level detection circuit 12,
The result is output to the level control circuit 21. The level control circuit 21 controls the transmission power level of the transmission signal 19 after hopping so that the reception side can obtain a predetermined reception power level even under the line condition estimated by the level estimation circuit 24. The signal whose transmission power is controlled is transmitted from the antenna 23 through the BPF 22.

A method of controlling the transmission power at this time will be described with reference to FIG. In FIG. 2, T represents the cycle of the hopping pattern. Level detection circuit 12
Detects the level of received power for each hop. Now, assuming that the level detection circuit 12 detects the received power level in the carrier wave of the frequency f3 at the first hop of T1 from the received signal 8 converted into the intermediate frequency, the information is transmitted to the level estimation circuit 24, and the level estimation circuit 24 estimates the level. Based on this information, the circuit 24 estimates the reception power level at the reception side when transmitting using the carrier frequency f3 for the next time.

The level control circuit 21 transmits a signal using the carrier frequency f3 at the third hop of T1. At this time, if the received power level estimated by the level estimation circuit 24 is small, it is set to a predetermined level. The transmission power level is controlled so that it can be increased to the reception power level.

Similarly, the transmission power level when transmitting a signal at the carrier frequency f4 at the fourth hop of T1 is T
It is determined based on the reception power level of the signal received at the second hop of No. 1, and the transmission power level when transmitting the signal at the carrier frequency f1 at the first hop of T2 is the same as that of the signal received at the third hop of T1. It is determined based on the received power level. Transmission power control for each hop is performed by repeating such a procedure.

FIG. 3 shows another example of the hopping pattern for transmission and reception. The hopping pattern for transmission is delayed by one hop from the hopping pattern for reception. Therefore, the mobile station
The reception power level of the receiving side in the transmission using the same carrier f1 of the second hop of T1 is estimated by the reception power level of the carrier f1 of the first hop of Determine the power level. Similarly, the transmission power level at the third hop of T1 is determined based on the reception power level at the second hop of T1.
The transmission power level at the fourth hop of T1 is determined by the reception power level at the third hop of
Transmit power control is performed.

If the hopping speed is faster than the transmission power control processing cycle or if the fading fluctuation is slow, the information on the reception power level at the first hop of T1 is transmitted to the second hop of T2 for transmission. It is also possible to utilize the information obtained from the received power level at the time of transmission using the next next same carrier frequency, such as being used for eye transmission power control.

(Second Embodiment) In the second embodiment, transmission power control will be described when the apparatus of FIG. 1 is used to perform transmission / reception by the low-speed frequency hopping / spread spectrum method in which the hopping frequency is switched at a low speed. In this method, a large number of symbols (N symbols) are transmitted during one hop, and the carrier frequency is hopped each time N symbols are transmitted.

FIG. 4 is a diagram showing the relationship between transmission and reception by paying attention to one carrier frequency f of the hopping frequencies. The mobile station transmits the signal of the carrier frequency f at times T0 to T1. Upon reception, at the next times T1 and T2, transmission is performed using the same carrier frequency f, which corresponds to the hopping pattern shown in FIG.

The transmitter / receiver firstly desires the desired reception power level 61 for reception and the optimum transmission power level (this is referred to as reference transmission power) capable of giving the desired reception power level to the reception side under good line conditions. ) Set 64 and.

Next, in the mobile station, the level detection circuit 12 detects the reception power level 60 at times T0 to T1 for each symbol, and the level estimation circuit 24 detects the average reception level of the last n symbols (n <N). Ask for 65. Then, the average reception level 65 of the n symbols is set as the estimated reception level 62 at times T1 and T2.

When the estimated reception level 62 is smaller than the desired reception power level 61 by d, it is judged that the line condition is bad, and the level control circuit 21 determines the reference transmission power 64 from the transmission power at times T1 and T2. It is set larger by d'and transmitted. This d'is the amount of transmission power required to raise the reception power level by d. Therefore, time T
As long as the channel condition does not change significantly between 1 and T2, the transmission power of the mobile station is increased, so that the reception power level of the base station can maintain the desired reception power level 61.

As described above, in the transmitter / receiver of the second embodiment, the received power level at time T1 to T2 is estimated from the average value of the received power levels of the last n symbols of the symbols received at time T0 to T1. . Therefore, by properly setting the width n for averaging, it is possible to perform estimation without the influence of noise. Moreover, since the latest information indicating the line status is used for the estimation, highly accurate transmission power control is performed.

(Third Embodiment) In the third embodiment, the method of estimating the received power level is carried out by a method different from that of the second embodiment in the transmission / reception using the low frequency frequency hopping / spread spectrum method.

FIG. 5 shows the transmission / reception relationship corresponding to FIG. As in the case of the second embodiment, the transmitter / receiver first sets the desired received power level 61 and the reference transmission power 64.

The mobile station detects the received power level 60 for each symbol at times T0 to T1 and obtains a moving average 66 of n symbols. By taking the moving average like this,
It is possible to capture a gradual change in which the influence of noise on the received power level is removed.

Next, from this moving average 66, time T1 to T2
The estimated received power level 62 at is calculated. The estimated received power level 62 is the level at time T1 from time T0 to T1.
It is estimated that the change amount (Δd / Δt) has the same value as the change amount of the moving average 66 in the last n symbols.

Then, the value of the time T1 at the estimated received power level 62 is smaller than the desired received power level 61 by d,
When the amount of change is Δd / Δt, the times T1 to T2
The transmission power 63 is set to a value whose initial value is larger than the reference transmission power 64 by d ′ and has a change amount of Δd ′ / Δt. This d'is the amount of transmission power required to increase the reception power level by d, and Δd '/ Δt is the transmission power required to change the reception power level at the rate of -Δd / Δt. It is the amount of change in power.

As described above, in the third embodiment, the times T0 to T0.
From the received power level at T1, the received power level at times T1 and T2 and its variation are estimated, and transmission power control is performed to compensate for them. Therefore, it is possible to control the transmission power with high accuracy, and it is possible to maintain the transmission / reception quality in a good state.

(Fourth Embodiment) In the fourth embodiment, the method of estimating the received power level in the third embodiment is modified in consideration of the variation pattern of the received electric field level due to the actual fading.

As shown in FIG. 7, the instantaneous value of the received electric field level due to actual fading shows a sharp drop from a state of gradual decrease, and tends to increase again. In transmission power control, it is difficult to estimate when such a sudden drop in the received power level occurs, but the amount of change in the moving average of n symbols of the received power level tends to decrease. In this case, from the viewpoint of the variation pattern of the reception electric field level, it is expected that the reception power level will drop sharply thereafter and the reception power level will continue to increase rapidly.

Therefore, when the amount of change in the moving average shows a decreasing tendency, it is necessary to estimate the subsequent received power level in consideration of these points.

In the fourth embodiment, as shown in FIG. 6, when the moving average 66 of the received power levels at times T0 to T1 is increasing, the times T1 to T are the same as in the third embodiment.
In the estimated received power level 62 in 2, the value at time T1 is the value of the moving average 66 of the last n symbols at times T0 to T1, and the amount of change (Δd / Δt) is equal to the amount of change of the moving average 66. Estimate as a level with a value. Then, the transmission power 63 at the times T1 and T2 is level-adjusted to an amount necessary to match the estimated reception power level 62 with the desired reception power level.

On the other hand, when the moving average 66 of n symbols of the received power level at times T0 to T1 is decreasing,
The value at the time T1 is the estimated received power level 62 at the time T
Having a value of 66, the moving average of the last n symbols from 0 to T1,
It is estimated as a level that does not fluctuate over time. The transmission power 63 at times T1 and T2 is the estimated reception power level
Level 62 to the amount needed to raise it to the desired received power level.

Since such an estimation is made, the time T
Even if the actual received power level 67 drops sharply between 1 and T2, the estimated received power level 62 does not significantly deviate from the actual received power level 67.

If it is estimated that the estimated received power level at times T1 to T2 decreases by the same amount as the moving average 66 of the received power levels at times T0 to T1, the actual received power level between times T1 and T2 is reduced. When the received power level 67 drops sharply, the estimated received power level and the actual received power level 67 are significantly different from each other during the subsequent process of increasing the received power level, and the transmitted power is in the wrong direction. Will be adjusted to. According to the transmission power control of the fourth embodiment, such adjustment error can be avoided.

[0062]

As is apparent from the above description of the embodiments, in the transmitting / receiving apparatus of the present invention, the downlink from the base station to the mobile station and the uplink from the mobile station to the base station overlap at the same time. Since a hopping pattern that does not occur is selected and multiplexed in the same frequency band, the transmitter can know the line status from the received power of the received signal, and can perform high-speed and highly accurate transmit power control. You can

Further, since the reception power level at the receiving side at the time of transmission can be accurately estimated based on the actual reception power level, the accuracy of the transmission power control can be improved and high quality communication can be maintained. it can.

Also, unlike the TDD system, control such as switching for switching between transmission and reception is not required, so that the structure is simple.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a transmission / reception device according to an embodiment of the present invention,

FIG. 2 is an example of a hopping pattern used in the first embodiment of the present invention,

FIG. 3 is another example of a hopping pattern used in the first embodiment,

FIG. 4 is a diagram for explaining a transmission power control operation in the second embodiment of the present invention,

FIG. 5 is a diagram for explaining a transmission power control operation in the third embodiment of the present invention,

FIG. 6 is a diagram for explaining a transmission power control operation in the fourth embodiment of the present invention,

FIG. 7 is a diagram showing a change in electric field level due to fading,

FIG. 8 is a block diagram showing a configuration of a conventional transmission / reception device,

FIG. 9 is an example of a hopping pattern used in a conventional transceiver.

FIG. 10 is a diagram showing a transmission / reception relationship in a conventional TDD system.

[Explanation of symbols]

 1 Transceiver 2, 22, 40, 43 Bandpass filter 3, 44 Received signal 4, 45 Synchronous circuit 5, 37, 46 Frequency control circuit 6, 47 Receiving side hopping pattern 7, 17, 36, 48 Frequency synthesizer 8 , 49 Received intermediate frequency signal 9,50 Demodulator 10,51 Decoder 11,52 Received data 12 Level detection circuit 13,32 Transmitted data 14,33 Encoder 15,34 Modulator 16,35 Transmitted intermediate frequency signal 19,39 Transmit radio frequency signal 20 Delay circuit 21 Level control circuit 23, 41 Antenna 24 Level estimation circuit 31 Transmitter 42 Receiver

Claims (5)

[Claims] 1. A transmission / reception device for transmitting / receiving a signal by a frequency hopping spread spectrum method, wherein each hopping pattern used on the transmission side and the reception side is a frequency belonging to the same frequency band and both hoppings at the same time. -A pattern detection frequency is configured so that the frequencies do not overlap, and level detection means for detecting the received power level at each hopping frequency of the received signal, and for each hopping frequency by using the information detected by the level detection means A transmission / reception device, comprising: a level control means for controlling transmission power. 2. The transmitting / receiving apparatus according to claim 1, wherein the transmitting side delays the hopping pattern used by the receiving side by N hops (N is an integer) and uses the hopping pattern for the hopping pattern. 3. The level detecting means detects the received power level of each symbol within one hop, and the level control means carries out the transmission power control based on an average value of the received power levels of a fixed number of the symbols. The transmitter / receiver according to claim 1 or 2, wherein the transmitter / receiver is performed. 4. The level detecting means detects the received power level of each symbol within one hop, and the level control means obtains the received power level obtained from a moving average of the received power levels of a fixed number of the symbols. The transmission / reception apparatus according to claim 1 or 2, wherein transmission power control is performed based on the change amount and the change amount thereof. 5. The level control means decreases the transmission power level in transmission power control with time when the change amount increases, and keeps the transmission power level constant with time when the change amount decreases. The transmitting / receiving apparatus according to claim 4, which is held.