JPS619045A - Radio communication system - Google Patents

Abstract

PURPOSE:To prevent the reduction in the burst utilizing efficiency caused in use with a scanning beam antenna by transmitting always a frame synchronizing signal and a clock reproducing signal to plural stations to simplify the equipment in the plural stations. CONSTITUTION:A data signal is inputted to a terminal A and a frame synchronizing signal is inputted to a terminal B. A pulse speed of the frame synchronizing signal is slower than the pulse speed of a data signal and selected as a speed below one over several, for example. When a frame synchronizing signal is kept transmitted continuously for full time as the clock reproducing signal, the frame synchronizing signal is used as the clock reproducing signal and when the frame synchronizing signal is transmitted intermittently, the clock reproducing signal is added successively. Further, a narrow channel 13 has a large power per 1Hz because the band is narrow and even when the power is irradiated by a wide antenna beam with low directivity gain, the S/N equal to or over the broad band channel 14 is obtained when the beam is received by plural stations 2.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to point-to-multipoint wireless communication using a scanning beam antenna that covers a wide area. -7 frame synchronization, which is intended for improvement, is related to a wireless communication system in which clock recovery is easy.

[Prior art and problems]

FIG. 11 is a diagram showing the configuration of general point-to-multipoint wireless communication.

Conventionally, one station 1 and multiple stations 21 as shown in FIG.
In so-called point-to-multipoint TDMA1, line communication between The method of doing this was often adopted. 3 shows the beam shape of this antenna.

Since such antennas radiate radio waves over a wide range, their directional gain is low, so in order to obtain the required communication quality, multiple stations 2. ~27 antennas are required to have a large diameter, and high-performance communication equipment equipped with a light transmitter with high transmission power and a receiver with a low noise figure is required, which is economical and simple. It was not possible to configure a system that could be installed.

Therefore, as another example, in order to increase the directivity gain of the antenna of one station, there is a method of narrowing the beam width of the antenna and scanning at high speed to communicate with a plurality of stations. However, in this case, when focusing on one station among the plurality of stations, radio waves from one station can only be received during a certain specific time.

In other words, it can only receive bursts while the antenna beam is pointing in the direction of its own station, and in addition to the data signals that are transmitted for control purposes, each burst receives a frame synchronization signal called a preamble, Signals for line control, such as clock regeneration signals, must be added. The length of the signal for controlling these lines needs to be a certain length, which is determined by the circuit configuration and the time interval until the radio waves are restored again, regardless of the length of time that the radio waves are irradiated to the local station. be.

1″aab, ohof)Rf)7>ff″l? -A/
As
This has the disadvantage that the ratio of signals for line control to the arriving signals increases, and the efficiency of burst utilization decreases. In addition, since multiple stations must maintain a clock from the moment a radio wave is received from one station until the station itself sends out a radio wave, it is necessary to provide each station with a high-Q tank circuit or PLL circuit. This has the drawback of increasing the price of the device.

[Purpose of the invention]

In order to solve these drawbacks, the present invention uses a scanning beam antenna for data signals while constantly sending frame synchronization signals and clock recovery signals to a plurality of stations.

Hereinafter, its structure and operation will be described in detail with reference to the drawings of the embodiment.

〔Example〕

FIG. 2 is a block diagram showing the transmitting section of one station according to an embodiment of the present invention. In Fig. 2, 4 is a modulator, 5 is a filter, 6 is a semi-fixed phase shifter, 7 is a variable phase shifter, 8 is a total m#, 9 is a local oscillator, 10 is a frequency converter, and 11 is a power Amplifier 12 represents an array element.

A data signal is input to terminal A, and a frame synchronization signal is input to terminal B. Here, the pulse speed of the frame synchronization signal is selected to be slower than the pulse speed of the data signal, for example, a fraction of the speed or less. As the clock regeneration signal, if the frame synchronization signal is continuously sent all the time, the frame synchronization signal can be used as the clock regeneration signal. If the frame synchronization signal is sent intermittently, a clock recovery signal is added following it. The input from terminal A and the input from terminal B are each modulated by a modulator 4 to frequencies that differ by approximately half of the 1 tM line channel, and a filter 5 cuts off the excess band. The modulated frame synchronization signal is sent to a semi-fixed phase shifter 6.
With a wide beam width, 1lllr
It is converted to have an arcuate phase in the R phase, that is, in the 7th element.

On the other hand, the modulated data signal is converted by a variable phase shifter 7 into a phase relationship such that the phase on the array elements has a linear slope depending on the direction of the antenna beam at each instant. The antenna beam can be scanned by changing this phase relationship from time to time. Both signals modulated by the multiplexer 8 are combined, converted into a high frequency signal by a frequency converter 10 using a high frequency wave oscillated by a common local oscillator 9, amplified by a power amplifier 11, and then sent to an array element 12. radiated from.

It is also possible to use a reflector behind the array element 12.

Although the case where the array element 12 is used as a 7-aided array for the terminal A has been described above, a changeover switch can be used instead of the variable phase shifter 7, and the array element 12 can also be used as a switching array. *Also, between the filter 5 and the variable phase shifter 7 and between the filter 5 and the semi-fixed phase shift n6, or between the frequency converter 10 and the power amplifier 11
It is also possible to use a frequency converter between the two to create multiple intermediate frequency stages.

The spectrum of the radio waves transmitted in this way is as shown in FIG. That is, FIG. 3 is a diagram showing the transmission spectrum of one station, and as shown in the figure, a narrowband channel 13 for transmitting a frame synchronization signal and a wideband channel 14 for transmitting a data signal are on one radio channel. Adjacent. You are free to choose which one is the higher frequency.

Because the narrow band is narrow, the power per IHz can be increased in the narrowband channel, and even if it is radiated with a wide antenna beam with low directional gain, the signal-to-noise when received by multiple stations 2 is equal to or higher than that of the wideband channel. You can get the ratio.

FIG. 4 is a block diagram of the receivers of a plurality of stations that receive this, and shows up to the demodulation section, 15 is an antenna, 16 is a circulator, 17 is an RF filter, 18 is a local oscillator, 19 20 represents a frequency converter, 20 represents a filter, and 21. represents a demodulator.

A transmitter is connected to terminal C. From the radio waves received by the antenna, an RF filter 17 selects only the 1tfA line channel, which is frequency-converted to an intermediate frequency by a frequency converter 19. A zero-order filter 20 separates narrowband channels and wideband channels, and demodulates them. The signal is demodulated by the receiver 21. In this way, in this system, since the narrowband channel and the wideband channel are included in one radio channel, an expensive high frequency section can be shared. The circuit after filter 20 is the conventional 2
Although twice as many parts are required, this part is cheaper than the high frequency part, so it does not impair the economic efficiency of the device.

Figure 5 is a diagram showing signals received by multiple stations, (D)
, (E) respectively correspond to the terminal D%E in FIG. This figure shows how fast signals are received in bursts. Each of the multiple stations refers to the frame synchronization signal and learns the time slot of the burst to be transmitted to the predetermined station, so that it can receive the signal to the own station. can do.

Further, by referring to the frame synchronization signal, it is possible to know the predetermined time slots in which the own station is allowed to transmit, so that the own station can transmit.

In this case, the slow frame synchronization signal that is constantly received can be appropriately multiplied and used as a clock.

FIG. 6 shows another embodiment of the present invention, and is a block diagram of the transmitting section of one station. A semi-fixed phase shifter 6 and a variable phase shifter 7 are inserted at the output of the local oscillator 9. A frequency converter may be used between the filter 5 and the frequency converter 100 or between the multiplexer 8 and the power amplifier 11 to form a multi-stage configuration with different intermediate frequencies [L or above, intermediate frequency stages and local oscillator 89] The case in which a phase shifter is inserted into the output has been described in detail, but in principle, a phase shifter may be inserted in the high frequency stage and multiplexing may be performed at the high frequency stage. In that case, designing the multiplexer will be difficult, but it will be easier to design the multiplexer. Since the signal can be branched to each array element after the tLt conversion, only two frequency converters are required, and when the number of array elements is large, the number of frequency converters can be significantly reduced.

Also, if you are prepared to increase the number of antennas for one station, you can radiate narrowband channels and wideband channels from separate antennas.

The receiving system of one station and the transmitting system of multiple stations may be the same as conventional ones.

〔Effect of the invention〕

As explained above, according to the method of the present invention, even though a scanning beam antenna is used, 4
By constantly sending frame synchronization signals and clock recovery signals to multiple stations, the equipment for multiple stations can be simplified, and the efficiency of burst utilization, which occurs when scanning beam antennas are used, can be reduced. The decline can be prevented.

As a result, the use of radio waves is highly efficient, and economical points and
This is highly effective because it makes it possible to provide a two-to-multipoint communication system.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the configuration of general point-to-multipoint wireless communication, FIG. 2 is a block diagram showing the transmitting section of one station according to an embodiment of the present invention, and FIG. 4 is a block diagram of the receiving section of multiple stations, FIG. 5 is a diagram showing signals received by multiple stations, and FIG. 6 is a diagram of one of the other embodiments of the present invention. FIG. 3 is a block diagram of a transmitting section of the station. 1...One station, 2I-27...Multiple stations, 3...Beam shape of shaped beam antenna, 4...Modulator, 5... ·····filter,
6... Semi-fixed phase shifter, 7... Variable phase shifter, 8... Multiplexer, 9... Local oscillator, 10... ...Frequency converter 1, 11...
1A...Power amplifier, 12...
Array element, 13...Narrowband channel, 14
...Broadband channel, 15...Antenna, 16...Circulator, 17...
・RF filter, 18...Local oscillator, 19.
... Frequency converter, 20 ... Filter, 21 ... Demodulator, 22 ... Frame synchronization signal, 23 ... Data signal agent Patent Attorney Takashi Honma - Figure 1, Figure 2, Figure 3, Bunkyo, Figure 4, Figure 5, No'! -Stock Figure 6

Claims (4)

[Claims] (1) In a wireless communication system that transmits digital signals bidirectionally between one station and multiple stations, one wireless channel is divided into a narrowband channel that transmits a signal including a frame synchronization signal and a signal that includes a data signal. The narrowband channel uses an antenna that irradiates a communication target area where multiple stations exist with a fixed beam, while the wideband channel uses an antenna that scans the communication target area with a narrow beam. A wireless communication method characterized by performing TDMA communication. (2) One array antenna is shared between a narrowband channel and a wideband channel, and the phase of each array element is fixed for the narrowband channel, and the phase is changed using a phase shifter for the wideband channel, or multiple array antennas are used. The wireless communication system according to claim (1), wherein beam scanning is performed by switching elements. (3) A phase shifter for beam scanning of a wideband channel or a switch for beam scanning is provided in an intermediate frequency stage, and a frequency converter for a wideband channel and a narrowband channel is shared. The wireless communication method described in (2). (4) The wireless communication system according to claim (1) or (2), wherein a phase shifter for performing beam scanning of a wideband channel is provided at the output section of the local oscillator.