JP2001016163A - Device and system for radio transmission - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device and a system for radio transmission capable of high-speed transmission to a distant place even in an environment, where a delayed wave exists, and capable of transmitting/receiving a signal without trouble even in a system to proximately use radio transmission equipment. SOLUTION: This device is provided with plural means for transmitting data while using a low frequency band not to be affected by the delayed wave, a means for distributing data to be transmitted to plural data transmitting means and a means for merging plural pieces of transmitted data. Besides, a radio transmission equipment 10 to be master equipment has a means for receiving a broadcasting signal, a means for detecting the specified signal of the broadcasting signal and a means for synchronizing the transmission timing of the signal with the detected signal. Therefore, even when a transmission rate is accelerated, data can be transmitted to the distant place. Further, even in the radio transmission system to proximately use the radio transmission equipment, signals can be transmitted/received without trouble.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wireless transmission device and a wireless transmission system, and more particularly, to the presence of a delay wave, such as a wireless LAN in a building, data transmission between buildings, and a connection between a telephone pole and a device in a home. The present invention relates to a wireless transmission device and a wireless transmission system that are used in an environment or where a number of wireless transmission devices are used in close proximity.

[0002]

2. Description of the Related Art Conventionally, as a wireless transmission device for data used in an environment where a delay wave exists, such as a wireless LAN in a building, data transmission between buildings, connection between a telephone pole and a device in a house, etc. And the diversity transmission / reception system and the use of an equalizer. Also, in a wireless transmission system in which a large number of wireless transmission devices are used in close proximity, measures have been taken, such as using different channels in adjacent wireless transmission devices.

[0003]

In recent years, there has been a strong demand to increase the transmission speed of wireless data transmission, and accordingly, for example, the data transmission speed of a wireless LAN has tended to be increased from 10 Mbps to 40 Mbps. is there.
However, the following problems occur with the increase in speed. FIG. 5 is an example of measurement data showing an increase in the error rate depending on the distance of the wireless data transmission device when the antenna diversity scheme is adopted. FIG. 5A shows that the transmission speed is 10 Mb.
ps, (b) shows the case of 5 Mbps, and (c) shows the case of 2 Mbps. As is apparent from this figure, when the data transmission speed is increased, there is a problem that the distance that can be transmitted with the same error rate becomes shorter. The cause is considered to be mainly the influence of a delayed wave (a reflected wave from a wall or the like).

FIG. 4 is an explanatory diagram showing the effect of a delayed wave. FIG. 4A shows the relationship between the direct wave A and the delayed wave B at a low speed. Note that the vertical dotted lines indicate the boundaries of the modulation section T (modulation unit). In FIG. 4A,
The delayed wave B has substantially no effect on the next modulation section.

FIG. 4B shows a quadruple data transmission rate (modulation unit T is １ ／) under the same environment as FIG. 4A.
2 shows the effect of a delayed wave when transmission is performed at a high speed. In this case, the delayed wave B overlaps and affects the next modulation section, and the data error rate increases. For example, 4
If 10 Mbps data transmission is performed with phase PSK, 1
The time of the modulation section is 200 nanoseconds. Therefore, if the delay time of the delayed wave is 200 nanoseconds, the delayed wave is received overlapping the next modulation section and the data error rate increases, but the time difference between the direct wave and the delayed wave is 200 nanoseconds. For this to occur, the propagation distance difference between the direct wave and the delayed wave needs to be 60 meters. However, in an actual use environment such as in a building, there is little possibility that such a delayed wave having a large delay time is generated.

However, when the transmission rate is increased to 40 Mbps, which is quadrupled, the length of one modulation section becomes 50 nanoseconds, and the propagation distance difference between the corresponding direct wave and the delayed wave becomes 15 meters. In an actual use environment, there is a problem that the possibility of the occurrence of such a delayed wave due to reflection from a wall or the like increases. Further, when the transmission speed is increased, the frequency band of the transmission wave is also widened. However, when the frequency band is widened, the effect of frequency fading due to multipath is strongly affected, and there is a problem that the error rate increases.

In a wireless transmission system in which a large number of wireless transmission devices are used in close proximity, even if the channels used in the adjacent wireless transmission devices are different, for example, one of the wireless transmission devices transmits on a certain channel. When the other wireless transmission device in proximity attempts to receive on an adjacent channel, the interference wave component of the transmission wave of one device (unnecessary wave component spreading in the frequency bands on both sides of the transmission wave) is at a high level and the other device is There is a problem that the reception cannot be performed even on the channel to be received.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art, to enable high-speed transmission without reducing the transmission distance even in an environment where a delayed wave exists. It is an object of the present invention to provide a wireless transmission device and a wireless transmission system that can transmit and receive signals without difficulty even in a wireless transmission system in which the wireless transmission device is used in close proximity.

[0009]

SUMMARY OF THE INVENTION The present invention relates to a radio transmission apparatus used in an environment where a delay wave exists, and a plurality of data transmission systems using a low frequency band which is substantially unaffected by the delay wave. Data transmission means, data distribution means for distributing data to be transmitted to the plurality of data transmission means, and data integration means for integrating data transmitted by the plurality of data transmission means. I do. In a wireless transmission system including a plurality of wireless transmission units serving as a master unit for controlling signal transmission timing, a synchronization unit for synchronizing the signal transmission timing of the wireless transmission unit is provided.

According to the present invention, high-speed transmission is performed using a plurality of low-speed transmission channels that are less affected by delay waves, so that even if the transmission speed is increased, the transmission distance is reduced due to the effects of delay waves. Data transmission to a distant place. Further, even in a wireless transmission system in which a large number of wireless transmission devices are used in close proximity, transmission and reception of signals can be performed without any trouble.

[0011]

Embodiments of the present invention will be described below in detail. FIG. 1 is a block diagram illustrating a configuration of a first embodiment of a communication system including a wireless transmission device to which the present invention has been applied. The wireless transmission device 10 is connected to a plurality of terminals 12 and 13 via a bus-type LAN 11 and to other wireless transmission devices 14 and 15 via a wireless transmission path.

The LAN controller 2 of the wireless transmission device 10
Numeral 0 has a function of interfacing signals with the well-known bus-type LAN 11, receives data (LAN packets) addressed to terminals connected to the other wireless transmission devices 14 and 15, and outputs the data to the main controller 21. At the same time, data (LAN packets) addressed to the terminals 12 and 13 received from the main controller 21 is transmitted to the LAN 11.

The main controller 21 executes a transmission control function including a CPU, a RAM used as a buffer and a work area, a ROM storing a transmission control program, and the like. That is, the LAN packet received from the LAN controller 20 is assigned to each of the transmission / reception controllers (one of 22 to 25) which is currently empty or has the least amount of data waiting to be transmitted in packet units.

Further, a synchronization signal for determining the transmission timing is generated to synchronize the transmission operation of each channel. As shown in FIG. 1, when the three wireless transmission devices 10, 14, and 15 perform communication, for example, tokens are sequentially transferred between the wireless transmission devices. Then, the wireless transmission device that has received the token generates a synchronization signal, transmits data waiting for transmission in all channels, and when the transmission is completed, transfers the token to the next wireless transmission device.

Each of the transmission / reception controllers 22 to 25 corresponds to each of the radio channels ch1 to ch4, and generates a packet by adding a header or an error check code to data (LAN packet) allocated from the main controller 21. Transmitter / receiver circuits 26-2 corresponding to channels
9 is output.

The transmission / reception circuits 26 to 29 incorporate a transmission circuit and a reception circuit, and the transmission circuit modulates a carrier based on input data, converts the carrier to a predetermined frequency band, amplifies and outputs. The modulation method is arbitrary such as QAM, and the band is also arbitrary. Further, a spread spectrum method may be adopted. The transmission signal is transmitted from the antenna 34 via the attenuators ATT30 to ATT33.

The receiving circuits of the transmission / reception circuits 26 to 29 demodulate, decode and output the signals received from the antenna 15 to the transmission / reception controllers 22 to 25. Although the transmission circuit and the reception circuit are connected via the attenuator ATT, there is no problem because the transmission power is as small as several milliwatts and half-duplex communication for alternately performing transmission and reception is performed.

The transmission / reception controllers 22 to 25 store the received data, perform processing such as error correction, and perform LA processing.
The N packets are reproduced and output to the main controller 21. The LAN packet output to the main controller 21 is further transferred to the LAN controller 20 and the LAN 1
1 is sent. When large data such as a file is divided into a predetermined amount and transferred through a plurality of channels, a serial number or the like is assigned to the divided data, and the file is reproduced in the receiving main controller in the order of the serial number. I do.

If an error is detected in the received data,
Each of the transmission / reception controllers 22 to 25 transmits a retransmission request packet to the partner device, and the transmission / reception controller of the partner device that has received the retransmission request packet retransmits the stored transmission packet. If the retransmission control is repeated many times, since the response packet is not returned, the same packet may be retransmitted from the data transmission source terminal and may be duplicated. Therefore, the number of retransmissions is set to several times.

FIG. 2 is an explanatory diagram showing a frequency band used by the wireless transmission device according to the first embodiment of the present invention. As a frequency band to be used, for example, a 2.4 GHz band is used.
For example, about 20 MHz as a band per one channel, and 80 as a frequency band of a total of four channels, for example.
Use about MHz.

FIG. 3 is an explanatory diagram showing transmission and reception timings in the wireless transmission apparatus according to the first embodiment of the present invention. A synchronization signal as shown in FIG. 3 is output from the main controller 21 to each of the transmission / reception controllers 22 to 25. Each of the transmission / reception controllers 22 to 25 operates a transmission circuit in the transmission / reception circuit in synchronization with the synchronization signal. And send the data. Therefore, the transmission / reception circuits of the four channels repeat transmission and reception synchronously.

This is because the frequencies of the respective channels are close to each other, so that if one high-frequency filter is not used, another channel cannot receive a signal when one channel transmits. With the above-described configuration, even if the transmission speed is increased, the transmission distance does not decrease and transmission can be performed to a distant place.

Next, a second embodiment will be described. In the first embodiment, four signal transmission / reception devices are mounted in one wireless transmission device, and the operations of the respective signal transmission / reception devices are synchronized in order to perform transmission / reception without hindrance. This also occurs when the wireless transmission devices are arranged close to each other. FIG. 6 is a block diagram illustrating a configuration example of a wireless transmission system according to a second embodiment of the present invention, in which a plurality of wireless transmission devices are arranged in close proximity. The group A40 and the group B50 perform data transmission independently. A terminal device 44 is connected to the parent device 41 of the group A 40, and performs data transmission with the child devices 42 and 43 in the group by, for example, a polling method. Similarly, the group B also performs data transmission. A terminal (not shown) is also connected to the slave unit.

Here, for example, the slave unit 43 of the group A 40
When the slaves 52 of the group B50 and the slaves 52 of the group B50 are arranged close to each other, reception of the other may not be possible due to the respective transmission waves. In the present invention, the above-mentioned problem is solved by synchronizing the transmission timings of the master units 41 and 51 that manage the transmission timings of the slave units in each group.

As a synchronization method, for example, if all the master units are L
When connected by a transmission path such as an AN, transmission can be synchronized by broadcasting a signal for transmission synchronization. However, in order to synchronize transmissions between master units that are not connected by a transmission line, such as transmission between buildings or transmission between an electric pole and a device at home, a device is required. In the present invention, each base unit receives an existing or newly provided broadcast signal, detects a specific signal in the broadcast signal, and synchronizes transmission at the detection timing.

FIG. 7 is a block diagram showing a configuration of a wireless transmission apparatus (master unit) according to a second embodiment of the present invention. The LAN controller 61 of the wireless transmission device 41 serving as a master unit has a well-known bus-type LAN interface function, receives a LAN packet, outputs the received LAN packet to the main controller 62, and outputs the terminal 44 received from the main controller 62.
Send the LAN packet addressed to it.

The main controller 62 executes a transmission control function including a CPU, a RAM used as a buffer and a work area, a ROM storing a transmission control program, a timer circuit operated by a clock signal, and the like. That is, it outputs the LAN packet received from the LAN controller 61 to the transmission / reception controller 63, generates a synchronization signal for determining the transmission timing, and outputs the synchronization signal to the transmission / reception controller 63.

The transmission / reception controller 63 generates a wireless packet by adding a header or an error check code to the LAN packet, and outputs the wireless packet to the transmission / reception circuit 64 in synchronization with the synchronization signal. The transmission / reception circuit 64 includes a transmission circuit and a reception circuit, and the transmission circuit modulates a carrier based on input data, converts the carrier to a predetermined frequency band, amplifies and outputs.
The modulation method is arbitrary such as QAM, and the band is also arbitrary.
Further, a spread spectrum method may be adopted. The transmission signal is transmitted from the antenna 66 via the antenna switch 65.

The reception circuit of the transmission / reception circuit 64 includes an antenna 6
6 and a signal received via the antenna switch 65 are demodulated, decoded, and output to the transmission / reception controller 63. The transmission / reception controller 63 accumulates the received data,
Perform processing such as error correction to reproduce LAN packets,
Output to the main controller 62.

LA output to main controller 62
The N packet is further transferred to the LAN controller 61,
Sent to terminal 44. When an error is detected in the received data, the transmission / reception controller 63 transmits a retransmission request packet to the partner device, and the transmission / reception controller of the partner device that has received the retransmission request packet retransmits the stored transmission packet.

The broadcast receiving circuit 68 includes a broadcast receiving antenna 67.
Is a well-known circuit that receives, for example, a broadcast signal of a television broadcast and outputs an NTSC video signal. The vertical synchronization signal separation circuit 69 is a known circuit that separates a vertical synchronization signal from an NTSC video signal and outputs the separated signal.
In the case of the NTSC system, since one second includes 60 vertical synchronization signals, the period of the vertical synchronization signal is about 16.7 milliseconds. The main controller 62 activates an interrupt process according to the output signal of the vertical synchronization signal separation circuit 69, and synchronizes the generation timing of the synchronization signal with the vertical synchronization signal of the broadcast signal.

FIG. 8 is an explanatory diagram showing the synchronization operation in the wireless transmission device (master unit) according to the second embodiment of the present invention. FIG.
(A) shows the transmission timing of the master unit and the slave unit at the time of polling. The master unit 41 transmits, for example, 0.5 milliseconds every time the master timer set to 1 millisecond expires. Then, the polled slave uses the slave timer to start transmission 0.5 ms after the start of transmission of the master. Note that a non-transmission time (guard time) of a predetermined period is provided between each transmission end timing and the transmission start timing of the next station.

FIG. 8B shows a case where an interrupt signal is output from the vertical synchronizing signal separating circuit 69 to the main controller 62 of FIG. 7 during transmission of the slave unit. In this case, the main controller 62 of the master unit restarts the timer of the master unit being timed by the interrupt signal. Therefore,
If the set time of the master unit timer is 1 millisecond, the transmission start timing of the next master unit is 1 millisecond after the interruption.

FIG. 8C shows a case where an interrupt signal is output from the vertical synchronizing signal separating circuit 69 to the main controller 62 during transmission from the master unit. Again, in this case,
Since the main controller 62 of the base unit restarts the base unit timer in response to the interrupt signal, if the set time of the base unit timer is 1 millisecond, the transmission start timing of the next base unit is 1 millisecond from the interrupt. Later. Since the operation becomes unstable if the transmission start of the master unit and the interrupt timing overlap, the interrupt cycle should not be an integral multiple of the transmission cycle.

The existing broadcast signals that can be used include a specific frequency band that is separated from the frequency band used for data transmission, can be easily received anywhere, and can be detected in a relatively short period, for example, a few seconds or less. Signals containing signals are preferable. For example, standard radio waves such as JJY, terrestrial or satellite broadcast television broadcast waves, AM (medium wave) or FM (ultra short wave) radio broadcast waves (text broadcast signals), P
A mobile phone base station signal including an HS and a pager, a GPS signal, a position detection signal such as Loran, and the like can be considered. As a specific signal to be detected, in addition to a vertical synchronization signal, a tone signal of a predetermined frequency, a station identification signal in a digital signal,
It may be a synchronization signal, a time signal, or the like. If the detection cycle of the specific signal is too short, the interrupt cycle may be multiplied by an integer using a counter or the like.

When a broadcast signal cannot be received indoors or the like, a synchronization signal broadcasting station dedicated to the wireless transmission system may be provided to broadcast the synchronization signal. Further, when a commercial power supply is used as the power supply, the zero-cross timing of the commercial power supply may be detected and used as an interrupt signal. With the above configuration and operation, the phases of the base unit timers that control the transmission periods of the base units in each group can be made uniform, and the transmission timing of each slave station determined by the transmission timing of the base unit also matches.

FIG. 9 is an explanatory diagram showing the configuration of the wireless transmission system according to the third embodiment of the present invention. In the second embodiment, a configuration is disclosed in which a broadcast signal receiving circuit is provided in all master units to achieve synchronization, but in the third embodiment, a plurality of master units are grouped for each region, and one master is provided for each group. Independent master 70,
71, and other master units 80 to 85, 9 in the group.
0 to 95 operate so as to synchronize with the independent master unit.

In FIG. 9, one independent master 70 and a plurality of slaves 80 to 85 form one group, and another independent master 71 and a plurality of slaves 9
0 to 95 form another group. A circular area around each master unit is a service area of each master unit, in which slave units (not shown) are scattered. The independent parent devices 70 and 71
It has the configuration of FIG. 7 disclosed in the second embodiment, and performs transmission independently and in synchronization with a broadcast signal, as in the second embodiment.

The slave master units 80 to 85 are obtained by removing the broadcast receiving antenna 67, the broadcast receiving circuit 68, and the vertical synchronizing signal separating circuit 69 from the configuration of FIG. 7, for example. However, the dependent master units 80 to 85 can receive the transmission signal of the independent master unit 70 using the transmission / reception circuit 64. Therefore, data transmission is performed in synchronization with the received transmission signal of the independent master device 70.

FIG. 10 is an explanatory diagram showing the synchronization operation in the wireless transmission system according to the third embodiment of the present invention. The subordinate base unit periodically receives the transmission signal of the independent main unit. Until the start of signal transmission by the independent master unit is recognized by the main controller 62 of the slave master unit, there is a detection delay such as a transmission delay and a delay caused by the receiving circuit. Therefore, the dependent master sets the synchronization timer when the signal is detected by the independent master, and sets a value obtained by subtracting the detection delay as the set value. As the detection delay value, for example, a fixed value obtained as a result of an experiment may be set in advance. By this processing, the transmission timings of the next independent master device and the slave master device coincide with each other. The second and subsequent transmission cycles are set to the same predetermined values.

With the above configuration and operation, the independent master unit is synchronized with the broadcast signal, the dependent master unit is synchronized with the independent master unit, and the slave units are synchronized with the master unit. The timing can be controlled. Note that the dependent master unit may be synchronized with the master unit having the highest received signal strength instead of the independent master unit.

While the embodiment of the present invention has been disclosed above, the present invention may have the following modifications. In the embodiment, an example in which three or more wireless transmission apparatuses transfer LAN packets is disclosed. However, the system configuration may be a one-to-one configuration in which two wireless transmission apparatuses transmit and receive data. Control method is C in addition to token passing
Any method such as SMA and TDMA can be adopted. Further, a system may be used in which data such as an arbitrary file is transferred as data in a predetermined amount and the file is reproduced again on the receiving side. The size of the packet exchanged between the transmission / reception controllers is also arbitrary. In the embodiment, the example in which the number of channels is four is disclosed, but the number of channels can be arbitrarily set to two or more.

When the transmission power is increased, the transmission circuit and the reception circuit may be separated by using a directional coupler such as a circulator or an electronic switch circuit. If the frequencies of the channels are distant from each other and can be separated by a filter or the like, the configuration may be such that each transmitter transmits asynchronously. In the embodiment, an example in which FDM is adopted as the multiplexing method is disclosed. However, as the multiplexing method, a multiplexing method such as CDM and wavelength multiplexing using infrared rays can be adopted in addition to FDM.

[0044]

As described above, in the present invention,
In a wireless transmission device used in an environment where a delayed wave exists, a plurality of data transmitting means for transmitting data using a low frequency band substantially unaffected by the delayed wave, and a plurality of data transmitting means for transmitting data to the plurality of data transmitting means. Data distribution means for distributing data to be transmitted and data integration means for integrating data transmitted by a plurality of data transmission means, so that even if the transmission speed is increased, the transmission distance is reduced due to the influence of delay waves. Without this, there is an effect that data transmission can be performed far away. Further, in a wireless transmission system including a plurality of wireless transmission means serving as a master unit for controlling signal transmission timing, since a synchronization means for synchronizing the signal transmission timing of the wireless transmission means is provided, a large number of wireless transmission devices are close to each other. There is also an effect that the transmission and reception of signals can be performed without hindrance even in a wireless transmission system that is used in a mobile communication system.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a first embodiment of a communication system according to the present invention.

FIG. 2 is an explanatory diagram showing a frequency band used in the first embodiment.

FIG. 3 is an explanatory diagram showing transmission and reception timings in the first embodiment.

FIG. 4 is an explanatory diagram showing the influence of a delayed wave.

FIG. 5 is a graph of measured data showing an increase in error rate with distance.

FIG. 6 is a block diagram illustrating a configuration example of a wireless transmission system according to a second embodiment.

FIG. 7 is a block diagram illustrating a configuration of a master unit according to a second embodiment.

FIG. 8 is an explanatory diagram showing a synchronous operation in the master unit of the second embodiment.

FIG. 9 is an explanatory diagram illustrating a configuration of a wireless transmission system according to a third embodiment.

FIG. 10 is an explanatory diagram showing a synchronous operation in the third embodiment.

[Explanation of symbols]

10: wireless transmission device, 11: bus type LAN, 12, 1
3 ... terminal, 14, 15 ... wireless transmission device, 20, 61 ... L
AN controller, 21, 62 ... main controller,
22-25, 63 ... transmission / reception controller, 26-29,
64 transmission / reception circuit, 30-33, 65 antenna switch, 34, 66, 67 antenna, 40, 50 group, 41, 51 master unit, 42, 43, 52, 53 slave unit, 44 terminal 68, a broadcast receiving circuit, 69, a vertical synchronizing signal separating circuit, 70, 71, independent master units, 80 to 85, 9
0 to 95: slave unit

Claims (5)

[Claims] A wireless transmission device used in an environment where a delay wave exists, a plurality of data transmission means for transmitting data using a low frequency band which is substantially unaffected by the delay wave, A wireless transmission apparatus comprising: a data distribution unit that distributes data to be transmitted to the plurality of data transmission units; and a data integration unit that integrates data transmitted by the plurality of data transmission units. 2. The radio transmission apparatus according to claim 1, wherein said data transmission means includes a data error detection means and a data retransmission means. 3. A wireless transmission system including a plurality of wireless transmission means serving as a master unit for controlling signal transmission timing, comprising: synchronization means for synchronizing signal transmission timing of said wireless transmission means. system. 4. The synchronizing means includes: a receiving means for receiving a broadcast signal; a signal detecting means for detecting a specific signal of the received broadcast signal; and a transmission timing of a signal transmitted from a wireless transmission means. 4. The wireless transmission system according to claim 3, further comprising: a broadcast synchronizing unit that synchronizes with a synchronized signal. 5. The broadcast signal includes a standard radio wave, a television broadcast radio wave, a radio broadcast radio wave, a base station signal for a mobile phone,
The radio transmission system according to claim 3, wherein the radio transmission system is one of a PS signal and a synchronization signal broadcast wave dedicated to the radio transmission system.