JPH09200086A - Wireless communication system - Google Patents

Abstract

(57) Abstract: When a specific frequency channel used for a frequency hopping pattern has a lot of noise, erroneous data is received. SOLUTION: The radio wave environment (reception level) of a usable channel among a plurality of frequency channels is measured, and the reception level is low based on the measured radio wave environment for these usable frequency channels. The order is given from. The receiving side is notified of this order, and frequency hopping is performed according to this order for reception. On the other hand, the transmission side performs transmission by frequency hopping according to the notified order.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wireless communication system for performing communication between a plurality of wireless communication terminals by a frequency hopping method.

[0002]

2. Description of the Related Art In recent years, wireless communication has rapidly progressed and has been used in various fields. In particular, digital wireless communication systems are being put to practical use, and the spread spectrum communication is receiving particular attention among them. This spread spectrum communication is known as a method that spreads information to be transmitted over a wide band, has a high interference removal capability, and enables communication with excellent confidentiality. 2.4GH around the world
The z-band frequency is allocated for spread spectrum communication, and its spread is progressing all over the world.

Spread spectrum communication systems are roughly classified into frequency hopping (FH system) and direct spread (DS system). The former performs transmission using a wide band by changing the modulation frequency within a fixed time, and the latter spread-modulates the information to be transmitted with a pseudo-noise code at a speed that is ten to several hundred times that speed. By doing so, a wider band is used.

Of these, a system using frequency hopping has already been developed because it can be realized with a relatively simple circuit configuration. In order to perform communication by the frequency hopping system, it is necessary that the frequency hopping pattern of the transmission side terminal and that of the reception side terminal are the same and that the frequency switching is synchronized.

[0005]

However, in the communication by the above-mentioned frequency hopping method, even if the frequency hopping patterns of the transmitting terminal and the receiving terminal are the same and the frequency switching is synchronized, it is used for the frequency hopping pattern. When a specific frequency channel among the frequency channels to be used has a lot of noise, for example, there is a problem that erroneous data is received when transmitting and receiving using the specific frequency channel.

Further, in the wireless communication system adopting the above-mentioned method, there are problems that the confidentiality of the wireless communication is lowered and the noise is increased.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a wireless communication system capable of avoiding reception of erroneous data.

In order to achieve the above object, the present invention provides a plurality of radio communication devices that perform spectrum spreading by frequency hopping according to a predetermined hopping pattern and perform transmission / reception on a plurality of frequency channels. In the wireless communication system, the means for measuring the radio environment of a usable channel among the plurality of frequency channels; Means for giving the order, the means for notifying the receiving side of the order, the means for transmitting by frequency hopping according to the notified order, and the means for receiving by frequency hopping according to the notified order. With.

[0008]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. (System Configuration) FIG. 1 is a diagram showing a configuration of a wireless communication system according to an embodiment of the present invention. The system shown in the figure comprises a plurality of data terminal devices. The definition of the data terminal device here is “a terminal (data terminal) having a function of transmitting an arbitrary amount of data in a burst”, and the terminal device is not limited to the computer 101-A but the printer 101- B, copier 101-C, video conference terminal 101-D, facsimile 101-E, LAN
The bridge 101-F and other various terminals that perform data processing, such as an electronic camera, a video camera, and a scanner, which are not shown, are applicable.

A major feature of the present system is that these data terminals can freely communicate with each other.

The detailed configuration of the system and its operation will be described below. (Configuration of Data Communication Terminal) FIG. 2 is a block diagram showing an internal configuration of a data communication terminal that can be accommodated in the present system and a wireless adapter for connecting the data terminal. In the figure, 701 is a data terminal, 702 is a wireless adapter, and inside the wireless adapter 702, 703
Is a wireless unit. The data terminal 701 is the wireless adapter 7
02, for example, a personal computer, a workstation, a printer, a facsimile, and other data terminal equipment, which are connected via a communication cable or an internal bus.

Reference numeral 704 is a main control unit, for example,
CPU (central processing unit) and its interrupt control, DM
A peripheral device that performs A control and the like, an oscillator for a system clock, and the like, and controls each block in the wireless adapter 702. A memory 705 includes a ROM for storing the control program of the main control unit 704, a RAM used as a buffer area for various processes, and the like.

Reference numeral 706 denotes a communication i / f unit, which is a communication i / f that is standardly equipped with the data terminal equipment enumerated as the data terminal 701 as described above, for example, a communication i / f such as RS232C, Centronics, and LAN. Internal buses of personal computers and workstations (eg IS
A bus, PCMCIA i / f, etc.) are applicable. A terminal control unit 707 manages various communication controls required for data communication between the data terminal 701 and the wireless adapter 702 connected via the communication i / f 706.

Reference numeral 708 is a channel codec for performing frame processing and radio control, and its internal configuration will be described later. Here, the data assembled into a frame by the channel codec 708 is transmitted to the main device (not shown) or the opposite terminal via the radio unit 703. Also, 7
An error correction processing unit 09 is used to reduce bit errors occurring in data by wireless communication. At the time of transmission, an error correction code is inserted into the communication data, and at the time of reception, an error position and an error pattern are calculated by predetermined arithmetic processing, and the bit error in the received data is corrected. A timer 710 provides a timing signal used by each block inside the wireless adapter 702. (Structure of Radio Unit) FIG. 3 is a block diagram showing the structure of a radio unit commonly used by the main unit, wireless dedicated telephone, and data communication terminal of the present system. In the figure, 601a,
Reference numeral 601b is a transmitting / receiving antenna, and 602 is an antenna 60.
1a, 601b changeover switch, 603 is a band pass filter (hereinafter referred to as BPF) for removing signals in unnecessary bands, 604 is a transmission / reception changeover switch, 605 is a reception system amplifier, and 606 is a transmission system. Amplifier (with power control), 607 is 1st. IF
Is a down converter, and 608 is an up converter.

Further, 609 is a transmission / reception changeover switch, 610 is a BPF for removing a signal in an unnecessary band from the signal converted by the down converter 607, 6
11 is 2nd. This is a down converter for IF, and here, 1st. IF down converter 607, 2n
d. The IF down converter 611 constitutes a double-conversion reception mode.

612 is 2nd. BPF for IF, 613
Is a 90 ° phase shifter, 614 is a quadrature detector, and these BPF 612 and 90 ° phase shifter 613 detect and demodulate the received signal. Further, 615 is a waveform shaping comparator, 616 is a voltage control type oscillator (hereinafter referred to as VCO) of the receiving system, 617 is a low pass filter (hereinafter referred to as LPF), 618 is a programmable counter (not shown), A phase-locked loop (PLL) composed of a prescaler, a phase comparator, etc.
The O616, LPF617, and PLL618 form a frequency synthesizer for the receiving system.

Reference numeral 619 denotes a VCO for generating a carrier signal,
620 is an LPF, 621 is a programmable counter,
A PLL composed of a prescaler, a phase comparator, etc.
The VCO 619, LPF 620, and PLL 621 form a frequency synthesizer for hopping. Reference numeral 622 denotes a transmission system VCO having a modulation function, and 62.
3 is an LPF, 624 is a PLL including a programmable counter, a prescaler, a phase comparator, etc.,
The VCO 622, LPF 623, and PLL 624 constitute a transmission system frequency synthesizer having a frequency modulation function.

625 is the PLL 618,
Oscillator for generating reference clocks for 621, 624, 6
Reference numeral 26 is a band limiting filter (baseband filter) for the transmission data TxD (baseband signal).

Therefore, the operation of the radio section will be described below. <Operation During Transmission> Data (digital data) input from an external circuit such as a processor (not shown) is band-limited by the baseband filter 626 and then transmitted by the transmission system V.
It is input to the modulation terminal of CO622. This transmission system VCO
622 determines the frequency by the control voltage output from the transmission system PLL 624 and LPF 623, and generates the intermediate frequency (IF) modulated wave by direct modulation.

VCO 622, LPF 623, PLL 62
The intermediate frequency (IF) modulated wave generated by the frequency synthesizer configured in FIG.
Is input to the transmission system amplifier 606 after being added to the carrier signal generated by the frequency synthesizer including the VCO 619, the LPF 620, and the hopping PLL 621.

Then, the signal amplified by the transmission system amplifier 606 to a predetermined level has its unnecessary band signal removed by the BPF 603, and then emitted from the antenna 601 as a radio wave into space. <Operation During Reception> The signal received by the antenna 601 is amplified to a predetermined level by the reception system amplifier 605 after the unnecessary band signal is removed by the BPF 603. Then, the received signal amplified to a predetermined level is
The carrier signal is removed by down converter 607, and Ist. It is converted to a signal of IF frequency. This one
st. The received signal of the IF has the second band after the unnecessary band signal is removed by the BPF 610. The signal is input to the down converter 611 for IF.

2nd. Down converter 611 for IF
Is a VCO 616, LPF 617, receiving system PLL 618
And a signal generated by a frequency synthesizer composed of 1st. 2n depending on the IF input signal
d. A signal having an IF frequency is generated. And 2nd.
The received signal down-converted to the IF frequency is B
After the signal in the unnecessary band is removed by the PF 612, 9
It is input to the 0 ° phase shifter 613 and the quadrature detector 614.

The quadrature detector 614 performs detection and demodulation using the signal whose phase has been shifted by the 90 ° phase shifter 613 and the original signal. This quadrature detector 6
The data (analog data) demodulated by 14 is waveform-shaped by the comparator 615 as digital data RxD and output to an external circuit. (Explanation of Radio Frame) FIGS. 4 to 6 are views showing a radio frame configuration used in the present system.

In the present system, when a frequency hopping pattern is communicated, a "hopping pattern frame" (hereinafter referred to as HPF) frame is used, and when actual data is communicated, a "data frame" (hereinafter referred to as "frame") is used. A frame of DTF) is used. The details of the internal data of those frames will be described below.

FIG. 4 is a diagram showing the overall structure of the HPF. In the figure, FSYN is a synchronizing signal, HP1 to HP.
A frequency hopping frequency is stored in 26 every 5 ms, and the frequency hopping is performed by HP1 to HP26.

FIG. 5 is a diagram showing the overall structure of the DTF. In the figure, FSYN is a synchronization signal and DATA is
A data slot accommodating actual data, GT represents a guard time. Further, in FIG. 5, F9, F3,
F14 means the frequency used when wirelessly transmitting this frame.

FIG. 6 is a diagram showing the structure of an FSYN frame. In the figure, PR is a 62-bit preamplifier, SY, for frequency synchronization acquisition specified by the "Radio System Development Center (hereinafter referred to as RCR)"
N is a 31-bit frame synchronization signal specified by RCR, ID is a 63-bit calling signal specified by RCR, FI is a 2-bit channel type signal, and HPF, D
A signal for distinguishing TF, UW is a unique word (address of data terminal) including sub ID, and LC
CH indicates logical control information (including data length and data transmission end). (Description of Channel Codec) The above frame is processed by the channel codec described below.

FIG. 7 is a block diagram showing the internal structure of the channel codec 708 in the data communication terminal. In the channel codec 801, shown in the figure, 802 is a wireless unit, 803 is an ADP built into a wireless telephone, etc.
A CM codec 804 is a CPU of a wireless telephone or a wireless adapter.

In the channel codec 801, a radio control unit 805 controls the radio unit 802 to control transmission / reception switching and frequency hopping. The radio control unit 805 also has a function of performing carrier detection prior to data transmission. 806 is ADP
CM codec i / f, ADPCM codec 8
The serial data and the synchronous clock for exchanging the audio signal with the communication unit 03 are exchanged. Also, 807
Is a CPU i / f for exchanging control information with the CPU 804, and has a built-in register that stores the state and operation mode of each unit in the ASIC.

Reference numeral 808 denotes a transmission frame processing unit, which is an AD
A signal from the PCM codec 806 and logical control data input from the CPU 804 are assembled into a transmission frame. Reference numeral 809 denotes a received frame processing unit, which is a wireless unit 802.
Control information and voice data are extracted from the frame of the signal from the ADPCM codec i / f806 or CP.
Hand it over to Ui / f807. Further, reference numeral 810 is a synchronization processing unit composed of a DPLL, which reproduces a clock from a received signal and captures bit synchronization.

The basic operation of this ASIC will be described below. <Transmission Operation> At the time of transmission, the control information added to the transmission data frame is received from the CPU 804 at the CPU i / f 807. When this ASIC is used in a wireless-only telephone and a connection device in the main device, the transmission frame processing unit 8 together with the data from the ADPCM codec 803 is used.
At 08, a transmission frame is assembled. When the ASIC is used in the data terminal device, the transmission frame processing unit 80 is used together with the error correction coded burst data.
Assemble the transmission frame at 8.

When assembling the frame, the data is scrambled. This is necessary to maintain DC balance during wireless transmission. The radio control unit 805 takes the timing when the reception signal ends, and after carrier sense,
The wireless unit 802 is set to the transmission mode and the transmission frame is passed to the wireless unit 802. <Reception Operation> The wireless control unit 805 switches the wireless unit 802 to the reception mode when the data to be transmitted is completed,
Wait for the incoming frame. When the received frame is received, the data is descrambled, and then the control information and the data are extracted from the received frame. This control information is C
It is passed to the CPU 804 through the PU i / f 807.

When the received frame is the communication frame between the main unit and the wireless dedicated telephone (PCF) or the communication frame between the wireless dedicated telephones (PFF), the received data is passed to the ADPCM codec i / f 806 and transmitted. If the other party is a wireless-only telephone, it is output as voice through the ADPCM codec 803, but if it is the main device, it is sent to the communication path.

When the received frame is a burst data frame (BDF), the received data is transferred to the memory 705 in the data terminal device. (Description of Frequency Hopping Pattern) FIG. 8 is a diagram showing the concept of frequency hopping used in the present system.

In the system according to this embodiment, at present,
Twenty-six frequencies with a width of 1 MHz are used, which uses the band of 26 MHz that is approved for use in Japan. First, the transmitting terminal measures the radio wave environment of the 26 frequency channels one by one, assigns the order from the one having the lowest received level of the measured frequency channel, and sets the order as a frequency hopping pattern. (Description of Detailed Operation) The detailed operation of the transmitting side data terminal and the receiving side data terminal in the present embodiment will be described below.

FIG. 9 is a flowchart showing the operation of the transmitting side data terminal in this embodiment, and FIG. 10 is a flowchart showing the operation of the receiving side data terminal.

In this system, each data terminal is on standby in the frequency channel F1 (steps S401 and S501). First, when one data terminal transmits data to another terminal (step S
402: YES), the data terminal on the transmitting side (70 in FIG. 2)
1) transmits a transmission request command to the wireless adapter (702). The communication interface unit (706) that has received this transmission request command, the terminal control unit (70)
7) Notify that the transmission request command has been received.
Upon receiving the transmission request command, the terminal control unit (707) notifies the main control unit (704) that the transmission request command has been received.

When the main control unit (704) recognizes the transmission request command, the radio wave environment is measured via the wireless control unit (708). This radio environment measurement method is based on the wireless controller (7
08) tunes the frequency channels of the radio unit (703) from the lower frequency band and receives the radio wave of the frequency channel. The wireless control unit (708) notifies the main reception unit (704) of the highest reception level of the received radio wave, and the main control unit (704) stores the notification result in the memory (705) in order. This is divided into available frequency channels,
Repeat.

When the measurement of the radio wave environment is completed, the main control unit (704) examines the reception levels stored in the memory (705), assigns the frequency channels in ascending order of reception level, and at the time of data transmission, sets the frequency. The order in which the channels are used is also stored in the memory (705) (step S403).

The main controller (704) has a memory (7
05) in the order of the address and frequency channel stored in
Since it is recognized that the contents of the radio wave environment are stored, the radio wave environment of each frequency channel can be recognized by reading the contents of this memory. Then, by using the frequency channels in this order, the use of the frequency channels having a bad radio environment is avoided as much as possible.

Thereafter, using the hopping pattern frame (HPF) shown in FIG. 4, in order of good radio environment,
Numbers of frequency channels are assigned to HPs 1, 2, 3, ..., 25, 26 (for example, the frequency channel number is a binary number, '000011' if the channel is F3, '11010' if F26, etc.). Store. Further, the address of the data terminal of the transmission destination is stored in the UW of FSYN, and the transmission data terminal sets its HPF to the frequency channel F.
1 is transmitted (step S404).

The data terminal on the receiving side receives the above HPF through the frequency channel F1 and checks the contents of the UW (step S502). When the terminal recognizes that the data is addressed to its own terminal (YES in step S503), the terminal checks the contents of the data stored in HP1 to HP20 of the HPF, and determines the frequency channels of HP1 to HP20. Recognize (step S504). This allows the receiving-side data terminal to recognize the frequency channel for which frequency hopping is performed.

Next, the data terminal on the transmitting side is
5 depending on the frequency channels stored in P1, HP2, ...
Switching the frequency channel every ms, using the data frame shown in FIG. 5, until the actual data is transmitted,
The frequency channel is switched and data is transmitted (step S405). When transmitting the last data (YES in step S406), the data terminal on the transmitting side sends DT
The data transmission end bit is set in the LCCH of F and the data is transmitted (step S407). Then, when the transmission is completed, it waits again on the frequency channel F1 (step S401).

Further, the data terminal on the receiving side performs step S
5 by the frequency hopping pattern recognized in 504.
The frequency channel is switched every ms, and the data transmitted from the transmitting data terminal to the own data terminal is received (step S505). Then, when the end of the transmission data stored in the LCCH of the DTF is recognized (YES in step S506), the transmission side recognizes that the data transmission has ended, and stops the frequency hopping. After that, the frequency channel is switched to the frequency channel F1 that was initially in standby, and the reception is completed (step S501).

As described above, according to the present embodiment, when communication is started, the radio wave environment of the frequency channels in the usable frequency band is measured, and the radio waves of the frequency channels are ordered in descending order. By performing communication in the frequency hopping pattern according to the order, it becomes possible to avoid receiving erroneous data due to noise or the like.

By performing communication using the spread spectrum method, it is possible to solve the problems of communication confidentiality and noise generation.

The present invention may be applied to a system composed of a plurality of devices or an apparatus composed of a single device. Further, it goes without saying that the present invention can be applied to the case of being implemented by supplying a program to a system or an apparatus. In this case, the storage medium storing the program according to the present invention constitutes the present invention. Then, by reading the program from the storage medium into the system or device, the system or device operates in a predetermined manner.

[0047]

As described above, according to the present invention,
It is possible to avoid receiving erroneous data due to noise, etc. by assigning the order to the channels based on the measurement result of the radio environment of each frequency channel and performing communication with the frequency hopping pattern according to the order. ..

[0048]

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a wireless communication system according to an embodiment of the present invention.

FIG. 2 is a block diagram showing an internal configuration of a wireless adapter for connecting a data communication terminal.

FIG. 3 is a block diagram showing a configuration of a wireless unit according to the present system.

FIG. 4 is a diagram showing an overall configuration of an HPF.

FIG. 5 is a diagram showing an overall configuration of a DTF.

FIG. 6 is a diagram showing a structure of an FSYN frame.

FIG. 7 is a block diagram showing an internal configuration of a channel codec.

FIG. 8 is a diagram showing the concept of frequency hopping used in this system.

FIG. 9 is a flowchart showing the operation of the transmitting-side data terminal according to the present embodiment.

FIG. 10 is a flowchart showing the operation of the receiving side data terminal in the present embodiment.

[Explanation of symbols]

 101-A computer 101-B printer 101-C copier 101-D video conference terminal 101-E facsimile 101-F LAN bridge 701 data terminal 702 wireless adapter 703 wireless unit 704 main control unit 705 memory 706 communication i / f unit 707 Terminal control unit 708 Channel codec 709 Error correction processing unit 710 Timer

Claims (3)

[Claims] 1. A wireless communication system configured by a plurality of wireless communication devices that perform spread spectrum by frequency hopping according to a predetermined hopping pattern to transmit and receive on a plurality of frequency channels. Of these, means for measuring the radio wave environment of the usable channel, means for giving a predetermined order based on the measured radio wave environment to the usable frequency channel, and notifying the receiving side of the order. A wireless communication system comprising: a unit, a unit that performs transmission by frequency hopping according to the notified order, and a unit that performs frequency hopping and receives according to the notified order. 2. The wireless communication system according to claim 1, wherein the measurement is performed at the start of wireless communication by the wireless communication device on the transmitting side. 3. The radio according to claim 1, wherein the radio wave environment is a reception level of data, and the order is a number assigned to the frequency channels in order of increasing reception level. Communications system.