JPH08307367A - Interference avoidance method for wireless communication system - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a method for avoiding interference in a wireless communication system that can restart wireless communication immediately in a good state without disconnecting the communication link even when a strong interference wave is received during wireless communication. To provide. When a wireless signal having a data format for a normal mode to be received on channel 1 is interfered by another wireless signal, a wireless signal having a data format for an interference mode in which communication data is removed is generated. The communication partner station that has transmitted the wireless signal from which the communication data has been removed by transmitting on the channel 1 transmits the wireless signal having the data format for the interference mode on the channel 1 and both stations can transmit the control data in the wireless signal. After sharing information about other channels than channel 1 to
The wireless communication is restarted by moving to another channel and using a wireless signal having a data format for the normal mode.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an interference avoiding method for avoiding an interference wave in a wireless communication system to perform wireless communication.

[0002]

2. Description of the Related Art As a wireless communication system, for example, TDM
In a wireless communication system of A (Time Division Multiple Access) system, in order to communicate with a specific partner station, first, a plurality of communication is performed with a base station or a partner station on a control channel. One of the channels
After setting the communication channel of No. 1, the communication with the other station is actually started after moving to the one communication channel.

[0003]

When a strong interference wave is started from another station other than the communication partner station with the own station during communication on the communication channel, it is included in each time slot in order to avoid this interference. Although data such as communication channel switching will be exchanged using control data, the control data itself will play a sufficient role because a frame error will be detected by error detection and that information will be discarded. Cannot be performed, and as a result, the communication link between the two stations is disconnected, so that information transmission such as a call becomes impossible.

In order to restart wireless communication, it is necessary to establish a communication link on the control channel again and then move to the communication channel set there, so that it takes a long time to restart wireless communication. , Causing inconvenience to the user. Therefore, an object of the present invention is to provide an interference avoidance method for a wireless communication system capable of restarting wireless communication in a good state immediately without disconnecting the communication link even when a strong interference wave is received during wireless communication. That is.

[0005]

According to a method of avoiding interference in a wireless communication system of the present invention, a wireless signal having a data format for normal mode including communication data and control data is transmitted in a predetermined time slot to perform wireless communication. A method of avoiding interference when a radio signal being received is interfered by a radio signal from a station other than both stations that are in radio communication in a radio communication system that performs When one station determines that the radio signal to be received on the channel 1 is interfered by the other radio signal, the radio signal having the data format for the interference mode in which the communication data is removed is transmitted and the interference is generated. The other station of the two stations that has received the radio signal having the data format for the mode interferes with the one channel. After transmitting a radio signal having a data format for a channel, both stations share information about another channel other than channel 1 from control data in the radio signal having a data format for an interference mode, and then another channel. The wireless communication is resumed by a wireless signal having a data format for normal mode.

[0006]

Embodiments of the present invention will now be described in detail with reference to the drawings. In the wireless device to which the interference avoiding method of the wireless communication system of the present invention shown in FIG. 1 is applied, the antenna 1 is a transmitting / receiving antenna and a TDD (Time Divis).
ion Duplex) method is adopted. The receiving unit 3 and the transmitting unit 4 are connected to the terminals of the antenna 1 via the antenna switch 2.
Connected to either one of. The selection of the antenna switch 2 on the receiving unit 3 side is in a steady state. In the receiving unit 3, the high frequency signal which is the received signal from the antenna switch 2 is band-limited by the band limiting filter (BPF) 5 and then supplied to the high frequency amplifier 6. High frequency amplifier 6
The signal amplified by is supplied to the down converter 8 via the band limiting filter 7. Down converter 8
Generates an intermediate frequency signal by mixing the supplied high frequency signal with a local oscillation signal from the VCO 9. The level of the intermediate frequency signal is detected by the level detector 27 and supplied to the CPU (central processing unit) 19 as received electric field strength data. After the intermediate frequency signal output from the down converter 8 is digitized by the A / D converter 10,
It is supplied to a DSP (digital signal processor) 11. The DSP 11 detects the supplied digitized intermediate frequency signal, demodulates information signals such as a voice signal and a control signal included in the received signal, and the channel coder / decoder 12
Supply to. The DSP 11 also performs a modulation operation according to a data signal, which is a digital information signal to be transmitted, supplied from the channel coder / decoder 12, and supplies the modulation result to the transmission unit 4.

In the transmitter 4, the digital signal output from the DSP 11 is supplied to the up converter 14 via the D / A converter 13. Upconverter 14
Mixes the modulated signal with the oscillation signal from the VCO 15 and frequency-converts it to a frequency to be transmitted. The oscillation signal is amplified by the pre-stage amplifier 16 and further amplified by the power amplifier 17 to become a transmission radio signal. This transmission radio signal is supplied to the antenna 1 via the antenna switch 2.

The modulation and demodulation operations of the DSP 11 are performed by the CPU 1
Controlled by 9. The switching operation of the antenna switch 2, the oscillation frequencies of the VCOs 9 and 15 and the amplification operation of the power amplifier 17 are controlled by the operating state of the DSP 11.
The CPU 19 is a DSP in response to an operation from the keyboard 20.
11 and controls a channel coder / decoder 1
2 and the operation modes of the voice CODEC (codec) 21 are controlled. The channel coder / decoder 12 operates as a coder that performs a predetermined code conversion on the digital audio signal supplied from the voice CODEC 21 or the digital data signal supplied from the data input / output interface 22, and the signal after the code conversion is performed. To D
Supply to SP11. Further, it operates as a decoder for decoding the demodulated digital signal supplied from the DSP 11 and supplies the decoded digital signal to the voice CODEC 21 or the data input / output interface 22. The voice CODEC 21 converts the analog audio signal from the microphone amplifier 23 into a digital audio signal of a predetermined format, converts the decoded digital audio signal from the channel coder / decoder 12 into an analog signal, and supplies it to the speaker amplifier 24. To do. A microphone 25 is connected to the microphone amplifier 23, and a speaker 26 is connected to the speaker amplifier 24.

The data to be transmitted is first supplied from the CPU 19 to the channel coder / decoder 12, and the voice CO
It is supplied to the DSP 11 after being converted together with the communication data from the DEC 21 or the data input / output interface 22 into a data format according to the operation mode. Communication data is not included until the link is established. As the operation mode, there are a normal mode and an interference mode as will be described later, but it is usually set to operate in the normal mode. The DSP 11 performs data conversion on the supplied data signal by a modulation operation and supplies the data signal to the D / A converter 13. The data signal analogized by the D / A converter 13 is superimposed on the oscillation signal from the VCO 15 by the up converter 14. The oscillation signal including the data signal is amplified by the pre-stage amplifier 16 and further amplified by the power amplifier 17 to be a transmission signal, which is supplied to the antenna 1 via the antenna switch 2. On the other hand, the signal received by the antenna 1 is the antenna switch 2, the band limiting filter 5,
It is supplied to the down converter 8 via the high frequency amplifier 6 and the band limiting filter 7. The down converter 8 mixes the supplied signal with the local oscillation signal from the VCO 9 to form an intermediate frequency signal, which is digitized by the A / D converter 10 and then supplied to the DSP 11. DS
The signal demodulated in P11 is supplied to the channel coder / decoder 12. The channel coder / decoder 12 supplies control data to the CPU 19 and communication data to the voice CODEC 21 or the data input / output interface 22. That is, if the communication data is voice data, it is supplied to the voice CODEC 21, and if it is not voice data, it is supplied to the data input / output interface 22.

In the radio apparatus having such a configuration, for example, the output of the power amplifier 17 of the transmitting unit 4 can be increased at a predetermined timing and decreased after a predetermined time in a pre-allocated time slot as shown in FIG. Done. FIG. 3 shows a quadruple TDMA method in a synchronous wireless communication system, and wireless communication between a base station and the same mobile station at positions with the same slot number (slot number 1 in FIG. 3). Will be done.
The up period is a communication period from the mobile station to the base station, and the down period is a communication period from the base station to the mobile station. For example, data of 264 bits is transmitted in one time slot. In the data format for the normal mode of each slot, as shown in FIG. 4, a ramp at the start of transmission, a unique word serving as a sync signal, control data, communication data, and a CRC for error detection are usually used.
(Cyclic redundancy check), and then the ramp of the transmission fall. For example, a guard time for 8 bits is placed between slots. The numbers in parentheses in FIG. 3 are the number of bits. The CRC is a code that enables error detection for data in the range from the unique word in one slot to the communication data, and if a data error is detected based on this CRC, the data in this slot is ignored. It will be. This error detection is performed by the DSP 11 according to a predetermined error detection calculation formula, and when a slot having an error in data is detected, an error detection signal is supplied to the CPU 19.

The CPU 19 executes an interference avoidance routine each time an error detection signal is supplied from the DSP 11. In the interference avoidance routine, as shown in FIG.
First, 9 determines whether or not the error detection signal is continuously generated a predetermined number of times N (N ≧ 2) or more (step S1). For example, the number of occurrences of the error detection signal is counted by using a counter, and if the error detection signal does not occur within a predetermined period, the count value is reset to an initial value 0 so that the error detection signal is The count value of the counter does not reach the predetermined number N unless it occurs consecutively more than the predetermined number N.
A predetermined number of times N without resetting the count value of the counter
If it is equal to, it can be determined that the error detection signal has been generated consecutively N times or more.

When the error detection signal is generated a predetermined number of times N or more in succession, it is determined whether or not the received electric field strength obtained from the level detector 27 is larger than a specified value (step S2). If the received electric field strength is equal to or less than the specified value, it is determined that the interference has not occurred and the communication area is out of the communication area. Therefore, this routine ends. On the other hand, if the received electric field strength is higher than the specified value, it can be considered that interference has occurred.
The DSP 11 and the channel coder / decoder 12 are instructed to change the slot data format to the interference mode (step S3). In the data format for the interference mode, as shown in FIG. 6, the ramp at the rising edge of the transmission, the unique word serving as the synchronization signal, the control data, the CRC for error detection, and the ramp at the falling edge of the transmission are in this order. That is, the data format for the interference mode is the one in which the communication data area in the data format for the normal mode shown in FIG. 4 is deleted, and the content can be a short transmission time. The control data consists of 8 bits of bits 0 to 7, and bit 7 is 0 in the normal mode and 1 in the interference mode. Further, in the interference mode, the channel number of the transfer destination is indicated to the partner station by bits 3 to 0. Therefore, when the radio signal having the data format for the interference mode is transmitted to the partner station in the pre-assigned time slot and the control data in the signal received by the partner station is confirmed, bit 7 from the partner station is then detected. It becomes 1 indicating the interference mode, and bits 3 to 0 indicate the channel number of the transfer destination.

After executing step S3, the CPU 19 determines whether or not the partner station has confirmed the communication channel shift (step S4). This is discriminated from the contents of the received control data supplied from the channel coder / decoder 12 to the CPU 19. If the content of the received control data indicates the interference mode and does not indicate the channel number of the transition destination, the process returns to step S3 and the above step S3.
And the operations of S4 are repeated. If it is determined from the content of the received control data that the partner station has confirmed the communication channel transfer, the transfer to a new communication channel is instructed (step S5). As a result, the oscillation frequencies of the VCOs 9 and 15 correspond to the new communication channel,
The wireless communication is restarted in the data format for the normal mode (step S6).

When the partner station confirms the communication channel number to be transferred, it immediately transfers to a new communication channel after transmitting a radio signal having a data format for interference mode. FIG. 7 shows time slots of stations A and B when station A is interfered by a radio signal from station B other than the communicating station in the asynchronous radio communication system. Station A has reached time slots in the order of (a)->(b)->(c)-> (d), and station B is generating radio signals from the time slot of (b). (A) shows the case where only the A station transmits on the communication channel CH1, and (b) shows the case where the A station is interfered by the radio signal from the B station when transmitting on the communication channel CH1. The hatched parts interfere with each other and the call is disabled. (C) shows the time of transmission in the interference mode of each of A station and B station. In these (a) to (c), the communication channel CH1 is used. In (d), station A has a call channel CH2.
And the call is restarted, and station B receives call channel CH3.
The call has been resumed by moving to.

FIG. 8 shows time slots of stations A and B when station A is interfered by a radio signal from station B other than the communicating station in the synchronous radio communication system. Station A has reached time slots in the order of (a)->(b)->(c)-> (d), and station B is generating radio signals from the time slot of (b). (A) shows the case where only the A station transmits on the communication channel CH1, and (b) shows the case where the A station is interfered by the radio signal from the B station when transmitting on the communication channel CH1. Since it is a synchronous system, for example, the A and B stations in the same area are controlled by the base station so as to have the same transmission timing, so that they interfere with each other over the entire period as indicated by hatching. Therefore, the call is disabled. (C)
Indicates the time of transmission in the interference mode of each of station A and station B. Stations A and B need to be arranged so that their transmission timings do not coincide with each other in the interference mode. For example, if the least significant digit of the ID number of each station is odd, it may be transmitted at the beginning of the time slot, and if it is even, it may be transmitted at the end. Alternatively, each station may start transmission at random timing within a time slot. In these (a) to (c), the communication channel CH1 is used. In (d), A
The station shifts to the call channel CH2 and restarts the call, and B
The station shifts to the call channel CH3 and restarts the call.

The destination communication channel may be set in advance, or an unused unused communication channel may be actually received and detected. INDUSTRIAL APPLICABILITY The present invention can be applied to a wireless cordless telephone system such as a PHS (personal handy system) as well as an MCA (multi-channel access) system, a personal radio system or a mobile telephone system as a wireless communication system.

[0017]

As described above, in the interference avoidance method of the wireless communication system according to the present invention, the wireless signal having the data format for the normal mode to be received on one channel is interfered by the other wireless signals. In this case, a radio signal having a data format for interference mode with communication data removed is transmitted on one channel, and a communication partner station that has received the radio signal with communication data removed has a data format for interference mode. The signal is transmitted on one channel, and both stations share information about other channels other than the one channel from the control data in the wireless signal, and then move to the other channel to have a wireless mode having a data format for normal mode. Since the wireless communication is restarted using the signal, even if a strong interference wave is received during the wireless communication, the communication link You can restart the radio communication immediately good state without cutting.

[Brief description of drawings]

FIG. 1 is a block diagram showing a wireless device to which an interference avoidance method of the present invention is applied.

FIG. 2 is a diagram showing a change in transmission power in a time slot.

FIG. 3 is a diagram showing allocation of time slots in the case of a quadruple TDMA method.

FIG. 4 is a time slot data format in a normal mode.

FIG. 5 is a flowchart showing the operation of the CPU.

FIG. 6 is a data format of a time slot in the interference mode.

FIG. 7: A station is B in an asynchronous wireless communication system
It is a figure which shows the time slot of A station and B station when it receives interference by the radio signal from a station.

FIG. 8 is a diagram showing time slots of stations A and B when station A is interfered by a radio signal from station B in the synchronous wireless communication system.

[Explanation of symbols for main parts]

 1 Antenna 3 Receiver 4 Transmitter 11 DSP 12 Channel Coder / Decoder 19 CPU 21 Voice CODEC 22 Data Input / Output Interface

Claims (8)

[Claims] 1. A station other than both stations in wireless communication in a wireless communication system for performing wireless communication by transmitting a wireless signal having a data format for normal mode including communication data and control data in a predetermined time slot. An interference avoidance method for avoiding interference of a radio signal being received by a radio signal from the device, wherein the radio signal to be received in one channel by one of the two stations is When it is determined that interference has been caused by a radio signal other than the above, a radio signal having a data format for the interference mode in which communication data is removed is transmitted, and a radio signal having the data format for the interference mode is received. The other of the stations is a radio signal having a data format for the interference mode on the one channel. The two stations share the information about the other channel other than the one channel from the control data in the radio signal having the data format for the interference mode, and then move to the other channel for the normal mode. Interference avoidance method, characterized in that wireless communication is restarted by a wireless signal having the above data format. 2. An error detection code is inserted in the wireless signal, and an error of data included in a wireless signal received using the error detection code is continuously detected a predetermined number of times or more and the received wireless signal is received. The interference avoiding method according to claim 1, wherein when it is detected that the electric field strength of the signal is higher than a specified value, it is determined that the wireless signal to be received is interfered with by another wireless signal. 3. The control data in the radio signal having the data format for the interference mode, which is transmitted when it is determined that the one station receives interference, indicates the number of the other channel. The interference avoidance method according to claim 1. 4. When the other station receives a radio signal having a data format for the interference mode, the other station detects the number of the other channel indicated in the control data in the radio signal and detects the other channel. A radio signal having a data format for the interference mode including control data indicating the number of 1 is transmitted on the one channel, and the one station transmits a radio signal having the data format for the interference mode from the other station. When it is received, it is confirmed that the number of the other channel indicated in the control data in the radio signal matches the number of the other channel of the transmitted control data, and then the channel is moved to the other channel. The interference avoidance method according to claim 3. 5. The interference avoidance method according to claim 1, wherein the control data includes a bit indicating the presence or absence of interference. 6. The interference according to claim 1, wherein when the wireless communication system is asynchronous, a wireless signal having a data format for the interference mode is transmitted at the start of the predetermined time slot. Workaround. 7. A wireless signal having a data format for the interference mode is transmitted at a time point determined for each station in the predetermined time slot when the wireless communication system is a synchronous type. The interference avoidance method according to claim 1. 8. The wireless signal having the data format for the normal mode has a transmission rising ramp, a unique word, control data, communication data, an error detection code, and a transmission falling ramp, in that order. 2. The interference avoiding method according to claim 1, wherein the wireless signal having the data format for the mode is in the order of a ramp at the rising edge of the transmission, a unique word, control data, an error detection code, and a ramp at the falling edge of the transmission.