JP2001237853A - Radio communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily control a transmission range by avoiding mutual interference of a transmission radio wave so as to ensure the transmission even when a plurality of transmitters is in existence around a transmitter in order to adopt a broadcast system for packet communication and allow each radio communication terminal to stop returning depending on remaining number of hopping. SOLUTION: The radio communication system is a system that transmits a packet signal according to the broadcast system and each transmitted packet signal is set with a remaining hop number denoting number of radio communication terminals desired to be returned. When the remaining hop number included in the received packet signal indicates a numeral of '1' or over, each radio communication terminal sets again a numeral subtracting '1' from this figure to the packet signal as a remaining hop number and returns the packet signal. On the other hand, when the remaining hop number of the received packet signal is '0', the returning is stopped.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radio communication system, and more particularly to a radio communication system for transmitting a packet signal to a plurality of radio communication terminals in a broadcast system.

[0002]

2. Description of the Related Art When transmitting a common information signal such as an advertisement to a plurality of receivers by radio, in the prior art, the transmission range is controlled by adjusting the power on the transmitter side. In other words, when you want to send a signal far away, increase the power,
When we wanted to keep transmissions in a narrow range, we reduced the power.

[0003]

However, when there is another transmitter around, it is impossible to control the transmission range by power as in the prior art. That is, when there are a plurality of transmitters in the vicinity and each transmitter emits a radio wave, the radio waves interfere with each other and the signal level is reduced. As a result, the range that can be actually transmitted becomes narrower than the initially expected range. Conversely, if each transmitter weakens the power to eliminate interference, the transmission range is inherently narrow. Therefore, in a situation where a plurality of transmitters exist in the vicinity, transmission itself may sometimes be difficult due to mutual interference of transmission radio waves, and control of the transmission range is also difficult.

[0004] Therefore, a main object of the present invention is to ensure the transmission by avoiding mutual interference of transmission radio waves and to easily control the transmission range even in a situation where a plurality of transmitters are present in the surrounding area. It is to provide a wireless communication system.

[0005]

SUMMARY OF THE INVENTION The present invention relates to a radio communication system for transmitting a packet signal to a plurality of radio communication terminals in a broadcast system, wherein the packet signal includes a numerical value indicating the number of times of transmission of the packet signal. The communication terminal receives the packet signal from another wireless communication terminal, receives the packet signal from another wireless communication terminal, compares the numerical value included in the packet signal received by the receiving unit with a predetermined value, and the comparison result of the numerical comparison unit indicates a mismatch. Updating means for updating the numerical value, forwarding means for forwarding a packet signal containing the numeric value updated by the updating means to another wireless communication terminal, and disabling the forwarding means when the comparison result of the numerical comparing means indicates a match. (1) comprising disabling means;
It is a wireless communication system.

[0006]

In this wireless communication system, the packet signal is
The broadcast is transmitted to a plurality of wireless communication terminals. The transmitted packet signal includes a numerical value indicating the number of times of transmission of the packet signal. Therefore, the following processing is performed in each wireless communication terminal. First, a packet signal is received from another wireless communication terminal by the receiving means, and the received packet signal is subjected to decoding processing. The numerical value comparing means compares a numerical value included in the received packet signal with a predetermined value. Here, if the comparison result of the numerical value comparing means indicates a mismatch, the updating means updates the numerical value,
The forwarding means forwards the packet signal including the updated numerical value to another wireless communication terminal. On the other hand, if the comparison result of the numerical value comparison means indicates a match, the first disabling means disables the forwarding means.

As described above, since the broadcast system is employed for packet communication, packet signals can be transmitted over a wide range without increasing transmission power as in the prior art. In addition, since each wireless communication terminal stops forwarding according to the value indicating the number of times of transmission, mutual interference of transmitted radio waves is avoided, transmission is reliably performed, and the transmission range is easily controlled by the value indicating the number of times of transmission. Is done.

In one embodiment of the present invention, the reception state or the reception power of the packet signal received by the receiving means is detected by the first detecting means. The determining means determines a packet signal forwarding standby time based on the detected reception state or received power, and the forwarding means performs forwarding when the forwarding standby time has elapsed. This avoids a situation in which traffic is congested all at once. The forwarding standby time is preferably longer as the reception state is better or the reception power is larger.

In one aspect of the present invention, the traffic congestion state is determined by the traffic determination means.
The extension means extends the forwarding standby time according to the result of the determination. For this reason, the packet signal is transmitted when there is a margin in the traffic.

[0010] In another aspect of the present invention, each packet signal includes a different identifier for each packet, and the identifier is detected by the second detector. The detected identifier is compared with the identifier included in the packet signal waiting for forwarding by the first identifier comparing means. On the other hand, the reception state or the reception power when the packet signal waiting for forwarding is received is determined by the determination unit. The second disabling means disables the forwarding means in accordance with the comparison result of the first identifier comparing means and the determination result of the reception state determining means. By stopping forwarding when a packet signal having the same identifier is being forwarded through another wireless communication terminal, traffic congestion is prevented.

In another embodiment of the present invention, each packet signal contains content information and an identifier which differ from packet to packet. In each wireless communication terminal, the decoding means decodes the content information, and the third detection means detects the identifier.
The second identifier comparing means compares the currently detected identifier with an identifier detected in the past, and if the comparison result indicates a match,
Third disabling means disables the decoding means. If the same packet signal has been received in the past, it is not necessary to disable the same content information, so the decoding means is disabled.

In another embodiment of the present invention, the packet signal is a first packet signal transmitted through any one of a plurality of channels, and has the channel information of the first packet signal and precedes the first packet signal. And a second packet signal transmitted through a specific channel. When the second packet signal is received through a specific channel,
Channel information included in the second packet signal is detected by the channel information detecting means. The channel switching means switches the receiving channel based on the detected channel information. For this reason, the first packet signal following the second packet signal is reliably received.

[0013] Preferably, the channel information detected by the channel information detecting means is stored in a memory. Further, the forwarding channel determining means determines a channel having low correlation with the channel indicated by the channel information stored in the memory as the first channel.
It is determined as a packet signal forwarding channel. For this reason, it is possible to prevent the traffic of the container channel from being congested.

[0014]

According to the present invention, each radio communication terminal
When a numerical value included in the received packet signal is larger than a predetermined value, the numerical value is updated, and a packet signal including the updated numerical value is transmitted to another wireless communication terminal. On the other hand, if the numerical value included in the received packet signal is equal to the predetermined value, the forwarding is stopped. As described above, since the broadcast method is used for transmitting the packet signal, and each wireless communication terminal stops forwarding in accordance with the numerical value included in the packet signal, even if there are a plurality of transmitters in the vicinity, mutual transmission of transmission radio waves is not possible. The transmission can be ensured by avoiding interference, and the transmission range can be controlled only by adjusting the numerical value included in the packet signal.

The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description of embodiments with reference to the accompanying drawings.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The wireless communication system of this embodiment is formed by a plurality of wireless communication terminals, and each wireless communication terminal transmits a packet signal to another wireless communication terminal in a broadcast system.

There are two types of packet signals to be transmitted. One is a broadcast packet having a structure as shown in FIG. 2A, and the other is a container packet having a structure as shown in FIG. 2B. The broadcast packet is transmitted through a specific channel called a broadcast channel, and the container packet is transmitted through any one of a plurality of channels called a container channel.

Referring to FIG. 2A, the broadcast packet includes a header portion and a data portion. The header portion includes the remaining hop number and sequence number, and the data portion includes container channel information. The number of remaining hops is
It has a numerical value related to the number of wireless communication terminals to which packets are forwarded (the number of times of forwarding). This value is decremented every time a packet is forwarded, and when the value becomes "0", forwarding is stopped. The sequence number is a unique identifier assigned to each broadcast packet, and is used to prevent duplicate forwarding processing when the same broadcast packet is received a plurality of times. The container channel information is information indicating a communication channel of a container packet transmitted subsequent to the broadcast packet.
By switching the receiving channel according to the container channel information, the subsequent container packet can be properly received.

As can be seen from FIG. 2B, the container channel also includes a header section and a data section. However, only the sequence number is included in the header part, and the content information is included in the data part. The sequence number is
It has the same number as the preceding broadcast packet. Each wireless communication terminal specifies a container packet related to the preceding broadcast packet by this sequence number. The content information is subjected to predetermined output processing in each wireless communication terminal, and is output from a display or a speaker.

Each wireless communication terminal is specifically configured as shown in FIG. The radio wave reception circuit 10 receives radio waves of the channel set by the reception channel control circuit 20 and inputs a received radio wave signal to the reception power measurement circuit 22 and the packet reception circuit 12. Received power measurement circuit 22
Measures the power of the input received radio wave signal, that is, the signal level, and gives the measurement result to the CPU 30. The packet receiving circuit 12 determines whether the received radio wave signal output from the radio wave receiving circuit 10 includes a packet signal. When the packet signal is detected, the packet receiving circuit 12 converts the packet signal into a packet analysis circuit 14 and an error rate analysis circuit. 24. When a packet signal is detected in the broadcast channel, the packet receiving circuit 12 outputs a packet detection signal to the CPU 30, the packet transmission circuit 34, and the transmission channel control circuit 16.

The error rate analysis circuit 24 analyzes the error rate of the given packet signal and outputs the analyzed error rate to the packet transmission circuit 34. On the other hand, the packet analysis circuit 14
Analyzes the packet signal given from the packet receiving circuit 12, and gives the analysis result to the receiving channel control circuit 20, the sequence number memory 26, the remaining hop number memory 28 or the content information memory 29. That is, if the packet signal detected by the packet receiving circuit 12 is a broadcast packet, the remaining hop number included in the header portion is written in the remaining hop number memory 28, and the sequence number included in the header portion is stored in the sequence number memory 26. To the receiving channel control circuit 20.
On the other hand, if the detected packet signal is a container packet, the sequence number contained in the header part of this packet is written into the sequence number memory 26 shown in FIG. Write to the information memory 29. The sequence number memory 26 also stores attribute information such as a reception time and an error rate evaluation value described later.

The reception channel control circuit 20 sets a broadcast channel to the radio wave reception circuit 10 in a steady state. When container channel information is given from the packet analysis circuit 14, the channel number indicated by the container channel information is displayed. The data is written into the used channel history memory 18 in the manner shown in FIG. 3 and the channel number is set in the radio wave receiving circuit 10 for a predetermined time. As a result,
The container packet transmitted through the container channel following the broadcast packet is transmitted to the radio wave receiving circuit 1.
0 is properly received. The used channel history memory 18 also stores attribute information such as a set time.

The packet transmitting circuit 34 receives the packet detection signal from the packet receiving circuit 12, and the number of remaining hops (stored in the remaining hop number memory 28) included in the received broadcast packet is larger than "0". At this time, the error rate output from the error rate analysis circuit 24 is taken in, and the forwarding standby time is calculated based on the error rate. The calculated forwarding standby time is set in a counter 34a built in the packet assembling circuit 34, and the counter 34a
Is decremented in response to a predetermined timing signal. When the value of the counter 34a becomes "0", the packet transmission circuit 34 instructs the transmission channel control circuit 16 to output the container channel information and gives a packet assembling instruction to the packet assembling circuit 36.

When the broadcast packet and the container packet are assembled by the packet assembling circuit 36, the packet transmitting circuit 34 performs a forwarding process for each of the assembled packets. First, the start of forwarding is notified to the transmission channel control circuit 16, and subsequently, a broadcast packet and a container packet are output to the radio wave transmission circuit 32 in this order. In the radio wave transmission circuit 32,
The transmission channel control circuit 16 first sets a broadcast channel, and then sets a container channel. Therefore, each of the broadcast packet and the container packet is forwarded to surrounding wireless communication terminals through the broadcast channel and the container channel.

If the forwarding stop command is given from the CPU 30 before the value of the counter 34a becomes "0", the packet transmitting circuit 34 stops outputting (forwarding) the packet signal. In addition to such a forwarding stop command, the CPU 30 also issues a forwarding standby time extension command or a shortening command to the packet transmission circuit 34. At this time, the packet transmission circuit 3
No. 4 changes the value of the counter 34a according to the content of the instruction.

The packet assembling circuit 36, when given an assembling command from the packet transmitting circuit 34, assembles each packet as follows. When assembling a broadcast packet, first, the remaining hop number and sequence number that are analyzed by the packet analysis circuit 14 and stored in the sequence number memory 26 and the remaining hop number memory 28 are read. Then, the sequence number is set as it is in the header part of the broadcast packet, and the remaining hop number is set in the header part by subtracting “1” from the read numerical value. Subsequently, the container channel information output from the transmission channel control circuit 34 is fetched, and the fetched container channel information is set in the data portion of the broadcast packet.

When assembling the container channel, the same sequence number as described above is stored in the sequence number memory 26.
And the content information is read from the content information memory 29. Then, the sequence number is set in the header part of the container packet, and the content information is set in the data part of the same container packet.

Since the packet assembling by the packet assembling circuit 36 is performed for the purpose of forwarding the received packet, the sequence number memory 26, the remaining hop number memory 28, and the content information memory 29 are used.
, A sequence number, a remaining hop number, and content information related to each other are read. The packet assembling circuit 36 assembles the broadcast packet and the container packet in the same manner as described above not only when transmitting the received packet signal but also when transmitting the packet signal spontaneously. in this case,
All of the content information, the remaining hop number, and the sequence number are provided from the CPU 30 to the packet assembling circuit 36.

When a container channel output command is given from the packet transmission circuit 34, the transmission channel control circuit 16 determines a channel to be used for transmission of the current container channel, and transmits container channel information indicating the determined channel to packet assembly information. Output to the circuit 36. Also, when the forwarding start notification is given from the packet transmission circuit 34, the broadcast channel is first set to the radio wave transmission circuit 32, and then the container channel determined in response to the container channel output command is transmitted to the radio wave transmission circuit 32. Set to. The transmission channel control circuit 16 further obtains a correlation between the determined container channel and the container channel information used for receiving the container packet when the packet detection signal is given from the packet reception circuit 12,
Reset the determined container channel when the correlation is high.

When a packet detection signal is output from the packet receiving circuit 12, the CPU 30 receives a plurality of sequences received in the past and stored in the sequence number memory 26, the same number as the sequence number included in the broadcast packet received this time. Search from numbers. If the same sequence number is not found, output processing of the content information included in the received container packet following the broadcast packet is performed. Specifically, the sequence number and the content information analyzed from the container packet are fetched from the packet analysis circuit 14, and when the fetched sequence number matches the sequence number of the preceding broadcast packet, decoding processing is performed on the fetched content information at the same time. Apply. on the other hand,
If the same number as the sequence number included in the broadcast packet received this time is found and a packet with the same sequence number is in the forwarding standby state, forwarding is stopped according to the error rate when receiving the waiting packet. An instruction or an instruction to shorten the forwarding standby time is given to the packet transmission circuit 34. The reason for giving such an instruction will be described later.

When the packet is in the forwarding waiting state, the CP
U30 compares the reception signal level (reception noise level) with a predetermined threshold value even when the packet detection signal is not output from the packet reception circuit 12. If the reception noise level exceeds a predetermined threshold, it considers that surrounding traffic is congested, and gives the packet transmission circuit 34 an extension of the forwarding standby time.

The packet transmission circuit 34 is described in detail in FIG.
It operates according to the flowchart shown in FIG. The packet transmission circuit 34 is actually configured by a logic circuit,
For convenience of explanation, such a flowchart is used.

In step S1, the packet receiving circuit 12
Judge whether a packet detection signal is output from
If it is ES, it is determined that the broadcast packet has been received, and the process proceeds to step S25. In this step, it is determined whether or not the remaining hop number written in the remaining hop number memory 28 is “0”. If the number of remaining hops is "0", it is determined that there is no need to perform the forwarding process, and the process returns to step S1 without performing the processes of steps S27 and S29. On the other hand, if the number of remaining hops is equal to or more than "1", the error rate of the broadcast packet received this time (output from the error rate analysis circuit 24) is evaluated in step S27.
The forwarding waiting time is obtained according to the following.

[0034]

Wt = Rnd (Tw) + Eg × Tw Wt: Forwarding standby time Tw: Reference value Rnd (Tw): Any numerical value equal to or less than Tw Eg: Error rate evaluation value Reference value Tw is, for example, “4”. Rnd (Tw) is, for example, “0”, “1”, “2”, “3” or “4”.
Take the value of The error rate evaluation value Eg takes a value of, for example, "0", "1", or "2" in order from a higher error rate. Therefore, if the error rate evaluation value Eg is “0”, the forwarding standby time Wt indicates any of “1” to “4”, and if the error rate evaluation result Eg is “1”, the forwarding standby time Wt
Indicates any one of "5" to "8", and if the error rate evaluation result Eg is "2", the forwarding standby time Wt is "9" to "1".
2 ". In other words, the forwarding standby time Wt is
The longer the error rate is, the longer the error rate is. When the forwarding waiting time Wt is calculated, the process returns to step S1. The calculated forwarding standby time Wt is set in the counter 34a and is decremented in response to a predetermined timing signal.

FIG. 9 shows each wireless communication terminal constituting the wireless communication system of this embodiment. When a packet is transmitted from the wireless communication terminal A and the transmitted packet is received by the wireless communication terminals B, C, and D, the error rate of the received packet increases as the distance increases (in the order of C → B → D). ) Increases, and the error rate evaluation value Eg decreases (in the order of C → B → D) as the distance increases. Wireless communication terminal C
If the error rate evaluation value Eg of the wireless communication terminal B is “2”, the error rate evaluation value Eg of the wireless communication terminal B is “1”, and the error rate evaluation value Eg of the wireless communication terminal D is “0”, the wireless communication terminal C Is the transfer waiting time Wt of any one of “9” to “12”, the forwarding waiting time Wt of the wireless communication terminal B is any of “5” to “8”, and the forwarding waiting time Wt of the wireless communication terminal D is "1" ~
It becomes one of "4". Thus, the forwarding standby time W
t decreases as the error rate evaluation value Eg decreases, that is, as the error rate of the received packet increases.

Returning to FIG. 5, if NO is determined in step S1, it is determined in step S3 whether the packet is in a forwarding standby state. If it is not in the forwarding standby state, the process directly returns to step S1, but if it is in the forwarding standby state, the process proceeds to step S5, and it is determined whether or not the forwarding standby time Wt, that is, the value Wt of the counter 34a has become "0". Here, if the value of the counter 34a is larger than "0", the presence or absence of a command from the CPU 30 is determined in each of steps S13, S17 and S21.

When a forwarding stop command is given from the CPU 30, YES is determined in the step S13, and the step S1 is determined.
In step 5, the forwarding of the packet is stopped. Specifically, the value of the counter 34a is reset, the number of remaining hops used for the current forwarding process is deleted from the remaining hop number memory 28, and the process returns to step S1. On the other hand, when the CPU 30 has issued the standby time extension command, the process proceeds to step S19 via steps S13 and S17, and the above-described reference value Tw is added to the current value Wt of the counter 34a. Then, the process returns to step S1. On the other hand, when the CPU 30 gives a command to reduce the standby time, steps S13 and S1 are executed.
After step 7 and step S21, the process proceeds to step S23, where the above-described reference value Tw is subtracted from the current value Wt of the counter 34a. Then, the process returns to step S1.

In step S5, the forwarding standby time Wt is "0".
If it is determined that, the transmission container channel output instruction is given to the transmission channel control circuit 16 in step S7, and the packet assembly instruction is given to the packet assembly circuit 36 in step S9. After that, the packet assembly circuit 36 waits for the completion of the broadcast packet and the container packet, and then performs forwarding processing of these packets in step S11. That is, first, the transmission channel control circuit 1
6 and a broadcast start notification is given to the radio wave transmitting circuit 32 at a predetermined timing. A broadcast channel and a container channel are set in the radio wave transmitting circuit 32 at a predetermined timing, and the broadcast packet and the container packet are transmitted (forwarded) through the respective channels.

The packet assembling circuit 36 is shown in FIG.
It operates according to the flowchart shown in FIG. Packet assembly circuit 3
6 is also actually constituted by a logic circuit, but will be described with reference to a flowchart for convenience of explanation.

First, in step S31, it is determined whether or not a packet assembling command is given from the packet transmitting circuit 34.
When the determination result of YES is obtained, the processing after step S33 is performed. In steps S33 and S35, the number of remaining hops and the sequence number are set in the header part of the broadcast packet. In the following step S37, the container channel information is set in the data part of the same broadcast packet. The remaining hop number and the sequence number are stored in the remaining hop number memory 28 and the sequence number memory 26, and are stored in steps S33 and S33.
At 35, the number of remaining hops and the sequence number are set. On the other hand, in step S37, the container channel information output from the transmission channel control circuit 16 is set.

In subsequent steps S39 and S41, a sequence number is set in the header portion of the container packet, and content information is set in the data portion of the same container packet. The sequence number is the same as the sequence number set in the above step S35,
It is read from the sequence number memory 26 and set. On the other hand, the content information is read from the content information memory 29 and set. When the related broadcast packet and container packet are assembled in this way, the process returns to step S31.

The transmission channel control circuit 16 operates according to the flowchart shown in FIG. This transmission channel control circuit 16 is also actually constituted by a logical value circuit, and the flowchart is used for convenience of explanation.

First, it is determined in step S5 whether a container channel output instruction has been given from the packet transmission circuit 34.
1 and the packet detection signal is
Is determined in step S61, and whether or not a forwarding start notification is provided from the packet transmission circuit 34 is determined in step S71.

If a container channel output command has been given, the flow advances to step S53 to determine whether a transmission container channel has been determined. If the transmission container channel has not been determined yet, the process proceeds to step S55.
A list of a plurality of container channels having low correlation with the container channels stored in the used channel history memory 18 shown in FIG. In step S57, a container channel to be actually used is determined from the plurality of container channels listed, and when the determination process is completed, the process proceeds to step S59. In step S59, the container channel information determined or determined in step S57 is output to the packet assembling circuit. And step S
Return to 51.

When a packet detection signal is given, it is determined in step S63 whether or not the transmission container channel has been determined.
Return to 1. On the other hand, if the transmission container channel has been determined, the process proceeds to step S65, and the correlation between the container channel information included in the broadcast packet received this time and the determined container channel is calculated. In step S67, it is determined whether or not the calculated correlation is higher than a predetermined threshold. If the correlation is low, the process returns to step S51. If the correlation is high, the transmission container channel is reset in step S69, and then step S51 is performed.
Return to As a result of the reset processing in step S69, the transmission container channel is in an undecided state.

If the forwarding start notice is given, YES is determined in the step S71, and the steps S73 and S75 are determined.
, The broadcast channel and the container channel are set in the radio wave transmission circuit 32. The setting timing of each channel coincides with the forwarding timing of the broadcast packet and the container packet, and step S7
The container channel set in 5 is a channel indicated by the container channel information output in step S59.

The CPU 30 specifically processes the flowchart shown in FIG. First, it is determined in step S81 whether a packet detection signal has been output from the packet receiving circuit 12. Here, if YES is determined, the process proceeds to step S83.
Then, the same sequence number as the sequence number included in the broadcast packet received this time is detected in the past and searched from the sequence numbers stored in the sequence number memory 26. In a succeeding step S85, it is determined whether or not the same sequence number is found. If NO, the process proceeds to step S87, where the content information of the container packet having the same sequence number as the broadcast packet is read from the content information memory 29 and output processing is performed. That is, a process for outputting a desired image and sound from a display and a speaker (both not shown) is performed. Upon completion of the process, the process returns to the step S81.

If the same number as the sequence number included in the broadcast packet received this time is found from the sequence number memory 26, it is determined in step S95 whether or not the packet is in the forwarding standby state. It returns to step S81 as it is. That is, the broadcast packet received this time is a broadcast packet received at least once in the past, and there is no need to perform the output processing of the content information again, and it is not necessary to perform the forwarding processing. Therefore, if NO is determined in the step S95, the process returns to the step S81 without performing any processing. Therefore, the currently received container packet is invalidated.

It is the radio communication terminal D shown in FIG. 9 that performs the process of returning from step S95 to step S81. As described above, the forwarding standby time W of the wireless communication terminal D
When t is the shortest and the same broadcast packet is received from the wireless communication terminal C, the forwarding process is completed. Therefore, when receiving the broadcast packet from the wireless communication terminal C, the wireless communication terminal D invalidates the subsequent container packet.

If it is determined in step S95 that there is a packet waiting to be forwarded, the flow advances to step S97 to determine whether the sequence number of the packet waiting and the sequence number included in the broadcast packet received this time match. to decide. If the sequence numbers do not match, there is no relationship between the packet received this time and the waiting packet, and the process directly returns to step S81 for the same reason as described above. On the other hand, if the respective sequence numbers match, it is determined whether or not the error rate evaluation value Eg at the time of receiving the waiting packet is “0” at step S9.
Judge at 9. Then, if the error rate evaluation value Eg is “0”, in step S 101, the command to stop forwarding the waiting packet is output to the packet transmitting circuit 34. On the other hand, if the error rate evaluation value Eg is “1” or “2”, a command to reduce the forwarding standby time is output to the packet transmitting circuit 34 in step S103. Upon completion of the process in the step S101 or S103, the process returns to the step S81.

The reason why YES is determined in the step S97 is that
This is the wireless communication terminal B shown in FIG. Between the wireless communication terminals B and D, the forwarding standby time of the wireless communication terminal D is shorter, and when the wireless communication terminal B is waiting for the forwarding of a packet, the wireless communication terminal D The same broadcast packet is sent. At this time, the wireless communication terminal B determines YES in step S97, and compares the signal level of the packet received from the wireless communication terminal A with a predetermined threshold in step S99. Then, step S101 or S103 is processed according to the comparison result. Error rate evaluation value Eg of the packet received from wireless communication terminal A
If “0”, a forwarding stop command is output in step S101, and the wireless communication terminal E receives the packet only from the wireless communication terminal D. On the other hand, if the error rate evaluation value Eg of the packet received from the wireless communication terminal A is “1” or “2”, the forwarding standby time Wt is determined by the processing in step S103.
Is shortened.

In the broadcast system, since the same packet is transmitted from a plurality of wireless communication terminals, there is no problem if any of the wireless communication terminals stops forwarding. Rather, stopping the forwarding prevents traffic congestion. it can. Furthermore, if the error rate evaluation value Eg is small, this packet has been transmitted from a wireless communication terminal that is relatively close, and there is little need to forward the packet. Therefore, when the error rate evaluation value Eg is small, the forwarding of the packet is stopped in step S101. Step S
The reason for performing the process 103 will be described later.

While no packet detection signal is output, NO is determined in the step S81, and the processes after the step S89 are executed. In the step S89, it is determined whether or not the packet is in a forwarding standby state. If “NO”, the process directly returns to step S81, but if “YES”, the process proceeds to step S91 to compare the current reception signal level, that is, the reception noise level, with a predetermined threshold. Here, if the reception noise level is higher than the predetermined threshold, it is considered that the surrounding traffic is congested, and if the reception noise level is equal to or lower than the predetermined threshold, it is considered that the surrounding traffic has room. Therefore, when it is determined that “reception noise level ≦ predetermined threshold”, the process directly returns to step S81, and when it is determined that “reception noise level> predetermined threshold”, an extension instruction of the forwarding standby time Wt is transmitted in step S93. After outputting to the transmission circuit 34, the process returns to step S81. As described above, since the forwarding standby time Wt is extended according to the state of the surrounding traffic, step S103 is provided in order to perform the reverse process.

As can be seen from the above description, the wireless communication system of this embodiment is a system for transmitting packet signals in a broadcast system. The number of remaining hops indicating the number of terminals, that is, the number of times of forwarding is set. If the number of remaining hops included in the received packet signal indicates a numerical value equal to or more than “1”, each wireless communication terminal resets the numerical value obtained by subtracting “1” from this numerical value to the packet signal as the number of remaining hops, Forwards packet signals. On the other hand, if the remaining hop number of the received packet signal is “0”, the forwarding is stopped. As described above, since the broadcast method is adopted for packet communication, and each wireless communication terminal stops forwarding according to the number of remaining hops, a packet signal can be transmitted over a wide range without increasing transmission power as in the related art. The transmission range can be easily controlled by the number of remaining hops.

In this embodiment, the error rate of the received packet signal is evaluated, and the forwarding standby time is determined according to the evaluation value. Here, the determined forwarding standby time becomes longer as the error rate becomes lower. For example, a packet signal received from a distant wireless communication terminal is more preferentially forwarded. However, if traffic is congested, the forwarding waiting time is extended. For this reason, the packet signal is transmitted when there is enough traffic.

Each packet signal has a different sequence number for each packet. Each wireless communication terminal has a case where the sequence number included in the currently received packet signal matches the sequence number included in the packet signal waiting for forwarding and the error rate when the packet signal waiting for forwarding is received is low. Then, the forwarding of the packet signal waiting for forwarding is stopped. The packet signal having a low error rate is considered to have been transmitted from a wireless communication terminal at a relatively short distance, and by stopping the forwarding of such a packet signal,
Traffic congestion is reduced.

Further, each wireless communication terminal invalidates the currently received packet signal when the sequence number included in the currently received packet signal matches the sequence number included in the previously received packet signal. Since neither output processing nor forwarding processing is required for the same packet signal as the packet signal received in the past,
Such a packet signal is invalidated.

The packet signal specifically includes a broadcast packet transmitted through a broadcast channel, and a container packet transmitted through any one of a plurality of container channels. further,
The broadcast packet has container channel information indicating the transmission channel of the related container packet. Therefore, each wireless communication terminal first receives a broadcast packet through a broadcast channel, and detects container channel information from the received broadcast packet. Then, the receiving channel is switched to the channel indicated by the container channel information. As described above, since the container packet including the content information is transmitted through any one of the plurality of container channels, traffic congestion is reduced. Further, since the broadcast packet transmitted in advance includes the container channel information, the subsequent container packet can be reliably received.

Further, each radio communication terminal stores the container channel information detected from the received broadcast packet in a memory, and selects a channel having low correlation with the channel indicated by the container channel information as a container channel for forwarding. . For this reason, each container channel can be prevented from being congested.

In this embodiment, step S in FIG.
As shown in FIG. 99, whether to stop forwarding the packet signal is determined based on the error rate when the packet signal waiting is received. The determination may be made based on the output of the reception power measurement circuit 22 at the time of reception. That is, since it is possible to determine whether the packet signal has been successfully received based on the received power (received signal level), the process proceeds to step S101 if the received power is large and proceeds to step S103 if the received power is small in step S99. You may do so.

Whether or not to stop the forwarding may be determined based on whether or not the condition shown in Expression 2 is satisfied. That is, if Equation 2 is satisfied, step S1
01, and if Expression 2 is not satisfied, step S103
You may make it go to.

[0062]

## EQU2 ## Wt> Tw and Rnd (C) ≦ Rr Wt: Forwarding standby time Tw: Reference value C: Predetermined value Rnd (C): Arbitrary value taking a value less than C Rr: Arbitrary value satisfying Rr <C For example, if Rnd (C) is “1”, “2”, “3”,
When Rr takes "4", taking either "4" or "5", the condition of Rnd (C) ≤Rr is satisfied with an 80% probability. On the other hand, Wt> Tw is satisfied when the error rate at the time of reception of a waiting packet signal is low or when traffic is congested. For this reason, when the error rate at the time of reception of the waiting packet signal is low or the traffic is congested, the forwarding is stopped with a probability of 80%.
That is, when each wireless communication terminal makes a similar forwarding stop determination, only one out of five wireless communication terminals that satisfies the condition of Wt> Tw forwards a waiting packet signal.

Further, when the number of times of receiving the same packet signal (both the number of remaining hops and the sequence number match) as the packet signal in standby exceeds a predetermined value, the forwarding of the packet signal in standby is stopped. It may be.
Such a situation occurs when there are many wireless communication terminals in the vicinity, and a packet signal having the same remaining hop number and sequence number is forwarded by the surrounding wireless communication terminals, thereby preventing traffic congestion. The forwarding is stopped as much as possible.

In this embodiment, step S in FIG.
91 and S93, the forwarding standby time Wt
Is calculated based on the error rate evaluation value Eg, but the forwarding standby time Wt may be calculated based on the output of the received power measurement circuit.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention.

FIG. 2A is an illustrative view showing one example of a broadcast packet, and FIG. 2B is an illustrative view showing one example of a container packet;

FIG. 3 is an illustrative view showing one example of a used channel history memory;

FIG. 4 is an illustrative view showing one example of a sequence number memory;

FIG. 5 is a flowchart showing a part of the operation of the packet transmission circuit.

FIG. 6 is a flowchart showing a part of the operation of the packet assembling circuit.

FIG. 7 is a flowchart showing a part of the operation of the transmission channel control circuit.

FIG. 8 is a flowchart showing a part of the operation of the CPU;

FIG. 9 is an illustrative view showing one portion of an operation of each wireless communication terminal included in the wireless communication system;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 12 ... Packet reception circuit 14 ... Packet analysis circuit 16 ... Transmission channel control circuit 20 ... Reception channel control circuit 24 ... Error rate analysis circuit 30 ... CPU 34 ... Packet transmission circuit 36 ... Packet assembly circuit

Continued on the front page F term (reference)

Claims (8)

[Claims] 1. A wireless communication system for transmitting a packet signal to a plurality of wireless communication terminals by a broadcast method, wherein the packet signal includes a numerical value indicating the number of times of transmission of the packet signal, and each of the wireless communication terminals Receiving means for receiving a signal from another of the wireless communication terminals; numerical value comparing means for comparing the numerical value included in the packet signal received by the receiving means with a predetermined value; Updating means for updating the numerical value, forwarding means for forwarding the packet signal including the numerical value updated by the updating means to another wireless communication terminal, and when the comparison result of the numerical value comparing means indicates a match, A wireless communication system comprising first disabling means for disabling a forwarding means. 2. Each of the wireless communication terminals includes: a first detection unit that detects a reception state or a reception power of the packet signal received by the reception unit; and the reception state that is detected by the first detection unit. 2. The wireless communication system according to claim 1, further comprising a determination unit configured to determine a forwarding standby time of the packet signal based on the received power, wherein the forwarding unit performs forwarding when the forwarding standby time has elapsed. 3. The wireless communication system according to claim 2, wherein said determining means makes said forwarding standby time longer as said reception condition becomes better or said reception power becomes larger. 4. Each of the wireless communication terminals further comprises traffic discriminating means for discriminating a traffic congestion state, and extending means for extending the forwarding standby time according to the discrimination result of the traffic discriminating means. 4. The wireless communication system according to 2 or 3. 5. Each of the packet signals includes a different identifier for each packet, each of the wireless communication terminals includes: a second detector for detecting the identifier from the packet signal received by the receiver; First identifier comparing means for comparing the identifier included in the packet signal in the packet with the identifier detected by the second detecting means, the reception state or the reception power when the packet signal waiting for forwarding is received 5. The apparatus according to claim 2, further comprising: a determination unit configured to determine whether the forwarding is performed, and a second disable unit configured to disable the forwarding unit in accordance with a comparison result of the first identifier comparison unit and a determination result of the determination unit. A wireless communication system according to claim 1. 6. Each of the packet signals includes content information and an identifier which are different for each packet, and each of the wireless communication terminals decodes the content information included in the packet signal received by the receiving means. Means, third detecting means for detecting the identifier from the packet signal received by the receiving means, second identifier comparing means for comparing the identifier detected by the third detecting means with the previously detected identifier 5. The wireless communication system according to claim 1, further comprising a third disabling means for disabling said decoding means when a comparison result of said second identifier comparing means indicates a match. 7. The packet signal includes a first packet signal transmitted through any one of a plurality of channels, and a channel having channel information of the first packet signal and passing through a specific channel prior to the first packet signal. A second packet signal to be transmitted, wherein the receiving unit detects channel information from the second packet signal received through the specific channel, and the channel detected by the channel information detecting unit. 2. A channel switching means for switching a reception channel based on information.
7. The wireless communication system according to any one of claims 6 to 6. 8. Each of the radio communication terminals includes a memory for storing the channel information detected by the channel information detecting means, and a channel having low correlation with the channel indicated by the channel information stored in the memory. The wireless communication system according to claim 7, further comprising a forwarding channel determination unit that determines a forwarding channel of the first packet signal.