JP2004282492A - Communication method and system thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and a system for securely transferring packetized data to another communication system in a network, by minimum transmitting/receiving operation. <P>SOLUTION: When packetized data are transmitted in a network composed of a plurality of communication systems, at least one communication station in the network transmits the packet data at a random interval using a predetermined frequency band. When the packet data are transmitted, information on time to transmit the following packet data is added to the packet data to be transmitted. Information on a frequency hopping pattern is also added as the need arises. For each communication system in the network, transmitting/receiving timing or a frequency can be set based on the time information contained in the packet data. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a communication method suitable for performing data communication by transferring packets in a wireless communication network including, for example, a plurality of communication devices, and a communication device to which the communication method is applied.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, when two-way wireless communication is performed between a plurality of communication devices, for example, a certain transmission band (channel) is occupied by two communication devices, and the occupied transmission band is used. The communication from one communication device to the other communication device and the communication to the other communication device are continuously and alternately performed, or two channels are occupied and one channel is used for one communication device. It is the simplest communication process to use the communication from the communication device to the other communication device and use the other channel for the communication in the opposite direction.
[0003]
Performing such two-way wireless communication by occupying the transmission band for a long time is inefficient in the use of the transmission band. For example, when a large number of wireless communication devices exist in one wireless communication network, each wireless communication In the case where there is a transmission start request between the apparatuses, unless a large number of transmission channels are prepared, all communication start requests in the network cannot be satisfied.
[0004]
For this reason, for example, various communication systems have been developed in which data to be transmitted is packetized and a prepared transmission band is used for a short period only while the packet is being transmitted. By transmitting the packetized data for a short period of time, one transmission band can be shared by a plurality of communication devices in a network as long as transmission of packets does not overlap with other communication devices, and transmission efficiency is improved. high.
[0005]
For example, Bluetooth (trademark) disclosed in Non-Patent Document 1 and the like has been put to practical use as a system capable of constructing an advanced wireless communication system by transferring packetized data.
[0006]
[Non-patent document 1]
Kazuhiro Miyazu "Bluetooth Guidebook" August 28, 2000 Published by Nikkan Kogyo Shimbun, pages 153 to 164
[0007]
[Problems to be solved by the invention]
By the way, for example, in a wireless communication system that performs packet transfer such as the Bluetooth system, even if the packet transfer is performed, basically, there is no idle time while each communication device is performing wireless communication, and when data is transferred. Since the communication is established and waiting in the network so as to be able to receive even if received, each communication device has a problem that power consumption cannot be reduced so much. For example, in the case of the Bluetooth system, it is possible to shift to an operation mode called a sniff mode in order to set an idle time for temporarily stopping transmission or reception in order to perform low power consumption operation. However, the sniff mode is a mode in which only a communication device of a type called a slave can shift, and a communication device performing a control operation called a master cannot shift to such a low power consumption mode. In addition, the sniff mode is a mode in which when communication is temporarily stopped, the minimum communication is performed for the purpose of maintaining synchronization in the network, etc., and the power consumption during steady wireless communication is reduced. It is not intended.
[0008]
Therefore, in the conventional communication method for performing packet transfer, there is a limit in reducing power consumption of each communication device. Here, the wireless transmission such as the Bluetooth system has been described as an example. However, in the case of the communication system in which packet transfer is performed, there is a similar problem regarding low power consumption even in the case of wired transmission. That is, conventionally, when transferring packetized data in a network, regardless of whether it is wireless or wired, a certain synchronization timing is set in the network and a packet is transmitted based on the synchronization timing. I was trying to do it.
[0009]
An object of the present invention is to make it possible to reliably transfer packetized data with another communication device in a network with minimum transmission and reception operations.
[0010]
[Means for Solving the Problems]
According to the present invention, when packetized data is transmitted in a network composed of a plurality of communication devices, at least one communication station in the network uses a predetermined frequency band to perform randomization. When packet data is transmitted at time intervals and the packet data is transmitted, information relating to the next packet data transmission time is added to the packet data to be transmitted.
[0011]
By doing so, the communication device that has received the packet data can determine, from the information included in the packet data, the timing at which the receiving operation is to be performed to receive the next packet data. The operation can be stopped.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.
[0013]
A configuration example of a network system to which the present invention is applied will be described with reference to FIG. In this example, a network is configured by a plurality of wireless communication terminals 10a, 10b, 10c # each configured as a wireless communication device, and among the wireless communication terminals 10a to 10e in the network, The configuration is such that packet data is transferred by wireless transmission to each other, and bidirectional communication is possible. FIG. 1 is an example of a network configuration, and a network basically including any number of wireless communication devices may be used as long as a plurality of wireless communication devices are provided.
[0014]
FIG. 2 is a diagram illustrating a configuration example of a wireless communication terminal 10 as a wireless communication device. To explain the configuration, as the transmission processing configuration, the transmission data obtained by the upper layer processing unit 11 is supplied to the signal processing unit 12, and the signal processing for transmission is performed to obtain packet data for transmission. The packet data for transmission is temporarily stored in the buffer 13 and then supplied to the modulation / demodulation unit 14 to perform modulation processing for transmission at the timing of transmission, and the modulated transmission packet is transmitted to the high frequency unit (RF (Section 15), a signal having a predetermined transmission frequency is transmitted, and transmitted from the antenna 16 by radio. The setting of the transmission frequency in the high-frequency unit 15 is set by the control in the frequency switching control unit 19 based on the instruction from the control unit 17.
[0015]
In the case of this example, the time information and the frequency hopping information are sent from the time / frequency hopping information storage unit 18 to the signal processing unit 12 under the control of the control unit 17 during the transmission processing of the packet data. Contains time information and frequency hopping information. The details of the time information and the frequency hopping information will be described later.
[0016]
As a reception processing configuration, a reception processing of a signal of a predetermined frequency is performed in the high frequency unit 15 to which the antenna 16 is connected. The reception frequency is set by the control of the frequency switching control unit 19 based on a command from the control unit 17. The received signal output by the high-frequency unit 15 is supplied to the modulation / demodulation unit 14 to perform demodulation processing, and the data of the demodulated received packet is supplied to the signal processing unit 12 via the buffer 13 so that the data included in the received packet is transmitted. This is supplied to the upper layer processing unit 11. Further, control information, particularly time information and frequency hopping information, included in the received packet is stored in a time / frequency hopping information storage unit 18 so that the control unit 17 can determine the stored information.
[0017]
Next, a process of wirelessly transmitting packet data in a network configured by preparing a plurality of wireless communication terminals 10 configured as described above will be described. In this example, as a channel (frequency band) for performing wireless transmission, a channel for steady operation and an individual communication channel are prepared. A communication terminal that does not have a communication request performs communication on a steady operation channel, and when a communication request is made, shifts to communication on an individual communication channel to perform communication.
[0018]
Further, in the case of this example, when communicating with other terminals in the network, time hopping processing and frequency hopping processing are performed as necessary. Here, the time hopping process is a process of changing a time interval for transmitting packet data every time one packet is transmitted, and a pattern to be changed is determined by a hopping sequence. The frequency hopping process is a process of changing the frequency to be transmitted every time one packet is transmitted. Regarding the frequency hopping, the pattern to be changed is determined based on the random number information in the hopping sequence. For the time hopping and the frequency hopping, both patterns may be designated by one piece of random number information, or they may be designated by individual pieces of random number information. In the case of this example, each channel is a channel having a relatively narrow frequency bandwidth.
[0019]
First, an example of processing in a steady communication channel will be described with reference to the flowchart in FIG. When the communication terminal starts communication on the steady communication channel based on the control of the control unit 17 (step S11), information indicating the time hopping sequence currently set for this terminal is transmitted on the steady communication channel. The transmission processing of the packet is performed by including the packet in the packet to be transmitted (step S12). In the case of this example, immediately after the transmission of the packet, the reception of the packet transmitted from another terminal is tried for a predetermined period (step S13), and the control unit 17 determines that the reception of the packet is not performed during the reception period. It is determined whether or not the operation has been completed (step S14).
[0020]
If the packet cannot be received, a time and a frequency for transmitting the next packet data are set based on the sequence of the time hopping and the frequency hopping currently set for the terminal (step S18). Wait for packet data transmission.
[0021]
Then, in step S14, when a packet from another terminal has been received, it is determined whether or not the received packet includes a communication request to start communication with the terminal (step S15). Here, when it is determined that there is no communication request, when the packet received at that time contains random number information, the reception timing and the received random number information are stored in the storage unit 18 as information of the received terminal. The packet information is stored, the terminal information is updated (step S16), the process proceeds to step S18, the time and frequency for transmitting the next packet data are set, and the process waits until the next packet data is transmitted.
[0022]
Further, in step S15, when it is determined that there is a communication request to start communication with the terminal, the process shifts to communication processing on the individual communication channel specified by the communication request (step S17), and the communication processing is performed on the individual communication channel. Then, the time and frequency for transmitting the next packet data are set (step S18), and the process waits until the next packet data is transmitted.
[0023]
Next, an example of processing in a case where each communication terminal transmits a communication request using the channel for steady operation will be described with reference to the flowchart in FIG. First, when there is a communication start request (step S21), the control unit 17 determines the timing at which the partner terminal receives a signal from the random number information of the partner terminal requesting the communication (step S22). Then, a transmission request packet containing information on the individual communication channel to be used is generated and transmitted at a timing when the terminal of the other party receives the packet (step S23). A reception confirmation packet indicating that the transmitted packet has been received is generated. It is determined whether or not the reception was successful (step S24). If the reception confirmation packet indicating that the packet has been received is successfully received, the transmission on the dedicated communication channel is continued (step S26). If the reception confirmation packet cannot be received in step S24, the transmission on the individual communication channel here is stopped (step S25).
[0024]
Next, an example of a process when each communication terminal receives a communication request on a channel for steady operation will be described with reference to a flowchart of FIG. When a packet including a communication request with the communication terminal is received (Step S32) in a state where the steady operation channel is received (Step S31), packet data is received on the individual communication channel indicated by the communication request packet (Step S32). In step S33, a reception confirmation packet indicating that the data has been received is transmitted (step S34), and reception on the dedicated communication channel is continued (step S35).
[0025]
FIGS. 6 and 7 are flowcharts showing an example of a communication operation of each communication terminal on an individual communication channel. First, the operation of the terminal, which has transmitted the communication request, on the individual communication channel will be described with reference to FIG. 6. When the operation shifts to the operation on the individual communication channel (step S41), the operation proceeds to A packet containing data to be actually transmitted is transmitted (step S42), and immediately after that, a packet receiving process is performed on the same dedicated communication channel (step S43). It waits until the transmission timing (step S44). The reception confirmation packet of the packet transmitted in step S42 is received in step S43.
[0026]
FIG. 7 shows the operation of the terminal receiving the communication request on the individual communication channel. When the operation shifts to the dedicated communication channel (step S51), a packet is received on the dedicated communication channel designated by the regular operation channel (step S52). Immediately after that, data to be transmitted using the same dedicated communication channel is received. Is transmitted (step S53). At the time of packet transmission in step S53, control data such as reception confirmation data is also transmitted at the same time. Thereafter, the frequency for transmission and reception is switched, and the system waits until the next transmission timing (step S54).
[0027]
In the communication processing up to this point, in the steady operation channel, the instruction to shift to the individual communication channel is given to the terminal that transmits the communication request packet, but conversely, the terminal that receives the communication request packet is An instruction to shift to an individual communication channel may be issued. In this case, the flowchart of FIG. 6 is the processing at the terminal that has received the communication request, and the flowchart of FIG. 7 is the processing at the terminal that has transmitted the communication request.
[0028]
Next, an example of an operation of a terminal until a communication request packet is transmitted in a steady operation channel will be described with reference to a flowchart of FIG. When the processing here starts (step S61), first, a packet from another terminal is received on the steady operation channel and its existence is found (step S62). At this time, the random number information included in the received packet is stored in the storage unit 18 in the terminal, and the control unit 17 can know at what time the terminal will transmit in the future (step S63). This information storage needs to be updated as appropriate in consideration of clock errors between terminals and the like. In this updating process, a packet transmitted by the other party may be received while the clock error between the terminals is sufficiently small, and an error from the assumed timing may be measured.
[0029]
After accumulating the terminal information in this way, when it is necessary to actually transmit data to another terminal (step S64), the time at which the other terminal performs transmission / reception is calculated or referred to (step S65). The communication request packet is transmitted at an appropriate timing (step S66).
[0030]
Next, a state in which the communication processing of this example is actually performed will be described with reference to timing charts in FIG. 9 and subsequent figures. FIG. 9 is a diagram showing a transmission / reception operation in a steady operation channel. Here, two channels of a channel 1 (FIG. 9A) and a channel 2 (FIG. 9B) are prepared as the normal operation channels, and the two channels are used alternately. . First, as shown in FIG. 9A, a transmission Tx of a packet for a relatively short period (for example, 2 msec) on channel 1 and a transmission for a period slightly longer than the transmission (for example, 4 msec) following the transmission. The reception Rx is performed as one unit of transmission / reception processing P11. Then, after the transmission / reception process P11, after a period set at random within a predetermined range based on the random number information, as shown in FIG. Tx and the reception Rx for a slightly longer period of time following the transmission are performed as one unit of transmission / reception processing P12. Hereinafter, as long as the process in the steady operation channel continues, the communication at the randomly set time interval is continued.
[0031]
As the communication interval set at random, for example, as shown in FIG. 10, a value set by the random number value Rnd is set in a range from 750 ms to 1250 ms. Here, the transmission Tx of the packet is performed in 2 ms, and the subsequent reception Rx is performed in 4 ms. For example, as shown in FIG. After the execution, a time set in the range of 750 ms to 1250 ms based on the random number value Rnd elapses, and one unit of transmission / reception processing P22 in channel 2 is performed. In this case, the packet transmitted at the time of transmission / reception processing P21 includes random number information or information about a sequence that determines the random number.
[0032]
FIG. 11 is a diagram illustrating an example of a transmission / reception state in an individual communication channel. First, as shown in FIG. 11A, when a communication start request with this terminal is received at the time of performing transmission / reception processing P31 on the steady operation channel, a plurality of terminals are prepared as shown in FIG. 11B. The transmission / reception process P32 is performed by shifting to the channel included in the communication start request among the individual communication channels, and the transmission / reception process P33, P34 # by changing the communication channel is performed. Two-way communication is performed by transmitting and receiving packet data in a state where frequency hopping is performed.
[0033]
FIG. 12 is a diagram showing an example of the details of the communication processing of FIG. As shown in FIG. 12A, communication is performed during a reception period in a state where transmission P41 of a packet at 2 ms in a channel for a steady operation and reception P42 of 4 ms immediately thereafter are performed. It is assumed that a packet P43 including a start request is received. At this time, as shown in FIG. 12 (b), it shifts to the individual communication channel designated by the request, and after 6 ms from the reception of the request packet P43, the transmission P44 of the packet in 2 ms and the immediately following 2 ms As shown in FIG. 12 (c), as long as communication continues, the packet is transferred to another individual communication channel and transmission / reception of the packet is performed 6 ms later.
[0034]
In the example of FIG. 12, only the frequency hopping for switching the communication channel is performed, and the interval for each unit of transmission / reception is fixed to the interval of 6 msec. As described above, time hopping in which the time interval is changed within a certain range based on the random number value may be performed. Alternatively, only time hopping may be performed, and the individual communication channel may be fixed.
[0035]
FIG. 13 is a diagram illustrating an example of a format of a transmission packet in a steady operation channel. As shown in FIG. 13A, the physical packet P51 transmitted at one time on the steady operation channel is a packet in which 20 bits are arranged, and the 20-bit data is, as shown in FIG. For example, it is composed of a MAC layer packet P52 of 12 bits, and a CRC (Cyclic Redundancy Check) code P53 which is error correction information of 8 bits. The MAC layer packet P52 is converted into a physical packet P51 by performing, for example, an interleaving process (that is, a replacement of bit positions).
[0036]
FIG. 14 is a diagram illustrating an example of a transmission packet on an individual communication channel. FIG. 14B shows a MAC layer packet P62 transmitted on the dedicated communication channel. The MAC layer packet P62 is a packet P61 (FIG. 13) on the steady operation channel shown in FIG. (Same as the packet P51 in (a)) as a data configuration of the number of bits obtained by collecting 20 bits. The MAC layer packet P62 transmitted on the dedicated communication channel is divided into a header part P63 and a data part (payload) P64 as shown in FIG. Is also arranged.
[0037]
FIG. 15 is a diagram illustrating an example of a random number table used for time hopping in a steady operation channel. All terminals in the network system use the same random number sequence, and what is transmitted on the steady operation channel is the random number used at that time. The terminal that receives it can calculate the subsequent transmission timing of the receiving terminal with reference to the random number table as shown in FIG. 15, and similarly obtain the transmission timing of its own station.
[0038]
As described above, time hopping is performed on the steady operation channel and, if necessary, frequency hopping is also performed. Therefore, even if there is no transmission of synchronous data in the network on the steady operation channel, any time in the network can be obtained. Communication with the terminal can be started. If each terminal in the network performs a receiving operation continuously for a relatively long time, for example, for a while after the power is turned on, the timing at which the terminal in the network transmits a packet on a steady operation channel Thus, even if time hopping has been performed, it is possible to set to receive packets from each terminal. Therefore, each terminal in the network only needs to perform transmission and reception in an intermittent operation while performing time hopping, which contributes to a reduction in power consumption of a wireless communication device constituting the terminal. In addition, since time hopping is performed based on a random value, the possibility of collision of packet transmissions in a steady operation channel is averaged, and as a result, the possibility of packet collision is minimized. And good two-way communication can be performed on the steady operation channel.
[0039]
In the case of this example, in the steady operation channel, as shown in FIG. 13, for example, a packet transmitted using 2 ms is a packet of a relatively low bit rate of about 20 bits. Wireless communication is possible, and even when a relatively large number of terminals form a network in a relatively wide range, communication control within the network can be reliably performed.
[0040]
In the above-described embodiment, the packet configuration illustrated in FIG. 13 and the like is an example, and the present invention is not limited to this packet configuration.
[0041]
Further, in the above-described embodiment, the case of a network configuration for performing wireless communication has been described.For example, in a network connected by a wired bus line, a similar steady operation channel and an individual communication channel are prepared. Communication processing in each channel may be performed by similar processing.
[0042]
Further, in the above-described embodiment, the wireless communication device having the configuration shown in FIG. 2 is prepared, and the above-described process is performed by the communication device. The program may be stored and distributed to a user, and the user may install the program in a computer device or the like, and incorporate a card or board for performing data communication operation into the computer device to execute a similar function. good.
[0043]
【The invention's effect】
According to the present invention, the communication device that has received the transmitted packet data can determine from the information included in the packet data the timing of performing a reception operation for receiving the next packet data. The operation can be stopped. Therefore, even in a network where there is no communication device as a master for setting the synchronization timing, each communication device in the network can perform intermittent communication operation, and can efficiently transfer packet data. Having.
[0044]
In this case, by preparing a plurality of frequency bands as frequency bands and adding information on the frequency band for transmitting the packet data to the packet data, it is possible to cope with the case where a plurality of transmission frequencies are prepared.
[0045]
Further, the information on the frequency band for transmitting the packet data is information on frequency hopping for switching the frequency band when transmitting a plurality of packet data. Learn from the data.
[0046]
In addition, since transmission is attempted for a predetermined period in the transmitted frequency band after transmission of packet data, transmission and reception can be performed almost at the same time, and intermittent operation of transmission and reception can be reduced in power consumption. It can be done with appropriate and effective timing settings.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating a system configuration example according to an embodiment of the present invention.
FIG. 2 is a block diagram illustrating an example of a terminal configuration according to an embodiment of the present invention.
FIG. 3 is a flowchart showing an example of transmission / reception processing in a channel for steady operation according to an embodiment of the present invention.
FIG. 4 is a flowchart illustrating a processing example when a communication request is transmitted on a channel for steady operation according to an embodiment of the present invention.
FIG. 5 is a flowchart illustrating a processing example when a communication request is received on a channel for steady operation according to an embodiment of the present invention.
FIG. 6 is a flowchart showing an example of a data transmission / reception operation (an example of processing in a terminal that has transmitted a communication request) on an individual communication channel according to an embodiment of the present invention.
FIG. 7 is a flowchart illustrating an example of a data transmission / reception operation (an example of processing in a terminal that has received a communication request) on an individual communication channel according to an embodiment of the present invention.
FIG. 8 is a flowchart illustrating an example of a communication request transmission operation in a steady operation channel according to an embodiment of the present invention.
FIG. 9 is a timing chart showing an example of transmission / reception timing in a steady operation channel according to an embodiment of the present invention.
FIG. 10 is a timing chart showing a more detailed example of transmission / reception timing in a steady operation channel according to an embodiment of the present invention.
FIG. 11 is a timing chart showing an example of transmission / reception timing in an individual communication channel according to an embodiment of the present invention.
FIG. 12 is a timing chart showing a more detailed example of transmission / reception timing in an individual communication channel according to an embodiment of the present invention.
FIG. 13 is an explanatory diagram showing an example of a packet configuration in a steady operation channel according to an embodiment of the present invention.
FIG. 14 is an explanatory diagram showing an example of a packet configuration in an individual communication channel according to an embodiment of the present invention.
FIG. 15 is an explanatory diagram showing an example of a random number table used for time hopping in a steady operation channel according to an embodiment of the present invention.
[Explanation of symbols]
10, 10a to 10e: wireless communication terminal, 11: upper layer processing unit, 12: signal processing unit, 13: battery, 14: modulation / demodulation unit, 15: RF unit, 16: antenna, 17: control unit, 18: time Frequency hopping information storage

Claims (12)

In a communication method for transmitting packetized data in a network composed of a plurality of communication stations,
At least one communication station in the network transmits packet data at random time intervals using a determined frequency band,
A communication method in which when transmitting the packet data, information relating to a time when the next packet data is transmitted is added to the packet data to be transmitted. The communication method according to claim 1,
A communication method in which a plurality of frequency bands are prepared as the frequency band, and information on a frequency band for transmitting the packet data is also added to the packet data. The communication method according to claim 1,
The communication method, wherein the information on the frequency band for transmitting the packet data is information on frequency hopping for switching a frequency band when transmitting a plurality of packet data. The communication method according to claim 1,
A communication method in which, after transmission of the packet data, reception is attempted for a predetermined period in the transmitted frequency band. The communication method according to claim 4,
A communication method for setting a timing for receiving the next packet data based on information included in the received packet data and for transmitting the next packet data when receiving the packet data in the reception for the predetermined period. The communication method according to claim 5,
When the received packet data includes information on a frequency band for transmitting the next packet data, a communication method for switching to reception at a corresponding band frequency. In a communication device for transmitting packetized data to and from another communication device,
Communication means for transmitting and receiving in a predetermined frequency band,
Using the determined frequency band, the communication means causes packet data to be transmitted at random time intervals, and when transmitting the packet data, information relating to the next packet data transmission time is included in the packet data. A communication device provided with a control unit to be added. The communication device according to claim 7,
The frequency band in which the communication unit performs transmission and reception is a frequency band selected from a plurality of frequency bands prepared in advance, and the control unit transmits packet data transmitted by the communication unit, A communication device in which information about a frequency band for transmitting a packet is also added. The communication device according to claim 7,
The communication device, wherein the information about the frequency band for transmitting packet data added by the control means is information about frequency hopping for switching frequency bands when transmitting a plurality of packet data. The communication device according to claim 7,
The communication device, wherein the control unit controls transmission of the packet data by the communication unit, and then causes the communication unit to attempt reception for a predetermined period in the transmitted frequency band. The communication device according to claim 10,
When packet data is received by the communication unit during the reception attempt, the control unit determines the next packet data in the communication unit based on information on the next packet data transmission time included in the received packet data. A communication device for setting the timing for receiving the packet data. The communication device according to claim 11,
Further, when the packet data received by the communication unit includes information on a frequency band for transmitting the next packet data, the control unit controls the communication unit to perform control for switching to reception at a corresponding band frequency. apparatus.

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