JP2006115084A - Communication apparatus and method, and communication system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To avoid collision against other system at high speed when data is transmitted/received by wireless communication using a frequency hopping system. <P>SOLUTION: A communication master 10 and a communication slave 20 previously hold a list where a plurality of frequency channels are divided to a plurality of tables for each of a predetermined number of continuous frequency channels, and transmit/receive data while altering the frequency channel in a sequence according to that list. When there is no interference with other communication system, hopping is performed using all frequency channels on all tables. The communication master 10 determines the proportion of frequency channels where a packer error has occurred for each table and makes a table unavailable when the proportion exceeds a threshold. When taking a round of all tables available of the frequency channel, information of availability of each table is notified to the communication slave 20. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a communication system that transmits and receives data by wireless communication while hopping a frequency channel to be used, and a communication apparatus and method used in such a communication system.

  In recent years, digital wireless transmission equipment using a wireless local area network (LAN) or the like has been continuously developed. Actually, not only a PC (Personal Computer) but also various devices such as a PDA (Personal Digital Assistant), a television device, and an audio device are equipped with a wireless function. In addition, in the 2.4 GHz band, which is one of the ISM (Industry Science Medical) bands that can be used without a license, international standards such as IEEE802.11b / g and Bluetooth have been established, and many products comply with these standards. It has been released.

  By the way, in a communication band in which a plurality of communication methods coexist, the fact that wireless devices of different communication methods interfere with each other is an important problem in the present day when wireless devices are becoming popular.

  Therefore, for example, in the Bluetooth standard described above, in order to avoid interference with a communication system of another communication method, an AFH (Adaptive Frequency) in which frequency channels occupied by other communication systems are avoided and hopping is performed using available frequency channels. Hopping) function. Patent Document 1 listed below discloses a technique for notifying a communication slave of a frequency channel that cannot be used for communication, for example, from a communication master.

JP 2002-368654 A

  However, in the Bluetooth standard AFH and the technology described in Patent Document 1, whether or not the frequency channel can be used is managed in units of frequency channels. Therefore, in a device or system operating with a low-speed clock, other communication methods are used. There is a problem that it is difficult to immediately determine whether or not the communication system of FIG.

  The present invention has been proposed in view of such conventional circumstances, and can perform collision avoidance with other communication systems at high speed when transmitting and receiving data by wireless communication using a frequency hopping method. An object of the present invention is to provide a possible communication system, and a communication apparatus and method used in the communication system.

  In order to achieve the above-described object, a communication apparatus according to the present invention is a communication apparatus that communicates with one or more other communication apparatuses while sequentially changing a plurality of frequency channels. A communication means for holding a list obtained by dividing the plurality of frequency channels into a plurality of tables for each frequency channel, and transmitting / receiving data while changing the frequency channel in an order according to the list, and communication from the plurality of frequency channels to the communication A table classification unit that detects a frequency channel that cannot be used and classifies a table in which a ratio of frequency channels that cannot be used for the communication exceeds a predetermined threshold as an unusable table, and the communication unit includes an available table. And / or notify the other communication device of information on the unusable table and include it in the usable table. A frequency channel that transmits and receives data while changing the order in accordance with the above list.

  In order to achieve the above-described object, a communication method according to the present invention is a communication method for communicating with one or more other communication devices while sequentially changing a plurality of frequency channels. A communication step of holding a list obtained by dividing the plurality of frequency channels into a plurality of tables for each number of frequency channels, and transmitting and receiving data while changing the frequency channels in an order according to the list, and from the plurality of frequency channels A table classification step of detecting a frequency channel that cannot be used for communication and classifying a table in which the ratio of frequency channels that cannot be used for communication exceeds a predetermined threshold as an unusable table. Information on possible tables and / or unavailable tables is notified to the other communication devices, and usable tables The frequency channels included in transmit and receive data while changing the order in accordance with the above list.

  In order to achieve the above-described object, the communication system according to the present invention maintains a list obtained by dividing a plurality of frequency channels into a plurality of tables for each predetermined number of consecutive frequency channels, and an order according to the list. The communication system for transmitting and receiving data between the first communication device and the one or more second communication devices while changing the frequency channel in the first communication device, wherein the first communication device uses the plurality of frequency channels. A frequency channel that cannot be used for communication is detected, a table in which the ratio of frequency channels that cannot be used for communication exceeds a predetermined threshold is classified as an unusable table, and an available table and / or an unusable table. Information is sent to the one or more second communication devices, and the first communication device and the one or more second communication devices can be used. The frequency channels included in Buru to transmit and receive data while changing the order in accordance with the above list.

  According to the communication device, the method thereof, and the communication system according to the present invention, when communication is performed between a plurality of communication devices while sequentially changing a plurality of frequency channels, whether or not the frequency channels can be used is determined on a frequency channel basis. Since a plurality of frequency channels are managed in units of tables, collision avoidance with a communication system of another communication method can be performed at high speed.

  Hereinafter, specific embodiments to which the present invention is applied will be described in detail with reference to the drawings. In this embodiment, when data is transmitted / received by wireless communication in the 2.4 GHz band, which is one of the ISM bands, using the frequency hopping method, the present invention avoids collision with a communication system of another communication method. The present invention is applied to a communication system capable of performing at high speed, a communication device (communication master) used in the communication system, and a communication method thereof.

  First, a schematic configuration of a communication system in the present embodiment is shown in FIG. As shown in FIG. 1, in the communication system 1 according to the present embodiment, for example, one communication master 10 that is a music playback device and one communication slave 20 that is a wireless headphone with a remote controller, for example, exchange data with each other. Send and receive.

  The communication master 10 roughly includes a main system 11 and a wireless unit 12. Among them, the radio unit 12 includes a ROM (Read Only Memory) 13 that is a nonvolatile storage medium, a RAM (Random Access Memory) 14 that is a volatile storage medium, a baseband processing unit 15, and an RF (Radio Frequency) process. The unit 16 and the antenna 17 are included. Similarly, the communication slave 20 roughly includes a main system 21 and a wireless unit 22, and the wireless unit 22 includes a ROM 23, a RAM 24, a baseband processing unit 25, an RF processing unit 26, and an antenna 27. Become. For example, the communication master 10 modulates the music signal compressed and encoded by the main system 11 by the radio unit 12 and mixes it with the carrier wave and transmits it. On the other hand, the communication slave 20 receives and demodulates the signal by the wireless unit 22, decodes and decompresses it by the main system 21, and outputs it from a speaker (not shown). The communication slave 20 modulates an acknowledge signal, a remote controller control signal, and the like by the wireless unit 22, mixes it with a carrier wave, and transmits it to the communication master 10.

  Here, the communication master 10 and the communication slave 20 each transmit one packet of data per unit time. At this time, the communication master 10 and the communication slave 20 hop the frequency of the carrier wave used for data transmission. That is, in one data transmission / reception per unit time, different carrier frequencies are used for transmission from the communication master 10 to the communication slave 20 and for transmission from the communication slave 20 to the communication master 10.

  By the way, in order to avoid interference with other communication systems, it is necessary to avoid frequency channels occupied by other communication systems and perform hopping using available frequency channels. Rather than managing the availability in units of frequency channels, the communication band is divided into several frequency ranges and a table is defined and managed in units of this table. This will be specifically described below.

The communication band used internationally in the 2.4 GHz band ISM band is 2400 MHz to 2483.5 MHz. In the present embodiment, as described above, the communication band is divided into several frequency ranges and the table is defined. When the carrier frequency is provided at 1 MHz intervals, the number of usable frequency channels is 83 channels. As shown in FIGS. 2 and 3, if the table is divided into 8 channels and 10 tables, the frequency range of each table is as follows, and the number of usable frequency channels is 80 channels (10 tables × 8 channels). )
・ Table 0: 2402-2409MHz (all 8 channels)
-Table 1: 2410-2417MHz (all 8 channels)
・ Table 2: 2418-2425MHz (all 8 channels)
-Table 3: 2426 to 2433 MHz (all 8 channels)
Table 4: 2434 to 2441 MHz (all 8 channels)
・ Table 5: 2442 ~ 2449MHz (all 8 channels)
Table 6: 2450-2457 MHz (all 8 channels)
-Table 7: 2458-2465MHz (all 8 channels)
-Table 8: 2466 to 2473 MHz (all 8 channels)
Table 9: 2474-2481MHz (all 8 channels)

  The communication master 10 and the communication slave 20 perform hopping by using all frequency channels of all tables in the initial state, that is, when there is no interference with other communication systems. Specifically, for example, a frequency channel list as shown in FIG. 3 is held in advance by the communication master 10 and the communication slave 20, and the frequency channels indicated in the frequency channel list are alternately hopped in the raster scan order. Send and receive data.

  In FIG. 3, the length of each table is 16 channels, which is twice the above-described 8 channels, but the latter 8 channels are obtained by changing the channel order of the first 8 channels. Specifically, the 8th to 12th channels in each table are the same as the 3rd to 7th channels, and the 13th to 15th channels in each table are the same as the 0th to 2nd channels. It is. In this way, the latter 8 channels are added by changing the channel order of the first 8 channels. This time, the number of available channels is an even number of 80 channels, and hopping is performed with 8 channels in each table. In this case, both the communication master 10 and the communication slave 20 are limited in frequency channels used at the time of transmission (or at the time of reception), and all frequency channels cannot be used.

  In the frequency channel list as shown in FIG. 3, the table order and the in-table channel order are random, and are common only within the same network. In this way, the same communication system can coexist by providing randomness to the hopping order. As a method of sharing a frequency channel list in the same network, for example, an ID is exchanged at the initial device authentication stage between a communication master and a communication slave, and based on the same random number generated based on the ID. To create a frequency channel list. Alternatively, the communication master may create a random frequency channel list and transmit it to the communication slave in advance.

  As described above, the communication master 10 and the communication slave 20 perform data transmission / reception by alternately hopping the frequency channels shown in the frequency channel list as shown in FIG. 3 in the raster scan order. Data may not be received due to interference with the system, and packet errors may occur. In such a case, the communication master 10 obtains a ratio of frequency channels in which a packet error has occurred for each table, and deletes all tables whose ratio exceeds a predetermined threshold at a later-described timing. For example, when table 0 to table 2 become unavailable due to interference with the wireless LAN, as shown in FIG. 3, table 3 → table 0 → table 7 → table 2 → table 1 → table 4 →. In this order, hopping is performed while avoiding an unusable table such as table 3 → table 7 → table 4 →.

  Further, the communication master 10 restores the table once deleted on a trial basis, and adds a table at a later-described timing in order to check whether or not the frequency channel included in the table is available. Unlike the case of table deletion, it is preferable to add a table for each table, but a plurality of tables may be added together. The communication master 10 checks the communication state of the frequency channel included in the added table and the presence / absence of interference in the frequency channel. If the ratio of the frequency channel in which the packet error has occurred is equal to or greater than a predetermined threshold, the table is deleted again. Do.

  Here, the timing for deleting or adding the table is when all the tables that can use the frequency channel go round and return to the top. Therefore, the communication master 10 needs to notify the communication slave 20 of the table used in the next cycle during the previous cycle. Therefore, the communication master 10 adds data mapping a table to be used from a packet more than a predetermined number before the last packet, and notifies the communication slave 20 of table deletion / addition. A data format for transmission and reception is shown in FIG. In FIG. 4, a training signal for data transmission / reception is recorded in the preamble part, data necessary for data transmission / reception is recorded in the header part, and data transmitted / received in an upper layer is recorded in the data part. The data mapping the table to be used is included in the header part together with the address and data length. The table data associates a bit with a table number. For example, “1” is usable, and “0” is unusable. In the case of “1100111001” in FIG. 4, the tables 0, 3, 4, 5, 8, and 9 are usable, and the tables 1, 2, 6, and 7 are unusable.

  The FCC (Federal Communications Commission) stipulates that the number of frequency channels to be hopped is 15 or more, so that the number of frequency channels to be hopped is 15 or more. You must determine the number of tables. In this embodiment, since there are actually only 8 channels per table, at least two tables are used. When the packet error rate exceeds the threshold even with one table while using two tables, the table is not deleted, and an addition confirmation is made as to whether another table can be added immediately. As described above, the addition confirmation is performed when all the tables in which the frequency channel can be used make a round and return to the top. In such a case, the remaining eight tables are added continuously every cycle.

  As described above, according to the communication system 1 according to the present embodiment, whether or not the frequency channel in the ISM band is used is managed in units of tables in which a plurality of frequency channels are collected, not in units of frequency channels. Collision avoidance with a communication system can be performed at high speed, and the consumption of resources such as RAM can be reduced.

  By performing such high-speed processing, it is possible to perform seamless communication even in communication that requires real-time characteristics such as transmission of audio and video. Also, in an environment where a plurality of wireless LANs are constructed on one floor such as an office, the frequency band to be used is often changed depending on the location, but by deleting and adding the table as needed, as described above Even during movement, it is possible to select and use a frequency band according to the environment.

  Also, in an environment where a plurality of networks are constructed with a wireless LAN, a wireless channel to be used can be assumed. Therefore, by setting a table according to the bandwidth of the wireless LAN, the detection speed of the wireless LAN, Detection accuracy can be improved. That is, collision avoidance can be performed at higher speed by setting a table in accordance with the interfering communication system.

  It should be noted that the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the present invention.

  For example, in the above-described embodiment, the table deletion / addition determination criterion is the ratio of frequency channels in which a packet error has occurred. However, the present invention is not limited to this, and the received intensity signal is a predetermined threshold value or less. The ratio of the frequency channel that was a may be used as a criterion.

  Further, in the above-described embodiment, it has been described that information on availability / impossibility of each table is notified to the communication slave. However, the present invention is not limited to this, and only information on available tables is available. Alternatively, only information on tables that cannot be used may be notified to the communication slave.

  Further, in the above-described embodiment, it has been described that information on availability / impossibility of each table is added to the header part. However, the present invention is not limited to this, and notification is made with a control packet or the like. It doesn't matter. In this case, the timing for deleting or adding the table may be synchronized with the control packet.

  In the above description, the timing for deleting or adding a table is set to return to the top after making a round of all the tables that can use the frequency channel, but is not necessarily limited to returning to the top of the table list. The middle of the table list may be used. However, even in this case, it is avoided to notify the change only with the packet immediately before the change, and the data to which the table to be used is mapped is added to the header part from the packet more than a predetermined number before the previous packet.

It is a figure which shows schematic structure of the communication system in this Embodiment. It is a figure which shows the state which divided the communication band in a 2.4 GHz band ISM band into 10 tables for every predetermined frequency range. It is a figure which shows an example of the frequency channel list used for data transmission / reception. It is a figure which shows the format of the data transmitted to a communication slave from a communication master in notifying the table utilized in the next cycle.

Explanation of symbols

1 communication system, 10 communication master, 11 main system, 12 radio unit, 20 communication slave, 21 main system, 22 radio unit

Claims (9)

A communication device that communicates with one or more other communication devices while sequentially changing a plurality of frequency channels,
A communication means for holding a list obtained by dividing the plurality of frequency channels into a plurality of tables for each predetermined number of frequency channels, and transmitting and receiving data while changing the frequency channels in an order according to the list;
A table classification means for detecting a frequency channel that cannot be used for communication from the plurality of frequency channels, and classifying a table in which a ratio of frequency channels that cannot be used for communication exceeds a predetermined threshold as an unusable table;
The communication means notifies the other communication device of information on the usable table and / or the unusable table, and changes the frequency channel included in the usable table in the order according to the list. A communication device characterized by transmitting and receiving.   2. The communication apparatus according to claim 1, wherein the table classifying unit periodically classifies one or more tables among the tables classified as unusable as usable tables.   The communication means, when making a round of frequency channels included in an available table, notifies the other communication apparatus of information on an available table and / or an unavailable table. The communication apparatus according to 1. A communication method for communicating with one or more other communication devices while sequentially changing a plurality of frequency channels,
A communication step of holding a list obtained by dividing the plurality of frequency channels into a plurality of tables for each predetermined number of frequency channels, and transmitting and receiving data while changing the frequency channels in an order according to the list;
A table classification step of detecting a frequency channel that cannot be used for communication from the plurality of frequency channels, and classifying a table in which a ratio of frequency channels that cannot be used for communication exceeds a predetermined threshold as an unusable table;
In the communication step, information on available tables and / or unavailable tables is notified to the other communication devices, and data is changed while changing frequency channels included in the usable tables in the order according to the list. A communication method characterized by transmitting and receiving.   5. The communication method according to claim 4, wherein in the table classification step, one or more tables among the tables classified as unusable are periodically classified as usable tables.   The communication step is characterized in that, when making a round of frequency channels included in an available table, information on an available table and / or an unavailable table is notified to the other communication device. 4. The communication method according to 4. A list obtained by dividing a plurality of frequency channels into a plurality of tables for each predetermined number of consecutive frequency channels is held, and the frequency channel is changed in an order according to the list, and the first communication device and one or more second channels A communication system for transmitting and receiving data to and from the communication device,
The first communication device detects a frequency channel that cannot be used for communication from the plurality of frequency channels, and classifies a table in which a ratio of frequency channels that cannot be used for communication exceeds a predetermined threshold as an unusable table. To inform the one or more second communication devices of information on available tables and / or unavailable tables,
The communication system, wherein the first communication device and the one or more second communication devices transmit and receive data while changing frequency channels included in an available table in an order according to the list.   8. The communication system according to claim 7, wherein the first communication device periodically classifies one or more tables among the tables classified as unusable as usable tables. When the first communication device makes a round of the frequency channels included in the available table, the first communication device notifies the information of the available table and / or the unavailable table to the one or more second communication devices. The communication system according to claim 7.

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