JP2009260792A - Channel selection circuit and selection method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To efficiently ensure an idle channel in a communication unit performing channel selection, thereby shortening a time before starting communication. <P>SOLUTION: In a channel selection circuit of the communication unit, starting communication by selecting a communication channel after confirming an idle channel state while sequentially scanning channels, based on the measured data of radio field intensity received from an antenna, preset preferential channel information is stored in a data recording unit connected to a channel control circuit. Based on the preferential channel information, an RF circuit sets a preferential channel, and measures the radio field intensity. An RSSI storage circuit stores the measured data of received data. A decision circuit compares the measured data with a preset threshold. If the measured data is lower than and inclusive of the threshold, it is decided to be an idle channel, while if the measured data exceed the threshold, it is decided to be a channel in use for another unit. In the decision results by the decision circuit, when the idle channel is indicated, the channel control circuit instructs to start communication, while when the channel in use is indicated, the channel control circuit instructs to set next selection channel. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a communication apparatus that performs communication channel selection, and particularly to a channel selection circuit and a selection method thereof that enable efficient channel selection.

  In recent years, LSI (Large Scale Integration) products of the IEEE 802.15.4 2.4 GHz short-range wireless standard have been used in communication devices such as TV remote controllers. In IEEE802.15.4, 16 channels are assigned as ch11 to ch26 with a bandwidth of 2 MHz every 5 MHz in a band from 2.4 GHz to about 2.484 MHz. However, in this 2.4 GHz frequency band, there are products that transmit radio waves of various standards such as wireless LAN (Local Area Network), Bluetooth, microwave ovens, etc. that are used nearby, for efficient communication In addition, the communication apparatus is required to select an optimum channel while avoiding interference with these radio waves.

  In particular, the IEEE802.15.4 standard is characterized by low power consumption assuming battery operation. For example, in the case of a TV remote control, it is possible to quickly find an empty channel and increase the response speed, thereby saving power. Propulsion and long-time driving are required.

  Conventionally, in this channel selection, scanning is sequentially performed from the lowest channel (ch11) or the highest channel (ch26), and the status of all channels is measured to secure an empty channel.

By the way, Patent Literature 1 discloses a wireless communication apparatus that performs channel selection in order of priority based on estimation of an interference wave interference source, and Patent Literature 2 performs channel selection in consideration of past use frequency. A wireless communication device is disclosed.
JP 2005-198028 Japanese Patent Laid-Open No. 11-341554

  In the conventional channel selection circuit and its selection method, scanning is executed in order from the lowest or highest channel. In particular, as shown in FIG. 5, when scanning is performed from the lowest position in an environment shared with a wireless LAN, the lower four channels (ch11 to ch14) are channels (Ch. Despite the possibility of being unable to secure a free channel because it overlaps with 1), it wasted time to scan and check the free status.

  The present invention eliminates such drawbacks of the prior art, efficiently secures a free channel, and can shorten the time required to start communication, that is, the system start-up time, thereby realizing low power consumption. An object is to provide a channel selection circuit and a selection method thereof.

  According to the present invention, in order to solve the above-mentioned problems, communication is performed by checking channel vacancy based on radio field intensity measurement data received from an antenna while sequentially scanning channels, and selecting a communication channel. The channel selection circuit of the communication device for performing the priority channel information storage means for storing the preset priority channel information in the data recording unit connected to the channel control circuit, and the determination circuit and the channel control circuit connected to the channel control circuit. When the actual channel information storage means for storing actual channel information with past usage records in the data recording unit 2 and when the actual channel information usage count is greater than or equal to the preset number, the actual channel information is less than Is selected channel information selection means using the priority channel information as the selected channel information, and based on the selected channel information. Measures the received data quantitatively by setting the selected channel in the radio frequency (RF) circuit and measures the radio field intensity, and stores the received data measurement data in the received signal strength indicator (RSSI) storage circuit The measurement data storage means to compare the measurement data with the threshold set in advance by the determination circuit. When the measurement data is below the threshold, the channel is determined to be an empty channel, and when the threshold is exceeded, the channel is determined to be a channel in use by another device. An idle state determining means, and a channel scanning means in the channel control circuit for instructing the start of communication when the determination result of the determining circuit is an empty channel, and for setting the next priority channel when the channel is in use. It is characterized by including.

  In addition, a method for performing channel selection for a communication device that performs communication by selecting a communication channel and checking a channel free state based on radio wave intensity measurement data received from an antenna while sequentially scanning the channel. A prioritized channel information storing step for storing preset priority channel information in a data recording unit connected to the control circuit, and a past data record in the second data recording unit connected to the determination circuit and the channel control circuit. The actual channel information storage step for storing actual channel information, and when the actual channel information usage count is equal to or greater than the preset number, the actual channel information is selected, and when the actual channel information is less, the priority channel information is selected channel information. Based on the selected channel information selection process and the selected channel information, the selected channel is set by the RF circuit. When the received data quantitative measurement process for measuring the radio field strength, the measured data storage process for storing the received data measurement data in the RSSI storage circuit, and the threshold value set in advance by the judgment circuit are compared with the preset threshold value. Determines whether the channel is an empty channel, and when the threshold is exceeded, determines whether the channel is in use by another device. If the channel control circuit determines that the result of the determination by the determination circuit is an empty channel, communication is performed. And a channel scan step of instructing the setting of the next priority channel when the channel is in use.

  Next, an embodiment of the channel selection circuit 100 according to the present invention will be described in detail with reference to the accompanying drawings. For example, the channel selection circuit 100 of this embodiment includes a control circuit 12, an LSI 14 electrically connected to the control circuit 12, and an antenna 16 electrically connected to the LSI 14 as shown in FIG. Consists of including. Note that portions not directly related to understanding the present invention are not shown and redundant description is avoided.

  The control circuit 12 is connected to the channel control circuit 18 of the LSI 14 and issues a command, exchanges channel information, and performs system control such as channel selection.

  The LSI 14 includes a channel control circuit 18, a first RAM (Random Access Memory) 20, an RF circuit 22, an RSSI storage circuit 24, and a determination circuit 26.

  The antenna 16 is connected to the RF circuit 22 of the LSI 14 and transmits and receives radio waves.

  The channel control circuit 18 of the LSI 14 obtains the priority channel information from the first RAM 20 and the channel determination result information from the determination circuit 26 on the basis of the command signals 112 and 116 from the connected control circuit 12 to obtain the channel. Make a selection. The channel control circuit 18 is connected to the RF circuit 22 and notifies the RF circuit 22 of the channel selection result 120.

  The first RAM 20 temporarily stores priority channel information sent from the control circuit 12 via the channel control circuit 18.

  The RF circuit 22 receives the signal sent from the channel control circuit 18, sets the channel, receives the radio wave condition of the set channel with the antenna 16, and quantitatively measures the radio wave intensity of the received radio wave. 122 is transmitted to the RSSI storage circuit 24.

  The RSSI storage circuit 24 is connected to the RF circuit 22 and the determination circuit 26, temporarily stores the RSSI value 122 sent from the RF circuit 22, and provides it to the determination circuit 26.

  The determination circuit 26 is connected to the RSSI storage circuit 24 and the channel control circuit 18, and if the 124 value stored in the RSSI storage circuit 24 is greater than or equal to a threshold value, it is a busy channel, and if it is less than the threshold value, it is empty. The channel is determined to be a channel and the result is notified to the channel control circuit 18.

  Next, the channel selection operation in the channel selection circuit 100 of the present embodiment will be described with reference to the operation flow diagram of FIG.

  Priority channel setting that is set in advance so that when a communication start command from outside such as key operation is performed, a channel that does not overlap with a channel often used in other wireless systems such as a wireless LAN used nearby is given priority The command 112 is issued from the control circuit 12 (S202), and the priority channel information 114 is temporarily stored in the first RAM 20 via the channel control circuit 18 of the LSI 14 (S204).

  Subsequently, the channel scan setting command 116 is issued from the control circuit 12 to the channel control circuit 18 (S206), and the channel control circuit 18 reads the priority channel information 118 from the first RAM 20 (S208), and the priority channel, for example, the channel 1 is determined (S210), and the determined channel information 120 is sent to the RF circuit 22.

  The RF circuit 22 sets channel 1 from the decision channel information 120 sent from the channel control circuit 18, receives the data of the set channel at the antenna 16 (S212), and quantitatively measures the radio field intensity. (S214).

  The measurement result is stored in the RSSI storage circuit 24 as the RSSI value 122 (S216).

  If the RSSI value 124 called from the RSSI storage circuit 24 in the determination circuit 26 is equal to or greater than a predetermined threshold value, the channel 1 is determined to be an in-use channel, and if it is less than the threshold value, it is determined to be an empty channel (S218). ).

  If it is determined that the channel is an empty channel, the determination result 126 is notified to the control circuit 12 via the channel control circuit 18 (S222), and data communication is started on that channel.

  If it is determined that the channel is in use, the channel control circuit 18 determines the next priority channel stored in the first RAM 20, for example, channel 2 (S 220) and sends it to the RF circuit 22.

  Thereafter, in the same manner, the channel scan is repeatedly executed in order from the priority channel until an empty channel is found.

  Here, the threshold value for determining the used channel and the free channel can be arbitrarily set in consideration of the radio wave environment such as the status of other products performing wireless communication in the vicinity.

  Next, another embodiment of the channel selection circuit according to the present invention, that is, the configuration of the second embodiment will be described in detail with reference to FIG. The same components as those in the first embodiment are denoted by the same reference numerals, and repeated description is avoided as much as possible.

  The second channel selection circuit 200 detects a vacant channel in a shorter time using the past used channel results, and includes a control circuit 12, an LSI 34 electrically connected to the control circuit 12, And an antenna 16 electrically connected to the LSI.

  The LSI 34 includes a channel control circuit 38, a first RAM 20, an RF circuit 22, an RSSI storage circuit 24, a determination circuit 46, and a second RAM 48.

  The determination circuit 46 is connected to the second RAM 48, and when the channel is determined by the same operation as in the first embodiment, when it is determined that the channel is an empty channel, the information is sent to the second RAM 48. To do.

  The second RAM 48 is connected to the determination circuit 46 and the channel control circuit 38, and is used in the determination circuit 46 in order to provide information on past free channel results when the channel control circuit 38 performs channel selection. The information when it is determined as a channel is accumulated and stored.

  Next, the operation of the second embodiment will be described with reference to the operation flowchart of FIG. Since the operation other than the newly added operation is the same as that of the first embodiment, the description will be simplified and detailed repetitive description will be avoided.

  First, when a communication start command is issued in the same manner as in the first embodiment, a preset priority channel setting command 112 is issued from the control circuit 12 (S302), and passes through the channel control circuit 38 of the LSI 34 to the first RAM. The priority channel information 114 is temporarily stored in 20 (S304).

  Subsequently, a channel scan setting command 116 is issued from the control circuit 12 to the channel control circuit 38 (S306), and the channel control circuit 38 reads the priority channel information 118 from the first RAM 20 (S308), and the second RAM 48 The past used channel information 130 is read from (S310).

  The channel control circuit 38 makes a determination based on the past use channel information based on the past use channel information (S312), and the use track number is determined as a track record channel, for example, channel 1 at least, for example, five times or more. The result is sent to the RF circuit 22 as decision channel information 120 (S314). If there is no actual usage channel more than the desired number of times, the priority channel is determined from the priority channel information from the first RAM 20 as in the first embodiment (S316), and the determined channel information 120 is sent to the RF circuit 22 as the determined channel information 120. Sent.

  Thereafter, as in the first embodiment, the determined channel receives data of the channel set by the antenna 16 (S318), the RSSI value 122 is stored in the RSSI storage circuit 24 (S322), and the RSSI is stored. The radio field intensity is quantitatively measured from the RSSI value 124 called from the circuit 24 (S320), and the determination circuit 46 determines whether the channel is an empty channel or a busy channel with a certain predetermined threshold (S324). ).

  When it is determined that the channel is an empty channel, the determination result 126 is stored as the actual channel information 128 in the second RAM 48 and is notified to the control circuit 32 via the channel control circuit 38 (S328). Communication is started.

  If it is determined that the channel is in use, the channel control circuit 38 reads the next priority channel stored in the first RAM 20 and the next past used channel information stored in the second RAM 48 ( S326), the determination is performed in the same manner as in the first time, for example, channel 2 is determined and sent to the RF circuit 22.

  The channel vacancy state is quantitatively measured, and the actual channel scan or the priority channel scan is repeatedly executed until a vacant channel is found.

  Although the embodiments of the present invention have been described above, according to the first embodiment, priorities are set by avoiding channels that are likely to overlap with channels used by wireless systems such as wireless LANs. Thus, it is possible to detect the open channel efficiently.

  For example, as shown in FIG. 5, when trying to detect an empty channel in an environment where Ch.1, Ch.6, and Ch.11, which are frequently used in a wireless LAN, are used, ch11 to ch14 of IEEE802.15.4 Despite overlapping with wireless LAN Ch.1, check the available channels sequentially from ch11. For this reason, it takes time to confirm ch.15, which has a high possibility of an empty channel.However, as shown in this example, information on channels that do not overlap such as ch.15, ch.20, and ch.25 is set in advance. This increases the probability that an empty channel can be detected quickly. If an empty channel is detected on priority channel 1 (ch.15), it can be detected in about 1/5 of the time required to search for an empty channel while performing conventional sequential scanning (Fig. 6). Data communication can be started early.

  Further, according to the second embodiment, in addition to the first embodiment that can efficiently detect an empty channel, detection is performed from individual past information channels that have a high possibility of an empty channel. An empty channel can be detected in a shorter time than this.

  In this embodiment, an example in which a RAM is used as a storage element for channel information such as a priority channel and a performance channel has been described. For example, other data storage means such as a logic circuit using Flip Flop is used. It doesn't matter.

  As described above, according to the present invention, when using a communication device using the IEEE802.15.4 standard, an optimum channel can be selected efficiently and in a short time by avoiding interference with radio waves used by other devices. Therefore, it is possible to ensure a long power saving period, and it is possible to achieve low power consumption as a system.

  In this embodiment, an example using the IEEE802.15.4 standard as a communication system has been described. Needless to say, any communication system that requires channel selection can be applied.

It is a block diagram which shows the structural example of the channel selection circuit by the Example of this invention. 2 is a flowchart showing the operation of the channel selection circuit shown in FIG. It is a block diagram which shows the structural example of the channel selection circuit by the other Example of this invention. 4 is a flowchart showing an operation of the channel selection circuit shown in FIG. 3. It is a figure which shows the use channel of the channel selection circuit by the Example of this invention. It is a figure which shows the channel selection operation | movement of the channel selection circuit by the Example of this invention.

Explanation of symbols

100, 200 channel selection circuit
12, 32 Control circuit
14, 34 LSI
16 Antenna
18, 38 channel control circuit
20 1st RAM
22 RF circuit
24 RSSI storage circuit
26, 46 Judgment circuit
48 2nd RAM

Claims (4)

In the channel selection circuit of the communication apparatus that checks the vacant state of the channel based on the measurement data of the radio field intensity received from the antenna while sequentially scanning the channel, selects the communication channel, and starts communication.
Priority channel information storage means for storing preset priority channel information in a data recording unit connected to the channel control circuit;
Based on the priority channel information, the received data quantitative measurement means for setting the selected channel in the high frequency circuit and measuring the radio field intensity,
Measurement data storage means for storing measurement data of the reception data in a reception signal strength indicator storage circuit;
The determination circuit compares the measurement data with a preset threshold value, determines that the channel is an empty channel when the threshold value is lower than the threshold value, and determines whether the channel is available when other channels are used.
A channel control circuit including channel scan means for instructing communication start when the determination result of the determination circuit is an empty channel, and for setting the next selected channel when the channel is in use. Selection circuit. The channel selection circuit according to claim 1, wherein
Actual channel information storage means for storing actual channel information with past usage records in the second data recording unit connected to the determination circuit and the channel control circuit;
A channel comprising: selection channel information selection means for selecting the actual channel information when the actual channel information usage count is equal to or greater than a preset count, and when the actual channel information is less than the preset channel information; Selection circuit. In the channel selection method of the communication device that checks the vacant state of the channel based on the measurement data of the radio field intensity received from the antenna while sequentially scanning the channel and starts communication by selecting the communication channel, the method includes:
A priority channel information storage step for storing preset priority channel information in a data recording unit connected to the channel control circuit;
Based on the priority channel information, a quantitative measurement process of received data for setting a selected channel in a high-frequency circuit and measuring radio field intensity;
A measurement data storage step of storing measurement data of the reception data in a reception signal strength indicator storage circuit;
The determination circuit compares the measurement data with a preset threshold value, and when it is equal to or less than the threshold value, it is determined as an empty channel, and when the threshold value is exceeded, a channel empty state determination step for determining as an in-use channel of another device;
A channel control circuit, comprising: a channel scan step of instructing communication start when the determination result of the determination circuit is an empty channel, and instructing setting of the next priority channel when the channel is in use Selection method. The channel selection method according to claim 3,
An actual channel information storing step of storing actual channel information with past usage records in the second data recording unit connected to the determination circuit and the channel control circuit;
A channel including a selection channel information selection step in which the actual channel information is used when the actual channel usage count is equal to or greater than a preset count, and when the actual channel information is less than the preset channel information. Selection method.

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