JP2008035174A - Radio communication apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radio communication apparatus which controls a processing cost, selects an optimum frequency channel by communication partner by adding a request of an application to a surrounding radio wave environment, and improves a data transfer efficiency of an entire network. <P>SOLUTION: A channel communication quality evaluator 13 evaluates a communication quality of each frequency channel by using a receiving electric field strength, an error detection frequency, an error correction frequency or a packet re-sending state and the like, every time when a transmission and a receiving are executed; and holds a table of an evaluation result by communication partner, by use packet or by communication content. A channel quality placing processor 14 conducts a placing of the frequency channel on the basis of these evaluation results. A transmitting and receiving operation managing portion 2 selects, and controls the optimum frequency channel based on the places. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a wireless communication apparatus that performs communication while switching a plurality of frequency channels when performing wireless transmission in a time division manner.

  In general, a wireless communication method called a frequency hopping method, which is one of spread spectrum methods that is resistant to noise, has high fault tolerance, and has excellent communication confidentiality, is known.

  In wireless communication using the frequency hopping method, a communication frequency band is divided into a plurality of fine frequency channels, and each frequency is used for communication in a time division manner, thereby realizing frequency spreading and increasing error resistance. In this communication technology using frequency hopping, the communication state is averaged by uniformly spreading the frequency used, and as a whole, it is difficult to make an extreme difference in the communication state, and the connection is maintained even in an environment where the communication state is bad. Things are possible.

  Currently, there is a communication standard called Bluetooth (registered trademark) that performs wireless communication by this frequency hopping method. The frequency band of 2.45 GHz used by this communication standard is used not only for Bluetooth but also for other wireless communication systems such as a wireless LAN standardized by IEEE 802.11b. Communication speed and quality may be degraded.

For this reason, based on the error rate of packets in each frequency channel and the evaluation of the received signal field strength, frequency channels that do not meet the standards are not used within a range that does not fall below the minimum required number of channels, resulting in quality degradation due to interference. Has been disclosed (for example, see Patent Document 1).
JP 2005-244330 A

  However, the frequency channel selection method as disclosed in Patent Document 1 has the following problems.

  First, when there are multiple communication partners, even if the same frequency channel is used, there is a difference in evaluation results such as received electric field strength due to the difference in distance from the connection partner. In order to evaluate the channel quality without taking into account the state of the other party, if there is even one connection partner whose communication quality is significantly different, there is a problem that it is not appropriate to determine whether to use or not use the frequency channel.

  Second, when changing the threshold value in order to secure the required number of channels, if the change width of the threshold value is increased, a frequency channel with poor communication quality may be used. There is a problem that it cannot be performed, or if an optimum frequency channel selection is performed by reducing the change width of the threshold value, there is a problem that many reselections must be performed before the necessary number of frequency channels is secured.

  On the other hand, if the communication quality of the frequency channels is ranked, this problem is eliminated. However, according to Patent Document 1, it is pointed out that the ranking by a general sorting algorithm is expensive.

  The object of the present invention is to reduce the processing cost, and to select the most suitable frequency channel for each communication partner in consideration of the application request in the surrounding radio wave environment, and to improve the data transfer efficiency of the entire network. A wireless communication device is provided.

  In view of such circumstances, the wireless communication device according to the first invention is a communication device for performing wireless communication using a plurality of frequency channels, and performs error detection or correction of received data and analysis of received data. A data analysis unit, a channel communication quality evaluation unit that evaluates communication quality of a frequency channel received from the analysis result of the data analysis unit, and an evaluation value output from the channel communication quality evaluation unit, and ranking of frequency channels A channel quality ranking processing unit for performing transmission and a control unit for performing control for selecting a frequency channel for transmission and reception with reference to data of the channel quality ranking processing unit.

  Further, in the wireless communication apparatus according to the second invention, each time the channel quality ranking processing unit holds data of an array for ranking frequency channels, and an evaluation value is output from the channel communication quality evaluating unit. It is characterized by searching for a place to insert the evaluation value and updating the array data.

  In the wireless communication device according to the third invention, the channel quality ranking processing unit determines whether the sequence data is classified by packet type such as communication partner, error correction capability, presence / absence of retransmission control, or control information. A plurality of data types are stored for each data type, and when the frequency channel is selected, the control unit determines the communication partner, the packet type or the data type, selects one of the array data, and controls the frequency channel. It is characterized by.

  The wireless communication apparatus according to a fourth aspect is characterized in that the channel communication quality evaluation unit outputs an evaluation value based on a plurality of indices.

  The wireless communication apparatus according to a fifth aspect of the invention is characterized in that the channel communication quality evaluation unit weights evaluation values for each of the indices, and adds up all evaluation values to calculate a frequency channel evaluation value. To do.

  In the wireless communication device according to the sixth invention, the index is a received electric field strength, a frequency of error correction or detection of data, a bit error rate or a packet retransmission rate in a fixed pattern portion in transmission / reception data, etc. And

  The radio communication apparatus according to a seventh aspect is characterized in that the control unit selects a frequency channel and selects data to be transmitted based on the order of the frequency channel.

  According to an eighth aspect of the present invention, there is provided a wireless communication apparatus comprising a table for synchronous transfer, wherein the control unit selects one of the ranked array data with reference to the table.

  According to the present invention, it is possible to select an optimum frequency channel for each communication partner, each used packet, and each communication content in consideration of the application request in the surrounding radio wave environment. It is possible to improve.

  In addition, since an array in which ordering is arranged at any time is used, it is only necessary to search for an insertion position in the array at the time of updating, the alignment process is simplified, and the processing cost can be reduced.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram of a wireless communication device 1 according to an embodiment of the present invention.

  The transmission / reception operation management unit 2 basically performs transmission / reception timing management, link management, and data retransmission control management in accordance with the communication standard.

  When transmission data is generated by the transmission data generation unit 3 as a data transmission operation, the transmission packet selection unit 4 transmits a transmission packet based on transmission timing control, link control, and data retransmission control information from the transmission / reception operation management unit 2. The transmission packet construction unit 5 obtains outputs from the transmission data generation unit 3 and the transmission packet selection unit 4 and constructs the transmission packet according to the communication standard. Further, based on the control information from the transmission / reception operation management unit 2, the channel selection unit 6 selects a transmission channel, the transmission / reception frequency control unit 7 controls the transmission frequency, and the transmission packet construction unit 5 and the transmission / reception frequency control unit 7. , Is modulated by the transmission circuit 8, and a transmission signal is output from the antenna 9.

  As a data reception operation, a channel selection unit 6 selects a reception channel based on information on reception timing control, link control, and data retransmission control from the transmission / reception operation management unit 2, and based on information from the channel selection unit 6 The transmission / reception frequency control unit 7 performs reception frequency control, obtains control information output from the transmission / reception frequency control unit 7, performs data demodulation in the reception circuit 10, and receives data error detection / correction in the reception data analysis unit 11. The received data is obtained by analyzing the received packet and outputting it to the received data processing unit 12.

  In transmission and reception channel selection, selection is performed according to the frequency hopping pattern defined in the standard. Which channel is used in this pattern is determined by the standard in link management. It is determined on both the transmission side and the reception side using.

  In the present invention, in addition to the above processing, during the reception operation, the channel communication quality evaluation unit 13 evaluates the communication quality of the channel performing the reception operation based on the result of the reception data analysis unit 11, and the channel Each time the quality ranking processing unit 14 completes the receiving operation, the channel quality ranking is also performed. This order information is output to the transmission / reception operation management unit 2 and is used as control information for selecting a channel by the channel selection unit 6.

  By the way, as pointed out in Patent Document 1, if a general sorting algorithm for ranking is implemented, the processing cost is high. This is because a general algorithm is based on the premise that the original ranking is basically not aligned, and is intended to perform a complete sorting. However, in the present invention, the ordering process is simplified by performing the ranking every time the reception operation is completed, so that the problem of the processing cost can be solved.

  First, the evaluation of communication quality is ultimately expressed as a numerical value regardless of the evaluation method, and there are no particular restrictions on the numerical expression format. For example, it is arbitrarily set in consideration of the cost of the system and the ease of mounting, such as 256 steps by integers from 0 to 255, two decimal steps from 0.0 to 1.0, or 0 or 1. The ranking is not the same ranking even when the evaluation results are exactly the same, and a ranking difference is always given. In this case, there is no particular restriction on the method of selecting which channel is the higher rank. Based on this rule, the channel quality ranking processing unit 14 has a table indicating the relationship between the ranking, the channel number, and the communication quality evaluation value.

[Rating communication quality]
Next, a communication quality ranking procedure when receiving will be described.

  In starting the communication system according to the present invention, the channel quality ranking processing unit 14 initializes the table. In this initialization, the relationship between the quality evaluation value and the ranking of each channel is made consistent as an aligned state. For example, even if the ranking is arbitrary, there is no problem because it can be considered that there is no contradiction in the rules and that the evaluation values are aligned if the evaluation values are all the same value.

  The above initialization is performed, and various processes for the reception operation are started. Each time reception is completed, the communication quality of one channel is evaluated. As a result of the evaluation, the channel is newly re-ordered, but the order of other channels is originally stored and aligned in the array, so there is no need to rearrange, and the order should be inserted. May be processed in order from the upper or lower order. Alternatively, it is possible to easily determine by dividing the array into two parts, the upper part and the lower part, and searching for which one is included, or searching using a tree structure such as a binary tree.

  In this way, the channel ranking arrangement is always kept in order, so when reducing the number of channels, simply select the channel from the top in consideration of the minimum number of channels. Processing becomes easy.

  The number of tables used for ranking in this method may be one for the entire system, but if there are a plurality of tables by communication partner, by packet type, by data content, or a combination thereof, Therefore, it can be used for finer channel allocation.

  Here, according to the type of packet used, for example, in the Bluetooth standard, the packet type is distinguished by the error correction capability and the presence / absence of retransmission control. That is, based on this classification, it is possible to allocate a channel of good quality in a link that uses a packet with low error correction capability or not defined for retransmission control.

  The data contents are classified according to, for example, link control information or other data. That is, based on this division, it is possible to allocate a channel of good quality to the link control information. However, in the way of dividing the data contents, the table may be prepared in more detail in consideration of the conditions such as whether high-speed transfer or isochronism is required for higher-level link identification. When preparing a table in detail, for example, in the Bluetooth standard, it is possible to inform each other using a procedure defined in the specification for a table by communication partner. The link identification number needs to be associated with the table. For example, a mode in which a dedicated table is used for synchronization or isochronous data may be prepared, or a link identification number may be sent at the same time when the table is sent.

[Evaluation of communication quality]
Next, examples of indexes for evaluating communication quality are given.

  First, the received electric field strength is given as an index. If it is actually used for communication, it is desirable that it is within a certain range in light of the specifications of the receiving circuit. Conversely, if the channel is not used for communication, the strength is below a certain level. It is desirable that Therefore, it is necessary to determine the evaluation value according to the channel usage state of the device itself. If this index is used for the communication partner ranking table, it is more effective because it is in line with the current situation.

  Next, it is conceivable to use, as an index, the ratio of correction or detection performed in the error correction or error detection function performed in the reception data analysis unit 11. For example, in the Bluetooth standard, in a portion to which error correction by 1/3 FEC (Forward Error Correction, forward error correction control method) is applied, the number of received bits and the number of corrected bits are monitored for a certain period to obtain a ratio. Things are possible. In the bit error check of the packet header part, it is possible to obtain the ratio between the number of received packets and the number of detected errors. In addition, the error correction / detection result by 2/3 FEC and the error check result of the data part by CRC (Cyclic Redundancy Check) can be used in the same manner. Both of these are evaluations for the channel being used.

  In addition, quality evaluation using a synchronization word is also possible. In this case, when the synchronization word can be detected, the error rate can be obtained by counting the number of error bits included in the synchronization word. In addition, even when the synchronization word cannot be detected even though there should have been transmission from the other party in the communication standard, it is possible to count because the error is greater than the allowable number of errors.

  Also, quality evaluation based on the packet retransmission rate is possible. This can be both reception and transmission. First, in the case of reception, the number of times of requesting retransmission is counted with respect to the number of times of reception of a packet that may request retransmission. In the case of transmission, the number of retransmissions is counted with respect to the number of transmissions of packets that may be retransmitted. Here, at the time of retransmission, it is unclear which channel was previously transmitted at the time of retransmission, so it is necessary to record so that the previous transmission channel can be known.

  By using the methods described so far, one or more evaluations are obtained for each channel of one or more tables.

  When ranking is performed with only one index, the value of the evaluation result may be used as it is. However, when a plurality of indices are taken into consideration, a weighting coefficient for each index is set in advance. Then, after normalizing the results of each index within a common range such as 0.0 to 1.0 or 0 to 255, the numerical values of these evaluation results are multiplied by a weighting coefficient, and these numerical values are added up. Or, when multiplied, it can be used as a ranking that takes into account the importance of the index.

  2A to 2C are examples of tables stored in the channel communication quality evaluation unit 13. FIG. 2A is a weighting coefficient table. FIG. 2B is a table of evaluation results for each channel for each index. FIG. 2C shows a table of evaluation values multiplied by weighting coefficients and added together. The channel B showed evaluation results with higher values than the channel A for the indicators D and E. However, when the weighting is performed, the channel A has a higher value for the indicator F having a higher weighting coefficient, so the final evaluation is performed. The value is higher for channel A, and FIG. 2D is an example of a ranking table stored in the channel quality ranking processing unit 14, but the ranking of channel A is higher than the ranking of channel B. Become. In this way, an evaluation value that takes into account the importance of the index is calculated for a plurality of indices.

  For example, even if the electric field strength is not weak as a result of the evaluation based on the received electric field strength, if it is too close and too strong, or if there is interference with other signals, the quality of the evaluation by error correction / detection etc. The result is not good. In such a case, weighting is applied to the result of the received electric field strength and the result of error correction / detection, and these values are multiplied or added to enable effective ranking to improve the actual transfer rate. Become.

  As another method, weighting is performed by changing the normalization range for each index, and these numerical values are added or multiplied. The result is equivalent only by changing the order of calculation.

  Also, for example, the error correction / detection capability for bit errors may be different for each part of the packet, such as 1/3 FEC or 2/3 FEC, and it may be possible to use both pieces of information for the entire reception operation. is there. In such a case, since the evaluation axes are of the same type in terms of bit error tolerance, a method of determining weights and adding or multiplying them may be used.

  With the method described above, the communication quality of each channel is evaluated and ranked in accordance with one or more tables.

The selection of the channel actually used for transmission / reception starts by selecting which table to use when using a plurality of tables.
For example, since it is not possible to limit the channels used for each other at the start of communication, all channels are used. If all channels can be used and a link is established, and there is a table for each communication partner, assign which channel to use for each communication partner, and the table will be displayed each time the communication partner is switched. It will be switched.

  In synchronous transfer in the Bluetooth standard or the like, communication is performed in a state in which the time for transferring synchronous data is determined. In such a case, for example, a table for synchronous transfer may be held in a storage unit (not shown), and based on the table for synchronous transfer, it may be determined whether it is time for synchronous transfer and the table may be switched.

  Even when only one table is provided, after selecting a channel, the packet or data to be transmitted may be changed depending on the communication quality of the channel.

  For example, if the selected channel is higher in the ranking, packets that are susceptible to communication quality such as low error correction capability, no retransmission capability, long data length, or needing isochronism It may be possible to preferentially select and send important packets of content. Further, when the quality of the selected channel is not so good and the ranking is low, a packet of a link with a low communication frequency or a low communication speed may be transmitted.

  As described above, the present invention makes it possible to select an optimal frequency channel for each communication partner, each used packet, and each communication content in consideration of an application request in the surrounding radio wave environment, and data transfer of the entire network It is possible to improve efficiency.

  In addition, since an array in which ranking is arranged at any time is used, processing for searching for an insertion position in the array may be performed at the time of update, and the processing cost can be reduced.

  Note that the wireless communication apparatus of the present invention is not limited to the above-described illustrated examples, and various modifications can be made without departing from the scope of the present invention.

It is a block diagram of the radio | wireless communication apparatus in embodiment of this invention. (A) is a table of weighting coefficients, (b) is an evaluation result of each channel, (c) is a table of evaluation values obtained by weighting the evaluation results of each channel, and (d) is a ranking table. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Wireless communication apparatus 2 Transmission / reception operation management part 3 Transmission data generation part 4 Transmission packet selection part 5 Transmission packet construction part 6 Channel selection part 7 Transmission / reception frequency control part 8 Transmission circuit 9 Antenna 10 Reception circuit 11 Reception data analysis part 12 Reception data processing Unit 13 channel communication quality evaluation unit 14 channel quality ranking processing unit

Claims (8)

A communication device for performing wireless communication using a plurality of frequency channels,
A data analysis unit that performs error detection or correction of received data and analyzes received data;
A channel communication quality evaluation unit for evaluating the communication quality of the frequency channel received from the analysis result of the data analysis unit;
A channel quality ranking processing unit that ranks frequency channels from the evaluation value output from the channel communication quality evaluation unit;
A wireless communication apparatus comprising: a control unit that performs control for selecting a frequency channel for transmission and reception with reference to data of the channel quality ranking processing unit.   The channel quality ranking processing unit holds data of an array for ranking frequency channels, searches for a place where the evaluation value is inserted each time an evaluation value is output from the channel communication quality evaluation unit, The wireless communication apparatus according to claim 1, wherein data is updated.   The channel quality ranking processing unit holds a plurality of the array data for each communication partner, for each packet type such as error correction capability or presence / absence of retransmission control, or for each data type such as control information, and so on. The wireless communication according to claim 2, wherein when selecting a frequency channel, a communication partner, a packet type or a data type is determined and one of the array data is selected to control a frequency channel. apparatus.   The wireless communication apparatus according to claim 1, wherein the channel communication quality evaluation unit outputs an evaluation value based on a plurality of indices.   The radio communication apparatus according to claim 4, wherein the channel communication quality evaluation unit weights an evaluation value for each index, and calculates an evaluation value of a frequency channel by adding all the evaluation values.   6. The index according to claim 4, wherein the index is a received electric field strength, a frequency of error correction or detection of data, a bit error rate or a packet retransmission rate in a fixed pattern portion in transmission / reception data, or the like. Wireless communication device.   The wireless communication according to any one of claims 1 to 6, wherein the control unit selects a frequency channel and selects data to be transmitted based on the order of the frequency channel. apparatus.   7. The system according to claim 3, further comprising a table for synchronous transfer, wherein the control unit selects one of the ranked array data with reference to the table. The wireless communication device described.

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