JP2005033418A - Frequency hopping communication device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a frequency hopping communication device for maintaining communication quality by coping with even a change in a wireless environment in communication for a long time. <P>SOLUTION: The frequency hopping communication device having a standby frequency carrier list, is characterized in to include: an electric field strength measurement means that receives standby frequency carriers by utilizing idle times for transmission / reception to measure the electric field strength; and a means that increments / decrements an interference counter provided to each standby frequency carrier on the basis of the magnitude comparison between the electric field strength and a threshold value to discriminate exchangeable standby frequency carriers on the basis of the count, sequentially searches the exchangeable frequency carrier from the top of the standby list and exchanges the exchangeable frequency carriers, the means adding the exchanged carriers to the tail end of the standby list and starting monitoring after initializing the count to a greater count value so that the carrier is reused after sufficiently confirming the carrier communicationable. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a frequency hopping communication apparatus in which a use carrier is switched according to a predetermined hopping pattern.
[0002]
[Prior art]
The 2.4 GHz band ISM band is used by various devices and is a frequency band in which interference easily occurs. Even when a spread spectrum wireless communication apparatus (hereinafter referred to as an FHSS communication apparatus) using a frequency hopping method, which is considered to be relatively resistant to interference, performs communication in this frequency band, a specific frequency carrier (hereinafter referred to as a carrier) interferes for a certain period of time. If it is received, it hops to the specific carrier at a fixed period, and thus interference is received.
[0003]
In order to avoid this interference, all the carriers are classified into two: a carrier that is used as a hopping pattern and a spare carrier that is not used, and it is detected that the carrier being used as a hopping pattern is subject to interference from interfering waves. Then, a communication device has been proposed in which the carrier is deleted from the hopping pattern and a spare carrier is added to the hopping pattern (see Patent Document 1). Hereinafter, a conventional frequency hopping communication apparatus will be described with reference to FIG.
[0004]
As shown in FIG. 8, the conventional frequency hopping communication apparatus has a frequency slot switching unit 804 for switching frequency slots (carriers) according to a frequency hopping pattern. In this frequency slot switching unit 804, the monitoring unit 810 monitors the reception state of the frequency slot being used as the frequency hopping pattern. In step 811, the frequency slot is deleted from the hopping pattern table 813, and the change is output to the transmission data transmission path 805 in order to transmit the change contents to the communication partner using the transmission idle time.
[0005]
As a result, the faulty frequency slot is deleted from the frequency hopping pattern, thereby improving the reliability of communication and preventing the transmission speed from being lowered.
[0006]
[Patent Document 1]
JP-A-7-107010 [0007]
[Problems to be solved by the invention]
However, since the wireless environment changes during communication, various carriers may be interfered by interference waves during that time. In the conventional FHSS communication apparatus, when the same number of carriers as the number of spare carriers is exchanged from the start of communication, the carriers cannot be exchanged thereafter, and it becomes difficult to maintain communication quality. .
[0008]
The present invention solves the above-described problem, and a carrier that has been deleted from a hopping pattern due to interference of an interfering wave can be reused as a replaceable carrier depending on the monitoring result of the subsequent reception state. It is an object of the present invention to provide an FHSS communication apparatus that can maintain communication quality in response to various environmental changes.
[0009]
[Means for Solving the Problems]
In order to achieve this object, the FHSS communication apparatus according to the present invention provides a condition that enables replacement for a carrier that has been deleted from the hopping pattern due to interference of an interfering wave, as compared to other spare carriers. The lower priority given to the hopping pattern is lower than that of other spare carriers, so that the carrier can be reused as a replaceable carrier after sufficiently confirming that the carrier has become communicable. It is a thing.
[0010]
According to the present invention, it is possible to provide an FHSS communication apparatus that can always maintain stable communication quality even during long-time communication.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
The invention according to claim 1 of the present invention monitors the spare carrier by measuring the electric field strength of the carrier in the spare frequency carrier list, and according to the frequency at which the electric field strength exceeds a predetermined threshold value. When the interference counter of the backup frequency carrier is increased or decreased, and one of the used carrier and the backup carrier that has been disturbed in the hopping pattern is exchanged, the frequency that the threshold is exceeded is least due to the order of the value of the interference counter. Replace the used carrier that has been disturbed in order from the carrier of the spare frequency, and the carrier deleted from the hopping pattern has the worst value as the initialization value of the interference counter (the state where the frequency that the electric field strength exceeds the threshold continues to be high) Frequency hopping communication, characterized by setting the interference counter to reach the maximum or minimum value) With this configuration, the monitoring of the carrier deleted from the hopping pattern is started from the worst value of the interference counter value, so that the frequency at which the electric field strength measured for that frequency exceeds the threshold is sufficiently high. Until it drops, it will wait in a non-exchangeable state, and it can be exchanged after the interference counter for that carrier frequency reaches the best value, that is, after fully confirming that the carrier can communicate Since it is reused as a reliable carrier, it has the effect of constantly maintaining stable communication quality in response to various changes in the wireless environment during long-time communication.
[0012]
The invention according to claim 2 of the present invention adds another carrier that has been subjected to interference from a disturbing wave and has been exchanged for a spare carrier to the tail of the spare carrier list, so that the priority of using the carrier as another hopping carrier can be increased. 2. The frequency hopping communication apparatus according to claim 1, wherein the frequency hopping communication apparatus is configured to be lower than a spare carrier, and avoids immediately reusing a carrier deleted from a hopping pattern due to interference and degrading radio quality. , Has the effect of maintaining stable communication quality.
[0013]
According to the third aspect of the present invention, the electric field strength of the used carrier is measured during communication, and the threshold value for increasing / decreasing the interference counter of each spare carrier is adjusted according to the change in the electric field strength of the used carrier. The frequency hopping communication apparatus according to claim 1, wherein the frequency hopping communication apparatus according to claim 1, wherein when the measured electric field strength is large, the threshold value is increased to make it easier to determine that the spare carrier can be replaced. If it is small, the threshold can be lowered to make it easier to determine that the spare carrier cannot be replaced. Therefore, it is possible to increase the number of spare carriers that can be replaced or to avoid meaningless carrier replacement. Thus, the carrier can be exchanged efficiently.
[0014]
The invention according to claim 4 of the present invention is characterized in that a threshold value for increasing / decreasing the interference counter of each spare carrier is calculated from an average value of the past N times of the electric field strength of the carrier used. The frequency hopping communication apparatus according to Item 3, which has an effect of calculating a threshold value that is not influenced by an electric field strength that changes greatly by chance, for example, when a physical radio wave shield temporarily crosses.
[0015]
The invention according to claim 5 of the present invention is a more recent method for calculating the average value of the electric field strength of the carriers used, which is used for calculating a threshold value for increasing or decreasing the interference counter of each spare carrier. 5. The frequency hopping communication apparatus according to claim 4, wherein the weighting is performed so that the value of the measured electric field strength is largely reflected. It has the effect that a threshold value that can follow the change in electric field strength due to the physical movement of can be set.
[0016]
(Embodiment 1)
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS.
[0017]
FIG. 1 is a configuration diagram of an FHSS communication apparatus showing one embodiment. As shown in FIG. 1, the FHSS communication apparatus includes a hopping pattern table 108 that manages carriers used for hopping and their reception states, a frequency switching unit 105 that sequentially switches carriers that communicate according to the hopping pattern, and a hopping pattern. The used carrier monitoring means 104 for monitoring the reception state of the carrier in use, the spare carrier electric field strength measuring means 102 for measuring the electric field strength of the spare carrier using the transmission / reception idle time, and the measurement result are set. A replacement carrier determination unit 106 that determines whether the spare carrier is replaceable based on a comparison with a threshold value, a spare carrier list table 109 that manages the exchange priority of all spare carriers, a hopping pattern table, and a spare carrier list table More carrier exchange control That the hopping pattern control unit 107, a transmission unit 103 for transmitting a carrier exchange information to the communication partner, and a radio section 101 Metropolitan or perform the transmission and reception of the communication partner and data or to establish a radio link.
[0018]
The operation of the FHSS communication apparatus configured as described above will be described. FIG. 2 shows processing in a process until it is determined that the spare carrier is a replaceable / non-exchangeable carrier. FIG. 3 shows a spare carrier list table at the start of communication. Each spare carrier has an interference counter initialized to “1”. In the FHSS communication apparatus that performs communication using time division multiplexing processing, there is a time during which neither transmission nor reception is performed, and reception operations are sequentially performed from the head of the spare carrier list using the idle time (FIG. 2: 201, 202). Since the communication partner cannot perform transmission processing in spare time and with a spare carrier, the radio wave received by this reception processing is an interference wave emitted by another wireless device.
[0019]
The spare carrier electric field strength measuring means 102 measures the electric field strength at the time of reception (FIG. 2: 203) and compares it with a preset threshold value of electric field strength (FIG. 2: 204). Even if it is used, it is determined that communication is difficult due to interference of the interference wave, and the interference counter of the spare carrier is incremented (FIG. 2: 205). On the contrary, if it is small, it is determined that the spare carrier will not be interfered by interference even if it is used, and the interference counter of the spare carrier is decremented (if it is not “0”) (FIG. 2: 206). When the carrier is exchanged, a carrier whose interference counter value is “0” is a replaceable carrier, and a carrier whose value is not “0” is a non-exchangeable carrier.
[0020]
FIG. 6 shows processing at the time of carrier exchange. FIG. 4 shows a hopping pattern table at the start of a call, and each used carrier has an error counter initialized to “0”. FIG. 5 shows changes in the spare carrier list table and the hopping pattern table before and after the carrier exchange.
[0021]
When communicating by sequentially switching the communication carrier according to the hopping pattern table to be shared with the communication partner, when using the carrier monitoring unit 104 detects a receiving error (Figure 6: 602), increments the error counter for that use carrier f _n If it is normal reception, the error counter is initialized to “0” (FIG. 6: 610). At that time, if the error counter value is “2” or more, that is, if a continuous reception error has occurred (FIG. 6: 605), it is determined that the used carrier f _n has received interference from the interference wave, and the carrier shift operation is started. . Search is made in order from the beginning of the spare carrier list table, and when the replaceable carrier _fr is found, the search is terminated, and the spare carrier _fr is deleted from the spare carrier list as a candidate carrier for exchange (FIG. 6: 608). At that time, the hopping pattern control unit 107 replaces _fr with the position where f _{n of the} hopping pattern table exists (FIG. 6: 607), and initializes its error counter to “0”. The f _n added to the end of the preliminary carrier list table, is initialized to "3" to the interference counter.
[0022]
The transmission means 103 transmits a carrier exchange request to the communication partner using the control field at the time of transmission at the next hopping frequency f _{n + 1} (FIG. 6: 609), and the response from the communication partner at the time of reception at f _{n + 1.} Check. When the response cannot be confirmed due to a reception error (FIG. 6: 604), or when the communication partner does not return a response due to a reception error (FIG. 6: 612), at the next hopping frequency f _{n + 2} The same process is performed when sending and receiving.
[0023]
(Embodiment 2)
Hereinafter, Embodiment 2 of the present invention will be described with reference to FIG.
[0024]
FIG. 7 is a block diagram of the FHSS communication apparatus showing one embodiment. As shown in FIG. 7, in the configuration of the first embodiment, used carrier electric field strength measuring means 710 and threshold value calculating means 711 are provided.
[0025]
The operation of the FHSS communication apparatus configured as described above will be described. When communication is performed by sequentially switching communication carriers in accordance with a hopping pattern table shared with a communication partner, the used carrier monitoring means 704 monitors reception errors / normal reception, and the used carrier electric field strength measuring means 710 only receives the normal reception. Measure the field strength. Whether or not communication is possible in an environment depends on the relative field strength value of the relative interference wave rather than the absolute field strength value of the absolute interference wave (if the communication carrier is close and the field strength of the communication carrier is high, (Even if the electric field strength of the jamming wave is somewhat high, communication is possible. Conversely, if the communication carrier has a low electric field strength, such as a long communication distance, communication is difficult even if the electric field strength of the jamming wave is as low as possible.) The threshold calculation means 711 sets the “difference” between the electric field strength of the communication carrier and the electric field strength of the interference wave in advance so that communication is possible, and the measured electric field strength of the communication carrier Threshold value is calculated from “difference”. This threshold value is used as a threshold value of the electric field strength for determining whether or not the spare carrier can be exchanged in the first embodiment.
[0026]
As the threshold value calculation method of the threshold value calculation means 711, if the method of calculating the threshold value from the average value of the past N times is selected by storing N field strengths of communication carriers, the physical value can be obtained. It is possible to calculate a threshold that is not influenced by the electric field strength that changes greatly by chance, for example, when a radio wave shield temporarily crosses.
[0027]
As another calculation method, when the measured electric field strength is R, the average value so far is A, and the weight is W, (A × W) / (W + 1) + R / (W + 1) is calculated as an average value. Therefore, if a method of weighting is selected so that the value of the electric field strength measured more recently is greatly reflected, the actual physical movement can be suppressed while suppressing the influence of a large change in electric field strength that occurs by chance. It is possible to set a threshold value that can follow the change in electric field strength due to the.
[0028]
【The invention's effect】
As is clear from the above description, according to the present invention, even if the carrier used as the hopping pattern is subjected to interference with the interference wave and exchanged with the spare carrier, it is received as the spare carrier with the lowest priority thereafter. By continuing to monitor the status, it is possible to re-use the carrier as a replaceable carrier after sufficiently confirming that the carrier has become communicable. Correspondingly, it has an effect of constantly maintaining stable communication quality.
[0029]
In addition, by measuring the electric field strength of the carrier used during communication and dynamically changing the threshold for increasing / decreasing the interference counter of each backup carrier according to the change in the electric field strength of the carrier used, The number of possible spare carriers can be increased, meaningless carrier exchange can be avoided, and the carrier can be exchanged efficiently.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of an FHSS communication apparatus according to an embodiment of claim 1 of the present invention; FIG. 2 is a flowchart showing reception processing on a spare carrier in the embodiment; FIG. 4 is a hopping pattern table diagram at the start of a call in the same embodiment. FIG. 5 is a transition diagram of the spare carrier list table and the hopping pattern table before and after carrier exchange in the same embodiment. 6 is a flowchart showing processing at the time of carrier exchange in the same embodiment. FIG. 7 is a block diagram of an FHSS communication apparatus in an embodiment of claim 2 of the present invention. FIG. 8 is a block diagram of a conventional FHSS communication apparatus. Explanation of]
DESCRIPTION OF SYMBOLS 101 Radio | wireless part 102 Reserve carrier electric field strength measurement means 103 Transmission means 104 Use carrier monitoring means 105 Frequency switching part 106 Exchange carrier determination part 107 Hopping pattern control part 108 Hopping pattern table 109 Reserve carrier list table

Claims (6)

Monitor the spare carrier by measuring the field strength of the carrier in the spare frequency carrier list,
Increase or decrease the interference counter of the backup frequency carrier according to the frequency that the electric field strength exceeds a predetermined threshold,
When exchanging one of the interfered use carrier and the spare carrier in the hopping pattern, the use carrier that is obstructed in order from the carrier having the least frequent frequency exceeding the threshold value due to the order of the value of the interference counter. The frequency hopping communication apparatus is characterized in that the carrier deleted from the hopping pattern is set to the worst value as the initialization value of the interference counter. A carrier that has been interfered by interference and exchanged with a spare carrier is added to the tail of the spare carrier list, so that the priority of using it again as a hopping carrier is made lower than other spare carriers. Item 4. A frequency hopping communication apparatus according to Item 1. Measure the electric field strength of the carrier used during communication, and dynamically change the threshold for increasing or decreasing the interference counter of each spare carrier according to the change in the electric field strength of the carrier used, The frequency hopping communication apparatus according to claim 1. 4. The frequency hopping communication apparatus according to claim 3, wherein a threshold value for increasing / decreasing an interference counter of each spare carrier is calculated from an average value of past N field strengths of used carriers. As a calculation method of the average value of the electric field strength of the carriers used, which is used to calculate the threshold value for increasing / decreasing the interference counter of each spare carrier, the electric field strength value measured more recently is greatly reflected. The frequency hopping communication apparatus according to claim 4, wherein a weight is assigned to the frequency hopping communication apparatus. Measures the electric field strength of the carrier in the backup frequency carrier list using the idle time of transmission and reception during communication, and increments the interference counter of the backup frequency carrier whenever the electric field strength exceeds a predetermined threshold, If the electric field strength does not exceed a predetermined threshold, the interference counter is decremented, the spare carrier is judged to be replaceable / impossible based on the value of the interference counter, and the replaceable carrier is searched in order from the head of the spare list. A frequency hopping communication device that suppresses interference by exchanging with a carrier used that has been interfered by interference waves,
The carrier deleted from the hopping pattern initializes the counter to a large value, monitors it as a spare carrier,
A frequency hopping communication apparatus characterized by reusing as a replaceable carrier after sufficiently confirming that the carrier is communicable.

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