Asynchronous interference avoiding method and asynchronous interference avoiding system
First Claim
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1. An asynchronous interference avoiding method in a network comprising:
- a first step wherein a slave station, which can temporarily serve as a master station (a temporary master station), in the slave station interposition-type network receives a collision control downward packet from a first temporary master station, which temporarily serves as a master station, and judges whether or not a unique word for synchronization contained in the collision control downward packet is detected;
a second step wherein, when the slave station could not have detected the unique word in the first step as a result of interference caused by the send of the collision control downward packet from the first temporary master station and a second temporary master station as another temporary master station in different timing, the slave station counts the number of times of unique word undetection;
a third step wherein, when the number of times of receive of the collision control downward packet and the number of times of unique word undetection have exceeded or have become equal to respectively preset thresholds, the slave station judges, that asynchronous interference with the first temporary master station has taken place, stops an attempt to synchronize with the first temporary master station, temporarily functions as a third temporary master station, and performs send/receive in slot timing of the third temporary master station;
a fourth step wherein the third temporary master station searches slots in all frequencies being used for a slot, which exceeds or is equal to a preset threshold and has the highest-receive field strength, and judges whether or not the slot meeting the requirements has been detected;
a fifth step wherein, when the slot meeting the requirements has been detected in the fourth step, the third temporary master station judges that the slot is one in interference with the first temporary master station, followed by the send of an interference detection packet through a send slot corresponding to the detected slot in a continuous manner by the number of times which exceeds or is equal to a preset threshold;
a sixth step wherein, when the interference detection packet from the third temporary master station has been sent in the same timing as the receive slot in the first temporary master station or the second temporary master station, the first temporary master station or the second temporary master station recognizes the receive of the interference detection packet and hops to a channel, which has been computed using random numbers, to avoid the interference of the collision control downward packet; and
a seventh step wherein, when the first temporary master station has hopped to a new channel in the sixth step, the third temporary master station hops to a channel corresponding to the channel of the first temporary master station, is returned in its function to the slave station, and receives the collision control downward packet from the first temporary master station.
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Abstract
In a network that roughly comprises a temporary master station and a plurality of slave stations and is an adhoc network, which can be immediately constructed in situ, and is a temporary master station interposition-type network in which a temporary master station is present, the temporary master station receives and judges an interference detection packet sent from the slave station. By virtue of this construction, an asynchronous interference avoiding method and an asynchronous interference avoiding system can be realized which can reliably avoid interference.
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Citations
20 Claims
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1. An asynchronous interference avoiding method in a network comprising:
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a first step wherein a slave station, which can temporarily serve as a master station (a temporary master station), in the slave station interposition-type network receives a collision control downward packet from a first temporary master station, which temporarily serves as a master station, and judges whether or not a unique word for synchronization contained in the collision control downward packet is detected;
a second step wherein, when the slave station could not have detected the unique word in the first step as a result of interference caused by the send of the collision control downward packet from the first temporary master station and a second temporary master station as another temporary master station in different timing, the slave station counts the number of times of unique word undetection;
a third step wherein, when the number of times of receive of the collision control downward packet and the number of times of unique word undetection have exceeded or have become equal to respectively preset thresholds, the slave station judges, that asynchronous interference with the first temporary master station has taken place, stops an attempt to synchronize with the first temporary master station, temporarily functions as a third temporary master station, and performs send/receive in slot timing of the third temporary master station;
a fourth step wherein the third temporary master station searches slots in all frequencies being used for a slot, which exceeds or is equal to a preset threshold and has the highest-receive field strength, and judges whether or not the slot meeting the requirements has been detected;
a fifth step wherein, when the slot meeting the requirements has been detected in the fourth step, the third temporary master station judges that the slot is one in interference with the first temporary master station, followed by the send of an interference detection packet through a send slot corresponding to the detected slot in a continuous manner by the number of times which exceeds or is equal to a preset threshold;
a sixth step wherein, when the interference detection packet from the third temporary master station has been sent in the same timing as the receive slot in the first temporary master station or the second temporary master station, the first temporary master station or the second temporary master station recognizes the receive of the interference detection packet and hops to a channel, which has been computed using random numbers, to avoid the interference of the collision control downward packet; and
a seventh step wherein, when the first temporary master station has hopped to a new channel in the sixth step, the third temporary master station hops to a channel corresponding to the channel of the first temporary master station, is returned in its function to the slave station, and receives the collision control downward packet from the first temporary master station. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 14, 15, 16, 17, 18, 19, 20)
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12. A system for avoiding asynchronous interference in a network, comprising:
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a TDMA-TDD processor for performing processing regarding TDMA-TDD;
a clock section for generating a periodic pulse signal which is sent to an RF section and the TDMA-TDD processor;
an adhoc protocol processor for processing a protocol used in an adhoc network;
a storage for the number of receive packets, for counting and storing received packets;
a storage for the number of times of unique word undetection, for storing the number of times of undetection of a unique word of a collision control downward packet sent from a temporary master station of the network;
a storage for the number of times of error detection, for storing the number of times of detection of an error in the received packet;
a hop destination channel computing section which generates random numbers to compute a channel to which next hopping is performed; and
a plurality of slave stations which can temporarily perform the operation of the temporary master station, wherein when the TDMA-TDD processor has detected the unique word for synchronization of the temporary master station with the slave station, and, when the number of times of receive of the collision control downward packet in the storage for the number of receive packets and the number of times of detection of an error in received packet in the storage for the number of times of error detection have exceeded or have become equal to respective preset thresholds, the adhoc protocol processor judges that interference has taken place between a first temporary master station and a second temporary master station as another temporary master station among the temporary master stations which send information to the slave station, while, when the TDMA-TDD processor in the slave station cannot detect the unique word and when the number of times of receive of the collision control downward packet in the storage for the number of receive packets and the number of times of unique word undetection in the storage for the number of times of unique word undetection have exceeded or have become equal to respective preset thresholds, the adhoc protocol processor judges that interference has taken place between the first temporary master station and the slave station, the TDMA-TDD processor, based on the judgment, made by the adhoc protocol processor, such that interference has taken place between the first temporary master station and the second temporary master station, sends a channel switching request packet to the first temporary master station and the second temporary master station through the RF section for performing the send/receive of radio waves, modulation, and demodulation, while, based on the judgment, made by the adhoc protocol processor, such that interference has taken place between the first temporary master station and the slave station, the slave station temporarily functions as a third temporary master station which continuously sends, by the preset number of times, an interference detection packet through a send slot corresponding to a slot, among slots in all frequencies being used, which exceeds or is equal to a preset threshold and has the highest-receive field strength, the hop destination channel computing section, based on the channel switching request packet received by the first temporary master station and the second temporary master station, generates random numbers to compute a channel to which next hopping is performed, while, in the first temporary master station or the second temporary master station, upon judgment on the receive of the interference detection packet, or upon judgment on undetection of the unique word of the interference detection packet, or upon judgment of the interference detection packet as an error packet, in which an error has been detected, in order to avoid interference, the hop destination channel computing section generates random numbers to compute a channel to which next hopping is performed, and the third temporary master station, when the first temporary master station has performed channel hopping, hops to a channel corresponding to the channel of the first temporary master station and then returns in its function to the slave station to again receive, as the slave station, the collision control downward packet from the first temporary master station. - View Dependent Claims (13)
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Specification