WIRELESS COMMUNICATION SYSTEM, WIRELESS COMMUNICATION METHOD AND TERMINAL DEVICE
An aspect of the present invention provides a wireless communication system including: one or more terminal devices that transitions between a first state in which a wireless signal can be intermittently detected and a second state in which a wireless signal can be transmitted and received; and a gateway device that transmits an instruction frame instructing the one or more terminal devices to transition to the second state at a predetermined transmission interval. Each of the one or more terminal devices includes: an instruction frame detector that detects the instruction frame at a detection interval longer than an interval at which the gateway device transmits the instruction frame; a preamble signal detector that detects a preamble signal at a predetermined time interval and a predetermined frequency channel when the instruction frame is detected; and a control unit that causes a subject terminal device to transition from the first state to the second state based on a detection result of one or more preamble signals in one or more frequency channels.
1 . A wireless communication system comprising:
one or more terminal devices configured to transition between a first state in which a wireless signal can be intermittently detected and a second state in which a wireless signal can be transmitted and received; and
a gateway device configured to transmit an instruction frame instructing the one or more terminal devices to transition to the second state at a predetermined transmission interval, wherein
each of the one or more terminal devices includes:
an instruction frame detector configured to detect the instruction frame at a detection interval longer than an interval at which the gateway device transmits the instruction frame;
a preamble signal detector configured to detect a preamble signal at a predetermined time interval and a predetermined frequency channel when the instruction frame is detected; and
a control unit, including one or more processors, configured to cause a subject terminal device to transition from the first state to the second state based on a detection result of one or more preamble signals in one or more frequency channels.
2 . The wireless communication system according to claim 1 , wherein when a detection signal sequence based on the preamble signal detected for one or more frequency channels matches a predetermined signal sequence unique to the subject terminal device, the control unit is configured to cause the subject terminal device to transition from the first state to the second state.
3 . The wireless communication system according to claim 2 , wherein the control unit is configured to determine the detection signal sequence before the instruction frame is received or demodulated, and to determine whether or not to receive the instruction frame based on the determination result.
4 . The wireless communication system according to claim 3 , further comprising:
a frame receiver configured to receive and demodulate an instruction frame detected during one detection interval when a detection signal sequence detected in the one detection interval matches the unique signal sequence and to not receive or demodulate the instruction frame when the detection signal sequence does not match the unique signal sequence.
5 . The wireless communication system according to claim 2 , wherein
the unique signal sequence is generated based on setting information regarding generation, transmission, reception, or detection of frames by the terminal device, and
the preamble signal transmitted in a predetermined order of frequency channels is generated so that a signal sequence arranged in the transmission order becomes the unique signal sequence.
6 . The wireless communication system according to claim 1 , wherein
when the instruction frame is detected, the preamble signal detector is configured to attempt to detect the preamble signal for a predetermined channel in a predetermined order.
7 . A wireless communication method in a wireless communication system comprising:
one or more terminal devices configured to transition between a first state in which a wireless signal can be intermittently detected and a second state in which a wireless signal can be transmitted and received; and
a gateway device configured to transmit an instruction frame instructing the one or more terminal devices to transition to the second state at a predetermined transmission interval, wherein
each of the one or more terminal devices executes:
detecting the instruction frame at a detection interval longer than an interval at which the gateway device transmits the instruction frame;
detecting a preamble signal at a predetermined time interval and a predetermined frequency channel when the instruction frame is detected; and
causing a subject terminal device to transition from the first state to the second state based on a detection result of one or more preamble signals in one or more frequency channels.
8 . A terminal device in a wireless communication system comprising:
one or more terminal devices configured to transition between a first state in which a wireless signal can be intermittently detected and a second state in which a wireless signal can be transmitted and received; and
a gateway device configured to transmit an instruction frame instructing the one or more terminal devices to transition to the second state at a predetermined transmission interval, each of the terminal devices comprising:
an instruction frame detector configured to detect the instruction frame at a detection interval longer than an interval at which the gateway device transmits the instruction frame;
a preamble signal detector configured to detect a preamble signal at a predetermined time interval and a predetermined frequency channel when the instruction frame is detected; and
a control unit, including one or more processors, configured to cause a subject terminal device to transition from the first state to the second state based on a detection result of one or more preamble signals in one or more frequency channels.
9 . The wireless communication method according to claim 7 , comprising:
when a detection signal sequence based on the preamble signal detected for one or more frequency channels matches a predetermined signal sequence unique to the subject terminal device, causing the subject terminal device to transition from the first state to the second state.
10 . The wireless communication method according to claim 9 , comprising:
determining the detection signal sequence before the instruction frame is received or demodulated, and determining whether or not to receive the instruction frame based on the determination result.
11 . The wireless communication method according to claim 10 , wherein:
a frame receiver is configured to receive and demodulate an instruction frame detected during one detection interval when a detection signal sequence detected in the one detection interval matches the unique signal sequence and to not receive or demodulate the instruction frame when the detection signal sequence does not match the unique signal sequence.
12 . The wireless communication method according to claim 9 , wherein
the unique signal sequence is generated based on setting information regarding generation, transmission, reception, or detection of frames by the terminal device, and
the preamble signal transmitted in a predetermined order of frequency channels is generated so that a signal sequence arranged in the transmission order becomes the unique signal sequence.
13 . The wireless communication method according to claim 7 , comprising:
when the instruction frame is detected, attempting to detect the preamble signal for a predetermined channel in a predetermined order.
14 . The terminal device in the wireless communication system according to claim 8 , wherein
when a detection signal sequence based on the preamble signal detected for one or more frequency channels matches a predetermined signal sequence unique to the subject terminal device, the control unit is configured to cause the subject terminal device to transition from the first state to the second state.
15 . The terminal device in the wireless communication system according to claim 14 , wherein
the control unit is configured to determine the detection signal sequence before the instruction frame is received or demodulated, and to determine whether or not to receive the instruction frame based on the determination result.
16 . The terminal device in the wireless communication system according to claim 15 , further comprising:
a frame receiver configured to receive and demodulate an instruction frame detected during one detection interval when a detection signal sequence detected in the one detection interval matches the unique signal sequence and to not receive or demodulate the instruction frame when the detection signal sequence does not match the unique signal sequence.
17 . The terminal device in the wireless communication system according to claim 14 , wherein
the unique signal sequence is generated based on setting information regarding generation, transmission, reception, or detection of frames by the terminal device, and
the preamble signal transmitted in a predetermined order of frequency channels is generated so that a signal sequence arranged in the transmission order becomes the unique signal sequence.
18 . The terminal device in the wireless communication system according to claim 8 , wherein
when the instruction frame is detected, the preamble signal detector is configured to attempt to detect the preamble signal for a predetermined channel in a predetermined order.