JP2009044383A - Information communication terminal, radio communication equipment, and wireless communication network - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce power consumption without affecting communication. <P>SOLUTION: The communication unit is set to a period for waiting for reception when the communication unit is being supplied with the power. The period for waiting for the reception includes a sleep period for stopping supply of the clock from the clock circuit and a wake period for supplying the clock from the clock circuit. The sleep period and the wake period are alternately repeated. The information communication terminal changes a length of the wake period when a period during which the Beacon frame cannot be received continues for a predetermined period. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an information communication terminal, a wireless communication apparatus, and a wireless communication network, and more particularly, to an information communication terminal, a wireless communication apparatus, and a wireless communication network that can perform communication in accordance with usage.

  In recent years, wireless communication that does not use a base station (access point) is spreading in a plurality of information communication terminals. Note that a network composed of only terminals capable of such wireless communication is called an ad hoc network.

Various technologies related to terminals capable of communication in an ad hoc network are disclosed. For example, Patent Document 1 discloses a portable communication device that can easily exchange data between an unspecified number of people.
JP 2000-1115012 A

  In Patent Document 1 described above, in order to allow an unspecified number of people to exchange messages with each other, each portable communication device basically repeats its own message transmission at intervals of 5 seconds. ing. It is disclosed that when such message transmission is repeated, when an energy saving mode (an operation mode with a long transmission interval) or a sleep mode (pause) is detected, the mode is shifted to the energy saving mode or the sleep mode. In this mode, the transmission interval is lengthened, one of transmission or reception is stopped, the transmission radio wave is weakened, or it is operated intermittently. The conditions for shifting to these modes are predetermined. This is due to the presence or absence of reception within the time, and no technology for shifting to the energy saving mode or the sleep mode according to the period of waiting for reception is shown.

  In a wireless local area network (LAN) ad hoc network, each terminal is portable, and thus power consumption is required to be reduced. However, as described above, in the past, when the reception is always performed or when data cannot be received for a predetermined period, the mode is merely shifted to the sleep mode or the energy saving mode, and proposals have been made for more detailed measures for reducing power consumption. There wasn't.

  SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an information communication terminal, a wireless communication device, and a wireless communication network that can reduce power consumption without hindering communication.

  According to one aspect of the present invention, an information communication terminal includes: a communication unit that receives a frame transmitted from another information communication terminal; a power supply unit that supplies power to each circuit of the communication unit; and each circuit of the communication unit. A clock circuit for supplying a clock for operating the circuit.

  The communication unit is set to a reception standby period in which reception of a frame is waited in a state where power is supplied. The reception standby period includes a sleep period in which the clock circuit clock supply is stopped and a clock circuit clock supply. The sleep period and the wake period are alternately repeated, and the length of the wake period is changed when a period during which frames cannot be received continues for a predetermined period.

  Preferably, when the period during which frames cannot be received continues for a predetermined period, the wake period is lengthened.

  Preferably, in the reception standby period, a standby period composed of a sleep period and a wake period is repeated, and when the wake period is lengthened, the standby period is shortened.

  Preferably, based on the number of times that the standby period during which frames cannot be received is continuously repeated, it is detected that the period during which frames cannot be received has continued for a predetermined period.

  Preferably, the waiting period after shortening is calculated using predetermined default waiting period data and a random coefficient.

  Preferably, an information processing unit is further provided using a frame received by the communication unit during the standby period, and the length of the standby period is set according to a predetermined application program executed by the information processing unit.

  Preferably, in order to reduce power consumption, the standby period is lengthened and the wake period is shortened.

Preferably, the wireless network is an ad hoc communication network.
According to another aspect of the present invention, a wireless communication device mounted on an information communication terminal includes a communication unit that receives a frame transmitted from another information communication terminal, and a power supply unit that supplies power to each circuit of the communication unit And a clock circuit that supplies a clock for operating the circuit to each circuit of the communication unit.

  The wireless communication device is set to a reception standby period in which reception of a frame is waited in a state where power is supplied. The reception standby period includes a sleep period in which the clock circuit clock supply stops and a clock circuit clock supply. The sleep period and the wake period are alternately repeated, and when the period during which frames cannot be received continues for a predetermined period, the length of the wake period is changed.

  According to still another aspect of the present invention, a wireless communication network includes a first information communication terminal and a second information communication terminal that communicates with the first information communication terminal. A communication unit that receives a frame transmitted from the information communication terminal, a power supply unit that supplies power to each circuit of the communication unit, and a clock circuit that supplies a clock for operating each circuit of the communication unit to operate the circuit ,including.

  The communication unit is set to a reception standby period for waiting for reception of the frame in a state where power is supplied. The reception standby period includes a sleep period in which the clock circuit clock supply stops and a clock circuit clock supply. In addition, the sleep period and the wake period are alternately repeated. When the period during which frames cannot be received continues for a predetermined period, the length of the wake period is changed.

  According to the present invention, the reception standby period in which power is supplied includes the sleep period in which the clock is not supplied and does not operate, that is, power is not consumed, and the wake period in which the clock is supplied and the frame can be received. And are repeated alternately. Therefore, it is possible to reduce power consumption by providing a sleep period in which power is not consumed even though power is supplied. Then, by restarting the supply of the clock, it is possible to easily shift from the sleep period to the wake period and receive a frame.

  And when the period which cannot be received continues for a predetermined period, the length of a wake period can be changed and the probability that a frame can be received can be raised.

  Therefore, power consumption can be reduced without hindering communication.

Embodiments of a wireless communication network according to the present invention will be described below with reference to the drawings.
FIG. 1 is a diagram schematically showing an example of the configuration of an ad hoc network which is an embodiment of a wireless communication network of the present invention.

  First, referring to FIG. 1A, a network 10 includes terminals 1 to 4 which are an embodiment of an information communication terminal of the present invention. The network 10 is a wireless communication network (ad hoc network) that includes a plurality of information communication terminals and does not use a base station.

  In the network 10 of the present embodiment, a plurality of independent radio cells are formed using different IBSSIDs (Independent Basic Service Set IDentification). Specifically, communication is performed between the terminal 1 and the terminal 2 using a certain IBSSID (in FIG. 1, an example where “BSS # 1” is described as an example), and at the same time, Communication between the terminal 3 and the terminal 4 becomes possible using the IBSSID. In FIG. 1A, a radio cell formed by using “a certain IBSSID” is shown as a radio cell 11, and “another IBSSID” (in FIG. 1, “BSS # 2” is described as an example). The wireless cell formed by is described as a wireless cell 12.

  In the network 10 according to the present embodiment, the terminal 1 can communicate with the terminal 3 and the terminal 4 using “a certain IBSSID” (or another IBSSID). It is possible to communicate with the terminal 3 or the terminal 4 using “other IBSSID” (or another IBSSID). In FIG. 1B, the radio cell formed between the terminal 1 and the terminal 3 by using “BSS # 1” is shown as the radio cell 13, and “BSS # 3” (in FIG. 1). A wireless cell formed between the terminal 2 and the terminal 4 by using another example of IBSSID is shown as a wireless cell 14.

FIG. 2 is a diagram schematically illustrating a hardware configuration of the terminal 1 in FIG.
Referring to FIG. 2, terminal 1 mainly includes host system 100 and communication circuit 200. The host system 100 includes a CPU (Central Processing Unit) that controls the operation of the host system 100 as a whole. In the host system 100, various applications are executed. Each application program is stored in an HD (hard disk) 102. The host system 100 also includes a RAM (Random Access Memory) 103 serving as a work area for the CPU 101, a display 104 for displaying information, a speaker 105 for outputting sound, and inputs used for inputting information from outside such as keys and buttons. And an interface 107 for exchanging information with the communication circuit 200.

  The communication circuit 200 includes a baseband / MAC (Media Access Control) circuit 250, an RF (Radio Frequency) circuit 205, a balun 204, an antenna 203, EEPROMs (Electronically Erasable and Programmable Read Only Memory) 206 and 207, a power supply circuit 201, and , Including a clock circuit 202.

  The clock circuit 202 supplies a clock signal to the baseband / MAC circuit 250 and the RF circuit 205. The power supply circuit 201 controls power supply to the baseband / MAC circuit 250 and the RF circuit 205.

  The RF circuit 205 transmits and receives data via the antenna 203. A balun 204 is provided between the antenna 203 and the RF circuit 205.

  The baseband / MAC circuit 250 includes a CPU 251, an interface 252, an external bus controller 253, a program memory 254, a shared memory 255, a timer 256, a control MAC unit 257, an ADC (analog-digital converter) 258, and a DAC (digital-analog). converter) 259.

  The interface 252 is an interface to the host system 100. When the CPU 251 receives an instruction to transmit data to the network from the host system 100, the CPU 251 causes the interface 252 to retrieve the data stored in a memory (for example, the RAM 103) in the host system 100. The host system 100 generates data instructing transmission, stores the data in the memory, and then transmits the data transmission instruction to the communication circuit 200. The data extracted by the interface 252 is temporarily stored in the program memory 254 as data constituting the “user data body part” of the frame transmitted to the network.

  Then, the CPU 251 generates a frame to be transmitted to the network by adding various data including a MAC header and an FCS (Frame Check Sequence) to the data stored in the program memory 254, and the program memory 254 And the shared memory 255 sets a flag indicating that the frame has been generated. Here, a configuration of a Beacon frame, which is an example of a frame transmitted to the network, will be described with reference to FIG.

  FIG. 3 is a diagram showing a general configuration of a frame conforming to the IEEE 802.11 standard.

  Referring to FIG. 3, frame 300 includes a MAC header portion 310, a frame body portion 320, and an FCS portion 330.

  The MAC header section 310 includes a DA (Destination Address) 311, an SA (Source Address) 312, and an IBSSID 313. DA 311 is the destination address of the frame 300. SA 312 is a transmission source address of the frame 300. DA 311 and SA 312 are 6-byte MAC addresses. These addresses are stored in the EEPROM 206. The IBSSID 313 is network identification information for identifying an ad hoc network. In the present embodiment, the terminal 1 can use different IBSSIDs in data transmission according to the attribute of data to be transmitted (data requested to be transmitted from an application in the host system 100). Specifically, the value of IBSSID 313 constituting the MAC header section 310 is changed according to the attribute of data to be transmitted.

  The frame body part 320 includes a beacon frame body part 321 and a user data body part 322. The beacon frame body part 321 includes an SSID (Service Set Identifier). The SSID 3211 is, for example, information for specifying a network name, and is set as a character string of 32 bytes or less. The user data body unit 322 includes actual data to be communicated (data requested to be transmitted from an application executed in the host system 100). The user data body part 322 includes, for example, 1500 bytes of data.

  3 is a Beacon frame, the frame / body portion 320 includes data such as a beacon / frame / body portion. However, if the frame 300 is a frame for other purposes, -The data contained in the body part 320 is changed suitably.

The FCS unit 330 includes information (FCS) used for frame error detection.
Returning to FIG. 2, the transmission frame stored in the program memory 254 is sent to the DAC 259 by the control MAC unit 257, and then converted into analog data, via the RF circuit 205, the balun 204, and the antenna 203. And sent to the network.

  An operation when the communication circuit 200 receives data transmitted via a network will be described. The frame sent to the RF circuit 205 via the antenna 203 and the balun 204 is converted into digital data by the ADC 258 and then sent to the control MAC unit 257. The control MAC unit 257 performs error correction decoding after performing frame head detection and time and frequency synchronization processing on the frame converted into the digital signal. Then, the control MAC unit 257 further determines whether or not the DA 311 of the frame matches the MAC address of the communication circuit 200 stored in the EEPROM 206, and if it matches, the MAC header unit 310 and the FCS from the frame. After removing the part 330, the remaining data (frame body part 320) is transferred to the program memory 254. If it is determined that they do not match, the control MAC unit 257 discards the received frame.

  When the received frame / body unit 320 is stored in the program memory 254, the control MAC unit 257 sets a flag indicating that in the shared memory 255. In response to the flag being set, the CPU 251 sends the frame / body unit 320 stored in the program memory 254 to the host system 100 via the interface 252.

  The configuration of terminals 2 to 4 in FIG. 1 can be the same as the configuration of terminal 1 described with reference to FIG. 2, and therefore description thereof will not be repeated here.

  4 and 5 show the configurations of terminals STA1 and STA2 constituting the same radio cell in network 10. FIG. 4 and 5 are the same as the configuration of the terminal 1 shown in FIG. Here, in order to distinguish the configurations of the terminals STA1 and STA2, the reference numerals of the corresponding parts in FIG. 2 are given “1” in the fourth digit in the reference numerals of the parts of the terminal STA1 in FIG. In FIG. 14 and FIG. 15, similarly, in the terminal STA <b> 2 of 5, “2” in the fourth digit is assigned to the code to distinguish each part of both terminals. The terminal STA1 includes a communication circuit 2001 and a host system 1001, and the terminal STA2 includes a communication circuit 2002 and a host system 1002.

  In the present embodiment, it is assumed that communication is performed based on the IEEE 802.11 standard, which is one of wireless LAN (Local Area Network) standards, and power consumption of terminals in a wireless LAN ad hoc network is reduced. As a communication method for this purpose, a method called intermittent transmission / reception ad hoc mode is presented. Here, two terminals STA1, STA2, and STA3 constituting the same radio cell are assumed. Since the terminals STA1 and STA2 have the configuration shown in FIGS. 4 and 5, detailed description of the configuration is omitted. The terminal STA3 has a configuration similar to that shown in FIG.

  FIG. 6 is a diagram schematically showing the sequence of the intermittent transmission / reception ad hoc mode according to the present embodiment. Here, the intermittent transmission / reception ad hoc mode refers to transmission / reception of data from the time when the communication circuit 200 is turned on by the power supply circuit 201 to supply power to each unit and then turned off (the power supply to each unit is cut off). This refers to a mode in which a transmission / reception operation is intermittently performed during a period in which transmission is possible. Therefore, between the time when the power is turned on and the time when the power is turned off (this is referred to as a reception standby period in which reception is waited), the communication circuit 200 has a sleep period (shown by a broken line in FIG. 6) and a wake period (see FIG. 6). 6 is shown alternately, and transmission and reception are possible in the wake period.

  In the wake period, the clock circuit 202 supplies a clock to each part of the communication circuit 200. Since each unit operates by receiving power supplied from the power supply circuit 201 during a period in which the clock is supplied, the power is consumed by each unit. In this state, data can be transmitted and received.

  When shifting from the wake period to the sleep period, the clock circuit 200 is instructed to be OFF by the CPU 251. When the clock circuit 200 is instructed to be turned off, the clock circuit 200 stops outputting the clock to each unit except the timer 255. As a result, the clock is not supplied to each part of the communication circuit 200 except the timer 255. Each unit cannot operate (stops) during a period when the supply of the clock is stopped. As a result, data transmission / reception is impossible because each unit stops operating during the sleep period, but power consumption can be saved because there is no power consumption in each unit except the timer 255.

  In the sleep period, the timer 256 performs a clock operation, and the timer 256 gives an ON instruction to the clock circuit 202 when measuring a certain sleep period. When the clock circuit 200 receives the ON instruction, the clock circuit 200 resumes the output of the clock to each part of the communication circuit 200 accordingly. Thereby, each part restarts operation | movement and consumption of electric power is restarted. As a result, the sleep period shifts to the wake period.

  In the wake period, the CPU 251 gives an OFF instruction to the clock circuit 202 when detecting that a certain wake period has elapsed based on the time value input from the timer 256. As a result, the communication circuit 200 shifts from the wake period to the sleep period.

  Referring to FIG. 6, when both terminals STA1 and STA2 are powered on, they enter a wake period and transmit a Beacon frame 300. The Beacon frame 300 has the format shown in FIG. 7A when it is transmitted from the terminal STA1, and has the format shown in FIG. 7B when it is transmitted from the terminal STA2. DA 311 of both Beacon frames 300 points to a destination that follows the broadcast.

  In FIG. 6, the terminal STA1 receives the Beacon frame 300 of FIG. 7 (B) transmitted from the terminal STA2 that has shifted to the third wake period in the fourth wake period after the power is turned on. Therefore, in response to the reception, a Beacon frame 300 (see FIG. 7C) having a confirmation response NULL in the MAC header section 310 is transmitted to the terminal STA2. In response to receiving the NULL Beacon frame 300, the terminal STA2 transmits the Beacon frame 300 (see FIG. 7D) having an ACK response to the MAC header B310. As a result, a session is established between the terminals STA1 and STA2 (the communication partner is confirmed and communication is possible with the confirmed communication partner), and the terminal STA1 has previously received from the host system 1001 side. A frame of data corresponding to the data transmission request is transmitted to the terminal STA2.

  8 and 9, when the intermittent transmission / reception ad hoc mode is implemented, the standby power (power consumption during standby) is obtained by the terminals STA1, STA2, and STA3 periodically shifting to the sleep period during the reception standby period. A reduction is schematically shown. In the state (1) of FIG. 8, the terminal STA3 is in the sleep period, but the Beacon frame 300 transmitted from the terminal STA1 in the wake period is received by the terminal STA2 in the wake period and a response is returned, and then the terminal A session is established between the STA and the STA 2 to perform data communication (see FIG. 9). And it transfers to the state (2) of FIG. During a data communication period, the terminal STA3 in the same radio cell operates to reduce power consumption by alternately repeating a wake period and a sleep period.

  In the state (2), in the period in which data communication is performed between the terminals STA1 and STA2, the terminal STA3 in the same radio cell is in the wake period.

  After the data communication is finished, in the state (3) of FIG. 8, the terminal STA3 in the wake period (the terminal STA2 is in the sleep period) receives the Beacon frame 300 transmitted from the terminal STA1, as shown in FIG. A response is transmitted and received between the two, a session is established, and data communication in the state (4) is performed. In this data communication period, the terminal STA2 in the same radio cell operates so as to reduce the power consumption by alternately repeating the wake period and the sleep period.

  FIG. 10 shows a system state transition model according to the present embodiment. In this transition model, the description about the clock stop state during Beacon frame transmission is omitted for the sake of simplicity. As shown in the figure, when the terminal is turned on, the system is set up. In this setting, a standby period (wake period + sleep period), data specifying the wake period, and the like are set. Thereafter, the process shifts to a standby period (start of the wake period), and the Beacon frame in the network 10 is monitored. When the Beacon frame cannot be received within the set fixed wake period (timeout), it shifts to the sleep period. When a certain sleep period ends (timeout), the process shifts to a standby period (start of the wake period), and the Beacon frame is monitored. When a Beacon frame is received during monitoring (Beacon detection), the session period (data transmission / reception) starts. When the data transmission / reception ends and the session period ends, the process shifts to a standby period (start of the wake period).

  The state transition of FIG. 10 is realized by referring to various parameters set in advance in the shared memory (2551, 2552). FIG. 11 shows various parameters stored in advance in the shared memory (2551, 2552). The parameters include waiting period data 280, wake period data 281, MAX waiting number data 282, count waiting number data 283, and default waiting period data 284. The storage area in which the data in FIG. 11 is stored is a storage area that can retain the stored contents even when the power supply from the power supply circuit 201 is cut off.

  The various parameters in FIG. 11 are input from the outside by operating the input units (1061, 1062) of the host system (1001, 1002) and stored in the shared memory (2551, 2552), or stored in the host system (1001, 1002). ) Is stored in the shared memory (2551, 2552) by the CPU (1011, 1012) in accordance with the application program to be executed in (1). Therefore, the data in the shared memory can be variably set by operating the input units (1061, 1062) or according to the type of application to be executed.

  Here, since an intermittent transmission / reception ad hoc mode between the terminals STA1 and STA2 is mainly assumed, these parameters are stored in the shared memories 2551 and 2552, as shown in FIG. 11, but the same applies to the terminal STA3. Stored in

  As shown in FIG. 12, the standby period includes a wake period and a sleep period. Therefore, it can be calculated from sleep period = standby period data 280−wake period data 281.

  The MAX waiting time data 282 indicates a threshold value for updating (changing) the waiting period data 280. Specifically, the standby period data 280 is changed (adjusted) when the Beacon frame cannot be received (detected) even if the standby (wake period) is repeated continuously for the number of times indicated by the MAX standby frequency data 282. The value indicated by the count standby count data 283 has a function of one type of counter that indicates the number of transitions to the standby period from when a Beacon frame is received until the next Beacon frame is received. The value of the count wait number data 283 is reset every time a Beacon frame is received. For example, it is updated to 0.

  The default waiting period data 284 is referred to in the calculation for updating the waiting period (ms) indicated by the waiting period data 280 as described later.

  As shown in FIG. 12, the wake period in the standby period is a period during which the Beacon frame can be received. For example, the emphasis is on increasing the Beacon frame receivability probability (Beacon frame detection rate). Then, the standby period (ms) indicated by the standby period data 280 is set short (shortened), and the wake period (ms) indicated by the wake period data 281 in the standby period is set long. On the other hand, if emphasis is placed on reducing the power consumption in the standby period, the standby period data 280 and the wake period data 281 are set so that the standby period (ms) is lengthened and the wake period is shortened.

  13 and 14 are diagrams for explaining variable setting (automatic adjustment) of the standby period. For example, as shown in FIG. 13, when the waiting period is fixed, the transmission completion cycle of the Beacon frame of the terminal STA1 and the cycle of starting the wake period in the terminal STA2 are the same (match) May occur. In that case, since the terminal STA2 cannot receive the Beacon frame 300 in the wake period, no session is established between the two, and no data communication is performed.

  On the other hand, when there is the automatic adjustment function of the waiting period in FIG. 14, for example, when the value of the count waiting number data 283 exceeds the value indicated by the MAX waiting number data 282 in the period indicated by the arrow 285. Since the period may be the same as described above, the waiting period (ms) indicated by the waiting period data 280 of the terminal STA2 is changed (updated). Thus, the period can be shifted, and at the timing indicated by the arrow 286 in FIG. 14, the transmission period of the Beacon frame 300 of the terminal STA1 matches the wake period of the terminal STA2, and the terminal STA2 receives information from the terminal STA1 side. The Beacon frame 300 can be received, and data communication can be performed between the two.

  In the present embodiment, the update of the standby period (ms) indicated by the standby period data 280 is performed by the CPU according to the calculation formula (1): (the post-update standby period = default standby period indicated by the default standby period data 284 + random coefficient). (2511, 2512) calculates a new waiting period, and stores the calculated waiting period as the waiting period data 280 of the shared memory (2551, 2552) (overwriting the waiting period data 280).

  The random coefficient used for calculating the standby period (ms) can be generated from the following parameters owned by the terminal 1. For example, the MAC address, the number of errors, the real-time clock (date and time) indicated by the clock circuit 202, and time data indicated by the hardware timer 256, and the like. Here, the number of errors refers to the total value of the number of times the waiting period (ms) has been updated in light of the MAX waiting number data 282.

  The intermittent transmission / reception ad hoc mode according to the sequence of FIG. 6 will be described with reference to the flowcharts of FIGS. 15 and 16. The flowcharts of FIG. 15 and FIG. 16 assume that communication is performed between the terminal STA1 and the terminal STA2. It is assumed that the power is turned on in advance and the storage of the data shown in FIG. 11 is completed in the shared memory 2552 (2552). Here, the count waiting time data 283 is initialized to 0.

  The operation during a period in which the terminal STA1 waits to receive the Beacon frame 300 via the network 10 while transmitting the Beacon frame 300 will be described with reference to FIG.

  First, when the power is turned on and the standby period is started, the CPU 2511 starts measuring the wake period in step SH10 based on the time measurement data input from the timer 2561. When the standby time starts, first, the wake period (wake mode) is entered. In step SH13, the passage of this wake period is timed (detected) by the CPU 2511 based on the timekeeping data of the timer 2561. The processing of this wake period will be described later with reference to FIG.

  When it is determined that the wake period has elapsed, the process shifts to the sleep period. In steps SH16 and SH19, as described above, the supply of the clock from the clock circuit 2021 is stopped, power is not consumed in each part, and transmission / reception is impossible. In addition, the timer 2561 measures the elapse of the sleep period.

  In step SH22, the timer 2561 compares the clocked value with the value of the sleep period, and if it is detected that the comparison result indicates (clocked value ≧ sleep period value) (YES in step SH22), the sleep period ends, that is, waits. It is determined that the period has ended, and the process proceeds to step SH25 described later. It is assumed that the value of the sleep period is calculated in advance according to (waiting period data 280−wake period data 281) using a value read from the shared memory 2551 by the CPU 2511 and is given to the timer 2561.

  Note that while it is determined that the comparison result indicates (timekeeping value <sleep period value) (NO in step SH22), it is detected that the standby period has not ended, and the processing in steps SH16, SH19, and SH22 is performed. Repeated.

  In step SH25, the timer 2561 gives an ON instruction to the clock circuit 2021, so that the clock circuit 2021 is restarted accordingly, and a clock signal is supplied to each unit so that transmission / reception is possible. At this time, when the input of the clock signal is resumed, the CPU 2511 increments (updates) the count standby count data 283 in the memory 2551 by 1 in step SH28.

  Thereafter, the CPU 2511 determines whether or not the value of the count standby count data 283 indicates a value greater than or equal to the value indicated by the MAX standby count data 282. Specifically, in step SH31, if it is not determined that the comparison result indicates (count standby count data 283 ≧ MAX standby count data 282) (NO in step SH31), the standby period data 280 is not changed. The series of processes ends, and the process shifts to a process for the next standby period.

  On the other hand, if it is determined that the comparison result indicates (standby count data 283 ≧ MAX standby count data 282) (YES in step SH31), the standby period changing process is performed in accordance with the above-described calculation formula (1) in step SH33. Calculated by the CPU 2511, the standby period data 280 of the shared memory 2551 is updated using the calculated value. Then, the CPU 2511 resets (0) the count standby count data 283 of the shared memory 2551 in step SH36. Thereafter, the series of processes ends, and the process proceeds to a process for the next standby period.

  With reference to FIG. 16, the wake period processing in step SH13 of FIG. 15 will be described. In the wake period, the control MAC unit 2571 of the terminal STA1 transmits a broadcast Beacon frame 300 in step SI10, and then determines whether any signal is received in step SI13.

  When it is determined that no signal is received (NO in step SI13), the control MAC unit 2571 notifies the CPU 2511 of that fact, and the CPU 2511, based on the time data input from the timer 2561, in step SI46, It is determined whether or not the process has ended. Specifically, the input timing data is compared with the wake period data 281 read from the shared memory 2551, and when it is determined that the comparison result indicates (input timing data ≧ wake period data 281), the wake period is terminated (step YES at SI46). And it transfers to the sleep period of step SH16 of FIG.

  If it is determined that the comparison result indicates (input timing data <wake period data 281) (NO in step SI46), the process returns to step SI10, and the Beacon frame 300 is transmitted.

  On the other hand, if it is determined that the Beacon frame 300 from the terminal STA1 is received via the network 10 (YES in step SI13, YES in SI16), in step SI19 and SI23, the above-described Beacon frame 300 of the NULL response is transmitted by the control MAC unit 2571. Is generated and the frame is transmitted to the terminal STA1. Thereafter, the process proceeds to step SI31, and it is determined whether or not the Beacon frame 300 of the ACK response is received from the counterpart terminal STA2.

  If the control MAC unit 2571 determines that a NULL response frame has been received (YES in step SI21), the control MAC unit 2571 generates and transmits the ACK response Beacon frame 300 in steps SI25 and SI28. Thereafter, the process proceeds to step SI43 described later.

  If control MAC unit 2571 determines that Beacon frame 300 of the ACK response has been received (YES in step SI31), if a data transmission request is input from host system 1001 (YES in SI33), step SI37 Based on the data provided from the host system 1001 in SI40, the control MAC unit 257 generates a data transmission frame. The generated frame of data is transmitted.

  On the other hand, if it is determined that the ACK Beacon frame 300 cannot be received from the terminal STA2 (NO in step SI31), it is determined whether a data frame has been received (step SI43). If the control MAC unit 2571 determines that a data frame has not been received (NO in step SI33), the process proceeds to step SI46 described above.

  If it is determined that the data frame has been received (YES in step SI43), the data in the data frame is temporarily stored in, for example, program memory 2541 in step SI44, and the received data stored in program memory 2541 is The data is transmitted to the host system 1001 side and processed on the host system 1001 side. If it is not determined that a data frame has been received (NO in step SI43), the process proceeds to step SI46.

  Although the processing during the standby period on the terminal STA1 side has been described here, the power consumption can be reduced by applying the same processing during the standby period also in the terminal STA2.

  According to the present embodiment, since a periodic sleep period (clock stop period) is provided during the transmission / reception standby period so that power is not consumed in each part of the communication circuit 200, the terminals STA1 and STA2 that are wireless LAN devices , STA3 power consumption can be reduced.

  In addition, when the clock supply to each unit is stopped during the sleep period and communication with other terminals cannot be performed, but the period during which communication cannot be performed continues for a certain time or longer, the sleep is performed using the above-described calculation formula (1). Since the period or the sleep cycle can be automatically changed in each terminal, it can be changed to the probability that the Beacon frame 300 can be received.

  Each embodiment disclosed this time must be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

It is a figure which shows typically an example of a structure of the ad hoc network which is embodiment of the radio | wireless communication network of this invention. It is a figure which shows typically the hardware constitutions of the terminal of FIG. It is a figure which shows typically the general structure of the flame | frame (Beacon frame) transmitted / received in the network of FIG. It is a block diagram of the terminal which concerns on embodiment. It is a block diagram of the terminal which concerns on embodiment. It is a figure which shows typically the sequence of the intermittent transmission / reception ad hoc mode which concerns on embodiment. (A)-(D) are figures which show an example of the flame | frame which concerns on embodiment. It is a figure which illustrates typically the communication procedure of the intermittent transmission / reception ad hoc mode which concerns on embodiment. It is a figure which illustrates typically the communication procedure of the intermittent transmission / reception ad hoc mode which concerns on embodiment. It is a figure which shows the system state transition model which concerns on embodiment. It is a figure explaining the various parameters which concern on embodiment. It is a figure explaining the setting function of the intermittent period which concerns on embodiment. It is a figure explaining the adjustment function of the intermittent period which concerns on embodiment. It is a figure explaining the adjustment function of the intermittent period which concerns on embodiment. It is a processing flowchart of the waiting period concerning an embodiment. It is a process flowchart of the wake period which concerns on embodiment.

Explanation of symbols

  1 to 4 terminals, 10 networks, 11 and 12 wireless cells, 100 host systems, 101 and 251 CPUs, 102 HD, 103 RAM, 104 displays, 105 speakers, 106 input units, 107 and 252 interfaces, 200 communication circuits, and 201 power supplies Circuit, 202 clock circuit, 203 antenna, 204 balun, 205 RF circuit, 206, 207 EEPROM, 250 baseband / MAC circuit, 253 external bus controller, 254 program memory, 255 shared memory, 256 timer, 257 control MAC unit, 258 ADC, 259 DAC, 280 wait period data, 281 wake period data, 282 MAX wait count data, 283 count wait count data, 284 default wait Period data, 300 frame.

Claims (10)

A communication unit that receives a frame transmitted from another information communication terminal;
A power supply unit that supplies power to each circuit of the communication unit;
A clock circuit for supplying a clock for operating the circuit to each circuit of the communication unit,
The communication unit is
In the state where the power is supplied, it is set to a reception waiting period for waiting for reception of the frame,
The reception standby period includes a sleep period in which the supply of the clock of the clock circuit is stopped and a wake period in which the clock of the clock circuit is supplied, and the sleep period and the wake period are alternately repeated,
An information communication terminal that changes a length of the wake period when a period during which the frame cannot be received continues for a predetermined period.   The information communication terminal according to claim 1, wherein the wake period is lengthened when a period during which the frame cannot be received continues for a predetermined period. In the reception standby period, a standby period consisting of the sleep period and the wake period is repeated,
The information communication terminal according to claim 2, wherein when the wake period is lengthened, the standby period is shortened.   The information communication terminal according to claim 3, wherein the information communication terminal detects that the period in which the frame cannot be received continues for a predetermined period based on the number of times the standby period in which the frame cannot be received is continuously repeated.   The information communication terminal according to claim 3, wherein the waiting period after shortening is calculated using predetermined default waiting period data and a random coefficient. Further comprising an information processing unit using the frame received by the communication unit in the standby period;
The information communication terminal according to claim 3, wherein the length of the waiting period is set according to a predetermined application program executed by the information processing unit.   The information communication terminal according to claim 3, wherein the standby period is lengthened and the wake period is shortened in order to reduce power consumption.   The information communication terminal according to claim 1, wherein the wireless network is an ad hoc communication network. A communication unit that receives a frame transmitted from another information communication terminal;
A power supply unit that supplies power to each circuit of the communication unit;
A clock circuit for supplying a clock for operating the circuit to each circuit of the communication unit,
In the state where the power is supplied, it is set to a reception waiting period for waiting for reception of the frame,
The reception waiting period includes a sleep period in which the clock circuit clock supply stops and a wake period in which the clock circuit clock supply is performed, and the sleep period and the wake period are alternately repeated,
A wireless communication apparatus mounted on an information communication terminal that changes a length of the wake period when a period during which the frame cannot be received continues for a predetermined period. A first information communication terminal and a second information communication terminal communicating with the first information communication terminal;
The first information communication terminal is
A communication unit for receiving a frame transmitted from the second information communication terminal;
A power supply unit that supplies power to each circuit of the communication unit;
A clock circuit for supplying a clock for operating the circuit to each circuit of the communication unit,
The communication unit is
In the state where the power is supplied, it is set to a reception waiting period for waiting for reception of the frame,
The reception standby period includes a sleep period in which the supply of the clock of the clock circuit is stopped and a wake period in which the clock of the clock circuit is supplied, and the sleep period and the wake period are alternately repeated,
A wireless communication network that changes a length of the wake period when a period during which the frame cannot be received continues for a predetermined period.

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