WO2004086682A1 - 無線通信システム - Google Patents
無線通信システム Download PDFInfo
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- WO2004086682A1 WO2004086682A1 PCT/JP2004/002898 JP2004002898W WO2004086682A1 WO 2004086682 A1 WO2004086682 A1 WO 2004086682A1 JP 2004002898 W JP2004002898 W JP 2004002898W WO 2004086682 A1 WO2004086682 A1 WO 2004086682A1
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- WIPO (PCT)
- Prior art keywords
- power saving
- layer frame
- header
- upper layer
- physical layer
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Classifications
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W52/00—Power management, e.g. TPC [Transmission Power Control], power saving or power classes
- H04W52/02—Power saving arrangements
- H04W52/0209—Power saving arrangements in terminal devices
- H04W52/0225—Power saving arrangements in terminal devices using monitoring of external events, e.g. the presence of a signal
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W52/00—Power management, e.g. TPC [Transmission Power Control], power saving or power classes
- H04W52/02—Power saving arrangements
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/06—Receivers
- H04B1/16—Circuits
- H04B1/1607—Supply circuits
- H04B1/1615—Switching on; Switching off, e.g. remotely
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02D—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE
- Y02D30/00—Reducing energy consumption in communication networks
- Y02D30/70—Reducing energy consumption in communication networks in wireless communication networks
Definitions
- the present invention relates to a wireless communication system, and in particular, to a wireless communication system that saves power in each terminal, the terminal, a processing method in the terminal, a program that causes a computer to execute the method, and a computer that records the program
- the present invention relates to a readable recording medium.
- wireless LANs local area networks
- MAC medium access control sublayer
- data link layer the physical layer and its immediate upper layer
- IEEE 80.2.11 The IEEE 80.2.11 standard by the working group of the 800 Standardization Committee of the Institute of Electrical and Electronics Engineers of Japan is known.
- the physical layer when using a medium called wireless, the physical layer is divided into two sub-layers: a PMD (physical medium dependent) sub-layer and a PLCP (physical layer comparison protocol) sub-layer. ing.
- PMD physical medium dependent
- PLCP physical layer comparison protocol
- the PMD sublayer multiple transmission schemes are defined according to the characteristics of the medium, such as frequency hopping scheme, direct spreading scheme, and infrared intensity modulation.
- the PLCP sub-layer is a protocol for transmitting information of the physical layer, and the PLC header holds information such as the modulation scheme, speed, and data length.
- the data link layer which is the upper layer of the physical layer, is composed of the MAC sublayer and LLC. (Logical link control) It is divided into sub-layers, and the IE EE 08.2.11 standard covers up to the MAC sub-layer, which is the next higher layer to the physical layer.
- the MAC sublayer controls access to the medium.
- the MAC header holds information such as the reserved time of the medium and the address of the device.
- the MAC frame by the MAC sublayer is transmitted after being encapsulated in the PLCP frame in the PLCP sublayer.
- the destination address and the packet duration in the upper layer header can be reduced by adding an error detection code by extending the frame configuration defined by the IEEE 802.11 standard. It is made available immediately.
- adopting such a means of extending the standard requires that both the transmitting side and the receiving side take measures to comply with the extension.
- the error detection code for the upper layer header is used. It is necessary to correct the error detection code added to the upper layer header at the wireless terminal after modifying the code so that it is generated and added to the upper layer header.
- an object of the present invention is to shift to a low power consumption state after acquiring necessary information without changing an existing standard in a wireless communication system.
- a wireless communication system is a wireless communication system including a plurality of devices, wherein a physical layer frame including an upper layer frame higher than a physical layer.
- the length of the upper layer frame is indicated in the header of the physical layer frame
- the destination of the upper layer frame is indicated in the header of the upper layer frame. If it is determined that the own device is not the destination at the time of receiving the frame header, the second device that is in the sleep state for a predetermined period based on the length of the upper layer frame extracted from the header of the physical layer frame is determined. Have it. As a result, there is an effect that the sleep state is provided in the second device without changing the existing standard in the first device.
- the terminal according to claim 2 of the present invention is a terminal that receives a physical layer frame including an upper layer frame higher than the physical layer, and operates in a power saving mode in which a power saving operation is performed as compared with a normal operation.
- a power saving operation time calculating means for calculating a power saving operation time based on a length of the upper layer frame extracted from a header of the physical layer frame, and a header of the upper layer frame.
- Address detection means for detecting a destination address at the time of reception and determining that the own terminal is not a destination, from the beginning of the body of the upper-layer frame to shift to the power saving mode, and the power saving mode.
- Means for measuring the power-saving operation time from the instruction to shift to and then instructing the cancellation of the power-saving mode when the power-saving operation time has elapsed This allows This has the effect of performing a power saving operation based on information extracted from the header of the physical layer frame in the existing standard.
- the power-saving operation time calculation means removes a header length of the upper layer frame from a length of the upper layer frame. A time that is equal to or longer than the first time corresponding to the portion described above and equal to or shorter than a second time obtained by adding the maximum frame interval to the first time is calculated as the power saving operation time. This brings about the effect that the power saving operation is performed from the transmission completion timing of the data frame to the other end to the transmission start timing of the next data frame.
- the power-saving operation time calculation means removes a header length of the upper layer frame from a length of the upper layer frame.
- the time obtained by adding the maximum frame interval to the time corresponding to the above portion is calculated as the power saving operation time. This brings about an effect that the power saving operation is performed until the transmission start timing of the data frame next to the data frame to another terminal.
- the terminal according to claim 5 of the present invention is the terminal according to claim 2, wherein when the information based on the physical layer frame does not satisfy a predetermined condition, regardless of the instruction from the address detection means, The apparatus further includes a suppression means for suppressing transition to the mode. This has the effect of suppressing the transition to power saving mode if it is not appropriate.
- the terminal according to claim 6 of the present invention is the terminal according to claim 5, wherein the suppression unit switches to the power saving mode when a predetermined error is detected in a preamble in the physical layer frame. It includes means to prevent migration. This brings about an effect that, when a predetermined error is detected in the preamble, the transition to the power saving mode is suppressed.
- the suppression unit switches to the power saving mode when a predetermined error is detected in a header of the physical layer frame. It includes means for restraining. As a result, when a predetermined error is detected in the header of the physical layer frame, there is an effect that the shift to the power saving mode is suppressed.
- the suppression unit detects that the header of the physical layer frame includes a value outside a predetermined range, This includes means for suppressing the transition to the power saving mode.
- the header of the physical layer frame includes a value out of the predetermined range, an effect of suppressing the shift to the power saving mode is provided.
- the terminal according to claim 9 of the present invention is the terminal according to claim 5, wherein the suppression unit is configured to determine that the power saving operation time calculated by the power saving operation time calculation unit is shorter than a predetermined time. Includes means for suppressing the transition to the power saving mode. As a result, there is an effect that the transition to the power saving mode is suppressed when the power saving operation time is shorter than the predetermined time.
- the processing method according to claim 10 of the present invention is characterized in that, in a terminal having a power saving mode in which power saving operation is performed as compared with a normal operation, a physical layer frame including an upper layer frame higher than the physical layer is A procedure for starting reception, a procedure for calculating a power saving operation time based on the length of the upper layer frame extracted from the header of the physical layer frame, and a destination when the header of the upper layer frame is received. If the terminal detects the address and determines that the terminal is not the destination, the procedure for instructing the transition to the power saving mode from the beginning of the body of the upper layer frame, and the procedure for instructing the transition to the power saving mode from the instruction for the transition to the power saving mode are described.
- the power saving mode When the power operation time is measured and the power saving operation time elapses, the power saving mode And a procedure for instructing cancellation. As a result, there is an effect that the power saving operation is performed based on the information extracted from the header of the physical layer frame in the existing standard.
- the processing method according to claim 10 when the information based on the physical layer frame does not satisfy a predetermined condition, the power saving is performed regardless of the instruction.
- the method further includes a procedure for suppressing the transition to the mode. As a result, when the transition to the power saving mode is not appropriate, it is possible to suppress the transition.
- the program according to claim 12 of the present invention is capable of receiving a physical layer frame including an upper layer frame higher than the physical layer in a terminal having a power saving mode for performing a power saving operation as compared with a normal operation.
- a power saving operation time based on the length of the upper layer frame extracted from the header of the physical layer frame, and a destination address when the header of the upper layer frame is received.
- the procedure for instructing cancellation of the power saving mode is executed.
- the power saving operation is performed based on the information extracted from the header of the physical layer frame in the existing standard.
- the program according to claim 12 of the present invention in the program according to claim 12, if the information based on the physical layer frame does not satisfy a predetermined condition, the program is saved regardless of the instruction. This causes the terminal to further execute a procedure to suppress the transition to the power mode. This has the effect of suppressing the transition to the power saving mode if it is not appropriate.
- the computer-readable recording medium according to claim 14 of the present invention includes a terminal having a power saving mode in which power saving operation is performed as compared with a normal operation, including an upper layer frame higher than the physical layer.
- the computer-readable recording medium according to claim 15 of the present invention is the computer-readable recording medium according to claim 14, wherein the information based on the physical layer frame does not satisfy a predetermined condition.
- This is a program for causing a terminal to further execute a procedure for suppressing the transition to the power saving mode regardless of the above instruction. This has the effect of suppressing the transition to the power saving mode when it is not appropriate.
- FIG. 1 is a diagram illustrating an example of an overall configuration of a wireless communication system according to an embodiment of the present invention.
- FIG. 2 is a diagram illustrating a configuration example of the wireless terminal 100 according to the embodiment of the present invention.
- FIG. 3 is a diagram illustrating a configuration example of the power supply control unit 400 according to the embodiment of the present invention.
- FIG. 4 is a diagram showing a configuration of the MAC frame 820 in the IEEE802.11 standard.
- FIG. 5 is a diagram showing a configuration of the PLCP frame 830 in the IEEE802.1b standard.
- FIG. 6 is a diagram illustrating the relationship between the value of the signal 836 and the transmission speed 83361 in the IEEE802.11.1b standard.
- FIG. 7 is a diagram showing the contents of the value of the service 837 in the IEEE802.11b standard.
- FIG. 8 is a diagram showing an example of application of the sleep length calculation unit 410 to the IEEE 802.11.1b standard in the embodiment of the present invention.
- FIG. 9 is a diagram showing a configuration of a PLCP frame 840 according to the IEEE 802.11a standard.
- FIG. 10 is a diagram showing the contents of the value of the data rate 844 in the IEEE802.11.1a standard.
- FIG. 11 is a diagram illustrating an example in which the sleep length calculation unit 410 according to the embodiment of the present invention is applied to the IEEE 800.2.11a standard.
- FIGS. 12A and 12B are diagrams showing a relationship between a transmission sequence in a wireless communication system and a transmission / reception operation in a wireless terminal.
- FIG. 13 is a diagram showing an example of the end timing of the sleep operation.
- FIG. 14 is a diagram showing timings at which a data frame cannot be normally received in the example of FIG.
- FIG. 15 is a diagram illustrating another example of the end timing of the sleep operation.
- FIG. 16 is a diagram illustrating a processing procedure of the wireless terminal 100 according to the embodiment of the present invention. BEST MODE FOR CARRYING OUT THE INVENTION
- FIG. 1 is a diagram illustrating an example of an overall configuration of a wireless communication system according to an embodiment of the present invention.
- an access point 200 is connected to the network 300 by wire, and the access point 200 and a plurality of wireless terminals 100 are wirelessly connected.
- the access point 2000 and the wireless terminal 100 form a wireless LAN which is a separate network from the network 300.
- a communication mode in which a network is formed using access points in this way is called an infrastructure mode.
- each wireless terminal 100 communicates with a wireless terminal 100 belonging to another wireless LAN from one access point 200 via another access point 200 connected to the network 300. Can also be performed.
- FIG. 2 is a diagram illustrating a configuration example of the wireless terminal 100 according to the embodiment of the present invention.
- the wireless terminal 100 connects a wireless communication unit 110, a modem unit 120, a MAC processing unit 130, a processor 140, and a memory 150 by a bus 190.
- the configuration is as follows. Further, an interface section 160 is connected to the memory 150.
- the wireless terminal 100 has a power supply unit 180, and power is supplied from the power supply unit 180 to each unit in the wireless terminal 100 by a power line (not shown). .
- the wireless communication unit 110 is for performing wireless communication with the outside of the wireless terminal, and includes a receiving unit 111 for receiving a wireless signal, a transmitting unit 112 for transmitting a wireless signal, It comprises a frequency synthesizer 113 for generating a frequency signal for transmitting and receiving a radio signal, and an antenna switch 114 for switching an antenna between the receiving unit 111 and the transmitting unit 112.
- a frequency synthesizer 113 for example, a PLL circuit (phase locked loop) is used.
- An antenna 105 is connected to the frequency synthesizer 113.
- the modulation and demodulation unit 120 performs conversion between a transmission / reception signal in the wireless communication unit 110 and a digital signal inside the wireless terminal, and demodulates a signal from the reception unit 111.
- the modulation method in wireless LAN is divided into primary modulation and secondary modulation.
- Primary modulation includes ASK (amplitude modulation), FSK (frequency modulation), PSK (phase modulation), QAM (quadrature amplitude modulation), and CCK (complementary code modulation).
- secondary modulation include a frequency hobbing method (FHSS) using spread spectrum technology, a direct spreading method (DSSS), and an orthogonal frequency division multiplexing method (OFDM).
- FHSS frequency hobbing method
- DSSS direct spreading method
- OFDM orthogonal frequency division multiplexing method
- the MAC processing unit 130 includes a MAC control unit 131 that performs processing in the MAC sublayer, a reception data buffer 133 that holds a signal from the demodulation unit 121, and a signal to the modulation unit 122. And a transmission data buffer 138 holding the same.
- the MAC processing unit 130 includes a preamble detection unit 132 that detects a preamble of the signal from the demodulation unit 121 and a PLCP header processing unit 133 that processes a PLCP header. And a MAC header processing unit 134 that processes the MAC header, and a power control unit 400 that controls the power supply unit 180 based on these outputs. ! ⁇
- the control unit 13 1 and the power supply control unit 400 are connected to the path 190.
- the processor 140 controls the entire wireless terminal 100.
- the memory 150 holds a work area for the processor 140 to perform processing.
- the interface unit 160 is for connecting the wireless terminal 100 to another computer or portable device. These other devices may be physically connected to the outside of the wireless terminal 100, or may be in a connection form in which the wireless terminal 100 is built in another device.
- the power supply unit 180 has a power saving mode for performing power saving operation and a normal mode for performing normal operation when supplying power to each unit. Operating in this power saving mode is commonly referred to as “sleep”. Control such as start and stop of the sleep and suppression of the sleep that does not perform the sleep is realized by the power supply control unit 400.
- FIG. 3 is a diagram illustrating a configuration example of the power supply control unit 400 according to the embodiment of the present invention.
- the power supply control section 400 includes a sleep length calculation section 410 for calculating a sleep length, an address detection section 420 for detecting a destination address of a frame, and a timer 4 for measuring a sleep length. 30 and a sleep suppression determination unit 4440 for suppressing sleep.
- the sleep length calculation unit 410 calculates the sleep length based on the PLCP header of the PLCP frame given from the PLCP header processing unit 133, and the sleep length is calculated by the timer 43 Set to 0.
- the address detection unit 420 detects a destination address based on the MAC header of the MAC frame provided from the MAC header processing unit 134, and determines whether the destination address is an address of another terminal. For example, the power supply unit 180 is instructed to start sleep ( at the same time as the sleep start instruction), the address detection unit 420 counts the sleep length set in the timer 430. Thus, the timer 430 starts counting the sleep length set by the sleep length calculation unit 41 ⁇ , and when the sleep length has elapsed, the timer 430 switches to the power supply unit 180. Instruct sleep stop.
- the sleep suppression determination section 440 suppresses sleep so that the power supply section 180 does not enter the power saving mode, and uses the information on data error detection provided from the preamp detection section 132.
- a rise time determination unit 443 that determines the relationship between each part of the wireless terminal 100 and the rise time based on the sleep length given by the wireless terminal 100.
- the preamble judging unit 441 sends a signal to the power supply unit 180 when a data error equal to or greater than a certain threshold is detected based on the data error detection information given from the preamble detecting unit 132.
- a certain threshold is detected based on the data error detection information given from the preamble detecting unit 132.
- control is performed so as to maintain the normal mode so as not to cause reception leakage due to the power saving mode being set under an incorrect condition.
- the PLCP determination unit 442 detects an error in the PLCP header based on information from the PLCP header processing unit 133, and sleeps to the power supply unit 180 if an error is detected. Deter. For example, if IEEE802. 1 lb, error detection is performed by HEC (Header Error Control). In the case of IEEE802.11a, error detection is performed by parity after the convolutional code is solved.
- HEC Header Error Control
- the 0? Determination unit 442 checks whether the value of each field in the PLCP header is a logically incorrect value. That is, in each field Each has a defined value, and it is not logical to indicate an undefined value. Therefore, if there is a field indicating such an undefined value, sleep is suppressed by presuming that some error has occurred.
- the rise time determination unit 443 determines the relationship between the rise time of each unit of the wireless terminal 100 based on the sleep length given from the sleep length calculation unit 410 and the sleep length is determined by the wireless terminal 10 If the rise time is shorter than the rise time of each part of 0, sleep is suppressed for the power supply section 180. For example, assuming that the PLL circuit in the frequency synthesizer 113 requires a rise time of about 100 microseconds to operate stably, the sleep effect will be effective if the sleep length is about the same. Can not be obtained. With a margin, 150 microseconds is equivalent to about 207 bytes at 11 Mbit / s, so if there is no longer byte length, it will be enough to rise from sleep. May be gone. Therefore, in this case, sleep can be controlled only when the MAC frame has a capacity of 2337 bytes or more, which is the sum of the MAC header capacity and 30 bytes.
- FIG. 4 is a diagram illustrating a configuration of a MAC frame 820 in the IEEE 80.2.11 standard.
- the MAC frame 820 which transmits information in the MAC sublayer, includes a MAC header 821, a frame body 810, and an FCS (frame check sequence) 829.
- the MAC header 8 21 includes a frame control 8 22, a period 8 23, an address 1 (8 24), an address 2 (8 2 5), and an address 3 (8 2 6). , A sequence control register 827, and an address 4 (828).
- the frame control 822 is a builder indicating frame control information, and includes information on a frame type and a communication mode.
- the period 8 23 is a field indicating the reservation time until the frame transmission is completed.
- the sequence control 827 is a field indicating a fragment number and a sequence number when the fragment is divided.
- Addresses 1 to 4 are fields indicating the transmission address and destination address of the frame. Which address each of these four end addresses means depends on the communication mode in the frame control 822. For example, in the case of communication from the access point 200 in FIG. 1 to the wireless terminal 100, address 1 (8 24) indicates the destination address, and address 3 (8 2 6) indicates the outgoing address. Show. As shown in Fig. 4, the capacity of each field in the MAC header 821, frame control 822, period 823, and sequence control 827 are 2 bytes each, Addresses 1 to 4 (824 to 826 and 828) each have 6 bytes. Therefore, the MAC header 8221 as a whole has a total of 30 bytes.
- the frame body 8100 corresponds to the payload of the MAC frame 820, and is used for transmitting data in the MAC sublayer.
- This frame body 810 has a capacity of at most 2 312 feet.
- FCS 829 is a field for detecting an error in the MAC frame 820, and is set to the number of remainders 1 obtained by remainder calculation of the generator polynomial. This FCS 829 has 4 bytes. Accordingly, the MAC frame 8200 as a whole has a maximum capacity of 2346 bytes.
- FIG. 5 is a diagram showing a configuration of a PLCP frame 830 according to the IEEE 80.2.11b standard.
- PLCP frame 830 in PLCP sublayer It has a preamble 831 and a PLCP header 832, and has a MAC frame 820 as a payload.
- the preamble 831 is a signal for synchronization, and is composed of a synchronization bit 834 and a delimiter 835.
- the IEEE 802.1 lib standard has a long format for maintaining compatibility with the direct spreading method of the IEEE 80.2.11 standard and a short format for high-speed operation.
- the synchronization bit 834 is 128 bits
- the synchronization bit 834 is 56 bits.
- the delimiter 835 is 16 bits. Therefore, the preamble as a whole has 144 or 72 bits.
- the PLC header 832 includes a signal 836, a service 837, a length 838, and a CRC (Cyclic Redundancy Check) 839.
- Signal 833 is a field indicating the transmission rate.
- the service 837 is a field indicating a modulation method and the like.
- the length 838 is a field indicating the length of the MAC frame 820 in microseconds.
- CRC 839 is a field for performing error detection of the PLC header 832.
- the PLC header 832 In the PLC header 832, the signal 836 and the service 837 each have 8 bits, and the length 838 and the CRC 839 each have 16 bits. Therefore, the PLC header 832 as a whole has 48 bits.
- the transfer time of the PLCP frame 8330 is calculated, in the long format, the preamble 831 and the PLCP header 832 are both transferred at 1 Mbit second.
- the preamplifier 831 is transmitted at 1 Mbit / sec and the PLCP header 832 is transmitted at 2 Mbit / sec.
- the transfer time of the MAC frame 820 depends on the capacity of the frame body 810 and the transmission rate specified in the signal 836.
- FIG. 6 is a diagram showing the relationship between the value of the signal 836 and the transmission speed 8361 in the IEEE 802.11b standard.
- the signal 836 determines the transmission rate of the MAC frame 820. Therefore, by referring to the signal 836 of the PLC header 832 in the IEEE802.lib standard, the transmission rate 8361 can be obtained.
- "0x ⁇ " means 16 hexadecimal notation
- "0b ⁇ " means binary notation.
- the transmission rate is 1 Mbit / s, if it is ⁇ 1 4 '', the transmission rate is 2 Mbits / s, ⁇ 37 J Indicates a transmission rate of 5.5 Mbits / s, and “6E” indicates a transmission rate of 11 Mbits / s.
- Signal 8336 if normal, will have no other value than these four values. Therefore, when there are other undefined values, it can be determined that signal 836 contains an error. This judgment is made by the PLCP judging section 442 (FIG. 3).
- FIG. 7 is a diagram showing the contents of the value of the service 837 in the IEEE802.11b standard.
- the service 837 has an 8-bit field, and the modulation method 8371 is specified in the fourth most significant bit, and the length extension 8372 is defined in the least significant bit.
- Modulation method 8 3 7 1 means “C CK” when “0”, and “1” when Means PBCC (Packet Binary Convolutional Code).
- PBCC Packet Binary Convolutional Code
- the specification of these modulation methods is effective when the transmission speed is 5.5 Mbits Z second and 11 Mbits / second extended by the IEEE 80 2. lib standard.
- DB PSK differential binary PSK
- DQ PSK differential 4-level PSK
- the length extension 8 3 7 2 captures the length 8 3 8 and, when the transmission rate is 11 Mbit / s, the length 8 3 8 and M in units of time (microseconds). It is used to convert between the number of bits of the AC frame 820 and the number of bits. The specific calculation method will be described later.
- FIG. 8 is a diagram illustrating an example of application of the sleep length calculation unit 410 to the IEEE 802.11.1b standard in the embodiment of the present invention.
- the sleep length calculation unit 410 includes a frame length calculation unit 411 that calculates the capacity of the MAC frame 820, a subtractor 412 that subtracts the capacity of the MAC header 821, and a transmission speed 8000. And a divider 4 13 for performing division by 3 6 1.
- the length 8 3 8 of the €? Header 8 3 2 is the time conversion length in units of the microphone mouth seconds.
- the length 838 is converted into bytes, but the length of the MAC header 821 may be converted into time.
- the frame length calculation unit 4 1 1 uses the transmission speed 8 3 6 1 of the signal 8 3 6, the modulation method 8 3 7 1 of the service 8 3 7 and the length extension 8 3 7 2. Convert unit length 8 3 8 to byte units as follows You.
- modulation method 837 1 CCK
- Frame length [bytes] length 8 3 8 [microseconds] X 5.5 / 8
- Frame length [bytes] (length 8 3 8 [microseconds] XI 1/8)
- One-length extension 8 3 7 2 (decimal point truncation)
- Transmission speed 8 3 6 1 5.5 bits per second Modulation method 8 3 7 1-For PBCC;
- Frame length [bytes] (length 8 3 8 [microphone mouth seconds] X 5-5 8) 1 1
- Frame length [bytes] (length 8 3 8 [microphone seconds] XI 1/8) one-length extension 8 3 7 2 (decimal point truncation)
- the frame length in pets thus obtained Subtract 30 bytes by subtractor 4 1 2 from.
- the body length of the body part that is, the frame body 810 and the FCS 829) excluding the MAC header 821 from the MAC frame 820 is obtained in byte units. If the body length is divided by the divider 4 13 at the transmission speed 836 1 of the signal 836, the time required for transferring the body portion is calculated.
- transmission rate 836 1 11 Mbit / s
- modulation method 837 1 In the case of CCK, if the length 8 3 8 is 744 and the length extension 8 3 7 2 is 0, the frame length is
- This body length may be used as the sleep length, but the maximum frame interval (DIFS) can be added to this body length as described later. For example, if the maximum interval between frames is 128 microseconds, the sleep length is
- FIG. 9 is a diagram showing a configuration of a PLCP frame 840 in the IEEE802.11a standard.
- the PLCP frame S40 similar to the PLCP frame 830, transmits information in the PLCP sublayer, and includes a preamble 841, a PLCP header 842, and a MAC as a payload. It has a frame 820.
- the frequency of the 5 GHz band which is different from the frequency 2.4 GHz band of the IEEE 80.2.11 standard is used. There is no compatibility, and a different frame format is used.
- the preamble 841 is a signal for synchronizing, and has a length of 12 symbols.
- the symbol is a unit of modulation used in the OFDM scheme in the IEEE802.11a standard.
- signals are transmitted in parallel using multiple orthogonal subcarriers simultaneously, and some subcarriers could not be received due to interfering waves or interference by using error correction codes in combination.
- the data can be reproduced at any time.
- the PLCP header 842 has a data rate 844, a length 8464, and a 849, tail 848, and service 849.
- Data rate 844 is a field representing the transmission rate.
- the length 846 is a field representing the length of the MAC frame 820 in bytes.
- Parity 847 is a code used for error detection.
- the tail 844 is a field representing the tail of the signal 843 starting from the data rate 844.
- the data rate 844 is 4 bits, length 84
- 6 is 12 bits, no.
- the ity 847 has one bit and the tail 848 has six bits. Also, between the data rate 844 and the length 846, there are unused bits 845 S1 bits. Therefore, 24 bits are used as the signal 843. All 6 bits of the tail 8 4 8 are set to 0.
- Service 849 has a 16-bit field, with the upper 7 bits used to synchronize with the descrambler on the receiver side and the lower 9 bits reserved for future use. ing. All 0s are set in these 16-bit fields.
- FIG. 10 is a diagram showing the contents of the value of the data rate 844 in the IEEE802.11a standard. For each value of the data rate 8444, a modulation method 8441, a coding rate 84444, and a transmission rate 84443 are defined. Therefore, by referring to the data rate 844 of the PLC header 842 in the IEEE802.11a standard, the transmission rate 8
- FIG. 11 is a diagram illustrating an example in which the sleep length calculation unit 410 according to the embodiment of the present invention is applied to the IEEE 802.11a standard.
- the sleep length calculation unit 4 10 includes a subtracter 4 15 for subtracting the capacity of the MAC header 8 21 from the capacity of the MAC frame 8 20, and a divider 4 16 for performing division by the transmission speed 8 4 4 3.
- the length 846 of the PLCP header 842 is a capacity-converted length in bytes. Therefore, unlike the case of the IEEE802.11b standard, the body length can be obtained without converting from time units to capacity units. That is, the body length is obtained by subtracting 30 bits of the MAC header 821 from the length 846 by the subtractor 412. Then, when the body length is divided by the transmission rate S444 of the data rate 844 by the divider 416, the time required for transferring the body portion is calculated.
- This body length may be used as the sleep length, and the maximum frame length may be added to this body length.
- the point that the interval can be added is the same as in the case of the IEEE 80.2.11b standard described above.
- FIGS. 12A and 12B are diagrams showing a relationship between a transmission sequence in a wireless communication system and a transmission / reception operation in a wireless terminal.
- FIG. 12A shows a transmission sequence in communication between access point A and terminals B and C
- FIG. 12B shows a transmission / reception operation of terminal C corresponding to the transmission sequence.
- access point A transmits data frame 13 to terminal B.
- the terminal C enters the receiving operation 331 and starts receiving the PLCP frame 830.However, when the MAC header 821 is received, the destination is determined. Move to operation 3 3 2. For this data frame 13, terminal B sends ACK frame 24 to access point A.
- the terminal C enters the receiving operation 351, but the destination is also the access point when the MAC header 8 21 is received.
- the operation shifts to the sleep operation 352.
- the body length is used as the sleep length, and the period from immediately after the reception of the MAC header 82 1 to the completion of the transmission of the FCS 8 29 is completed. It operates in sleep mode.
- the end timing of the sleep operation is not necessarily limited to this, and a longer time can be used as the sleep length.
- FIG. 13 is a diagram showing an example of the end timing of the sleep operation.
- the IEEE 802.11 standard specifies a frame interval (IFS) to determine whether the medium to be accessed is in an idle state, and a signal is transmitted over the medium for a specified time or longer. If not detected, It is determined to be idle.
- a plurality of frame intervals are defined as this frame interval, and a shortest frame interval (SIFS) is defined as a timing at which a device that has normally received a data frame transmits an ACK frame.
- the maximum frame interval (DIFS) is defined as the timing at which a terminal transmits a data frame.
- access point A transmits data frame 16 to terminal B.
- the terminal C After the terminal C enters the receiving operation 361, when receiving the MAC header 821, the terminal C shifts to the sleeping operation 362.
- the sleep length is obtained by adding the shortest frame interval and the ACK bucket length to the body length. Even if the sleep length is set in this way, if the next data frame 48 is transmitted in accordance with the rules as shown in Fig. 13, terminal C returns to receiving operation 38 1 again. There is no problem because you can enter sleep mode after entering. However, if the terminal B cannot receive the data frame 16 normally, the terminal B does not transmit the ACK frame 27, so the following inconvenience occurs.
- FIG. 14 is a diagram showing timings at which a data frame cannot be normally received in the example of FIG. Normally, terminal B normally receives data frame 16 transmitted by access point A, and terminal B transmits ACK frame 27 to access point A in response. As a result, terminals other than the terminal B cannot transmit the data frame at the timing overlapping the ACK frame 27.
- the terminal B cannot receive the data frame 16 normally, the terminal B does not transmit the ACK frame 27.
- Other terminals can transmit data frames.
- Figure 14 In terminal D data frame 48 is transmitted.
- the terminal C since the terminal C is in the sleep state until the end timing of the original ACK frame 27, the terminal C cannot receive the data frame 48 transmitted from the terminal D, and a non-reception period 37 occurs. Therefore, even if an attempt is made to receive the data frame 48 by the subsequent receiving operation 381, it cannot be normally received.
- FIG. 15 is a diagram illustrating another example of the end timing of the sleep operation.
- the sleep length of the sleep operation 365 when the access point A transmits the data frame 16 is the body length plus the maximum frame interval.
- the maximum frame interval from the completion of transmission of data frame 16 is assumed.
- the terminal C can enter the receiving operation 381 of the data frame 48.
- the body length may be used as it is as the sleep length, but it is more preferable that the sleep length be longer than the body length plus the maximum frame interval.
- a non-reception period 37 may occur. However, even when such a non-reception period 37 occurs, if a frame addressed to the own terminal cannot be received, the frame is retransmitted, so the efficiency is reduced but the processing content is reduced. There is no inconsistency.
- wireless terminal 100 Next, the operation of wireless terminal 100 according to the embodiment of the present invention will be described with reference to the drawings.
- FIG. 16 is a diagram illustrating a processing procedure of the wireless terminal 100 according to the embodiment of the present invention.
- Wireless terminal 100 PLCP frame 8 3 0 (8 4 0)
- the preamble checker 1332 detects an error in the preamble 831 (841).
- the preamble determination unit 441 determines that a data error equal to or greater than a certain threshold is detected (step S 902), the power supply may be degraded because the quality of the transmission path may be degraded.
- the normal reception operation is performed for the section 180 with the sleep suppressed (step S910).
- step S902 If it is determined in step S902 that no data error equal to or greater than the threshold is detected, then the PLC header processing unit 133 detects the error of the PLC header 832 (842). When the PLCP determination section 442 determines that a predetermined error has been detected (step S903), the information in the PLCP header 832 (842) may have an error. The sleep is suppressed for the power supply unit 180 to perform a normal reception operation (step S910).
- the PLCP determination unit 442 further specifies the length 846 (838) in the PLCP header 842 (832). It is determined whether it is a value. That is, since the maximum length of the MAC frame 820 is 2 346 bytes, if the length 846 exceeds that, the information itself is erroneous. Therefore, if the PLCP determination unit 442 determines that the value includes such an out-of-spec value (step S904), the information in the PLCP header 842 (832) may have an error. For this reason, sleep is suppressed for the power supply unit 180 to perform a normal reception operation (step S910).
- the PLCP determination section 442 further transmits the data in the PLCP header 832 (842). Speed, or signal 8 3 6 It is determined whether (data rate 844) is a defined value. Then, when the PLCP determination unit 442 determines that the value includes an undefined value (step S905), the information in the PLCP header 832 (842) may have an error. Then, the sleep is suppressed for the power supply unit 180 to perform a normal reception operation (step S910).
- step S906 the sleep length is calculated by the sleep length calculation unit 410 (step S906).
- the sleep length is set in timer 430.
- the sleep length calculated in step S906 is compared with the rise time of each unit in the wireless terminal 100 by the rise time determination unit 443. If the sleep length is not determined to be longer than these rise times (step S907), the sleep effect is not obtained, so that sleep is suppressed for the power supply unit 180 and normal operation is performed. (Step S910).
- step S907 If it is determined in step S907 that the sleep length is longer than the rise time, the end address detector 420 checks the destination address. If it is determined that the destination address is not the address of its own terminal (step S 908), it is not necessary to receive any more, and the sleep operation is instructed by instructing the power supply unit 180 to start sleep. The process proceeds to (Step S909). At this time, the timer 430 also starts measuring the sleep length. As a result, the timer 430 instructs the power supply unit 180 to stop sleep after the sleep length has elapsed. On the other hand, if the destination address is the address of the terminal itself (step S908), a normal reception operation is performed (step S910).
- the start of the PLCP frame 830 (840)
- the preamble 831 (841)
- the MAC header 821 it is determined whether or not to sleep. Therefore, until the reception of the MAC header 821 is completed, the reception state is the normal operation.
- the sleep operation of 1 6 8 4 microphone mouth seconds will be performed. More specifically, the sleep length depends on the length of the frame body 810, and the maximum frame interval can be further added as described above.
- power consumption in the receiving state is assumed to be about 500 mW to 1 W.
- the power consumption in the sleep state is assumed to be about 100 mW to 300 mW.
- the improvement rate of the power consumption in the above-described short format example is as follows.
- the sleep length calculation unit 4100 of the power supply control unit 400 adds the contents of the PLCP header 832 (842) to Calculate the sleep length based on the MAC address and detect the destination address from the contents of the MAC header 821 in the address detection unit 420. Can be transferred to
- the PLCP header 832 (842) includes CRC 839 (parity 847) in the existing standard, so that the sleep length can be calculated safely.
- the sleep suppression determination unit 440 will stop. Suppress transition to the leap state. Thereby, the sleep operation can be performed more safely.
- the embodiment of the present invention is an example for embodying the present invention, and has a correspondence relationship with the invention specifying matters in the claims as described below, but is not limited thereto. Various modifications can be made without departing from the spirit of the present invention.
- the upper layer frame corresponds to, for example, a MAC frame 82
- the physical layer frame corresponds to, for example, a PLCP frame 830 or 840
- the first device is, for example, access point 2.
- the second device corresponds to the wireless terminal 100, for example.
- the terminal corresponds to, for example, the wireless terminal 100
- the upper layer frame corresponds to, for example, the MAC frame 820
- the physical layer frame corresponds to, for example, the PLCP frame 830 or 840.
- the power saving operation time calculation means corresponds to, for example, the sleep length calculation section 410
- the address detection means corresponds to, for example, the address detection section 420
- the means for instructing the release of the power saving mode is, for example, a timer. Corresponds to 4 3 0.
- the first time corresponds to, for example, the time required to transfer the frame body 810 and the FCS 8229
- the second time Corresponds to, for example, the first time plus the maximum frame interval (DIFS).
- the inhibiting means corresponds to, for example, the sleep inhibition determining unit 440.
- means for suppressing the transition to the power saving mode when a predetermined error is detected in the preamble in the physical layer frame corresponds to, for example, the preamble determination unit 441.
- means for suppressing the transition to the power saving mode when a predetermined error is detected in the header of the physical layer frame corresponds to, for example, the PLCP determination unit 442.
- the means for suppressing the transition to the power saving mode corresponds to, for example, the PLCP determination unit 442.
- the means for suppressing the transition to the power-saving mode is, for example, a rise time determination unit 4 4 3 Corresponding to
- a terminal corresponds to, for example, a wireless terminal 100
- an upper layer frame corresponds to, for example, a MAC frame 820
- a physical layer frame corresponds to, for example, a MAC frame 820.
- the procedure for starting to receive a physical layer frame corresponding to the PLCP frame 830 or 840 and including an upper layer frame higher than the physical layer corresponds to, for example, step S910, and a physical layer frame.
- the procedure for calculating the power saving operation time based on the length of the upper layer frame extracted from the header corresponds to, for example, step S906, in which the destination address is determined when the header of the upper layer frame is received.
- step S908 The procedure for instructing a transition to the power saving mode from the top of the body of the upper layer frame when detecting and determining that the own terminal is not the destination corresponds to, for example, step S908, and The procedure for measuring the power saving operation time from the instruction to shift to the power saving mode and instructing the cancellation of the power saving mode when the power saving operation time elapses corresponds to, for example, step S909.
- claim 13 and claim 15 if the information based on the physical layer frame does not satisfy the predetermined condition, the procedure for suppressing the transition to the power saving mode regardless of the instruction is For example, it corresponds to steps S902, S903, S904, S905 and S907.
- the sleep length is calculated by the sleep length calculation unit 410 in the power supply control unit 400, but the calculation of the sleep length is performed by the processor 140. It may be executed.
- processing procedure described in the embodiment of the present invention may be regarded as a method having a series of these procedures, and a program for causing a computer to execute the series of procedures and a program for storing the program are stored. It may be considered as a recording medium.
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Abstract
Description
Claims
Priority Applications (1)
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US10/550,234 US7356316B2 (en) | 2003-03-26 | 2004-03-05 | Wireless communication system |
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JP2003086160A JP3826893B2 (ja) | 2003-03-26 | 2003-03-26 | 無線通信システム |
JP2003-086160 | 2003-03-26 |
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WO2004086682A1 true WO2004086682A1 (ja) | 2004-10-07 |
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PCT/JP2004/002898 WO2004086682A1 (ja) | 2003-03-26 | 2004-03-05 | 無線通信システム |
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US (1) | US7356316B2 (ja) |
JP (1) | JP3826893B2 (ja) |
KR (1) | KR20050118199A (ja) |
CN (1) | CN100508483C (ja) |
WO (1) | WO2004086682A1 (ja) |
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Also Published As
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CN1795644A (zh) | 2006-06-28 |
KR20050118199A (ko) | 2005-12-15 |
US7356316B2 (en) | 2008-04-08 |
JP2004297394A (ja) | 2004-10-21 |
JP3826893B2 (ja) | 2006-09-27 |
US20060072614A1 (en) | 2006-04-06 |
CN100508483C (zh) | 2009-07-01 |
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