WO2007011469A1 - Method and apparatus for reducing power consumption within a wireless receiver - Google Patents
Method and apparatus for reducing power consumption within a wireless receiver Download PDFInfo
- Publication number
- WO2007011469A1 WO2007011469A1 PCT/US2006/021972 US2006021972W WO2007011469A1 WO 2007011469 A1 WO2007011469 A1 WO 2007011469A1 US 2006021972 W US2006021972 W US 2006021972W WO 2007011469 A1 WO2007011469 A1 WO 2007011469A1
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- WO
- WIPO (PCT)
- Prior art keywords
- chips
- symbol
- chip
- receiver
- received
- Prior art date
Links
Classifications
-
- 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
- H04B1/69—Spread spectrum techniques
- H04B1/707—Spread spectrum techniques using direct sequence modulation
- H04B1/7073—Synchronisation aspects
- H04B1/7075—Synchronisation aspects with code phase acquisition
- H04B1/70751—Synchronisation aspects with code phase acquisition using partial detection
- H04B1/70752—Partial correlation
-
- 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
-
- 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
- H04W52/0229—Power saving arrangements in terminal devices using monitoring of external events, e.g. the presence of a signal where the received signal is a wanted signal
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B2201/00—Indexing scheme relating to details of transmission systems not covered by a single group of H04B3/00 - H04B13/00
- H04B2201/69—Orthogonal indexing scheme relating to spread spectrum techniques in general
- H04B2201/707—Orthogonal indexing scheme relating to spread spectrum techniques in general relating to direct sequence modulation
- H04B2201/70707—Efficiency-related aspects
-
- 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
- H04W52/0245—Power saving arrangements in terminal devices using monitoring of external events, e.g. the presence of a signal according to signal strength
-
- 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
- H04W52/0261—Power saving arrangements in terminal devices managing power supply demand, e.g. depending on battery level
- H04W52/0274—Power saving arrangements in terminal devices managing power supply demand, e.g. depending on battery level by switching on or off the equipment or parts thereof
- H04W52/028—Power saving arrangements in terminal devices managing power supply demand, e.g. depending on battery level by switching on or off the equipment or parts thereof switching on or off only a part of the equipment circuit blocks
- H04W52/0283—Power saving arrangements in terminal devices managing power supply demand, e.g. depending on battery level by switching on or off the equipment or parts thereof switching on or off only a part of the equipment circuit blocks with sequential power up or power down of successive circuit blocks, e.g. switching on the local oscillator before RF or mixer stages
-
- 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 generally to wireless receivers and in particular, to a method and apparatus for reducing power consumption within a wireless receiver.
- FIG. 1 is a block diagram of a radio receiver.
- FIG. 2 is a flow chart showing the operation of the radio receiver of FIG. 1.
- partial chip sequence correlation to reduce the average power consumption of a direct sequence spread spectrum (DSSS) wireless transceiver.
- the receiver will attempt to correlate, or de-spread, less than all chips that constitute a symbol.
- a partial correlation may be performed on M chips, where M may be much less than N, the number of chips that represent a whole symbol.
- the M chips are the first M chips in the symbol.
- high power consumption circuits such as the receiver front end, may be set to a low-power state for the remainder of the symbol, and then returned to normal operating power prior to the beginning of the next symbol.
- the low-power state may be achieved by a reduction of supply current, voltage, or clock frequency; by switching the circuits off completely, or by a combination of these or other techniques. This can significantly reduce power consumption of the receiver.
- the present invention encompasses a method for reducing power consumption within a wireless receiver.
- the method comprises the steps of receiving M chips from a chip stream, wherein symbols comprise N chips and M ⁇ N, associating the M chips from the chip stream with a symbol, and placing at least one component within the receiver in a low-power state for a predetermined period of time.
- the present invention additionally encompasses a method for reducing power consumption within a wireless receiver.
- the method comprises the steps of receiving M chips from a chip stream, wherein symbols comprise N chips and M ⁇ N, determining a received signal characteristic, determining if the received signal characteristic satisfies a criterion, and associating the M chips from the chip stream with a symbol if the criterion is satisfied.
- At least one component within the receiver is placed in a low-power state if the criterion is satisfied until a beginning of a next symbol period.
- the present invention encompasses an apparatus comprising a correlator receiving M chips from a chip stream, wherein symbols comprise N chips and M ⁇ N, the correlator determining correlation values of the M chips with possible symbols.
- the apparatus additionally encompasses decision circuitry associating the M chips from the chip stream with a symbol based on the correlation values, outputting the symbol, and placing at least one component within the receiver in a low-power state for a predetermined period of time.
- FIG. 1 is a block diagram of an exemplary radio receiver 100.
- receiver 100 comprises antenna 102, RF processing circuitry 103, analog-to-digital (ATD) converter 104, and demodulator 105.
- signal 101 is received by antenna 102 and passed to RF processing circuitry 103, which may include amplifier 107, filter 109, and frequency-translation circuitry 111 to downconvert the RF signal to a baseband signal.
- A/D converter 104 receives the baseband signal and outputs an appropriately converted digital signal representing a chip stream.
- the digital signal output from A/D converter 104 may simply be an actual chip stream, or if multiple samples per chip are obtained, the digital signal may comprise a plurality of samples representing each chip. For example, if two samples were taken by A/D converter per chip period, then A/D converter 104 will output a digital stream where each chip is represented by two values.
- each symbol is represented by a plurality of chip values.
- a symbol may convey one or more bits of information, in which case it is commonly referred to as a data symbol.
- the symbol may additionally provide a reference phase or amplitude used by a receiver to assist signal reception, in which case it is referred to as a pilot or training symbol.
- a transceiver utilizing the 2.4 GHz IEEE 802.15.4 system protocol conveys 4 information bits per data symbol, with each of the 16 possible data symbols represented by a sequence of 32 chips. So, for example, the data symbol 0 will be represented by the chip stream 11011001110000110101001000101110. This is shown in Table 1.
- Demodulator 105 During operation of receiver 100, the chip stream output from AfD converter 104 enters demodulator 105 where symbol information is recovered from the chip values.
- Demodulator 105 typically includes a symbol synchronizer 113 that identifies which of the chip samples constitute a received symbol, as well as a correlator 115 that multiplies received chip samples by one or more stored PN sequences in order to recover symbol information. It is obvious to one of ordinary skill in the art that the correlator function described here is equivalent to a DSSS de-spreading operation, in which a PN sequence representing one of the transmitted symbols is multiplied by the received chip sequence and the result is integrated over the symbol period.
- the demodulator also typically includes a decision element 117 that operates on correlation values and outputs symbol information.
- the symbol information produced by the decision element may be a hard-decision estimate of the transmitted data symbol, or it may include soft-decision values, such correlation or other confidence values associated with one or more data symbols.
- the symbol information produced by the decision element may include signal parameters such as amplitude and phase used to characterize the communication link.
- the radio-frequency front end of the receiver typically consumes the most power. Reduction of this power is very desirable.
- demodulator 105 may perform a partial correlation on the first M chips of a symbol, where M may be much less than N, the total number of chips representing a symbol. If an acceptable partial correlation is made, short time constant, high power consumption circuits, such as receiver front end 103, may be set to a low-power state for the remainder of the symbol, and then returned to normal operating power prior to the beginning of the next symbol. This can significantly reduce power consumption of the receiver.
- receiver 100 Since receiver 100 relies on fewer chips to determine the sent data, the above- described technique is less sensitive than conventional DSSS detection. The effects of noise must be considered to ensure that poor signal conditions do not result in corrupted symbol information being output from demodulator 105.
- One technique that can be used to ensure the validity of symbols being output from demodulator 105 is to track a received signal characteristic to determine that a signal with an adequate quality is being received and to tailor operation of demodulator 105 to the received signal quality. Examples of received signal characteristics include received signal strength indication (RSSI), signal-to-noise ratio (SNR), and frequency error between transmitter and receiver. Such characteristics are typically measured using RF processing circuitry 103, demodulator 105, or a combination of both.
- RSSI received signal strength indication
- SNR signal-to-noise ratio
- frequency error between transmitter and receiver Such characteristics are typically measured using RF processing circuitry 103, demodulator 105, or a combination of both.
- bit error detection metrics can also be used as an indicator of received signal quality.
- FEC forward error correction
- CRC cyclic redundancy check
- bit error detection metrics can also be used as an indicator of received signal quality.
- FEC forward error correction
- CRC cyclic redundancy check
- bit error detection metrics can also be used as an indicator of received signal quality.
- M may be increased.
- a receive signal characteristic 123 will be provided to decision circuitry 117.
- Decision circuitry 117 will instruct correlator 115 to pass correlation values of the first M chips, with M being based on signal characteristic 123.
- correlation circuitry 115 is utilized to produce partial correlation values.
- the partial correlation values themselves may be utilized to provide a more immediate indication of signal quality.
- the partial correlation values are computed as
- * is the complex conjugate operator.
- the partial correlation value will be 7 for data symbol 0, since 7 of 8 possible chip values were correct.
- the partial correlation value will be 6 for data symbol 1, 2 for data symbol 2, . . . , etc.
- Demodulator 105 and particularly decision circuitry 117, will evaluate the 8- chip correlation values to determine if a desired criterion is met. If multiple correlation values are available during each symbol, such as in the modulation scheme depicted in Table 1, then an example of the desired criterion is that the largest partial correlation value must exceed a threshold. If only a single partial correlation result is available, such as phase shift key (PSK) modulation where a single chip sequence is phase-modulated by the symbol information, then an example of the desired criterion is that the partial correlation magnitude exceeds a threshold.
- PSK phase shift key
- decision circuitry 117 instructs correlator 115 to continue accumulating chips, until it has received a total of 16 chips. Decision circuitry 117 then attempts a second partial correlation, this time on the first 16 chips of each possible sequence; again, the partial correlation results are only accepted by circuitry 117 if the partial correlation values meet a desired criterion. If the desired criterion is not met, correlator 115 continues to receive chips, until it has received a total of 32 chips (the complete symbol). At this point decision circuitry 117 outputs the symbol information.
- partial correlations of 8 chips and 16 chips are used in the above example, the invention may be implemented more generally with different partial correlation lengths as well as fewer or more stages of partial correlation evaluation.
- decision circuitry 117 determines that an acceptable partial correlation has been made, decision circuitry 117 outputs the corresponding symbol information and additionally instructs circuitry to enter a low- power state via a power control signal 121. If there are additional symbols to be demodulated, the circuitry will be instructed to return to normal operation power in time to receive the first chip of the next symbol.
- demodulator 105 detects 11011001 for the first eight chips, it will stop accumulating chips and output symbol 0. Also, circuitry such as RF amplifiers 107, frequency translation circuitry 111, and ATD converters 104 will be instructed to enter a reduced power state. Then demodulator 105 will wait for approximately N-M (24) chip times, minus any circuit warm-up times, and then will instruct the circuitry to return to normal operating power.
- FIG. 2 is a flow chart showing operation of demodulator 105.
- the logic flow described in FIG. 2 can be performed when either partial correlation is being used to determine a number of chips (M) to accumulate, or may be used to determine the number of chips to accumulate when signal strength is being utilized to determine M. Regardless of the technique utilized, the logic flow begins at step 201.
- receiver 100 is placed in a standard (i.e., not a low power) operating state.
- a digital stream is received by synchronizer 113 that represents a chip stream. As discussed above, the stream may comprise a number of samples per chip, or may simply comprise the actual chip stream.
- correlator 115 receives a predetermined number (M) of chips, where M ⁇ N and determines partial correlation values of the M chips with all possible symbols, (step 209). (As discussed, symbols comprise M chips, with the partial correlation value being performed on less than N chips). The accumulated chips and the partial correlation values are passed to decision circuitry 117 where it is determined if a desired criterion has been met (step 211).
- the desired criterion may comprise an indication if a partial correlation value passes a predetermined quality threshold, or alternatively may comprise an indication if signal strength is above a criterion.
- decision circuitry 117 then may determine if the value of the signal characteristic passes a criteria,
- decision circuitry 117 associates the received chips (e.g., M chips) from the chip stream with a symbol and causes receiver 100 to operate in a low-power state (step 213) and outputs symbol information based on the partially-received chip stream (step 217).
- the received chips e.g., M chips
- receiver 100 causes receiver 100 to operate in a low-power state (step 213) and outputs symbol information based on the partially-received chip stream (step 217).
- at least one component within the receiver front end is placed in a low power state until a beginning of a next symbol period.
- Such components include amplifiers, filters, frequency translation circuitry, analog-to-digital conversion circuitry, . . . , etc.
- step 223 a low-power state remains until the beginning of the next symbol (e.g, a time period related to a time it takes to receive N-M chips). If all symbols have been received (step 227), the logic flow ends at step 229; however, if all symbols have not been received the logic flow returns to step 203 where the receiver is placed in a standard (i.e., not a low power) operating state. Returning to step 211, if it is determined that the desired quality criterion has not been met, the logic flow continues to step 219 where decision circuitry 117 determines if all chips have been received.
- step 221 If all chips have not been received, the logic flow continues to step 221 where more chips are accumulated by correlator 115 and the logic flow returns to step 209. If, however, it is determined that all chips have been received, the logic flow continues to step 215 where symbol information is associated to the received chips and output by decision circuitry 117. The logic flow continues to step 227.
Abstract
Description
Claims
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB0800031A GB2441289B (en) | 2005-07-18 | 2006-06-06 | Method and apparatus for reducing power consumption within a wireless receiver |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US11/183,683 US7339976B2 (en) | 2005-07-18 | 2005-07-18 | Method and apparatus for reducing power consumption within a wireless receiver |
US11/183,683 | 2005-07-18 |
Publications (1)
Publication Number | Publication Date |
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WO2007011469A1 true WO2007011469A1 (en) | 2007-01-25 |
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ID=37661618
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Application Number | Title | Priority Date | Filing Date |
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PCT/US2006/021972 WO2007011469A1 (en) | 2005-07-18 | 2006-06-06 | Method and apparatus for reducing power consumption within a wireless receiver |
Country Status (4)
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US (1) | US7339976B2 (en) |
GB (1) | GB2441289B (en) |
TW (1) | TW200711408A (en) |
WO (1) | WO2007011469A1 (en) |
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JP5734546B2 (en) * | 2009-02-25 | 2015-06-17 | 京セラ株式会社 | Object display device |
US10268805B2 (en) * | 2010-01-26 | 2019-04-23 | At&T Intellectual Property I, L.P. | System and method for providing multimedia digital rights transfer |
EP2530864A1 (en) * | 2011-06-03 | 2012-12-05 | TELEFONAKTIEBOLAGET LM ERICSSON (publ) | Apparatus and Method for Power Saving |
TWI477974B (en) | 2013-09-02 | 2015-03-21 | Via Tech Inc | Electronic device and method for reducing power consumption of electronic device |
FR3022712A1 (en) | 2014-06-20 | 2015-12-25 | Commissariat Energie Atomique | SELF-ADAPTIVE DEMODULATION METHOD OF QUASI-ORTHOGONAL SIGNALS, DEMODULATION UNIT AND RADIO SIGNAL RECEIVER |
GB2528499B (en) * | 2014-07-24 | 2021-03-31 | Advanced Risc Mach Ltd | Correlation determination early termination |
Citations (1)
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US6889055B1 (en) * | 2000-10-16 | 2005-05-03 | Qualcomm Inc. | Technique for reducing average power consumption in a wireless communications device |
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US4996526A (en) * | 1988-12-01 | 1991-02-26 | Motorola, Inc. | Power conservation method and apparatus for a portion of a synchronous information signal |
ZA965340B (en) * | 1995-06-30 | 1997-01-27 | Interdigital Tech Corp | Code division multiple access (cdma) communication system |
US5757864A (en) * | 1995-08-17 | 1998-05-26 | Rockwell Semiconductor Systems, Inc. | Receiver with filters offset correction |
US6282181B1 (en) * | 1998-04-24 | 2001-08-28 | Ericsson Inc | Pseudorandom number sequence generation in radiocommunication systems |
US6421371B1 (en) * | 1998-11-17 | 2002-07-16 | Ericsson Inc. | Modulation sequence synchronization methods and apparatus employing partial sequence correlation |
KR100450789B1 (en) * | 1999-05-25 | 2004-10-01 | 삼성전자주식회사 | Apparatus for acquiring PN code and DS-CDMA receiver comprising it |
US6965632B2 (en) * | 2001-06-08 | 2005-11-15 | Sony Corporation | Method and apparatus for using adaptive threshold with initial acquisition |
US7171605B2 (en) * | 2002-02-01 | 2007-01-30 | International Business Machines Corporation | Check bit free error correction for sleep mode data retention |
US6748009B2 (en) * | 2002-02-12 | 2004-06-08 | Interdigital Technology Corporation | Receiver for wireless telecommunication stations and method |
JP2006041797A (en) * | 2004-07-26 | 2006-02-09 | Oki Electric Ind Co Ltd | Inverse spread apparatus and method in spread spectrum communication |
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2005
- 2005-07-18 US US11/183,683 patent/US7339976B2/en active Active
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2006
- 2006-06-06 GB GB0800031A patent/GB2441289B/en active Active
- 2006-06-06 WO PCT/US2006/021972 patent/WO2007011469A1/en active Application Filing
- 2006-06-21 TW TW095122328A patent/TW200711408A/en unknown
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US6889055B1 (en) * | 2000-10-16 | 2005-05-03 | Qualcomm Inc. | Technique for reducing average power consumption in a wireless communications device |
Also Published As
Publication number | Publication date |
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US20070014335A1 (en) | 2007-01-18 |
TW200711408A (en) | 2007-03-16 |
GB2441289B (en) | 2009-10-28 |
GB0800031D0 (en) | 2008-02-13 |
GB2441289A (en) | 2008-02-27 |
US7339976B2 (en) | 2008-03-04 |
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