`
`EXHIBIT
`
`EXHIBIT
`DSS-2004
`
`DSS-2 004
`
`

`
`US007558232B2
`US007558232B2
`
`(12) Ulllted States Patent
`(12) United States Patent
`Pearl
`Pearl
`
`(10) Patent N0.:
`(10) Patent N0.:
`(45) Date of Patent:
`(45) Date of Patent:
`
`US 7,558,232 B2
`US 7,558,232 B2
`*Jul. 7, 2009
`*Jul. 7, 2009
`
`(54) ADAPTIVE DUTY CYCLE MANAGEMENT
`(54) ADAPTIVE DUTY CYCLE MANAGEMENT
`METHOD AND SYSTEM FOR RADIO
`METHOD AND SYSTEM FOR RADIO
`TRANSMITTERS
`TRANSMITTERS
`
`(75) Inventor: Norman Pearl, Montreal (CA)
`(75)
`Inventor: Norman Pearl, Montreal (CA)
`
`(73)
`Assignee: Dataradio, Inc., Montreal, Quebec (CA)
`(73) Assignee: Dataradio, Inc., Montreal, Quebec (CA)
`
`(*)
`Notice:
`( * ) Notice;
`
`Subject to any disclaimer, the term of this
`Subject to any disclaimer’ the term ofthis
`patent is extended or adjusted under 35
`patent is extended or adjusted under 35
`U.S.C. l54(b) by 577 days.
`IJ'S'C~ 154(1)) by 577 days'
`
`This patent is subject to a terminal dis-
`This patent is subject to a terminal dis
`claimer.
`C1a1mer~
`
`(21)
`Appl. No.: 11/223,221
`(21) Appl. N0.: 11/223,221
`
`_
`-
`Filed:
`(22)
`(22) Flled'
`(65)
`(65)
`
`Sep. 9, 2005
`sep' 9’ 2005
`Prior Publication Data
`Prior Publication Data
`US 2006/0067245 A1
`Mar. 30, 2006
`US 2006/0067245 A1 M . 30 2006
`ar
`’
`Related U.S. Application Data
`Related US. Application Data
`
`(63) Continuation-in-part of application No. 09/854,610,
`(63) Continuation-in-part of application No. 09/854,610,
`filed on May 14, 2001, now Pat. No. 6,950,404.
`?led on May 14, 2001, noW Pat. No. 6,950,404.
`Int. Cl.
`(51) Int Cl
`(51)
`H04B 7/212
`(2006 01)
`H0213 012
`(2006.01)
`(200601)
`H04B 7/00
`(2006.01)
`H04B 7/00
`(200601)
`H04] 3/00
`(2006.01)
`H04] 3/00
`_
`_
`_
`'
`U.S. Cl.
`..................... .. 370/321; 370/337; 370/345;
`(52)
`(52) US. Cl. ..................... .. 370/321, 370/337, 347505//354252,
`455/522
`_
`_
`_
`Field of Classification Search ............... .. 370/314,
`(58)
`(58) Field of Classi?cation Search ............... .. 370/314,
`370/318, 321, 326, 336—337, 345, 347, 277—278,
`370618’ 321’ 326’ 336%?7’ 345’ 347’ 277T278’
`370/282, 442, 498; 455/13.4, 522, 127.1,
`370/282’ 442’ 498’ 455/13'4’ 522’ 127'1’
`455/ 127.5
`_
`_ 45 5/127'5
`_
`See application file for complete search history.
`See apphcanon ?le for Complete Search hlstory'
`References Cited
`References Cited
`U.S. PATENT DOCUMENTS
`US. PATENT DOCUMENTS
`5,127,036 A
`6/1992 Pham
`5,127,036 A
`6/1992 Pham
`
`(56)
`(56)
`
`7/1992 Freeburg et al.
`5,134,615 A
`7/1992 Freeburg et al.
`5,134,615 A
`9/1994 Hullett et al.
`5,351,043 A
`9/1994 Hullett et al.
`5,351,043 A
`6/1996 Lindell
`5,524,275 A
`6/1996 Lindell
`5,524,275 A
`8/2000 Carkner et al.
`6,104,759 A
`8/2000 Carkner et al.
`6,104,759 A
`9/2000 Chuah
`6,115,390 A
`9/2000 Chuah
`6,115,390 A
`9/2000 Sears
`6,122,492 A
`9/2000 Sears
`6,122,492 A
`10/2000 Lee
`6,127,861 A
`6,127,861 A 10/2000 Lee
`6,144,193 A
`11/2000 Illingworth
`6,144,193 A 11/2000 IllingWoIth
`6,477,160 B2 * 11/2002 Gleeson .................... .. 370/337
`6,477,160 B2 * 11/2002 Gleeson .................... .. 370/337
`6,950,404 B2*
`9/2005 Pearl
`........................ .. 370/252
`6,950,404 B2* 9/2005 Pearl ........................ .. 370/252
`7,245,880 B1*
`7/2007 Jacobsen ................... .. 455/69
`7,245,880 B1 *
`7/2007 Jacobsen ................... .. 455/69
`7,330,706 B2 *
`2/2008 Gentsch et al.
`........ .. 455/127.1
`7,330,706 B2 *
`2/2008 Gentsch et al. ........ .. 455/127.1
`
`(Continued)
`(Continued)
`OTHER PUBLICATIONS
`OTHER PUBLICATIONS
`U.S. Code of Federal Regulations, Title 47, Part 1, Paragraph 1310
`US. Code of Federal Regulations, Title 47, Part 1, Paragraph 1310
`(47C.F.R.1.1310) Radiofrequency Radiation Exposure Limits; Jul.
`(47C.F.R.1.1310) Radiofrequency Radiation Exposure Limits; Jul.
`10, 2001.
`10’ 2001'
`Primary Examiner—Tri H Phan
`Primar ExamineriTri H Phan
`y
`(74) Attorney, Agent, or Firm—Koppel, Patrick, Heybl &
`(74) Attorney, Agent, or FirmiKoppel, Patrick, Heybl &
`Dawson
`Dawson
`
`(57)
`(57)
`
`ABSTRACT
`ABSTRACT
`
`A duty cycle management system and method for use in a
`A duty cycle management system and method for use in a
`wireless device having a transmitter which transmits packets
`Wireless device having a transmitter Which transmits packets
`in the form of individual packets and/or packet bursts. A
`in the form of individual packets and/or packet bursts. A
`controller in combination with an instruction set limits the
`controller in combination With an instruction set limits the
`number of packets transmitted during each time period
`number of packets transmitted during each time period
`defined by one time window or adjacent time windows, on a
`de?ned by one time Window or adjacent time Windows, on a
`sliding basis, so as to control the duty cycle of transmissions
`sliding basis, so as to control the duty cycle of transmissions
`during successive adjacent time windows based on the trans-
`during Successive adjacent time Windows based on the trans_
`mitter’s output poWer, to produce that average poWer output.
`mitter’ s output power, to produce that average power output.
`The transmission of packets is thereby delayed as needed to
`The transmission of packets is thereby delayed as needed to
`establish sufficient idle period(s) during one time window or
`establish su?icient idle period(s) during one time WindoW or
`adjacent time WindoWs to apply Whatever duty cycle is
`adjacent time windows to apply whatever duty cycle is
`needed to produce that average power output level limit for
`needed to produce that average poWer output level limit for
`the transmitter.
`the transmitter.
`
`17 Claims, 4 Drawing Sheets
`17 Claims, 4 Drawing Sheets
`
`ON EACH TIMESLOT
`REGENING
`NTIMESLOT12
`
`ON EACH TIMESLOT
`
`RECElVlNG
`N TIMEsLOT
`'_‘ 12
`
`
`
`‘MAX = MAXIMUM
`COUNTERAMOUNT
`
`
`‘MAX = MAXIMUM
`COUNTER AMOUNT
`
`
`
`co NT=
`U
`COUNT-DC
`
`
`
`BURST
`SEND
`
`SEND
`BURST
`
`;
`couN'r =
`COUNT e Ic
`
`I
`COUNT =
`COUNT +10
`
`SEND 1
`
`
`SEND 1
`PACKET
`
`COUNT =
`COUNT ' 1C
`
`
`
`ls
`| UNT 0 NO. 0
`PACKETS lN
`BURST X lc
`SMAX'?
`
`SEND
`
`BURST Is
`NOTALLOWED PACKET
`
`BURST X Ic
`sMAx7
`y
`SEND BURST
`TRANSMIT ONE
` TRANSMIT ONE
`PACKET
`PACKET
`k17
`PACKET
`
`

`
`US 7,558,232 B2
`US 7,558,232 B2
`Page 2
`Page 2
`
`U.S. PATENT DOCUMENTS
`US. PATENT DOCUMENTS
`2002/0110085 A1
`8/2002 H0 et al.
`2002/0110085 A1
`8/2002 H0 et a1.
`2004/0137861 A1*
`7/2004 Gentsch et al.
`........ .. 455/127.1
`2004/0137861 A1 *
`7/2004 Gentsch et a1. ........ .. 455/l27.l
`
`2006/0203795 A1*
`2006/0203795 A1 *
`
`9/2006 Welborn et al.
`........... .. 370/345
`9/2006 Welborn et a1. ........... .. 370/345
`
`* cited by examiner
`* cited by examiner
`
`

`
`US. Patent
`U.S. Patent
`
`Jul. 7, 2009
`Jul. 7, 2009
`
`Sheet 1 of4
`Sheet 1 of4
`
`US 7,558,232 B2
`US 7,558,232 B2
`
`2
`
`21
`
`4
`
`4X /
`
`TO ANTENNA
`TO ANTENNA
`
` COUNTER
`TRANSMITTER —>
`COUNTER
`TRANSMITTER
`
`l
`
`A
`
`INIT
`lNlT OUT -
`
`+
`
`6\
`
`N
`
`7
`\
`
`<—> |/o
`
`
`CONTROLLER
`CONTROLLER
`I
`
`
`
`MEMORY
`4———> MEMORY
`
`9)
`
`FROM ANTENNA
`FROM ANTENNA
`RECEIVER
`RECEIVER
`
`
`FIG. 1
`FIG. 1
`
`

`
`US. Patent
`U.S. Patent
`
`Jul. 7, 2009
`Jul. 7, 2009
`
`Sheet 2 of4
`Sheet 2 of4
`
`US 7,558,232 B2
`US 7,558,232 B2
`
`ON EACH TIMESLOT
`ON EACH TIMESLOT
`13
`13
`
`RECEIVING
`RECEIVING
`TIMESLOT
`TIMESLOT
`
`SEND
`SEND
`
`Y
`Y
`
`11
`11
`
`DO NOT
`SEND
`N
`
`COUNT5MAX*
`
`Y OKAY TO SEND
`
`
`
`*MAX = MAXIMUM
`*MAX = MAXIMUM
`COUNTER AMOUNT
`COUNTER AMOUNT
`
`Y
`Y
`
`19
`
`
`
`
`
`
`
`IS
`IS
`COUNT + NO. O
`V
`SEND
`COUNT + No. 0
`
`PACKETS IN
`PACKETS IN
`SINGLE
`
`BURST IS
`BURST IS
`BURST X IC
`NOT ALLOWED PACKET
`COUNT =
`BURST X '6
`NOT ALLOWED PACKET
`COUNT =
`SMAX?
`SMAX?
`
`
`COUNT-DC
`COUNT-DC
`
`
`SEND BURST
`SEND BURST
`
`
`
`
`
`
`
`K17
`
`
`
`
`TRANSMIT ONE
`
`TRANSMIT ONE
`TRANSMIT ONE
`TRANSMIT ONE
`PACKET
`PACKET
`PACKET
`PACKET
`
`
`17
`
`
`
`
`I
`
`SEND 1
`SEND 1
`PACKET
`PACKET
`
`COUNT =
`COUNT =
`COUNT + IC
`COUNT + IC
`
`k16
`
`FIG. 2A
`Y
`
`SEND
`BURST
`
`‘
`
`
`
`COUNT =
`COUNT =
`COUNT + IC
`COUNT + IC
`
`

`
`US. Patent
`U.S. Patent
`
`Jul. 7, 2009
`Jul. 7, 2009
`
`Sheet 3 of4
`Sheet 3 0f 4
`
`US 7,558,232 B2
`US 7,558,232 B2
`
`ON EACH TIMESLOT
`ON EACH TIMESLOT
`
`DATA TO
`SEND?
`
`*MAX = MAXIMUM
`*MAX = MAXIMUM
`COUNTER AMOUNT
`COUNTER AMOUNT
`
`COUNTsMAX*?
`
`BURST
`BURST
`DESIRED?
`DESIRED?
`
`20
`
`COUNT = 0
`COUNT = 0
`FOR PREVIOUS
`FOR PREVIOUS
`WINDOW?
`WINDOW?
`
`COUNT = COUNT
`COUNT = COUNT
`+(ICXBURST)
`+(|CxBURST)
`
`30)
`
`COUNT =
`COUNT =
`COUNT+(ICX2X
`COUNT+(lCx2x
`BURST)
`BURST)
`\35 ,
`
`SEND BURST
`SEND BURST
`
`TRANSMIT ONE
`TRANSMIT ONE
`PACKET
`PACKET
`
`Y
`
`COUNT =
`COUNT =
`COUNT-DC
`COUNT-DC
`
`K17
`
`I
`
`COUNT =
`COUNT =
`COUNT + IC
`COUNT + IC
`
`K16
`
`FIG. 25
`
`

`
`US. Patent
`U.S. Patent
`
`Jul. 7, 2009
`Jul. 7, 2009
`
`Sheet 4 of4
`Sheet 4 of4
`
`US 7,558,232 B2
`US 7,558,232 B2
`
`COUNT
`COUNT
`2 x MAXIMUM COUNTER AMOUNT
`A 2 x MAXIMUM COUNLEEAMOUNL _ _ _ _ _ _ _ _ __ ._
`
`TRANSMISSION
`TRANSMISSION
`INHIBI'ITED
`INHIBITTED
`
`MAXIMUM COUNTER AMOUN
`
`
`
`>
`
`l
`I
`I
`I
`x+1 1.2 SEC
`x+3 t
`x+2
`X+1 1-2 SEC
`x
`t
`x+2
`x+3
`«T» .
`’
`(min )
`OVER 2T,DC 5 2% MAX
`I"“”-I
`-
`OVER 2T,DC 5 2% MAX
`>
`<j———:j>
`OVER 2T,DC = 2% MAX
`OVER 2T,DC = 2% MAX
`
`FIG. 3A
`FIG . 3A
`
`COUNT
`COUNT
`2 x MAXIMUM COUNTER AMOUNT
`
`2 x MAXIMUM COUNTER AMOUNT
`
`
`
`D
`I
`I
`I
`I
`t
`x+3
`x+2
`x+1 1'2 SEC
`x
`X+3 t
`x+2
`x+1 1'2 SEC
`x
`
`(min )
`>
`(""“-)
`OVER 2T,DC 5 2% MAX
`'
`OVER 2T,DC 5 2% MAX
`D
`4%-A-D
`OVER 2T,DC s 2% MAX
`OVER 2T,DC s 2% MAX
`
`TRANSMISSION
`TRANSMISSION
`INHIBITTED
`INHIBITTED
`
`FIG. 3B
`FIG. 3B
`
`

`
`US 7,558,232 B2
`US 7,558,232 B2
`
`1
`1
`ADAPTIVE DUTY CYCLE MANAGEMENT
`ADAPTIVE DUTY CYCLE MANAGEMENT
`METHOD AND SYSTEM FOR RADIO
`METHOD AND SYSTEM FOR RADIO
`TRANSMITTERS
`TRANSMITTERS
`
`RELATED APPLICATION
`RELATED APPLICATION
`
`This application is a continuation-in-part application of
`This application is a continuation-in-part application of
`application Ser. No. 09/854,610 filed on 14 May, 2001 now
`application Ser. No. 09/854,610 ?led on 14 May, 2001 now
`U.S. Pat. No. 6,950,404.
`US. Pat. No. 6,950,404.
`
`FIELD OF INVENTION
`FIELD OF INVENTION
`
`The present invention is directed to management of the
`The present invention is directed to management of the
`duty cycle ofwireless data transmissions and, in particular, to
`duty cycle of Wireless data transmissions and, in particular, to
`an adaptive duty cycle management method and system for
`an adaptive duty cycle management method and system for
`digital radio frequency (RF) transmitters which control the
`digital radio frequency (RF) transmitters Which control the
`duty cycle on a sliding window basis to a preselected maxi-
`duty cycle on a sliding WindoW basis to a preselected maxi
`mum or varying amount depending on the applicable output
`mum or varying amount depending on the applicable output
`power limit(s).
`poWer limit(s).
`BACKGROUND OF THE INVENTION
`BACKGROUND OF THE INVENTION
`
`There exists a concern regarding the safety to users of
`There exists a concern regarding the safety to users of
`wireless communications devices, such as mobile radios and
`Wireless communications devices, such as mobile radios and
`cellular telephones, when these devices are operated in their
`cellular telephones, When these devices are operated in their
`transmit mode by reason that it is perceived the electromag-
`transmit mode by reason that it is perceived the electromag
`netic radiation associated with the transmission of the signals
`netic radiation associated With the transmission of the signals
`from such devices may pose a potential health hazard to the
`from such devices may pose a potential health haZard to the
`user. When using a hand-held wireless device the user holds
`user. When using a hand-held Wireless device the user holds
`the device near the ear and this positions the devices trans-
`the device near the ear and this positions the devices trans
`mission antenna in close proximity to the user’s hand and
`mission antenna in close proximity to the user’s hand and
`head as it transmits electromagnetic radiation and it is postu-
`head as it transmits electromagnetic radiation and it is postu
`lated that a portion of this radiation may be absorbed by the
`lated that a portion of this radiation may be absorbed by the
`head and hand and that such absorption may cause health
`head and hand and that such absorption may cause health
`risks to the user. The perceived potential health hazard asso-
`risks to the user. The perceived potential health haZard asso
`ciated with wireless transmitting devices increases as the
`ciated With Wireless transmitting devices increases as the
`power of the signals transmitted from the device increases.
`poWer of the signals transmitted from the device increases.
`To address this perceived health risk many countries have
`To address this perceived health risk many countries have
`adopted legislation requiring that the effective radiated power
`adopted legislation requiring that the effective radiated poWer
`(ERP) ofwireless devices be limited. For instance, theAmeri-
`(ERP) of Wireless devices be limited. For instance, theAmeri
`can National Standards Institute (ANSI) in association with
`can National Standards Institute (ANSI) in association With
`the Institute of Electrical and Electronic Engineers, Inc.
`the Institute of Electrical and Electronic Engineers, Inc.
`(IEEE) has adopted new standards for RF exposure viz.
`(IEEE) has adopted neW standards for RF exposure viZ.
`ANSI/IEEE C95.1-1992. The Federal Communications
`ANSI/IEEE C95.1-1992. The Federal Communications
`Commission (FCC) has adopted limits for maximum permis-
`Commission (FCC) has adopted limits for maximum permis
`sible exposure (MPE) time which, generally, are more restric-
`sible expo sure (MPE) time Which, generally, are more restric
`tive than the previously adopted limits and guidelines and
`tive than the previously adopted limits and guidelines and
`apply to land-mobile systems, such as cellular radio, pocket
`apply to land-mobile systems, such as cellular radio, pocket
`and hand-held radio telephones. These limits are based on
`and hand-held radio telephones. These limits are based on
`recommended expo sure guidelines published by the National
`recommended expo sure guidelines published by the National
`Council on Radiation Protection and Measurements (NCRP)
`Council on Radiation Protection and Measurements (N CRP)
`in “Biological Effects and Exposure Criteria for Radio fre-
`in “Biological Effects and Exposure Criteria for Radio fre
`quency Electromagnetic Fields,” NCRP Report No. 86, Sec-
`quency Electromagnetic Fields,” NCRP Report No. 86, Sec
`tions 17.4.1, 17.4.1.1, 17.4.2 and 17.4.3. Copyright NCRP,
`tions 17.4.1, 17.4.1.1, 17.4.2 and 17.4.3. Copyright NCRP,
`1986, Bethesda, Md. 20814. The guidelines provide for
`1986, Bethesda, Md. 20814. The guidelines provide for
`exclusions to the regulations if it can be shown through labo-
`exclusions to the regulations if it can be shoWn through labo
`ratory procedures that exposure conditions do not exceed a
`ratory procedures that exposure conditions do not exceed a
`certain specific absorption rate (SAR) or, alternatively, if the
`certain speci?c absorption rate (SAR) or, alternatively, if the
`radiated power is below a certain level.
`radiated poWer is beloW a certain level.
`A quantification of MPE for uncontrolled environments is
`A quanti?cation of MPE for uncontrolled environments is
`based on, inter alia, the electric and magnetic field strengths,
`based on, inter alia, the electric and magnetic ?eld strengths,
`the power density, the frequency range of the radio signal, the
`the poWer density, the frequency range of the radio signal, the
`distance between the user’ s head and the transmitter radiating
`distance betWeen the user’ s head and the transmitter radiating
`point. Thus, the MPE can be correlated to a maximum per-
`point. Thus, the MPE can be correlated to a maximum per
`mitted transmission power, which may vary with the fre-
`mitted transmission poWer, Which may vary With the fre
`quency range of a wireless device.
`quency range of a Wireless device.
`
`2
`2
`One method of meeting the applicable MPE limitations is
`One method of meeting the applicable MPE limitations is
`to reduce the duty cycle of the transmitter. While techniques
`to reduce the duty cycle of the transmitter. While techniques
`such as TDM (time division multiplexing) inherently activate
`such as TDM (time division multiplexing) inherently activate
`the transmitter for less than 100% percentage of the total
`the transmitter for less than 100% percentage of the total
`communication time, it is not an easy task to reduce the duty
`communication time, it is not an easy task to reduce the duty
`cycle of the transmitter on a source basis (i.e. without regard
`cycle of the transmitter on a source basis (i.e. Without regard
`to network trafiic) in such a way as to effectively control the
`to netWork traf?c) in such a Way as to effectively control the
`duty cycle Without negatively degrading the performance of
`duty cycle without negatively degrading the performance of
`the network and without averaging duty cycles over unrea-
`the netWork and Without averaging duty cycles over unrea
`sonably long periods (tens ofminutes or hours). Instead, since
`sonably long periods (tens of minutes or hours). Instead, since
`data is randomly transmitted over various time intervals, it is
`data is randomly transmitted over various time intervals, it is
`desired that the wireless device itself limit the effective trans-
`desired that the Wireless device itself limit the effective trans
`mit (active) time.
`mit (active) time.
`Some wireless devices are further capable of transmitting
`Some Wireless devices are further capable of transmitting
`at several power levels, under command of a base station or
`at several poWer levels, under command of a base station or
`independently, such as reducing output power to conserve
`independently, such as reducing output poWer to conserve
`battery power when close to a base station, or increasing
`battery poWer When close to a base station, or increasing
`output power to overcome interference.
`output poWer to overcome interference.
`In order to address the foregoing need for an effective
`In order to address the foregoing need for an effective
`method and system for managing the duty cycle of a trans-
`method and system for managing the duty cycle of a trans
`mitter the inventor developed the subject matter herein which
`mitter the inventor developed the subject matter herein Which
`makes effective use the quiet time inherent during a transmis-
`makes effective use the quiet time inherent during a transmis
`sion.
`sion.
`
`SUMMARY OF THE INVENTION
`SUMMARY OF THE INVENTION
`
`The present invention provides a method and system for
`The present invention provides a method and system for
`adaptively limiting the duty cycle of a transmitter of a wire-
`adaptively limiting the duty cycle of a transmitter of a Wire
`less device in order to comply with MPE requirements while
`less device in order to comply With MPE requirements While
`preserving the ability to broadcast RF signals at a level suf-
`preserving the ability to broadcast RF signals at a level suf
`ficient to establish and/or maintain a quality radio link. This is
`?cient to establish and/ or maintain a quality radio link. This is
`achieved by sliding (moving) a reference window of time
`achieved by sliding (moving) a reference Window of time
`over which a preselected duty cycle is calculated (e.g. one
`over Which a preselected duty cycle is calculated (eg one
`minute), thereby taking advantage of any quiet time preced-
`minute), thereby taking advantage of any quiet time preced
`ing a burst, and afterwards enforcing only as much quiet time
`ing a burst, and afterWards enforcing only as much quiet time
`as required to meet the desired duty cycle limitation. The
`as required to meet the desired duty cycle limitation. The
`specific duty cycle to be imposed by the method and system
`speci?c duty cycle to be imposed by the method and system
`can be fixed for an application where the output power level is
`can be ?xed for an application Where the output poWer level is
`constant (i.e. a duty cycle of, say, 2% can be set as can a duty
`constant (i.e. a duty cycle of, say, 2% can be set as can a duty
`cycle of, say, 25%) or, alternatively, it can be varied where the
`cycle of, say, 25%) or, alternatively, it can be varied Where the
`transmitter output power is varying. This reflects the fact that
`transmitter output poWer is varying. This re?ects the fact that
`a duty cycle of, say, 25% at 50 W would result in the same
`a duty cycle of, say, 25% at 50 W Would result in the same
`average power output for a duty cycle of 50% at 25 W. The
`average poWer output for a duty cycle of 50% at 25 W. The
`resulting average power output is therefore also controllable
`resulting average poWer output is therefore also controllable
`by selecting the appropriate duty cycle. When the transmitter
`by selecting the appropriate duty cycle. When the transmitter
`power output is variable, it is the average power output which
`poWer output is variable, it is the average poWer output Which
`becomes the limiting value, and the allowed duty cycle
`becomes the limiting value, and the alloWed duty cycle
`becomes variable and a function of the actual (i.e. instanta-
`becomes variable and a function of the actual (i.e. instanta
`neous) power output (which is also variable) and the trans-
`neous) poWer output (Which is also variable) and the trans
`mission history, so as to remain within the allowable average
`mission history, so as to remain Within the alloWable average
`power output.
`poWer output.
`In accordance with the present invention there is provided
`In accordance With the present invention there is provided
`a duty cycle management system and method for use in a
`a duty cycle management system and method for use in a
`wireless device comprising a transmitter for transmitting
`Wireless device comprising a transmitter for transmitting
`packets in the form of individual packets and/or packet bursts
`packets in the form of individual packets and/or packet bursts
`comprising a predetermined maximum number ofcontiguous
`comprising a predetermined maximum number of conti guous
`packets. The transmitter is operable over a duration measur-
`packets. The transmitter is operable over a duration measur
`able as a series of contiguous time windows with each time
`able as a series of contiguous time WindoWs With each time
`window comprising a predetermined number oftimeslots and
`WindoW comprising a predetermined number of timeslots and
`each timeslot having a predetermined nominal duration. The
`each timeslot having a predetermined nominal duration. The
`transmitter is configured for transmitting one packet during
`transmitter is con?gured for transmitting one packet during
`one timeslot and has an associated average power output for
`one timeslot and has an associated average poWer output for
`the transmitted packets. A controller in combination with a
`the transmitted packets. A controller in combination With a
`storage medium containing instructions executable by the
`storage medium containing instructions executable by the
`controller limits the number of packets transmitted during
`controller limits the number of packets transmitted during
`each time period defined by one time window or adjacent time
`each time period de?ned by one time WindoW or adjacent time
`windows, on a sliding basis, so as to control the duty cycle of
`WindoWs, on a sliding basis, so as to control the duty cycle of
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`US 7,558,232 B2
`US 7,558,232 B2
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`transmissions during successive adj acent time window(s)
`transmissions during successive adj acent time window(s)
`based on the transmitter power output to produce that asso-
`based on the transmitter power output to produce that asso
`ciated (applied) average power output. In doing so the trans-
`ciated (applied) average power output. In doing so the trans
`mission of packets is delayed as needed to establish sufficient
`mission of packets is delayed as needed to establish suf?cient
`idle period(s) during adjacent time windows to apply what-
`idle period(s) during adjacent time windows to apply what
`ever duty cycle is needed to produce that average power
`ever duty cycle is needed to produce that average power
`output.
`output.
`The controller identifies prior to the transmission of a
`The controller identi?es prior to the transmission of a
`packet whether such packet is an individual packet or a burst
`packet whether such packet is an individual packet or a burst
`packet. A counter is used in the preferred embodiment for
`packet. A counter is used in the preferred embodiment for
`keeping a running count which may be correlated to the duty
`keeping a running count which may be correlated to the duty
`cycle over one or more time windows. The counter is incre-
`cycle over one or more time windows. The counter is incre
`mented by an amount of either IC or two times IC for each
`mented by an amount of either IC or two times IC for each
`timeslot in which a packet is transmitted and is decremented
`timeslot in which a packet is transmitted and is decremented
`by an amount DC for each idle timeslot, whereby the ratio of
`by an amount DC for each idle timeslot, whereby the ratio of
`IC to DC is the duty cycle to be applied. For a transmitter
`IC to DC is the duty cycle to be applied. For a transmitter
`capable of operating at various output power levels a corre-
`capable of operating at various output power levels a corre
`sponding value of amount IC is provided (and stored) for
`sponding value of amount IC is provided (and stored) for
`every output power level. For an individual packet, transmis-
`every output power level. For an individual packet, transmis
`sion ofthe packet is permitted when the counter amount does
`sion of the packet is permitted when the counter amount does
`not exceed a maximum counter amount equal to the prede-
`not exceed a maximum counter amount equal to the prede
`termined number of timeslots per time window. However,
`termined number of timeslots per time window. However,
`transmission of the packet
`is delayed when the counter
`transmission of the packet is delayed when the counter
`amount has reached that maximum counter amount (viz. the
`amount has reached that maximum counter amount (viZ. the
`predetermined number of timeslots per time window) until
`predetermined number of timeslots per time window) until
`the counter amount
`falls below the maximum counter
`the counter amount falls below the maximum counter
`amount. For a burst packet, the controller tests, by determin-
`amount. For a burst packet, the controller tests, by determin
`ing whether the counter amount plus the number ofpackets in
`ing whether the counter amount plus the number of packets in
`the burst times IC is equal to or greater than the maximum
`the burst times IC is equal to or greater than the maximum
`counter amount, whether transmission ofthe number ofpack-
`counter amount, whether transmission of the number of pack
`ets in the burst would cause the counter amount to reach the
`ets in the burst would cause the counter amount to reach the
`maximum counter amount. If it would only an individual
`maximum counter amount. If it would only an individual
`packet is transmitted (not the burst) and ifit wouldn’t the burst
`packet is transmitted (not the burst) and if it wouldn’t the burst
`is transmitted. In a special case where the duty cycle is so low
`is transmitted. In a special case where the duty cycle is so low
`that transmission of a single packet burst within one time
`that transmission of a single packet burst within one time
`window would increase the counter amount by an amount
`window would increase the counter amount by an amount
`near or equal to the maximum counter amount, the controller
`near or equal to the maximum counter amount, the controller
`permits transmission of the burst packets only if the counter
`permits transmission of the burst packets only if the counter
`amount is zero and, ifthe counter amount has been zero for at
`amount is Zero and, if the counter amount has been Zero for at
`least a number of timeslots equal to the predetermined num-
`least a number of timeslots equal to the predetermined num
`ber of timeslots per time window, the counter is incremented
`ber of timeslots per time window, the counter is incremented
`by IC or, if the counter amount has not been zero for at least
`by IC or, if the counter amount has not been Zero for at least
`a number of timeslots equal to the predetermined number of
`a number of timeslots equal to the predetermined number of
`timeslots per time window, the counter is incremented by two
`timeslots per time window, the counter is incremented by two
`times IC.
`times IC.
`Preferably, the controller in combination with the instruc-
`Preferably, the controller in combination with the instruc
`tions is configured for providing priority, for transmission, to
`tions is con?gured for providing priority, for transmission, to
`a predetermined maximum number of acknowledgement
`a predetermined maximum number of acknowledgement
`packets by permitting transmission of up to maximum num-
`packets by permitting transmission of up to maximum num
`ber of acknowledgement packets when the counter amount is
`ber of acknowledgement packets when the counter amount is
`equal to or greater than IC/DC times the maximum number of
`equal to or greater than IC/ DC times the maximum number of
`packets per packet burst but less than a predetermined maxi-
`packets per packet burst but less than a predetermined maxi
`mum count.
`mum count.
`Advantageously,
`the invention provides for a wireless
`Advantageously, the invention provides for a wireless
`transmission not exceeding an established duty cycle limit
`transmission not exceeding an established duty cycle limit
`based on short fixed-length windows of time, while permit-
`based on short ?xed-length windows of time, while permit
`ting longer transmission times in the form ofbursts in order to
`ting longer transmission times in the form of bursts in order to
`improve response times. This results in a greater range of
`improve response times. This results in a greater range of
`power output, which maximizes transmitter’s ability to main-
`power output, which maximiZes transmitter’s ability to main
`tain quality radio links while avoiding possible detrimental
`tain quality radio links while avoiding possible detrimental
`effects associated with uncontrolled radiation environments.
`effects associated with uncontrolled radiation environments.
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`BRIEF DESCRIPTION OF THE DRAWINGS
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`A preferred embodiment of the invention is described
`A preferred embodiment of the invention is described
`below, by way of example only and without intending to limit
`below, by way of example only and without intending to limit
`the scope of the invention claimed herein, with reference to
`the scope of the invention claimed herein, with reference to
`the following drawings.
`the following drawings.
`FIG. 1 is a block diagram of the adaptive duty cycle man-
`FIG. 1 is a block diagram of the adaptive duty cycle man
`agement system components of a digital wireless device
`agement system components of a digital wireless device
`(such as a private network mobile radio unit or public network
`(such as a private network mobile radio unit or public network
`wireless phone) in accordance with the invention;
`wireless phone) in accordance with the invention;
`FIG. 2(a) is a flow chart of the steps performed by the
`FIG. 2(a) is a ?ow chart of the steps performed by the
`adaptive duty cycle management system shown in FIG. 1
`adaptive duty cycle management system shown in FIG. 1
`whereby a relatively high duty cycle, e. g. 25%, is applied and
`whereby a relatively high duty cycle, e. g. 25%, is applied and
`FIG. 2(b) is a flow chart showing the special case steps per-
`FIG. 2(b) is a ?ow chart showing the special case steps per
`formed by the adaptive duty cycle management system
`formed by the adaptive duty cycle management system
`whereby a relatively low duty cycle, e. g. 2%, is applied such
`whereby a relatively low duty cycle, e. g. 2%, is applied such
`that transmission of a single packet burst within a number of
`that transmission of a single packet burst within a number of
`timeslots equal to the predetermined number of timeslots per
`timeslots equal to the predetermined number of timeslots per
`time window would increase the counter amount by an
`time window would increase the counter amount by an
`amount near or equal to the maximum counter amount;
`amount near or equal to the maximum counter amount;
`FIGS. 3(a) and 3(b) are graphs showing the count patt