(12) United States Patent
`Tong et al.
`
`USOO6529741B1
`(10) Patent No.:
`US 6,529,741 B1
`(45) Date of Patent:
`*Mar. 4, 2003
`
`(54) MULTI-BIT POWER CONTROLAND POWER
`CONTROL COMMAND SUB-CHANNEL
`DESIGN
`
`(75) Inventors: Serg ya (CA); Evelyn Le
`rat, Paris (FR)
`(73) Assignee: Nortel Networks Ltd., St. Laurent
`(CA)
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 0 days.
`This patent is Subject to a terminal dis
`claimer.
`
`(*) Notice:
`
`(21) Appl. No.: 09/293,540
`(22) Filed:
`Apr. 16, 1999
`(51)
`... H04Q 7/20, H04B 7/185
`(52)
`455/522; 455/13.4; 370/318
`(58) Field of Search .............................. 455/68, 69, 70,
`455/522, 127, 13.4; 370/342, 318,320,
`468; 375/244, 312,329, 330, 308
`
`(56)
`
`References Cited
`U.S. PATENT DOCUMENTS
`
`... 370/342
`5,107,487 A * 4/1992 Vilmur et al. .......
`5,883,899 A * 3/1999 Dahlman et al. ........... 370/468
`5,982,760 A 11/1999 Chen .......................... 455/522
`
`6,034,952 A * 3/2000 Dohi et al. ................. 455/522
`6,081,727 A
`6/2000 Kondo ....................... 455/522
`6,128,506 A * 10/2000 Knutsson et al. ........... 455/522
`6,151,508 A 11/2000 Kim et al. .................. 455/522
`6,163,707 A 12/2000 Miller ........................ 455/522
`6,233,439 B1
`5/2001 Jalali .......................... 455/522
`6,295.289 B1 * 9/2001 Ionescu et al. ............. 455/522
`6,311,070 B1 * 10/2001 Tong et al. ................. 455/522
`* cited by examiner
`Primary Examiner Tracy Legree
`(74) Attorney, Agent, or Firm-Bruce Garlick
`(57)
`ABSTRACT
`The invention provides a System and method for controlling
`transmission power of a mobile unit in a wireleSS commu
`nication System which minimizes transmission power over
`shoot caused by counteracting the effects of deep fading.
`Sets of power control bits are transmitted from the base
`station to the mobile unit using L/4 DQPSK modulation. A
`first set of the bits indicates to the mobile unit a request to
`increase the mobile units transmission power by a predeter
`mined amount. A Second Set of the bits indicates to the
`mobile unit that the mobile unit should increase its trans
`mission power by an amount which is greater than the
`predetermined amount. A third set of the bits indicates to the
`mobile unit a request to decrease the mobile units transmis
`Sion power by the predetermined amount. A fourth Set of the
`bits indicates to the mobile unit that the mobile unit should
`decrease its transmission power by the amount which is
`greater than the predetermined amount.
`23 Claims, 4 Drawing Sheets
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`U.S. Patent
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`US 6,529,741 B1
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`U.S. Patent
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`Mar.4, 2003
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`Sheet 3 of 4
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`US 6,529,741 B1
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`(PriorArt) FIG.3a
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`U.S. Patent
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`Sheet 4 of 4
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`US 6,529,741 B1
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`1
`MULTI-BIT POWER CONTROLAND POWER
`CONTROL COMMAND SUB-CHANNEL
`DESIGN
`
`CROSS-REFERENCE TO RELATED
`APPLICATION
`The present application claims priority pursuant to 35
`U.S.C. Sec. 120 to U.S. patent application Ser. No. 09/273,
`411, filed Mar. 22, 1999, now issued as U.S. Pat. No.
`6,311,070, which is hereby incorporated herein by reference
`in its entirety.
`FIELD OF THE INVENTION
`This invention relates generally to the field of wireless
`communications Systems and more particularly to transmit
`ting power control bits over a Differential Quadriture Phase
`Shift Keying (DQPSK) modulated sub-channel and varying
`the Step size of power control to protect against transmit
`power overshoot in Code Division Multiple Access
`(CDMA) communications systems.
`BACKGROUND OF THE INVENTION
`In CDMA communications Systems, maximum uplink
`capacity is achieved when the power level of Signals
`received by the Base Transceiver Subsystem (BTS) is the
`same for all mobile users. Such a power level is called the
`“nominal power level.” If this nominal power level is
`maintained regardless of the distance between the base
`Station and the mobile unit and regardless of the Signal
`propagation environment then maximum uplink capacity is
`maintained.
`If the power level of a signal received from a mobile unit
`drops below the nominal level, the error probability for that
`user increases. If the power level of a Signal received from
`a mobile unit exceeds the nominal level, the probability that
`the signal will interfere with signals from other mobile units
`increases. Thus transmission power deviations from the
`nominal power level decrease the capacity of the System.
`Rayleigh fading is a problem which introduces a fast
`power deviation from the nominal power level and thus
`degrades System capacity.
`In current Third Generation Partner Project (3GPP)
`Systems, power control mechanisms are being employed
`which attempt to equalize the received power of the Signal
`from the mobile unit and to compensate for fast power
`deviations from the nominal power level caused by the
`impact of Rayleigh fading.
`The overall uplink power control for 3GPP is shown in
`FIG. 1. The BTS employs a Rake receiver to receive and
`demodulate a desired signal. It then determines a signal to
`noise ratio (SNR) of the received signal using SNR estima
`tion. The BTS then compares the determined SNR to the
`nominal power level to generate a power control bit (PCB).
`Typically power control is only concerned with a single bit
`wherein a 1 indicates to the mobile unit to increase trans
`mission power and a 0 indicates to the mobile unit to
`decrease transmission power. The PCB is multiplexed with
`data and transmitted to the mobile unit as a Transmit Power
`Control (TPC) signal (FIG. 2). The mobile unit receives the
`TPC signal, demodulates it, and separates the PCB
`(demultiplexes it). The mobile unit then converts the PCB to
`a power transmission gain (positive or negative) of the
`output power in the Extract PCB and Convert to Power Step
`Size block. This is considered closed loop power control.
`There are also methods in 3GPP considered outer loop
`power control. In outer loop power control systems, the BTS
`
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`adjusts the nominal power level based upon a Frame Error
`Rate (FER) probability for a particular nominal power level.
`The BTS measures the FER probability and determines a
`SNR threshold. If at the output of the Viterbi decoder, the
`FER is high, the nominal power level is increased. If the
`FER is low, the nominal power level is decreased. A system
`may employ one or both of these two methods.
`Channel fading without power control leads to a Standard
`deviation of 5.5 dB for all fading frequencies. However, due
`to deep fades of a desired signal, the Standard deviation may
`decrease more than 20 dB with respect to the required signal
`level. This leads to the increase of the error probability for
`a particular mobile unit.
`Based on the current 3GPP specification, closed loop
`power control results in a considerable reduction of SNR
`deviation for Small fading frequencies (e.g. in the range of
`8–15 Hz). However, the efficiency is greatly decreased when
`the fading frequency is above 30 Hz. This is because of the
`conventional fixed power control steps of 0.25 dB, 0.5 dB
`and/or 1 dB and the delay (at least one slot of power control
`bit command) which are not able to track the changes of the
`Signal power in the channel in fast fading environments. For
`the same reasons large power overshooting (i.e. too many
`increases or decreases to the transmission power in the
`mobile unit) occurs at the BTS input for all fading frequen
`
`CCS.
`Conventional 3GPP systems operate with a fixed power
`control step size (e.g. 1 dB) and a fixed power control
`command transmission delay. When a signal from a mobile
`unit experiences a deep fade, the BTS Sends consecutive
`power increasing commands to the mobile unit. The mobile
`unit receives these commands and increases its transmission
`power to compensate for the deep fading. However the
`mobile unit continues to increase its power even after the
`deep fade period ends, due to the power control command
`transmission delay. This continued increase in power causes
`the power overshoot (see FIG. 2). Power overshooting
`negatively impacts the uplink power control performance by
`increasing the Standard deviation of power control for the
`particular mobile unit and increasing the Overall interference
`experienced by transmissions to the BTS. Power overshoot
`ing has been observed to be as high as 5 dB and has been
`known to occur at all fading frequencies.
`One attempted solution to this problem has been to
`modulate the amplitude of the PCB. A larger than usual PCB
`amplitude would indicate a larger than usual Step size for
`increasing or decreasing the transmission power of the
`mobile unit while a smaller than usual PCB amplitude would
`indicate a smaller than usual step size. (See FIGS. 3a and
`3b). The step size is directly proportional to the amplitude.
`However, accurate detection of the amplitude modulated
`PCB is difficult and unreliable due to the nature of the
`channel (i.e. noise).
`Accordingly, there exists a need for a more reliable power
`control System which minimizes power overshoot.
`There also exists a need for a power control System which
`maximizes uplink capacity.
`There exists a need for a power control System which
`minimizes Standard deviation from the nominal power level.
`Accordingly, it is an object of the present invention to
`provide a more reliable power control System which mini
`mizes power overshoot.
`It is another object of the invention to provide a power
`control System which minimizes the Standard deviation from
`the nominal power level.
`It is still another object of the invention to provide a
`power control System which employs a variable Step size.
`
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`US 6,529,741 B1
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`These and other objects of the invention will become
`apparent to those skilled in the art from the following
`description thereof.
`SUMMARY OF THE INVENTION
`In accordance with the teachings of the present invention,
`these and other objects may be accomplished by the present
`invention, which provides transmission power control of a
`mobile unit in a wireleSS communication System.
`An embodiment of the invention provides a method of
`controlling transmission power of a mobile unit in a wireleSS
`communication System which includes the mobile unit
`receiving a multiple power control bits. The mobile unit
`increases its transmission power by a predetermined amount
`in response to receipt of one Set of the power control bits,
`and increases its transmission power by an amount which is
`larger than the predetermined amount in response to receipt
`of another set of the power control bits.
`Another embodiment of the invention provides a method
`of controlling transmission power of a mobile unit including
`a base Station transmitting multiple power control bits. A
`first set of the plurality of power control bits indicates a
`request to increase a transmission power by a predetermined
`amount, and another Set of the power control bits indicates
`a request to increase the transmission power by an amount
`which is larger than the predetermined amount.
`In another embodiment of the invention, a System is
`provided for controlling transmission power of a mobile unit
`in a wireleSS communication System. The System includes a
`mobile unit which includes a module for receiving groups of
`power control bits. A first set of the plurality of power
`control bits indicates that the transmission power should be
`increased by a predetermined amount. Another Set of the
`power control bits indicates that the transmission power
`35
`should be increased by an amount which is greater than the
`predetermined amount. The System further includes a mod
`ule for increasing the transmission power by the predeter
`mined amount in response to receiving the first Set of power
`control bits and, a module for increasing the transmission
`power by the amount which is greater than the predeter
`mined amount in response to receiving the another Set of
`power control bits.
`In Still another embodiment, the invention provides an
`apparatus for controlling transmission power of a mobile
`unit in a wireleSS communication System which includes a
`receiver configured to receive groups of power control bits.
`It also includes a DOPSK detector connected to the receiver.
`The apparatus includes a demodulator connected to the
`receiver, a demultiplexor connected to the demodulator,
`configured to Separate the power control bits from the
`transmit power control Signals. The apparatus includes a
`processor connected to the demultiplexor, configured to
`determine if a set of power control bits indicates increasing
`the transmission power by a predetermined amount, increas
`ing the transmission power by an amount which is larger
`than the predetermined amount, decreasing the transmission
`power by the predetermined amount, or decreasing the
`transmission power by the amount which is greater than the
`predetermined amount.
`Another embodiment of the invention includes an appa
`ratus for controlling transmission power of a mobile unit in
`a wireleSS communication System including a base Station.
`the base Station includes a transmitter configured to transmit
`sets of power control bits. It also includes a DQPSK
`65
`modulator connected to the transmitter. A first Set of the
`power control bits indicates a request to increase the trans
`
`4
`mission power by a predetermined amount. A Second Set of
`the power control bits indicates a request to increase the
`transmission power by an amount which is greater than the
`predetermined amount. A third set of the power control bits
`indicates a request to decrease the transmission power by the
`predetermined amount and, a fourth Set of the power control
`bits indicates a request to decrease the transmission power
`by the amount which is greater than the predetermined
`amount.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`The invention will be more clearly understood by refer
`ence to the following detailed description of an exemplary
`embodiment in conjunction with the accompanying
`drawings, in which:
`FIG. 1 illustrates a conventional closed loop power con
`trol system employed by 3GPP systems;
`FIG. 2 illustrates deep fading and the resulting power
`overshoot in 3GPP Systems;
`FIG. 3a illustrates conventional transmission power con
`trol;
`FIG. 3b illustrates conventional transmission power con
`trol with amplitude modulated power control bits;
`FIG. 4a illustrates a graphical representation of Single
`power control bits transmitted over a Differential Quadriture
`Phase Shift Keying modulated Sub-channel; and
`FIG. 4b illustrates a graphical representation of two
`power control bits transmitted over a Differential Quadriture
`Phase Shift Keying modulated Sub-channel.
`DETAILED DESCRIPTION OF THE
`INVENTION
`The invention provides a System and method of power
`control in a CDMA communication system, which mini
`mizes power overshooting caused by deep fade compensa
`tion. The system employs a Differential Quadriture Phase
`Shift Keying (DQPSK) modulated Sub-channel for commu
`nicating power control bits (PCB). An advantage of DQPSK
`is that it is more reliable than the conventional TPC Sub
`channel and it allows multiple bits to be employed for power
`control.
`FIG. 4a illustrates a graphical representation of a single
`PCB communicated over a DOPSK modulated Sub-channel.
`This single bit may be employed to operate in the conven
`tional manner of controlling the transmission power of the
`mobile unit (i.e. a +1 indicates that the remote user should
`increase the transmission power by a particular Step Size and
`a -1 indicates that the remote user should decrease the
`transmission power by the particular step size). It may also
`be employed in the manner disclosed in my copending
`patent application Ser. No. 09/273,411 which is hereby
`incorporated by reference.
`FIG. 4b illustrates that a second PCB can be employed to
`indicate that the remote user should increase or decrease the
`transmission power by a larger Step size. While only two bits
`will be discussed herein, it is possible to employ more than
`two bits to allow for additional step sizes. In a preferred
`embodiment, the particular step size is 0.25 dB and the
`larger step size is 1.5 dB. Those skilled in the art will
`recognize that these numbers are merely Set forth as exem
`plary (i.e. these are merely design choices) and that other
`step sizes may be employed for different results. Further, the
`ratio of the Step sizes (i.e. 6 to 1) may also be changed to Suit
`a particular System.
`The following rules may be employed to determine which
`Step size the base Station will request.
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`S
`Set two threshold values for the system such that: Thresh
`old 1 is the out-loop power control target QoS and Threshold
`2 is the instant Signal to Interference Ratio (SIR) (the
`preferred but not required value of Threshold 2 is 2 dB).
`If SIR-Threshold 1 and SIR-Threshold 1+Threshold 2
`then increase transmission power by AP
`If SIR-Threshold 1 and SIR-Threshold 1+Threshold 2
`then increase transmission power by AP
`If SIR-Threshold 1 and SIR-Threshold 1-Threshold 2
`then decrease transmission power by AP
`If SIR-Threshold 1 and SIR-Threshold 1-Threshold 2
`then decrease transmission power by AP2.
`The base Station may communicate this information to the
`remote unit as shown in the following table:
`
`One Step Size
`{I.Qbbo
`+1, +1
`-1, -1
`
`Increase by AP
`Decrease by AP1
`
`Two Step Size
`{I.Qbbo
`+1, +1
`-1, -1
`-1, +1
`+1, -1
`
`Increase by AP
`Decrease by AP
`Increase by AP,
`Decrease by AP,
`
`Those skilled in the art will recognize that while each bit has
`been provided with a specific meaning (i.e. +1+1 increase by
`AP,31 1, +1 increase by AP, etc.) a System could be
`designed which rearranges the definitions associated with
`the different bits (i.e. +1+1 increase by AP2, -1, +1 increase
`by AP, or any other rearrangement of the meanings) and
`still fall within the scope of the invention.
`The invention preferably employs L/4 DQPSK modula
`tion (although other forms of modulation could be
`employed). The System also employs the following equa
`tions for transmitting the TPCs.
`I=l cosAd(bo, b)-Q sinAdd(bo, b)
`Q=l sinAdd(bo, b)H-Q cosAdd(bo, b)
`where: k=time, bo, b are the TPC bits and
`
`bo
`
`1.
`O
`1.
`O
`
`b1
`
`1.
`1.
`O
`O
`
`ACD
`
`-3JIf4
`3J/4
`J/4
`-JIf4
`
`The invention may employ the circuit illustrated in FIG.
`1 with the addition of a DOPSK modulator in the base
`station transmitter and a DOPSK detector and modulator in
`the mobile units receiver. One or more of the elements of
`FIG. 1 could be realized as the same or different micropro
`ceSSorS or as Some other device Such as an application
`Specific integrated circuit (ASIC), programmable logic array
`(PLA), or another suitable logic device. They can also be
`realized in Software.
`While the invention has been described with respect to a
`particular rule base, other rules can be applied to achieve
`Similar results. For example, the number of thresholds may
`be changed, the rules may be based upon Some other Quality
`of Service (QoS) indication other than SIR, and/or the
`requirements for employing the larger Step size may be
`increased or decreased for varying results.
`It will thus be seen that the invention efficiently attains the
`objects Set forth above, among those made apparent from the
`
`6
`preceding description. In particular, the invention provides
`methods and apparatus for transmitting power control bits
`for adjusting the transmission power of a mobile unit based
`thereon to minimize power overshoot. Those skilled in the
`art will appreciate that the configuration depicted in FIGS.
`1 and 4 provides Such features.
`It will be understood that changes may be made in the
`above construction and in the foregoing Sequences of opera
`tion without departing from the Scope of the invention. It is
`accordingly intended that all matter contained in the above
`description or shown in the accompanying drawings be
`interpreted as illustrative rather than in a limiting Sense.
`It is also to be understood that the following claims are
`intended to cover all of the generic and Specific features of
`the invention as described herein, and all Statements of the
`Scope of the invention which, as a matter of language, might
`be said to fall therebetween.
`Having described the invention, what is claimed as new
`and secured by Letters Patent is:
`1. A method of controlling transmission power of a mobile
`unit in a wireleSS communication System comprising:
`Said mobile unit receiving a plurality of power control
`bits;
`Said mobile unit increasing a transmission power by a
`predetermined amount in response to receipt of one Set
`of Said plurality of power control bits, and
`Said mobile unit increasing Said transmission power by an
`amount which is larger than Said predetermined amount
`in response to receipt of another Set of Said plurality of
`power control bits.
`2. A method of controlling transmission power of a mobile
`unit according to claim 1 wherein Said one set of Said
`plurality of power control bits comprises two bits and Said
`another set of Said plurality of power control bits comprises
`two bits.
`3. A method of controlling transmission power of a mobile
`unit according to claim 2 wherein Said predetermined
`amount comprises 0.25 dB and wherein said amount which
`is larger than Said predetermined amount comprises 1.5 dB.
`4. A method of controlling transmission power of a mobile
`unit according to claim 1 further comprising:
`Said mobile unit decreasing Said transmission power by
`Said predetermined amount in response to receipt of a
`third set of said plurality of power control bits, and
`Said mobile unit decreasing Said transmission power by
`Said amount which is larger than Said predetermined
`amount in response to receipt of a fourth Set of Said
`plurality of power control bits.
`5. A method of controlling transmission power of a mobile
`unit according to claim 1 wherein Said plurality of power
`control bits are received over a Differential Quadriture Phase
`Shift Keying modulated sub-channel.
`6. A method of controlling transmission power of a mobile
`unit comprising:
`a base Station transmitting a plurality of power control
`bits;
`wherein a first set of said plurality of power control bits
`indicates a request to increase a transmission power by
`a predetermined amount, and
`wherein another set of said plurality of power control bits
`indicates a request to increase a transmission power by
`an amount which is larger than Said predetermined
`amount.
`7. A method of controlling transmission power of a mobile
`unit according to claim 6
`wherein a third set of said plurality of power control bits
`indicates a request to decrease Said transmission power
`by Said predetermined amount, and
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`7
`wherein a fourth set of said plurality of power control bits
`indicates a request to decrease Said transmission power
`by Said amount which is larger than Said predetermined
`amount.
`8. A method of controlling transmission power of a mobile
`unit according to claim 7 wherein Said predetermined
`amount comprises 0.25 dB and wherein said amount which
`is larger than Said predetermined amount comprises 1.5 dB.
`9. A method of controlling transmission power of a mobile
`unit according to claim 6 further comprising:
`said base station employing Differential Quadriture Phase
`Shift Keying modulation to transmit said plurality of
`power control bits.
`10. A method of controlling transmission power of a
`mobile unit according to claim 6 wherein each of Said Sets
`of Said plurality of power control bits comprises two bits.
`11. A System for controlling transmission power of a
`mobile unit in a wireleSS communication System compris
`ing:
`a mobile unit including:
`means for receiving a plurality of power control bits,
`wherein a set of said plurality of power control bits
`indicates that the transmission power should be
`increased by a predetermined amount, and wherein
`another Set of Said plurality of power control bits
`indicates that the transmission power should be
`increased by an amount which is greater than Said
`predetermined amount;
`means for increasing the transmission power by Said
`predetermined amount in response to receiving Said
`Set of Said plurality of power control bits, and,
`means for increasing the transmission power by Said
`amount which is greater than Said predetermined
`amount in response to receiving said another set of
`Said plurality of power control bits.
`12. A System for controlling transmission power of a
`mobile unit according to claim 11 wherein a third set of Said
`plurality of power control bits indicates that the transmission
`power should be decreased by Said predetermined amount,
`wherein a fourth set of said plurality of power control bits
`indicates that the transmission power should be decreased by
`Said amount which is greater than Said predetermined
`amount; and wherein Said mobile unit further includes:
`means for decreasing the transmission power by Said
`predetermined amount in response to receiving Said
`third set of Said plurality of power control bits, and,
`means for decreasing the transmission power by Said
`amount which is greater than Said predetermined
`amount in response to receiving Said fourth Set of Said
`plurality of power control bits.
`13. A System for controlling transmission power of a
`mobile unit according to claim 11, Said mobile unit further
`comprising a Differential Quadriture Phase Shift Keying
`detector coupled to Said means for receiving.
`14. An apparatus for controlling transmission power of a
`mobile unit in a wireleSS communication System compris
`ing:
`a receiver configured to receive a plurality of power
`control bits;
`a Differential Quadriture Phase Shift Keying detector
`coupled to Said receiver;
`a demodulator coupled to Said receiver;
`a demultiplexor coupled to Said demodulator, configured
`to Separate a plurality of power control bits from Said
`transmit power control Signals,
`a processor coupled to Said demultiplexor, configured to
`determine if a set of power control bits indicates one of
`
`15
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`25
`
`35
`
`40
`
`45
`
`50
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`55
`
`60
`
`65
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`8
`increasing the transmission power by a predetermined
`amount, increasing the transmission power by an
`amount which is larger than Said predetermined
`amount, decreasing the transmission power by Said
`predetermined amount, and decreasing the transmis
`Sion power by Said amount which is greater than Said
`predetermined amount.
`15. An apparatus according to claim 14 wherein Said
`processor is further configured to:
`increase the transmission power by Said predetermined
`amount if it determines that Said Set of power control
`bits indicates a request to increase the transmission
`power by Said predetermined amount;
`increase the transmission power by Said amount which is
`greater than Said predetermined amount if it determines
`that Said Set of power control bits indicates a request to
`increase the transmission power by Said amount which
`is greater than Said predetermined amount;
`decrease the transmission power by Said predetermined
`amount if it determines that Said Set of power control
`bits indicates a request to decrease the transmission
`power by Said predetermined amount; and,
`decrease the transmission power by Said amount which is
`greater than Said predetermined amount if it determines
`that Said Set of power control bits indicates a request to
`decrease the transmission power by Said amount which
`is greater than Said predetermined amount.
`16. An apparatus for controlling transmission power of a
`mobile unit in a wireleSS communication System compris
`ing:
`a base Station including:
`a transmitter configured to transmit sets of a plurality of
`power control bits,
`a Differential Quadriture Phase Shift Keying modulator
`coupled to Said transmitter;
`wherein a first set of said plurality of power control bits
`indicates a request to increase the transmission
`power by a predetermined amount;
`wherein a Second Set of Said plurality of power control
`bits indicates a request to increase the transmission
`power by an amount which is greater than Said
`predetermined amount;
`wherein a third set of said plurality of power control
`bits indicates a request to decrease the transmission
`power by Said predetermined amount; and,
`wherein a fourth set of said plurality of power control
`bits indicates a request to decrease the transmission
`power by an amount which is greater than Said
`predetermined amount.
`17. An apparatus according to claim 16 wherein Said Sets
`of said plurality of power control bits each include two bits.
`18. An apparatus according to claim 16 wherein Said
`Differential Quadriture Phase Shift Keying modulator is
`configured to modulate Said plurality of power control bits
`using L/4 Differential Quadriture Phase Shift Keying modu
`lation.
`19. wireless mobile unit comprising:
`an antenna,
`a receiver coupled to the antenna and configured to
`receive a plurality of power control bits,
`a transmitter coupled to the antenna;
`wherein the mobile unit is capable of increasing the
`transmit power of the transmitter by a predetermined
`amount in response to receipt of one set of the plurality
`of power control bits, and
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`Ex.1007 / Page 9 of 10Ex.1007 / Page 9 of 10
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`TESLA, INC.TESLA, INC.
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`US 6,529,741 B1
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`9
`wherein the mobile unit is capable of increasing the
`transmit power of the transmitter by an amount that is
`larger than the predetermined amount in response to
`receipt of another Set of the plurality of power control
`bits.
`20. The wireless mobile unit of claim 19, wherein:
`Said one Set of the plurality of power control bits com
`prises two bits, and
`said another set of the plurality of power control bits
`comprises two bits.
`21. The wireless mobile unit of claim 20, wherein:
`the predetermined amount is 0.25 dB; and
`the amount that is larger than the predetermined amount
`is 1.5 dB.
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`10
`22. The wireless mobile unit of claim 19, wherein:
`the wireleSS mobile unit is capable of decreasing the
`transmit power of the transmitter by the predetermined
`amount in response to a third Set of the plurality of
`power control bits, and
`the wireleSS mobile unit is capable of decreasing the
`transmit power of the transmitter by the amount that is
`larger than the predetermined amount in response to a
`fourth set of the plurality of power control bits.
`23. The wireless mobile unit of claim 19, wherein the
`plurality of power control bits are received over a Differ
`ential Quadrature Phase Shift Keying modulated Sub
`channel.
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`Ex.1007 / Page 10 of 10Ex.1007 / Page 10 of 10
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`TESLA, INC.TESLA, INC.
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