United States Patent (19)
`Irvin
`
`US006029074A
`Patent Number:
`11
`(45) Date of Patent:
`
`6,029,074
`*Feb. 22, 2000
`
`54). HAND-HELD CELLULAR TELEPHONE
`WITH POWER MANAGEMENT FEATURES
`
`75 Inventor: David Rand Irvin, Raleigh, N.C.
`73 ASSignee: Ericsson, Inc., Research Triangle Park,
`
`*
`
`Notice:
`
`This patent issued on a continued pros-
`ecution application filed under 37 CFR
`1.53(d), and is subject to the twenty year
`patent term provisions of 35 U.S.C.
`154(a)(2).
`
`21 Appl. No.: 08/850,913
`
`FOREIGN PATENT DOCUMENTS
`O 331 435 A2 of 1989 Japan.
`WO 93/O1659 of 1993 WIPO.
`WO 96/34461 of 1996 WIPO.
`OTHER PUBLICATIONS
`Pratt, Richard E. and Fitzgibbons, Thomas; “RF Power
`Configuration Method for Battery Equipped Portable
`Radios;” Motorola; vol. 24; Mar. 1995; pp. 75,77.
`“The
`GSM System;
`Radio Resource Management;
`1993;pp. 342–346.
`
`Primary Examiner Lee Nguyen
`Attorney, Agent, or Firm-Coats & Bennett, PLLC
`
`7
`
`51 Int. Cl. ............................................ "..., H04B 140 A mobile terminal includes power control logic which limits
`52 U.S. Cl. ............................ 455/571; 455/69; 455/127;
`the maximum transmit power of the mobile radio telephone
`455/522
`to conserve battery power when it is operated in a hand-held
`58 Field of Search .............................. 455/522, 69,569,
`mode. The mobile radio telephone includes power control
`455/571,572, 573, 574, 115, 116, 126,
`logic which Sets the transmit power in response to power
`127
`control codes received from a base Station. The power
`control codes transmitted from the base Station correspond
`to designated power levels. A signal is generated to indicate
`whether the mobile radio telephone is operated in a hand
`held mode. When the mobile radio telephone is operated in
`a hand-held mode, the power control logic Sets the power
`level at a maximum hand-held power level which is less than
`the maximum transmit power level
`o
`9 Claims, 6 Drawing Sheets
`
`56)
`
`References Cited
`U.S. PATENT DOCUMENTS
`1/1987 Mitzlaff.
`4,636,741
`... 455/126
`4,709,404 11/1987 Tamura et al. ...
`... 455/571
`5,146,614 9/1992 Furuno .........
`5,303.395 4/1994 Dayani .................................... 455/127
`5,457,814 10/1995 Myrskog et al..
`5,497.507 3/1996 Komaki.
`
`3O
`
`38
`
`24
`
`
`
`
`
`Power
`Control
`
`PA
`PA
`
`32
`
`
`
`
`
`Audio
`Processing
`
`44
`
`Control &
`Signalling
`Unit
`12
`
`
`
`
`
`
`
`
`
`
`
`
`
`14
`
`
`
`Charge
`indicator
`
`40
`
`18
`
`20
`
`A2
`
`1
`
`LG 1019
`
`

`

`Feb. 22, 2000
`2
`
`U.S. Patent
`wPS.
`
`.PmmUon
`
`
`
`
`
`bI
`
`mmH.
`m>0mEgon.
`
`mE2..
`
`89
`mm
`
`
`
`
`
` 3WWmEmwmuEn.m.S.92%VP.2,vn
`
`w63:00
`
`e
`Sheet 1 of 6
`6M
`
`6,029,074
`6,029,074
`
`uw
`mE5S3:23
`
`
`.
`
`3.
`
`
`
`5:365E@9ch>m_qw_ocan—>3._
`
`F959;
`
`we82,
`
`3
`
`E
`
`2
`
`
`
`

`

`U.S. Patent
`
`Feb. 22, 2000
`
`Sheet 2 of 6
`
`6,029,074
`
`Receive
`MAC
`
`Adjust power
`aCCOrding
`to MAC
`
`
`
`200
`
`202
`
`206
`
`
`
`POWer inhibit
`flag = 1
`
`208
`
`Revise MAC
`= 010
`
`Figure 2
`
`3
`
`

`

`U.S. Patent
`
`Feb. 22, 2000
`
`Sheet 3 of 6
`
`6,029,074
`
`300
`
`Receive
`
`MAC
`
`
`
`POWer inhibit
`flag = 1
`
`306
`
`
`
`
`
`
`
`
`
`304
`
`Adjust power
`according
`to MAC
`
`
`
`MAC E OOO
`O
`OO1
`
`Revise MAC
`= 010
`
`310
`
`Figure 3A
`
`4
`
`

`

`U.S. Patent
`
`Feb. 22, 2000
`
`Sheet 4 of 6
`
`6,029,074
`
`322
`
`MAC =
`OOO,001,010,
`011 or 100
`
`Rewise
`MAC 101
`
`MAC =
`000,001
`or 010
`
`Revise
`MAC = 011
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`000,001,010,
`or 011
`
`Revise
`MAC E 100
`
`Figure 3B
`
`5
`
`

`

`U.S. Patent
`
`Feb. 22, 2000
`
`Sheet S of 6
`
`6,029,074
`
`Receive
`
`MAC
`
`Power inhibit
`flag = 1
`
`400
`
`402
`
`
`
`406
`
`
`
`
`
`
`
`
`
`404
`
`Adjust power
`acCording
`to MAC
`
`MAC = 000
`O
`OO1
`
`
`
`Revise MAC
`= 010
`
`410
`
`Figure 4A
`
`6
`
`

`

`U.S. Patent
`
`Feb. 22, 2000
`
`Sheet 6 of 6
`
`6,029,074
`
`422
`
`MAC =
`000,001,010,
`011 or 100
`
`Revise
`MAC 101
`
`MACE
`000,001
`or 010
`
`Revise
`MAC = 011
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`000,001,010,
`or 011
`
`Revise
`MAC 100
`
`Figure 4B
`
`7
`
`

`

`6,029,074
`
`1
`HAND-HELD CELLULAR TELEPHONE
`WITH POWER MANAGEMENT FEATURES
`
`FIELD OF THE INVENTION
`The present invention relates generally to the field of
`mobile radio communication devices and more particularly
`to a method and apparatus for controlling the transmit power
`level in a mobile communication device.
`
`5
`
`2
`power generally within the aforementioned constraints on
`energy draw and interference. These Solutions are called
`here the external booster, the high-powered terminal, and the
`power-exception terminal.
`The external booster provides a second (external to the
`terminal) RF power amplifier and associated control cir
`cuitry as part of the hands-free cradle. When the hand-held
`terminal is captured by the cradle, its presence activates the
`second power amplifier (PA), which is inserted between the
`hand-held terminal and an external antenna. In practice, the
`power output level of the hand-held terminal itself is some
`times reduced upon insertion into the cradle So as not to
`overdrive the second PA. Together, the handheld terminal
`and the external booster work as a Class-I device within the
`cellular system. The second PA boosts the maximum RF
`power output typically to 3.0 Watts, thereby providing about
`7 dB advantage over a 0.6 Watt hand-held terminal in deep
`fringe operation. In order to provide this advantage,
`however, the mobile unit incurs considerable expense, bulk,
`complexity, and duplication of resources. For example, U.S.
`Pat. No. 5,457,814, “Power boost system for cellular
`telephone,” describes an external booster comprising two
`duplexers, an RF power amplifier, a fault detector,
`automatic-power control circuitry, and pulse-width modula
`tion circuitry that provides a way of communicating control
`information between the booster and the hand-held terminal.
`The Second Solution proposed by the prior art, called here
`the high-powered terminal, is taught in U.S. Pat. No. 4,636,
`741, “Multi-level power amplifying circuitry for portable
`radio transceivers,” wherein a hand-held unit with an inter
`nal high-power PA Senses its own insertion into a vehicle
`cradle, increases its status from Class-3 to Class-1 (3 Watts
`in the preferred embodiment), and re-registers itself with the
`cellular system under Station Class Mark 1. However, this
`Solution has Several drawbacks, including the need for a
`higher DC Supply Voltage to Sustain the high demands of the
`power amplifier (PA) when operating in Class-I service, the
`need for different construction to accommodate the thermal
`demands of Class-I operation not normally encountered in
`Class-3 operation, and the added complexity needed to
`change the Station Class Mark between Class-3 and Class-1.
`For these reasons, a later U.S. Pat. No. 5,457,814, teaches
`against the high-powered terminal of the type disclosed in
`4,636,741, noting that the approach leads to “increased
`weight, bulk and cost, and greatly diminishes the amplifier
`reliability of the radiotelephone.”
`A third Solution, called here the power-exception
`terminal, is disclosed in U.S. patent application Ser. No.
`08/728,681 filed Oct. 9, 1996 titled “RF Gain Enhancement
`for Cellular Telephone.” This application describes a coop
`erative relationship between a vehicle's cradle and a Class-3
`hand-held terminal. Upon insertion into the cradle, the
`terminal increases its power to the maximum level it can
`Sustain within Class-3 operation, and disables its power
`control apparatus. Although this Solution has the great Virtue
`of Simplicity, it provides no increase in transmitter power
`over that which the Class-3 terminal has inherently within its
`grasp, and it incurs the risk, although perhaps slight, of
`creating undue interference with other radio links whenever
`its power-control apparatus is disabled.
`In view of the limitations of the prior art as described
`above, there remains a need for a simple, inexpensive
`hand-held terminal that provides increased transmitter
`power to give better Service indoors or in fringe areas,
`wherein the increased transmitter power is enabled when the
`terminal is inserted into a docking Station used to provide an
`RF link in Support of a portable computer, or into a vehicle's
`
`BACKGROUND
`The range of a radio communication link, for example the
`radio link used to connect a hand-held cellular telephone to
`a cellular base Station, depends on a number of factors.
`Among these are receiver Sensitivity at the base Station,
`antenna gain at the receiver and transmitter, path loSS, and
`RF transmitter power at the hand-held terminal. In general,
`a more powerful hand-held terminal will have greater capa
`bility to provide Service within Shielding Structures Such as
`buildings and to Sustain conversations deeper into fringe
`CS.
`Nevertheless, the advantages of having a powerful termi
`nal are counterbalanced by a number of practical consider
`ations that limit the amount of power usefully disposed to a
`hand-held terminal. Primary among these considerations are
`the need to conserve the draw of electrical energy from the
`terminal's Small rechargeable battery, and the need to
`throttle power to the lowest useable level so as to avoid
`interference with other radio linkS active at the same time.
`Under certain conditions, however, the need to limit
`power is relaxed, for example or when the cellular terminal
`is used in a home docking Station to provide data, Voice, or
`Security-system-backup communications, or when the cel
`lular terminal is operated with a hands-free cradle in a motor
`vehicle. In these and Similar applications, the docking Sta
`tion or cradle makes external power available, often by way
`of an integral battery charger, thereby easing the battery
`draw constraint. In both cases, however, the need remains to
`throttle power as appropriate to avoid unnecessary interfer
`CCC.
`In order to minimize interference, a cellular base Station
`measures the Strength of the incoming Signal it receives from
`the mobile unit, and instructs the mobile unit to adjust its
`radiated power to the lowest level adequate to Sustain good
`quality communications. This enables the mobile Station to
`maintain communications as it moves about and experiences
`variations in path loSS. The power adjustments ordered by
`the base Station must, of course, fall within the capability of
`the terminal to supply RF power, and must further fall within
`the practical constraints of energy draw.
`Within the accepted industry standards for cellular
`telephones, terminal power is generally categorized by class.
`For example, a terminal designed for operation with a GSM
`System falls into one of five classes, where those classes
`have maximum peak power-output limits ranging from 20
`Watts (Class 1) to 0.8 Watts (Class 5), and where the power
`adjustments commanded by the base Station take place over
`15 steps of 2 decibels (dB) each. Within the AMPS system
`used in North America and elsewhere, three classes are used
`which have a maximum transmit power of 6 dbW (Class 1),
`2 dbW (Class 2), and -2 dbW (Class 3). Because of battery
`limitations, handheld terminals ordinarily operate as Class-3
`devices. This unfavorably limits their capability to provide
`good quality Service within buildings and in deep-fringe
`areas. To overcome Such limitations when hand-held termi
`nals are used with hands-free accessory cradles in motor
`vehicles, the prior art teaches three Solutions to maximizing
`
`15
`
`25
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`8
`
`

`

`6,029,074
`
`3
`hands-free cradle, and yet wherein the terminal operates
`within known constraints imposed by battery capacity used
`as a hand-held device.
`
`SUMMARY OF THE INVENTION
`The present invention provides a mobile radio telephone
`which includes power control logic to limit the maximum
`transmit power of the mobile telephone when it is operated
`in a hand-held mode. The transmit power of the mobile
`terminal is Set in response to power control codes received
`from a base Station. In the preferred embodiment, the power
`control codes are mobile attenuation codes which corre
`spond to pre-defined power levels. The power levels include
`a maximum transmit power level and a plurality of lower
`power levels. When the mobile terminal is operated in a
`hand-held mode, one of the lower power levels is designated
`as the maximum hand-held transmit power level. Upon
`receipt of a mobile attenuation code from the base Station,
`the mobile terminal determines whether the unit is operating
`in a hand-held mode, and if So, whether the mobile attenu
`ation code calls for a power level greater than the maximum
`hand-held transmit power level. If both these conditions are
`met, the transmit power level is Set equal to the maximum
`hand-held transmit power level. In all other cases, the
`transmit power level is Set to the power level designated by
`the mobile attenuation code.
`In other embodiments, the power levels associated with
`the various mobile attenuation codes are optionally reduced
`for hand-held use by menu-driven user input or in automatic
`response to signals that indicate low battery reserves in order
`to prolong battery life at the expense of transmission range.
`
`DETAILED DESCRIPTION OF THE DRAWINGS
`FIG. 1 is a block diagram of a mobile terminal according
`to the present invention.
`FIG. 2 is a flow diagram of the power control logic for the
`mobile terminal.
`FIGS. 3A AND 3B are a flow diagram of the power
`control logic wherein the power cap is varied based on a
`Selection by a user.
`FIGS. 4A AND 4B are a flow diagram of the power
`control logic wherein the power cap is varied based on the
`state of the battery.
`DESCRIPTION OF THE INVENTION
`Referring now to the drawings, an improved hand-held
`mobile terminal according to the present invention is shown.
`The hand-held mobile terminal 10 is a fully functional,
`battery powered, mobile transceiver capable of Sending and
`receiving voice and/or data Signals. The hand-held mobile
`terminal 10 may also be inserted into a cradle in a vehicle or
`connected to a docking Station. The hand-held mobile ter
`minal 10 of the present invention is a Class 2 AMPS radio
`telephone. It will be appreciated, however, that the invention
`might also be advantageously used in Class 1 or other
`devices.
`The mobile terminal 10 includes a microprocessor 12 for
`controlling the operation of the mobile terminal 10 and a
`program memory 14 for Storing programs used by the
`mobile terminal 10. The microprocessor 12 is interfaced by
`a system bus 16 with a keypad 18, display 20, audio
`processing circuits 22, receiver 24, and transmitter 26. The
`keypad 18 and display 20 provide a user interface. The
`receiver 24 and transmitter 26 are coupled to an antenna 30
`by coupler 28 so as to permit fill duplex communication. The
`
`4
`audio processing circuit 22 provides basic analog audio
`outputs to a speaker 34 and accepts analog audio inputs from
`a microphone 32. Received signals picked up by the antenna
`30 are demodulated and decoded by the receiver 24. The
`transmitter 26 encodes and modulates Signals passed to it by
`the audio processing circuits 22. The output of the trans
`mitter 26 is amplified by a power amplifier 36 which is
`controlled by a power control unit 38. The power amplifier
`36 and power control unit 38 determine the power level at
`which the Signal is transmitted.
`The control and Signaling unit 12 performs most of the
`control functions of the radio telephone 10. One of these
`functions is power control. The control and Signaling unit 12
`controls the transmit power level of the mobile terminal 10
`in accordance with commands received from the base Sta
`tion. In the AMPS system used in North America, there are
`a total of 8 power levels. The base station determines the
`appropriate power level for the mobile terminal 10 based on
`Strength and quality measurements on the Signal received
`from the mobile telephone 10. The base station sends power
`control signals to the mobile terminal 10. The power control
`Signals are Sent via the slow ASSociated Content Channel
`(SACCH) or the Fast Associated Control Channel
`(FACCH). The control and signaling unit 12 then sets the
`transmit power level of the mobile terminal 10 based on the
`Signals received from the base Station.
`The power control Signals transmitted by the base Station
`to the mobile terminal 10 are in the form of a mobile
`attenuation code (MAC). Table 1 below sets forth the MAC
`and power associated with each power level in the AMPS
`system for Class I, II, and III devices.
`
`15
`
`25
`
`35
`
`Power
`
`Power For Class (in dbW
`
`Level
`
`MAC
`
`Class I
`
`Class II
`
`Class III
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`O
`1.
`2
`3
`4
`5
`6
`7
`
`OOO
`OO1
`O10
`O11
`1OO
`101
`110
`111
`
`6
`2
`-2
`-6
`-10
`-14
`-18
`-22
`
`2
`2
`-2
`-6
`-10
`-14
`-18
`-22
`
`-2
`-2
`-2
`-6
`-10
`-14
`-18
`-22
`
`-2 dbW=0.631. Watts; 2 dbW=1.58 Watts; 6 dbW=3.98
`Watts
`When the mobile terminal 10 receives a power control
`Signal from the base Station, it sends instructions to the
`power control module 38 to adjust the transmit power
`accordingly. The power control module 38 includes a Series
`of attenuators or other components for controlling the output
`of the power amplifier 36. The power amplifier 36 may be
`a single Stage amplifier or a multiple-stage amplifier. If a
`multiple Stage amplifier is used, the power control module
`38 could include multiple bias adjustments and attenuators
`for controlling the output in each Stage of the power ampli
`fier 36. There are a wide variety of power amplifiers and
`controls which could be used and which are well known to
`those skilled in the art Therefore, a detailed description of
`the power amplifier and power control is omitted.
`The hand-held terminal 10 includes power limiting logic
`to effectively limit the transmit power to a predetermined
`maximum hand-held power level when used as a hand-held
`device. In the preferred embodiment of the invention, the
`maximum hand-held power level is less than the maximum
`power level for Class 2 devices. More specifically, in the
`
`9
`
`

`

`6,029,074
`
`15
`
`25
`
`35
`
`40
`
`S
`preferred embodiment the MAC corresponding power level
`0 and power level 1 is revised downward when the mobile
`terminal 10 is used as a hand-held device to artificially limit
`the maximum transmit power. For example, when the MAC
`is equal to 000 or 001, it is changed to 010. As shown in
`Table 1, this limits the transmit power of the mobile terminal
`to -2db W. Where the mobile terminal 10 is inserted into a
`cradle of a vehicle or attached to a docking Station having an
`external power Source, the power level is adjusted according
`to the MAC for all values. Thus, for Class 2 devices, the
`mobile terminal 10 would have a maximum transmit power
`of 2 dbW when docked to a cradle or other docking station.
`FIG. 2 is a flow diagram showing the power control logic
`used by the mobile terminal 10. The terminal 10 awaits
`receipt of a mobile attenuation code (MAC). Upon its receipt
`(block 200), the MAC is compared with values 000 and 001
`(block 202), both of which correspond in the AMPS systems
`to the Class-2 RF power levels of +2 dbW (1.58 Watts). If
`the MAC has neither value 000 nor value 001, the power
`control logic adjusts power according to the MAC (block
`204).
`If the MAC has values 000 or 001, the power control logic
`checks the status of the power-inhibit flag (block 206),
`which indicates whether the terminal is operating as a
`hand-held device or as a captured device as explained below.
`If the power inhibit flag is set to zero, which indicates
`capture of the terminal by a docking Station or cradle, the
`power control logic adjusts RF power according to the
`MAC(block 204). If the power-inhibit flag is set to one,
`which indicates hand-held use, the MAC is revised from 000
`or 001 to 010 (block 208), and the power control logic
`adjusts power according to the revised MAC (block 204).
`The power-inhibit flag is set as follows. In the preferred
`embodiment, the presence of a docking Station (flag=0) is
`indicated by a data-communications clear-to Send Signal on
`the terminal's System bus. For this purpose, however, an
`equivalent signal can be provided by other recognized
`data-communication protocol signals, by a mechanical key
`indicating the terminal's capture by the docking Station, by
`the disablement of the terminals internal microphone, by
`the presence of an infrared link indicating the connection of
`the terminal with a portable or other computer, by means of
`an explicit Signal communicated to the terminal through its
`System bus, or by any number of equivalent indicators.
`Capture by a vehicle's hands-free cradle (flag=0) is indi
`cated in the preferred embodiment by the connection of an
`external antenna. For this purpose, however, an equivalent
`Signal can be provided by other indicatorS Such as a
`mechanical key indicating capture by a cradle, by the
`disablement of the terminals internal Speaker, by means of
`a signal communicated to the terminal through its System
`bus, or by any number of equivalent indicators. Hand-held
`Status is indicated by the absence of any signal that the
`terminal has been captured by a docking Station or cradle. In
`Such case, the power inhibit flag is Set equal to 1. Otherwise,
`the power inhibit flag is Set equal to 0.
`The power control logic can be modified to allow the user
`the option of Selecting a power cap to be observed when the
`mobile terminal is operated in a hand-held mode. The user
`can interact with the mobile terminal 10 using the keypad 18
`and display 20 to Select a power cap. In a preferred
`embodiment, the user can Select one of three power caps: A,
`B, and C. If option A is Selected, the terminal's power is
`capped by limiting the MAC to 011, which corresponds to
`-6 dbW or approximately 0.250 Watts. If option B is
`Selected, the terminal's power is capped by limiting the
`MAC to 100, which corresponds to -10 dbW or approxi
`
`45
`
`50
`
`55
`
`60
`
`65
`
`6
`mately 0.100 Watts. If option C is selected, the terminals
`power is capped by limiting the MAC to 101, which
`corresponds to -14 dbW or approximately 0.040 Watts. If no
`option is Selected, the hand-held power is limited to a default
`value of -2 db.W.
`FIGS. 3A and 3B show the power control logic for a
`mobile terminal having a user-Selectable power cap. The
`terminal waits for a MAC from the base station. When a
`MAC is received (block 300), the mobile terminal 10 checks
`the power inhibit flag (block 302). If the power inhibit flag
`is off (=0), the power level is adjusted according to the MAC
`(block 304). Otherwise the mobile terminal 10 determines
`whether the user has activated a power cap (block 306). If
`the power limit option is not Selected, the mobile terminal
`checks the value of the MAC (block 308) and revises the
`MAC if it has a value of 000 or 001 (block 310). If the MAC
`has a value other than 000 or 001, then the power level is
`adjusted according to the MAC (block 304).
`If the power limit option is activated, the mobile terminal
`10 determines the option selected (block 312) and then the
`program flow branches depending upon which option is
`Selected. After determining the option Selected, the mobile
`terminal 10 checks the value of the MAC (blocks 314,318,
`322). The MAC is revised for specified values (blocks 316,
`320, 324) and otherwise remains unchanged. The mobile
`terminal 10 then adjusts the power level according to the
`MAC (block 304).
`In another embodiment (FIGS. 4A and 4B), the basic
`process of FIG. 3 is adapted to optionally cap power
`according to the State of charge of the terminal's battery.
`Again, the user interacts through a menu to activate or
`deactivate this option. In this case, however, the further
`Selection of option A, B, or C is automatically coupled to a
`battery-charge indicator, for example to the Six-State indi
`cator provided by the Ericsson AH-310 cellular telephone
`terminal. In the illustrative example shown in FIG. 4, battery
`States B5 and B4 are logically coupled to power option A,
`battery states B3 and B2 are coupled to power option B, and
`battery states B1 and B0 are coupled to power option C.
`FIGS. 4A and 4B show the power control logic for a
`mobile terminal having a power cap logically coupled to the
`terminal's battery state. The terminal waits for a MAC from
`the base station. When a MAC is received (block 400), the
`mobile terminal 10 checks the power inhibit flag (block
`402). If the power inhibit flag is off (=0), the power level is
`adjusted according to the MAC (block 404). Otherwise the
`mobile terminal 10 determines whether the user has acti
`vated a power cap (block 406). If the power limit option is
`not activated, the mobile terminal checks the value of the
`MAC (block 408) and revises the MAC if it has a value of
`000 or 001 (block 410). If the MAC has a value other than
`000 or 001, then the power level is adjusted according to the
`MAC (block 404).
`If the power limit option is activated, the mobile terminal
`10 determines the state of the battery (block 412) and then
`checks the value ofthe MAC (blocks 414,418,422). The
`MAC is revised for specified values (blocks 416, 420, 424)
`and otherwise remains unchanged. The mobile terminal 10
`then adjusts the power level according to the MAC (lock
`404).
`What is claimed is:
`1. A method for controlling the transmit power in a radio
`mobile terminal having a power class rating comprising:
`a) establishing a plurality of power levels including a
`maximum transmit power level and a plurality of lower
`power levels,
`b) establishing a maximum hand-held power level which
`is less than Said maximum transmit power level for the
`present power class rating of the mobile terminal;
`
`10
`
`

`

`6,029,074
`
`7
`c) receiving a power command transmitted from a remote
`location at Said mobile terminal, wherein Said power
`command designates one of Said power levels to use
`during transmissions,
`d) generating a mode signal indicating whether the mobile
`terminal is operating in a hand-held mode,
`e) transmitting at the power level designated by said
`power command when the mode Signal indicates that
`the mobile terminal is not in a hand-held mode;
`f) transmitting at the designated power level when the
`mode Signal indicates that the mobile terminal is in the
`hand-held mode and the designated power level is leSS
`than or equal to the maximum hand-held power level;
`and
`g) transmitting at the maximum hand-held power level
`when the mode Signal indicates that the mobile terminal
`is in the hand-held mode and the designated power
`level is greater than the maximum hand-held power
`level without changing the power class rating.
`2. The power control method of claim 1 further including
`the Step of Selecting Said maximum hand-held power level
`by a user, and Storing Said Selection in Said mobile terminal.
`3. The power control method of claim 1 further including
`the Step of Setting the maximum hand-held power level
`based on the State of a battery used to power Said mobile
`terminal when operating in the hand-held mode.
`4. In a radio mobile terminal having a power class rating
`which adjusts its transmit power level according to power
`control codes transmitted to the mobile terminal from a base
`Station, a method for limiting transmit power when the
`mobile terminal is operated in a hand-held mode Said
`method comprising:
`a) generating a mode signal indicating whether the mobile
`terminal is operating in the hand-held mode,
`b) receiving said power control codes from Said base
`Station indicating one of a plurality of power levels,
`c) revising the power control code to indicate a maximum
`hand-held power level when the mobile terminal is in
`the hand-held mode and the power control code des
`ignates a power level greater than Said maximum
`hand-held power level; and
`d) transmitting a signal at a power level indicated by said
`revised power control code when the received power
`
`5
`
`15
`
`25
`
`35
`
`40
`
`8
`control code is greater than Said maximum hand-held
`power level and Said mobile terminal is in the hand
`held mode without changing the power class rating.
`5. The power control method of claim 4 further including
`the Step of Selecting Said maximum hand-held power level
`by a user, and Storing Said Selection in Said mobile terminal.
`6. The power control method according to claim 4 further
`including the Step of Setting the maximum hand-held power
`level based on the State of a battery used to power Said
`mobile terminal when operating in the hand-held mode.
`7. A mobile terminal which sets its transmit power level
`based on a power control code received from a base Station,
`Said mobile terminal comprising:
`a) a transmitter;
`b) a power amplifier coupled to said transmitter to pro
`duce an output signal at one of a plurality of power
`levels, wherein Said power levels include a maximum
`transmit power level and a plurality of lower power
`levels;
`c) means for generating a mode signal indicating whether
`Said mobile terminal is operating in a hand-held mode,
`d) power control logic coupled to said power amplifier
`and responsive to Said power control code and Said
`mode Signal for varying the transmit power level of
`Said mobile terminal without changing the power class
`rating, Said power control logic being operative to Set
`the transmit power level at a maximum hand-held
`transmit power level which is less than the maximum
`transmit power level for the present power class rating
`of said mobile terminal when (1) the mode signal
`indicates that the mobile terminal is in the hand-held
`mode, and (2) the power control code designates a
`power level greater than Said maximum hand-held
`power level.
`8. The mobile terminal according to claim 7 further
`including input means to enable a user to input Said maxi
`mum hand-held power level, and Storage means to Store Said
`maximum hand-held power level.
`9. The mobile terminal according to claim 7 further
`including a battery charge indicator, Said power control
`means being responsive to Said battery charge indicator to
`vary the maximum hand-held power level.
`
`k
`
`k
`
`k
`
`k
`
`k
`
`11
`
`