CA2086009C - Power control of a direct sequence cdma radio - Google Patents
Power control of a direct sequence cdma radioInfo
- Publication number
- CA2086009C CA2086009C CA002086009A CA2086009A CA2086009C CA 2086009 C CA2086009 C CA 2086009C CA 002086009 A CA002086009 A CA 002086009A CA 2086009 A CA2086009 A CA 2086009A CA 2086009 C CA2086009 C CA 2086009C
- Authority
- CA
- Canada
- Prior art keywords
- signal
- attenuation
- controllable
- generating
- coupled
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W52/00—Power management, e.g. TPC [Transmission Power Control], power saving or power classes
- H04W52/04—TPC
- H04W52/52—TPC using AGC [Automatic Gain Control] circuits or amplifiers
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03G—CONTROL OF AMPLIFICATION
- H03G3/00—Gain control in amplifiers or frequency changers without distortion of the input signal
- H03G3/20—Automatic control
- H03G3/30—Automatic control in amplifiers having semiconductor devices
- H03G3/3036—Automatic control in amplifiers having semiconductor devices in high-frequency amplifiers or in frequency-changers
- H03G3/3042—Automatic control in amplifiers having semiconductor devices in high-frequency amplifiers or in frequency-changers in modulators, frequency-changers, transmitters or power amplifiers
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04J—MULTIPLEX COMMUNICATION
- H04J13/00—Code division multiplex systems
Abstract
The power control apparatus of the present invention is comprised of a local oscillator signal path coupled to a mixer (106) through a variable attenuator (107) and an IF signal path coupled to the mixer (106) through two variable attenuators (108 and 109) coupled in series. The IF signal path atten-uators (108 and 109) are controlled by digital control circuitry (111) while the local oscillator path attenuator (107) is controlled by the control circuitry through a level shifter (110).
The power level of the signal generated by the mixing of these two signals is less than the conducted output of the radiotelephone's power amplifier.
The power level of the signal generated by the mixing of these two signals is less than the conducted output of the radiotelephone's power amplifier.
Description
~ - 1 -POWER CONTROL OF A DIRECT SEQUENCE CDMA
RADIO
Field of the Invention The present invention relates generally to the field of co~ --iç~*on~ and particularly to code-division multiple acces~ (CDMA) transmitter power control.
RnrL~ .oulld of the Invention Direct-sequence CDMA (DS-CDMA) type r~Aiotele-pbon~8 .c~ e some form of power m~n~gement 8~ h~me to control the output power level of the end user's radiotele-phone'~ tra~ ,er to control ~ale,n intelferc~,ce at the input of the base site l~ece;ver. DS-CDMA is e~l~ine~ in detail in John G. Proakis, Digital Communications, 2nd Edition, pages 800-845. Ihis power m~nagement~ performed by the comhin~
tion of the base station aceiver, base st~tion transmitter, and user radiotele~one (mobile)~ ~L~e~lts a transmitting ra-~iotelep~ne from using more of the system capacity than i~
n-~e-le l for adequate communication from the mobile to t_e base St~tiQ~
This power control is l,er~med by two power control loops, an open loop for the initial es~im~ts and a closed power control loop to correct this initial estim~te. The radiotele-phone, in pe.ror lling the open loop control, uses the ~eceived signal strength in~iic~tor (RSSI) to cstim~te the signal path power 1088 from the base to the radiotelephone. The radiotele-phone can then compens~te the amount of power loss when transmitting back to the basé station. Since the loss from the base station to the radiotelephone is not the same as the ra-diotele}!hone to the base station due to generally different and ~_ - 2 -witely separated transmit and receive frequencies, this is just an initial estim~te that must be co"e~led.
The co".:~:tion, which n~oAifies the original estim~te, is ~cco~npli~h~ by the base st~t;on transmitting power control S bits to the mobile radiot~lephone at typical rates of 800 to 1000 times per second A power bit of 1 instructs the radiotele-phone to increase power by one power step and a O instructs the radiotelephone to decrease power by one power step or vice versa depen~ling on an agreed upon 8,~leul protocol. One 10 power step is a set value typically in the range of 0.5 to 1.5 dB.
The closed loop control has a typical control range of ~24 dB.
The total power control range is typically 80 dB for a 1 watt m~iml1m power mobile.
A DS-CDMA ~-~iotelephone's power ~mplifier must be 15 at least class AB linear since the m~ A~ ti~- for the system may be par~y ~mplit~lAe m~lll~te~ for all mo~ ti~n types and also to control transmitter splatter after the ml~Alll~tiol~
ba"dwidth has been set by filters before the power ~mplifier.
As is already known by one ~ le~l in the art, the ouL~.lt of lin-20 ear power amplifiers have to be controlled by some form of in-line ~ttenlliqtion and not by controlling the power supply volt-age. This c~tlse~ a problem in systems, such as the D~
CDMA radiotelephone system, where the power control re-quired has a large range. This wide power control range can 25 result in spurious radiation out of the circuits at a higher level than the desired conducted r~Ai~tjr~n~ thus interfering vwith the desired level of the tr~n~mitted ~iEn~l~. This type of radiation is also ~liffic~lt to shield adequately to keep it from interfe~ing with other circuit~ in the radiotelephone.
30 Additionally, there i9 a problem with conducted le~lra~e around variable ~tPnll~tor circuit~ that control the RF output level. There is a resulting need for a circuit that ~cco.~ ishes the vanable attenuator filnctiQn without c~ ne the spurious r~Aistior~ or le~ ge problem~.
~_ - 3 -Sllmm~ry of the Invention The power control apparatus of the present invention is S c~ ..yl;sed of a local oscillS~tQr signal path coupled to a mixer through a variaUe S~ttenllSttQr and an Il? signal path coupled to the iser through two variable S~ttem~Sttors coupled in series. The Sltten~Sttors are controllet by digital control ~c~ . The miser generates a transmit frequency signal 10 from the mi~ing of the ~tt~nl~ste l IF signal and the ~ttenttS~tE 1 local oscillator ~ign~l.
Bnef Description of the Drawings FIG. 1 shows the power control apparatus of the present .~e.... .......................... ....lion with the rec~;~,e~ front end ant l~tter back end.
FIG. 2 shows a typical transmit power control circuit in accordance with the IJresc~lt invention.
FIG. 3 shows a srhem~tic diagram of the level shift block.
FIG. 4 shows the transfer ft~nctiQn of the level shift block.
Det~ileA Description of the I~efe~ed ~JmhoAimçnt The i- liot^lephone power control apparatus of the pre-sent invention ~e.~its attenuation of DS-CDMA ~iEn~l~ before tr~nsmi~siQn without spurious or conducted ,~ t;Qn prob 30 lems. This i8 r~c~npli~heA by distributing the attenuation to both inputs of the mLlcer that generates the transmit frequency signal and keeping the power level of this signal below the level of the transmitted ~ign~l, The power control apparatus of the present invention is 35 illustrated in FIG. 1. The power control portion of FIG. 1 in-cludes elçments (106) through (113). The ~ntenn~ (101) is used to ,ec¢;ve and transmit DS-CDMA ~ign~l~ with the range of +36 to -51 dBm being a typid t~.s it power control range.
The b~n~3r~s filters (102 and 103) are cQnnected in duplex f~hion to the transmitter output and the leCeiv~r input re-S s~e~l ively. The power ~mplifier (104) i~ at least a class AB lin-ear power ~mrlifier ~p~hle of providing the nscess~ y max-imum power and gain of the ~ign~l~ from the power conk aplJ~at~s which are filtered to the final transmitter fre-quency range by the b~n~s filter (105).
The power control a~,t)a-~tus is ~,;sed of dual paths to the miser (106); one path for the local oSç~ tQr signal and the other for the IF signal from the mod~ tQr section of the typical D~CDMA tran~lter. Both paths of the power con-trol ~atus have variable ~ttenl~tnrs that are controlled by 15 a tra~s~t.ter power control circuit (111) having a digital-t~
~n910~ (D/A) co~ e~ le~ and low pass filtering. Variable atten-uators (108) and (109) are cQnnected in senes bel~.~e.. the IF
signal and the miser (106). They are controlled by the ~tteml~-tor control signal (112) from the transmitter power control cir-20 cuit (111). A variable ~tt~nll~t~r (107) is in serie~ with the lo-cal os~ll~tor signal and the 3eCo-~l input to the miser. This ~tte~n~tor, in the p~efer~¢d emho~3im~nt is controlled by a signal derived from the ~ttsnl~tQr control signal (112) that is level ~hifte~l and delayed by a level shift circuit (110). The pre-25 ferred embo~limPnt of the power control ap~a.atus is imple-mented as an integrated circuit of the rliPlectrically isolated monolithic microwave integrated circuit (DIMMIC) or another high speed bipolar or bipolar-complementary metal o~ide se_iconductor (BICMOS) process. All of these types of 30 integrated circuits, be~ e they are very small, contribute lit-tle to spurious emiSsin-l~ that would int~.L~ with the desired range of power control.
It is also necessary to control signal le~k~ge from the IF
lead of the IC to the local oscillator lead of the IC. If the entire range of power control were to be ~CCG~ sh~l without the variable attenuator (107), the ;~01At;~r~ belween the two signal input leads woult have to be greater than the desired power control range. This problem is elimin~t~ l by the variable at-5 t~nl~qtQr (107) that re~lllces the dynamic range of the attenua-tion n~e~le~l in the IF branch, thus re~itt~ ing the necessAry lead i~ol~*on. At the mid or lower end of the dynamic range of the desired mi~er output there is no problem in reducing the level of the local oscillator sign~l. This has the effect of de-lO sensitizing the mixer and reducing its gain. At high desiredoutput signal levels, level shift circuit (110) is arranged so that changes in the ~Att~n-~AtQr cG,ltwl signal (112) have no effect on the vanable attenuator (107). The variable Atte~ t~r (107) i8 controlled by a signal (113) that is pro-l-~ e-l by the level shift lS circuit (110).
In the ~.efe.~e1 emho~ ent of the l"ee.,t i~lve~t ~n, the local o~llAt~r signal operates in the range of 939 - 964 MHz and the IF signal is (115) MHz. The miser (106) gener-ates a tr~ncmit frequency signal in the range of 824 - 849 MHz 20 at a power range of +11 to -75 dBm. This signal is bAn~lrA~s filtered (105) before the power Amrlifier (104). The power am-plifier (104) in.,.~--es the power level to +38 to -48 dBm. This signal i8 then bAn-lpA~s filtered (102) again before tr~n~mi~
sion from the An~n~ at a power level range of +35 to -51 25 dBm. It can be seen from these typical power levels that the tran~,l..iller frequency is first generated at a level below the tesired AntennA oul,~ut level. This is done by ~,erfoL~ng the needed vanable Attenl~*Qn by the cQ~nhinA~;Qn of variable at-tenllAtQrs in the IF and the local os~ tQr brA~n~ hes of the 30 mi~er (106). This guarantees thst spurious ~ ~;;A1;On of the transmit frequency will be below the desired and controlled con~ cte~l antenna output.
The Att~n-l~tQr control signal (112) for the power control al.l,a~ atus of the present invention can be performed by a transmit power control circuit such as is illustrated in FIG. 2.
The input control ~i n, l~ from which the attenuator control aignal (112) is derived are RSSI (212), RSSI Reference (207), and Tx Gain (208). RSSI (212), an -nAlog signAl~ is the re-S ceived signal st~ ;lh in~lic~tQr that is generated by the wide-band IF of the DS-CDMA lec~ve~. RSSI Reference (207) is used to co~np~re with the RSSI (212) to generate a Rx AGC
aignal as the o~ .ut of u~ on~l _mplifier (204). Tx Gain (208) i8 the cumulative sum of the closed loop power control 10 bits that have been ~ece;ved from the commt~nic.~tin~ baae s,ite. Both RSSI Refe~e,.ce (207) and Tx Gain (208) are digital that, in the preferred embo~li~ent~ are high frequency pulse-width-modulated PWM sign~l~. These ~ign~l~ can be generated in a D~ tor ASIC (205) as shown in FIG. 2 or 15 from a mic.o~ ese~r or DSP as multi-bit 8ign-1~ and then put through D/A cou~ e~. The PWM ~ign~ can easily be converted to _n_lo.g sign~ by low pass filtering. The low pass filter for the RSSI Reference (207) signal is coll~y,;sed of resis-tor (217) and capacitor (218). The low pass filter for the Tx 20 Gain signal is co~l..;sed of resistor (220) and capacitor (221).
In the plefelled emho~ .t the 3 dB corner of these low pass filters is 5000 Hz.
The Rs AGC (223) ~igr.~l, which is the open loop power control si~^ql, and the low pass filtered Ts Gain (208) Sign~ l, 25 which is the closed loop power control sign^-l, are comhine~ in an inverting o~e~A~;^n~l _mplifier (203) having an AC
grounded lefe~e~ce voltage on its plus lead that is half the DC
supply voltage. The relative contributions of the open and closed loop sign~ls sre controlled by resistors (216) and (219) 30 ~edpe~l;vely. These resistors are select~l relative to the feed-baclc resistor (215) and are Ir~le~l Gl*R (216) and G2~R (219).
Proper s_lec~;on of these resistors for a particular DS-CDMA
system provides the a~y.o~r;âte bAlAnce between the open loop control signal and the closed loop control signal at the output of the O~JeLAI ~m"l slmFlifier (203). The output of the opera-tional Slmrlifier (203) is fed through a resistor (214) to the in-verting input of S~not~er operS~tionSll ztmplifier (202). A resis-tor (213) provides the final gain adjllst nent of the transmitter S power control sign~ and in most cases will provide for a gain factor of one. The output of G~ l slmrlifier (202) now has the same sense as the Rs AGC (223) ~gnstlq and the low pass filtered T~ Gain (208) ~;~A18 since Amrlifiers (202) and (203) l,e-fo.. a ~o~le i~e~Dion. If the Atte~llSJtQrs (107), 10 (108), and (109) of the power control a~ tus req~ an op-poDite sense L~lDI,~it power control s~ the i~l-,er~i~g op-erSlt;~n~l Slmplifier (202) and Asso~iSlte~ resistors (213 and 214) can be removed.
In the l .efe--¢d emho~lim~nt~ the olilp~lt of op lS amplifier (202) is p~sse-l through a sample and holt circuit (201) that also co t~in~ power Amplifier control circuitry. In the plefelled embo~iimpnt~ there are three digital control sig-nal inputs to the s~mple and hold circuit (201) that are pro-~nded by the Ts Mo~lnlslt~r ASIC 206. W_Symbol_Clock (209) is 20 a pulsed signal at a 4800 Hz rate that çnS~le the trS nsfer of the o~ ,L of operS ~onSll Stmplifier (202) to the output of the sample and hold circuit (201). PA_On (210) is the overall power ~mplifier on/off control SiEnS~l If PA_On (210) is in its offstate, the Sltt~n~tQr control signal (112) is held to the level 25 that produoes a m~ v~ attenuation that is normally about 20 dB more than the low end of the normal dynamic power control range. T~c_Punct (211) is a signal that can be used to gate the transmitter output when the DS-CDMA system is op-erating at les~ than its normal filll data rate. The gating 30 pulse can be as short as 1 m~ ec~ in duration and may have fapeli~:Q- rates of several hundred Hz. An alternate way to a~omrli~h a variable data rate power control in a DS-CDMA ~ is to just drop the T~c power level l,~o~ ion-ately to the re~ ct~ in data rate. This reduction in power, howe~er, adds to the dynamic power control range of the sys-tem. Use of the Ts_Punct (211) signal to gate the trans_itter at the normal fi~ll data rate power level ~cQmpli~hss the saIne end result without increasing the dynamic range of the 5 power control d,~
A circuit that can be used for the level shift fi~nctiQ~
(110) is illu~l,Lated in FIG. 3. This circuit i8 co~l.~ised of an oper~t;on~l ~mplifier and ~rcomp~r~ying resistors. In the l,.efe..c~ emho~liment~ the resistors ha~re the saIne resis-10 tance. FIG. 4 illustrates the transfer filn^t;o~ of the level shiflc circuit. It can be seen that the output signal (113) is the input signal (112) re~ by Voff..t. Thi~ shift c~ e~ the local o~ll~t~r 8ignal ~ttenll~t~Qr (107) to delay ~ttenll~tion with respect to the ~ttenV^tion by the IF signal ~tt~n~l~tors (108 and 15 109).
lmmsry, a power cont,rol alJ~dlus for a DS-CDMA ~ otelephone has been shown. Thi~ a~ stus con-trols the tr~n~...;~ler power over a wide dynamic range while avoiding the pro~ct;on of spurious and l~nco-~t~olled trans-20 mit power.
RADIO
Field of the Invention The present invention relates generally to the field of co~ --iç~*on~ and particularly to code-division multiple acces~ (CDMA) transmitter power control.
RnrL~ .oulld of the Invention Direct-sequence CDMA (DS-CDMA) type r~Aiotele-pbon~8 .c~ e some form of power m~n~gement 8~ h~me to control the output power level of the end user's radiotele-phone'~ tra~ ,er to control ~ale,n intelferc~,ce at the input of the base site l~ece;ver. DS-CDMA is e~l~ine~ in detail in John G. Proakis, Digital Communications, 2nd Edition, pages 800-845. Ihis power m~nagement~ performed by the comhin~
tion of the base station aceiver, base st~tion transmitter, and user radiotele~one (mobile)~ ~L~e~lts a transmitting ra-~iotelep~ne from using more of the system capacity than i~
n-~e-le l for adequate communication from the mobile to t_e base St~tiQ~
This power control is l,er~med by two power control loops, an open loop for the initial es~im~ts and a closed power control loop to correct this initial estim~te. The radiotele-phone, in pe.ror lling the open loop control, uses the ~eceived signal strength in~iic~tor (RSSI) to cstim~te the signal path power 1088 from the base to the radiotelephone. The radiotele-phone can then compens~te the amount of power loss when transmitting back to the basé station. Since the loss from the base station to the radiotelephone is not the same as the ra-diotele}!hone to the base station due to generally different and ~_ - 2 -witely separated transmit and receive frequencies, this is just an initial estim~te that must be co"e~led.
The co".:~:tion, which n~oAifies the original estim~te, is ~cco~npli~h~ by the base st~t;on transmitting power control S bits to the mobile radiot~lephone at typical rates of 800 to 1000 times per second A power bit of 1 instructs the radiotele-phone to increase power by one power step and a O instructs the radiotelephone to decrease power by one power step or vice versa depen~ling on an agreed upon 8,~leul protocol. One 10 power step is a set value typically in the range of 0.5 to 1.5 dB.
The closed loop control has a typical control range of ~24 dB.
The total power control range is typically 80 dB for a 1 watt m~iml1m power mobile.
A DS-CDMA ~-~iotelephone's power ~mplifier must be 15 at least class AB linear since the m~ A~ ti~- for the system may be par~y ~mplit~lAe m~lll~te~ for all mo~ ti~n types and also to control transmitter splatter after the ml~Alll~tiol~
ba"dwidth has been set by filters before the power ~mplifier.
As is already known by one ~ le~l in the art, the ouL~.lt of lin-20 ear power amplifiers have to be controlled by some form of in-line ~ttenlliqtion and not by controlling the power supply volt-age. This c~tlse~ a problem in systems, such as the D~
CDMA radiotelephone system, where the power control re-quired has a large range. This wide power control range can 25 result in spurious radiation out of the circuits at a higher level than the desired conducted r~Ai~tjr~n~ thus interfering vwith the desired level of the tr~n~mitted ~iEn~l~. This type of radiation is also ~liffic~lt to shield adequately to keep it from interfe~ing with other circuit~ in the radiotelephone.
30 Additionally, there i9 a problem with conducted le~lra~e around variable ~tPnll~tor circuit~ that control the RF output level. There is a resulting need for a circuit that ~cco.~ ishes the vanable attenuator filnctiQn without c~ ne the spurious r~Aistior~ or le~ ge problem~.
~_ - 3 -Sllmm~ry of the Invention The power control apparatus of the present invention is S c~ ..yl;sed of a local oscillS~tQr signal path coupled to a mixer through a variaUe S~ttenllSttQr and an Il? signal path coupled to the iser through two variable S~ttem~Sttors coupled in series. The Sltten~Sttors are controllet by digital control ~c~ . The miser generates a transmit frequency signal 10 from the mi~ing of the ~tt~nl~ste l IF signal and the ~ttenttS~tE 1 local oscillator ~ign~l.
Bnef Description of the Drawings FIG. 1 shows the power control apparatus of the present .~e.... .......................... ....lion with the rec~;~,e~ front end ant l~tter back end.
FIG. 2 shows a typical transmit power control circuit in accordance with the IJresc~lt invention.
FIG. 3 shows a srhem~tic diagram of the level shift block.
FIG. 4 shows the transfer ft~nctiQn of the level shift block.
Det~ileA Description of the I~efe~ed ~JmhoAimçnt The i- liot^lephone power control apparatus of the pre-sent invention ~e.~its attenuation of DS-CDMA ~iEn~l~ before tr~nsmi~siQn without spurious or conducted ,~ t;Qn prob 30 lems. This i8 r~c~npli~heA by distributing the attenuation to both inputs of the mLlcer that generates the transmit frequency signal and keeping the power level of this signal below the level of the transmitted ~ign~l, The power control apparatus of the present invention is 35 illustrated in FIG. 1. The power control portion of FIG. 1 in-cludes elçments (106) through (113). The ~ntenn~ (101) is used to ,ec¢;ve and transmit DS-CDMA ~ign~l~ with the range of +36 to -51 dBm being a typid t~.s it power control range.
The b~n~3r~s filters (102 and 103) are cQnnected in duplex f~hion to the transmitter output and the leCeiv~r input re-S s~e~l ively. The power ~mplifier (104) i~ at least a class AB lin-ear power ~mrlifier ~p~hle of providing the nscess~ y max-imum power and gain of the ~ign~l~ from the power conk aplJ~at~s which are filtered to the final transmitter fre-quency range by the b~n~s filter (105).
The power control a~,t)a-~tus is ~,;sed of dual paths to the miser (106); one path for the local oSç~ tQr signal and the other for the IF signal from the mod~ tQr section of the typical D~CDMA tran~lter. Both paths of the power con-trol ~atus have variable ~ttenl~tnrs that are controlled by 15 a tra~s~t.ter power control circuit (111) having a digital-t~
~n910~ (D/A) co~ e~ le~ and low pass filtering. Variable atten-uators (108) and (109) are cQnnected in senes bel~.~e.. the IF
signal and the miser (106). They are controlled by the ~tteml~-tor control signal (112) from the transmitter power control cir-20 cuit (111). A variable ~tt~nll~t~r (107) is in serie~ with the lo-cal os~ll~tor signal and the 3eCo-~l input to the miser. This ~tte~n~tor, in the p~efer~¢d emho~3im~nt is controlled by a signal derived from the ~ttsnl~tQr control signal (112) that is level ~hifte~l and delayed by a level shift circuit (110). The pre-25 ferred embo~limPnt of the power control ap~a.atus is imple-mented as an integrated circuit of the rliPlectrically isolated monolithic microwave integrated circuit (DIMMIC) or another high speed bipolar or bipolar-complementary metal o~ide se_iconductor (BICMOS) process. All of these types of 30 integrated circuits, be~ e they are very small, contribute lit-tle to spurious emiSsin-l~ that would int~.L~ with the desired range of power control.
It is also necessary to control signal le~k~ge from the IF
lead of the IC to the local oscillator lead of the IC. If the entire range of power control were to be ~CCG~ sh~l without the variable attenuator (107), the ;~01At;~r~ belween the two signal input leads woult have to be greater than the desired power control range. This problem is elimin~t~ l by the variable at-5 t~nl~qtQr (107) that re~lllces the dynamic range of the attenua-tion n~e~le~l in the IF branch, thus re~itt~ ing the necessAry lead i~ol~*on. At the mid or lower end of the dynamic range of the desired mi~er output there is no problem in reducing the level of the local oscillator sign~l. This has the effect of de-lO sensitizing the mixer and reducing its gain. At high desiredoutput signal levels, level shift circuit (110) is arranged so that changes in the ~Att~n-~AtQr cG,ltwl signal (112) have no effect on the vanable attenuator (107). The variable Atte~ t~r (107) i8 controlled by a signal (113) that is pro-l-~ e-l by the level shift lS circuit (110).
In the ~.efe.~e1 emho~ ent of the l"ee.,t i~lve~t ~n, the local o~llAt~r signal operates in the range of 939 - 964 MHz and the IF signal is (115) MHz. The miser (106) gener-ates a tr~ncmit frequency signal in the range of 824 - 849 MHz 20 at a power range of +11 to -75 dBm. This signal is bAn~lrA~s filtered (105) before the power Amrlifier (104). The power am-plifier (104) in.,.~--es the power level to +38 to -48 dBm. This signal i8 then bAn-lpA~s filtered (102) again before tr~n~mi~
sion from the An~n~ at a power level range of +35 to -51 25 dBm. It can be seen from these typical power levels that the tran~,l..iller frequency is first generated at a level below the tesired AntennA oul,~ut level. This is done by ~,erfoL~ng the needed vanable Attenl~*Qn by the cQ~nhinA~;Qn of variable at-tenllAtQrs in the IF and the local os~ tQr brA~n~ hes of the 30 mi~er (106). This guarantees thst spurious ~ ~;;A1;On of the transmit frequency will be below the desired and controlled con~ cte~l antenna output.
The Att~n-l~tQr control signal (112) for the power control al.l,a~ atus of the present invention can be performed by a transmit power control circuit such as is illustrated in FIG. 2.
The input control ~i n, l~ from which the attenuator control aignal (112) is derived are RSSI (212), RSSI Reference (207), and Tx Gain (208). RSSI (212), an -nAlog signAl~ is the re-S ceived signal st~ ;lh in~lic~tQr that is generated by the wide-band IF of the DS-CDMA lec~ve~. RSSI Reference (207) is used to co~np~re with the RSSI (212) to generate a Rx AGC
aignal as the o~ .ut of u~ on~l _mplifier (204). Tx Gain (208) i8 the cumulative sum of the closed loop power control 10 bits that have been ~ece;ved from the commt~nic.~tin~ baae s,ite. Both RSSI Refe~e,.ce (207) and Tx Gain (208) are digital that, in the preferred embo~li~ent~ are high frequency pulse-width-modulated PWM sign~l~. These ~ign~l~ can be generated in a D~ tor ASIC (205) as shown in FIG. 2 or 15 from a mic.o~ ese~r or DSP as multi-bit 8ign-1~ and then put through D/A cou~ e~. The PWM ~ign~ can easily be converted to _n_lo.g sign~ by low pass filtering. The low pass filter for the RSSI Reference (207) signal is coll~y,;sed of resis-tor (217) and capacitor (218). The low pass filter for the Tx 20 Gain signal is co~l..;sed of resistor (220) and capacitor (221).
In the plefelled emho~ .t the 3 dB corner of these low pass filters is 5000 Hz.
The Rs AGC (223) ~igr.~l, which is the open loop power control si~^ql, and the low pass filtered Ts Gain (208) Sign~ l, 25 which is the closed loop power control sign^-l, are comhine~ in an inverting o~e~A~;^n~l _mplifier (203) having an AC
grounded lefe~e~ce voltage on its plus lead that is half the DC
supply voltage. The relative contributions of the open and closed loop sign~ls sre controlled by resistors (216) and (219) 30 ~edpe~l;vely. These resistors are select~l relative to the feed-baclc resistor (215) and are Ir~le~l Gl*R (216) and G2~R (219).
Proper s_lec~;on of these resistors for a particular DS-CDMA
system provides the a~y.o~r;âte bAlAnce between the open loop control signal and the closed loop control signal at the output of the O~JeLAI ~m"l slmFlifier (203). The output of the opera-tional Slmrlifier (203) is fed through a resistor (214) to the in-verting input of S~not~er operS~tionSll ztmplifier (202). A resis-tor (213) provides the final gain adjllst nent of the transmitter S power control sign~ and in most cases will provide for a gain factor of one. The output of G~ l slmrlifier (202) now has the same sense as the Rs AGC (223) ~gnstlq and the low pass filtered T~ Gain (208) ~;~A18 since Amrlifiers (202) and (203) l,e-fo.. a ~o~le i~e~Dion. If the Atte~llSJtQrs (107), 10 (108), and (109) of the power control a~ tus req~ an op-poDite sense L~lDI,~it power control s~ the i~l-,er~i~g op-erSlt;~n~l Slmplifier (202) and Asso~iSlte~ resistors (213 and 214) can be removed.
In the l .efe--¢d emho~lim~nt~ the olilp~lt of op lS amplifier (202) is p~sse-l through a sample and holt circuit (201) that also co t~in~ power Amplifier control circuitry. In the plefelled embo~iimpnt~ there are three digital control sig-nal inputs to the s~mple and hold circuit (201) that are pro-~nded by the Ts Mo~lnlslt~r ASIC 206. W_Symbol_Clock (209) is 20 a pulsed signal at a 4800 Hz rate that çnS~le the trS nsfer of the o~ ,L of operS ~onSll Stmplifier (202) to the output of the sample and hold circuit (201). PA_On (210) is the overall power ~mplifier on/off control SiEnS~l If PA_On (210) is in its offstate, the Sltt~n~tQr control signal (112) is held to the level 25 that produoes a m~ v~ attenuation that is normally about 20 dB more than the low end of the normal dynamic power control range. T~c_Punct (211) is a signal that can be used to gate the transmitter output when the DS-CDMA system is op-erating at les~ than its normal filll data rate. The gating 30 pulse can be as short as 1 m~ ec~ in duration and may have fapeli~:Q- rates of several hundred Hz. An alternate way to a~omrli~h a variable data rate power control in a DS-CDMA ~ is to just drop the T~c power level l,~o~ ion-ately to the re~ ct~ in data rate. This reduction in power, howe~er, adds to the dynamic power control range of the sys-tem. Use of the Ts_Punct (211) signal to gate the trans_itter at the normal fi~ll data rate power level ~cQmpli~hss the saIne end result without increasing the dynamic range of the 5 power control d,~
A circuit that can be used for the level shift fi~nctiQ~
(110) is illu~l,Lated in FIG. 3. This circuit i8 co~l.~ised of an oper~t;on~l ~mplifier and ~rcomp~r~ying resistors. In the l,.efe..c~ emho~liment~ the resistors ha~re the saIne resis-10 tance. FIG. 4 illustrates the transfer filn^t;o~ of the level shiflc circuit. It can be seen that the output signal (113) is the input signal (112) re~ by Voff..t. Thi~ shift c~ e~ the local o~ll~t~r 8ignal ~ttenll~t~Qr (107) to delay ~ttenll~tion with respect to the ~ttenV^tion by the IF signal ~tt~n~l~tors (108 and 15 109).
lmmsry, a power cont,rol alJ~dlus for a DS-CDMA ~ otelephone has been shown. Thi~ a~ stus con-trols the tr~n~...;~ler power over a wide dynamic range while avoiding the pro~ct;on of spurious and l~nco-~t~olled trans-20 mit power.
Claims (10)
1. An apparatus for controlling transmitted power of a code-division multiple access communication device, the commu-nication device having a local oscillating signal, an interme-diate frequency (IF) signal, the apparatus comprising:
means for generating an attenuation control signal;
first controllable attenuation means, coupled to the local oscillating signal, for generating an attenuated local oscillat-ing signal, the first controllable attenuation means changing attenuation in response to the attenuation control signal;
second controllable attenuation means, coupled to the IF signal, for generating an attenuation IF signal, the second attenuation means changing attenuation in response to the at-tenuation control signal; and mixing means, coupled to the first controllable attenua-tion means and the second controllable attenuation means, for generating a transmit frequency signal from the attenuated local oscillating signal and the attenuated IF signal
means for generating an attenuation control signal;
first controllable attenuation means, coupled to the local oscillating signal, for generating an attenuated local oscillat-ing signal, the first controllable attenuation means changing attenuation in response to the attenuation control signal;
second controllable attenuation means, coupled to the IF signal, for generating an attenuation IF signal, the second attenuation means changing attenuation in response to the at-tenuation control signal; and mixing means, coupled to the first controllable attenua-tion means and the second controllable attenuation means, for generating a transmit frequency signal from the attenuated local oscillating signal and the attenuated IF signal
2. The apparatus of claim 1 and further including third con-trollable attenuation means coupled in series with the second controllable attenuation means and the mixing means, the third controllable attenuation means changing attenuation in response to the attenuation control signal.
3. The apparatus of claim 1 and further including filtering means coupled to the mixing means for generating a filtered transmit frequency signal.
4. The apparatus of claim 3 and further including power am-plification means for amplifying the filtered transmit fre-quency signal.
5. The apparatus of claim 1 wherein the means for generat-ing an attenuation control signal is coupled to the first control-lable attenuation means by level shifting means.
6. An apparatus for controlling transmitted power of a code-division multiple access communication device, the commu-nication device having a local oscillating signal, an interme-diate frequency (IF) signal, the apparatus comprising:
means for generating an attenuation control signal;
first controllable attenuation means coupled to the local oscillating signal, for generating an attenuated local oscillat-ing signal, the first controllable attenuation means changing attenuation in response to the attenuation control signal;
second controllable attenuation means, coupled to the IF signal, for generating a first attenuated IF signal, the sec-ond attenuation means changing attenuation in response to the attenuation control signal;
third controllable attenuation means, coupled to the second controllable attenuation means for generating a sec-ond attenuated IF signal from the first attentuated IF signal, the third attenuation means changing attenuation in response to the attenuation control signal;
mixing means, coupled to the first controllable attenua-tion means and the third controllable attenuation means, for generating a transmit frequency signal from the attenuated local oscillating signal and the second attenuated IF signal the transmit frequency signal having a first power level;
filtering means, coupled to the mixing means, for gen-erating a filtered transmit frequency signal; and amplification means for amplifying the filtered trans-mit frequency signal, thus generating a signal for transmis-sion having a second power level larger than the first power level.
means for generating an attenuation control signal;
first controllable attenuation means coupled to the local oscillating signal, for generating an attenuated local oscillat-ing signal, the first controllable attenuation means changing attenuation in response to the attenuation control signal;
second controllable attenuation means, coupled to the IF signal, for generating a first attenuated IF signal, the sec-ond attenuation means changing attenuation in response to the attenuation control signal;
third controllable attenuation means, coupled to the second controllable attenuation means for generating a sec-ond attenuated IF signal from the first attentuated IF signal, the third attenuation means changing attenuation in response to the attenuation control signal;
mixing means, coupled to the first controllable attenua-tion means and the third controllable attenuation means, for generating a transmit frequency signal from the attenuated local oscillating signal and the second attenuated IF signal the transmit frequency signal having a first power level;
filtering means, coupled to the mixing means, for gen-erating a filtered transmit frequency signal; and amplification means for amplifying the filtered trans-mit frequency signal, thus generating a signal for transmis-sion having a second power level larger than the first power level.
7. The apparatus of claim 6 wherein the means for generat-ing an attenuation control signal is coupled to the first control-lable attenuation means by level shifting means.
8. The apparatus of claim 7 wherein the level shifting means delays the attenuation control signal from controlling the at-tenuation of the first controllable attenuation means.
9. An apparatus for controlling transmitted power of a code-division multiple access communication device, the commu-nication device having a local oscillating signal, an interme-diate frequency (IF) signal, the apparatus comprising:
means for generating an attenuation control signal;
level shifting means for generating a level shifted and delayed attenuation control signal;
first controllable attenuation means, coupled to the local oscillating signal, for generating an attenuated local oscillat-ing signal, the first controllable attenuation means changing attenuation in response to the level shifted and delayed atten-uation control signal;
second controllable attenuation means, coupled to the IF signal, for generating a first attenuated IF signal, the sec-ond attenuation means changing attenuation in response to the attenuation control signal;
third controllable attenuation means, coupled to the second controllable attenuation means, for generating a sec-ond attenuated IF signal from the first attenuated IF signal, the third attenuation means changing attenuation in response to the attenuation control signal;
mixing means, coupled to the first controllable attenua-tion means and the third controllable attenuation means, for generating a transmit frequency signal from the attenuated local oscillating signal and the second attenuated IF signal, the transmit frequency signal having a first power level;
filtering means, coupled to the mixing means, for gen-erating a filtered transmit frequency signal; and amplification means for amplifying the filtered trans-mit frequency signal, thus generating a signal for transmis-sion having a second power level larger than the first power level.
means for generating an attenuation control signal;
level shifting means for generating a level shifted and delayed attenuation control signal;
first controllable attenuation means, coupled to the local oscillating signal, for generating an attenuated local oscillat-ing signal, the first controllable attenuation means changing attenuation in response to the level shifted and delayed atten-uation control signal;
second controllable attenuation means, coupled to the IF signal, for generating a first attenuated IF signal, the sec-ond attenuation means changing attenuation in response to the attenuation control signal;
third controllable attenuation means, coupled to the second controllable attenuation means, for generating a sec-ond attenuated IF signal from the first attenuated IF signal, the third attenuation means changing attenuation in response to the attenuation control signal;
mixing means, coupled to the first controllable attenua-tion means and the third controllable attenuation means, for generating a transmit frequency signal from the attenuated local oscillating signal and the second attenuated IF signal, the transmit frequency signal having a first power level;
filtering means, coupled to the mixing means, for gen-erating a filtered transmit frequency signal; and amplification means for amplifying the filtered trans-mit frequency signal, thus generating a signal for transmis-sion having a second power level larger than the first power level.
10. A code-division multiple access communication device having the ability to transmit and receive signals, the device comprising:
oscillating means for generating a local oscillating sig-nal;
modulation means for generating an intermediate fre-quency (IF) signal; and means for controlling transmitted power comprising:
means for generating an attenuation control sig-nal;
first controllable attenuation means coupled to the local oscillating signal, for generating an attenu-ated local oscillating signal, the first controllable atten-uation means changing attenuation in response to the attenuation control signal;
second controllable attenuation means, coupled to the IF signal, for generating an attenuated IF signal, the second attenuation means changing attenuation in response to the attenuation control signal; and mixing means, coupled to the first controllable at-tenuation means and the second controllable attenua-tion means, for generating a transmit frequency signal from the attenuated local oscillating signal and the at-tenuated IF signal.
oscillating means for generating a local oscillating sig-nal;
modulation means for generating an intermediate fre-quency (IF) signal; and means for controlling transmitted power comprising:
means for generating an attenuation control sig-nal;
first controllable attenuation means coupled to the local oscillating signal, for generating an attenu-ated local oscillating signal, the first controllable atten-uation means changing attenuation in response to the attenuation control signal;
second controllable attenuation means, coupled to the IF signal, for generating an attenuated IF signal, the second attenuation means changing attenuation in response to the attenuation control signal; and mixing means, coupled to the first controllable at-tenuation means and the second controllable attenua-tion means, for generating a transmit frequency signal from the attenuated local oscillating signal and the at-tenuated IF signal.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US07/706,479 US5107487A (en) | 1991-05-28 | 1991-05-28 | Power control of a direct sequence CDMA radio |
| US706,479 | 1991-05-28 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2086009A1 CA2086009A1 (en) | 1992-11-29 |
| CA2086009C true CA2086009C (en) | 1996-05-14 |
Family
ID=24837764
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002086009A Expired - Fee Related CA2086009C (en) | 1991-05-28 | 1992-04-06 | Power control of a direct sequence cdma radio |
Country Status (8)
| Country | Link |
|---|---|
| US (1) | US5107487A (en) |
| JP (1) | JP3146491B2 (en) |
| BR (1) | BR9205268A (en) |
| CA (1) | CA2086009C (en) |
| DE (1) | DE4291712C1 (en) |
| GB (1) | GB2263026B (en) |
| HK (1) | HK32597A (en) |
| WO (1) | WO1992022157A1 (en) |
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| US3390335A (en) * | 1963-12-31 | 1968-06-25 | Nippon Electric Co | Frequency-diversity transmitter-receiver |
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| FR2595889B1 (en) * | 1986-03-14 | 1988-05-06 | Havel Christophe | TRANSMISSION POWER CONTROL DEVICE IN A RADIO COMMUNICATION TRANSCEIVER STATION |
| US5003619A (en) * | 1989-01-31 | 1991-03-26 | Motorola, Inc. | Method and apparatus for adjusting the power of a transmitter |
-
1991
- 1991-05-28 US US07/706,479 patent/US5107487A/en not_active Expired - Lifetime
-
1992
- 1992-04-06 GB GB9224418A patent/GB2263026B/en not_active Expired - Fee Related
- 1992-04-06 DE DE4291712A patent/DE4291712C1/en not_active Expired - Fee Related
- 1992-04-06 BR BR9205268A patent/BR9205268A/en not_active IP Right Cessation
- 1992-04-06 WO PCT/US1992/002914 patent/WO1992022157A1/en active Application Filing
- 1992-04-06 CA CA002086009A patent/CA2086009C/en not_active Expired - Fee Related
- 1992-04-06 JP JP50039293A patent/JP3146491B2/en not_active Expired - Fee Related
-
1997
- 1997-03-20 HK HK32597A patent/HK32597A/en not_active IP Right Cessation
Also Published As
| Publication number | Publication date |
|---|---|
| BR9205268A (en) | 1993-07-20 |
| JP3146491B2 (en) | 2001-03-19 |
| CA2086009A1 (en) | 1992-11-29 |
| WO1992022157A1 (en) | 1992-12-10 |
| GB2263026A (en) | 1993-07-07 |
| DE4291712C1 (en) | 1996-08-22 |
| HK32597A (en) | 1997-03-27 |
| GB2263026B (en) | 1994-09-28 |
| JPH05508987A (en) | 1993-12-09 |
| GB9224418D0 (en) | 1993-03-31 |
| US5107487A (en) | 1992-04-21 |
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