CA2607144C - Cellular network amplifier with automated output power control - Google Patents

Abstract

A system and method for amplifying cellular signals while maintaining the output power of the amplifier below a prescribed power limit. The network amplifier system may include a variable gain module having an input configured to receive an uplink signal from a handset and configured to apply an amplification factor to the uplink signal to generate an adjusted uplink signal. A detector is used for detecting a level of the uplink signal. A gain control module is configured to control the amplification factor in order to limit the output of the variable gain module to ensure that the level of the adjusted uplink signal does not exceed a predetermined limit. An antenna is coupled to the output of the variable gain module and is configured to transmit the adjusted uplink signal to a base station.

Description

CELLULAR NETWORK AMPLIFIER WITH
AUTOMAT'ED OUTPUT POWER CONTROL
BACKGROUND OF THE INVENTION

1. The Field of the Invention [001] The present invention irelates to cellular network amplifiers. More particularly, embodiments of the present invention relate to systems and methods for dynamically controlling a network amplifiei- to provide an optimal gain level and to minimize amplifier oscillation.

2. Thc lZclevant Teclinology 10021 In recent years, cellular ("cell" or "mobile") telephones have dramatically increased in popularity. A growing number of people are relying exclusively on cell phones, and are abandoning their traditional land Iine telephone services in favor of the convenience of the mobility of cell phones. Others are simply adding cell phones while retaining land line telephone services. In any case, this inci-ease in cell phone reliance has resulted in the need for reliable cellular signal coverage over a widct- area.

10031 Use of cell phones in areas having a weak signal often results in dropped calls which can be annoying toi- the cell phone user and expensive toi- the wireless service pi-ovider.
Di-opped calls typically 1-esult when the signal between the cell phonc and the base station is lost.
A(oss ofsignal may occui- tor a number of'rcasons, including intci-ferencc due, to buildings or mountains, or an increase in distance bct\,veen the cell phonc and the base station, or tor othcr reasons. Therefore, a particular necd exists to incrcase the re(iability of cell phones near large buildings and in vehicles dt-iving long distanccs in remote areas as well as othei- reasons.

10041 Attempts have been made to increase the reliability of cell phones through use of cell phone signal boosters, also known as cellular network amplifiers. Cellular network amplifiers receive the cellular signal sent from a base station, amplify the signal, and retransmit the signal to one or more cell phones. Similarly, the cellular network amplifier receives the signals frotn one or more cell phones, amplifies the signals, and retransmits the signals to the base station.
[0051 Cellular network amplifiers are typically placed in relatively close proximity to one or more cell phones, and serve the purpose of increasing the level of the signals being transinitted to and from the cell phones so that the cell phones can communicate with base stations that would otlierwise be out of range. Some amplifiers are configured to be integrated with the cell phone itself or with a cell phone cradle. /l.lternatively, other amplifiers are configured to be placed in a separate location from the cell phone itself. For example, a cellular network amplifier may be placed in a user's vehicle, or in or near a building that might otherwise have poor reception.

10061 Conventional cell phone signal boosters apply constant gain levels to the signal passing through the amplifier. A conventional signal booster typically increases signal power of an uplink or downlink signal using a constant gain level regardless of the level. of the received signal. However, if the signal booster receives an uplink signal having a high power level from a ceLlular telephone and amplifies th.e uplink signal using the constant gain level, the resultant signal may he amplifieci bcyond a prcfcrred level. Conseduently, the signals ti-ansmitted ti-om the signal booster may cause intcrl`1õrence to be introduced in the surrounding cellular network.
The lligh output levels may also overload the arnplitier, causing unwanted distortion.
FLn-thermore, regulatory age.ncies place upper limits on the cellular signal power levels can be transmitted from a device. By applying a constant levcl of gain to all signals, a cellular signal atnplifier may inadvertently violate these regulations.

- Page ? -[007] The tendency for many cell phone signal boosters to produce unwanted high power levels can create significant problems for wireless service providers by overloading and thereby disrupting cellular systems. Since wireless service providers often evaluate and approve cellular network amplifiers before they are used in the providers' systems, the providers are unlikely to approve signal boosters that produce overamplified signals.

[008] The subject matter clai.med herein is not limited to embodiments that solve any disadvantages or that operate only in environments sucll as those described above. Rather, this background is only provide.d to illusti-ate one exemplary technology area where somc embodiments described hei-ein may be practiced.

- Page; -10091 The present invention relates to methods and amplifier systems for amplifying cellular signals wllile maintaining the output power levels of the amplifier below a prescribed limit. In one embodiment, a network amplifier system includes a variable gain module having an input configured to receive an uplink signal from a handset and configured to apply an amplification factor to the uplink signal to generate an adjusted uplink signal to be transmitted to a base station. A detector is used for detecting a level of the uplink signal.
A gain control module is configured to control the ampliflcation factor in order to limit tl-ie output of the variablc gain module to ensure that the lcvel of the adjusted uplink signal does not exceed a predetermined limit. An antenna is coupled to an output of the variable gain rnodule and is configured to transmit the adjusted uplink signal to a base station.

l010] A further embodinlent is directed to a method of variably amplifying a cellular signal.
The method may be practiced, for example, in a network amplifier having one or more computer readable media having stored tliereon computer executable instructions that, when executed by a processor, can cause the network amplifie-- to perform the method. The rnethod includes receiving an uplink signal from a handset via a first antenna and ineasuring a level of the uplink signal. A detei-mination is inade as to whether amplifying thc uplink signal using an amplitication factor will generate an adjusteci uplink signal havinl; a level that exceeds a pi-ecletermined liinit. ICthe adjustccll uplink sH~nal level exeeecis the fit-st predetermined limit, the tirst amplitication factor is adjusted such that the adjusted uplink signal level i-emains below the tii-st predetcrminecl limit. The uplink signal is aniplifieci using the resultant ainplification factor, and the adjusted uplink signal is trans-nitted to a base station via a second antenna.

- 1'agc 4 -[011] In another embodiment of the itlvention, a network amplifier includes a first antenna configured to receive an uplink signal from a handset and a first detector for detecting a level of the uplink signal. A gain module is configured to apply a first amplification factor to the uplink signal to genei-ate an adjusted uplink signal. The gain module may include a first amplifier configured to amplify the uplink siignal and a multistage attenuator configured to attenuate the uplink signal. The multistage atten[uator may progressively activate stages of attenuation as the level of the uplitlk signal increase,s in order to maintain the adjusted uplink signal level below a predetermined level. The amplification factor includes a combined effect of the first amplitier and the first multistage attenuator. Finally, a second antenna is coupled to an output of the gain module and is configured to transmiit the adjusted uplink signal to a base station.

10121 This Summaty is provi(led to introduce a selection of concepts in a simplilied form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential cl-taracteristics of the claimed subject matter, rtor is it intended to be used as an aid in determining the scope of the claimed subject matter.

10131 Additional features will be set forth in the description which follows., and in pat-t will be obvious from the desct-iption, or may be learned by the practice of the teachings herein.
Features of the invention may be realized and obtained by mcaus of the ins,tnnnents and combinations particularly pointed out in the appended c[aims. Features of the I)t-esent invention will become more fully apparent lrom the tollowing description and appended claims, or may be leat-ned by the practice of the invention as set fot-th hercitiafter.

BRIEF DESCRIPTION OF THE DRAWINGS

10141 To further clarify the above and other advantages and features of the present invention, a more particular description of the invention will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings. It is appreciated that these drawings depict only typical embodiments of the invention and are therefore not to be considered limiting of its scope. The invention will be described and explained with additioinal specificity and detail through the use of the accompanying drawings in which:

10151 Figui-e 1 illustrates a block diagi-am of a cellular cominunications system;
10161 FigLn-e 2 illustrates one embodiment of a unidirectional amplifier;

10171 Figures 3A, 3B, 4A, and 4B are exemplat-y schematics of bidirectional cellular network amplitiers;

[018] Figure 5A is a flow diagram of an exemplary method for amplifying cellular signals using a network amplitiei;

[019] Figure 6 illustrates a schematic diagram of a cellular network ainplifier using a variable gain module to liinit the power output of the amplifier;

[020] Figure 7 illustl-ates a scllematic diagram of a cellular network amplifier using a multistage attenuator to limit the power output of the ampliflei;

10211 Figui-es 8A and SB illustrate plots of the power output of example amplitier-s that may be uscd in the present invcntion: and 10221 Figure 9 is a flow diagraml of an cxemplary metliod foi- variably amp(ifving a cellular signal.

Pagc6-DETAILED DESCRIPTION

[0231 In the following detailed description of the preferred embodiments, reference is made to the accompanying drawings which form a part hereof, and in which are shown by way of illustration specific embodiments iri which the invention may be practiced. It is to be understood that other embodiments may be utilized and structural changes may be made vvithout departing from the scope of the present invention.

10241 Embodiments of the invention rclate to amplifiers that enliance the ability of a device such as a cellular telephone to communicate in a wireless network. The present invention extends to a cellular network amplifier that dynamically adjusts the gain applied to a cellular signal. One elnbodiment of the network amplifier variably adjusts its gain as needed. The ability to automatically adjust the gain applied to a cellular signal can prevent the alnplifier from generating signals that may interfcre with the operation of a cellular network or with the operation of the network amplifier itself. Too much gain, for example, can cause the network amplifier to oscillate, which results in interferetlce to the cellular network and adversely iinpacts users of the cellular network. Also, too much gain increases the amount of residual noise at the base station.

10251 Embodiinents of the network amplitier can be integrated with cellular telephones (or othet- dcvices) or connect with a cellular tclephonc. The ampliticr acts as an interme.diary between a base station (oi- other cell site) anci a hanclsct (a cellular telephone or otller device).
Signals generated by the cellular telephone are amplitied and i-eti-ansmitted by the network amplifier. The network ampli tici- also receives signals from the base station and transmits them to the cellular telephone. In some embodiments, a network amplifier can act as an intermediary between a base station and multiple handsets.

10261 The cellular netwoi-k ainplifier receives a first cellular signal from a base station via a first antenna and a second cellular signal from a handset: via a second antenna. A control circuit analyzes the cellular signals to determine the presence of oscillation, and adjusts ani amplification factor in a manner that eliminates the oscillating condition. The adjusted amplification factor is applied to the first and/or second cellular signals, and the resulting cellulair signals are retransmitted via the first and second antennas to the base station and the handset, respectively.
10271 For purposes of the present invention, the following definitiotls are provided. The terms '`cellular'" and "cellular network" refer to a wireless teleplione network that connects radio transmissions between a mobile phone and a system of multiple cell sites, each including an antenna and a base station, to a mobile telephone switching otfice, and ultimately to the public wireline telephone system. Cellular calls are transferred from base station to base station as a user travels from cell to cell. One of skill in the art can appreciate that embodiments of the invention can be applied to other wireless networks including those operating on various frequencies throughout the electromagnetic spectruin.

10281 By way of example, the phrasc "'cell phone" refers to a wireless device that sends and receives messages using radiofrequency signals in the 800-900 megahertz (MHz) portion of the radiofrequency (RF) spectrum, and the phi-ase "PCS phone"" (personal communication system phone) refers to a wireless device that uses radiofrequency signals in the 1850-1990 Mtlz portion of the RF spectrum. Foi- purposcs of simplicity, as usecl herein, the terms "ccll phone"' and "handset" ai-e intended to covci- both "ccll phone" and "P('S phone"", as defined above, as well as other handheld devi.ces. Likewise, as used hei-ein, the phrase "cellular signal" refers to signals being transmitted both in the cell phone spectrum (i.e., 800-900 MHz) and in tl-ie PCS spectrum (i.e., 1850-1990 MHz). One of skill in the art can appreciate that embodiments of the invention are not limited to operation in these frequency spectrums, but can be applied in other portions of the frequency spectrum as well. In addition, other wireless devices such as personal digital assistants, laptop computers, and the like can benefit from embodiments of the invention.

10291 "Cell site" and "base station" are used herein interchangeably. Cell site and base station are defined as the locationi where the wireless nctwork antenna and cotnmunications equipment are placed. A cell site or base station typically includes a transmitter/receiver, antenna tower, transmission raclios and radio controllers for nlaintaining communications with mobile handsets within a given range.

10301 The word "uplink- refers to the transmission path of a signal being transmitted from a handset to a base station. The worci `'downlink- t-efers to the transmission path of a signal being transmitted fi-om the base station to the handset. The plu-ases "uplink signal" and "downlink signal" are not limited to any particular type of data that may be transmitted between a handset and a base station, but instead are siinply used to specify the direction in which a signal is being transmitted.

10311 Figure I shows an exemplary communications system 100. The communications system 100 may be a cellular- telephone wireless network or other wireless iietwork. In this exainple, a network amplitiei- 102 amplifies the signals ti-ansmitted between a base station 106 and a llandset 104. In a tvpical system, the network ampliticr 102 is located in close proximity to the handsct 104 in comparison to the distance to the base station 106. The base station 106 transmits a signal 108 which is attenuated tor various rcasons known to one of skill in the art as it travels outwar-d ti=om the base station 106. An anteiula 110 i-eccives the signal 108 and converts the radiateci signal into a conducted electrical equivalent.

-i'agc9-10321 The network amplificr 102 amplifies the electrical signal and cominunicates the amplified signal to the handset 104. In one example, the network amplifier 102 may retransmit the electrical signal from a second antenna 112 as an amplified RF signal 114.
The amplified signal 114 is received by an antenna 116 of handset 104, which processes the signal and ultimately communicates the appropriate content to a user of handset 104. As previously indicated, the network amplifier 102 may be an integral part of the handset 104.

10331 Similarly, the handset 104 may communicate content to the network amplifier 102 by transmitting an RF signal ti-om the antenna 116, whicll is ultimately received by the antenna 112.
The network amplitier 102 amplifies thc received sigixal and retransmits the signal using the antcnna 110. The transmitted signal is received by the base station 106, which may perfonn a number of operations on the signal, as determined by the wireless service provider.

10341 Figure 2 illustrates a generalized unidirectional amplifier 202 configured for producing an optimal gain level, in accordance with the present invention. The ainplifler 202 is connected to an antenna 210 which is contigured to receive a signal. The antenna 210 converts the received signal into an electrical signal. The clectrical signal is received by a variable gain module (VGM) 216, whicll applies an amplification factor to the electrical signal. In one embodiinent, the electi-onic signal is eommLulicated via a second antenna 212, which transmits the adjusted clccti-ical signal as an RF signal, to be received by one or moi-e liandsets or otlicr devices.

10351 Thc vai-iable gain modulc 216 is conti-olled by a control circuit 214.
The control cit-cuit 214 i-eceives the electrical signal fi-om the antenna 210, and based on the pi-operties of the electrical signal, determines an optimal amplification factor that should be applied to the electrical signal. The control circuit 214 provides a control signal to the variable gain module 216. The control signal instructs tl-ie gain module 2 16 at least as to the amplification factor that should be applied to the electrical signal. Many factors may be accounted for when calculating the required amplification factor. Factors include, by way of example and not limitation, the level or strength of the electrical signal and whether there is any indication that the network amplifier 202 is oscillating or overloading the cellular network in any way.

[0361 The amplification factor, in one embodiment, is a multiplier that is applied to the electrical signal. The amplification factor cati result in either an amplified or attenuated output signal. In other words, where the absolute value of the amplilication factor is less than one, the amplified adjustecl signal will have a lowei- amplitude than the original electrical signal.
Conversely, when the absolute value of the amplification factor is greater than one, the amplified adjusted signal will have a greater amplitude than the original electrical signal.

10371 Figure 3A illustrates one embodiment of a bidirectional network amplifier 302 configured to control the amplification of cellular signals being transmitted between a base station and a handset. Similar to network amplifier 202 illustrated in Figure 2, a cellular signal is received fi-om a base station at the antenna 310 and is passed to both a control eircuit 314 and a variable gain tnodule 316. Control circuit 3 14 controls the amplification factor of variable gain module 316. The amplified signal may he connected to a second antenna 312, vvhich ti-ansrnits a cellular signal to at least one handset.

10381 Bidirectional cellular amplitier 302 is also configurcd to receive sigiiials from one or mot-e handsets, amplify those signals, and reti-ansmit the signals to a base station. A signal from a handset may be received by antenna 3I2. The signal is routed to a secortd variable gain module 304, which applies an amplification tactor to the signal. The amplilication factor is determined and contt-olled by conti-ol cii-cuitry 314.

- Page I I -(039] In order to allow antennas 310 and 312 to simultaneously transmit and receive signals, duplexers (DUP) 306 and 308 are provided by way of example. A
duplexer is defined, by way of example, as an automatic electrical routing device that permi:ts simultaneous transmitting and receiving through a common point. More generally, a duplexer is a three port device with one common port "A" and two independent ports "B" and "C".
Ideally, signals are passed from A to B and from C to A, but not between B and C. For example, the duplexer 306 receives an RF signal from a base station and converts the signal into a first electrical signal, which is routed to the inputs of thc variable gain devicc 316 and the control cii-cuitty 3 14. The duplexer 306 simultaneously receives a second electrical signal fcoin the output of the variable gain module 304, and causes this signal to be transtnitted as an RF signal via the antenna 310.
10401 The control circuitry 314 may be configured to accomplish various objectives when determining the amplification factors to be applied to the variable gain modules 304 and 316.
Exemplary objectives include, but are not limited to, i) setting the power level at which the signals are transmitted at a sufticient level to ensure that the signals reach a target destination;
and ii) ensuring that the signals transmitted from the network amplifier are transmitted at a power level that substantially elimiii7ates the interference that would otherwise be introduced into the surrounding cellular network.

10411 First, the control c.ircuitry 314 establishes the amplification tactors of the variable :.,rain modules 304 and 316 so that the resultant signals are transmitted with suHicient power to adequately reach a target destinatir.)n, such as a handsc:t or a base station.
Whe;t-e the cellular signal received at the antenna 310 has undergone significant attenuation, e.g., when the target destination is located a long distance away ti-om the network amplifier 302, the amplification factor is incrcased. Conversely, where the ccllular signal reccived at the antenna 310 is at a sufficiently high level, a lower aniplification may be established for variable gain modules 316 and 304.

10421 Second, the control circuitry 314 ensures that the signals transmitted from the network aanplifier are transmitted at a power level that substantially eliminates the interference that would otherwise be introduced into the surrounding cellular network. Many cellular networks, such as CDMA systems, are configured such that the power level transmitted by each handset in the netwot-k is deterrr-ined by the base station. When communication between a handset and a base station is initiated, a"handshake"' occurs between the handset and base station, and the base station instructs the handset as to the powet- at which the handset sltould transmit. If the base station detcrniines that the signal f--om the handset is too strong, it will instruct the handset to t-educe the power level of the transtnitted signal.
The CDMA system is designed so that all of the signals coming into the base station are of approximately the same power. If one signal arrives at the base station at a power level that is significantly higher than the others, it can potentially overpower the base station and cause interference 'with the other handsets in communication with the base station. If the signal arriving at the base station does not 11ave enough power, it will not be intelligible due to the sirnultaneous presence of stronger signals.

10431 Therefore, the control circuitt-y 314 may determine the maxinlum anlplitude or power level that can be transmitted by antenna 3) 10 to substantially eliniinate interference. Interference is considered to be substantially eliminated when signals at=e transmitted ti-orn the network amplifier 302 without causing hartnful effects to the surrounding cellular network. For example, interference is substantially eliminateci where the sibnals are transmitted without overpowering the base station, or otherwise interfering witll otller hanclsets within the cellular network in a way that degrades their performance. Tlic control circuitry 314 may establish the amplification factors applied to variable gain modules to either attenuate or amplify the electrical signals in order to achieve this objective.

10441 The determination of the amplification factor values may be dependent on whether the signals received from the base station via antenna 310 exceed a threshold value. The threshold value may be a predetermined set value, or may be a variable that is not established until the control circuitry 314 rnakes a detet-inination. For example, if after analyzing the strength of the signals received via antenna 310, the control circuitry 314 (leterrnines that the signal attenuation between cellular network amplifler 302 and the target base station or liandset is substantial, the control circuitty 314 may establish higller tlu-eshold values than if the base station signal was less attenuatecl. The higher threshold values would all,;)w a greater amplification factor to be applied to the signals so that the transmitted signals will reach their target destination. Because of thc substantial distance over which the signals must traverse, the signals will arrive at the target destination (e.g., a base station) without exceeding an appropriate power level, and will therefore not overpower the base station or cause substantial interference with signals transmitted froin other handsets.

10451 In the embodiment of Figure 3A, the amplific.ation factors applied to the variable gain modules 316 and 304 arc both cletcrmined based on the attributes of the signal received fi-om a base station via the antenna 310. The input signal Irom the base station is received by the control cii-cuitry 3 14 fi-om the antcnna. 31O at the co>uiection 31 8. The control circuitry 3 14 can make a number of determinations based on the attributes of the base station signal.
First, the control circuitry 314 can detennine the amplitude level of ttic signal from the base station. Bascd on the amplitude, the control circuitry can detci-mine an adcquate amplitication factor for the variable gain module 316 to enable comnlunication of the received signal to a handset.
Second, the amplitude of the signal received from the base station is also an indicator of ithe amplitude required to successfully transmit a signal back to the base station via the antenna 310. For example, if the control circuitry 314 measures a low amplitude of the first electrical signal, it is likely that the signal transmitted by the base station has been substantially attenuated between the base station and the network amplifier 302. Therefore, it can determine the amplification factor required by the variable gain module 304 so that the second electrical signal originating from the handset is retransmitted with sufficient power to reach the base station.

10461 Figure 3B illustratcs another enibodiment of a network amplitier.
Siniilar to the network amplificr illustrated in Figure 3A, the nctwork anlplifier 352 iiicludes an antenna 360, a first and second duplexer (DUP 1) 356 anci (D[JP 2) 358, respectively, a first ancl second variable gain module 354 and 366, (included within the dashed boxes), control circuitry 364 (indicated by the dashed box), and an antenna 362. More particularly, the variable gain module 366 includes a low noise amplifier (LNA) 368 and a gain controlled amplifier (GCA) 370. The gain module 354 contains an intennediate amplitier (IA) 374 and a gain controlled amplifier (GCA) 372. The gain controlled amplifiiers 370 and 372 may be voltage controlled amplifiers, digitally controlled prograrnmable gain amplitiers, and the like. 'The input of the control circuitry 364 is received from the output of the low noise amplifier 368 for providing an adequate signal to be used 1-or dctcrmining the amplification factors.

10471 The conti-ol circuitry 364 includes, in this cxample, a detector amplitici- (DA) 376, an RF detector 378, and a gain cont--oller 380. Detector ampliher 376 amplifies the input signal to a level sufficient for di-iving RF' detcctor 378. 'I'he RF detector 378 produces an output which is indicative of the signal level procluced by the output of the low noise ainplifier 368. As described above, the control circuitry 364 may be configured to accomplisll various objectives when determining the amplificatiort factors to be applied to the variable gain modules 366 and 354.

[048] For example, based on the output of the RF detector 378, the gain controller 380 may increase the amplification factors applied to gain controlled amplifier 370 or 372 to ensure that the resultant signals have sufficient power and amplitude to provide satisfactory results. Where the input signal received by the network amplifier 352 by mcans of antenna 360 is sufficiently weak, the gain controller 380 typically sets the amplification factors to a maximum available value.

10491 Furthennore, the gain controller 380 may decrease the amplification factors wllere it is determinecl that the signal levels would otherwise overload the base station, or otherwise cause harniful interference to the cellular network. In one embodiment, wllen the output of the RF
detector 378 exceeds a predetermined threshold, the gain controller 380 tut-ns off the gain controlled amplifiers 372 and 370. In other words. the control circuit 364 switches the amplification factor to a zero value when the level of the cellular signal received from the base station exceeds a predeternnincd value, and switclles the amplitication factor to a non-zero value when the signal level falls bclow the predetermined value.

111501 In another embodiment, the gain controller 380 does not simply switcli the gain contt-olled amplifiet=s on oi- off; but iustead adjusts the amplilication relativc to tl-te level of the signal receiveci from the base station. In othcr words, the control circuit 364 sets tl-ie value of the amplification factors as a function of the level of the cellular signal received from the base station.

- I'age 16 -10511 In one embodiment, the amplification factors applied to the gain controlled amplifiers 370 and 372 are equivalent. However, in another embodiment, the amplification factors applied to the gain controlled amplifiers 370 and 372 need not be the same. Although the gain controller 380 may only receive a single input signal, the gain controller may be configured to have two independent output signals to account for the unique requirements of the gain controlled amplifiers 370 and 372. In another embodiment, the changes made to the first and second amplification factors occur in identical incremental amounts. Therefore, even where the values of the amplification factors may not be identical, the changes made to the first amplitication factor may match the changes made to the seconci amplitication factor.

10521 Figure 4A illustrates another embodimcnt of a network amplitier 402 configured to generate optimum gain levcls for the transmission of signals including radio or cellular type signals. The embodiment illustrated in Figure 4A includes first and second antennas 410 and 412, respectively, first and second duplexers (DUP 1) 406 and (DUP 2) 408, respectively, first and second variable gain modules (VGM) 404 and 416, respectively, and processor 414. The anteiula 412 is configured for transmitting cellular signals to at least one hiandset, and for receiving cellular signals tcom the saine. The processor 414 may include analog circuits, digital circuits, a microprocessor, a prograrnmable logic unit, an ASIC, an FI'GA, and the like.

10531 The processor 414 controls thc amplitication tactors applied to the variable gain modules 404 and 416. Similar to the conti-ol cii-cuitrv 314 of the embodime,nt illustrated in Figure 3A, the pi-ocessor 414 may be con[igurcd to ensure that sufficient gain is applicd to thc cellular signals to ensure that the signals reach tlicir target destination, and further cnsure that the power level at which the signals are sent does not overload the base station.

[0541 Therefore, similar to the embodiment of Figure 3B, the processor 414 niay determine the maximum amplitude or powcr level that can be transmitted by antennas 410 and 412 to substantially eliminate interference. As described above, interference is considered to be substantially eliminated when signals are transmitted from the network amplifie;r 402 without causing harmful effects to the surrounding cellular network. For example., intcrference is substantially eliminated where the signals are transmitted without overpowering the base station, or otherwise interfering with the base station or with other handsets within the cellular network in a way that degrades theii- pertorinance.

10551 The processor 414 inay furtller be configui-ed to minimize the amplitication of noise that may accompany a cellular signal. Unwanted noise may include noise introduced from the surrounding environment, thermal noise, and the like. Noise can be problematic, for example, if a network amplifier is located in close proximity to a base station but still applies a. large amount of gain to the cellular signal. In some cases, if noise is significantly amplified, the noise level often exceeds the level of the celhzlar signal. The processor 414 may establish the amplification factors applied to variable gain modules 404 and 416 to either attenuate or amplify the electrical signals in order to reduce the level of amplified noise in the cellular signal and preclude overloading the base station.

10561 "l'hc determination of the amplitication factor values may be depende:nt on whether the signals i-eccived liom the base station via antennas 410 oi- 412 exceed a threshold valuc. The tlu-eshold value may be a predeterrnined set value, or may be a variable that is not established until the processor 414 makes a determination based on the propertics of the reccived signals.
For example, if after analy7ing the signals i-eceived via antenna 410 and/or 412, the processor 414 determines that the signal attenuation between cellular network amplifier 402 and the target -Pagc 18-base station or handset is substantial, the processor 414 may establish higher threshold values than if the base station signal was less attenuated. The higher threshold values vrould allow a greater amplification factor to be applied to the signals so that the transmitted signals will reach their target destination. After being amplified by the amplification factors determined by the processor 414 and transmitted frorn the antennas 410 and 412, the signals have sufficient power to arrive at the target destination (e.g., a base station or a handset), but are not amplified to such an extent that the base station will be overpowered or as to cause substantial interference with signals transmitted to or from other liandsets.

10571 The amplitication factors applied to variable gain modules 404 aiid./or 416 may be calculated using the characteristics of the signals received from the handsets, as well as from the base station. In this example, the processor 414 receives input signals from the antenna 410 and the antenna 412 (i.e., connections 418 and 420, respectively). By monitoring the characteristics of the signals received trom the handset and frotn the signals received from the base station, the processor 414 can make more accurate detertninations regarding the level at which signals should be transmitted to the base station and to the handsets.

10581 In addition to accomplishing the above objectives, the processor 414 may further be configured to substantially eliminate oscillation that may be generated by the network amplifier 402. When multiple antennas (c.t,.. antennas 410 anci 412) are employed, embodiments of the invention ensure that the nct -oi-k amplificr 402 does not begin to oscillate.
If the antennas 410 anci 412 are too close to each othcr, an oscillation may result, which will likely cause harmful intei-ference to a base station and/or the handsets connected to it and preclude effective communications. Oscillation in the network amplifier 402 is typically caused by feedback that may occur between the two antetinas 410 and 412. If the gains produced by variable gain modules 404 and 416 are sufficiently low, the network amplifier 402 will remain stable.
However, when the gains are high and/or if the antennas are physically too close to each other, the system will likely become unstable, and begin to oscillate.

10591 The introduction of oscillation by an amplifier into a cellular network can be a serious problem. Network amplifiers are often installed by an end user instead of by a wireless service provider. Consequently, the wireless service provider cannot easily predict or mitigate the interference introduced by oscillation. The oscillating signals produced by the tletvvork amplifier 402 can extend beyond the intended target (i.e., the base station or handset) and intermingle with other signals. As a result, an oscillating signal fi-om one cellular network amplifier can disrupt the communication links between a base station and the handsets witlzin range of the oscillating amplifier. Since such oscillating signals are not on controlled frequencies, they niay even interfere with other users of the elec:tromagnetic spectrum.

10601 For example, a common use for the network amplifier 402 is to aniplify cellular signals being transmitted to and h-orn a building. In an in-building scenario, the network amplifier 402 may be configured sueh that the antenna 412 is located within the interior of the building, and the antenna 410 is located on the exterior of the building.
Cellular signals transmitted fi-orn a base station ai-e. received at the external antetuta 410, amplitied by variable gain module 416 in accordance with the amplificartion established by processor 414, and retransmitted by the intei-nal antenna 412. Because the signals received from the base station are on the sanle fcequency as tllc signals transinitted by the antenna 412. a potential for feedback exists, thus increasing the likelihood of an oscillating circuit. This likelihood is particularly high where the antennas 410 and 412 arc located within close proximity to one another, and where the amplification of the variable gain miociules 404 and 416 are set at a high level.

[061] Therefore, the processor 414 may be configured to prevent the occurrence of oscillation within the network amplifier 402. The processor 414 achieves this objective by analyzing the signal levels of the iniputs 418 and 420. When an oscillating condition exists, the levels of the signals received via the antennas 410 and 412 are typically significantly higher than when the network amplifier 402 is operating normally.

10621 When the processor 414 detects conditions that may indicate oscillation, the processor 414 will eliminate the oscillating condition. The processor 414 may turn off the entire network amplitier 402 so that the handsets communicate directly to the base station instead of through the amplitier 402. Alternatively, the processor 414 may first attempt to only turn off the vai-i.able gain modules 404 or 416.

10631 In an altel-native embodiment, the processor 414 may decrement the amplification of the vat-iable gain modules 404 or 416 until the oscillation ceases. By decrementing the amplification factors instead of immediately shutting off the network amplitier, the oscillation can be eliminated while still maintaining some level of gain. This process can be applied to the variable gain modules 404 and 416, simultaneously together, one at a time, or any other manner.
10641 The network amplifier 402 may include a visual display for indicating the existence of an oscillating condition. For example, the visual display may include a ligl-it emitting diode (LED), or the like. The display may indicate that an oscillation has occui-red in the past (but has since becn climinatcd by eitllci- shutting down the amplificr 402 or by reducing the gain of the variable gain modules 404 and/or 416) and may indicate the pi-csence of an exi.sting oscillation.
After a user is aware of an oscillating condition. the user may reposition the antennas 410 and/or 412 so that the amplifler 402 may produce a larger gain without the introduction of oscillation.

[065] Figure 4B illustrates another embodiment of a network amplifier. Similar to Figure 4A, the network amplifier 452 includes first and second antennas 460 and 462, respectively, first and second duplexers 456 and 458, respectively, first and second variable gain modules, indicated by dashed boxes 466 and 454, respectively, and control circuitry, indicated by dashed box 464.

10661 The first and second variable gain modules 454 and 466 may include low noise amplifiers (LNA) 468 and 482, controllable attenuators (CATT) 470 and 484, intermcdiate amplifiers (IA) 472 and 486, and gain controlled amplitiets (GCA) 474 and 488.
The electrical signals generated by antennas 460 and 462 are initially amplified by the low noise amplifiers 468 and 482. The resultant signals nlay he attenuated by controllable attenuators 470 and 484. Thc amount of attcnuation is dependant on first anci second attcnuation factors, as determined by the control circuitry 464. The resultant signal is amplified and buffered by intermediate amplifiers 472 and 486. 'The use of intermediate amplitiers 472 and 486 may vary dependirig on the gain levels required of the cellular network amplifier 452. 'The resultant signal is amplified by the gain controlled amplifiers 474 and 488 by an amount dependant on gain factors as detennined by the control circuitry 464.

10671 The control cit-euitry 464 includes, in this example, at least two detectors 478 and 490 tliat detect the signals at the output ol'the intermcdiate amplifiers 472 and 486. The i-esults arc provided to processor 480, which cletennines amplification tactors foi- the variablc gain modules 466 and 454. Each amplitication tactor includes a gain factor for the gain controlled amplificr 474 or 488, and an attenuation tactor for the controllable attenuator 470 or 484. The processor 480 may increase or deci-ease the gain applicd to the electrical signals while attempting to ensure that the transmitted signals rcacll their target destination (i.e., a handset or a base station). In the - Pagc 22 -present embodiment, gain is increased by increasing the gain factor applied to the gain controlled amplifier 474 or 488. The processor 480 thus controls the gain applied to the gain controlled amplifier 474 or 488.

10681 The processor 480 may further be configured to reduce or substantially eliminate interference that may be caused, by way of example, from overloading the base station, overamplification of thermal noise, and the like. As described above, when the amplifier 452 emits signals at excessive power levels, the base station may be overloaded, causing interfcrence with the overall cellular network. Therefore, the processor 480 monitors the signal levels as provided by detector 478 or 490 to determine whether the signal levels exceed a thresllold value.
When ttle threshold is exceeded. the processor 480 may t-educe the overall gain by either increasing the attenuation factor applied to the controllable attenuator 470 or 484, or by decreasing the gain factor applied to the gain controlled amplifier 474 or 488.

10691 The processor 480 may sitnilarly be configured to reduce or elimitlate interference that may be caused from oscillation. When the detector 478 or 490 provides readings that indicate an oscillating condition, the processor 480 may incrementally change the attenuation factors applied to the controllable attenuators 470 and 484 and/or the gain factors applied to the gain conti-olled amplitier 474 ot- 488 in order to reduce the overall gain produced by the variable gain module 466 or 454. Thc attenuation tactor may bc inct-ementally increased, and the gain factor may be incretnentally dccrcased. After each incremental change in the attenuation andior gain factors, pt-ocessot- 480 analyzes the signal levels to cletermine if the oscillatitlg condition still exists. If the amplitier 452 is stilil oscillating, the processor 480 increments the gain and/or attenuation factors again, and repeats the pt-ocess until the oscillation has been eliminated, or at least rcduced to an acceptable level.

-Page2i-10701 In one embodiment of the present invention, additional detectors 476 and 492 are provided for the purpose of quickly eliminating any oscillation that may be generated by the network amplifier 452. While detectors 478 and 490 can be used to eliminate or reduce any oscillation by incrementally changing the gain and attenuation factors, as described in the previous embodiment, this mechanism may be too slow to preclude interference.
Unfortunately, significant disruption can be caused to a cellular network within a much shorter period of time when an amplifier is oscillating. Therefore, detectors 476 and 492 are emploved to provide a safety mechanisn-- that can immediately climinate oscillation when the oscillation exceecls a predetermined level. The detectors 476 and 492 provide the pi-ocessor 480 with a reading of the signal level at the output of thc low noise amplifler 468 or 482. If this reading exceeds a predetermined level, the processor 480 immediately shuts down all elements of the network amplifier 452 that are causing the oscillation to occur. The user is notified of the oscillation condition, and the user may reposition the antennas 460 and 462 in an attempt to eliminate the condition creating the oscillation. In this manner, disruption due to high levels of oscillation is prevented.

10711 Figure 5 illustrates a tlow diagram for an exemplary embodiment of the present invention. The following descriptioin of Figure 5 may occasionally refer to Figures 1-413.
Altllough i-eterence may be made to a specilic element from these tigures, sucli elcments are used for illustrative purpose5 0nly and are not mcant to limit or otllerwise narrow the scope of the present invention unless explicitly claimecl.

10721 Figure 5 illustrates a tlow diagi-am for a method 500 of variably amplitying a cellular signal. Method 500 includes receiving 502 a downlink signal from a base sitation via a first antenna, and receiving 504 an uplink signal from a llandset via a second antenna. As shown in -Pagc24-Figures 4A and 4B, the uplink signal may be received from antenna 410 or 460, and the downlink signal may be received from antenna 412 or 462.

[0731 The properties the downlink and/or uplink signals are analyzed 506 to determine a required signal level at which a signal should be transmitted by a network amplifier in order for the signal to reach the base stationi. In the exemplary embodiments of Figures 4A and 4B, a processor 414 or 464 performs the analysis of the cellular signals and the adjustment of the amplification factor.

10741 An amplification factor is then determined 508 such that wllen the amplification factor is applied to the uplink signal, the levc] of the resultant amplitied uplinlc signal satisfies the requii-ed signal level, as detet-mined at 506. hi one embodiment, the step of determining 508 the amplification factor fur-ther eomprises selecting the amplification factor so that interference introduced into the surrounding cellular network by the transmission of the adjusted uplink signal is substantially eliminatetl. For example, the signal level of the downlink and/or uplink signals may be measured and compared to one or more predetermined values. If one or both of the signal levels exceeds the predeter-mined values, the amplification factor may be reduced in ordcr to prevent the introduction of interference into the cellular network.
Furtliermore, the amplitication factor may include a first and second amplification factor. the first amplification factor being applied to the uplink signal, and the second amplification factor bcing applied to thc downlink signal. The seconcl arnplilication factor may also be selectecl so that interference introduced into the surrounding c,cllular netwoi-k by the transmi5sion of the acljusted uplink signal is substantially eliminated.

10751 The adjusted amplification factor is then applied 510 to the uplink signal to generate the amplified uplink signal. Finally, the amplified uplink signal is transmitted 512 to the base station via the first antenna.

[0761 Figure 6 illustrates another embodiment of a network amplifier 602 that is designed to maintain the power output levels of the network amplifier below predetermined levels. In many of the above embodiments, the variable gain modules are controlled by a controller or processor in order to achieve a desired result. For example, in Figures 2 and 3, the controllers are designed to control the power output of the network amplifiers in order to reduce or eliminate network interference introduced by the signals transmitted from the network amplifiers. In Figures 4A
and 4B, the processors are desigmed to control the power output of the network amplifiers so as to reduce or eliminate oscillating conditions that may be caused by excess power levels generated by the network amplifiers. In cet-tain situations, it inay be desirable to maintain the power levels of the signals transinitted from the network amplifier below a desired level. For example, it may be the case that a power level above a predeterrnined leve] is highly likely to introduce interference into the surrounding network. Alternatively, power levels above a certain level may saturate one or more of the amplitiers being used, thereby introducing unwanted noise into the signal. Furthermore, regulatory ageneies often place upper limits on the cellular signal power levels that can he transmitted from a device. I'beretore, it may be dcsirable to limit the powcr Output levcls, cven whcrc Iligh output levels may otherwise be desired due tO the likelihood of signal attenuation.

10771 Theretore, in the cui-i-en1, embodiment, a gain control module 614 is provided in order to ensure that the signals transmitted from the network amplifier 602 are maintained below a predetermined level. The network amplitier 602 may also include an antenna 612, a first duplexer 608, a detector 620, the first variable gain modules 604, a second duplexer 606, and a second anteruia 610. The detector 620 measures the level of an uplink signal received by the antenna 612. The gain control module 614 determines whether the current amplification factor being applied to the uplink signal by the variable gain modules 604 will produce an amplified signal that exceeds a predeter-mined level. If the amplified uplink signal exceeds the predetermined level, the gain control module 614 may adjust the amplification facitor applied by the variable gain module 604 suicil that the amplified uplink signal will not exceed the predetermined level. In the present embodiment, the maximum allowable power output may not be exceeded regardless of how much attenuation the signals may undergo in route to thcir target destinations (i.e., the handset or the base station).

10781 In otie embodiment, the gain control module 614 and the detector 620 may be combined into a single device capable of perfot-ining the tasks of detecting the uplink signal level and of controlling the variable gain module 604. In another embodiment, the detector 620 may measure the output level of the variable gain modulcs 604 instead of the input level to the variable gain rnodule 616, such that the detector 620 detccts the level of the amplified uplink signal. In this embodiment, the gain control module can perfot-tn a direct comparison of the amplified uplink signal level to the predetermined level to detertnine if the amplification factor applied by the variable gain moduhc.s 604 should be reduced.

10791 In one embodiment, the network amplttler 602 lUt'tller tncludes a second detector 618 and a second variable gain moclule 616. "t'hc detector 618 measures the level of the downlink signal received li-om a base station by the antenna 610, similar to the above description of the detector 620. The gain control rnodule 614 may adjust the gain applied by the variable gain module 616 such that the amplificd downlink signal produced by the variable gain i-nodule 616 remains below a predetermined level.

[0801 In one embodiment, the limits established for the output power of the variable gain modules 604 and 616 may be the same, i.e., the gain control module 614 insures that the amplified uplink signal produced by the variable gain module 604 and the amplif ed downlink signal produced by the variable ga.in module 616 remain below the same maxilnurn power limit level. In an alternative embodiment, the maximum power limit for the amplified upl.ink signal may diffet- from the maximum power limit level for the amplitied downlink signal.

10811 In one cmbodiment, the gain control module 614 causes botli of the variable gain modules 604 and 616 to apply the same amplification factors to both the uplink signal and to the downlink signal, respectively. In another embodiment, the gain contY-ol inodule 614 may control the gain levels of the variable gain modules 604 and 616 independently from one another. By independently controllitig the gain lcvels, the gain control module 614 can account for various unique situations that may arise.

10821 For exainple, two people may be using handsets that are eac11 transmitting signals that are being amplificd by the network anlplitier 602. One of thc handsets may be in close proximity (e.g., 5tt.) to the antenna 612, while the othcr handset may be a substantial distance (e.g., 50tt.) fronl the antCnna 61 -1. WhCn the lntcnna 612 recClves CL1Ch of the slgnals, the signal transmitted ti-on1 the handset that is a far away fronl tlle antcnna is likely moi-c attenuated t11an the signal transmitted ti-om the handset that is close to the antenna.

10831 However, when the detcctor 620 nicasures the signal level of the uplink signal, a relatively strong signal level is detected due to the close proximity of one of the handsets.
Therefore, the gain control module 614 may instruct the variable gain modules 604 to apply a relatively low amplification factor to the uplink signal. If the gain control module 614 were to apply the same amplification factors to both variable gain modules 604 and 616, the variable gain module 616 amplifying the downlink signal from the base station would also apply a low amplification factor to the downlink signal. Therefore, the handset that is a substantial distance from the antenna 612 will likely receive a weak signal and have poor reception. However, by controlling the amplification factors of the variable gain modules 604 and 616 independently, in accordance with the present embodiment, the amplification factor applied by the downlink variable gain moclule 616 can be maintained at a lligher level than the amplification factor applied by the uplink variable gain module 604 so that the handset that is far away from the antenna 612 will receive a sufticiently strong signal.

10841 Therefore, in general, one embodiment of the invention allows the second amplification factor to exceed the first amplification factor, such that the downlink signal is amplified nlore than the uplink signal. In another embodiment, the second predetermitled limit is established at a higher lcvel than the first predeterinined limit, such that the amplified downlink signal is allowed to reach a greater overall power output than the amplified uplink signal.

10851 Figure 7 illustrates an alternative embodiment tor limiting the power output of the network Lin-iplifier 702. Multistage conti-ollable attenuators 722 and 724 are provided for attenuating the uplink and'or downlink signals when the signal levels detected by the detectors 718 and/or 720 exceed a predetermined level. 'I'he aniplifiers 704 and 716 may apply a fixed gain level to the uplink and downlink signals, respectively. As the signal levels increase, the attenuators 722 and 724 progressively activate stages of attenuation in order to maintain the amplified signals below predetermined limits.

10861 The gain control module 714 receives a signal level from the detectors 718 and 720.
The gain control module 714 deteirnines if the output of' the amplifiers 704 and 716 will exceed the predetermined power limits of the network amplifier 702. If the power limits will be exceeded based on the existing amplification levels, the gain control module 714 activates an appropriate attenuation necessary to maintain the amplified signals below the predetermined limits.

10871 Although the embodiments illustrated in Figures 6 and 7 provide variable gain modules to limit thc output pM~er of botli the uplink signals and the downlink signals, in one embodiment the power is only limited on eitlzer the uplink signal patli or the downlink signal path. In such a case, the uplink or the downlink signal may be limited as dcscribed above, and the other signal may be amplitied by a constant gain, or by using any of the other techniques described herein, as well as other teeliniques.

10881 Figures 8A and 8B illustrate response plots for an example amplitier that may be employed for applying an upper power limit on the amplified uplink and downlink signals, and which may be controlled by a gain control module described previously. Figure 8A illustrates the maximum output powei- (Y-axis) of the network amplifier for a given input power (X-axis) and Figure 8B illustrates the maximum gain of the amplifier (Y-axis) for a given inpLrt power (X-axis).

10891 As illustratcd in Figure A. the maximum output power of the example amplifier may increase linearly until it reaclics a maximum predetei-mined limit as establislled by a gain control nlodule. In the present example, the maximLUn predeterinined power output limits cori-espond to input power levels "Pi" and -P,.- As shown in Figure 8B, until reaching the maximum allowable output power (at input power "Pi" and "P,"), a constant level of maxii-rium gain may - I'age ')0 -be applied by the amplifiers. Referring again to Figure 8A, the maximum predeterrnined limit of the uplink signal may exceed the maximum predetermined limit of the downlink signal. As shown in Figure 8B, upon reaching the maximum allowable power (at input power "Pl" and "P-,"), the gain control module may begin to reduce the maximum gain applied to the signals, thereby maintaining the output power below the predetermined limits.

10901 As illustrated by the solid lines 802, 804, 806 and 808 in Figures 8A
and 8B, the gain control module nlay reduce the gain levels applied to the uplink and downlink signals at a gradual rate, thereby allowing the output powel- to acllieve the nlaximunl allowable limit for any given input power. Alternatively., the dashed lines 8 10, 812, 8 14 and 8 16 describe the power output and perceived gain of the amplitiers in Figure 7, whcre multistage attenuators are used for reducing the gain of the amplitier. As the input power incl-eases, the gain control module progressively activates additional stages of attenuation in order to maintain the output power below the prescribed linlits. Eacll level of attenuation relates to an immediate reduction in the gain (Figure 8B) as well as an immediate reduction in output power (Figure 8A).

10911 As described previously, the maximum allowable output power for the uplink and downlink signals nlay differ. Furth[ermorc, the gains applied to the uplink and downlink signals may differ. For example, refening again to Figui-c SB, t.ipon l-eaching the input power Pi, a gain control module may begin to reduce the maximum allowable gain tor the uplink signal, wliile allowlllg the downhnk signal to remain at the orlf~lllal lllaxiil'1L1111 galn level. Tllls causes the output power of tlle uplink signal to reacll and remain at a maximuln levcl, as illustrated in Figure 8A. (Jpon reachillg tlle inpLlt power P,, the gain control lnoclule may begin to reduce tile maximum allowable gain for the clownlink signal, as illustrated in Figure 8B.
This causes the -Page 3) 1 -output power of the downlink signal to reach and remain at its maximum level, as illustrated in Figure 8A.

[0921 In the Figure 8B example, the uplink gain exceeds the downlink gain at input powers above Pi. However, in other embodiments, the downlink gain may be allowed to exceed the uplink gain.

10931 Figure 9 illustrates one embodiment of a method 900 of variably amplifying a cellular signal. The method 900 may be practiced, for exaniple, in a network ainplifier. The network amplifier may inclucie one or rnore computer-readable media having cornputer-executable instructions, that when executed, implement the method 900. The method 900 receives 902 an uplink signal from a handset, for example, via a first anteuna. The level of the uplink signal is measured 904, for example, using a detector 620, as illustrated in Figure 6.
'The level of the uplink signal may be measured either before or after the uplink signal is amplified, for example by a variable gain inodule 604.

10941 The method 900 then determines 906 whether the level of an amplified uplink signal will exceed a predetermined lianit. If the predeterinined limit is exceeded by the amplified uplink signal, the method 900 further includes adjusting 908 the ampliftcation factor to be applied to the uplink signal such that the amplitied uplink signal level remains bclow the predetermined limit.
In one embodiment, the amplil7cation tactor is adjusted by progressively activating stages of attenuation as the levcl of the uplink signal incrcases in order to maintain the level of the amplified uplink signal below the predeterminccl limit.

10951 The resultant amplification factor is then used to amplify 910 the uplink signal, and the ampii fied signal is ti-ansmittcd 912 to a base station N-ia a second antenna.

, [0961 A similar method nlay also be performed on the downlink signal in order to maintain an amplified downlink signal below another predetermined limit. For example, after receiving a downlink signal from the base station via the second antenna, the level of the downlink signal is measured. A determination is made as to whether an amplified downlink signal will exceed the predetermined limit for the downlink signal. If the predetermined limit will be exceeded, the second amplification factor is adjusted such that the amplified downlink signal level remains below the predetermined liniit. The downlink signal is amplified using the resultant amplification factor, and the adjusted downlink signal is transmitted to the handset via the first antenna.

10971 ht one embodiment, the amplilication factors applied to the uplink and downlink signals arc controlled independently fi-om one another. For example, the ampliification factor applied to the downlink signal niay be allowed to exceed the amplification factor applied to the uplink signal. Similarly, the predetermined power limit of the amplified downlink signal may be established at a liigher level than the predetermined power linZit of the uplink signal.

[0981 Embodiments herein may comprise a special purpose or general-purpose computer including various computer harclware. Embodiments may also include computer-readable media for cari-ying or having computcr-executable insti-uctions or data str-uctures stot-ed tlier-eon. Such computer-rcadable media can he any available media tliat can be accessed by a general purpose oi- special purpose computer. By way of example, and not limitation, such computer-reaclable media can comprise RAM, ROM, EEPROM, C D-RON/I or otlier optical disk storage, magnctic disk storage or other magnetic: storage devices, or any otllei- medium wllich can be used to cari-y or store desired program code means in the form of computer-executable instructions or data structures and which can he accessed by a general purpose or special purpose computer. When -Pagc33-information is transferred or provided over a network or another communications connection (either hardwired, wireless, or a combination of hardwired and wireless) to a computer, the computer properly views the connection as a computer-readable medium. Thus, any such connection is properly termed a cornputer-readable medium. Combinations of the above should also be included within the scope of computer-readable media.

[0991 Computer-executable instructions comprise, for example, instructions and data which cause a general purpose computer, special purpose coinputer, or special purpose processing device to perform a certain function or group of functions. Although the subject matter has been described in language specific to sti-uctural features and/or methodological acts, it is to be understood that the subject matter defined in the appended claims is not necessarily liinited to the specitic features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of irnplementing the claims.

101001 The present invention niay be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims ratller than by the foregoing description. All changes which come within the meaning and 1-ange of equivalency of the claims are to be embraced within their scope.

- Pagc 34 -

Claims (28)

1. A network amplifier, comprising:

a first variable gain module having an input configured to receive an uplink signal from a handset and configured to apply a first amplification factor to the uplink signal to generate an adjusted uplink signal to be transmitted to a base station;

a first detector configured to detect a level of the uplink signal;

a gain control module configured to control the first amplification factor of the first variable gain module for limiting the output of the first variable gain module to ensure that the level of the adjusted uplink signal does not exceed a first predetermined level;

a first antenna coupled to an output of the first variable gain module and configured to transmit the adjusted uplink signal to the base station; and wherein the network amplifier is operable to ensure that, for each of a plurality of uplink signals having different respective attenuations, a corresponding adjusted uplink signal is generated that is less than the first predetermined level.

2. The network amplifier as recited in claim 1, wherein the first antenna is further configured to receive a downlink signal from the base station, further comprising:

a second gain module having an input coupled to the first antenna, the second gain module configured to apply a second amplification factor to the downlink signal, thereby generating an adjusted downlink signal to be communicated to the handset.

3. The network amplifier as recited in claim 2, further comprising:
a second detector for detecting a level of the downlink signal;

wherein the second gain module is a second variable gain module and is coupled to the gain control module, the gain control module further configured to ensure that the level of the adjusted downlink signal does not exceed a second predetermined level.

4. The network amplifier as recited in claim 3, wherein the first and second amplification factors are controlled independently from one another by the gain control module.

5. The network amplifier as recited in claim 4, wherein the first amplification factor is allowed to exceed the second amplification factor, and the first predetermined level is established at a higher level than the second predetermined level.

6. The network amplifier as recited in claim 1, wherein the uplink signal is received from the handset via a second antenna.

7. The network amplifier as recited in claim 1, wherein the gain controller reduces the first amplification factor in predetermined increments as the level of the uplink signal increases in order to maintain the level of the adjusted uplink signal below the first predetermined level.

8. A network amplifier, comprising:

a first antenna configured to receive an uplink signal from a handset;
a first detector for detecting a level of the uplink signal;

a first gain module configured to apply a first amplification factor to the uplink signal to generate an adjusted uplink signal, the first gain module comprising:

a first amplifier configured to amplify the uplink signal; and a first multistage attenuator configured to attenuate the uplink signal by progressively activating stages of attenuation as the level of the uplink signal increases in order to maintain the adjusted uplink signal level below a first predetermined level, wherein the first amplification factor equals a combined effect of the first amplifier and the first multistage attenuator; and a second antenna coupled to an output of the first gain module and configured to transmit the adjusted uplink signal to a base station.

9. The network amplifier as recited in claim 8, wherein the second antenna is further configured to receive a downlink signal from the base station, further comprising:

a second gain module having an input coupled to the second antenna, the second gain module configured to apply a second amplification factor to the downlink signal, thereby generating an adjusted downlink signal to be communicated to the handset via the first antenna.

10. The network amplifier as recited in claim 9, further comprising:

a second detector for detecting a level of the downlink signal; and a second multistage attenuator configured to attenuate the downlink signal by progressively activating stages of attenuation as the level of the downlink signal increases in order to maintain the adjusted downlink signal level below a second predetermined level.

11. The network amplifier as recited in claim 10, wherein the stages of attenuation of the first and second multistage attenuators are controlled independently from one another.

12. The network amplifier as recited in claim 11, wherein the second amplification factor is allowed to exceed the first amplification factor, and the second predetermined level is established at a higher level than the first predetermined level.

13. The network amplifier as recited in claim 8, wherein a value of the first amplification factor is selected from a plurality of predefined amplification values.

14. The network amplifier as recited in claim 8, further comprising a gain control module configured to receive a signal level from the detector and control the stages of attenuation of the multistage attenuator.

15. In a network amplifier, one or more computer readable media having stored thereon computer executable instructions that, when executed by a processor, can cause the network amplifier to perform a method for variably amplifying a signal, the method comprising:
receiving an uplink signal from a handset via a first antenna;

measuring a level of the uplink signal;

determining if amplifying the uplink signal using a first amplification factor generates an adjusted uplink signal having a level that exceeds a first predetermined level;

adjusting the amplification factor if the adjusted uplink signal level exceeds the first predetermined level such that the adjusted uplink signal level remains below the first predetermined level;

amplifying the uplink signal using the resultant first amplification factor to generate the adjusted uplink signal; and transmitting the adjusted uplink signal to a base station via a second antenna; and wherein, for each of a plurality of uplink signals having different respective attenuations, a corresponding adjusted uplink signal is generated that is less than the first predetermined level.

16. The method as recited in claim 15, further comprising:

receiving a downlink signal from the base station via the second antenna;
measuring a level of the downlink signal;

determining if amplifying the downlink using a second amplification factor generates an adjusted downlink signal having a level that exceeds a second predetermined level;

adjusting the second amplification factor in the event that the adjusted downlink signal level exceeds the second predetermined level such that the adjusted downlink signal level remains below the second predetermined level;

amplifying the downlink signal using the resultant second amplification factor to generate the adjusted downlink signal; and transmitting the adjusted downlink signal to the handset via the first antenna.

17. The method as recited in claim 16, further comprising controlling the first and second amplification factors independently from one another.

18. The network amplifier as recited in claim 17, wherein the second amplification factor is allowed to exceed the first amplification factor, and the second predetermined level is established at a higher level than the first predetermined level.

19. The network amplifier as recited in claim 15, wherein adjusting the first amplification factor if the adjusted uplink signal level exceeds the first predetermined level such that the adjusted uplink signal level remains below the first predetermined level further comprises progressively activating stages of attenuation as the level of the uplink signal increases.

20. The network amplifier as recited in claim 15, wherein measuring a level of the uplink signal further comprises measuring the level of the adjusted uplink signal to determine if it exceeds the first predetermined level.

21. A wireless communication device that includes the network amplifier of claim 1.

22. The wireless communication device of claim 21, wherein the wireless communication device comprises one of a cell phone, a personal digital assistant, or a laptop computer.

23. A wireless communication device that includes the network amplifier of claim 8.

24. The wireless communication device of claim 23, wherein the wireless communication device comprises one of a cell phone, a personal digital assistant, or a laptop computer.

25. A wireless communication device in which the method of claim 15 is performed.

26. The wireless communication device of claim 25, wherein the wireless communication device comprises one of a cell phone, a personal digital assistant, or a laptop computer.

27. The network amplifier as recited in claim 1, wherein the value of the first amplification factor is a function of an extent to which the uplink signal has been attenuated during transmission of the uplink signal between the handset and the network amplifier.

28. The method as recited in claim 15, wherein the value of the first amplification factor is a function of an extent to which the uplink signal has been attenuated during transmission of the uplink signal between the handset and the network amplifier.