WO2000025445A1 - Method and apparatus for calibration of a wireless transmitter - Google Patents
Method and apparatus for calibration of a wireless transmitter Download PDFInfo
- Publication number
- WO2000025445A1 WO2000025445A1 PCT/US1999/025167 US9925167W WO0025445A1 WO 2000025445 A1 WO2000025445 A1 WO 2000025445A1 US 9925167 W US9925167 W US 9925167W WO 0025445 A1 WO0025445 A1 WO 0025445A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- level
- signal
- circuit element
- power level
- signal power
- Prior art date
Links
- 238000000034 method Methods 0.000 title claims abstract description 47
- 230000005540 biological transmission Effects 0.000 claims abstract description 48
- 230000006835 compression Effects 0.000 claims abstract description 22
- 238000007906 compression Methods 0.000 claims abstract description 22
- 230000008859 change Effects 0.000 claims abstract description 10
- 230000004044 response Effects 0.000 claims description 23
- 238000004891 communication Methods 0.000 claims description 22
- 230000003247 decreasing effect Effects 0.000 claims description 13
- 238000012935 Averaging Methods 0.000 claims description 3
- 230000003213 activating effect Effects 0.000 claims 1
- 230000008569 process Effects 0.000 abstract description 25
- 230000008901 benefit Effects 0.000 description 12
- 230000007423 decrease Effects 0.000 description 11
- 238000005259 measurement Methods 0.000 description 11
- 229920006395 saturated elastomer Polymers 0.000 description 8
- 230000032683 aging Effects 0.000 description 7
- 230000007274 generation of a signal involved in cell-cell signaling Effects 0.000 description 7
- 238000012360 testing method Methods 0.000 description 7
- 238000010586 diagram Methods 0.000 description 6
- 238000012545 processing Methods 0.000 description 5
- 238000001228 spectrum Methods 0.000 description 5
- 238000013461 design Methods 0.000 description 4
- 230000006870 function Effects 0.000 description 4
- 230000003595 spectral effect Effects 0.000 description 4
- 238000009826 distribution Methods 0.000 description 3
- 230000007246 mechanism Effects 0.000 description 3
- 238000013139 quantization Methods 0.000 description 3
- 230000002411 adverse Effects 0.000 description 2
- 230000007613 environmental effect Effects 0.000 description 2
- 238000012546 transfer Methods 0.000 description 2
- 230000001413 cellular effect Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000002431 foraging effect Effects 0.000 description 1
- 230000017525 heat dissipation Effects 0.000 description 1
- 230000000977 initiatory effect Effects 0.000 description 1
- 238000003780 insertion Methods 0.000 description 1
- 230000037431 insertion Effects 0.000 description 1
- 230000013011 mating Effects 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 230000001960 triggered effect Effects 0.000 description 1
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
- 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
- H03G3/3047—Automatic control in amplifiers having semiconductor devices in high-frequency amplifiers or in frequency-changers in modulators, frequency-changers, transmitters or power amplifiers for intermittent signals, e.g. burst signals
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B17/00—Monitoring; Testing
- H04B17/10—Monitoring; Testing of transmitters
- H04B17/11—Monitoring; Testing of transmitters for calibration
- H04B17/13—Monitoring; Testing of transmitters for calibration of power amplifiers, e.g. gain or non-linearity
-
- 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
- H04W52/30—TPC using constraints in the total amount of available transmission power
- H04W52/36—TPC using constraints in the total amount of available transmission power with a discrete range or set of values, e.g. step size, ramping or offsets
Definitions
- This invention relates generally to wireless transmitters. More specifically, the invention relates to power control in a wireless transmitter.
- Channelization can be achieved by one of a variety of well-known techniques such as time division multiple access (TDMA), code division multiple access (CDMA), frequency division multiple access (FDMA) or a combination of these.
- TDMA time division multiple access
- CDMA code division multiple access
- FDMA frequency division multiple access
- Each of these channelization techniques limits the frequency bandwidth of the signal transmitted from the remote unit.
- each of these channelization techniques requires the use of power control to some extent to determine the power level at which the remote unit transmits. If the remote unit signal arrives at the hub station at a signal level that is too low, the system performance level may be inadequate to support communication due to excessive errors caused by thermal noise and interference. If the remote unit signal arrives at the hub station at a signal level that is too high, the remote unit generates unnecessary interference to other system users.
- FIG. 1 is a schematic diagram illustrating a wireless satellite communication system.
- a hub station 10 provides digital data transfer capabilities to a plurality of remote units such as a remote unit 14.
- the hub station sends signals over an uplink forward channel 20 to a satellite 12.
- the satellite 12 repeats the signal and transmits it over a downlink forward channel 22.
- the remote unit 14 receives the signal and processes it.
- the remote unit 14 sends a signal over an uplink reverse channel 24 to the satellite 12.
- the satellite 12 repeats the signal and forwards it over a downlink reverse channel 26.
- a link budget is a design tool used to determine the level at which signals are transmitted over the system. For example, a link budget is used to determine a nominal level at which the remote unit 14 transmits the reverse link signal over the uplink reverse channel 24 based upon the expected path loss experienced over the uplink reverse channel 24.
- the satellite 12 may amplify the signal before forwarding it over the downlink reverse channel 26.
- the link budget estimates the expected path loss of the uplink and downlink reverse channels 24 and 26.
- the link budget estimates the expected interference and noise levels introduced by the uplink and downlink reverse channels 24 and 26 as well as noise introduced by the satellite 12 and the hub station 10 such as due to the noise figure of these units.
- the link budget estimates the expected variations of these parameters. Using the link budget, a system designer determines a nominal and worst case power level at which the remote unit transmits.
- the path loss of the wireless link channel is fairly consistent over time.
- weather conditions may vary the path loss to some extent.
- adverse weather conditions such as heavy fog, snow, rain or hail, may increase the path loss by several decibels (dB) or more. Therefore, in order to operate efficiently, most wireless systems include a power control loop to control the level at which signals are transmitted and received in the system.
- the hub station 10 monitors the signal-to-noise ratio of a signal received from the remote unit 14 over the reverse link channels 24 and 26 and notifies the remote unit 14 if the signal-to-noise ratio of the signal falls below a predetermined level.
- the remote unit 14 increases the power level at which it is transmitting. If the hub station 10 determines that the path loss has decreased, the hub station notifies the remote unit 14 over the forward link channels 20 and 22 and the remote unit 14 decreases the level at which it is transmitting.
- the remote unit 14 is typically designed to comprise a class A power amplifier. Class A power amplifiers provide a high degree of linearity over a substantial range of output power. In order to operate linearly, class A amplifiers require substantially more supply power than the power level of the radio frequency (RF) signals which they produce. A class A amplifier draws the same supply power regardless of the output power which it is producing.
- RF radio frequency
- FIG. 2 is a graph showing the characteristics of a typical class A amplifier. The horizontal axis represents the RF input power level in units of decibels referred to 1 milliwatt (dBm).
- the vertical axis represents the RF output power level of the amplifier in the same units.
- the gain of the amplifier illustrated by curve 32 is approximately 54 dB.
- the output power is 24 dBm.
- the output level also increases in 1 dB steps as is characteristic of a linear amplifier.
- the output power stops tracking the input power on a one-to-one basis.
- data point 36 on curve 32 represents the point at room temperature at which the gain of the amplifier has decreased by approximately 1 dB to 53 dB of gain.
- the input to the amplifier is approximately -19.5 dBm and the output is approximately 33.5 dBm.
- the output of the amplifier does not increase significantly above 34 dBm.
- Figure 3 is a spectrum plot showing the distortion caused when a modulated signal is amplified by a power amplifier which has the characteristics shown by curve 32 of Figure 2.
- the horizontal axis represents frequency and the vertical axis represents power level relative to the power level of the modulated signal.
- the horizontal axis is measured in terms of channels.
- Channel 1 represents the channel in which the remote unit is operating.
- Channels 2-8 correspond to other channels in the system.
- the spectrum plot shown in Figure 3 is a single side-band plot. However, it may be assumed that the spectrum created is relatively symmetric about the left-most axis as shown in Figure
- Curve 40 represents the spectrum output by the power amplifier when the modulated drive level is -30 dBm. Referring again to Figure 2, one can see that the power amplifier is quite linear in this region.
- the modulation bandwidth is limited to less than the bandwidth of the first channel.
- the modulated signal introduces some interference to adjacent channels. For example, in channel 2, the interference level generated is at least 35 dB lower than the intended signal level in channel 1. The interference level continues to drop in channels 3-8.
- Curve 42 represents the output of the power amplifier when the input power level is - 20 dBm. Referring again to Figure 2, one can see that operating at -20 dBm is approaching operation at the 1 dB compression point and the amplifier has begun to exhibit increased non- linearity. Due to the non-linearities, the interference level generated by the power amplifier in channel 2 has increased by approximately 10 dB. In addition, the interference level generated in channels 3-8 has also increased. Curves 46, 48, 50, 52 and 54 represent the output of the power amplifier when the input power level is -18, -14, -10, 0 and 10 dBm, respectively. As the input power level increases, the non-linearities continue to increase causing a corresponding increase in the interference level in the adjacent channels. Referring again to Figure 2, it can be seen that increasing the drive level does not significantly increase the output level once the 1 dB compression point has been reached. For these reasons, it is advantageous to limit the input power level such that the amplifier is operated in the linear region.
- curve 30 of Figure 2 represents the characteristics of the class A amplifier at a relatively high operating temperature. Notice that the 1 dB compression point has fallen to approximately -22 dBm of input power and 31 dBm of output power.
- curve 34 represents the characteristics of the amplifier significantly below room temperature.
- the 1 dB compression point has increased slightly with comparison to curve 32. Similar curves could be generated to represent the frequency and aging response of the amplifier.
- FIG 4 is a graph showing typical variations in operating curves of amplifiers constructed from a common process.
- Curve 32 represents the average performance at room temperature as also shown in Figure 2.
- Curve 60 represents a power amplifier which exhibits the one-sigma low side process variation characteristics. Notice that the 1 dB compression point is approximately -23 dBm and that the maximum output power of the amplifier is approximately 2 dB less than shown in curve 32. Also note that the gain of the amplifier represented by curve 60 is lower than shown in curve 32 even in the linear region.
- the curve 64 represents a power amplifier which exhibits the one-sigma high side process variation.
- the 1 dB compression point is approximately -19 dBm and that the gain of the amplifier is higher than the other two curves shown even in the linear region.
- the maximum output power must be limited in view of the worse case 1 dB compression point over all of these factors. Therefore, referring again to curve 60 of Figure 4, according to the prior art, the maximum output power of the system should be limited to approximately 29 dBm in order to accommodate variations over frequency, temperature and aging of the one sigma low side power amplifier.
- each remote unit's output power is limited according to the worse-case scenario.
- Typical prior art remote units use a detector to sense the output power level. When the output power level exceeds the predetermined maximum, the detector alerts the remote unit and the level at which the power amplifier is driven is limited to the current drive level. Because the output of the detector itself can vary according to process gains, frequency, temperature and aging, some margin must also be built into the system to accommodate for these variations. Alternatively, complicated detector calibration mechanisms can be incorporated into factory testing in order to account for some of these variations. In general, however, the maximum output power must be further limited in order to accommodate variations in the detector as well. In conjunction with the limitations imposed by the variations in the power amplifiers, these limitations significantly decrease the efficiency with which the average power amplifier is used during routine operation.
- routine operation is interrupted to enter a calibration mode.
- calibration mode the compression point of a circuit element is determined by applying a series of different drive levels to the circuit element.
- a maximum transmission point is selected for the remote unit.
- the remote unit uses the maximum transmission point to limit the signal power level transmitted over the wireless link. As time passes or operating conditions change, the calibration process is re-executed.
- Figure 1 is a schematic diagram illustrating a wireless satellite communication system.
- Figure 2 is a graph showing the characteristics of a typical class A amplifier.
- Figure 3 is a spectrum plot showing the distortion caused when a modulated signal is amplified by a power amplifier which has the characteristics shown by curve 32 of Figure 2.
- Figure 4 is a graph showing typical variations of operating curves produced by amplifiers constructed from a common process.
- Figure 5 is a block diagram showing an outdoor unit and an indoor unit of a remote unit in accordance with the invention.
- Figure 6 is a graph showing the characteristics of a typical schottky diode detector with respect to temperature.
- Figure 7 is a flow chart showing the process for calibration of transmission circuitry of an installed communication unit during routine operation.
- Figures 8 A through 8C are representational drawings illustrating the advantages that can be gained through transmission of a modulated signal.
- Figure 9 is a spectral plot showing a random access reverse link channel and a broadcast forward link channel.
- Figure 10 is a block diagram illustrating an exemplifying system in which the invention may be embodied.
- FIG. 5 is a block diagram showing an outdoor unit 68 and an indoor unit 90 of a remote unit in accordance with the invention.
- a satellite dish 70 is used to transmit and receive signals via a satellite transponder and is directly coupled to the outdoor unit 68.
- the outdoor unit 68 comprises circuit elements which are located in close proximity to the satellite dish 70.
- the satellite dish 70 is located on the roof of a building and the outdoor unit 68 is mounted directly to the satellite dish 70 assembly on the exterior of the building.
- the outdoor unit 64 comprises a low noise amplifier 74 which is located in close proximity to the satellite dish 70 in order to reduce the path loss between the satellite dish 70 and the low noise amplifier 74 and to preserve the system noise figure.
- the outdoor unit 68 comprises a power amplifier 82 which is located in close proximity to the satellite dish 70 in order to reduce the path loss between the power amplifier 82 and the satellite dish 70 and avoid increasing the required output of the power amplifier 82.
- the indoor unit 90 comprises circuitry which need not be located in close proximity to the satellite dish 70. In one embodiment, the indoor unit is located at a convenient position which allows more ready access by the system administrator.
- the indoor unit 90 is connected to the outdoor unit 68 by a length of cable.
- the division of the communication unit into the outdoor unit 68 and the indoor unit 90 allows them to be separately manufactured and factory tested.
- the outdoor unit 68 is preferably manufactured by an RF design house.
- the indoor unit 90 is preferably manufactured by a company which specializes in communications.
- the indoor unit 90 is designed to be compatible with a variety of different outdoor units which operate at a variety of different frequencies and which are manufactured by a variety of different vendors. When in place in the field, the outdoor unit and indoor unit can be separately serviced, replaced or upgraded.
- the satellite dish 70 is coupled to an orthomode transducer (OMT) 72 or other device or method for providing separation of signals.
- OMT orthomode transducer
- the OMT 72 couples the receive signals from the satellite dish 70 to the low noise amplifier 74.
- the OMT 72 also couples transmit signals from the power amplifier 82 to the satellite dish 70.
- the low noise amplifier 74 is coupled to a mixer 76 which down-converts the received signal to an intermediate frequency.
- the output of the mixer 76 is coupled to the indoor unit 90 via a length of cable.
- a receive processing unit 92 performs further analog and digital signal processing on the received signal.
- An indoor unit controller 98 controls the receive processing unit 92 as well as other components of the indoor unit 90.
- a signal generation unit 94 is controlled by the indoor unit controller 98 and creates the transmit signal waveform.
- the signal generation unit 94 receives data from system users and encodes the data for transmission.
- the signal generation unit 94 also modulates the encoded data, converts the modulated signal to an analog waveform and translates it to an intermediate frequency.
- the modulated IF output signal from the signal generation unit 94 is coupled to a variable gain amplifier 96.
- the gain of the variable gain amplifier 96 is controlled by the indoor unit controller 98.
- the output IF signal from the variable gain amplifier 96 is passed over a length of cable to the outdoor unit 68.
- a mixer 80 converts the IF signal to a RF frequency suitable for transmission.
- the RF center frequency is within the Ku band, Ka band or any other suitable band.
- the output of the mixer 80 is input into the power amplifier 82.
- the power amplifier 82 is a class A amplifier. When enabled, the power amplifier 82 outputs a high power RF signal to the satellite dish 70 via the OMT 72.
- the outdoor unit 68 comprises a detector 84, a microprocessor 86 and a temperature sensor 88.
- the microprocessor 86 is used to control the functions of the outdoor unit 68 and to provide information to the indoor unit controller 98.
- the microprocessor 86 is a low functionality part which does not greatly impact the price or size of the outdoor unit 68.
- the microprocessor 86 is an AT9054433 from Atmel Corporation of San Jose, CA.
- the microprocessor 86 is coupled to the indoor unit controller 98 and responds to commands therefrom. For example, the indoor unit controller 98 can request that the microprocessor 86 identify itself. In response, the microprocessor 86 forwards a unique identification number which uniquely identifies the outdoor unit 68. The identification can include, for example, the manufacturer, model, revision number, and capabilities of the outdoor unit 68.
- the microprocessor 86 comprises a 10-bit analog-to-digital (A/D) converter.
- the microprocessor 86 is coupled to the temperature sensor 88.
- the temperature sensor 88 outputs an analog signal level indicative of the operating temperature of the outdoor unit 86.
- the microprocessor 86 converts the analog temperature indication to a digital value using the analog-to-digital converter and provides the value to the indoor unit controller 98 upon request therefore.
- the power detector 84 is loosely coupled to the output of the power amplifier 82 such as through a coupler or power splitter.
- the power detector 84 is a schottky diode detector (or other detector-type) and outputs an analog signal level indicative of the RF signal power level produced by the power amplifier 82.
- Figure 6 is a graph showing the characteristics of a typical schottky diode detector over temperature. The vertical axis of Figure 6 is the detected output in volts. The horizontal axis is the amplitude of the RF input signal in volts.
- the curve 160 represents the response of the detector at -20C.
- the curve 162 represents the response of the detector at 25C.
- the curve 164 represents the response of the detector at +50C. As can be seen by Figure 6, the response of the detector is neither linear nor constant over temperature.
- the microprocessor 86 comprises an onboard oscillator which is used to create a clock by which data is transferred to the indoor unit 90.
- the onboard oscillator may cause undesirable in-band spurs in the transmit signal when operating.
- the on-board oscillator is disabled during normal transmissions and is enabled during the calibration process in order to convert the analog values to digital values. In addition, during periods of idleness, the oscillator is enabled for other functions.
- bursty data In a system which transfers digital data, remote units tend to generate bursty data.
- the bursty data is characterized in that it has a high peak-to-average traffic ratio, meaning that large blocks of data are transferred during short periods of time interposed between significantly longer periods of idleness.
- the reverse link resources are shared between a great number of remote units in the preferred embodiment. If the power amplifiers within the plurality of remote units remain active while the remote units are idle, the combined interference caused by the amplified noise from the idle remote units can create a significant amount of interference to the remote units which are currently transmitting. In order to decrease this interference, the power amplifiers in the idle remote units are disabled so that they do not amplify and transmit noise while idle.
- the microprocessor 86 is coupled to the power amplifier 82 such that it can disable the power amplifier during periods of idleness.
- the outdoor unit 68 has a fixed gain. The output power of the remote unit is varied by varying the input power to the outdoor unit 68.
- the variable gain amplifier 96 sets the output power of the indoor unit 90.
- the remote unit initially transmits at a relatively low signal level. Based upon a signal quality at which the reverse link signal reaches the hub station, the hub station sends commands over the forward link channel requesting the remote unit to increase the signal power level. When adverse weather conditions increase the path loss on the reverse link channel, the hub station sends a command over the forward link channel which orders an increase in signal power level transmitted by the remote unit.
- the indoor unit 90 increases the gain setting of the variable gain amplifier 96.
- the indoor unit comprises a memory unit 100 in which is stored a maximum gain setting for the variable gain amplifier 96.
- the hub station When the hub station sends a command for the remote unit to increase the signal power level at which it is transmitting, the message is received by the remote unit and processed by the receive processing unit 92. The command is forwarded to the indoor unit controller 98. In response, the indoor unit controller 98 increases the gain setting of the variable gain amplifier 96 unless the current gain setting is equal to or exceeds the maximum gain setting stored in the memory unit 100.
- the present invention comprises a means for determining the maximum gain setting such that the capabilities of the outdoor unit are fully exercised while avoiding non-linear operation.
- Figure 7 is a flow chart showing calibration of transmission circuitry of an installed communication unit during routine operation.
- Flow begins in start block 1 10.
- the outdoor unit 68 measures the current temperature using the temperature sensor 88.
- the microprocessor 86 converts the analog level to a digital value and forwards it to the indoor unit controller 96.
- the indoor unit controller 98 compares the temperature to a table of temperatures stored in the memory unit 100. If there is a valid maximum gain setting for this temperature stored in the memory unit 100, the indoor unit controller 98 uses the stored maximum gain setting in block 116 and flow continues back to block 112. If there is no valid maximum gain setting for the current temperature, flow continues in block 118.
- the indoor unit controller 98 interrupts routine operation and commands the signal generation unit 94 to generate a test sequence, thus, initiating the calibration sequence.
- the indoor unit controller 98 enables the power amplifier 82 and increases the gain setting of the variable gain amplifier 96 so that it produces a signal power level large enough to drive the power amplifier 82 deep into saturation. For example, referring again to Figure 4, the drive level to the power amplifier 82 exceeds -16 dBm such that both low performance and high performance parts are driven deep into saturation.
- the detector 84 measures the signal power level output by the power amplifier 82.
- the microprocessor 86 converts the analog detector value into a digital value and, then, passes it to the indoor unit controller 98.
- the indoor unit controller 98 decreases the gain setting of the variable gain amplifier 96 so that its output signal power level is decreased by some incremental amount. For example, the indoor unit controller 98 decreases the gain setting of the variable gain amplifier 96 to drop its output signal power level by approximately 1 dB.
- the detector 84 once again measures the output signal power level from the power amplifier 82. Once again, the microprocessor 86 digitizes the analog detector value and passes the value to the indoor unit controller 98.
- the indoor unit controller 98 compares the detected current signal power level to the saturated signal power level in block 128. If the current level is approximately equal to the saturated level, flow continues back to block 124. For example, if the current level plus two decibels is greater than the saturated level, flow continues back to block 124 and the signal power level produced by the variable gain amplifier 96 is further decreased. If the current value is less than the saturated level by some incremental amount, flow continues to block 130. In block 130 in the indoor unit controller 98 stores the current temperature and the current gain setting of the variable gain amplifier 96 in the memory unit 100. The stored value becomes the maximum gain setting corresponding to the current operating conditions.
- the steps shown in Figure 7 and described generally above are implemented in a series of processing units which are embodied in memory or custom application specific integrated circuits (ASIC) or executed by a microprocessor.
- the steps are implemented in software and executed, for example, by a digital signal processor (DSP) or embodied in hardware in a field programmable gate array (FPGA) or in an ASIC.
- DSP digital signal processor
- FPGA field programmable gate array
- variable gain amplifier 96 should be designed with enough gain "headroom” so that the variable gain amplifier 96 continues to linearly increase the driving signal level as the power amplifier 82 enters saturation.
- the detector 84 must have enough power handling capacity and linearity to provide accurate measurements as the power amplifier 82 enters saturation. Operation according to Figure 7 illustrates a specific implementation of the general principles of the invention.
- routine operation is interrupted to enter a calibration mode.
- calibration mode can be entered between transmission slots.
- a TDMA, FDMA or CDMA or other type of system calibration mode can be entered during a natural period of idleness which occurs between the transmission bursts.
- the calibration process can be executed over a series of disjoint periods of calibration.
- transmission of data can be interrupted or suspended in order to accommodate the calibration process.
- the remote unit continues to receive data from the wireless link during calibration mode.
- the compression point of a circuit element is determined by applying a series of different drive levels to the circuit element. Based upon the determination of the compression point, a maximum transmission point is selected for the remote unit. Upon resumption of normal operation, the remote unit uses the maximum transmission point to limit the signal power level transmitted over the wireless link. As time passes or operating conditions change, the calibration process is re-executed.
- the signal power level of an amplifier with the characteristics of curve 64 begins to decrease.
- the signal power level of an amplifier with the characteristics of curve 64 has dropped almost 1 decibel below the saturated level.
- the signal power level of a power amplifier with the characteristics of curve 32 has just begun to decrease from the saturated level.
- the signal power level produced by a power amplifier with the characteristics of the curve 60 remains nearly equal to the saturated level.
- the gain setting of the variable gain amplifier 96 is recorded as the maximum gain setting.
- the signal power level output by amplifiers with the characteristics of curve 32 and 60 also begins to fall.
- the maximum gain setting corresponding to curve 32 is approximately equal to -23 dBm and the maximum gain setting corresponding to curve 60 is approximately -24 dBm. In this way, each power amplifier can be used in accordance with its capabilities.
- the detector 84 does not have a perfectly linear response.
- the analog-to-digital converter within the microprocessor 86 introduces quantization errors when it converts the analog signal level to digital value. Therefore, some error is introduced by the accuracy with which the detector 84 measures the signal power level.
- the response of the variable gain amplifier 96 to changes in the gain setting is not perfectly linear and also introduces some error into the measurement. Therefore, it is advantageous to include some additional margin to compensate for any errors introduced by these factors.
- One advantage of operation according to the process of Figure 7 is that it is not necessary that the detector make an accurate and absolute determination of the signal power level output by the amplifier. It is only necessary that the detector measures a relative change in the output power. Likewise, the signal power level at which the variable gain amplifier 96 produces the IF drive signal need not be absolute. It is only necessary that the variable gain amplifier 96 output power change relative to the previous output level in response to the changing gain settings.
- additional factors which influence the outdoor unit characteristics are stored in the memory unit 100 in order to more precisely identify the current operating conditions.
- the data stored in the memory unit 100 is a function of both temperature and frequency or frequency band.
- the identification number of the outdoor unit is also stored in the memory unit 100. If a new outdoor unit is connected to the indoor unit, the calibration points must be retaken using the new outdoor unit.
- Other factors which can be considered in determining the current operating conditions are indoor unit temperature, the satellite or satellite position, the presence of rain or other environmental conditions or the rate of change of the temperature.
- FIGS 8A through 8C are representational drawings illustrating the advantages that can be gained through transmission of a modulated signal.
- CW constant wave
- the analog-to-digital converter within the microprocessor 86 converts the analog detector output to the closest digital value.
- Figure 8A a range of analog detector output voltages surrounding the level x is indicated. Any detector output within this range generates a digital value of x at the output of the analog-to-digital converter.
- any analog value between x - 1/2 and x + 1/2 maps into a value of x at the output of the analog-to-digital converter.
- Figure 8B if the detector output is x + 1/4, the output of the analog-to-digital converter is x. Error introduced in this manner is referred to as quantization error.
- Block 140 represents an even distribution of signal power levels produced by the power amplifier 82 centered about a value of x + 1/4 and fanning a range of plus or minus one analog-to-digital converter step size.
- Those detector level values which fall in the region below x - 1/2 as shown by the shaded region 142 map into a value of x - 1.
- Those detector level values which are between x - 1/2 and x + 1/2 map into the value x as shown by shaded region 144.
- 1/8 of the samples produce a value of x - 1
- one half of the samples produce a value of x
- 3/8 samples produce a value of x + 1.
- the average of these values is x + 1/4 which accurately reflects the average value of the signal power level.
- the remote units communicate with the hub station over the reverse link using a set of random access channels.
- the hub station communicates with the remote units on a broadcast channel.
- Figure 9 is a spectral plot showing a random access reverse link channel and a broadcast forward link channel.
- the random access reverse link channels 150A - 150N each originating from a different remote unit, randomly block one another in the natural course of system operation.
- the broadcast forward link channel 152 can be designed so that they do not block one another and, therefore, are more tolerant of additional interference.
- the forward link signals are typically sent at a higher power rate than the reverse link signals.
- the random access reverse link channels are typically transmitted about 10 dB lower power spectral density than the broadcast forward link channel.
- the hub station has a significantly larger antenna than the remote units and, therefore, it is able to detect the reverse link signal at a smaller power spectral density. Therefore, in one embodiment, when the calibration process is executed by the remote unit, the transmit frequency of the outdoor unit is changed so that the calibration output 154 falls within the forward link channel bandwidth. In this way, interference with the more susceptible random access reverse link channels 150A
- the output of the amplifier 82 during the calibration process is dumped into a dummy load so that a majority of the energy output by the power amplifier 82 is not transmitted over the wireless link.
- the remote unit transmits within the random access reverse link channels during the calibration process.
- the remote unit continues to transmit user data during the calibration process rather than a dummy sequence.
- the calibration process is triggered by changes in the operating temperature of the outdoor unit 68.
- the calibration values remain stored in the memory unit 100 and available for use should conditions return to a previously calibrated state.
- each calibration entry in the memory unit 100 is time-stamped and expires after a predetermined duration. After a set of stored values expires, the corresponding operating state characteristics are re-calibrated the next time such conditions exist.
- the current characteristics of the power amplifier are calibrated intermittently. In one embodiment, for example, the characteristics of the power amplifier is calibrated every eight minutes. The indoor unit uses the most recently collected data until the next calibration data is collected. This embodiment has the advantage of eliminating use of the temperature sensor. However, this embodiment requires more frequent calibration and is less accurate during periods of rapid temperature change.
- the invention has been described herein with reference to a satellite system. The same techniques can be applied to other operating environments.
- the invention can be implemented in a cellular or other terrestrial wireless communication system - either in the base station or remote unit.
- the invention can be implemented in systems which communicate using a variety of modulation and access techniques.
- the invention may be implemented in a FDMA, CDMA or TDMA type system.
- the description above was presented with reference to a power amplifier.
- teachings can be directly applied to calibrate of other types of circuit elements (such as mixers) or a set of circuit elements whether they exhibit class A, class AB, class B or other operating characteristics.
- the indoor unit controller 98 commands the signal generation unit 94 to forward a message to the hub station indicating that subsequent remote unit transmissions will have a decreased data rate.
- the indoor unit controller 98 commands the signal generation unit 94 to generate a message for the hub station indicating that subsequent transmissions from the remote unit will have an increased data rate.
- the compression point of the power amplifier 82 is determined by initially driving the power amplifier into saturation and, then, incrementally dropping the input drive level until the amplifier comes out of saturation.
- the 1 dB compression point is determined by incrementally increasing the drive level and detecting a decrease in the gain of the power amplifier 92 as it enters saturation.
- the power amplifier is driven at -26 dBm.
- a corresponding measurement is taken by the detector 84.
- the indoor unit controller 98 commands the variable gain amplifier 86 to increase its gain by approximately 1 dB.
- the detector 84 is used to make a measurement of the output power.
- the 1 dB compression point of the power amplifier 82 is determined when the measured signal power level indicates that the gain of the power amplifier 82 has fallen by 1 dB in comparison to the first measurement which is taken.
- the invention introduces a number of benefits into the system.
- the modular nature of the indoor unit and the outdoor unit allow them to be separately built, tested and calibrated and also separately serviced and replaced in the field.
- the invention it is not necessary that the invention be embodied in two separate units.
- the advantages of the invention will also benefit a system which is housed in a single body.
- each unit takes advantage of its full operating capabilities at the current operating conditions.
- the system does not require the measurement of an absolute signal power level which can be difficult and inaccurate.
- the invention allows certain changes to be automatically compensated for in the field. For example, if the length of cable which connects the indoor and outdoor units is increased in length, the insertion loss of the cable typically increases. Such changes are automatically accounted for during the next calibration process.
- the invention also has advantages in comparison with factory calibration.
- Factory calibration only calibrates for conditions as they exist in the calibration test set up. Such testing requires the fixed mating of indoor and outdoor units as well as the cables which connect them.
- factory calibration can be conducted over a variety of temperatures and frequencies, factory testing does not account for aging.
- factory testing does not account for environmental factors to which the unit may be subjected. For example, the impedance match between the outdoor unit and the satellite dish to which it is connected can affect the signal power level produced by the outdoor units. It is typically not practical to factory test a unit in conjunction with a satellite dish with which it is permanent coupled.
- Figure 10 is a block diagram illustrating an exemplifying system in which the invention may be embodied.
- the system in Figure 10 provides high-speed, reliable Internet communication service over a satellite link.
- content servers 200 are coupled to the Internet 202 which is in turn coupled to a hub station 204 such that the hub station 204 can request and receive digital data from the content servers 200.
- the hub station 204 also communicates via satellite 206 with a plurality of remote units 208A - 208N.
- the hub station 204 transmits signals over a forward uplink 210 to the satellite 206.
- the satellite 206 receives the signals from the forward uplink 210 and re-transmits them on a forward downlink 212.
- the forward uplink 210 and the forward downlink 212 are referred to as the forward link.
- the remote units 208A - 208N monitor one or more channels which comprise the forward link in order to receive remote-unit-specific and broadcast messages from the hub station 204.
- the remote units 208A - 208N transmit signals over a reverse uplink 214 to the satellite 206.
- the satellite 206 receives the signals from the reverse uplink 214 and re-transmits them on a reverse downlink 216.
- the reverse uplink 214 and the reverse downlink 216 are referred to as the reverse link.
- the hub station 204 monitors one or more channels which comprise the reverse link in order to extract messages from the remote units 208A - 208N.
- the reverse link carries multiple access channels.
- each remote unit 208A -208N is coupled to a plurality of system users.
- the remote unit 208A is shown as coupled to a local area network 216 which in turn is coupled to a group of user terminals 218A - 218N.
- the user terminals 218A - 218N may be one of many types of local area network nodes such as a personal or network computer, a printer, digital meter reading equipment or the like.
- the remote unit 208 A forwards it to the appropriate user terminal 218 over the local area network 216.
- the user terminals 218A - 218N can transmit messages to the remote unit 208 A over the local area network 216.
- the remote units 208A - 208N provide Internet service to a plurality of users. For example, assume that the user terminal
- the user terminal 218A is a personal computer which executes browser software in order to access the World Wide Web.
- the user terminal 218A creates a request message according to well-known techniques.
- the user terminal 218A forwards the request message over the local area network 216 to the remote unit 208A, also using well-known techniques.
- the remote unit 208A creates and transmits a wireless link request over a channel within the reverse uplink 214 and the reverse downlink 216.
- the hub station 204 receives the wireless link request over the reverse link. Based upon the wireless link request, the hub station 204 passes a request message to the appropriate content server 200 over the Internet 202.
- the content server 200 forwards the requested page or object to the hub station 204 over the Internet 202.
- the hub station 204 receives the requested page or object and creates a wireless link response.
- the hub station transmits the wireless link response over a channel within the forward uplink 210 and forward downlink 212.
- the invention is used to determine the assigned data rate.
- the remote unit 208A receives the wireless link response and forwards a corresponding response message to the user terminal 218A over the local area network 216. In this way, a bi-directional link between the user terminal 218 A and the content servers 200 is established.
- the analog detector may be replaced with a detector which produces a digital output indication.
- the temperature sensor may also be replaced with a sensor which produces a digital output indication.
- these elements are coupled directly to the indoor unit controller.
- gain variation is achieved through the use of a variable attenuator which can be located in either the indoor unit or the outdoor unit.
Abstract
Description
Claims
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AU13250/00A AU1325000A (en) | 1998-10-28 | 1999-10-27 | Method and apparatus for calibration of a wireless transmitter |
Applications Claiming Priority (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US10595398P | 1998-10-28 | 1998-10-28 | |
US60/105,953 | 1998-10-28 | ||
US09/407,641 | 1999-09-28 | ||
US09/407,641 US6256483B1 (en) | 1998-10-28 | 1999-09-28 | Method and apparatus for calibration of a wireless transmitter |
Publications (2)
Publication Number | Publication Date |
---|---|
WO2000025445A1 true WO2000025445A1 (en) | 2000-05-04 |
WO2000025445A9 WO2000025445A9 (en) | 2000-10-26 |
Family
ID=26803137
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/US1999/025167 WO2000025445A1 (en) | 1998-10-28 | 1999-10-27 | Method and apparatus for calibration of a wireless transmitter |
Country Status (3)
Country | Link |
---|---|
US (2) | US6256483B1 (en) |
AU (1) | AU1325000A (en) |
WO (1) | WO2000025445A1 (en) |
Cited By (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2002075960A1 (en) | 2001-03-16 | 2002-09-26 | U.S. Monolithics, L.L.C. | System and method for uplink power control |
WO2003052968A1 (en) * | 2001-12-18 | 2003-06-26 | Intersil Americas Inc. | Transmit power control for multiple rate wireless communications |
EP1374446A1 (en) * | 2001-03-16 | 2004-01-02 | U.S. Monolithics, L.L.C. | System and method for uplink power control |
WO2004086638A2 (en) * | 2003-03-24 | 2004-10-07 | Advanced Digital Broadcast Ltd. | Method for calibration of a signal receiver |
US7010266B2 (en) | 2001-05-24 | 2006-03-07 | Viasat, Inc. | Power control systems and methods for use in satellite-based data communications systems |
ITRM20100406A1 (en) * | 2010-07-21 | 2012-01-22 | Sie Soc It Elettronica | PROCEDURE FOR AUTOMATIC CALIBRATION OF BROADBAND MICROWAVE MODULES |
WO2012106144A1 (en) * | 2011-02-02 | 2012-08-09 | Qualcomm Atheros, Inc. | Method and system for adjusting transmission power |
Families Citing this family (34)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6728520B2 (en) * | 1999-08-31 | 2004-04-27 | Qualcomm Incorporated | System and method for constant loop gain in a closed loop circuit |
US6487420B1 (en) * | 1999-10-15 | 2002-11-26 | Telefonaktiebolaget Lm Ericsson (Publ) | Adaptive rach power determination for mobile telecommunications user equipment unit |
US6731946B1 (en) * | 2000-11-22 | 2004-05-04 | Ensemble Communications | System and method for timing detector measurements in a wireless communication system |
JP4545921B2 (en) * | 2000-12-22 | 2010-09-15 | 株式会社日立国際電気 | Wireless communication device |
US6704579B2 (en) * | 2001-02-15 | 2004-03-09 | Ensemble Communications | System and method of automatically calibrating the gain for a distributed wireless communication system |
US6570529B2 (en) * | 2001-05-24 | 2003-05-27 | Lucent Technologies Inc. | Autonomous calibration of a wireless-global positioning system |
US6819938B2 (en) * | 2001-06-26 | 2004-11-16 | Qualcomm Incorporated | System and method for power control calibration and a wireless communication device |
US6642905B2 (en) * | 2001-12-21 | 2003-11-04 | The Boeing Company | Thermal-locate 5W(V) and 5W(H) SSPA's on back of reflector(s) |
US7079818B2 (en) * | 2002-02-12 | 2006-07-18 | Broadcom Corporation | Programmable mutlistage amplifier and radio applications thereof |
US20030184487A1 (en) * | 2002-03-27 | 2003-10-02 | Desargant Glenn J. | Reflector/feed antenna with reflector mounted waveguide diplexer-OMT |
US20040198261A1 (en) | 2002-06-28 | 2004-10-07 | Wei Xiong | Method of self-calibration in a wireless transmitter |
US7177606B2 (en) * | 2002-07-10 | 2007-02-13 | General Instrument Corporation | Control system for controlling an output signal power level of a wireless transmitter |
US7076201B2 (en) * | 2002-09-05 | 2006-07-11 | Xytrans, Inc. | Low cost VSAT MMIC transceiver with automatic power control |
US20040092185A1 (en) * | 2002-11-13 | 2004-05-13 | Grafe Timothy H. | Wipe material with nanofiber layer |
US20040137840A1 (en) * | 2003-01-15 | 2004-07-15 | La Chapelle Michael De | Bi-directional transponder apparatus and method of operation |
US7668512B2 (en) * | 2003-01-15 | 2010-02-23 | Avago Technologies Fiber Ip (Singapore) Pte. Ltd. | Transceiver with a test mode of operation |
US7228114B2 (en) * | 2003-05-21 | 2007-06-05 | Harris Stratex Networks Operating Corporation | Wide dynamic range power detection scheme |
US8483717B2 (en) | 2003-06-27 | 2013-07-09 | Qualcomm Incorporated | Local area network assisted positioning |
US7561851B2 (en) * | 2004-04-01 | 2009-07-14 | Harris Stratex Networks, Inc. | System and method for calibrating modules of a wide-range transceiver |
US7606535B2 (en) * | 2004-04-01 | 2009-10-20 | Harris Stratex Networks, Inc. | Modular wide-range transceiver |
KR100603763B1 (en) * | 2004-06-10 | 2006-07-24 | 삼성전자주식회사 | Apparatus for sensing temperature using RF signal with different frequency and method thereof |
US7400866B2 (en) * | 2005-01-14 | 2008-07-15 | General Instrument Corporation | Methods and apparatus for calibrating and controlling output power levels in a broadband communication system |
US8422982B2 (en) * | 2005-10-03 | 2013-04-16 | Raven Nc Llc | Method and apparatus for DC power management within multi-channel LNBF |
US8209727B2 (en) * | 2006-04-04 | 2012-06-26 | At&T Intellectual Property I, Lp | Method and apparatus for distributing signals |
EP2111697B1 (en) * | 2006-09-26 | 2016-09-21 | ViaSat, Inc. | Improved spot beam satellite systems |
US8064855B2 (en) * | 2006-10-25 | 2011-11-22 | Panasonic Corporation | Transmission power controller |
US9295003B2 (en) * | 2007-03-19 | 2016-03-22 | Apple Inc. | Resource allocation in a communication system |
US8699984B2 (en) * | 2008-02-25 | 2014-04-15 | Csr Technology Inc. | Adaptive noise figure control in a radio receiver |
US8165296B2 (en) * | 2008-05-27 | 2012-04-24 | Viasat, Inc. | Time of day encryption using TDMA timing |
KR101624907B1 (en) * | 2010-03-16 | 2016-06-08 | 삼성전자주식회사 | Apparatus and method for controlling transmit power of indoor base station in broadband wireless communication system |
JP5996559B2 (en) * | 2011-02-07 | 2016-09-21 | スカイワークス ソリューションズ,インコーポレイテッドSkyworks Solutions,Inc. | Apparatus and method for envelope tracking calibration |
WO2013030633A2 (en) * | 2011-09-02 | 2013-03-07 | Autotalks Ltd. | Remote antenna unit with external power control using a single control line |
KR101738730B1 (en) | 2013-04-23 | 2017-05-22 | 스카이워크스 솔루션즈, 인코포레이티드 | Apparatus and methods for envelope shaping in power amplifier systems |
US9712261B2 (en) | 2013-08-15 | 2017-07-18 | Silicon Laboratories Inc. | Apparatus and method of background temperature calibration |
Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO1986007216A1 (en) * | 1985-05-31 | 1986-12-04 | Hughes Aircraft Company | Rf input drive saturation control loop |
EP0473299A2 (en) * | 1990-08-30 | 1992-03-04 | Hughes Aircraft Company | Solid state power amplifier with dynamically adjusted operating point |
EP0735690A2 (en) * | 1995-03-29 | 1996-10-02 | Siemens Aktiengesellschaft | Circuit for controlling power of radio apparatuses |
WO1996033555A1 (en) * | 1995-04-21 | 1996-10-24 | Qualcomm Incorporated | Temperature compensated automatic gain control |
Family Cites Families (95)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4545061A (en) | 1962-09-28 | 1985-10-01 | Sylvania Electric Products Inc. | Synchronizing system |
US3611435A (en) | 1969-03-24 | 1971-10-05 | Itt | Satellite communication system |
US3818453A (en) | 1971-08-11 | 1974-06-18 | Communications Satellite Corp | Tdma satellite communications system |
US4355388A (en) | 1979-09-27 | 1982-10-19 | Communications Satellite Corporation | Microprogrammable TDMA terminal controller |
GB2108357B (en) | 1981-09-28 | 1985-08-14 | Nippon Telegraph & Telephone | Method for resolving collision in local network |
US4574378A (en) | 1982-06-14 | 1986-03-04 | Nec Corporation | Multiple access system and method |
IT1161466B (en) | 1983-01-21 | 1987-03-18 | Cselt Centro Studi Lab Telecom | BASIC BAND EQUIPMENT FOR EARTH STATIONS OF A SATELLITE TRANSMISSION SYSTEM WITH TIME DIVISION ACCESS |
US4868795A (en) | 1985-08-05 | 1989-09-19 | Terra Marine Engineering, Inc. | Power leveling telemetry system |
US4763325A (en) | 1985-09-04 | 1988-08-09 | Comsat Telesystems, Inc. | Demand assigned reformatting with an overflow area for time division multiple access communication |
US4736371A (en) | 1985-12-30 | 1988-04-05 | Nec Corporation | Satellite communications system with random multiple access and time slot reservation |
US4837786A (en) | 1986-08-07 | 1989-06-06 | Comstream Corporation | Technique for mitigating rain fading in a satellite communications system using quadrature phase shift keying |
US4774707A (en) | 1986-09-10 | 1988-09-27 | General Electric Company | Random access communication system with scheduled data transmission and asynchronous contention scheduling |
US4811200A (en) | 1987-05-12 | 1989-03-07 | Motorola, Inc. | Multiple microprocessor watchdog system |
US4841527A (en) | 1987-11-16 | 1989-06-20 | General Electric Company | Stabilization of random access packet CDMA networks |
US5012469A (en) | 1988-07-29 | 1991-04-30 | Karamvir Sardana | Adaptive hybrid multiple access protocols |
US5121387A (en) | 1988-08-26 | 1992-06-09 | Scientific Atlanta | Link utilization control mechanism for demand assignment satellite communications network |
US5172375A (en) | 1989-06-22 | 1992-12-15 | Nec Corporation | Multiple access satellite communication system for mini-earth station networks |
US5446756A (en) | 1990-03-19 | 1995-08-29 | Celsat America, Inc. | Integrated cellular communications system |
US5166929A (en) | 1990-06-18 | 1992-11-24 | Northern Telecom Limited | Multiple access protocol |
US5159592A (en) | 1990-10-29 | 1992-10-27 | International Business Machines Corporation | Network address management for a wired network supporting wireless communication to a plurality of mobile users |
US5216427A (en) | 1990-11-01 | 1993-06-01 | California Institute Of Technology | Land-mobile satellite communication system |
US5297144A (en) | 1991-01-22 | 1994-03-22 | Spectrix Corporation | Reservation-based polling protocol for a wireless data communications network |
US5239677A (en) | 1991-07-01 | 1993-08-24 | Motorola, Inc. | Method and apparatus for initiating communication on an assigned frequency |
US5276703A (en) | 1992-01-13 | 1994-01-04 | Windata, Inc. | Wireless local area network communications system |
US5345583A (en) | 1992-05-13 | 1994-09-06 | Scientific-Atlanta, Inc. | Method and apparatus for momentarily interrupting power to a microprocessor to clear a fault state |
JPH0629910A (en) | 1992-07-09 | 1994-02-04 | Nec Corp | Inter radio base station synchronization system |
JPH07107994B2 (en) | 1992-08-27 | 1995-11-15 | 日本電気株式会社 | Access method |
US5381443A (en) | 1992-10-02 | 1995-01-10 | Motorola Inc. | Method and apparatus for frequency hopping a signalling channel in a communication system |
SE500565C2 (en) | 1992-10-26 | 1994-07-18 | Ericsson Telefon Ab L M | Method of providing random access in a mobile radio system |
JPH0738613B2 (en) | 1993-03-30 | 1995-04-26 | 日本電気株式会社 | Complex data communication system and device used for this system |
US5384777A (en) | 1993-04-19 | 1995-01-24 | International Business Machines Corporation | Adaptive medium access control scheme for wireless LAN |
US5696903A (en) | 1993-05-11 | 1997-12-09 | Norand Corporation | Hierarchical communications system using microlink, data rate switching, frequency hopping and vehicular local area networking |
JP2556254B2 (en) | 1993-05-12 | 1996-11-20 | 日本電気株式会社 | Burst transmission timing control method |
FI933129A0 (en) | 1993-07-08 | 1993-07-08 | Nokia Mobile Phones Ltd | DATAOEVERFOERINGSFOERFARANDE FOER ETT DIGITALT CELLULAERT MOBILTELEFONSYSTEM OCH ETT DIGITALT CELLULAERT MOBILTELEFONSYSTEM |
JPH07115428A (en) | 1993-10-20 | 1995-05-02 | Hitachi Ltd | Remote power control system |
US5485464A (en) | 1993-10-21 | 1996-01-16 | Hughes Aircraft Company | Communication protocol for a high data rate satellite communication system |
US5490087A (en) | 1993-12-06 | 1996-02-06 | Motorola, Inc. | Radio channel access control |
US5539730A (en) | 1994-01-11 | 1996-07-23 | Ericsson Ge Mobile Communications Inc. | TDMA/FDMA/CDMA hybrid radio access methods |
US5677909A (en) | 1994-05-11 | 1997-10-14 | Spectrix Corporation | Apparatus for exchanging data between a central station and a plurality of wireless remote stations on a time divided commnication channel |
US5537397A (en) | 1994-06-07 | 1996-07-16 | Aloha Networks, Inc. | Spread aloha CDMA data communications |
US5704038A (en) | 1994-09-30 | 1997-12-30 | Itt Automotive Electrical Systems, Inc. | Power-on-reset and watchdog circuit and method |
DE69433872T2 (en) | 1994-10-26 | 2005-07-14 | International Business Machines Corp. | Medium access control scheme for wireless local area networks with interleaved variable length time division frames |
US5570355A (en) | 1994-11-17 | 1996-10-29 | Lucent Technologies Inc. | Method and apparatus enabling synchronous transfer mode and packet mode access for multiple services on a broadband communication network |
JP2856086B2 (en) | 1994-12-26 | 1999-02-10 | 日本電気株式会社 | Satellite channel access method |
US5638361A (en) | 1995-02-08 | 1997-06-10 | Stanford Telecommunications, Inc. | Frequency hopped return link with net entry channel for a satellite personal communications system |
US5586121A (en) | 1995-04-21 | 1996-12-17 | Hybrid Networks, Inc. | Asymmetric hybrid access system and method |
US5732328A (en) | 1995-04-25 | 1998-03-24 | Lucent Technologies Inc. | Method for power control in wireless networks for communicating multiple information classes |
US5651009A (en) | 1995-05-02 | 1997-07-22 | Motorola, Inc. | System and method for hybrid contention/polling protocol collision resolution using a depth first search technique |
CA2220345C (en) | 1995-05-08 | 2001-09-04 | Compuserve Incorporated | System for electronic messaging via wireless devices |
TW292365B (en) | 1995-05-31 | 1996-12-01 | Hitachi Ltd | Computer management system |
GB2301741A (en) | 1995-06-02 | 1996-12-11 | Dsc Communications | Establishing a Downlink Communication Path in a Wireless Communications System |
US5809093A (en) | 1995-06-02 | 1998-09-15 | Dsc Communications Corporation | Apparatus and method of frame aligning information in a wireless telecommunications system |
US5745485A (en) | 1995-06-19 | 1998-04-28 | Aloha Networks, Inc. | Dual code multiple access for wireless data networks |
US5638371A (en) | 1995-06-27 | 1997-06-10 | Nec Usa, Inc. | Multiservices medium access control protocol for wireless ATM system |
US5710982A (en) | 1995-06-29 | 1998-01-20 | Hughes Electronics | Power control for TDMA mobile satellite communication system |
US5790939A (en) | 1995-06-29 | 1998-08-04 | Hughes Electronics Corporation | Method and system of frame timing synchronization in TDMA based mobile satellite communication system |
JP3435908B2 (en) | 1995-07-05 | 2003-08-11 | 松下電器産業株式会社 | Digital wireless communication device |
US5678208A (en) | 1995-07-19 | 1997-10-14 | Motorola, Inc. | Transmission system |
US5706278A (en) | 1995-07-20 | 1998-01-06 | Raytheon Company | Deterministic network protocol |
US5541924A (en) | 1995-07-28 | 1996-07-30 | Motorola, Inc. | Method and device for channel contention and data transmission for packet-switched subscriber units in a communication system |
US5642354A (en) | 1995-09-01 | 1997-06-24 | Motorola, Inc. | Enhanced access burst in a wireless communication system |
US5615212A (en) | 1995-09-11 | 1997-03-25 | Motorola Inc. | Method, device and router for providing a contention-based reservation mechanism within a mini-slotted dynamic entry polling slot supporting multiple service classes |
US5768254A (en) | 1995-09-29 | 1998-06-16 | Lucent Technologies Inc. | Multiple access cellular communication with signal cancellation to reduce co-channel interference |
US5802061A (en) | 1995-10-19 | 1998-09-01 | Cabletron Systems, Inc. | Method and apparatus for network access control with implicit ranging and dynamically assigned time slots |
US5790533A (en) | 1995-10-27 | 1998-08-04 | Motorola, Inc. | Method and apparatus for adaptive RF power control of cable access units |
US5809414A (en) | 1995-11-22 | 1998-09-15 | Northern Telecom Limited | User out-of-range indication for digital wireless systems |
US5790551A (en) | 1995-11-28 | 1998-08-04 | At&T Wireless Services Inc. | Packet data transmission using dynamic channel assignment |
US5966636A (en) | 1995-11-29 | 1999-10-12 | Motorola, Inc. | Method and apparatus for multiple access over randomized slots with collision detection in a cable telephony system |
JPH09200164A (en) | 1996-01-19 | 1997-07-31 | Hitachi Denshi Ltd | Fdma transmitter-receiver |
US5915207A (en) | 1996-01-22 | 1999-06-22 | Hughes Electronics Corporation | Mobile and wireless information dissemination architecture and protocols |
US5822311A (en) | 1996-03-05 | 1998-10-13 | Ericsson Inc. | Random access scheme for mobile satellite communications |
US5734833A (en) | 1996-03-12 | 1998-03-31 | Hewlett-Packard Company | Shared communications channel with enhanced reservation and collision resolution protocols allows any subset of stations to transmit data after collision occured in contention slot |
US5673322A (en) | 1996-03-22 | 1997-09-30 | Bell Communications Research, Inc. | System and method for providing protocol translation and filtering to access the world wide web from wireless or low-bandwidth networks |
US5796726A (en) | 1996-04-08 | 1998-08-18 | Ericsson Inc. | Systems and methods for random access in time division multiple access satellite radiotelephone communications |
US5946602A (en) | 1996-04-11 | 1999-08-31 | Comsat Corporation | Reduction of queuing delays by multiple subgroup assignments |
US5910945A (en) | 1996-04-30 | 1999-06-08 | Trw Inc. | Method and apparatus for synchronizing communications in a satellite based telecommunications system |
US5809400A (en) | 1996-06-21 | 1998-09-15 | Lucent Technologies Inc. | Intermodulation performance enhancement by dynamically controlling RF amplifier current |
US5818887A (en) | 1996-07-26 | 1998-10-06 | Motorola, Inc. | Method for receiving a signal in a digital radio frequency communication system |
US5848064A (en) | 1996-08-07 | 1998-12-08 | Telxon Corporation | Wireless software upgrades with version control |
US5905719A (en) | 1996-09-19 | 1999-05-18 | Bell Communications Research, Inc. | Method and system for wireless internet access |
US5872820A (en) | 1996-09-30 | 1999-02-16 | Intel Corporation | Synchronization in TDMA systems in a non-realtime fashion |
US5909447A (en) | 1996-10-29 | 1999-06-01 | Stanford Telecommunications, Inc. | Class of low cross correlation palindromic synchronization sequences for time tracking in synchronous multiple access communication systems |
US5958018A (en) | 1996-10-30 | 1999-09-28 | Lucent Technologies Inc. | Wireless services data network translating mac address to asynchronous transfer mode (ATM) address |
US5926458A (en) | 1997-01-31 | 1999-07-20 | Bay Networks | Method and apparatus for servicing multiple queues |
US5963557A (en) | 1997-04-11 | 1999-10-05 | Eng; John W. | High capacity reservation multiple access network with multiple shared unidirectional paths |
US6075779A (en) | 1997-06-09 | 2000-06-13 | Lucent Technologies, Inc. | Random access channel congestion control for broadcast teleservice acknowledgment messages |
US5960001A (en) | 1997-06-19 | 1999-09-28 | Siemens Information And Communication Networks, Inc. | Apparatus and method for guaranteeing isochronous data flow on a CSMA/CD network |
US5966412A (en) | 1997-06-30 | 1999-10-12 | Thomson Consumer Electronics, Inc. | Apparatus and method for processing a Quadrature Amplitude Modulated (QAM) signal |
JPH1141643A (en) | 1997-07-04 | 1999-02-12 | Internatl Business Mach Corp <Ibm> | Radio information processing terminal and control method therefor |
US5959982A (en) | 1997-08-29 | 1999-09-28 | Adicom Wireless, Inc. | Method and apparatus for adapting a time division duplex timing device for propagation delay |
JP3061122B2 (en) | 1997-09-04 | 2000-07-10 | 日本電気株式会社 | Transmission control method |
US5940025A (en) * | 1997-09-15 | 1999-08-17 | Raytheon Company | Noise cancellation method and apparatus |
US6567416B1 (en) | 1997-10-14 | 2003-05-20 | Lucent Technologies Inc. | Method for access control in a multiple access system for communications networks |
US5862452A (en) | 1997-10-20 | 1999-01-19 | Motorola, Inc. | Method, access point device and peripheral devices for low complexity dynamic persistence mode for random access in a wireless communication system |
JPH11131633A (en) | 1997-11-01 | 1999-05-18 | Kamano Kensetsu Kk | Charcoal block |
-
1999
- 1999-09-28 US US09/407,641 patent/US6256483B1/en not_active Expired - Lifetime
- 1999-10-27 AU AU13250/00A patent/AU1325000A/en not_active Abandoned
- 1999-10-27 WO PCT/US1999/025167 patent/WO2000025445A1/en active Application Filing
-
2001
- 2001-05-17 US US09/860,035 patent/US20020037705A1/en not_active Abandoned
Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO1986007216A1 (en) * | 1985-05-31 | 1986-12-04 | Hughes Aircraft Company | Rf input drive saturation control loop |
EP0473299A2 (en) * | 1990-08-30 | 1992-03-04 | Hughes Aircraft Company | Solid state power amplifier with dynamically adjusted operating point |
EP0735690A2 (en) * | 1995-03-29 | 1996-10-02 | Siemens Aktiengesellschaft | Circuit for controlling power of radio apparatuses |
WO1996033555A1 (en) * | 1995-04-21 | 1996-10-24 | Qualcomm Incorporated | Temperature compensated automatic gain control |
Cited By (15)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP1374447A1 (en) * | 2001-03-16 | 2004-01-02 | U.S. Monolithics, L.L.C. | System and method for uplink power control |
EP1374446A1 (en) * | 2001-03-16 | 2004-01-02 | U.S. Monolithics, L.L.C. | System and method for uplink power control |
EP1374446A4 (en) * | 2001-03-16 | 2004-09-08 | Us Monolithics Llc | System and method for uplink power control |
WO2002075960A1 (en) | 2001-03-16 | 2002-09-26 | U.S. Monolithics, L.L.C. | System and method for uplink power control |
EP1374447A4 (en) * | 2001-03-16 | 2007-06-13 | Us Monolithics Llc | System and method for uplink power control |
US7010266B2 (en) | 2001-05-24 | 2006-03-07 | Viasat, Inc. | Power control systems and methods for use in satellite-based data communications systems |
WO2003052968A1 (en) * | 2001-12-18 | 2003-06-26 | Intersil Americas Inc. | Transmit power control for multiple rate wireless communications |
US6735420B2 (en) | 2001-12-18 | 2004-05-11 | Globespanvirata, Inc. | Transmit power control for multiple rate wireless communications |
WO2004086638A2 (en) * | 2003-03-24 | 2004-10-07 | Advanced Digital Broadcast Ltd. | Method for calibration of a signal receiver |
US7171172B2 (en) | 2003-03-24 | 2007-01-30 | Zylowski Sebastian | Method for calibration of a signal receiver |
WO2004086638A3 (en) * | 2003-03-24 | 2005-01-06 | Advanced Digital Broadcast Ltd | Method for calibration of a signal receiver |
ITRM20100406A1 (en) * | 2010-07-21 | 2012-01-22 | Sie Soc It Elettronica | PROCEDURE FOR AUTOMATIC CALIBRATION OF BROADBAND MICROWAVE MODULES |
WO2012011141A1 (en) * | 2010-07-21 | 2012-01-26 | Elettronica S.P.A. | Process for automatically calibrating wideband microwave modules" |
WO2012106144A1 (en) * | 2011-02-02 | 2012-08-09 | Qualcomm Atheros, Inc. | Method and system for adjusting transmission power |
US8489045B2 (en) | 2011-02-02 | 2013-07-16 | Qualcomm Incorporated | Method and system for adjusting transmission power |
Also Published As
Publication number | Publication date |
---|---|
US20020037705A1 (en) | 2002-03-28 |
WO2000025445A9 (en) | 2000-10-26 |
US6256483B1 (en) | 2001-07-03 |
AU1325000A (en) | 2000-05-15 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US6256483B1 (en) | Method and apparatus for calibration of a wireless transmitter | |
CN1666449B (en) | Transmitter and receiver gain calibration by means of feedback in a transceiver | |
EP1110310B1 (en) | System for improving the dynamic range of transmitter power measurement in a cellular telephone | |
CA1215745A (en) | Transmitter power control circuit | |
US6917823B2 (en) | Cellular telephone | |
EP1374446B1 (en) | System and method for uplink power control | |
RU2393637C2 (en) | Methods for self-calibration in wireless transmitter | |
US20090252255A1 (en) | Predistortion methods and apparatus for polar modulation transmitters | |
CN105027429A (en) | Et system with adjustment for noise | |
US8265581B2 (en) | Transceiver using millimeter-wave | |
US20090011730A1 (en) | Methods and Apparatus for Controlling Power in a Polar Modulation Transmitter | |
US8270916B2 (en) | Methods for tuning and controlling output power in polar transmitters | |
US20070270174A1 (en) | Antenna matching measurement and amplification control | |
US9166859B2 (en) | Wireless communication apparatus and transmission power control method | |
US7206591B2 (en) | Toneless telemetry in a wireless system | |
KR100431912B1 (en) | Base station transmitter and cdma mobile communication system comprising the same | |
US9363130B2 (en) | Dynamic digital predistortion for a microwave radio system | |
KR100641527B1 (en) | Method for adaptively controlling amplifier linearization devices | |
KR20030024285A (en) | Operating Point Determination Apparatus and method for High Power Amplifier of Communication and Broadcasting Satellite Transponder | |
US7289777B2 (en) | Power control for non-constant envelope modulation | |
US6904268B2 (en) | Low noise linear transmitter using cartesian feedback | |
US7653365B2 (en) | Method for controlling signal power in transmitter of radio system by weighting, and transmitter therefor | |
EP1463197B1 (en) | A device and method for measuring dependency of output power and for generating a ramp signal for a power amplifier | |
KR100700102B1 (en) | A Method For Maintaining PAR Of Digital Transceiver | |
KR102614853B1 (en) | A repeater for measuring isolation and a method for measuring the same |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
ENP | Entry into the national phase |
Ref country code: AU Ref document number: 2000 13250 Kind code of ref document: A Format of ref document f/p: F |
|
AK | Designated states |
Kind code of ref document: A1 Designated state(s): AE AL AM AT AU AZ BA BB BG BR BY CA CH CN CR CU CZ DE DK DM EE ES FI GB GD GE GH GM HR HU ID IL IN IS JP KE KG KP KR KZ LC LK LR LS LT LU LV MD MG MK MN MW MX NO NZ PL PT RO RU SD SE SG SI SK SL TJ TM TR TT TZ UA UG UZ VN YU ZA ZW |
|
AL | Designated countries for regional patents |
Kind code of ref document: A1 Designated state(s): GH GM KE LS MW SD SL SZ TZ UG ZW AM AZ BY KG KZ MD RU TJ TM AT BE CH CY DE DK ES FI FR GB GR IE IT LU MC NL PT SE BF BJ CF CG CI CM GA GN GW ML MR NE SN TD TG |
|
121 | Ep: the epo has been informed by wipo that ep was designated in this application | ||
DFPE | Request for preliminary examination filed prior to expiration of 19th month from priority date (pct application filed before 20040101) | ||
AK | Designated states |
Kind code of ref document: C2 Designated state(s): AE AL AM AT AU AZ BA BB BG BR BY CA CH CN CR CU CZ DE DK DM EE ES FI GB GD GE GH GM HR HU ID IL IN IS JP KE KG KP KR KZ LC LK LR LS LT LU LV MD MG MK MN MW MX NO NZ PL PT RO RU SD SE SG SI SK SL TJ TM TR TT TZ UA UG UZ VN YU ZA ZW |
|
AL | Designated countries for regional patents |
Kind code of ref document: C2 Designated state(s): GH GM KE LS MW SD SL SZ TZ UG ZW AM AZ BY KG KZ MD RU TJ TM AT BE CH CY DE DK ES FI FR GB GR IE IT LU MC NL PT SE BF BJ CF CG CI CM GA GN GW ML MR NE SN TD TG |
|
COP | Corrected version of pamphlet |
Free format text: PAGES 1/9-9/9, DRAWINGS, REPLACED BY NEW PAGES 1/10-10/10; DUE TO LATE TRANSMITTAL BY THE RECEIVINGOFFICE |
|
REG | Reference to national code |
Ref country code: DE Ref legal event code: 8642 |
|
122 | Ep: pct application non-entry in european phase |