Since the predistortion is not perfect, the power-amplifier output is sampled, downconverted, digitized, and fed back to a DSP. The DSP uses the output samples to compute new corrective compensations parameters for the Paladin chip. The predistortion is fine-tuned using the Adaptive Control Processor Compensation Estimator firmware running on the DSP to further reduce the final output distortion. This feedback also helps compensate for any other variations such as temperature, power-supply drift, mechanical shock, aging, and any other dynamic characteristic that can produce nonlinearities.
Terry Ngo, PMC-Sierra's product marketing engineer, indicates that using this system can considerably reduce basestation costs. Initial costs are significantly less, as the costly feed-forward amplifiers can be replaced by simpler, more efficient Class-AB linear power amplifiers. The resultant power savings is dramatic. Potentially, carriers can save megawatts and millions of dollars annually with this system. PMC-Sierra also recently announced its PM2360 reference design kit, which can be used to speed design time-to-market and lower development costs in new basestations for WCDMA and cdma2000.
Basestation design also is profiting from improved DSP chips. Doug Grant of Analog Devices says that the company's new TigerSharc DSP chip can potentially reduce basestation costs by up to 50%. The new ADSP-TS101S is now fast enough to process at CDMA chip rates of up to 4 Mbits/s, eliminating the need for fast special-purpose ASICs or FPGAs. Such an all-software solution fits well with the basestation's increasing need to deal with multiple radio standards and make future upgrades fast, easy, and inexpensive.
Texas Instruments (TI) is another company addressing the DSP needs of 3G radios. Its Open Media Applications Platform (OMAP), introduced over a year ago, has been adopted by many handset manufacturers and software vendors. OMAP provides a wide range of modem and baseband solutions for 2.5G and 3G phones. OMAP chips combine an enhanced ARM processor with one or two of TI's TMS32055x DSPs to perform modulation/demodulation and all baseband functions, regardless of the technology.
An example is TI's OMAP710 GSM/GPRS chip, which handles all functions for GPRS-enabled GSM 2.5G cell phones or PDAs. TI's marketing manager for its wireless components group, Richard Kerslake, reports that TI recently entered into a collaborative technology, product, and marketing agreement with Palm to provide OMAP hardware and software for Palm's future PDAs and other wireless products.
A PDA/cell-phone combo with a common keyboard and screen is a major new product category that will make suggested 3G applications possible. It may just end up being the 3G phone of choice.
In fact, PDAs and laptops are expected to compete with 3G phones for some data applications. PDAs now feature e-mail and Internet access. The same goes for laptops thanks to IEEE-802.11b wireless Ethernet developments. Wireless local-area network (LAN) ports are now showing up in many locations, such as airports, hotels, convention centers, and even restaurants and coffee shops.
Testing Poses A Major Challenge
The current status of 3G is clearly one of R&D and testing. Handset and basestation manufacturers are still developing products, and the carriers are busy testing and evaluating their performance. Test equipment is playing a major role in cellular phone systems. Testing 2.5G and 3G products involves many specific measurements to ensure compliance with current standards.
Agilent Technologies' variety of new test instruments and systems make testing and measurement much faster and easier. Agilent's new instruments automate these tests with single-button ease.
An example is the PSA II line of spectrum analyzers, which implement tests such as channel power, bandwidth, adjacent-channel power, harmonic distortion, third-order intercept, and others for multiple standards, including GSM/GPRS/EDGE, cdma2000, 3GPP WCDMA, and Bluetooth. The E4443A analyzer has a bandwidth of 6.7 GHz.
Agilent's E4438C Vector Signal Generator is designed to provide the signal inputs for testing handsets and basestations. Generating as high as 6-GHz signals, it supports all the major cell-phone standards, plus the Bluetooth and IEEE-802.11a and -802.11b wireless LAN standards.
Agilent's 8960 wireless communications test set combines a spectrum analyzer, a signal generator, and one-button operation for cell-phone production testing (Fig. 3). It supports all WCDMA, cdma2000, and 2G standards.
References
1. "Designers Face Tough Challenges In 3G Cell-Phone Specs," Louis E. Frenzel, Electronic Design, Oct. 2, 2000, p. 107.
2. "Driving Toward 3G Cell Phones: Are We There Yet?" Louis E. Frenzel, Electronic Design, Feb. 19, 2001, p. 113.
Since the predistortion is not perfect, the power-amplifier output is sampled, downconverted, digitized, and fed back to a DSP. The DSP uses the output samples to compute new corrective compensations parameters for the Paladin chip. The predistortion is fine-tuned using the Adaptive Control Processor Compensation Estimator firmware running on the DSP to further reduce the final output distortion. This feedback also helps compensate for any other variations such as temperature, power-supply drift, mechanical shock, aging, and any other dynamic characteristic that can produce nonlinearities.
Terry Ngo, PMC-Sierra's product marketing engineer, indicates that using this system can considerably reduce basestation costs. Initial costs are significantly less, as the costly feed-forward amplifiers can be replaced by simpler, more efficient Class-AB linear power amplifiers. The resultant power savings is dramatic. Potentially, carriers can save megawatts and millions of dollars annually with this system. PMC-Sierra also recently announced its PM2360 reference design kit, which can be used to speed design time-to-market and lower development costs in new basestations for WCDMA and cdma2000.
Basestation design also is profiting from improved DSP chips. Doug Grant of Analog Devices says that the company's new TigerSharc DSP chip can potentially reduce basestation costs by up to 50%. The new ADSP-TS101S is now fast enough to process at CDMA chip rates of up to 4 Mbits/s, eliminating the need for fast special-purpose ASICs or FPGAs. Such an all-software solution fits well with the basestation's increasing need to deal with multiple radio standards and make future upgrades fast, easy, and inexpensive.
Texas Instruments (TI) is another company addressing the DSP needs of 3G radios. Its Open Media Applications Platform (OMAP), introduced over a year ago, has been adopted by many handset manufacturers and software vendors. OMAP provides a wide range of modem and baseband solutions for 2.5G and 3G phones. OMAP chips combine an enhanced ARM processor with one or two of TI's TMS32055x DSPs to perform modulation/demodulation and all baseband functions, regardless of the technology.
An example is TI's OMAP710 GSM/GPRS chip, which handles all functions for GPRS-enabled GSM 2.5G cell phones or PDAs. TI's marketing manager for its wireless components group, Richard Kerslake, reports that TI recently entered into a collaborative technology, product, and marketing agreement with Palm to provide OMAP hardware and software for Palm's future PDAs and other wireless products.
A PDA/cell-phone combo with a common keyboard and screen is a major new product category that will make suggested 3G applications possible. It may just end up being the 3G phone of choice.
In fact, PDAs and laptops are expected to compete with 3G phones for some data applications. PDAs now feature e-mail and Internet access. The same goes for laptops thanks to IEEE-802.11b wireless Ethernet developments. Wireless local-area network (LAN) ports are now showing up in many locations, such as airports, hotels, convention centers, and even restaurants and coffee shops.
Testing Poses A Major Challenge
The current status of 3G is clearly one of R&D and testing. Handset and basestation manufacturers are still developing products, and the carriers are busy testing and evaluating their performance. Test equipment is playing a major role in cellular phone systems. Testing 2.5G and 3G products involves many specific measurements to ensure compliance with current standards.
Agilent Technologies' variety of new test instruments and systems make testing and measurement much faster and easier. Agilent's new instruments automate these tests with single-button ease.
An example is the PSA II line of spectrum analyzers, which implement tests such as channel power, bandwidth, adjacent-channel power, harmonic distortion, third-order intercept, and others for multiple standards, including GSM/GPRS/EDGE, cdma2000, 3GPP WCDMA, and Bluetooth. The E4443A analyzer has a bandwidth of 6.7 GHz.
Agilent's E4438C Vector Signal Generator is designed to provide the signal inputs for testing handsets and basestations. Generating as high as 6-GHz signals, it supports all the major cell-phone standards, plus the Bluetooth and IEEE-802.11a and -802.11b wireless LAN standards.
Agilent's 8960 wireless communications test set combines a spectrum analyzer, a signal generator, and one-button operation for cell-phone production testing (Fig. 3). It supports all WCDMA, cdma2000, and 2G standards.
References
1. "Designers Face Tough Challenges In 3G Cell-Phone Specs," Louis E. Frenzel, Electronic Design, Oct. 2, 2000, p. 107.
2. "Driving Toward 3G Cell Phones: Are We There Yet?" Louis E. Frenzel, Electronic Design, Feb. 19, 2001, p. 113.