Technology and customer demand are intertwined in this and many other industries. Although it is often uncertain which of the two is driving the other, technology advancement is an essential part of the economic health of the high-frequency industry. As a review of some of the key RF/microwave technology areas will show, improvements in a wide range of device, component, and materials sciences are making tomorrow's products possible and today's products affordable.
Markets that are driving high-frequency technological enhancements include applications in commercial, military, industrial, medical, and automotive areas. Commercial communications, for example, continue to be driven by the growth of wireless devices and networks. And these networks must now provide more than just voice, as service providers whet their customers' appetites for multimedia services with package deals of voice, high-speed data, and even video over cellular telephones. The word "broadband" has come to mean more than just high-speed fixed Internet access as more and more service provides and network installers look to a future filled with mobile broadband wireless-access (BWA) communications devices.
Of course, the "holy grail" of broadband markets for the past decade has been the elusive "last mile" to the home. As copper-wired, optical, and wireless networks have expanded in terms of reach and broadband capabilities, "completion" of the network has hinged on delivering the widest communications pipe possible to each customer in order to support the greatest number of potential services. While AT&T, Verizon, and others have installed costly fiber-to-the-home (FTTH) last-mile solutions to provide their customers with extended services, many service providers have sought a broadband wireless alternative to that last mile, even exploring the use of millimeter-wave technology in the form of LMDS.
The final wireless solution, however, may lie in the form of WiMAX (www.wimax.com), an air interface originally conceived to provide printout fixed wireless communications at frequencies from 10 to 66 GHz. Although still experiencing the growing pains of standardization, the basis for a standard lies in the IEEE's 802.16 documentation and subsequent "a" through "e" work groups. The most recent work group (IEEE 802.16e) is establishing guidelines for the use of WiMAX air interfaces for mobile wireless applications employing orthogonal (OFDM) modulation.
Although the wireless-local-area network (WLAN) or Wi-Fi market was slow to gain momentum due to lack of standardization, it has prospered in spite of the number of variations on the original 802.11 standard proposal (such as IEEE 802.11a/b/g/n) and different operating frequencies. WLAN equipment suppliers have simply adapted as cellular suppliers have done, by developing multimode transceiver solutions to work across multiple standards.
The WiMAX market appears poised for explosive growth, given that major forces in communications equipment, such as Intel Corp. (www.intel.com) and Motorola (www.motorola.com) view that market as critical to their future growth. (Those interested in a well-written white paper comparing WLAN (Wi-Fi) and WiMAX can download a free copy of "Understanding Wi-Fi and WiMAX as Metro-Access Solutions" from the Intel website.) And, in spite of the large amount of publicity on the potential of WiMAX for broadband services from these companies and those involved in the WiMAX Forum (www.wimaxforum.org), an industry organization devoted to the growth of WiMAX products and technology, WiMAX may be ready for testing under real world conditions. Trials are under way on equipment conforming to the initial, fixed version of WiMAX (the IEEE 802.16-2004 standard) with the mobile version of the specification (IEEE 802.16e) close to finalization.
Early applications for WiMAX equipment are expected to be as back-haul connections for cellular base stations, for WLAN base stations, as replacements for enterprise T1 lines, and as alternatives to digital-subscriber-line (DSL) high-speed Internet service in rural and developing areas. The lure of WiMAX-based services will certainly be enticing for many service providers, given that they will soon be able to add wireless services without the investment in a cellular or PCS license.
As a hint of what may be to come, last month Korean Telecom (KT) launched their Wi-Bro mobile broadband wireless network based on the coming IEEE 802.16e WiMAX standard. KT (a WiMAX Forum member) was lauded by WiMAX Forum President Ron Resnick at last month's Asia-Pacific Economic Cooperation's (APEC) annual event (Busan, Korea), "KT's Wi-Bro services provide an early glimpse to what is possible and that mobile WiMAX will be the technology to deliver personal broadband to consumers around the globe." During APEC, and with the support of a variety of new Wi-Bro handsets manufactured by Samsung, KT held live demonstrations of the new network and its services, including Wonder-Media (video), Wonder-message (SMS, MMS), Wonder-Phone (mobile VoIP), and Wonder-Tour (location-based services delivered to PDAs, tablet personal computers, and laptop computers).
Of course, cellular operators will not sit idly waiting for WiMAX services to displace them. In order to enhance the reliability of Multimedia Broadcast/Multicast Service (MBMS) operation for third-generation (3G) cellular networks, the 3G Partnership Project (3GPP) has standardized on the use of patented DF Raptor forwarder (FEC) technology from Digital Fountain (www.digitalfountain.com). The DF Raptor technology supports both streaming and file downloading services for 3GPP 3G mobile telephones. The MBMS employs multicast and broadcast transmission for multimedia services so that multiple mobile devices can share common radio and network resources. The DF Raptor technology protects MBMS signals from packet loss, avoiding file and transmission degradation. According to Frederic Gabin, 3G Standards Project Leader at NEC, "Digital Fountain's FEC provides the best of both worlds: low bandwidth overhead, low processing requirements for client devices, and effective protection of MBMS file transfer and streaming services from packet loss over 3G wireless channels."
Cellular 3G designers also received a technological boost with the development of Peregrine Semiconductor's (www.peregrine-semi.com) HaRP? technology enhancements to the company's UltraCMOS process. The process upgrade leads to improved intermodulation-distortion (IMD) performance in several switch products, ultimately resulting in greater dynamic range in cellular networks. The firm's PE42672 single-pole, seven throw (SP7T) and PE42660 single pole, six-throw (SP6T) switches for quad-band GSM and GSM/WCDMA handset applications benefit from the new technology with third-order intercept points of better than +70 dBm at cellular frequencies. The UltraCMOS technology involves the fabrication of silicon CMOS devices on an insulating sapphire substrate, which is capable of handling high power levels. The HaRP enhancement improves the linearity of the devices when operating at high power levels.
In support of WiMAX designs the EEsof EDA Div. of Agilent Technologies (www.agilent.com) recently introduced a WiMAX design library for its ADS 2005A and RF Design Environment (RFDE) software environments. The library includes a wide range of analog, RF, and digital-signal-processing building blocks for constructing WiMAX systems. The design library also includes test benches for receiver sensitivity measurements, bit-error-rate (BER) measurements, and frame-error-rate (FER) measurements.
On the device side, Nitronex Corp. (www.nitronex.com) has answered the needs of one emerging technology with another: their model NPT35050 high-electron-mobility-transistor (HEMT) device is fabricated with gallium-nitride (GaN) process technology. Designed specifically for WiMAX power-amplifier (PA) applications from 3.3 to 3.6 GHz, the +28-VDC device generates 50-W output power at 3.5 GHz. Under more likely WiMAX conditions, with OFDM modulation, the device yields 5 W average output power at 3.5 GHz (with 12.3-dB peak to-average power) with 10 dB gain and 18-percent drain efficiency. The error-vector magnitude (EVM) at 5 W output power is 2 percent.
Another device supplier looking to nontraditional materials for its WiMAX power devices is Cree (www.cree.com) with a line of silicon-carbide (SiC) MESFET devices for WiMAX PA applications. The line includes the model CRF35030F with 4 W average output power from 3.4 to 3.8 GHz and 10-dB gain. The +48-VDC part can operate at +28 VDC. It features drain efficiency of 17 percent adjacent-channel power of ?40 dBc (according to the ETSI standard).
For enhanced mobile WiMAX, the WiMAX Forum's Mobile Task Group for IEEE 802.16e recently approved the network multiple-input, multiple-output (MIMO) software solution from smart-antenna specialist ArrayComm (www.arraycomm.com). The solution includes unique support of MIMO, adaptive antenna systems (AAS), and combined MIM/AAS modes on both client devices and base stations for the best possible use of data rates, cell range, and network capacity in mobile WiMAX systems. According to ArrayComm founder and Executive Chair Martin Cooper, "This ringing endorsement of our long-held vision of smart-antenna technology proclaims that smart antennas will drive the wireless industry's broadband revolution. Smart antennas will be as significant in the history of wireless communications as the creation of the cell phone was 30 years ago." ArrayComm software, which is implemented in wireless local-loop (WLL), PHS, WCDMA, and GSM systems, is operating in more than 260,000 commercial deployments worldwide.
With any new technology comes the potential for interference with existing and other emerging technologies. As amateur-radio (ham) operators in the United States have learned, not all attempts at providing broadband services work seamlessly with existing radio systems. In the case of radio amateurs, interference from trial and operational powering (PLC) systems, most recently from a system operating in Manassas, VA, have disrupted amateur-radio communications in wide areas around the power lines carrying high-speed data signals.
WiMAX devices will be subjected to a barrage of tests to determine how well they coexist with an increasing number of wireless devices, such as Bluetooth, WLAN, and emerging ultramodern (UWB) devices. UWB technology offers great promise for short-range, high-date-rate communications in home or small office environments. As with WiMAX, the technology is supported by a strong industry group, the UWB Forum (www.uwbforum.org), and emerging standard (IEEE 802.15), and a large number of companies with considerable marketing muscle, including Freescale Semiconductor. The company's XS110 UWB silicon-germanium (SiGe) and CMOS chip set delivers data rates in excess of 110 Mb/s for streaming video, streaming audio, and high-rate data transfer at very low power levels. The direct-sequence-UWB ( DSUWB) chip set implements the IEEE 802.15.3 media access control (MAC) protocol. The XS110 supports peer to-peer as well as ad hoc networking for truly mobile wireless connectivity. The XS110 solution includes a transceiver chip, a base band processor chip, and a MAC chip, along with a 1 1-in. flat planar antenna fabricated on FR4 printed-circuit-board (PCB) material.
To ease product developers into the adoption of UWB technology, FOCUS Enhancements (www.FOCUSinfo.com) recently introduced their Talaria UWB Evaluation System for computer, mobile communications, and consumer electronics companies designing next-generation wireless audio/video products. The evaluation kit includes a Talaria mini-PC UWB radio module that serves as a reference design for users to adapt to their own applications. The kit also contains a FOCUS Enhancements Gemini MPEG decoder card that allows testers to render a compressed media stream in either standard-definition or high-definition video format Video outputs include Firewire (IEEE 1394), component video, composite video, VGA, and DVI. Audio outputs include S/PDIF and two-channel RCA jacks.
The UWB radio is compatible with the WiMedia standard while exceeding the minimum requirements of the standard. The company's UWB radios are expected to provide data rates to 880 Mb/s at distances to 8 m and 37 Mb/s at distances to 40 m. The kit's Internet-based interface includes radio setup, monitoring, and control tools so that users can full evaluate the radio and its UWB technology.
To help UWB devices co-exist with WiMAX products, Wisair (www.wisair.com) developed an UWB "detect and avoid" technology that allows UWB devices to operate without interfering with WiMAX and 3G/4G cellular technologies. The approach requires that UWB devices employ narrowband signal detection to find other networks in the 3.1-to-4.2-GHz range, both before and during UWB system operation. Upon detection of another network, the UWB system emission level is reduced. The company offers a free white paper on the topic on their website.