Like every new wireless standard, mobile WiMAX has experienced some controversy. People in the wirelesscommunications industry have alternately doubted its viability and exaggerated its merits. With last month's launch of the XOHM mobile fourth-generation (4G) service in Baltimore, MD, however, mobile WiMAX has shown that it will likely have a spot alongside 4G telecommunication standards like Long Term Evolution or LTE (Fig. 1). The question is which application will feed the spread of WiMAX. Most people are hedging their bets on video. Both infrastructure and handsets will have to evolve to make WiMAX video delivery possible. According to most experts, however, the standard is ready to handle video.

Arthur Giftakis, Towerstream's VP of Engineering, emphasizes that WiMAX is designed with Quality of Service (QoS) parameters to support quality video. He notes, however, that one does need to define exactly what is meant by the term "quality video." As Giftakis puts it, "High-def TV has set the bar as what most people expect as quality video. If this is the case, this can be achieved using about 2.5 Mb/s of capacitywell within the ability of today's WiMAX production network."

WiMAX also has the confidence of Tyler van Houwelingen, CEO of Azulstar, Inc. He comments, "Video is no problem for WiMAX, given the 5-to-10-MHz channels being deployed by WiMAX operators such as Sprint, Clearwire, and ourselves. Great video can be done today at about 750 kb/s for a full-screen, TV-quality image using MPEG4. WiMAX handles this level for upload and download easily and reliablyeven with the lowest signal strength and modulation rates."

The solution from Livecast already enables live video streaming from mobile devices over WiMAX. According to Jennifer Blome, the company's VP of Strategic Initiatives, "Over the past year, Livecast has continually demonstrated its mobile video solution at WiMAX events with such leading WiMAX players as Intel, Alcatel- Lucent, and XOHM. A typical demo has included autos, bikes, or Segways with Livecast-ready mobile devices placed on the dash or handle bars, broadcasting high-quality real-time video of people, the streets, and interesting sites as the drivers themselves experience it at that very moment. The video-to-web transmissions look half-videogamedriving- scene and half-live-broadcast from a roving news truck." Recently, the company announced that the WiMAX Forum will use Livecast in its hands-on testing labs. The WiMAX Forum asked Livecast to forge this partnership in order to ensure that live video could be demonstrated to global operators while helping to drive customer adoption in the future.

At the XOHM launch, event attendees could ride in vehicles that went around various parts of Baltimore while streaming live video and Global Positioning Satellite (GPS) coordinates. In its service areas, the XOHM wireless services will deliver average speeds of 2 to 4 Mb/s downlink and 1 to 2 Mb/s uplink. Sprint, Intel, and their WiMAX ecosystem partners were behind this launch. The service was launched with a modem, an Express aircard, and attractive device and service offers. This month, an XOHM Universal-Serial-Bus (USB) dongle from ZTE was released.

Nokia also has begun selling the pocket-sized 810 Internet tablet WiMAX edition in the Baltimore area (Fig. 2). It has a widescreen display and QWERTY keyboard. The tablet promises to enable seamless connectivity to the Internet over WiMAX, WiFi, or 3G with a Bluetooth connection to a compatible handset. It also flaunts a built-in web camera and microphone.

For its part, Intel is already shipping a combined WiMAX/WiFi module as part of the Intel WiMAX/WiFi Link 5050 series, which is an option for Intel Centrino 2-based laptops. The WiMAX/ WiFi Link 5350 is an IEEE 802.16e and 802.11a/b/g/Draft-N wireless network adapter. It operates in the 2.5-GHz spectrum for WiMAX and 2.4- and 5.0-GHz spectra for WiFi. The adapter delivers as much as 13 Mb/s downlink and 3 Mb/s uplink performance over WiMAX and up to 450 Mb/s transmit/receive over WiFi. It is 450-Mb/s ready, as it supports three transmit and receive spatial streams.

The WiMAX/WiFi Link 5350 enables high-definition video streaming as well as applications like multi-player video gaming. Its improved reception is derived from multiple-input multiple-output (MIMO), diversity, and support for as many as three antennas. Several PC original equipment manufacturers (OEMs) have announced plans to deliver Intel Centrino 2-based notebooks with the Intel Core 2 processor with WiMAX.

Laptops also can add WiMAX networking capability with the WiMAX USB adapter from Motorola. The USBw 100 is a thumb-drivesized device. It is available in three versions to connect to WiMAX networks in each of the three bands approved for use around the world: 2.3, 2.5, and 3.5 GHz. The USBw 100 has been designed with multiple antenna technology to provide reliable, high-speed connectivity in the various and unpredictable environments where users expect service. The device, which easily plugs into the USB port, seamlessly connects the laptop computer to a WiMAX broadband network for a reliable, easy, high-speed connection for e-mail, web surfing, video and audio streaming, GPS services, Internet phone calls, and other uses.

Though WiMAX capability for notebook computers is a good beginning, some industry experts point to the lack of end-user devices as the biggest obstacle for mobile WiMAX services. As van Houweligen puts it, "There needs to be more end-user devices across different WiMAX frequencies besides just 2.3 (WIBRO) and 2.5 GHz (Clearwire/ Sprint). We are deploying at 3.65 GHz and our business model is pushed when customers can purchase and auto-provision devices on their own over our network, including video cameras. We know these devices are coming along with devices for WiMAX bands at 2.1 GHz, 1.9 GHz, 700 MHz, etc. But we want this to happen sooner. Imagine buying an FM radio or TV that can tune to only one station. This is where mobile WiMAX is today."

Of course, WiMAX consumer devices will be worthless if the infrastructure is not there to support them. Livecast's Blome comments, "Our tests have proved that we could maintain a 500k broadcast video feed, streamed live from a mobile device, driving in a car at 60 mph, for almost an hour. So, from the measure of hand-over between towers of a high-quality video stream, network coverage is uniquely consistent." Yet network coverage depends on an adequate infrastructure.

According to Tom Gratzek, Product Line Director for WiMAX Transceivers at Analog Devices, "Even though WiMAX has very good spectral/ data efficiencyessentially a figure of merit of data transmitted/hertzoperators will run out of bandwidth as data usage rises. Operators will initially deploy with macrocells, where they can claim coverage and start to market their services. As they obtain success and gather more customers, the macrocells will become overloaded. Also, as consumers get used to the services they will demand better coverage indoors, in their homes, tunnels, parking garages, etc. Operators will have to spatially re-use their spectrum in order to provide coverage to increasing numbers of customers. To do this, operators will be deploying many smaller cells."

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Gratzek continues, "Picocells are small boxes that are installed by the operator. Small deployments are happening now. To make economic sense, they must be small, consume small amounts of power, and have dramatically lower cost than the initial macrocell. Femtocells are consumer-installed devices that have even lower BOM cost and power-dissipation requirements." ADI has developed "RF to bits" capabilities that offer base-station- quality performance in an easy-to-use monolithic form. The vast majority of calibration loops are included on the device.

Tom Gruba, Motorola's Senior Director of Product Marketing, LTE and WiMAX, states, "Costeffective backhaul is one of the critical issues of high-capacity systems, such as WiMAX networks. Next-generation, wireless IP-backhaul solutions can greatly reduce overall cost of ownership versus traditional, leased-line backhaul solutions." Clearly, mobile-WiMAX operators must have network equipment that is both small and cost effective. They will then be able to roll out enough equipment to provide the necessary coveragehopefully at a price they can afford.

Last month at WiMAX World in Chicago, IL, Fujitsu Microelectronics America, Inc. unveiled a mobile-WiMAX system-on-a-chip (SoC) that was specifically designed to meet the cost requirements of a femto base-station architecture (Fig. 3). The device, which was built using 65-nm process technology, can support pico and micro base-station architectures. An on-chip processing unit delivers the power needed to handle all of the functions of a femto base station. For larger base-station applications, an additional processor can be connected by means of a PCI host interface.

The SoC incorporates all of the physical- layer (PHY) and media-access-control (MAC) features along with the analog and digital radio control. It also houses the analog circuits that are required for basestation products to pass Mobile WiMAX Wave 2 certification requirements. The power requirements are approximately 2 W, which will typically enable a full femto base station to operate on less than 10 W. The Fujitsu femto solution supports up to 10 users with seven simultaneous flowseach with enhanced support for self-organizing networks and on-chip IPSec support for non-secure, backhaul traffic applications.

A new addition also has been welcomed by Redline Communications Group's Broadband Wireless Infrastructure (BWI) products. The MAX + AN-80i operates in the 3.3-to-3.8-GHz WiMAX bands, enabling operators to cover 500 MHz of spectrum with a single softwareconfigurable- radio solution. Because it is built for high-throughput backhaul-type connections, it gives mobile operators a licensed-band alternative to pointto- point microwave technologies especially when deploying small cells in urban environments. The MAX+ incorporates contention-based protocols designed to comply with regulations for operation in the 3.65-to-3.70-GHz spectrum in the US.

Exalt Communications used WiMAX World as a stage to showcase its 5-GHz microwave backhaul radio. As an integrated native TDM and native Ethernet platform, the EX-5r GigE series delivers 440 Mb/s aggregate user throughput with guaranteed 99.999 percent availability at link ranges to 15 miles. The EX-5r promises to provide a secure, reliable microwave platform that delivers the bandwidth that service providers need for campus connectivity, camera backhaul, 3G or 4G backhaul, WiMAX backhaul, and highdefinition video broadcast.

To help the industry guarantee seamless coverage, Alcatel- Lucent offers interoperability testing (IOT) with any and all device makers under its Open Customer Premises Equipment (CPE) program. Six IEEE 802.16-2005 (Rev-e) standard devices have received the new Alcatel-Lucent Seal of Interoperability Acceptance for Commercial Services (SIACS) for completing the highest level of interoperability testing: Accton Wireless Broadband RG230 Multi-user Indoor CPE (3.5 GHz); Quanta USB Dongle (2.3, 2.5, and 3.5 GHz); Quanta PCMCIA card (2.5 and 3.5 GHz), Siemens Gigaset SX682 WiMAX (3.5 GHz), ZyXEL Max206M2 Indoor CPEs (2.5 GHz), and ZyXEL MAX216M1 Indoor CPEs (3.5 GHz). Under the Open CPE Program, Alcatel-Lucent is cooperating with device manufacturers as well as all major WiMAX Rev-e chipset providers.

These infrastructure-oriented solutions show that products are already being designed to increase mobile- WiMAX capacity. Notebook computers are on their way and smaller mobile devices will follow. As a result, a growing number of users will be enjoying video and many other applications as soon as mobile WiMAX is available in their areas. Looking at the roadmap from Sprint and Clearwire as an example, that should not be a problem. Sprint plans to roll out the XOHM network in a total of six cities including Baltimore. The other cities are Boston, Dallas-Fort Worth, Chicago, Philadelphia, and Washington. Chicago should be in good shape, as Motorola already completed the first data session on the live XOHM mobile- WiMAX network between XOHM markets and across vendor platforms. Reportedly, XOHM's goal is to provide sufficient coverage to reach as many as 140 million people by the end of 2010. By 2015, estimates say that 100 major cities could be covered.