IPWireless gets its ecosystem: more on NextWave's WiMAX TV

When operators and investors ask us about NextWave, and whether or not its vision can be turned into reality, creating a new wireless powerhouse, the question is always answered with another question - can it attract tier one partners, either operators or equipment suppliers‾ Well, last week NextWave subsidiary IPWireless made a significant first step in answering that question, signing up both Huawei and Alcatel-Lucent to support its bold new MXtv WiMAX multicasting mobile TV technology (see Wireless Watch March 11 2008), and claiming that it hopes to sign further infrastructure suppliers to take the entire WiMAX mobile TV market in one fell swoop.

What the company has done is a software implementation of MBS, the 802.16e version of a multicast system, and on top of this it has dropped in the kind of mobile TV function that it already sports in its other mobile TV technology for TDD networks - TDtv, which works with TDD flavours of UMTS and potentially LTE, and is based on the 3GPP multicast standard, MBMS. TDtv has had its own breakthrough - at last month's Mobile World Congress, and after years of trials, Orange and T-Mobile agreed to move to a 2,000-user commercial trial covering a good chunk of central London, UK.

Legendary Sprint Nextel CTO, Barry West, when trialling network and mobile TV technologies for what became the Xohm WiMAX system, said in 2006: "Impressive technology, and we probably would have gone with it, if it had enough of an ecosystem around it". In choosing WiMAX networks from Nokia Siemens, Samsung and Motorola, West offered no hint about how Xohm would deliver mobile TV. Now Sprint may have the opportunity to look at the technology once again if NextWave can convince one or more of the Xohm base station suppliers to take its MXtv software and bundle it, as Huawei and Alcatel-Lucent have done, with their base stations.

The system will deliver as many as 45 mobile TV channels in Quarter VGA at 30 frames a second, each taking up around 300Kbps, in a single 10MHz WiMAX channel. It also offers channel switching times of under two seconds. Most operators won't have a full 10MHz of spectrum to throw at this, and Jon Hambidge, chief marketing officer of NextWave Network Products, told us: "If people want to offer 20 TV channels, then they will still have around 60% of their mobile broadband capacity left, which is fine for year one or year two of a new WiMAX network, and after that they can think about using more spectrum."

The system is entirely flexible on how much of the spectrum it dedicates to Mobile TV, and how much it uses for other applications. More unicast streamed video can also be sent over the mobile broadband capacity to customers on a one-to-one basis, creating the possibility of a wide range of mobile TV bouquets with MXtv, just as in TDtv. The system can dynamically allocate spectrum to TV services based on content availability, time-of-day requirements, user demand, and the availability of "˜must see' live events such as sports, concerts, interactive reality shows or emergency broadcasts.

MXtv works with wave two 802.16e base stations that implement the MBS (Mobile Broadcast Services) element of the standard. "All of the new ranges of WiMAX devices that are coming out now, and all those that Sprint has installed to date, are all wave two compliant," Hambidge explained. But NextWave has added a few extra features to the basic MBS services.


One is de signed to enhance spectral diversity benefits. WiMAX base stations tend to operate as a three-way (or more) configuration of radios, with each one using a different channel of spectrum to ensure it does not interfere with its neighbour. The MXtv idea is to create the equivalent of a single frequency network, and each of the radio segments in a base station will select an OFDM frame to broadcast the TV services. So a client device gets one TV signal from a nearby base station, and another copy of the same signal (in slightly varying frequency) from a neighbouring base station, and the NextWave mobile CPE chip combines the two signals to get a signal lift out of them, to improve reception.

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