Another fix for the mobile TV capacity problem

Earlier this week, IPWireless, which makes chips and wireless equipment for the cellular industry, announced the technology, called TDtv, claiming it provides enough capacity over existing 3G spectrum so that mobile carriers won't have to rely on separate overlay networks to carry live TV programming, which use up relatively large amounts of bandwidth.

Though mobile operators around the world have spent billions of dollars over the last few years building new 3G wireless networks in order to deliver new services, experts say their networks are not equipped to handle high volumes of live TV traffic.

The reason is simple: 3G wireless networks are designed to be "unicast," which means signals are transmitted between a single sender and a single receiver. This means that the same piece of content has to be retransmitted over the network every time a different user wants to view it, eating up valuable bandwidth along the way.

Tech giants Qualcomm, through its MediaFlo subsidiary, and Crown Castle International, through its Modeo division, are building broadcast overlay networks to the 3G network. They plan to sell wholesale capacity on their network to cell phone carriers who want to carry live TV programming.

IPWireless has taken a different approach to solving the mobile TV problem. Instead of building a separate network, the company has adapted the standardized Universal Mobile Telecommunications System (UMTS) TD-CDMA technology, which provides high-speed wireless access for laptops and other Internet devices, so it transmits wireless signals in multicast instead of unicast. To take advantage of the new TDtv technology, operators will have to upgrade cell towers with additional radios.

"The big difference between what we are doing and what MediaFlo and Modeo plan to do is that with our technology mobile operators still own and control the network," said Chris Gilbert, CEO of IPWireless. "As long as it's economically efficient, mobile operators would rather own and run the network themselves rather than share revenues with another operator."

But others in the wireless industry disagree. Bob Shallow, director of multimedia experiences for Nokia North America, said it depends on who you talk to within the mobile operator.

"The network guys definitely don't want to give up control of the network," he said. "But the investor relations guys don't want to have to go back to investors and say, 'Hey, we need more money to upgrade this network we just spent billions of dollars building.'"

In terms of quality, IPWireless claims that video using the TDtv technology will be comparable to what MediaFlo and Modeo promise. It should be able to deliver up to 50 channels of TV for standard mobile phones, or about 15 high-quality channels over 5MHz of unpaired 3G spectrum, the company said.

So far only one mobile operator--IPMobile in Japan--has announced plans to test IPWireless' TDtv technology. But it's very likely that Sprint Nextel will also test the technology. Sprint Nextel announced this week that it has added an additional $10 million in funding to the $4 million the company previously invested in IPWireless back in July. Sprint Nextel is currently testing IPWireless' UMTS TD-CDMA technology in the Washington, D.C., area for mobile broadband access.

What's more, Sprint Nextel has a large portion of 2.5GHz spectrum, which Gilbert claims is ideal for TDtv.

MediaFlo has already signed up Verizon as a customer for its service when it launches later this year. Modeo has yet to announce customers, but several handset makers, such as Nokia, are already building phones that will support the service.