LONDON — Four of the U.K's mobile network operators have started technical trials of TDtv, the mobile TV variant developed by IPWireless that is based on existing 3GPP specifications and allows operators to use their idle TDD spectrum.

IPWireless, which has already sold its TD-CDMA based technology to several operators for broadband wireless, announced the TDtv technology earlier this year, when it said it received another $10 million trance of investment from U.S. carrier Sprint Nextel that brought total investment to $200 million, mostly from venture capital groups.

3UK, Orange, Telefonica, and Vodafone will test the system in the Bristol area using 12 of Orange's cell sites, delivering TD-CDMA-3GPP Multimedia Broadcast and Multicast Services (MBMS) to people issued with special compact flash cards that plug into a Dell PDA.

The trial is expected to provide valuable insights for mobile operators into the potential of using their existing spectrum and infrastructure to deliver mobile television and other multimedia services.

"We have chosen to do a multi-operator trial to prove interoperability with providers already offering W-CDMA 3G networks, and show that, from a technical perspective, the system can be managed and can share antennas so as to receive calls while watching TV on the mobile," Bill Jones, COO of IPWireless (Chippenham, England) told EE Times Europe .

The flash card uses silicon that IPWireless already uses in its TD—CDMA equipment, but, as Jones concedes, only uses a segment of that device for these trials. The company is designing devices specifically for implementing TDtv in W-CDMA handsets, and is talking with the majority of 3G handset makers.

The cell sites have been enabled with TDtv base stations provided by IPWireless, and are said to cover about 60 percent of the Bristol area. The area includes a major motorway, the M4, so that reception of mobile TV at speeds over 110 km/h can be tested, said Jones.

MobiTV, Inc., the international mobile and broadband television services company, is providing the client application, as well as facilitate the mobile content and operational components of the trial.

Operators in the U.K. are already testing the other versions of mobile TV. For instance Telefonica's O2 unit is trialing DVB-H in the Oxford area in conjunction with Nokia, while BT and Virgin Mobile have trials of the DAB-IP based Digital Multimedia Broadcast (DMB) technology. Satellite network operator BSkyB is trialing the Qualcomm developed and backed MediaFLO system.

Professor Michael Walker, Director of Research and Development at Vodafone said: "Trials are an extremely important part of our strategic product development. In the case of mobile TV, there are a number of technologies emerging that must be fully explored so that we have a comprehensive understanding of how the technologies work and the experience they will offer. Currently the most interesting technologies are the variants of MBMS and DVB-H and this trial forms part of the MBMS assessments we are undertaking."

IPWireless says TDtv offers operators already offering W-CDMA services significant strategic, performance, and economic advantages over the competing mobile TV solutions since it allows such providers to utilize existing spectrum and infrastructure. The company maintains the deployment of TDtv would require a low capital expenditure by the operator as a single base station controller is required for 100 Node B's, while utilizing the operator's network eliminates the need to split revenues with broadcasters, who generally own the required spectrum.

Vivek Badrinath, Executive Vice President, Product Technology and Innovation, Orange. "We believe that it is important that leading service and content providers work together to examine options for future mobile TV platforms."