With the help of satellites, Alcatel aims to overcome a key hurdle in rolling out broadcast television services over mobile phones: the lack of available spectrum.
S-Band frequency to the rescue
The French telecommunications-equipment manufacturer proposes using the widely available S-Band frequency reserved for satellites to transmit broadcast signals both terrestrially and via satellite to mobile phones based on the DVB-H (digital video broadcasting - handheld) standard, instead of the UHF band. The UHF band is typically used for TV transmissions in Europe but has little or no capacity to spare, said Herbert Mittermayr, vice president of marketing for mobile TV systems at Alcatel, in an interview last week at the CeBit trade show in Hanover, Germany.
Broadcast mobile TV phones receive regular television broadcasts using special antennae. An alternative service, which is already available, streams video data to phones over mobile networks. The big difference is broadcast's one-to-many relationship versus a streamed transmission's one-to-one.
The Alcatel proposal calls for equipping base stations with S-Band repeaters and, in addition, using satellites capable of transmitting in the S-Band to deliver content to 3G (third-generation) phones enabled with DVB-H technology in three different ways: base-station streaming, base-station broadcasting and satellite broadcasting.
Each delivery service has its own advantages and disadvantages.
While the streamed service via the base station offers nearly unlimited channels and deep indoor coverage, it can support only a limited number of subscribers in a given area of the mobile network.
By comparison, the base-station broadcast service can support an unlimited audience with good indoor coverage but offers only 27 channels.
While the satellite-based broadcast service can support an unlimited audience, especially in rural areas, it offers poor indoor coverage and only nine channels.
"Users don't have to worry about which service to select," said Mittermayr. "An intelligent content-management system decides which of the three delivery channels is the most appropriate."
In addition to its availability, another key advantage of the S-Band is required antenna length. The frequency requires an antenna length of 6.5cm, compared to UHF's 60cm, according to Mittermayr.
The S-Band is a satellite allocation operating in the 2,170MHz-2,220MHz frequency range, which is immediately adjacent to the 3G band.
Several companies are currently developing chipsets and handsets compliant with the S-Band, as well as designing antennae and other components, according to Alcatel.
Chip maker DiBcom is designing a chipset that will be compatible with the DVB-H standard working in the S-Band, Alcatel said.
Sagem is developing DVB-H phones that support both UHF and S-Band, according to Alcatel.