Most players in the cellular market will not have heard the term Integrated Mobile Broadcast, but it has just achieved an endorsement by the GSM Association, issued in a release and a white paper. The system is the next step after the largely failed MBMS and comes with a big ‘I told you so,’ from IP Wireless.
IP Wireless has been pushing the idea for a few years now that the 5MHz of unpaired TDD spectrum issued in many 3G auctions could be used to offer a high quality broadcast TV service on handsets, and free up huge amounts of 3G network capacity which is currently used by unicast TV services.
Unicast is a one to one relationship with each channel being triggered by a single viewer and no more than a dozen people able to watch TV at a time on each base station, for fear of dramatically reducing voice capacity and saturating base station backhaul. Broadcast can reach an unlimited number of handsets without a capacity penalty.
We were first told about IMB by IP Wireless at this year’s Mobile World Congress, and it is now part of the 3GPP Release 8 standard. The reason that the IP Wireless version of TDD, and in particular its TDtv service were not immediately widely taken up was because there remained the potential for interference between the FDD WCDMA signal and the TDD traffic, and it required a separate chip to receive it.
However, once delivered, IMB is thought to have enough capacity to offer 20 TV channels in a single 5 MHz TDD unpaired slice of spectrum, multiplexed down to 256K per channel, and still giving excellent quality. The signal could be delivered across an entire 3G footprint (with the addition of a number of extra transmitters) without any burden being placed on the cellular network.
The IMB standard now allows for smooth handover between IMB delivery and Unicast delivery; has the potential to be integrated onto a single WCDMA chip, and has resolved all of the interference issues, at least for spectrum in the 1900 to 1910 MHz range, with the 1910-1915 MHz spectrum needing further study and 1915-1920 MHz needing to be designated as a guard band.
The upshot of all of this is that a potential war between the way that Ericsson was implementing MBMS and how IP Wireless was advising it to be implemented, has been avoided, and both can work within the new standard. IP Wireless is hopeful that all the major base station vendors will now embrace this approach and use IMB including Ericsson, Huawei, Nokia Siemens Networks and Alcatel.
IP Wireless appears to have come out with an amount of intellectual property in the process, and although its specialist chips will only be needed until another WCDMA chip maker adds the capability to their own chips, it is hoped it will unblock mobile TV over cellular everywhere and facilitate wide scale adoption. In Europe in particular, the home of WCDMA, there is very little uptake of the rival DVB-H which requires a new network to be built and new spectrum to be acquired.
In short, IMB gives increased spectral efficiency for MBMS services but at the same time significantly reduces complexity in the user terminal, which in turn will result in lower power consumption and extended terminal battery life and it will of course cost operators less.
Initially IMB handsets may be designed with a separate chip set and RF sections dedicated to IMB. As integration advances, the RF section may be shared with W-CDMA, giving cost and space savings. As volumes rise it is thought that the IMB technology will integrate into the W-CDMA chipset.
The interference issue came because the TDD bands are adjacent to the 3G FDD uplink band which starts at 1920MHz. If interference still occurs the TDD can now back off locally and leave TV in the hands of Unicast services until it is resolved.
If this generation of cellular broadcast is now taken up there will be less of a discussion about mobile TV needing a business model, as it can of course add incremental revenue from new services, but also offer improved experience for existing unicast services, offer data transport cost reductions and open the way for new non-video broadcast services (like software upgrades).
It will also mean that cellular operators have a mobile TV option that requires little extra outlay and give them complete control instead of handing it to a broadcaster, in the way DVB-H or ISDB-T or ATSC M/H does.
IP Wireless has a ready made trial at Orange and T-Mobile in the UK (which have just merged, see separate story), but in that trial each 5 MHz segment only gave rise to 14 TV channels, but used both operator’s TDD segments and created a single 28 channel TV service. Under the new standard this could now rise to 40 separate TV channels if the two operators shared their 5 MHz of TDD spectrum.
The GSMA announced its support and is backed up with additional support from both IPWireless and Ericsson as well as operators Orange, Softbank and Telstra.
IPWireless will offer chipsets and software platforms for IMB and has been pioneering the technology since 2005 and has a lead in mobile broadcast.
Commenting on today’s news, Bill Jones, CEO of IPWireless stated: ‘Much like HSPA has catapulted the growth of mobile broadband services, IMB represents a tremendous opportunity for operators to leverage their 3G network investments to deliver innovative mobile broadcast services and efficiently handle the significant growth of video on mobile networks. As a pioneer in 3G broadcast, IPWireless looks forward to partnering with the entire industry ecosystem to accelerate IMB deployments,’