The GSM Association (GSMA) has recently announced that it is endorsing a new 3GPP (3rd Generation Partnership Project) standard called Integrated Mobile Broadcast (IMB), a technology that enables spectrally-efficient delivery of broadcast services, based on techniques that are greatly aligned with existing FDD (Frequency Division Duplexing) WCDMA (Wireless Code Division Multiple Access) but also allowing deployment in TDD (Time Division Duplexing) spectrum. According to the GSMA, the technology will enable its members to accelerate the adoption of mobile data and broadcast services worldwide.

Operators can use IMB within segments of spectrum already allocated with many 3G licenses, but which have remained unused due to a lack of appropriate technology. Since IMB meets the necessary regulatory and spectral requirements to be deployed in this spectrum, operators can now use this valuable but previously untapped asset. IMB also reuses many aspects of existing, deployed technologies such as Universal Mobile Telecommunications Service (UMTS) and Multimedia Broadcast Multicast Service (MBMS), meaning a short development cycle for inclusion on products resulting in a faster time to market for mobile broadcast services such as mobile TV.  The goal of IMB is to make use of what has already been done and make it easy to integrate with already deployed networks, but at the same time take advantage of a number of new features.

One of the major advantages is that operators can start taking advantage of previously unused TDD (Time-Division Duplex) spectrum, which most operators in Europe received when they were awarded 3G licenses, says Dan Warren, director of technology, GSMA. Spectrum is also available across Asia and most parts of Latin America and North America, he said.

Whereas before TDD and FDD (Frequency-Division Duplex), which is used by WCDMA (Wideband Code Division Multiple Access) 3G networks, were viewed as separate standards, IMB can be used to merge the two. The data is sent using TDD, authentication and digital rights management, and any interaction with the user is sent over the existing 3G network.

“IMB has been created through collaborative mobile industry effort and offers mobile operators an opportunity to launch new services to their customers,” notes Alex Sinclair, chief technology officer at the GSMA. “The GSMA is delighted to be endorsing this technology and we look forward to seeing the advanced services the mobile operator community will deploy using this flexible new mobile broadcast standard.”

There are 3 main trends that are currently driving the need for IMB:

  • The rapid growth in mobile data volumes – largely being driven by video and multimedia traffic.
  • The constrained growth in 3G unicast  network capacity
  • The high proportion of data traffic files that are accessed on a limited number of websites. For example, research shows that mobileYouTube viewing rose 1700% in the first half of 2009, however only 3% of YouTube videos are viewed over 25,000 times and generate the majority of YouTube traffic.

Key benefits of IMB include:

  • avoidance of congestion on existing unicast 3G data networks
  • enabling of innovative, high-bandwidth data services
  • improved user experience of existing broadcast applications and services
  • lower cost of delivery of content to mobile devices

The GSMA got involved in IMB at the behest of some of its member operators, according to Warren. The standards work had reached a blocking point between Ericsson and IPWireless and the GSMA helped solved those issues, which were about frame formats and "very technical and quite trivial", Warren said.

The name of the technology was also changed from Downlink-Optimized Broadcast (DOB) to IMB. "There was quite a lot of stigma attached to the previous name as a result of this quite acrimonious, at times, standards work," explains Warren.

For users, the adoption of IMB will mean better mobile TV picture quality, since the technology makes it possible to use more bandwidth per channel. It also lets operators offer more channels and sends them to more users.

However, mobile TV isn't the only application that IMB can be used for. Any application that needs to send lots of the same data to a large number of users is a good fit for IMB. Other uses include digital radio, application and content downloads, and the distribution of common content on internet services such as YouTube as well as Spotify, which is a streaming music service.

In order for IMB to work, a phone needs to be equipped with an IMB chipset. Operators backing the technology include SingTel, Orange, Softbank, Telstra, T-Mobile and Vodafone, according to the GSMA.

IMB will now be one of 5 technologies endorsed and promoted by the GSMA, speaking for the potential of the technology to become the preferred mobile broadcast standard for the industry. Other technologies endorsed by the GSMA include HSPA & WCDMA.

GSMA's endorsement of IMB comes with a white paper that provides a guide to IMB technology for mobile network operators on how the technology can be used.  The GSMA IMB Service Scenarios and System Requirements white paper covers the technology in greater detail, including spectral requirements for deployment of the service, capabilities that are required to be supported in the operator’s network and upon devices, and a range of examples of services that could be implemented using IMB as the underlying delivery technology. In combination with 3GPP specifications, the white paper will allow infrastructure and handset manufacturers to develop common implementations of IMB, which in turn will promote mass adoption through the generation of economies of scale and an IMB ecosystem.

The white paper is available to download via the following link:

By Shanti Anne Morais