OXFORD, United Kingdom-Cellular penetration rates now exceed 50 percent in Finland. But real penetration rates are much higher if you ignore the very old and the very young. Pretty well every Finn who can walk and talk now has a mobile phone.
Amongst Finnish youth, the penetration must be close to 100 percent. You are regarded as a social outcast if you don’t have a mobile. But young Finns don’t just use their mobile phones for talking. For certain age groups, data traffic now exceeds voice traffic. Teenage girls in particular have become avid users of GSM’s short message service (SMS). An SMS sub-culture has emerged in which groups of teenagers chatter silently but effectively through their mobile handsets. Twenty messages per person per session is not uncommon. It’s the mobile equivalent of Internet chat.
Such groups soon could have a new dimension added to their communicating lifestyle. Finnish vendor Nokia Oy claims to be the first manufacturer to introduce high speed circuit switched data (HSCSD) to the GSM (Global System for Mobile communications) market. And one of the first implementors will be Finnish operator Sonera Ltd. MobileOne (Asia) Pte. Ltd. of Singapore also is introducing a Nokia HSCSD system, and the vendor claims 15 customer contracts to date.
HSCSD is a software solution for GSM that increases data rates from 9.6 kilobits per second to 14.4 kbps. It also allows multiple time slots to be used for a data connection, providing capabilities of 28.8, 43.2 and 57.6 kbps. In essence, HSCSD upgrades GSM data capability to the equivalent of a landline modem.
Use of multiple time slots in this way can reduce voice capacity in the network. Not a major problem, according to Nokia, which argues that patterns of data traffic differ substantially from voice. The company maintains implementing HSCSD as an add-on feature to a GSM network represents significant additional revenue-generating capability.
HSCSD is a circuit-switched system suitable for file transfers and applications such as video that require constant high bit rates and constant transmission delays. But are the data rates high enough for real-time video?
“HSCSD makes GSM technically video-capable,” said Hannu Nieminen, head of the Visual Communications Laboratory at the Nokia Research Centre in Tampere, Finland. A recent demonstration on a test network in Helsinki proved his point. Low-motion video indeed can be transmitted over GSM with acceptable quality. Teenage girls in Finland are no doubt already exchanging messages about their future use of the system.
They should not get overly ambitious. Nieminen points out that 28.8 kbps is adequate for video-phone applications, but warns the picture quality depends on the amount of movement. Acceptable quality is achievable for low motion scenarios such as talking heads or picture postcard scenes. Picture postcards could become a common application with the introduction of digital cameras built into mobile handsets, believes J.T. Bergqvist, senior vice president, Radio Access Systems at Nokia Telecommunications, observing “the sending price of a digital image is less than that of a postcard.”
But some suggested applications, such as re-broadcasting of television programs onto mobile devices, still seem ambitious, even with the latest digital-compression techniques.
The broadcast world provides the benchmark. Broadcast-quality video uses a basic data rate of 216 Megabits per second, said Philip Laven, director of the Technical Department at the European Broadcasting Union. With MPEG-2 compression techniques, 98 percent of the data can be discarded without significant loss of picture quality, allowing normal news coverage to be just acceptable at 2 Mbps.
It is the tiny picture size available on a mobile handset that could allow news coverage to be transmitted at 28.8 kbps. But that is news of the talking head variety. Fast-moving scenes such as sports require at least three times the data rate acceptable for talking heads. “TV news usually contains sports coverage,” warns Laven.
