Digital radio based on the Digital Audio Broadcasting standard has been widely available across the UK since 2001, but it hasn't had enormous success. DAB radios consume ten times as much power as an FM radio, restricting the possibilities of portable devices. As well, the audio quality has generally been lower than FM, due to the bitrate chosen by the broadcasters.
Australia has settled on the new DAB+ standard, which uses the highly efficient AAC+ codec (DAB used MPEG-1 Audio Layer II). This provides excellent audio quality at low bitrates. The DAB+ chips currently being produced have one third the power consumption of DAB, so it's still hungrier than analog, but much closer.
On the electromagnetic spectrum, DAB+ sits a bit above the FM frequencies, just below the television (digital and analog) area.
I'm hoping that the closeness of the DAB+ to the FM band will mean that there will be few technical difficulties in introducing DAB+ to mobile phones. My hopes are high, especially as a demo has already been shown.
It has taken until late 2008 for a mobile phone incorporating an AM radio to appear in Australia, the snazzy Sony Ericsson R306. Unfortunately, to listen to the radio an ugly gimcrack antenna needs to be attached (I think it's the ferrite core AM antenna, which either won't fit or is adversely affected by the phone's own signalling) ruining the usability of the device. A DAB+ mobile phone should alleviate this problem.
To confuse matters, another digital radio system is also on the horizon. Digital Radio Mondiale is in the same family as DAB, but runs in the AM frequency range. This makes it work much better over long distances. In Australia, suitable frequencies for DRM have been reserved, but no announcements have been made about when it might be used. I imagine that we will eventually use both systems, DAB+ for mostly urban areas, and DRM for the Nullarbor Plain.
Current radio stations have an automatic licence to broadcast in DAB+. As well as their current AM/FM offerings they may also choose to transmit additional stations. However, if they don't use their DAB+ slot then it will be taken from them. This should encourage most current stations to offer digital simulcasts soon after the May launch. There don't seem to be any DAB+ radios for sale in Australia yet, but it won't be long. These are exciting times for everyone.