Broadcom cleans up noisy mobiles

3GSM: M-Stream could put an end to crackly mobile phone calls and dropped connections in busy locations

American chipmaker Broadcom announced a new technology to increase the range and reliability of mobile phone communications on Tuesday, at the 3GSM World Congress in Barcelona.

Called M-Stream, the proprietary technique effectively halves the susceptibility of a mobile phone call to noise when the signal is poor or interference is present. This makes voice calls more reliable and enhances the reliability of data connections while reducing the rate of dropped calls, Broadcom claimed.

M-Stream also improves voice quality on lower bit rates, which many operators are adopting to get higher numbers of users per cell. "With this, the quality of the transmission at half rate is almost as good as full rate", said a Broadcom spokesman at 3GSM.

The company says that many handset manufacturers and operators are looking at the new technology, which is being added to all Broadcom's mobile chipsets from GSM to 3G WCDMA services.

ZDNet UK was given a demonstration of the technology under lab conditions, where it turned a borderline call with barely acceptable performance into one that sounded practically perfect. Broadcom claims that this will allow network operators to support twice as many users per cell as previously with no further investment.

M-Stream works purely in the handset as part of its digital signal processing of the baseband data stream, and doesn't need any changes to the mobile operator's network infrastructure. It is combined with a further technique called single antenna interference cancellation (SAIC), which also helps safeguard the control channel that runs alongside the voice to maintain the call.

Although Broadcom isn't revealing details of the technology, the company did say that it involves "a wrapper around the Viterbi decoder that gives two to three decibels improvement". In other words, it enhances one of the core techniques used to extract data from the radio signal. Viterbi decoding is a key aspect of most modern wireless communication; if M-Stream proves itself in practice it could find much wider application in networks and radio communication of all kinds.