COMMUNICASIA, SINGAPORE--Voice may be the killer application for broadband now, but service providers should not rush into offering voice-over-WiMax services, said the president of Soma Networks.
Greg Caltabiano, who is also the chief operating officer at the wireless broadband equipment company, explained that the technical characteristics of voice-over-IP (voice-over-IP) means that there will always be constraints when it comes to its delivery over wireless networks.
"Voice-over-IP was developed to work over a network where bandwidth is unconstrained (as with wireline networks)... But bandwidth in wireless is always constrained," he said, speaking to attendees at a broadband conference held at CommunicAsia Thursday.
Moreover, technical issues like jitter and delay, which users are sensitive to, remain unresolved in VoIP-over-BWA (broadband wireless access) applications, Caltabiano added. "The human ear is very sensitive. [Even in voice transmitted] over satellite, if you have a quarter-second delay, you would notice it."
Caltabiano also took issue with the way the media have presented VoIP-over-wireless issues. "In the press, they make it as if all you need to do is have quality of service (QoS) controls. QoS handles congestions [issues] only, not changing of channels or latency or jitter," he said.
Wireless broadband equipment use frequency channels to transmit signals, and channels can be changed to prevent interference.
Caltabiano pointed out that besides capacity and quality problems, voice over wireless also faces interoperability challenges. To overcome this, voice over wireless will need a set of standards similar to those that have been set for VoIP over wireline networks, such as Session Initiation Protocol (SIP) and those ratified by the IETF (Internet Engineering Task Force), he said.
The goal of access networks is to somehow make the voice application "not care that it's working over wireless", he said, adding that this can be done by building specific middleware into the wireless broadband equipment.
Service providers, which are leading the adoption of WiMax and thinking of offering voice over wireless, should therefore focus on the business case, and not just the technology. "Offer services on a limited coverage [first]… Go through a progression," he advised.
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