VoIP over WLAN: a use case based on ST NomadikTM chipset

This paper presents an application of DSP technology to an emerging service: Voice-over-IP in Wireless LAN networks. In this context, energy consumption is a key factor and DSP’s contribute to considerable savings compared to general purpose CPU. ST Nomadik TM application processor embeds an ARM core and DSP based accelerators for Multimedia processing. This System on Chip can be used in combination with low-power wireless peripherals to implement a VoIP application using Wireless LAN connectivity. The ARM core runs the signalling protocol and the main OS, whereas the audio DSP is responsible for voice encoding and decoding. The software interface to control Multimedia components complies with the OpenMAX Integration Layer API, recently standardized by the Khronos Group. This paper presents the overall architecture of the Nomadik System on Chip, discusses the characteristics of the VoIP-WLAN application and shows the software partitioning that has been prototyped.