Wireless Systems Design

Core And Software Spawn VoWLAN Devices

Traditionally, multichannel VoIP applications like residential gateways, voice-over-WLAN (VoWLAN) phones, and terminal adapters have used two processors. A host CPU runs the operating system and protocols while a dedicated VoIP DSP handles the codecs and other components. These processors would require separate development teams using different toolsets. But cost and time-to-market pressures are pushing OEMs of VoWLAN and VoIP equipment to seek single-CPU implementations.

To that end, MIPS Technologies has teamed with D2 Technologies, HelloSoft, Radvision, and Trinity Convergence. Their goal is to deliver enough performance in a 32-b synthesizable processor core to implement full VoIP functionality on a single processor. A MIPS32 24Kc core, for example, offers semiconductor OEMs more than enough performance to eliminate the DSP. The VoIP functionality can be subsumed into the host CPU including four or more voice channels. At the same time, the core provides additional headroom for new features and services.

MIPS' third-party partners support its VoIP/VoWLAN implementations with a variety of voice-related modules. The speech codecs include G.711, G.729A/B, G.723.1, and G.726. The implementations also house G.168-2000-compliant line-echo cancellers and advanced telephony/speech-processing modules. VoIP-related signaling and networking protocol stacks also play an important role. Together, these modules offer a complete VoIP/VoWLAN implementation on MIPS CPUs.

The vPort software from D2 Technologies is a complete VoIP software suite. Traditionally, voice-processing algorithms are run on the DSP that can be eliminated by the MIPS cores. Here, they are implemented in software as a "soft DSP." As a result, networking, signaling, and voice-processing functions all execute on one RISC core.

HelloSoft offers a software reference design for the MIPS cores. Radvision adds tools, platforms, and professional services for a variety of IP and 3G protocols and operating systems. Trinity Convergence's VeriCall Edge platform delivers a full VoIP software implementation that's optimized for MIPS32-based cores with an initial release under embedded Linux. Future releases will support VxWorks, Symbian OS, and Microsoft CE.NET.

TAGS: Digital ICs
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