D2 Technologies
Reference Designs
Mobile and Personal Communications
Mobile and Personal Communications

vPort is a flexible platform that supports multiple services, such as SIP-based VoIP, VoWiFi and VoIM (PC-based IM/P2P voice such as Skype, GoogleTalk, Yahoo! and MSN). vPort leads the market in performance and efficiency, enabling networking, signaling and voice processing functions to execute as an integrated solution on a single processor.  This in turn offers substantial advantages to manufacturers in bill-of-materials (BOM) cost, power and related characteristics over traditional multi-core or multi-chip VoIP designs.  The software is highly optimized not just for quality, but for a small memory footprint, low MHz impact and low latency, and it adds real-time performance to non-real-time opertating systems.

Hardware and software design are two related, but distinctly separate engineering disciplines.  By abstracting the software layer – in other words, making it independent of the underlying hardware – D2 enables manufacturers to concentrate on product platform design and branding while leveraging the best available software, OS and IC components.  Regardless of an OEM’s design needs, D2’s highly modular architecture ensures portability to any processor, hardware or OS and delivers industry-leading features and call quality. Just as importantly, it can eliminate the expense of separate DSP components, helping drive down materials costs while actually improving power, performance and efficiency over multi-core and multi-chip VoIP products by enabling networking, signaling and voice processing to execute as an integrated solution on a single chip.  In fact, D2 has developed long-standing relationships and a solid ecosystem with the industry’s leading SOC/IC companies including Infineon, Texas Instruments, NXP and Cavium Networks.

The software package includes reference application software, voice signaling protocols (e.g. SIP, XMPP), packet processing (RTP, Jitter Buffer), voice processing (echo cancellation, voice compression, DTMF, etc.) and reference hardware-specific drivers (for audio and/or telephony devices).

vPort integrates all parts of a VoIP subsystem

  • Audio drivers for voice I/O (FXS, FXO, ADAC)
  • Voice Engine
    • Compression, echo cancellation, caller ID, etc
    • Dynamic adaptive jitter buffer
    • Packetization
  • Voice signaling
  • Application layer with calling features
  • VoIP CPE software solution for RISC SoCs, with-or-without a HW DSP
  • Excellent voice quality

Flexibility and Portability

Designed for flexibility and portability, vPort can execute on both RISC and CISC platforms under industry-standard operating systems. It is currently optimized for both ARM and MIPS processor architectures under the VxWorks, Nucleus and LINUX operating systems.  vPort’s virtual DSP architecture enables the voice DSP functions to run as “soft DSP” on a RISC processor or as DSP code on a hardware DSP core, providing further design flexibility.  The support of multiple processor architectures and Operating Systems, along with the unique virtual DSP capability, allows OEMs to choose best-of-bread components and avoid being locked into a particular hardware platform or architecture.  It also simplifies software development, support and maintenance, since all the software operates under a single environment using one set of tools.  Because of its modular architecture, vPort can be quickly modified for customer-specific applications and runtime platforms.

  • Multiple OS implementations (for latest list contact D2 sales)
    • VxWorks, Linux (2.4 & 2.6), Nucleus, Proprietary
  • Implemented in MIPS/ARM processors and TI DSPs (for latest list contact D2 sales)
    • MIPS 4kc, 4kec, 24ke, 34k, 64
    • ARM922, ARM926e, ARM11 (in process)
    • Texas Instruments C54xx/C55xx DSP processors
  • Common software, APIs, tools and development environment across all devices
  • Optimized CPU and memory utilization

Linux Enhancements: Real-time Mods and Kernel Processing

Linux has become a popular choice of OS due to its open architecture, flexibility, and lower licensing cost. However Linux faces a number of challenges when handling real time traffic such as voice. Below is a summary of typical challenges faced by real time traffic in a non-RTOS environment.

Linux Issues

  • No guaranteed interrupt latency
  • Nondeterministic task scheduling
  • Guarantee of processing time for voice tasks
  • Jitter of network packets

D2 Solution

  • Patch kernel to support
    • low interrupt latency
    • pre-emption
    • scheduling of real-time threads
  • Process voice and RTP in a real-time thread
  • Eliminates an additional user process for network access


  • Reduced process load
  • Low latency
  • Low jitter
  • Great Voice Quality

CPU Efficiency MHz/MIPS Optimized

D2’s vPort product family targets embedded devices where CPU utilization directly corresponds to higher battery consumption—one of the key differentiations of vendors particularly in the mobile handsets.

Voice Quality

vPort has been designed from the ground up to address key voice quality issues that packetize  the voice experience due to a number of factors such as delay and jitter in the network. Another key factor is the delay in processing voice due to other activities by the CPU, etc.

These issues are addressed by the careful design and implementation of Packet Loss Compensation (PLC), Comfort Noise Generation (CNG), careful design and use of Jitter Buffers, Acoustic Echo Cancellation (AEC), and OS modifications to handle Voice in real time.

Additionally, vPort is designed for integration with Wide Band Codecs such as AMR-WB, G.722.x which allows handling high quality audio not attainable in legacy networks.

Memory Footprint

Physical constraints of embedded devices typically dictate low memory availability for the system and services. Both static and dynamic memory consumptions impact the overall system, availability of resources to other services in the system.

D2’s vPort technology has been rigorously optimized for such environments and it exceeds typical embedded device requirements.