Terrestrial Trunked Radio Gateway Bypassing Transcoding
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Solution Overview
Problem
Conventional TETRA systems suffer from undesired effects on speech quality due to transcoding processes in terrestrial trunked radio gateways, which convert speech digital codes, leading to suboptimal communication performance.
Innovation Solution
A terrestrial trunked radio gateway is designed with a conference server, PCM driver, user agent server/client, and access net gateway, utilizing algebraic codebook excited linear prediction (ACELP) voice data and protocols like SIP and RTP to enhance communication between VoIP phones and TETRA networks, eliminating transcoding at the gateway and improving voice quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional TETRA systems use transcoding function to convert speech digital code in the gateway, then communication between different codes is enabled, but speech quality deteriorates due to undesired effects
Solution Approach 1:
The patent extracts the transcoding function from the TETRA gateway and relocates it to the VoIP terminal. This is achieved by implementing a VoIP terminal that includes a TETRA encoder capable of converting VoIP voice data into TETRA voice data, thereby eliminating the need for gateway-based transcoding and preserving speech quality while maintaining code compatibility.
Solution Approach 2:
The patent introduces an intermediary TETRA encoder at the VoIP terminal that acts as a bridge between VoIP and TETRA systems. This encoder converts VoIP voice data into TETRA voice data format, enabling direct compatibility without requiring gateway intervention and thus avoiding speech quality degradation.
2Adaptability or versatility
If gateway performs speech digital code conversion, then interconnection between different communication systems is achieved, but communication performance becomes suboptimal
Solution Approach 1:
The patent extracts the code conversion function from the gateway infrastructure and embeds it within the VoIP terminal device. The TETRA encoder at the terminal performs real-time conversion of voice data from VoIP format to TETRA format, enabling direct system interconnection without gateway mediation and improving communication performance.
3Ease of manufacture
If conventional gateway transcoding is used, then speech digital code conversion is achieved, but voice quality suffers from undesired effects
Solution Approach 1:
The patent removes the transcoding operation from the gateway and places it at the VoIP terminal through the TETRA encoder. This encoder converts voice data directly at the source terminal, eliminating the quality-degrading gateway transcoding process while maintaining the necessary code conversion capability.
Data Source
AI summary
A terrestrial trunked radio gateway includes a conference server configured to perform switching of audio input from a voice over internet protocol (VoIP) phone. The terrestrial trunked radio gateway further includes a pulse code modulation (PCM) driver that inserts an algebraic codebook excited linear prediction (ACELP) voice data for transmission to tetra network. A user agent server (UAS) or a user agent client (UAC) connects to the VoIP phone via a VoIP network. An access net gateway (AGW) functions as an access net common application programming interface (ACAPI) client communicating with an access net common application programming interface (ACAPI) server. The terrestrial trunked radio gateway works as a signaling gateway and allow communication between the VoIP phone and a mobile radio terminal. The VoIP phone uses a built-in algebraic codebook excited linear prediction (ACELP) codec to convert voice captured into the ACELP formulated data before transferring to tetra gateway.