Radio over Internet Protocol (RoIP) Presenter : Farhad Fathi May 2012
What is VoIP? [1] Voice over Internet Protocol is a method for taking analog audio signals, like the kind you hear when you talk on the phone, and turning them into digital data that can be transmitted over the Internet (or Local Area Network). The analog audio is encoded with a standard audio codec, such as G.711, G.723, GIPS or GSM. The digitally encoded audio samples are then packaged in UDP (User Datagram Protocol), RTP (Real- Time Transport Protocol) or a similar transport layer protocol for transport over an IP network. At the far end of the transport, the digital audio is decoded back to an analog audio signal.
What is RoIP? [1] Radio (Control) over Internet Protocol uses standard VoIP techniques to transfer the analog audio, used by Land Mobile Radio systems, digitally over the Internet (or LAN). In addition to voice, RoIP also transfers signals that are specific to LMR applications, such as PTT and COR control lines. Upgradeable to allow many more features of radio control over the Internet. Some possible features could be: Reprogramming of the radio features (frequency, tone, etc.) Alarm monitoring (high VSWR, AC power loss, etc) Control functions (switching to a secondary LMR system,turning on generators, etc.)
Principle functions of a RoIP channel [2]
RoIP Implementation Principle [1]
What is a Speech/Audio Codec? All codecs are devices or computer programs capable of coding or decoding a digital data stream or signal [3] Audio Codec In software, an "audio codec" is a computer program implementing an algorithm that compresses and decompresses digital audio data according to a given audio file format or streaming media audio format. In hardware, "audio codec" refers to a single device that encodes analog audio as digital signals and decodes digital back into analog. In other words, it contains both an Analog-todigital converter (ADC) and Digital-to-analog converter (DAC) running off the same clock.[3]
What is a Speech/Audio Codec? Speech Codec Speech coding is the application of data compression of digital audio signals containing speech. Speech coding uses speech-specific parameter estimation using audio signal processing techniques to model the speech signal, combined with generic data compression algorithms to represent the resulting modeled parameters in a compact bitstream[4]. Very low Bit rate Speech coder for Military Application Code Excited Linear Prediction (CELP) coding (for example used in GSM) Wide-band speech coding AMR-WB for WCDMA networks VMR-WB for CDMA2000 networks G.722, G.722.1, Speex and others for VoIP and videoconferencing Narrow-band speech coding FNBDT for military applications SMV for CDMA networks Full Rate, Half Rate, EFR, AMR for GSM networks G.723.1, G.726, G.728, G.729, ilbc and others for VoIP or videoconferencing
Introduction to G.729 Coder G.729 is an audio data compression algorithm for voice that compresses digital voice in packets of 10 milliseconds duration. It is officially described as Coding of speech using conjugate-structure algebraic code-excited linear prediction (CS-ACELP) [5] G.729 Annexes[5]
Introduction Coders G.729 SSACC Reference Transport Voice Traffic on WLAN Channel Occupancy Time for Various Codec Settings [6] G.729.1 As a new scalable speech and audio codec and can cover wideband (50-7000Hz) to support high quality over IP [6]
Introduction Coders G.729 SSACC Reference A Scalable Speech Coder Control Algorithm [6] Structure of the Scalable Speech and Audio Codec Control (SSACC) [6]
Introduction Coders G.729 SSACC Reference A Scalable Speech Coder Control Algorithm [6] Procedure of the Scalable Speech and Audio Codec Control (SSACC)[6]
Introduction Coders G.729 SSACC Reference Simulation of Proposed SSACC [6] Simulator Type: http://www.opnet.com Simulation Results OPNET Simulator (Software available at Media Access Delay of an AP Voice packet End-to-End delay
Introduction Coders G.729 SSACC Reference [1]Douglas Bigrigg, Radio Over internenet Protocol, Daniels Eelectronic LTD, http://www.danelec.com/pdfs/roip%20presentation.pdf [2]TestAdvance pty/ltd, Implementing a Radio-over-IP Infrastructure [3] Wikipedia, the free encyclopedia, http://en.wikipedia.org/wiki/audio_codec [4] Wikipedia, the free encyclopedia, http://en.wikipedia.org/wiki/speech_codec [5] Wikipedia, the free encyclopedia, http://en.wikipedia.org/wiki/g.729 [6] Ki-Jong Koo; Do-young Kim, A scalable speech/audio coder control algorithm to improve the QoS of VoIP calls over WLANs 14th European Wireless Conference, 2008.