V110 » History » Revision 4
Revision 3 (laforge, 11/20/2022 07:51 PM) → Revision 4/7 (laforge, 11/20/2022 08:00 PM)
h1. ITU-T Recommendation V.110 V.110 is an ITU standard for bit-rate adaptation of low-speed async serial signals (600, 1200, 2400, 4800, 7200, 9600, 12000, 14400, 19200, 24000, 28800 or 38400 bit/s) to 64 kbit/s ISDN B-channels. It was primarily used in the context of interworking between GSM Circuit Switched Data (CSD) and ISDN. h2. Synchronous Details Rate adaptation of synchronous serial signals of 600, 1200, 2400, 4800, 7200, 9600, 12000, 14400, 19200, 24000, 28800 or 38400 bit/s h3. Frame structure The protocol uses an 80bit (10 byte) frame. The Frame contains a frame sync pattern (similar to e.g. E1 TS0 or TRAU frames) consisting of the first byte and the first bit of every following byte. Each frame consists of * 17 bits of above-mentioned frame sync pattern plus: * 48 D-bits (D1..D48) * 7 E-bits (E1..E7) * 8 S/X-bits (S1,S3,S4,S6,S8,S9) h3. Rate Adaptation Functions h4. RA1 The rate-adaptation function RA1 converts from the V-series rates (e.g. 2400bps) to an intermediate rate of 8/16/32/64 kbit/s. h4. RA2 RA2 converts from the RA1 output rate of 8/16/32/64 kbit/s to 64 kbit/s and is actually specified in I.460 h2. Asynchronous Rate adaptation of asynchronous serial signals of 50, 75, 110, 150, 200, 300, 600, 1200, 2400, 3600, 4800, 7200, 9600, 12000, 14400, 19200, 24000, 28800 or 38400 bit/s h3. Rate Adaptation Functions h4. RA0 The RA0 function is only used with asynchronous V-series interfaces. Incoming asynchronous data is padded by the addition of stop elements to fit the nearest channel rate defined by 2 × 600 bit/s. Ther esulting synchronous bit stream is then processed with RA1 and RA2 like in the synchronous serial case.
