G.994.1简介英文.pdf

? UNIVERSITY of NEW HAMPSHIRE INTEROPERABILITY LABORATORY ITU-T G.994.1 (G.hs) Handshake Procedures for Digital Subscriber Line (DSL) Transceivers A detailed look at G.hs and how it works Lincoln Lavoie InterOperability Laboratory 2003 UNIVERSITY of NEW HAMPSHIRE INTEROPERABILITY LABORATORY G.hs – Overview Presentation Overview ? Physical Layer Signaling – Modulation ? “Handshaking for G.hs” – Session Startup – Session Cleardown ? Messages – Format – Error Checking – Types – Frames – Fields – Octet Transparency – Segmentation ? Field Structure – Parameter Fields – Delimiting Bits UNIVERSITY of NEW HAMPSHIRE INTEROPERABILITY LABORATORY G.hs – Overview Some Definitions ? HSTU – Hand Shaking Transceiver Unit ? xTU-C – xDSL Transceiver Unit (Central Office) – xTU-R – See above (Remote Unit) – HSTU-C – See above. ? Transaction – A sequence of G.hs messages. ? Session – Contains startup procedure, one or more transactions, and a clear-down procedure. UNIVERSITY of NEW HAMPSHIRE INTEROPERABILITY LABORATORY G.hs – Overview Physical Layer Signaling ? 4 Carrier sets currently defined. – A43, B43, C43, A4 ? Carriers are FDM, at frequencies defined in the following tables. ? The carriers are DPSK modulated (more on this later). UNIVERSITY of NEW HAMPSHIRE INTEROPERABILITY LABORATORY G.hs – Overview Physical Layer Signaling (cont) ? A43, B43, C43 Carrier Sets – Use three carriers transmitted in each direction on three different frequencies. – All three carriers transmit the same information, and the median average of the three is the data the receiver actually parses. – Carriers are full duplex only. ? A4 Carrier Sets – Use single carrier in each direction. – Carriers are half duplex only. UNIVERSITY of NEW HAMPSHIRE INTEROPERABILITY LABORATORY G.hs – Overview Description of 4.3 kHz Family Table 1/G.994.1 – Carrier sets for the 4.3125 kHz signalling family Carrier set designation Upstream carrier sets Downstream carrier sets Transmission modeFrequency indices (N) Maximu