ng, 109 "high-frequency" signal, 36 high-level data-link control (HDLC), 284-287 gating pulses, 119 frame format in, 285-287 Gaussian band-limited channel (GBLC), 272 high-power amplifiers (HPAs), 214, 228, 230 Gaussian distribution, 270, 271 of thermal noise, 48 high-usage (HU) routes, 11, 178, 180 holding calls, 68 Gaussian noise, 120, 270, 271f, 272 holding time, 56, 57 general broadcast signaling virtual channel holdover stability, 141 (GBSVC), 530 homing, 12 generic flow control (GFC) field, 517-518 hook-switch (telephone), 91-92 Generic Trap Type field, in SNMP messages, 558 hop, 323 geostationary orbit (GEO) communication hop count, 323 satellites, 217, 218 horizontal scanning generator, 408 RF bandwidth for, 37 horizontal synchronizing interval, 408 GetNextRequest verb, 557 host, 324 GetRequest verb, 557 host computer, 324 GetResponse verb, 557 host protocols, 320 gigahertz (GHz), 25 hot splice, 236 glare, 164 "hot-standby" technique, 216 go-back-n ARQ, 257-258 HTR (hard to reach) points, 552, 553 GPS (global positioning system), 140 hubs, 311 graceful close, 327 human voice communication, 90-91 graded-index fiber, 234, 235f hundred call-second (ccs), 57 grade of service, 8, 14, 57, 58, 179 HU (high-usage) routes, 176 trunk-dimensioning information for, 62, 63-65 hybrid circuits, 9f, 10 trunk utilization and, 65 hybrid fiber-coax (HFC) systems, 441-447 grading, 59 fiber-optic portion of, 441-447 grants, 354, 355 hybrid insertion loss, 77 ground, 23 hybrid modulation scheme, 274 ground return, single-wire, 23 hybrid transformer, 76-78 ground-start signaling, 164 ground system mobile (GSM), 15, 458 frame and burst structures with, 471f I-channel, 428 group delay, 47, 268 identities, 607 guardbands, 241 idle subscriber loops, 5 guided transmission, 36 IEEE 802 frame, 322f. See also Institute of Electrical and Electronic Engineers (IEEE) IEEE 802 LAN protocols, 320 half-duplex, 9, 348 IEEE 802.3 standard, 300 handover, 462 IEEE 802.11 standard, versus IEEE, 802.15, handshake procedure, 326 344-347 hardware IE