 292-294 line code, 119-120 local area wire-pair trunk (junction) design, line concentrators, 74 102-103 INDEX local bridges, 309-310 lost calls, 56, 58 local exchange carrier (LEC), 2 handling, 60 local exchanges, concentration/expansion of, 68, 71 lost calls cleared (LCC) method, 60 local multipoint distribution system (LMDS), RF lost calls delayed (LCD) method, 60 bandwidth for, 37 lost calls held (LCH) method, 60 local networks, 169-173. See also local area lost packet rate, 394 networks (LANs) loudness rating (LR), 14, 42-43 design of, 170-173 attenuation and, 94 evolution of, 169-170 determination of, 44 local switches, essential functions of, 68-70, 71 low earth orbit (LEO) satellites, 197, 217, 219 local telephone switch, 67 advantages and disadvantages of, 484-485 local trunk circuits, VF repeaters on, 104 low-noise amplifiers (LNAs), 214, 223, 230 locating, 462 low-pass filter, 80 locked mode, 495 low trunk insertion losses, 102 logarithmic curve laws, 113 logarithms, 593, 612-613 logical link control (LLC), 295-297, 300. See also M12 multiplexer, 122, 123 LLC entries MAC frame, 301-304. See also medium access control field, 298, 299f control (MAC) PDU structure, 298 token ring, 307-308 user services of, 297-298 transmission requirements, 303-304 long-distance broadband systems, 85 MAC header, 351, 352f long-distance communication, telegraph as a form machines, in transmission systems, 3 of, 21, 22f MAC layer, IEEE 802.11 standard, 342 long-distance connections, 75-76 MAC PDUs, 349, 351f long-distance network design, 173-180. See also national networks MAC protocol engine, 349 MAC requirements, IEEE, 802.16, 348-359 exchange location, 175 MAC SDUs, 351 hierarchy in, 175-176 link limitation, 174-175 MAC sublayer, DOCSIS, 453 numbering plan areas, 175 magnetic fields, 585-586 procedures for, 176-180 magnetism, 585-586 sample, 179f main distribution frame (MDF), 169 long-distance PCM transmission, 126-128 main frame facility, 102 long-distance telephony management, SCCP, 380 echo and singing in, 187-191 ma