WIRELESS ATM METROPOLITAN AREA NETWORK

摘要

The present invention provides an efficient point-to-multipoint microwave AT M network including a base station (BS 205) broadcasting a continuous transmission with a sector antenna (200). The system uses time division multiplex (TDM) for downstream transmission and time division multiple acces s (TDMA) for upstream transmission. The downstream transmission consists of AT M cells encapsulated in MAC protocol data units (PDUs) for forward error correction (FEC) and synchronization. Small Subscriber Terminals (STs),including Subscriber Radio Units (SRUs 202), receive the broadcast and pass it to a Subscriber Access System (SAS 204) that drops the ATM cells addressed only to them. To allow strong FEC protection and to maintain the same symbol rate as the downstream transmission without sacrificing bandwidt h, a modified trellis code modulation technique, which incorporates Reed Solomo n coding, is used during upstream transmission.