標準號：IEC/TS 61334-5-3-2001
中文標準名稱：使用分配線載波系統(tǒng)的分配自動化.第5-3部分:低層文件.擴展譜帶適配的寬帶截面
英文標準名稱：Distribution automation using distribution line carrier systems - Part 5-3: Lower-layer profiles; Spread spectrum adaptive wideband (SS-AW) profile
標準類型：M11
發(fā)布日期：1999/12/31 12:00:00
實施日期：1999/12/31 12:00:00
中國標準分類號：M11
國際標準分類號：33.040.60
適用范圍：This specification describes the requirements of the spread spectrum adaptive wideband (SS-AW) approach which incorporates the services provided by the physical layer entity and the MAC sublayer. The transmission medium is assumed to be the distribution network on both the MV or LV level. The MAC sublayer described in this specification interfaces with the logical link control (LLC) layer described in IEC 61334-4-32. The noise and signal attenuation characteristics of the MV and LV networks require a hierarchical approach, where methods for modulation/demodulation, synchronization, equaliza-tion, error control coding, and media access control are designed specifically for this hostile communications environment. This approach includes a low-level link protocol within the MAC sublayer that incorporates some functions generally associated with a data link control procedure. This specification describes such a hierarchical approach based on a spread spectrum physical layer with fast synchronization enabling short-duration transmissions and adaptive equalization. This coupled with a low-level link protocol, the effective utilization of error correction and detection, and robust medium access management provides a robust, reliable platform for the LLC sublayer. The adaptive component of this approach refers to the equalization method used to compensate for the time-varying nature of the communication channel impairments. The receiver must select appropriate equalization values to adapt to the changing channel characteristics, which can be node-specific, on a frame basis to achieve optimal performance. The equalization parameters are adjusted based on various quality metrics available from the received frame, for example, the Hamming distance of the synchronization preamble, the error-free status of the frame header and data block, if present, or the failure to receive an expected response. The equalization methods are well-known and the precise method is determined by the particular implementation of this specification. This allows cost/performance trade-offs and future improvements to occur without losing compatibility.