| 摘要 |
Apparatus is provided for communicating data packets in variable length bursts over a physical layer in a multilayer data communication scheme. Each burst contains information data (40, 50, 60, 64, 74, 78, 82) and overhead (30, 32, 34, 36, 38, 42, 44, 62, 66, 76, 80, 84). The overhead includes forward error control (FEC) data (42, 62, 66, 76, 80, 84). Different burst modes (Figs. 2, 3, 4, 5) are provided to enable a trade-off to be made between bandwidth efficiency and data transmission robustness. The burst modes provide different combinations of modulation (such as QPSK and 16-QAM), symbol rates, FEC coding levels and frame and preamble structure. The apparatus is particularly suitable for use in upstream communications over hybrid fiber coax cable television plants. |
