On downlink channel adaptation for TDD based LMDS systems
نویسنده
چکیده
This paper considers several aspects concerning the downlink channel adaptation for TDD (Time Division Duplexing) based LMDS (Local Multipoint Distribution System) systems. First the requirements with respect to round-trip-time and complexity are considered, then a candidate scheme for the Forward Error Correction (FEC) scheme is described. The results of a simulation study of the performance of the FEC in combination with QPSK (Quaternary PhaseShift Keying) and DQPSK (Differential QPSK) modulation are given. This includes results for both coherent and non-coherent multiple-symbol differential demodulators, and the effect of recovered carrier frequency error and timing error recovery block length. Finally, joint demodulation and decoding is considered for the case of DQPSK and simulation results are given.
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