| 摘要 |
PROBLEM TO BE SOLVED: To enhance reception performance by enhancing the equalization performance of a received signal waveform in a multilevel QAM modulation system, without requiring a specific reference signal sequence. SOLUTION: The transversal filter type adaptive equalizers 106-1, 106-2 provided to a receiver receiving a modulation signal, adopting the multilevel QAM modulation system use the CMA(constant modulus algorithm) to calculate a tap coefficient. An evaluation function used in this case is switched alternately to J12 or Jt for each iteration. An error ε, calculated by the evaluation function, is compared with a specified value δ and when the error ε is smaller than the value δ, and the least mean-square error algorithm is selected for the calculation algorithm of the tap coefficient from the CMA. In the least mean-square error algorithm, a bit sequence corresponding to a convergence point closest to the signal point of an equalization signal outputted from the adaptive equalizers 106-1, 106-2 is used for the reference signal sequence. |
