Reverse spreading device, timing detecting device, channel estimating device, frequency error measurement method and automatic frequency control method

Abstract

A reverse spreading device is provided which is capable of performing timing detection and channel estimation even in a large frequency offset environment without great increases in its circuit scale and its power consumption and of expanding a range being within the AFC (Automatic Frequency Control) for the frequency offset. A multiplication is made by multipliers between complex base band signals and spread codes and then resulting n-pieces of multiplied values are integrated by m-pieces of adders for every k-pieces of multiplied values to produce m-pieces of complex intermediate signals before obtaining complex symbols. A probability of correct synchronization is increased by providing a frequency offset to m-pieces of complex intermediate signals using phase rotators to compensate for rotation within one symbol period and to obtain a great spreading gain. A range being within the AFC for the frequency offset is expanded since a phase error is corrected before a production of the complex symbol signals.