A radio communication system in which information of a unit length is constituted with a plurality of frames as a set and the information is transmittedreceived between a base station and a mobile station. The call is then routed via the base station, at least one routing unit, a routing link, and a switching unit. We form a first dielectric layer over the gate dielectric layer and the substrate. Ranking can be based on trainable algorithms that utilize feature vectors for candidate answer strings. Thereby, it is possible to obtain a semiconductor memory device capable of reducing generation of multi-bit errors.