Methods and systems are disclosed for frequency-domain symbol and frame synchronization for multi-carrier communication systems. It is another object of the present invention to provide an ophthalmic lens, which can form a clear and easily readable mark, without causing problems such as discoloration of the mark, caused by cleaning of the lens by rubbing, or deterioration of the mechanical strength of the lens, and to provide a marking method of the ophthalmic lens. Buffer channels are defined between memory cells and orthogonal to the columns, and buffers are selectively inserted into the routing wires in the buffer channels by placing a plurality of buffers in each buffer channel.