This paper describes the general conditions for perfect signal reconstruction in adaptive blocksize MDCT. MDCT, or modified Discrete Cosine Transform, is a method in which blocks are laid to overlap each other. Because of block overlapping, some consideration must be paid to reconstructing the signals perfectly in adaptive blocksize schemes. The perfect reconstruction conditions are derived by considering the reconstruction signals, on a segment by segment basis. These conditions restrict the analysis/synthesis windows in the MDCT formula. Finally, this paper evaluates two examples of window sets, including windows used in the ISO MPEG audio coding standard.

This letter proposes a fast carrier search method, the Carrier Search Step method (CSSM), to quickly detect the carrier frequency even when mobile stations have no knowledge of the carrier frequencies used [1]. CSSM consists of two operations: 1) mobile stations use the coarse-to-fine search to detect the synchronization channel (SCH), and 2) the center frequency of SCH is shifted within the channel bandwidth so that mobile stations can detect the SCH in an early step of the coarse-to-fine search. Compared with conventional methods, CSSM can reduce carrier search time by 90% when SCH bandwidth is 1.08 MHz and the channel bandwidth is 5 MHz. The reduction in carrier search time strengthens as the channel bandwidth increases.