Input buffering requirements of a systolic array for the inverse discrete wavelet transform

The Discrete Wavelet Transform (DWT) is a signal processing technique popularised by its results in data compression. Considerable work has been done in designing novel architectures to perform the DWT, including a systolic architecture designed by the authors, but little attention has been given to the inverse DWT which is needed in applications such as data compression for signal reconstruction. Despite the fact that the inverse DWT is computationally the reverse of the DWT, the hardware design for the architecture is not simply mirrored. Existing designs expect the architecture for the inverse DWT to be a simple follow-on step from the DWT design, however this is not the case. We present one such problem here, showing the FIFO buffering required on the input of the inverse architecture. We show how the size of this buffer can be calculated and compare it to a fixed data array implementation. This work is based on our systolic array design and is an integral part of the inverse DWT design we are working on for image and video compression.