Optimized extended lapped transform and novel FPGA implementation

Abstract

The Modulated Filter-Banks (MFB) has been adopted in communication standards because of its improved windowing function against Fast Fourier Transform (FFT) based Orthogonal Frequency Division Multiplexing (OFDM). It has shown better resiliency to Inter-Symbol Interference (ISI), Inter-Carrier Interference (ICI), Narrow Band Interference (NBI), and Frequency Selective Fading. The recently adopted MFB in industrial standards is called Perfect Reconstructed Cosine Modulated Filter-Banks (PR-CMFB). There are three types of structure for its implementation, Extended Lapped Transform (ELT), Lattice structure, and Polyphase structure. The ELT defeats the Polyphase and Lattice structures because it is suitable for Very Large Scale Integrated-Circuit (VLSI) implementation. However, there is no difference in computational complexity between them. This paper optimizes the ELT structure to bring out its potential in the VLSI implementation. The proposed ELT reduces the required number of multipliers by half. The implementation on Field Programmable Gate Array (FPGA) is done to approve that. The simulation results show the proposed ELT has doubled throughput and one thirds of logic elements (LEs) are reserved when comparing to the conventional ELT.