Skip to main content

Table 2 FWT versus FFT sensing complexity comparison

From: Optimized spectrum sensing algorithms for cognitive LTE femtocells

FWT

FFT

A single FWT operation per LTE OFDM symbol (5 slots × 7 FWT operations)

The five LTE slots are divided into FFT blocks according to the FFT size, the average FFT of these blocks is the output of the FFT sensing module

Complexity = 2 × (Number of samples per LTE OFDM Symbol) × 7 × 5 × M × L

Complexity = (Number of FFT blocks per 5 LTE slots) × FFT_Size × log2(FFT_Size)

Daubechies (dbN) wavelets are used where N is the filter order

256 and 512 point FFT modules are used

1598520 computations for db2 FWT

3197040 computations for db4 FWT

1599488 computations for 256-point FFT

1797120 computations for 512-point FFT