Abstract
Channel equalization in filter bank based multicarrier (FBMC) modulation is addressed. We utilize an efficient oversampled filter bank concept with 2x-oversampled subcarrier signals that can be equalized independently of each other. Due to Nyquist pulse shaping, consecutive symbol waveforms overlap in time, which calls for special means for equalization. Two alternative linear low-complexity subcarrier equalizer structures are developed together with straightforward channel estimation-based methods to calculate the equalizer coefficients using pointwise equalization within each subband (in a frequency-sampled manner). A novel structure, consisting of a linear-phase FIR amplitude equalizer and an allpass filter as phase equalizer, is found to provide enhanced robustness to timing estimation errors. This allows the receiver to be operated without time synchronization before the filter bank. The coded error-rate performance of FBMC with the studied equalization scheme is compared to a cyclic prefix OFDM reference in wireless mobile channel conditions, taking into account issues like spectral regrowth with practical nonlinear transmitters and sensitivity to frequency offsets. It is further emphasized that FBMC provides flexible means for high-quality frequency selective filtering in the receiver to suppress strong interfering spectral components within or close to the used frequency band.
Highlights
Orthogonal frequency division multiplexing (OFDM) [1] has become a widely accepted technique for the realization of broadband air-interfaces in high data rate wireless access systems
Basic results are reported to illustrate how the performance depends on the number of subcarriers and the equalizer design case
The uncoded bit error-rate (BER) results were obtained for 2, 4, and 8-PAM modulations by evaluating first the theoretical subcarrierwise BERs based on the signal to interference plus noise ratio(s) (SINR)-values using the Qfunction and Gray-coding assumption, and averaging the BER over all the subchannels and 2000 channel instances
Summary
Orthogonal frequency division multiplexing (OFDM) [1] has become a widely accepted technique for the realization of broadband air-interfaces in high data rate wireless access systems. All these current multicarrier systems are based on the conventional cyclic prefix OFDM modulation scheme In such systems, very simple equalization (one complex coefficient per subcarrier) is made possible by converting the broadband frequency selective channel into a set of parallel flat-fading subchannels. One approach to deal with the fading frequency selective channel is to use waveforms that are well localized, that is, the pulse energy both in time and frequency domains is well contained to limit the effect on consecutive symbols and neighboring subchannels [5, 7, 12] In this context, a basic subcarrier equalizer structure of a single complex coefficient per subcarrier is usually considered.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
