Multicarrier waveforms with I/Q staggering: uniform and nonuniform FBMC formats

Abstract

Starting from the well-known uniform filter bank multicarrier (FBMC) format with Nyquist spectral shaping of frequency-limited orthogonal (FLO) subchannels and its dual time-frequency, time-limited orthogonal (TLO) form, we introduce an orthogonal frequency division multiplex of nonuniformly spaced subchannels with unequal width. The orthogonality conditions for nonuniform FBMC (Nu-FBMC) were evaluated through simulations using the 'extended orthogonal frequency division multiplexing (OFDM)' framework, as well as through analytical derivation in a rather pragmatic manner. The referent filter bank impulse responses were defined in frequency domain by straightforward aggregations of the pertaining uniform filter bank subchannels spectral shapes for FLO and by transforming the frequency domain of appropriately aggregated time-limited referent impulse responses of uniform TLO configuration. Nonsymmetrical spectral shaping of subchannels in the FLO case format has also been proposed. The spectral efficiency has been evaluated in the presence of nonlinear distortions caused by high power amplifier (HPA), and results have been given in accordance with power spectral density (PSD) constraints defined by IEEE 802.11a standard.

New multiple‐input multiple‐output‐based filter bank multicarrier structure for cognitive radio networks

“…It also ensures orthogonality in real domain to maximise spectral efficiency [6]. OQAM‐FBMC has better spectral shaping of the subcarriers than that of the CP‐OFDM systems [6, 7]. This can be accomplished by using an advanced basic pulse called PF that helps in the equalisation process in the absence of the CP.…”

“…FBMC is by far less sensitive to ICI and shows higher robustness against residual frequency offsets. It is, therefore, able to achieve higher spectral efficiency than CP‐OFDM [7]. FBMC also does not require the addition of CP and as a result, it increases the overall data rate and the bandwidth utilisation.…”

Comparing the performance of OFDM and FBMC multicarrier systems in doubly-dispersive wireless channels

“…For a special choice of the prototype filter it is much similar to the first analog multicarrier system introduced by Chang [8], whose relation with OFDM/OQAM (for a proper adjustment of the intercarrier spacing) is reported in [9]. An unified view of the two systems by considering the "even-spaced" and "odd-spaced" cases (even or odd multiples of half the subcarrier spacing) is reported in [10].) The scheme is based on pulse amplitude modulation (PAM) combined with a sine prototype filter with overlapping factor K=2 and it achieves full orthogonality, like OFDM.…”

Software Implementation and Cyclic Feature Characterization of Nu-FBMC/OQAM Signals

“…A nonuniform FBMC/OQAM (Nu-FBMC/OQAM) enables flexibility in terms of defining subchannels with arbitrary transmission bandwidths and center frequencies and has the capability to adapt services to different incoming data rates, which is desirable in many applications. Compared to the FBMC/OQAM, the Nu-FBMC/OQAM also offers better reduction of out-ofband emissions in the presence of nonlinear distortions [1].…”

“…The work in [1] considers the implementation of Nu-FBMC/OQAM by extending the FS-FBMC procedure to Nu-FBs by aggregating subchannels of even-spaced and oddspaced uniform FBs to obtain symmetrical and asymmetrical subchannels of Nu-FB.…”