Pre-equalized faster than Nyquist transmission for 5G cellular microwave backhaul

Microwave backhaul links can nowadays deliver rather impressive throughput, however 5G systems will require further higher efficiencies and a promising solution is the so-called faster than Nyqust (FTN) transmission. A FTN communication is obtained when the Nyquist inter-symbol interference (ISI) criterion is not respected because the transmission rate is higher than that for which the shaping filter is designed. While increasing the achievable rate, the complexity increase has up to now discouraged application of FTN in practical systems. In this paper, we propose to compensate for the ISI by means of a non-linear precoding strategy, i.e. the Tomlinson-Harashima precoder (THP), in turn eliminating the need for costly equalizations at the receiver. We characterize the performance of the proposed FTN system by deriving analytical bounds on the achievable rates of the transmissions over a FTN microwave link using high-order modulations and capacity achieving codes. The proposed solution is capacity-achieving at high SNR (which is the operating regime of backhaul microwave links) and has a complexity that does not increase with the density of the constellation. Numerical results show the effectiveness of the THP-FTN solution paving the way towards its implementations on microwave links.

[1]  Fredrik Rusek,et al.  Faster-Than-Nyquist Signaling , 2013, Proceedings of the IEEE.

[2]  Fredrik Rusek,et al.  Receivers for Faster-than-Nyquist signaling with and without turbo equalization , 2008, 2008 IEEE International Symposium on Information Theory.

[3]  Shinya Sugiura,et al.  Frequency-Domain Equalization of Faster-than-Nyquist Signaling , 2013, IEEE Wireless Communications Letters.

[4]  Yong Jin Daniel Kim,et al.  Information rates of cyclostationary faster-than-nyquist signaling , 2011, 2011 12th Canadian Workshop on Information Theory.

[5]  Costas N. Georghiades,et al.  Exploiting faster-than-Nyquist signaling , 2003, IEEE Trans. Commun..

[6]  H. Miyakawa,et al.  Matched-Transmission Technique for Channels With Intersymbol Interference , 1972, IEEE Trans. Commun..

[7]  Yuehong Shen,et al.  Precoding based on matrix decomposition for faster-than-Nyquist signaling , 2015, 2015 IEEE 5th International Conference on Electronics Information and Emergency Communication.

[8]  Nevio Benvenuto,et al.  Fractionally spaced non-linear equalization of faster than Nyquist signals , 2014, 2014 22nd European Signal Processing Conference (EUSIPCO).

[9]  Li Tan,et al.  6 – Finite impulse response filter design , 2013 .

[10]  Nevio Benvenuto,et al.  Algorithms for Communications Systems and their Applications , 2021 .

[11]  Fredrik Rusek,et al.  Constrained Capacities for Faster-Than-Nyquist Signaling , 2009, IEEE Transactions on Information Theory.

[12]  Dario Fertonani,et al.  Time-frequency packing for linear modulations: spectral efficiency and practical detection schemes , 2009, IEEE Transactions on Communications.

[13]  Andrew J. Viterbi,et al.  Error bounds for convolutional codes and an asymptotically optimum decoding algorithm , 1967, IEEE Trans. Inf. Theory.

[14]  Yong Jin Daniel Kim,et al.  On Spectrum Broadening of Pre-Coded Faster-Than-Nyquist Signaling , 2010, 2010 IEEE 72nd Vehicular Technology Conference - Fall.

[15]  R. Venkatesan,et al.  Tomlinson-Harashima precoding with soft detection for faster than Nyquist DP-16QAM coherent optical systems , 2015, 2015 Optical Fiber Communications Conference and Exhibition (OFC).

[16]  Frank Schaich,et al.  A reduced complexity receiver for multi-carrier faster-than-Nyquist signaling , 2013, 2013 IEEE Globecom Workshops (GC Wkshps).

[17]  Fredrik Rusek,et al.  Non Binary and Precoded Faster Than Nyquist Signaling , 2008, IEEE Transactions on Communications.