This paper proposes a two-dimensional spreading method in UMTS Long Term Evolution (LTE). Such a method brings additional time-frequency diversity which is beneficial in terms of the ability to decode transmitted data at the receiver site under multipath fading. Additional diversity is provided due to the fact that chips of transmitted signals are spread using a Walsh-Hadamard spreading sequence over several subcarriers as well as over several time-slots simultaneously. A comparison with state-of-the-art LTE downlink transmission is provided. To enable reproducibility and to increase credibility of our results, an open source Vienna LTE simulator is utilized. LTE transmissions with the proposed 2D spreading are tested on several channel models. Simulations show that apart from an Additive White Gaussian Noise channel model, this 2D spreading based method outperforms the throughput performance of standard LTE. At high Signal to Noise Ratio (SNR), the throughput increase in most channel models is higher than 10 %.
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This work has been funded by the Christian Doppler Laboratory for Wireless Technologies for Sustainable Mobility, KATHREINWerke KG, and A1 Telekom Austria AG. The financial support by the Federal Ministry of Economy, Family and Youth and the National Foundation for Research, Technology and Development is gratefully acknowledged. The Grant Agency of Czech Republic grant no. P102/10/P513 “Communication systems combining OFDM and CDMA and their PAPR” is also gratefully acknowledged. The authors would like to thank Josep Colom Ikuno for many fruitful and interesting discussions on this and related topics. The research published in this submission was financially supported by the project CZ.1.07/2.2.00/20.0007 WICOMT of the operational program Education for competitiveness.
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Blumenstein, J., Šimko, M., Marsalek, R. et al. Two Dimensional Signal Spreading in UMTS LTE: Exploiting Time-Frequency Diversity to Increase Throughput. Wireless Pers Commun 71, 1109–1119 (2013). https://doi.org/10.1007/s11277-012-0864-3
- 2D Spreading
- Throughput maximization
- Vienna LTE simulator