Project description
Orthogonal Frequency Division Multiplexing (OFDM) is currently the dominating digital transmission technique in most of the modern broadband wireless and wired communication systems. One of the drawbacks of classical OFDM is that up to 20% of the transmit energy is wasted for so called guard intervals (GIs), which are placed between successive OFDM symbols to cope with the effects of multipath propagation. These guard intervals are typically built by random, data dependent sequences. In Unique Word OFDM (UW-OFDM), which has been developed by the involved project partners, the guard interval is built of a deterministic - the so-called unique word. This sequence provides the same advantages as the usual cyclic prefix GI (diagonalization of the channel matrix, prevention of intersymbol interference), but can additionally be designed to optimally meet synchronization and estimation tasks. Furthermore, most importantly, and different to almost all block based signaling schemes it entails the introduction of a certain redundancy in the frequency domain. This redundancy can be exploited beneficially to enhance range, reliability, capacity or battery lifespan. In this sense, UW-OFDM transforms the usually disregarded guard interval into a multi purpose sequence, thus tackling the well-known inefficiency problem of guard intervals in current communication systems. Moreover, adapting the UW and therefore the GI length to different channel conditions will not impact the DFT length and thus keeps relevant processing chain structures untouched. Hence, UW-OFDM allows supporting a wide range of communication scenarios while ensuring high efficiency.
Ph.D. Project Facts
ISP Research Team
Christian Hofbauer
Alexander Onic
Mario Huemer, opens in new window
Duration
Sept. 2013 - Apr. 2016
Publications
20) Hofbauer C., Böck C., Huemer M. "From Dedicated Redundant Subcarriers to Distributed Redundancy in UW-OFDM," in Proceedings of the ASILOMAR Conference on Signals, Systems, and Computers, IEEE, 2016.
19) Alexander Onic, Mario Huemer, “Noise Interpolation for Unique Word OFDM,” In the IEEE Signal Processing Letters, Vol. 21, No. 7, pp. 814-818 (ISSN: 1070-9908, DOI: 10.1109/LSP.2014.2317512 ) PDF, opens a file.
18) Mario Huemer, Alexander Onic, Christian Hofbauer, Stefan Trampitsch, "Widely Linear Data Estimation for Unique Word OFDM“, In the Proceedings of the ASILOMAR Conference on Signals, Systems, and Computers, Pacific Grove, USA, pp. 1934-1938, November 2013 (ISBN: 978-1-4799-2388-5 , IEEE Catalog Number: CFP13431-CDR) "PDF, opens a file.
17) Mario Huemer, Christian Hofbauer, Alexander Onic, Johannes B. Huber, "Design and analysis of UW-OFDM signals," In the AEÜ - International Journal of Electronics and Communications (2014), ISSN 1434-8411, http://dx.doi.org/10.1016/j.aeue.2014.04.018 , opens an external URL in a new window, PDF, opens an external URL in a new window
16) Haselmayr W., Hofbauer C., Etzlinger B., Springer A., Huemer M.: "Iterative Detection for Unique Word OFDM", in: IEEE Global Communications Conference (GLOBECOM 2014), Page(s) 3361-3366, 2014.
15) Christian Hofbauer, Mario Huemer, “A Study of Data Rate Equivalent UW-OFDM and CP-OFDM Concepts,“ In the Proceedings of the ASILOMAR Conference on Signals, Systems, and Computers, Pacific Grove, USA, pp. 168-172, November 2012 (ISBN: 978-1-4673-5051-8 , DOI: 10.1109/ACSSC.2012.6488983) . Accepted Version, opens a file
14) Alexander Onic, Andreas Schenk, Mario Huemer, Johannes B. Huber, “Soft-Output Sphere Detection for Coded Unique Word OFDM,” In the Proceedings of the ASILOMAR Conference on Signals, Systems, and Computers, Pacific Grove, USA, pp. 138-142, November 2012 (ISBN: 978-1-4673-5051-8 , DOI: 10.1109/ACSSC.2012.6488976) . Accepted Version, opens an external URL in a new window
13) Mario Huemer, Christian Hofbauer, Alexander Onic, Johannes B. Huber, “On the Exploitation of the Redundant Energy in UW-OFDM: LMMSE versus Sphere Detection,” In the IEEE Signal Processing Letters, Vol. 19, No. 6, pp. 340-343, June 2012 (ISSN: 1070-9908, DOI: 10.1109/LSP.2012.2194737) . Accepted Version, opens a file
12) Johannes B. Huber, Jakob Rettelbach, Mathis Seidl, Mario Huemer, “Signal Shaping for Unique Word OFDM by Selected Mapping, opens a file,” In the Proceedings of the European Wireless Conference (EW 2012), Poznan, Poland, 8 pages, April 2012 (ISBN: 978-3-8008-3426-9), Invited Paper.
11) Mario Huemer, Christian Hofbauer, Johannes B. Huber, "Non-Systematic Complex Number RS Coded OFDM by Unique Word Prefix," In the IEEE Transactions on Signal Processing, Vol. 60, No. 1, pp. 285-299, January 2012, (ISSN: 1053-587X, DOI: 10.1109/TSP.2011.2168522) . Accepted Version, opens a file
10) Mario Huemer, Alexander Onic, Christian Hofbauer, “Classical and Bayesian Linear Data Estimators for Unique Word OFDM,” In the IEEE Transactions on Signal Processing, Vol. 59, No. 12, pp. 6073-6085, December 2011 (ISSN: 1053-587X, DOI: 10.1109/TSP.2011.2164912) . Accepted Version, opens an external URL in a new window
9) Alexander Onic, Mario Huemer, “Sphere Decoding for Unique Word OFDM,” In the Proceedings of the IEEE Global Communications Conference (GLOBECOM 2011), Houston, USA, 5 pages, December 2011 (ISBN: 978-1-4244-9268-8 bzw.. 978-1-4244-9267-1 ). Accepted Version, opens a file
8) Mario Huemer, Alexander Onic, Christian Hofbauer, “Linear Data Estimators for UW-OFDM: Classical and Bayesian Approaches, opens a file,” In the Proceedings of the European Signal Processing Conference (EUSIPCO 2011), Barcelona, Spain, pp. 1613-1617, August 2011 (ISSN: 2076-1465).
7) Alexander Onic, Mario Huemer, “Limiting the Complexity of Sphere Decoding for UW-OFDM, opens a file,” In the Proceedings of the 16th International OFDM Workshop, Hamburg, Germany, 5 pages, September 2011.
6) Alexander Onic, Mario Huemer, “Direct vs. Two-Step Approach for Unique Word Generation in UW-OFDM, opens an external URL in a new window,” In the Proceedings of the 15th International OFDM-Workshop, Hamburg, Germany, pp. 145-149, September 2010.
5) Mario Huemer, Christian Hofbauer, Johannes B. Huber, “Unique Word Prefix in SC/FDE and OFDM: A Comparison,” In the Proceedings of the IEEE GLOBECOM 2010 Workshop on Broadband Single Carrier and Frequency Domain Communications (BSCFDC 2010), Miami, USA, pp. 1321-1326, December 2010 (ISBN: 978-1-4244-8864-3 , IEEE catalog number: CFP1000E-CDR). Accepted Version, opens a file
4) Christian Hofbauer, Mario Huemer, Johannes B. Huber, “On the Impact of Redundant Subcarrier Energy Optimization in UW-OFDM,” In the Proceedings of the 4th International Conference on Signal Processing and Communication Systems (ICSPCS 2010), Gold Coast, Australia, 6 pages, December 2010 (ISBN: 978-1-4244-7906-1 , IEEE Catalog Number: CFP1090G-USB). Accepted Version, opens a file
3) Mario Huemer, Christian Hofbauer, Johannes B. Huber, “Complex Number RS Coded OFDM with Systematic Noise in the Guard Interval,” In the Proceedings of the Asilomar Conference on Signals, Systems, and Computers, Pacific Grove, USA, pp. 1023-1028, November 2010 (ISBN: 978-1-4244-9720-1 , ISSN: 1058-6393, IEEE Catalog Number: CFP10431-CDR). Accepted Version, opens a file
2) Christian Hofbauer, Mario Huemer, Johannes B. Huber, “Coded OFDM by Unique Word Prefix,” In the Proceedings of the IEEE International Conference on Communication Systems (IEEE ICCS' 2010), Singapore, 5 pages, November 2010 (ISBN: 978-1-4244-7005-1 , IEEE Catalog Number: CFP10806-CDR). Accepted Version, opens a file
1) Mario Huemer, Christian Hofbauer, Johannes B. Huber, “The Potential of Unique Words in OFDM, opens a file,” In the Proceedings of the 15th International OFDM-Workshop, Hamburg, Germany, pp. 140-144, September 2010.
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