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Publications (7 of 7) Show all publications
Taheri, T. (2020). Precoding and Asymmetric Windowing of OFDM Signals: Energy Confinement in Time, Frequency and Space. (Doctoral dissertation). Luleå University of Technology
Open this publication in new window or tab >>Precoding and Asymmetric Windowing of OFDM Signals: Energy Confinement in Time, Frequency and Space
2020 (English)Doctoral thesis, comprehensive summary (Other academic)
Place, publisher, year, edition, pages
Luleå University of Technology, 2020
Series
Doctoral thesis / Luleå University of Technology 1 jan 1997 → …, ISSN 1402-1544
National Category
Signal Processing
Research subject
Signal Processing
Identifiers
urn:nbn:se:ltu:diva-76964 (URN)978-91-7790-510-3 (ISBN)978-91-7790-511-0 (ISBN)
Public defence
2020-03-03, E632, Luleå, 13:00 (English)
Opponent
Supervisors
Available from: 2019-11-29 Created: 2019-11-29 Last updated: 2020-02-04Bibliographically approved
Taheri, T., Nilsson, R. & Beek, J. v. (2018). Quasi-Cyclic Symbol Extensions for Shaping the OFDM Spectrum. IEEE Transactions on Wireless Communications, 17(10), 7054-7066
Open this publication in new window or tab >>Quasi-Cyclic Symbol Extensions for Shaping the OFDM Spectrum
2018 (English)In: IEEE Transactions on Wireless Communications, ISSN 1536-1276, E-ISSN 1558-2248, Vol. 17, no 10, p. 7054-7066Article in journal (Refereed) Published
Abstract [en]

N-continuous orthogonal frequency division multiplexing (OFDM) is a promising solution to the outof- band (OOB) emission issue in OFDM systems where the Nth-order continuity between OFDM symbols leads to lower OOB emission than the plain OFDM, however, high self-interference in such systems is an obstacle. In this paper we propose a new class of quasi-cyclic symbol extensions which makes the OFDM system N- continuous. The new extension leads to low OOB emission while the additive interference is less than other N-continuous OFDM systems. Moreover, we propose a general analysis of the spectrum and interference that occurs in a linear precoded OFDM system. The framework is applicable to many N-continuous OFDM systems including our proposed method.

Place, publisher, year, edition, pages
IEEE, 2018
National Category
Signal Processing
Research subject
Signal Processing
Identifiers
urn:nbn:se:ltu:diva-70580 (URN)10.1109/TWC.2018.2865566 (DOI)000447047200048 ()
Note

Validerad;2018;Nivå 2;2018-10-10 (inah)

Available from: 2018-08-24 Created: 2018-08-24 Last updated: 2018-12-11Bibliographically approved
Tayebeh, T., Nilsson, R. & van de Beek, J. (2017). Hybrid spectral precoding/windowing for low-latency OFDM. In: : . Paper presented at IEEE 85th Vehicular Technology Conference (VTC Spring), Sydney, Australia, 4-7 Juni 2017. Piscataway, MJ: Institute of Electrical and Electronics Engineers (IEEE), Article ID 8108399.
Open this publication in new window or tab >>Hybrid spectral precoding/windowing for low-latency OFDM
2017 (English)Conference paper, Published paper (Refereed)
Abstract [en]

In this paper we present a joint precoded and windowed OFDM system. This new hybrid method provides flexibility to suppress the out-of band (OOB) emission in non-contiguous OFDM systems used in cognitive radio. This method also provides the possibility of shortening the cyclic prefix without sacrificing the OOB emission or increasing the additional interference which is the case in low-latency future systems.

Place, publisher, year, edition, pages
Piscataway, MJ: Institute of Electrical and Electronics Engineers (IEEE), 2017
Series
IEEE Vehicular Technology Conference Proceedings, ISSN 1550-2252
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:ltu:diva-64717 (URN)10.1109/VTCSpring.2017.8108399 (DOI)000426875801040 ()2-s2.0-85040610539 (Scopus ID)9781509059324 (ISBN)
Conference
IEEE 85th Vehicular Technology Conference (VTC Spring), Sydney, Australia, 4-7 Juni 2017
Available from: 2017-07-01 Created: 2017-07-01 Last updated: 2018-05-22Bibliographically approved
Taheri, T. (2017). Revisiting the OFDM Guard Interval for Reduced Interference and Out-of-Band Emission. (Licentiate dissertation). Luleå University of Technology
Open this publication in new window or tab >>Revisiting the OFDM Guard Interval for Reduced Interference and Out-of-Band Emission
2017 (English)Licentiate thesis, comprehensive summary (Other academic)
Place, publisher, year, edition, pages
Luleå University of Technology, 2017
National Category
Signal Processing
Identifiers
urn:nbn:se:ltu:diva-65700 (URN)978-91-7583-965-3 (ISBN)978-91-7583-966-0 (ISBN)
Presentation
2017-11-13, A3101a, Luleå tekniska universitet, 10:00 (English)
Available from: 2017-09-18 Created: 2017-09-18 Last updated: 2018-05-22Bibliographically approved
Taheri, T., Nilsson, R. & Beek, J. v. (2016). Asymmetric Transmit-windowing for low-latency and robust OFDM. In: Globecom Workshops (GC Wkshps), 2016 IEEE: . Paper presented at IEEE International Conference on Global Communications (GLOBECOM 2016), Third International Workshop on Ultra-Reliable and Low-Latency Communications in Wireless Networks (URLLC), Washington DC, USA, 4-8 December 2016. Piscataway, NJ: IEEE Communications Society, Article ID 7848842.
Open this publication in new window or tab >>Asymmetric Transmit-windowing for low-latency and robust OFDM
2016 (English)In: Globecom Workshops (GC Wkshps), 2016 IEEE, Piscataway, NJ: IEEE Communications Society, 2016, article id 7848842Conference paper, Published paper (Refereed)
Abstract [en]

In the content of low-latency 5G systems we revisit in this paper the question of shortening the cyclic prefix in windowed OFDM system without sacrificing OOB power emissions or increasing the ISI and ICI. Based on interference power analysis we propose a new asymmetric window which provides 30 percent cyclic prefix length reduction without increasing adjacent-channel interference power or channel-induced ISI/ICI.

Place, publisher, year, edition, pages
Piscataway, NJ: IEEE Communications Society, 2016
Series
IEEE Globecom Workshops, ISSN 2166-0069
National Category
Engineering and Technology Signal Processing
Research subject
Signal Processing
Identifiers
urn:nbn:se:ltu:diva-60739 (URN)10.1109/GLOCOMW.2016.7848842 (DOI)000401921400045 ()2-s2.0-85015870699 (Scopus ID)978-1-5090-2482-7 (ISBN)
Conference
IEEE International Conference on Global Communications (GLOBECOM 2016), Third International Workshop on Ultra-Reliable and Low-Latency Communications in Wireless Networks (URLLC), Washington DC, USA, 4-8 December 2016
Available from: 2016-11-28 Created: 2016-11-28 Last updated: 2018-05-22Bibliographically approved
Taheri, T., Mohamad, M., Nilsson, R. & Beek, J. v. Joint spectral-spatial precoders in massive-MIMO OFDM transmitters.
Open this publication in new window or tab >>Joint spectral-spatial precoders in massive-MIMO OFDM transmitters
(English)In: Article in journal (Refereed) Submitted
Abstract [en]

In this paper we propose novel joint spectral-spatial precoders for large-antennaOFDM systems that suppress both spatial multi-user interference and spectral out-ofbandpower emissions. We analyse the performance of the proposed precoder in termsof spectral characteristics, system sum-rate and transmitter complexity. We show inparticular that, interestingly, the proposed joint maximum-ratio precoder has a simpletransmitter structure of two separate and consecutive banks of spectral and spatialprecoders.

National Category
Signal Processing
Identifiers
urn:nbn:se:ltu:diva-71967 (URN)
Funder
Swedish Research Council
Available from: 2018-12-07 Created: 2018-12-07 Last updated: 2018-12-07
Mohamad, M., Taheri, T., Nilsson, R. & Beek, J. v. Subspace-precoded OFDM with low Out-of-Band Emissions:it will work.
Open this publication in new window or tab >>Subspace-precoded OFDM with low Out-of-Band Emissions:it will work
(English)Manuscript (preprint) (Other academic)
Abstract [en]

Today’s multicarrier transmitters, deployed in essentially all communications radio equipment we use(phones, TV’s, computers, etc.), contain means to avoid undesired out-of-band power emissions. Standards and regulations typically restrict the levels of these emissions in order to allow for an efficient use of the radio spectrum. Radio vendors deploy well-established algorithms such as low-pass filtering or windowing to satisfy these regulations. A new approach, specifically applicable to OFDM systems, known as spectralprecoding, has been studied during the last decade. In particular, subspace precoding has attracted theinterest of academia, for its elegance, and despite a few adamant disadvantages. Recent advances now provide a breakthrough: subspace precoding is now a viable alternative to today’s algorithms.

National Category
Signal Processing
Identifiers
urn:nbn:se:ltu:diva-71969 (URN)
Funder
Swedish Research Council
Available from: 2018-12-07 Created: 2018-12-07 Last updated: 2018-12-07
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0003-1711-8606

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