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Taheri, T., Mohamad, M., Nilsson, R. & Beek, J. v. (2020). Joint spectral-spatial precoders in MIMO-OFDM transmitters. Signal Processing
Öppna denna publikation i ny flik eller fönster >>Joint spectral-spatial precoders in MIMO-OFDM transmitters
2020 (Engelska)Ingår i: Signal Processing, ISSN 0165-1684, E-ISSN 1872-7557Artikel i tidskrift (Refereegranskat) Epub ahead of print
Abstract [en]

This work studies the joint design of spectral precoding, to avoid spectral out-of-band power emissions, and spatial precoding, to suppress spatial multiuser interference, in MIMO-OFDM systems. In current state-of-art approaches the transmit signals are precoded using two independently designed spectral and spatial precoders. In contrast this paper proposes a joint precoding of the signal to achieve a better performance. We analyse the performance of the proposed precoder in terms of spectral characteristics, system spectral efficiency and transmitter complexity. We show in particular that, interestingly, the proposed joint maximum-ratio precoder has a simple transmitter structure of two separate and consecutive banks of spectral and spatial precoders which in fact can be designed independently, while in case of zero-forcing the off-the-shelf precoders are far from the optimal. The joint zero-forcing precoder has a coupled structure and hence, we can not decompose it.

Nationell ämneskategori
Signalbehandling
Forskningsämne
Signalbehandling
Identifikatorer
urn:nbn:se:ltu:diva-77829 (URN)10.1016/j.sigpro.2020.107538 (DOI)
Forskningsfinansiär
Vetenskapsrådet
Tillgänglig från: 2020-02-24 Skapad: 2020-02-24 Senast uppdaterad: 2020-02-24
Pirinen, P., Saarnisaari, H., Beek, J. v., Matinmikko-Blue, M., Nilsson, R. & Latva-aho, M. (2019). Wireless Connectivity for Remote and Arctic Areas – Food for Thought. In: : . Paper presented at 16th International Symposium on Wireless Communications Systems.
Öppna denna publikation i ny flik eller fönster >>Wireless Connectivity for Remote and Arctic Areas – Food for Thought
Visa övriga...
2019 (Engelska)Konferensbidrag, Publicerat paper (Refereegranskat)
Nationell ämneskategori
Teknik och teknologier
Identifikatorer
urn:nbn:se:ltu:diva-77004 (URN)
Konferens
16th International Symposium on Wireless Communications Systems
Tillgänglig från: 2019-11-30 Skapad: 2019-11-30 Senast uppdaterad: 2019-11-30
Mohamad, M., Nilsson, R. & Beek, J. v. (2018). A Novel Transmitter Architecture for Spectrally-Precoded OFDM. IEEE Transactions on Circuits and Systems Part 1: Regular Papers, 65(8), 2592-2605
Öppna denna publikation i ny flik eller fönster >>A Novel Transmitter Architecture for Spectrally-Precoded OFDM
2018 (Engelska)Ingår i: IEEE Transactions on Circuits and Systems Part 1: Regular Papers, ISSN 1549-8328, E-ISSN 1558-0806, Vol. 65, nr 8, s. 2592-2605Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

Frequency nulling spectral precoding is an approachthat suppresses the out-of-band emission in OFDM systems.In this paper, we discuss the transmitter architecture of thespectrally precoded OFDM systems. We design a novel precoderthat matches the practical implementation of the OFDM modulator.We show that spectral precoding can relax the analog lowpass filtering requirements of the OFDM system transmitter. Weexamine the effect of spectral precoding on the PAPR as wellas the effect of the PA on the spectral precoding suppressionperformance. We also study the compliance of the spectrallyprecoded OFDM transmitter with the 3GPP standardizationmeasures and analyze its computation complexity. At the receiverside, we analyze the in-band interference and BER performanceof the suggested precoding approach.

Ort, förlag, år, upplaga, sidor
IEEE, 2018
Nationell ämneskategori
Teknik och teknologier Signalbehandling
Forskningsämne
Signalbehandling
Identifikatorer
urn:nbn:se:ltu:diva-67847 (URN)10.1109/TCSI.2018.2797527 (DOI)000437882000022 ()2-s2.0-85041808007 (Scopus ID)
Forskningsfinansiär
Swedish Research Council for Environment, Agricultural Sciences and Spatial Planning
Anmärkning

Validerad;2018;Nivå 2;2018-08-08 (rokbeg)

Tillgänglig från: 2018-03-05 Skapad: 2018-03-05 Senast uppdaterad: 2018-12-07Bibliografiskt granskad
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
Öppna denna publikation i ny flik eller fönster >>Quasi-Cyclic Symbol Extensions for Shaping the OFDM Spectrum
2018 (Engelska)Ingår i: IEEE Transactions on Wireless Communications, ISSN 1536-1276, E-ISSN 1558-2248, Vol. 17, nr 10, s. 7054-7066Artikel i tidskrift (Refereegranskat) 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.

Ort, förlag, år, upplaga, sidor
IEEE, 2018
Nationell ämneskategori
Signalbehandling
Forskningsämne
Signalbehandling
Identifikatorer
urn:nbn:se:ltu:diva-70580 (URN)10.1109/TWC.2018.2865566 (DOI)000447047200048 ()
Anmärkning

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

Tillgänglig från: 2018-08-24 Skapad: 2018-08-24 Senast uppdaterad: 2018-12-11Bibliografiskt granskad
Mohamad, M., Nilsson, R. & van de Beek, J. (2017). An SDR-based prototype of spectrally-precoded OFDM. In: EuCNC 2017: European Conference on Networks and Communications. Paper presented at European Conference on Networks and Communications (EuCNC 2017), Oulu, Finland, 12-15 June 2017. Piscataway, NJ: Institute of Electrical and Electronics Engineers (IEEE), Article ID 7980758.
Öppna denna publikation i ny flik eller fönster >>An SDR-based prototype of spectrally-precoded OFDM
2017 (Engelska)Ingår i: EuCNC 2017: European Conference on Networks and Communications, Piscataway, NJ: Institute of Electrical and Electronics Engineers (IEEE), 2017, artikel-id 7980758Konferensbidrag, Publicerat paper (Refereegranskat)
Abstract [en]

Spectrally precoded OFDM is a recent approach that aims for the suppression of the OOB, as well as the in-band gap, emissions in OFDM systems. Theoretically, the technique shows High suppression of the OOB and the in-band gap emissions. Although, practically hardware impairments may limit the precoder's performance. Yet, this demonstration shows that despite the hardware impairments, implemented spectrally precoded OFDM generates emissions tens of decibels less than that of plain OFDM. Therefore, the demonstration proves that communications links are less vulnerable to interference coming from spectrally precoded OFDM signals than to interference coming from plain OFDM signals

Ort, förlag, år, upplaga, sidor
Piscataway, NJ: Institute of Electrical and Electronics Engineers (IEEE), 2017
Nationell ämneskategori
Elektroteknik och elektronik Signalbehandling
Forskningsämne
Signalbehandling
Identifikatorer
urn:nbn:se:ltu:diva-64716 (URN)10.1109/EuCNC.2017.7980758 (DOI)000425922900118 ()2-s2.0-85039935034 (Scopus ID)978-1-5386-3873-6 (ISBN)
Konferens
European Conference on Networks and Communications (EuCNC 2017), Oulu, Finland, 12-15 June 2017
Tillgänglig från: 2017-07-01 Skapad: 2017-07-01 Senast uppdaterad: 2018-12-07Bibliografiskt granskad
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.
Öppna denna publikation i ny flik eller fönster >>Hybrid spectral precoding/windowing for low-latency OFDM
2017 (Engelska)Konferensbidrag, Publicerat paper (Refereegranskat)
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.

Ort, förlag, år, upplaga, sidor
Piscataway, MJ: Institute of Electrical and Electronics Engineers (IEEE), 2017
Serie
IEEE Vehicular Technology Conference Proceedings, ISSN 1550-2252
Nationell ämneskategori
Elektroteknik och elektronik
Identifikatorer
urn:nbn:se:ltu:diva-64717 (URN)10.1109/VTCSpring.2017.8108399 (DOI)000426875801040 ()2-s2.0-85040610539 (Scopus ID)9781509059324 (ISBN)
Konferens
IEEE 85th Vehicular Technology Conference (VTC Spring), Sydney, Australia, 4-7 Juni 2017
Tillgänglig från: 2017-07-01 Skapad: 2017-07-01 Senast uppdaterad: 2018-05-22Bibliografiskt granskad
Nilsson, R. (2016). Activity: An SDR-based prototype of spectrally precoded OFDM (ed.). Paper presented at EAI International Conference on Cognitive Radio Oriented Wireless Networks : 30/05/2016 - 01/06/2016. Paper presented at EAI International Conference on Cognitive Radio Oriented Wireless Networks : 30/05/2016 - 01/06/2016.
Öppna denna publikation i ny flik eller fönster >>Activity: An SDR-based prototype of spectrally precoded OFDM
2016 (Engelska)Konferensbidrag, Publicerat paper (Övrig (populärvetenskap, debatt, mm))
Abstract [en]

OFDM scheme possesses high OOB emission which degrades the spectral efficiency of OFDM systems. Poor spectral efficiency limits the validity of OFDM as a candidate for 5G. Spectrally precoded OFDM is a recent approach that treats the OFDM signal to suppress the out of band (OOB) emission. Although the theoretical results of spectral precoding show very efficient OOB emission suppression (more than 50 dB reduction compared to plain OFDM), practically, hardware impairments limit its performance.We, at Luleå University of Technology, examine the practicality of the suggested approach and show for the first time through this demonstration that despite the hardware impairments, implemented spectral precoded OFDM has OOB emission tens of decibels less than that of plain OFDM. We set up and examine a communication link through which we approve that communication systems are less vulnerable to interference coming from spectrally precoded OFDM signals than to interference coming from plain OFDM signals.

Nationell ämneskategori
Signalbehandling
Forskningsämne
Signalbehandling
Identifikatorer
urn:nbn:se:ltu:diva-41474 (URN)4fbd7b9b-26f7-41b6-a225-964d504474be (Lokalt ID)4fbd7b9b-26f7-41b6-a225-964d504474be (Arkivnummer)4fbd7b9b-26f7-41b6-a225-964d504474be (OAI)
Konferens
EAI International Conference on Cognitive Radio Oriented Wireless Networks : 30/05/2016 - 01/06/2016
Anmärkning
Startdatum: 30/05/2016; Slutdatum: 01/06/2016; Roll: Annat; Typ: Föreläsning / muntligt bidragTillgänglig från: 2016-10-03 Skapad: 2016-10-03 Senast uppdaterad: 2017-12-08Bibliografiskt granskad
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.
Öppna denna publikation i ny flik eller fönster >>Asymmetric Transmit-windowing for low-latency and robust OFDM
2016 (Engelska)Ingår i: Globecom Workshops (GC Wkshps), 2016 IEEE, Piscataway, NJ: IEEE Communications Society, 2016, artikel-id 7848842Konferensbidrag, Publicerat paper (Refereegranskat)
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.

Ort, förlag, år, upplaga, sidor
Piscataway, NJ: IEEE Communications Society, 2016
Serie
IEEE Globecom Workshops, ISSN 2166-0069
Nationell ämneskategori
Teknik och teknologier Signalbehandling
Forskningsämne
Signalbehandling
Identifikatorer
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)
Konferens
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
Tillgänglig från: 2016-11-28 Skapad: 2016-11-28 Senast uppdaterad: 2018-05-22Bibliografiskt granskad
Nilsson, R. & Beek, J. v. (2016). Channel Measurements in an Open-pit Mine using USRPs: 5G – Expect the Unexpected (ed.). In: (Ed.), 2016 IEEE Wireless Communications and Networking Conference: WCNC 2016, Doha, Qatar, 3-7  April 2016. Paper presented at IEEE Wireless Communications and Networking Conference : Workshop on Communications in Extreme Conditions (ComExCon 2016) 03/04/2016 - 06/04/2016 (pp. 212-217). , Article ID 7564672.
Öppna denna publikation i ny flik eller fönster >>Channel Measurements in an Open-pit Mine using USRPs: 5G – Expect the Unexpected
2016 (Engelska)Ingår i: 2016 IEEE Wireless Communications and Networking Conference: WCNC 2016, Doha, Qatar, 3-7  April 2016, 2016, s. 212-217, artikel-id 7564672Konferensbidrag, Publicerat paper (Refereegranskat)
Abstract [en]

In this paper, we describe and analyze the results of a radio channel measurement campaign in an extreme industrial environment; a large open-pit copper mine targeted by next generation’s highly voiced device communications. We present a practical and efficient method to perform robust and high-sensitivity impulse response measurements without a common clock reference using the widely spread USRP hardware. With this technique, we performed channel sounding on a large number of locations within the mine. One important observation is that the radio channel’s impulse response in an open-pit mine can often be more than 10 microseconds long, and much unlike the responses normally associated with Wi-Fi and mobile cellular radio systems, which poses serious design challenges for future 5G radio systems.

Serie
I E E E Wireless Communications and Networking Conference. Proceedings, ISSN 1525-3511
Nationell ämneskategori
Signalbehandling
Forskningsämne
Signalbehandling; Möjliggörande IKT (FOI); Framtidens gruvor (FOI)
Identifikatorer
urn:nbn:se:ltu:diva-28203 (URN)10.1109/WCNC.2016.7564672 (DOI)000388603100036 ()2-s2.0-84989938839 (Scopus ID)1eba75b1-83b0-4282-a967-9f4f131d8c1c (Lokalt ID)978-1-4673-8666-1 (ISBN)1eba75b1-83b0-4282-a967-9f4f131d8c1c (Arkivnummer)1eba75b1-83b0-4282-a967-9f4f131d8c1c (OAI)
Konferens
IEEE Wireless Communications and Networking Conference : Workshop on Communications in Extreme Conditions (ComExCon 2016) 03/04/2016 - 06/04/2016
Anmärkning

Godkänd; 2016-10-19 (andbra)

Tillgänglig från: 2016-09-30 Skapad: 2016-09-30 Senast uppdaterad: 2019-03-04Bibliografiskt granskad
Mohamad, M., Nilsson, R. & Beek, J. v. (2016). Minimum-EVM N-continuous OFDM (ed.). In: (Ed.), 2016 IEEE International Conference on Communications (ICC): Kuala Lumpur, 22-27 May 2016. Paper presented at IEEE International Conference on Communications : 23/05/2016 - 27/05/2016. Piscataway, NJ: IEEE Communications Society, Article ID 7511164.
Öppna denna publikation i ny flik eller fönster >>Minimum-EVM N-continuous OFDM
2016 (Engelska)Ingår i: 2016 IEEE International Conference on Communications (ICC): Kuala Lumpur, 22-27 May 2016, Piscataway, NJ: IEEE Communications Society, 2016, artikel-id 7511164Konferensbidrag, Publicerat paper (Refereegranskat)
Abstract [en]

The N-continuous precoder for the suppression ofOOB emission in OFDM systems that minimizes the EVM isintroduced. We show that the minimum in-band interference dueto the introduced precoding approach is 3 dB less than the inbandinterference of existing N-continuous precoders. Moreover,we introduce a novel practical block precoder that approachesthe performance of the suggested optimal precoder. We analyzethe spectrum of the OFDM signal after block precoding, the inbandinterference due to block precoding and the effect of blockprecoding on the BER. The price to pay for block precoding isthe computational complexity that grows linearly with the blocksize.

Ort, förlag, år, upplaga, sidor
Piscataway, NJ: IEEE Communications Society, 2016
Nyckelord
OFDM, spectrum, out of band emission, in-band interference, Information technology - Signal processing, Informationsteknik - Signalbehandling
Nationell ämneskategori
Signalbehandling
Forskningsämne
Signalbehandling; Möjliggörande IKT (FOI)
Identifikatorer
urn:nbn:se:ltu:diva-31163 (URN)10.1109/ICC.2016.7511164 (DOI)000390993203035 ()2-s2.0-84981306982 (Scopus ID)54014940-6cf4-4e51-974e-dcfdcf2fed88 (Lokalt ID)978-1-4799-6664-6 (ISBN)54014940-6cf4-4e51-974e-dcfdcf2fed88 (Arkivnummer)54014940-6cf4-4e51-974e-dcfdcf2fed88 (OAI)
Konferens
IEEE International Conference on Communications : 23/05/2016 - 27/05/2016
Anmärkning

Godkänd; 2016; 20151105 (jaavan)

Tillgänglig från: 2016-09-30 Skapad: 2016-09-30 Senast uppdaterad: 2018-12-07Bibliografiskt granskad
Organisationer
Identifikatorer
ORCID-id: ORCID iD iconorcid.org/0000-0003-0413-4826

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