Lund University Publications
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Lund University Lund University Publications2000-01-01T00:00+00:001dailyThe Potential of Using Large Antenna Arrays on Intelligent Surfaces
https://lup.lub.lu.se/search/publication/61d4e6ec-7895-43b4-9ba5-6b83e16704f2
Hu, ShaRusek, FredrikEdfors, Ove2017-11-16In this paper, we consider capacities of single-antenna terminals communicating to large antenna arrays that are deployed on surfaces. That is, the entire surface is used as an intelligent receiving antenna array. Under the condition that the surface area is sufficiently large, the received signal after matched-filtering (MF) can be well approximated by an intersymbol interference (ISI) channel where channel taps are closely related to a sinc function. Based on such an approximation, we have derived the capacities for both one-dimensional (terminals on a line) and high dimensional (terminals on a plane or in a cube) terminal-deployments. In particular, we analyze the normalized capacity $\bar{\mathcal{C}}$, measured in nats/s/Hz/m$^2$, under the constraint that the transmit power per m$^2$, $\bar{P}$, is fixed. We show that when the user-density increases, the limit of $\bar{\mathcal{C}}$, achieved as the wavelength $\lambda$ approaches 0, is $\bar{P}/(2N_0)$ nats/s/Hz/m$^2$, where $N_0$ is the spatial power spectral density (PSD) of noise. In addition, we also show that the number of signal dimensions is $2/\lambda$ per meter deployed surface for the one-dimensional case, and $\pi/\lambda^2$ per m$^2$ deployed surface for two and three dimensional terminal-deployments.http://lup.lub.lu.se/record/61d4e6ec-7895-43b4-9ba5-6b83e16704f2http://dx.doi.org/10.1109/VTCSpring.2017.8108330ISBN: 978-1-5090-5932-4 scopus:85040542986engKommunikationssystemThe Potential of Using Large Antenna Arrays on Intelligent Surfacescontributiontobookanthology/conferenceinfo:eu-repo/semantics/conferencePapertextBeyond Massive-MIMO : The Potential of Data-Transmission with Large Intelligent Surfaces
https://lup.lub.lu.se/search/publication/552776ea-89af-4ec4-953d-a0d9716117ad
Hu, ShaRusek, FredrikEdfors, Ove2018-05-15In this paper, we consider the potential of data-transmission in a system with a massive number of radiating and sensing elements, thought of as a contiguous surface of electromagnetically active material. We refer to this as a Large Intelligent Surface (LIS). The "LIS" is a newly proposed concept, which conceptually goes beyond contemporary massive MIMO technology, and arises from our vision of a future where man-made structures are electronically active with integrated electronics and wireless communication making the entire environment "intelligent". Firstly, we consider capacities of single-antenna autonomous terminals communicating to the LIS where the entire surface is used as a receiving antenna-array in a perfect line-of-sight (LOS) propagation environment. Under the condition that the surface-area is sufficiently large, the received signal after a matched-filtering (MF) operation can be closely approximated by a sinc-function-like intersymbol interference (ISI) channel. Secondly, we analyze a normalized capacity measured per unit-surface, for a fixed transmit power per volume-unit with different terminal-deployments. As terminal-density increases, the limit of the normalized capacity [nats/s/Hz/volume-unit] achieved when wavelength <formula><tex>$\lambda$</tex></formula> approaches zero is equal to half of the transmit power per volume-unit divided by noise spatial power spectral density (PSD). Thirdly, we show that the number of independent signal dimensions that can be harvested per meter deployed surface is <formula><tex>$2/\lambda$</tex></formula> for one-dimensional terminal-deployment, and <formula><tex>$\pi/\lambda^{2}$</tex></formula> per square meter for two and three dimensional terminal-deployments. Lastly, we consider implementations of the LIS in the form of a grid of conventional antenna-elements, and show that the sampling lattice that minimizes the surface-area and simultaneously obtains one independent signal dimension for every spent antenna is the hexagonal lattice.http://lup.lub.lu.se/record/552776ea-89af-4ec4-953d-a0d9716117adhttp://dx.doi.org/10.1109/TSP.2018.2816577scopus:85044028460engIEEE Transactions on Signal Processing; 66(10), pp 2746-2758 (2018)ISSN: 1053-587XKommunikationssystem2D samplingHankel transformhexagonal latticeindependent signal dimensionintersymbol interference (ISI)Large intelligent surface (LIS)LatticesLensesline-of-sight (LOS)massive multiinput multi-output (MIMO)MIMO communicationnormalized capacityReceiving antennasSurface treatmentSurface wavesBeyond Massive-MIMO : The Potential of Data-Transmission with Large Intelligent Surfacescontributiontojournal/articleinfo:eu-repo/semantics/articletextA Soft-Output MIMO Detector with Achievable Information Rate based Partial Marginalization
https://lup.lub.lu.se/search/publication/4a1a9cd3-578e-44c8-b184-55bb1afc0caa
Hu, ShaRusek, Fredrik2017-03-15In this paper, we propose a soft-output detector for multiple-input multiple-output (MIMO) channels that utilizes achievable information rate (AIR) based partial marginalization (PM). The proposed AIR based PM (AIR-PM) detector has superior performance compared to previously proposed PM designs and other soft-output detectors such as K-best, while at the same time yielding lower computational complexity, a detection latency that is independent of the number of transmit layers, and straightforward inclusion of soft input information. Using a tree representation of the MIMO signal, the key property of the AIRPM is that the connections among all child layers are broken. Therefore, least-square (LS) estimates used for marginalization are obtained independently and in parallel, which have better quality than the zero-forcing decision feedback (ZF-DF) estimates used in previous PM designs. Such a property of the AIRPM detector is designed via a mismatched detection model that maximizes the AIR. Furthermore, we show that the chain rule holds for the AIR calculation, which facilitates an information theoretic characterization of the AIR-PM detector.http://lup.lub.lu.se/record/4a1a9cd3-578e-44c8-b184-55bb1afc0caahttp://dx.doi.org/10.1109/TSP.2016.2641393scopus:85014949602wos:000395423500019engIEEE Transactions on Signal Processing; 65(6), pp 1622-1627 (2017)ISSN: 1053-587XSignalbehandlingA Soft-Output MIMO Detector with Achievable Information Rate based Partial Marginalizationcontributiontojournal/articleinfo:eu-repo/semantics/articletextSpatial Separation of Closely-Spaced Users in Measured Massive Multi-User MIMO Channels
https://lup.lub.lu.se/search/publication/c2853508-a976-4cb8-b25d-1f37ad514e86
Flordelis, JoseGao, XiangDahman, GhassanRusek, FredrikEdfors, OveTufvesson, Fredrik2015Fully-synchronous measurements of a massive multi-user multiple-input multiple-output (MU-MIMO) radio propagation channel are presented. We evaluate the ability of a massive MIMO system to spatially separate users located close to each other in line-of-sight (LOS) propagation conditions. The system consists of a base-station (BS) antenna array equipped with 64 dual-polarized antenna elements (128 ports) arranged
in a cylindrical configuration, and eight single-antenna users. The users are confined to a five-meter diameter circle and move randomly at pedestrian speeds. The BS antenna array is located on top of a 20 m tall building and has LOS to the users. We examine user separability by studying singular value spread
of the MU-MIMO channel matrix for several subsets of BS antenna array ports, along with sum-rate capacity and achievable sum-rates with both zero-forcing and matched-filtering linear precoders. We also analyze the performance of the user with the lowest rate. Finally, a comparison between the performance offered by the massive MIMO system and that of a conventional MU-MIMO system is provided. To the best of our knowledge, this is the first report of fully-synchronous dynamic measurements of a massive MIMO system. Our investigation shows that even users located close to each other in LOS propagation conditions can be spatially separated in a massive MIMO system.application/pdfhttp://lup.lub.lu.se/record/5154187http://lup.lub.lu.se/search/ws/files/5990411/5154208.pdfscopus:84953717299enginfo:eu-repo/semantics/openAccessElektroteknik och elektronikmulti-user multiple-input multiple-output systemsMU-MIMOmassive MIMOlarge-scale MIMOMIMO channel measurementsspatial separationsingular value spreadsum-rate capacitysum-ratelinear precoderSpatial Separation of Closely-Spaced Users in Measured Massive Multi-User MIMO Channelscontributiontobookanthology/conferenceinfo:eu-repo/semantics/conferencePapertextLinear pre-coding performance in measured very-large MIMO channels
https://lup.lub.lu.se/search/publication/88f20b8a-3aa5-4e76-a9c2-9a8fa7bca97c
Gao, XiangEdfors, OveRusek, FredrikTufvesson, Fredrik2011Wireless communication using very-large multiple-input multiple-output (MIMO) antennas is a new research field, where base stations are equipped with a very large number of antennas as compared to previously considered systems. In theory, as the number of antennas increases, propagation properties that were random before start to become deterministic. Theoretical investigations with independent identically distributed (i.i.d.)\ complex Gaussian (Rayleigh fading) channels and unlimited number of antennas have been done, but in practice we need to know what benefits we can get from very large, but limited, number of antenna elements in realistic propagation environments. In this study we evaluate properties of measured residential-area channels, where the base station is equipped with 128 antenna ports. An important property to consider is the orthogonality between channels to different users, since this property tells us how advanced multi-user MIMO (MU-MIMO) pre-coding schemes we need in the downlink. We show that orthogonality improves with increasing number of antennas, but for two single-antenna users there is very little improvement beyond 20 antennas. We also evaluate sum-rate performance for two linear pre-coding schemes, zero-forcing (ZF) and minimum mean squared-error (MMSE), as a function of the number of base station antennas. Already at 20 base station antennas these linear pre-coding schemes reach 98\% of the optimal dirty-paper coding (DPC) capacity for the measured channels.application/pdfhttp://lup.lub.lu.se/record/2199294http://lup.lub.lu.se/search/ws/files/5499580/2541120.pdfwos:000298891500479scopus:83755161752enginfo:eu-repo/semantics/openAccessElektroteknik och elektronikLinear pre-coding performance in measured very-large MIMO channelscontributiontobookanthology/conferenceinfo:eu-repo/semantics/conferencePapertextScaling up MIMO: opportunities and challenges with very large arrays
https://lup.lub.lu.se/search/publication/a897be1f-e44f-466d-bbdc-ed11cc9cb14d
Rusek, FredrikPersson, DanielLau, Buon KiongLarsson, Erik G.Marzetta, Thomas L.Edfors, OveTufvesson, Fredrik2013application/pdfhttp://lup.lub.lu.se/record/2174140http://dx.doi.org/10.1109/MSP.2011.2178495http://lup.lub.lu.se/search/ws/files/4313105/5323005.pdfwos:000315349700006scopus:85032752174enginfo:eu-repo/semantics/openAccessIEEE Signal Processing Magazine; 30(1), pp 40-60 (2013)ISSN: 1053-5888Elektroteknik och elektronikScaling up MIMO: opportunities and challenges with very large arrayscontributiontojournal/articleinfo:eu-repo/semantics/articletextMeasured propagation characteristics for very-large MIMO at 2.6 GHz
https://lup.lub.lu.se/search/publication/351f1fde-abe4-4327-8a00-7a8f076a8563
Gao, XiangTufvesson, FredrikEdfors, OveRusek, Fredrik2012application/pdfhttp://lup.lub.lu.se/record/3288101http://lup.lub.lu.se/search/ws/files/3368853/3288127.pdfwos:000320768400054scopus:84876261871enginfo:eu-repo/semantics/openAccesspp 295-299 (2012)ISSN: 1058-6393Elektroteknik och elektronikMeasured propagation characteristics for very-large MIMO at 2.6 GHzcontributiontobookanthology/conferenceinfo:eu-repo/semantics/conferencePapertextMassive MIMO performance evaluation based on measured propagation data
https://lup.lub.lu.se/search/publication/237c181b-16ec-49bd-883a-9dbfcf401339
Gao, XiangEdfors, OveRusek, FredrikTufvesson, Fredrik2015Massive MIMO, also known as very-large MIMO or large-scale antenna systems, is a new technique that potentially can offer large network capacities in multi-user scenarios. With a massive MIMO system, we consider the case where a base station equipped with a large number of antenna elements simultaneously serves multiple single-antenna users in the same time-frequency resource. So far, investigations are mostly based on theoretical channels with independent and identically distributed (i.i.d.) complex Gaussian coefficients, i.e., i.i.d. Rayleigh channels. Here, we investigate how massive MIMO performs in channels measured in real propagation environments. Channel measurements were performed at 2.6 GHz using a virtual uniform linear array (ULA) which has a physically large aperture, and a practical uniform cylindrical array (UCA) which is more compact in size, both having 128 antenna ports. Based on measurement data, we illustrate channel behavior of massive MIMO in three representative propagation conditions, and evaluate the corresponding performance. The investigation shows that the measured channels, for both array types, allow us to achieve performance close to that in i.i.d. Rayleigh channels. It is concluded that in real propagation environments we have characteristics that can allow for efﬁcient use of massive MIMO, i.e., the theoretical advantages of this new technology can also be harvested in real channels.application/pdfhttp://lup.lub.lu.se/record/5218941http://dx.doi.org/10.1109/TWC.2015.2414413http://lup.lub.lu.se/search/ws/files/3145420/5323121.pdfwos:000357805200030scopus:84937134074enginfo:eu-repo/semantics/openAccessIEEE Transactions on Wireless Communications; 14(7), pp 3899-3911 (2015)ISSN: 1536-1276Elektroteknik och elektroniksingular value spreadangular power spectrachannel capacityvery-large MIMOMassive MIMOchannel measurementsmulti-user MIMO5GMassive MIMO performance evaluation based on measured propagation datacontributiontojournal/articleinfo:eu-repo/semantics/articletextOn the probability of non-shared multipath clusters in cellular networks
https://lup.lub.lu.se/search/publication/b3a73ed1-d89c-4f44-92ac-bf28fe7ce66c
Dahman, GhassanRusek, FredrikZhu, MeifangTufvesson, Fredrik2015In Space Division Multiple Access (SDMA) systems, users are separated based on their positions. The base-station (BS) signals typically reach the users through multipath clusters. The goal of this work is to find the probability that a randomly selected user will receive the signal from the BS via at least one nonshared (by any other user) multipath cluster. This probability, referred to as PSuccess, provides (under some conditions) the limit of the probability that the BS is able to communicate successfully with a randomly selected user using SDMA without causing significant interference to other users. In order to find PSuccess, we first derive a model describing the probability distribution function (pdf) of the non-overlapping area of a set of circles, that have the same radius and are spatially distributed according to a Poisson distribution. Then, the proposed model for this pdf is used to express PSuccess as a function of the user’s intensity and the clusters’ intensity. Simulations, using the COST 2100 model, for outdoor and indoor scenarios, are used to validate the derived expression for PSuccess with a very good agreement, where the maximum error was 0:04.http://lup.lub.lu.se/record/5218992http://dx.doi.org/10.1109/LWC.2015.2388531scopus:84927711190wos:000373740000013engIEEE Wireless Communications Letters; (99) (2015)ISSN: 2162-2345Elektroteknik och elektronikOn the probability of non-shared multipath clusters in cellular networkscontributiontojournal/letterinfo:eu-repo/semantics/articletext