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© 2014 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works. ; [EN] Current cellular technologies are based on the concept of coherent communication, in which the channel matrix used for demodulation is estimated via reference or pilot signals. Coherent systems, however, involve a significant increase of the signalling overhead, especially when the number of transmission points is increased or when the mobile channel changes rapidly, which motivates the use of non-coherent techniques. This letter extends the use of non-coherent communications to a multi-user (MU) multiple-input multiple-output (MIMO) framework by combining superposition coding with a reduced-complexity detection method. Numerical results confirm that our scheme achieves higher user rates than non-coherent MU transmission based on time multiplexing. In addition to the well-known sum-rate gain of MU systems, an extra performance gain given by downlink non-coherent MU communication is shown and qualitatively justified. ; This work was performed in the framework of the FP7 project ICT-317669 METIS, supported in part by the European Union. The authors would like to acknowledge the contributions of their colleagues in METIS, although the views expressed are those of the authors and do not necessarily represent the project. The associate editor coordinating the review of this manuscript and approving it for publication was Prof. Chandra Ramabhadra Murthy. ; Roger Varea, S.; Calabuig Soler, D.; Cabrejas Peñuelas, J.; Monserrat Del Río, JF. (2014). Multi-user non-coherent detection for downlink MIMO communication. IEEE Signal Processing Letters. 21(10):1225-1229. https://doi.org/10.1109/LSP.2014.2330854 ; S ; 1225 ; 1229 ; 21 ; 10

[EN] In the context of multi-hop cellular communications, user equipment devices (UEs) with relaying capabilities provide a virtual infrastructure that can enhance the cell spectral efficiency. UE relays, which are generally transparent to the destination user and lack channel state information, mainly operate in an open-loop mode. Most open-loop transmission techniques for relaying are based on orthogonal space-time block coding (OSTBC), which offers a good trade-off between performance and complexity. In this paper, we consider the concept of multi-functional multiple-input multiple-output (MIMO) transmission, which combines OSTBC with beamforming techniques. This concept is applied to networks with multiple relays, which can offer a high number of antennas to implement multi-functional MIMO techniques. The proposed schemes are shown to reduce the bit error rate of the destination user with respect to a direct transmission from the base station (BS). Furthermore, the multi-functional setup exhibits better performance than conventional OSTBC at high transmission rates. ; This work was performed in the framework of the FP7 project ICT-317669 METIS, which is partly funded by the European Union. The authors would like to acknowledge the contributions of their colleagues in METIS, although the views expressed are those of the authors and do not necessarily represent the project. ; Roger Varea, S.; Calabuig Soler, D.; Monserrat Del Río, JF.; Cardona Marcet, N. (2014). Multi-functional MIMO communication in multi-hop cellular systems. EURASIP Journal on Advances in Signal Processing. 2014(165):1-9. https://doi.org/10.1186/1687-6180-2014-165 ; S ; 1 ; 9 ; 2014 ; 165 ; Timus B, Fallgren M (Eds): In D1.1: Scenarios, requirements and KPIs for 5G mobile and wireless system. Project deliverable, ICT-317669-METIS. 2013. ; Zheng K, Fan B, Ma Z, Liu G, Shen X, Wang W: Multihop cellular networks toward LTE-advanced. IEEE Veh. Tech. Mag 2009, 4(3):40-47. ; Gozalvez J, Coll-Perales B: Experimental evaluation of multihop cellular ...

[EN] The evolution of LTE towards 5G has started and different research projects and institutions are in the process of verifying new technology components through simulations. Coordination between groups is strongly recommended and, in this sense, a common definition of test cases and simulation models is needed. The scope of this paper is to present a realistic channel model for urban macrocell scenarios. This model is map-based and takes into account the layout of buildings situated in the area under study. A detailed description of the model is given together with a comparison with other widely used channel models. The benchmark includes a measurement campaign in which the proposed model is shown to be much closer to the actual behavior of a cellular system. Particular attention is given to the outdoor component of the model, since it is here where the proposed approach is showing main difference with other previous models. ; This work was performed in the framework of the FP7 project ICT-317669 METIS, which is partly funded by the European Union. The authors would like to acknowledge the contributions of their colleagues in METIS, although the views expressed are those of the authors and do not necessarily represent the project. ; Monserrat Del Río, JF.; Inca Sánchez, SA.; Calabuig Gaspar, J.; Martín-Sacristán, D. (2015). Map-based channel model for urban macrocell propagation scenarios. International Journal of Antennas and Propagation. 2015(172501):1-5. https://doi.org/10.1155/2015/172501 ; S ; 1 ; 5 ; 2015 ; 172501

[EN] Current cellular technologies are based on the concept of coherent communication, in which the channel matrix used for demodulation is estimated via reference or pilot signals. Coherent systems involve a significant increase of the signaling overhead, either when the number of Transmission Points (TP) is increased, due to the use of Coordinated Multipoint transmission/reception (CoMP) with Multiple-Input Multiple-Output (MIMO) processing, or when mobile channel changes rapidly. Another disadvantage of coherent communications is the performance degradation caused by channel estimation errors. Both drawbacks of coherent communication motivate the use of non-coherent techniques. Although there are many theoretical studies on the performance of non-coherent schemes in MIMO systems, their impact on real-world cellular systems is still unknown. This paper focuses on bringing non-coherent techniques into practical systems using CoMP and/or MIMO processing. ; This work was performed in the framework of the FP7project ICT-317669 METIS, which is partly funded by the European Union. ; Roger Varea, S.; Cabrejas Peñuelas, J.; Calabuig Soler, D.; Monserrat Del Río, JF.; Fouad, Y.; Gohary, RH.; Yanikomeroglu, H. (2014). Non-coherent MIMO Communication for the 5th Generation Mobile: Overview and Practical Aspects. Waves. 6:5-15. http://hdl.handle.net/10251/52904 ; S ; 5 ; 15 ; 6

6161 6170 4 ; S ; [EN] This paper investigates the use of non-coherent communication techniques for open-loop transmission over temporally-correlated Rayleigh-fading MIMO channels. These techniques perform data detection without knowing the instantaneous channel coefficients. Three non-coherent Multiple Input Multiple Output (MIMO) schemes, namely, differential unitary space-time modulation, differential space-time block code, and Grassmannian signaling, are compared with several state-of-the-art training-based coherent schemes. This paper shows that the non-coherent schemes are meaningful alternatives to training-based communication, specially as the number of transmit antennas increases. In particular, for more than two transmit antennas, non-coherent communication provides a clear advantage in medium to high mobility scenarios. This work was supported in part by the Ministerio de Economia y Competitividad, Spain, under Grant TEC2014-60258-C2-1-R, in part by the European Regional Development Fund, in part by the European Union through the H2020 Project METIS-II under Grant 671680, in part by Huawei Canada Company, Ltd., and in part by the Ontario Ministry of Economic Development and Innovation's through the Ontario Research Fund-Research Excellence Program. Cabrejas Peñuelas, J.; Roger Varea, S.; Calabuig Soler, D.; Fouad, YMM.; Gohary, RH.; Monserrat Del Río, JF.; Yanikomeroglu, H. (2016). Non-Coherent Open-Loop MIMO Communications Over Temporally-Correlated Channels. IEEE Access. 4:6161-6170. https://doi.org/10.1109/ACCESS.2016.2580680

[EN] This paper investigates the use of non-coherent communication techniques for open-loop transmission over temporally-correlated Rayleigh-fading MIMO channels. These techniques perform data detection without knowing the instantaneous channel coefficients. Three non-coherent Multiple Input Multiple Output (MIMO) schemes, namely, differential unitary space-time modulation, differential space-time block code, and Grassmannian signaling, are compared with several state-of-the-art training-based coherent schemes. This paper shows that the non-coherent schemes are meaningful alternatives to training-based communication, specially as the number of transmit antennas increases. In particular, for more than two transmit antennas, non-coherent communication provides a clear advantage in medium to high mobility scenarios. ; This work was supported in part by the Ministerio de Economia y Competitividad, Spain, under Grant TEC2014-60258-C2-1-R, in part by the European Regional Development Fund, in part by the European Union through the H2020 Project METIS-II under Grant 671680, in part by Huawei Canada Company, Ltd., and in part by the Ontario Ministry of Economic Development and Innovation's through the Ontario Research Fund-Research Excellence Program. ; Cabrejas Peñuelas, J.; Roger Varea, S.; Calabuig Soler, D.; Fouad, YMM.; Gohary, RH.; Monserrat Del Río, JF.; Yanikomeroglu, H. (2016). Non-Coherent Open-Loop MIMO Communications Over Temporally-Correlated Channels. IEEE Access. 4:6161-6170. https://doi.org/10.1109/ACCESS.2016.2580680 ; S ; 6161 ; 6170 ; 4