Universidade Federal do Ceará
Programa de Pós-Graduação em Engenharia de Teleinformática

1ª palestra: “Resource allocation with new filtered waveforms: performance evaluation”,
Dia: 04 dezembro 2017,
Horário: das 14 às 15 horas;

2ª palestra: “D2D communications: frequency, space and power optimization”,
Dia: 05 dezembro 2017,
Horário: das 10 às 11 horas.

Local das palestras – Sala de Seminários do Laboratório GTEL/DETI, Bloco 722, Departamento de Engenharia de Teleinformática, Centro de Tecnologia, Campus do Pici.

Abaixo encontram-se os resumos das palestras e a biografia da Profª Mylène Pischella.

Destacamos que a Profª Mylène Pischella estará a disposição dos interessados para discussão sobre suas apresentações e os temas de pesquisa de seu interesse de 01 a 08 de dezembro de 2017, no Laboratório GTEL/DETI.

Destacamos ainda que a visita da Profª Mylène Pischella está associada a sua missão de trabalho no contexto do Projeto de Pesquisa Nº 830/2015 do Programa CAPES-COFECUB, intitulado “Processamento de Sinais e de Informação com Aplicações em Telecomunicações e em Engenharia Biomédica – PSITEB”.

Presentations Dr Mylène Pischella, associate professor at CNAM Paris, France

A) First presentation: 12/04/17, 2h PM, Seminary room, GTEL Laboratory, Building 722, Campus do Pici

“Resource allocation with new filtered waveforms : performance evaluation”

The CEDRIC/LAETITIA team of CNAM has a long expertise on post-OFDM filtered waveforms, starting from FBMC (Filter Bank MultiCarrier) and the work of Professor Maurice Bellanger. The filtered waveforms proposed by our team are well-localized in the frequency domain, which is particularly interesting for asynchronous transmissions. If interfering signals are received asynchronously from the useful signal, then they generate Inter-Channel-Interference (ICI) on top of co-channel interference.
Waveforms that are not robust to asynchronicity due to large sidelobes, such as OFDM, generate ICI with large spread and amplitude. ICI must be taken into account in resource allocation in order to try to mitigate its effect. This presentation provides several scenario where ICI may occur, and resource allocation algorithms that take ICI into account.
The first studied scenario is an asynchronous ad hoc networks with downlink transmission for
infrastructure-less networks (after a disaster like tsunami or hearthquake, for instance). In this case, we provide cluster-based subcarrier allocation followed by iterative power allocation, with the objective to maximize the network sum rate. In the second scenario, we consider uplink underlay Device-to-Device (D2D) communications coexisting with a cellular network. Subcarrier allocation is performed with graph coloring for D2D pairs, and a distributed power allocation algorithm aiming at maximizing the weighted sum rate of D2D pairs, subject to a maximum interference constraint at the BS is then proposed. This algorithm can be used to maximize the spectral efficiency, but also to perform cross-layer PHY-MAC optimization, if the weight of each D2D pair is proportional to the buffer size of its transmitter. Both cases are tested with simulations and show that using filtered waveforms such as FBMC is far more efficient than using OFDM in this asynchronous context. Finally, the D2D power allocation problem is studied when we impose a per-Resource Block (RB) power allocation constraint, which is more realistic than per-subcarrier allocation. A new formulation of the optimization problem, taking this constraint into account, is derived. Simulation results again show the superiority of FBMC over OFDM.

B) Second presentation: 12/05/17, 10h AM, Seminary room, GTEL Laboratory, Building 722, Campus do Pici

“D2D communications : frequency, space and power optimization”

Device-to-device (D2D) communications can be established between two nearby mobile users that are directly exchanging data. Such direct communication has many advantages since it decreases latency, increases the data rate, and decreases power consumption due to low propagation loss. Moreover, the spectrum can be shared by several D2D pairs if they are far enough to assume that their mutual interference is negligible. However, efficient spectrum sharing and multiplexing requires relevant resource allocation in order to achieve the expected spectral efficiency gains. Two types of D2D communications can be distinguished : first, overlay communications, where the D2D pairs use a separate bandwidth from cellular users. Second, underlay communications, where both D2D and cellular users share the same bandwidth, but cellular users have a higher priority and consequently, the interference generated by D2D transmitters at the Base Station (BS) should be lower than a given threshold.
This presentation focuses on both types of communications. In the overlay case, two different
optimization problems are studied : first, the maximum multiplexing problem of D2D pairs when
interferences are fully asynchronous and therefore generate Inter-Channel-Interference (ICI), whose spread and amplitude depends on the multi-carrier modulation. Second, the MIMO antenna selection problem with the objective to maximize the sum data rate of all D2D pairs. In the underlay case, resource allocation for D2D pair must also take into account the received interference from cellular users and the interference generates at the BS. We first study the power allocation problem for D2D pairs, whose objective is to maximize their weighted sum data rate, subject to an interference threshold constraint at the BS. In this scenario, we assume ICI due to asynchronous transmissions and take into account the fact that power allocation is performed per RB, even though ICI is applied per subcarrier. This algorithm is derived for SISO. In a last section, we extend it to SIMO, when the BS is equipped with several antennas. Then, RB allocation is performed with the objective to serve one cellcenter and several cell-edge D2D pairs per RB. The selected cell-center D2D pair is semi-orthogonal to the selected cellular user in each RB, thus leading to low interference at the BS, even if high transmit power values are used.
These four contributions show that D2D communications can be optimized with various variables in frequency, space and power domains. They also show that great data rates improvements can be achieved with efficient multiplexing.

C) Short biography:

Dr Mylene Pischella (mylene.pischella@cnam.fr) has been an associate professor in telecommunications at CNAM since 2010. She received a Master’s degree in engineering in 2002 and a Ph.D. in communications and electronics in 2009, both from TELECOM ParisTech. From 2002 to 2009, she was a research engineer at Orange Labs, where she specialized in the optimization of cellular networks and contributed to several European collaborative projects. In 2009–2010, she was an assistant professor at ISEP, Paris, France. She is an author of more than 60 peer-reviewed papers, three books, one book chapter, and seven patents. Her research interests are resource allocation in wireless networks, including heterogeneous networks, device-to-device communications, multi-carrrier modulation, and cognitive, cooperative, and relaying networks.