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Protocol for Extreme Low Latency M2M Communication Networks
Publication . Shamsudin, Rahim Karim; Bernardo, Luís
As technology evolves, more Machine to Machine (M2M) deployments and mission critical
services are expected to grow massively, generating new and diverse forms of data
traffic, posing unprecedented challenges in requirements such as delay, reliability, energy
consumption and scalability. This new paradigm vindicates a new set of stringent requirements
that the current mobile networks do not support. A new generation of mobile
networks is needed to attend to this innovative services and requirements - the The fifth
generation of mobile networks (5G) networks. Specifically, achieving ultra-reliable low
latency communication for machine to machine networks represents a major challenge,
that requires a new approach to the design of the Physical (PHY) and Medium Access
Control (MAC) layer to provide these novel services and handle the new heterogeneous
environment in 5G. The current LTE Advanced (LTE-A) radio access network orthogonality
and synchronization requirements are obstacles for this new 5G architecture, since
devices in M2M generate bursty and sporadic traffic, and therefore should not be obliged
to follow the synchronization of the LTE-A PHY layer. A non-orthogonal access scheme
is required, that enables asynchronous access and that does not degrade the spectrum.
This dissertation addresses the requirements of URLLC M2M traffic at the MAC layer.
It proposes an extension of the M2M H-NDMA protocol for a multi base station scenario
and a power control scheme to adapt the protocol to the requirements of URLLC. The
system and power control schemes performance and the introduction of more base stations
are analyzed in a system level simulator developed in MATLAB, which implements
the MAC protocol and applies the power control algorithm.
Results showed that with the increase in the number of base stations, delay can be
significantly reduced and the protocol supports more devices without compromising
delay or reliability bounds for Ultra-Reliable and Low Latency Communication (URLLC),
while also increasing the throughput. The extension of the protocol will enable the study
of different power control algorithms for more complex scenarios and access schemes that
combine asynchronous and synchronous access.
Recolha de Energia sem Fios em Redes de Rádio Cognitivo
Publication . Oliveira, Daniela Vanessa Joaquim; Oliveira, Rodolfo
A crescente utilização das redes sem fios requer que as redes futuras consigam suportar maior quantidade de tráfego e que sejam mais eficientes em termos energéticos. Este facto levanta diversos desafios, dois dos quais abordados nesta dissertação: a escassez de espetro eletromagnético, e a diversificação de fontes energéticas.
A introdução da técnica de recolha de energia eletromagnética em nós não licenciados
de uma rede de rádio cognitivo permite que os nós utilizem uma fonte de energia
não convencional. O principal desafio da caracterização deste tipo de redes está relacionado com o impacto da técnica de recolha de energia eletromagnética no débito da rede.
Para além do tempo despendido na análise da disponibilidade do espetro para efetuar
transmissões, é também necessário acumular energia a partir das ondas eletromagnéticas para efetuar a transmissão, implicando dois períodos de espera temporal que poderão ser significativos. Logo, é necessário um balanceamento entre o tempo despendido para carregar a bateria e para a análise da disponibilidade do espetro, de forma a minimizar o tempo de transmissão de um pacote, maximizando o débito de um nó.
Nesta dissertação são propostos três modelos que permitem caracterizar o comportamento de uma rede de rádio cognitivo com recolha de energia. O primeiro modelo caracteriza a potência recebida por um nó a partir de múltiplos transmissores. Este modelo permite caracterizar a energia acumulada durante um determinado intervalo de tempo, sendo utilizada pelo segundo modelo para determinar a probabilidade de um nó já ter acumulado energia suficiente para transmitir. Por fim, o terceiro modelo avalia o débito da rede de rádio cognitiva com recolha de energia. Considerando o processo de análise de espetro realizado pelos nós não licenciados, bem como o tempo necessário para acumular energia suficiente para transmitir. Através do terceiro modelo, é possível analisar quais os fatores que têm mais impacto no débito da rede. O trabalho proposto constitui uma ferramenta de análise que poderá alicerçar mecanismos futuros de otimização da rede.
Massive MIMO downlink based on single carrier frequency domain processing
Publication . Mokhtari, Zahra; Sabbaghian, Maryam; Dinis, Rui; DEE2010-A1 Telecomunicações; DEE - Departamento de Engenharia Electrotécnica e de Computadores; CTS - Centro de Tecnologia e Sistemas; UNINOVA-Instituto de Desenvolvimento de Novas Tecnologias; Institute of Electrical and Electronics Engineers (IEEE)
In this paper, we investigate the suitability of single carrier frequency domain processing (SC-FDP) as the downlink transmission scheme in a massive multiple-input multiple-output (MIMO) system. By deriving the sum-rate of the SC-FDP massive MIMO system theoretically, we show that this method obtains a sum-rate similar to that of orthogonal frequency division multiplexing (OFDM) massive MIMO. We also derive the theoretical sum-rate of both SC-FDP and OFDM in a non-synchronized massive MIMO scenario and show that the rate of the former is significantly larger than that of the latter. Moreover, we theoretically analyze the sum-rate of both systems in the presence of power amplifier non-linearity. All the sum-rates are derived for both zero forcing and matched filter precoding schemes. The results show that the effect of power amplifier non-linearity on the sum-rate of both systems is similar when the number of users is large. We also compare SC-FDP with OFDM from the peak to average power ratio (PAPR) and complexity viewpoints. Although the PAPR of SC-FDP signals is lower than that of OFDM signals, for MIMO systems, the difference between their PAPR decreases as we increase the number of users. Thus, both techniques can have similar PAPR in massive MIMO systems. The overall complexity of SC-FDP and OFDM is similar. Due to the mentioned facts, SC-FDP can be considered as a promising transmission scheme for the downlink of the massive MIMO systems in the presence of carrier frequency offset and power amplifier non-linearities.
Receiver Design to Employ Simultaneous Wireless Information and Power Transmission with Joint CFO and Channel Estimation
Publication . Rajaram, Akashkumar; Dinis, Rui; Jayakody, Dushantha Nalin K.; Kumar, Neeraj; DEE2010-A1 Telecomunicações; DEE - Departamento de Engenharia Electrotécnica e de Computadores; CTS - Centro de Tecnologia e Sistemas; UNINOVA-Instituto de Desenvolvimento de Novas Tecnologias; Institute of Electrical and Electronics Engineers (IEEE)
Radio-frequency energy harvesting (EH) is one of the enabling technologies for the next-generation wireless communication systems. EH techniques are specifically used to improve the energy efficiency of the system. Recently, the simultaneous wireless information and power transmission (SWIPT) protocol is adapted for EH. In this paper, we design a new receiver for joint carrier frequency offset (CFO) and channel estimation on single-carrier modulations with frequency-domain equalization along with SWIPT implementation for EH by using the pilot signal. The pilot signal is a highly energized signal, which is superimposed with the information signal. The superimposed signal is used not only to transmit power for EH purposes but also to estimate the CFO and channel conditions. The receiver is designed to accommodate the strong interference levels in the channel estimation and data detection. The proposed scheme offers a flexible design method and efficient resource utilization. We validate our analytical results using simulations.
Power amplification efficient transmitter structures for massive MIMO with SC-FDE schemes: A promising combination for 5G systems?
Publication . Montezuma, Paulo; Ferreira, Afonso; Dinis, Rui; Beko, Marko; DEE2010-A1 Telecomunicações; CTS - Centro de Tecnologia e Sistemas; DEE - Departamento de Engenharia Electrotécnica e de Computadores; UNINOVA-Instituto de Desenvolvimento de Novas Tecnologias; Czech Technical University in Prague
It is well-known that massive multiple-input multiple-output (MIMO) systems have high potential for future wireless broadband systems. Requirements such as high spectral and power efficiency are also crucial in 5G. Based on a multi-amplifier structure it is possible to define a double layered structure where each amplification branch is connected to an antenna array to achieve both constellation and power directivies, assuring at same time similar performances to systems using transmitters with 2-dimensional antenna arrays. Thus, a different path can be followed to improve energy efficiency of power amplification where the usage of parallel amplification branches is combined with big arrays of antennas and multi-stream communication systems. These systems can be combined with single-carrier with frequency domain equalization (SC-FDE) schemes to improve the power efficiency in uplink due to the low envelope fluctuations.
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Entidade financiadora
Fundação para a Ciência e a Tecnologia
Programa de financiamento
5876
Número da atribuição
UID/EEA/50008/2013