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New robust iterative minimum mean squared error-based interference alignment al...
Teodoro, Sara; Silva, Adão; Castanheira, Daniel; Dinis, Rui; Gameiro, AtílioInterference alignment (IA) is a promising technique for multiple input multiple output interference channels based systems, achieving the theoretical bound on degrees of freedom. However, these gains are reduced in the presence of imperfect channel state informa- tion (CSI), because of quantisation or channel estimation errors. In this Letter, the authors propose a new robust iterative IA minimum mean squared ...
Low-bit rate feedback strategies for iterative IA-precoded MIMO-OFDM-based systems
Teodoro, Sara; Silva, Adão; Dinis, Rui; Gameiro, AtílioInterference alignment (IA) is a promising technique that allows high-capacity gains in interference channels, but which requires the knowledge of the channel state information (CSI) for all the system links. We design low-complexity and low-bit rate feedback strategies where a quantized version of some CSI parameters is fed back from the user terminal (UT) to the base station (BS), which shares it with the oth...
On Coordinated Multi-Point Transmission for Cellular Environments
Silva, Mário Marques da; Correia, Américo; Dinis, Rui; Montezuma, PauloCurrent and emergent services are demanding higher data rates, improved spectral e±ciency and increased network capacity. To face these new requirements, it is important to ¯nd schemes able to reduce the e®ects of fading and to exploit new types of diversity. Coordinated Multi-Point transmission (CoMP) comprises the coordinated transmission of signals from adjacent base stations (BS), and the corresponding rece...
Multiple Input Multiple Output System with Multi User Support Based on Directiv...
Carvalho, Paulo; Silva, Mário Marques da; Dinis, RuiLow interference and privacy are crucial requirements for system reliability and security. Present and further mobile communication systems must support multiple users achieving at same time low interference levels. Several solutions can be adopted to reduce interference between users, such as spreading codes or beam forming. For very high bit rates ¯rst solution must be discarded. On the other hand, in environ...
A novel distributed power allocation scheme for coordinated multicell systems
Silva, Adão; Holakouei, Reza; Castanheira, Daniel; Gameiro, Atílio; Dinis, RuiCoordination between base stations (BSs) is a promising solution for cellular wireless systems to mitigate intercell interference, improving system fairness, and increasing capacity in the years to come. The aim of this manuscript is to propose a new distributed power allocation scheme for the downlink of distributed precoded multicell MISO-OFDM systems. By treating the multicell system as a superposition of si...
Receptor no Domínio da Frequência para Modulações SC-FDE com STBC
Silva, Mário Marques da; Dinis, Rui; Correia, AméricoSão apresentados métodos para suportar transmissões baseadas na técnica de Transmissão com Portadora Única, com Igualação no Domínio da Frequência (SC-FDE), utilizando diversidade de transmissão, com codificação no espaço e no tempo. O objectivo do sistema proposto consiste em permitir a difusão de informação a partir de terminais de comunicações móveis, conseguindo-se uma melhor eficiência de desempenho e/ou d...
Performance evaluation of IB-DFE-based strategies for SC-FDMA systems
Silva, Adão; Assunção, José; Dinis, Rui; Gameiro, AtílioThe aim of this paper is to propose and evaluate multi-user iterative block decision feedback equalization (IB-DFE) schemes for the uplink of single-carrier frequency-division multiple access (SC-FDMA)-based systems. It is assumed that a set of single antenna users share the same physical channel to transmit its own information to the base station, which is equipped with an antenna array. Two space-frequency mu...
Uplink of base station cooperation systems with SC-FDE modulations and IB-DFE r...
Ribeiro, Filipe; Cercas, Francisco; Dinis, Rui; Silva, AdãoThis paper considers the uplink transmission in BS (Base Station) cooperation schemes where users in adjacent cells share the same physical channel and the signals received by each BS are sent to a CPU (Central Processing Unit) that combines the different received signals associated to a given user and/or performs the user separation. The signals are modulated through SC (Single-Carrier) schemes combined with F...
Transmission Techniques for 4G Systems
Silva, Mário Marques da; Correia, Américo; Dinis, Rui; Souto, Nuno; Silva, João CarlosFourth Generation wireless communication systems (4G) aim to allow peak data rates in the range of 1 Gbps for nomadic access and 100 Mbps for vehicular mobility. 4G aim to support current and emergent multimedia services, such as mobile TV, social networks and gaming, high definition television and video teleconference, multimedia messaging service, using the all over IP concept and with improved quality of ser...
A spectrally efficient transmission scheme for signals with large bandwidth
Silva, Paulo; Dinis, RuiIn this paper we consider single-carrier with frequency-domain equalization (SC-FDE) schemes where the transmission bandwidth is above the symbol rate. To allow high spectral efficiencies, several channels share the same bandwidth. Since the co-channel interference (CCI) levels can be very high, we propose iterative FDE receivers where we jointly detect all users sharing the same channel. Our performance result...
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