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We are witnessing a revolution in wireless technology where Light Fidelity (LiFi) emerges as one potential candidate. In this paper we present a LiFi prototype that allows us to verify the feasibility of deploying this technology. The prototype is based on two Spartan 6 FPGAs and uses a Light Emitting Diode (LED) to transport the information through amplitude changes of the light. The receiver uses...
Recently, massive MIMO systems have attracted a great attention due to its spectral efficiency and increase in transmission capacity required by next generation of wireless systems. However, this technology presents some disadvantages like the high cost, physical size and complexity of the hardware in the RF chain (eg. individual radio frequency (RF) chains are required per antenna element). Hence,...
In this paper, a functional LiFi real-time testbed implemented on FPGAs is presented. The setup evaluates the performance of our design in a downlink scenario where the transmitter is embedded on the streetlights and a mobile phone's camera is used as receiver, therefore achieving the goal of lighting and communicating simultaneously. To validate the design, simulations of the whole system are performed...
An experimental evaluation of Blind Interference Alignment (BIA) over a hardware platform is presented in this work. In contrast to other transmission techniques such as Linear Zero Forcing Beamforming (LZFB) or Interference Alignment (IA), BIA achieves a growth in Degrees of Freedom (DoF) without channel state information at the transmitter (CSIT). A real implementation based on Orthogonal Frequency...
Optimum scheduling is a key objective in many communications systems where different users have to share a common resource. Typically, centralized implementations are capable of guaranteeing certain fairness. In our approach, we follow a different path modeling the scheduling process as a dynamic infinite horizon discrete-time game. This formulation allows us to include any kind of dynamics and distributed...
Modern communications systems use efficient encoding schemes, multiple-input multiple-output (MIMO) and high-order QAM constellations for maximizing spectral efficiency. However, as the dimensions of the system grow, the design of efficient and low-complexity MIMO receivers possesses technical challenges. Symbol detection can no longer rely on conventional approaches for posterior probability computation...
An interference aware precoding scheme based on limited channel state information at the transmitter (CSIT) is considered for its use in the downlink of a cellular system. The transmitter precoder used is based on an MMSE-ZF criterion in order to maximize the user rate while the interference to other users is reduced. The proposed scheme also exploits the network topology, so that each BS can categorize...
This paper addresses an uplink power control dynamic game where we assume that each user battery represents the system state that changes with time following a discrete-time version of a differential game. To overcome the complexity of the analysis of a dynamic game approach we focus on the concept of Dynamic Potential Games showing that the game can be solved as an equivalent Multivariate Optimum...
In this work an interference-aware precoder design is proposed for a downlink wireless cellular system. Each base-station designs a precoder with a joint MMSE-ZF criteria for the user information and the interference to other cells. In a realistic power constraint scenario, where each base-station has a limitation on the maximum power available power to be transmitted, the precoder filter can be analytically...
This paper contributes with a unified formulation that merges previous analysis on the prediction of the performance (value function) of certain sequence of actions (policy) when an agent operates a Markov decision process with large state-space. When the states are represented by features and the value function is linearly approximated, our analysis reveals a new relationship between two common cost...
Filterbank based multicarrier modulations are well known to perform poorly in frequency selective channels when single tap carrier-by-carrier equalization is used. This degradation is cased by the inherent distortion in terms of inter-symbol and inter-carrier interference at the receiving side, which cannot be compensated via single-tap equalization. We provide here an asymptotic characterization...
This paper addresses the problem of resource allocation in a multiple access channel where several mobile terminals (MT's) are transmitting simultaneously to a single receiving base station, all of them with multiple antennas and exploiting beamforming. A multi-carrier modulation is assumed, either orthogonal frequency division multiplexing (OFDM) or filter bank multi-carrier (FBMC). The main advantage...
In a Coordinated Base Station Transmission scenario for the downlink, we propose a precoding scheme based on a MMSE criterion to manage the inter-user interference. In order to allocate the transmitted power to each user's signal, we set up an iterative procedure based on a modified waterfilling distribution, which approaches the optimal performance with a viable complexity with respect to the numerical...
A relay station (RS)-based cellular system deployment is considered, where multiple base stations (BS) cooperate in the BS-RS in-band transmission for the downlink. With the joint optimization of the resources allocated to the wireless backhaul and to the RS-MS access, it is possible to exploit the benefits of networked-MIMO along with combating the pathloss and shadowing effects, and thus obtain...
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