In this paper, a novel and efficient scheme for jamming the Universal Mobile Telecommunications System (UMTS) signal without the assistance from the base station or operator is proposed and ...evaluated. The scheme is based on new orthogonal multi-sequences developed in this paper. These sequences are specially designed to interfere all the Orthogonal Variable Spread Factor (OVSF) codes that are used in the UMTS transmission and thus, any signal spread by these multi-sequences will interfere all the transmitted data channels at the same time. A power gain of about 7 dB is obtained with respect to the traditional jamming method based on high power wide-band noise injection can be obtained when no channel is used and 10.4 dB in a more realistic scenario with multipath Rayleigh channel.
Intelligent transportation systems (ITS) are usually approached by exhaustive measuring and complex signal processing including medium-high cost hardware deployment. In this paper, a novel design of ...a wireless sensor network system using magnetometers and microphones for the detection and avoidance of traffic jams is described and analyzed. The system, which can also be used for traffic monitoring and surveillance, is simple, energy efficient, and accurate which allows to be implemented with a reduced hardware cost. In order to reduce the maintenance tasks, mini solar panels would also be installed for powering up the motes in the near future.
In this paper, a blind robust timing synchronization method, based on invariance properties and cyclostationarity, for multicarrier systems such as Orthogonal Frequency Division Multiplexing (OFDM) ...is proposed and evaluated. Its results outperform the state-of-the-art for blind methods, specially in hard wireless channels where our proposal is highly superior. It even surpasses the performance of most of non-blind (pilot-aided) methods, while at the same time, it gets the advantages of energy and bandwidth saving of blind proposals. Moreover, since this technique does not require the use of pilots, it can be easily applied to either packet-based or broadcasting systems.
In this paper, several algorithms for compressing the feedback of channel quality information are presented and analyzed. These algorithms are developed for a proposed adaptive modulation scheme for ...future multi-carrier 4G mobile systems. These strategies compress the feedback data and, used together with opportunistic scheduling, drastically reduce the feedback data rate. Thus the adaptive modulation schemes become more suitable and efficient to be implemented in future mobile systems, increasing data throughput and overall system performance.
The design, implementation, and test of a real-time flexible
(Multiple Input Multiple Output-Orthogonal Frequency Division Multiplexing) MIMO-OFDM IEEE 802.16 prototype are presented. For the design, ...a channel measurement campaign on the 3.5 GHz band has been carried out, focusing on outdoor-indoor scenarios. The analysis of measured channels showed that higher capacity can be achieved in case of obstructed scenarios and that (Channel Distribution Information at the Transmitter) CDIT capacity is close to (Channel State Information at the Transmitter) CSIT with much lower complexity and requirements in terms of channel estimation and feedback. The baseband prototype used an (Field Programmable Gate Array) FPGA where enhanced signal processing algorithms are implemented in order to improve system performance. We have shown that for MIMO-OFDM systems, extra signal processing such as enhanced joint channel and frequency offset estimation is needed to obtain a good performance and approach in practice the theoretical capacity improvements.
Fifth-generation (5G) networks have been deployed alongside fourth-generation networks in high-traffic areas. The most recent 5G mobile communication access technology includes mmWave and sub-6 GHz ...C-bands. However, 5G signals possibly interfere with existing radio systems because they are using adjacent and co-channel frequencies. Therefore, the minimisation of the interference of 5G with other signals already deployed for other services, such as fixed-satellite service Earth stations (FSS-Ess), is urgently needed. The novelty of this paper is that it addresses issues using measurements from 5G base stations (5G-BS) and FSS-ES, simulation analysis, and prediction modelling based on artificial neural network learning models (ANN-LMs). The ANN-LMs models are used to classify interference events into two classes, namely, adjacent and co-channel interference. In particular, ANN-LMs incorporating the radial basis function neural network (RBFNN) and general regression neural network (GRNN) are implemented. Numerical results considering real measurements carried out in Malaysia show that RBFNN evidences better accuracy with respect to its GRNN counterpart. The outcomes of this work can be exploited in the future as a baseline for coexistence and/or mitigation techniques.
This work deals with the problem of radio resource allocation in a point-to-point multiple-input multiple-output (MIMO) communications system with feedback of channel state information. A total pool ...of radio resources (power and transmission time) is allocated among training, feedback, and data transmission phases in order to maximize system performance in terms of throughput. The energy consumption associated to the base band signal processing and decoding is also evaluated. This resource allocation problem is studied analytically in a two-way time division duplex (TDD) communications scenario with time correlated channels, where the effect of feedback errors and feedback delay is also taken into account.
Visible light communication (VLC) is a growing technology that can complement radio frequency to fulfill the increasing demand for wireless data services. VLC exploits the already deployed ...illumination infrastructure based on light-emitting diodes to communicate data. While mirrors have been traditionally used for interior decoration, among other applications, to what extent can they be deployed to improve VLC performance? In this paper, we propose optimizing the placement of mirrors to minimize the outage area, a common problem in VLC when line-of-sight link blockage occurs. We compare this optimal performance with a single-rectangular mirror array, a common mirror shape that is found indoors. We also study the most helpful mirror placement under different conditions. We show that our outage minimization algorithm, MinOut, easily provides threefold outage reductions. Besides, we demonstrate that a single-rectangular mirror array with orientation mobility can provide similar or even better performance than an optimal distributed mirror placement without mobility.
Visible light communication (VLC) is a technology that complements radio frequency (RF) to fulfill the ever-increasing demand for wireless data traffic. The ubiquity of light-emitting diodes (LEDs), ...exploited as transmitters, increases the VLC market penetration and positions it as one of the most promising technologies to alleviate the spectrum scarcity of RF. However, VLC deployment is hindered by blockage causing connectivity outages in the presence of obstacles. Recently, optical reconfigurable intelligent surfaces (ORISs) have been considered to mitigate this problem. While prior works exploit ORISs for data or secrecy rate maximization, this paper studies the optimal placement of mirrors and ORISs, and the LED power allocation, for jointly minimizing the outage probability while keeping the lighting standards. We describe an optimal outage minimization framework and present solvable heuristics. We provide extensive numerical results and show that the use of ORISs may reduce the outage probability by up to 67% with respect to a no-mirror scenario and provide a gain of hundreds of kbit/J in optical energy efficiency with respect to the presented benchmark.
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