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In this paper, we have proposed a novel passive ultra high frequency (UHF) radio frequency identification (RFID) metal tag antenna mountable on the metallic surface to resonate at 930 MHz. The techniques with double slits for impedance matching and reading distance enhancement is used to obtain a good performance. All simulations are carried out by Ansoft HFSS software and Intermec read verifies the...
We compare three clipping techniques for reducing the PAPR of an UFMC signal over an AWGN channel. First, the techniques are analyzed probabilistically showing that deep clipping reduces the most, but it also has the worst performance. Then, the percentile levels of deep factor and level clipping are optimized, achieving similar performance that common techniques.
In this paper, we address the problem of estimating channel impulse response (CIR) and carrier frequency offset (CFO) in OFDM systems utilizing the method of maximum likelihood. When the CFO is small, Moose's technique for CFO estimation is accurate and numerically efficient. However, if the CFO is high, there are no straightforward solutions for its estimation. We show that the log-likelihood function...
Methods based on order statistics are often used in finance, quality control, data and signal processing, especially when signals of interest are immersed in impulsive noise. These allow to include rank information by increasing the dimension of the problem. In large dimension problems, we are usually required to know only the second order statistics. In this article we use a rank-one quadratic measurement...
The design of blind rendezvous strategies for dynamic spectrum access in multi-users, multi-hop networks is a challenging task. In this paper, a two radios synchronization strategy that minimizes the time to rendezvous in multi-users networks is analyze. In fact, it has been recently demonstrated that this synchronization strategy provides optimum results in terms of maximum time to rendezvous (MTTR)...
Wireless applications require the use of Power Amplifiers for signal transmission. Those are generally nonlinear devices, and there is a trade-off between efficiency and the signal distortion level, which degrades performance. Besides that, transmission waveforms suffer from spectral regrowth when non-linearities are present. Moreover, some power amplifiers also carry memory effects, which further...
In this work, we present an acoustic modem system that transmits data using multicarrier modulation through the air interface. The choice for this type of modulation over single carrier modulation arises from the need for an efficient use of the limited bandwidth, the minimization of multipath effects as frequency fading. The system transmits data using sound waves resting on the output and input...
Minimum mean square error (MMSE) linear detector has been considered as one of the potential detection algorithm for uplink multi-user massive MIMO systems, because it can achieve the near-optimal bit error rate (BER) performance. However, it involves matrix inversion with high complexity. Thus, the conventional Gauss-Seidel (GS) method has been applied for obtain a low-complexity MMSE detector without...
In this paper, self-interference (SI) cancellation algorithm based on Space Projection Algorithm (SPA) is proposed for Full-Duplex (FD) Multiple-Input Multiple-Output (MIMO) relays in an indoor wireless communication system. The simultaneous transmission and reception of the same radio signal imply a SI around the relay transceiver. The principal challenge of implementing the FD-MIMO relay is to this...
In massive multiple-input multiple-output (MIMO) systems, with the increase of the number of received antennas at base station (BS), the linear detectors, as minimum mean-square error (MMSE), are able to achieve the near-optimal performance. However, these detectors involve matrix inversion with high complexity. Thus, in order to reduce the complexity, Neumann Series (NS) expansion has been proposed...
The lack of technical equipment is one of the hurdles in facing challenges in engineering education and basic research for universities in developing countries. In this paper we present a low-cost laboratory mostly based on commercial off-the-shelf wifi routers. A basic workbench is made out of three second hand wireless routers. Our local market provided plenty of used D-Link DIR-300. Total cost...
There has been a high concern regarding the energy saving on mobile devices recently, for mobile devices have been performing increasingly complex tasks over time. The computation offloading is one of the most popular techniques used by developers as an effective way of saving energy on mobile devices, which consists on executing complex tasks in external servers with different purposes including...
In this paper we propose an SDN-based control plane for the University of Costa Rica. Our campus network faces heavy congestion problems and fails at providing adequate quality of service (QoS). Therefore, we describe a solution that leverages priority-traffic routing to ensure that important services (such as live video streaming) are not as heavily affected by congestion. To this end, we first survey...
In this paper, we consider the deployment of multiple antennas as a way to exploit spatial diversity in the uplink of multiple access systems that adopt low-density spreading (LDS) with orthogonal frequency-division multiplexing (OFDM). An overloaded LDS-OFDM system is assumed, i.e., the number of users served is assumed greater than the number of resources. A basic model is developed and from it...
A WBANs (Wireless Body Area Networks) number dimensioning technique for cluster-type network structure is proposed in this paper. The WBANs, in this structure, are placed, together with the sink nodes, at the ends of the network. An access scheme is provided so that the sink nodes, which temporarily store the data packets of the WBANs, transmit these packets to the collector nodes. The collector nodes...
This paper demonstrates an innovative variable fractional rate Digital Down Converter(DDC) architecture for satellite communication where the carrier frequency and output sample rate can be changed dynamically at run time. The proposed algorithm is highly modular and generic so that the DDC can decimate by any fractional ratio i.e. the ADC sampling rate may be any integer or non-integer multiple of...
It is well-know that carrier frequency offset in the subcarriers of orthogonal frequency division multiplexing (OFDM) leads to intercarrier interference (ICI); therefore, system degradation occurs. Nevertheless, this issue may effectively be mitigated via the pulse shaping filter method. In this manuscript, we present the improved double jump linear combination (IDJLC) function. With the goal of minimizing...
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