We present a block minimum mean-squared error (MMSE) equalizer for orthogonal frequency-division multiplexing (OFDM) systems over time-varying multipath channels. The equalization algorithm exploits the band structure of frequency-domain channel matrix by means LDL/sup H/ factorization. complexity proposed is linear in number subcarriers and turns out to be smaller with respect serial MMSE characterized similar performance.

We introduce an analytical approach to evaluate the error probability of orthogonal frequency-division-multiplexing (OFDM) systems subject carrier frequency offset (CFO) in frequency-selective channels, characterized by Rayleigh or Rician fading. By properly exploiting Gaussian approximation intercarrier interference (ICI), we show that bit-error rate (BER) for uncoded OFDM system with quadrature amplitude modulation (QAM) can be expressed sum a few integrals, whose number depends on...

The Internet of Things (IoT) architecture is quickly becoming popular even outside its originating scenario home automation. This paper reports the design, implementation, and performance an IoT hardware software conceived for continuous monitoring livestock located in barns during grazing. We have adopted LoRa low power wide area network (LPWAN) technology to cover diverse environments, a suitable configuration web services perform data storage, analysis, visualization. Since LPWAN...

Recently, several approaches have been proposed for the equalization of orthogonal frequency-division multiplexing (OFDM) signals in challenging high-mobility scenarios. Among them, a minimum mean-squared error (MMSE) block linear equalizer (BLE), based on band LDL factorization, is particularly attractive its good tradeoff between performance and complexity. This paper extends this approach towards two directions. First, we boost BER BLE by designing receiver window specially tailored to...

We propose low-complexity block turbo equalizers for orthogonal frequency-division multiplexing (OFDM) systems in time-varying channels. The presented work is based on a soft minimum mean-squared error (MMSE) linear equalizer (BLE) that exploits the banded structure of frequency-domain channel matrix, as well receiver window enforces this structure. This equalization approach allows us to implement proposed designs with complexity only number subcarriers. Three are discussed: two biased MMSE...

This letter studies the symbol error probability (SEP) of quadrature-amplitude modulation (QAM) signals constructed from hexagonal lattice, known as QAM or triangular QAM. In particular, we propose a simple and accurate approximation for SEP in additive white Gaussian noise. Simulation results show that proposed is very all best-known constellations including QAM, both high low signal-to-noise ratio. addition, suitable estimation slow-fading channels, such Rayleigh fading channels.

This paper deals with the optimization of operational efficiency a fleet mobile robots, assigned delivery-like missions in complex outdoor scenarios. The due to limited onboard computation resources, need offload some computing tasks an edge/cloud server, requiring artificial intelligence and high loads. robots also reliable efficient radio communication network hosting servers. resource assignment aims at minimizing total latency delay caused by use links nodes. minimization is nonlinear...

We examine the small sample size performance of energy detector for spectrum sensing in AWGN. By making use cube-of-Gaussian approximation chi-squared random variables, we derive a novel, simple, and accurate analytical expression minimum number samples required to achieve desired probability detection false alarm. This way, can be calculated by with low complexity. also propose useful cooperative detection.

This paper considers a pilot-aided/data-aided Kalman channel estimator for OFDM in fast time-varying (TV) channels. Capitalizing on basis expansion model (BEM) and frequency-domain estimation philosophy, the system is designed to periodically switch between pilot-aided data-aided mode order reduce rate penalty introduced by training pilots. The suggested philosophy effective tracking changes with negligible mean squared error (MSE) penalty, if filter prediction capability coupled an...

Terrestrial or Handheld Digital Video Broadcasting (DVB-T/H) and Multimedia (T-DMB) are two popular broadcasting standards that enable digital television transmissions to handheld receivers. This paper presents a comprehensive performance comparison between the physical layers of DVB-T/H T-DMB when employed for mobile communications. By exploiting recently proposed fast simulation model, we assess BER coded OFDM systems in several realistic scenarios, taking into account Rayleigh Rice...

The minimum mean-squared error (MMSE) is one of the most popular criteria for Bayesian estimation. Conversely, signal-to-noise ratio (SNR) a typical performance criterion in communications, radar, and generally detection theory. In this paper we first formalize an SNR to design estimator, then prove that there exists equivalence between MMSE maximum-SNR estimators, any statistics. We also extend specific classes suboptimal which are expressed by basis expansion model (BEM). Then, exploiting...

This paper focuses on the performance of LoRa systems after channel decoding. First, we introduce a matrix model for coded transmission and reception signals. Second, theoretically evaluate probability bit error coherently noncoherently detected signals, in additive white Gaussian noise (AWGN), also assuming hard decoding physical layer Hamming code. Simulation results confirm correctness theoretical expressions. Third, analyze by simulation systems, with both soft decoding, multipath...

This paper presents a performance analysis of centralized spectrum sensing based on compressed measurements. We assume cooperative sensing, where unlicensed users individually perform and send their results to fusion center, which makes the final decision about presence or absence licensed user signal. Several cooperation schemes are considered, such as and-rule, or-rule, majority voting, soft equal-gain combining (EGC). The proposed provides simplified closed-form expressions that calculate...

This paper focuses on sensing-throughput tradeoffs for overlay cognitive radio networks. The goal is to maximize the opportunistic secondary user throughput, by limiting disturbance primary activity. Specifically, assuming that a Poisson birth-death process characterizes traffic, sensing-time bounds are imposed granting enough accuracy detection of activity, while optimum duration transmissions obtained maximizing analytical expressions average capacity. also clarifies some subtle...

This article proposes new approximations for the bit error probability of several LoRa-based schemes, such as phase-shift keying (PSK) LoRa, in-phase and quadrature (IQ) chirp spread spectrum (CSS), discrete rate (DCRK) CSS, CSS with index modulation (IM). We include a scheme that combines IQ, IM, denoted IQ (IQCIM). Our analysis, which assumes coherent detection in additive white Gaussian noise, compares schemes also terms spectral efficiency, computational complexity, peak-to-average power...

Digital terrestrial video broadcasting systems based on orthogonal frequency division multiplexing (OFDM), such as second generation of digital standard (DVB-T2), often include carriers reserved for peak-to-average power ratio (PAPR) reduction. This paper presents a low-complexity PAPR reduction method that inserts coded data onto subset carriers. Using differential binary phase shift keying (DBPSK) with repetition coding, the proposed generates time-domain peak-cancellation signal carries...

Modern wireless communication systems require high transmission rates, giving rise to frequency selectivity due multipath propagation. In addition, high-mobility terminals and scatterers induce Doppler shifts that introduce time selectivity. Therefore, advanced techniques are needed accurately model the time- frequency-selective (i.e., doubly selective) channels counteract related performance degradation. this paper, we develop new receivers for orthogonal frequency-division multiplexing...

Recently, a minimum mean-squared error (MMSE) block linear equalizer based on band LDL/sup H/ factorization has been proposed for equalization of orthogonal frequency-division multiplexing (OFDM) systems affected by Doppler spread. In this paper, we extend approach towards two directions. First, design an MMSE decision-feedback (DFE) the factorization. Both performance and complexity are analyzed. Second, enhance means receiver windows tailored to approach. Simulation results show that...

We present iterative turbo-like equalizers for multiple-input multiple-output (MIMO) orthogonal frequency-division multiplexing (OFDM) systems subject to frequency-selective channels with rapid time variation. The proposed are obtained from a Bayesian approach based on the unbiased minimum mean-squared error (MMSE) criterion, but also admit probabilistic data association (PDA) interpretation. Two discussed: basic version that makes use of symbol-level variance estimation, and an enhanced...

This paper analyzes the quality of service (QoS) scheduling algorithms for heterogeneous users in multi-user (MU) wireless systems that take advantage from a cross-layer design with both adaptive modulation and coding (AMC) automatic repeat request (ARQ). By developing general theoretical framework based on finite-state Markov chain, we analytically evaluate average delay, packet-loss rate (PLR) throughput algorithm channel condition, buffer occupancy, number retransmissions, belonging to...

We investigate multirate multicarrier code-division multiple-access (MC-CDMA) downlink systems with multicode transmission. Specifically, we design a new linear equalizer that outperforms the minimum mean-squared error (MMSE) per-carrier equalizer, without requiring spreading codes of interfering users. The complexity this is similar to MMSE per-user which however needs Simulation results validate effectiveness proposed especially when there are few