1,721,068 research outputs found
On the LoRa Chirp Spread Spectrum Modulation: Signal Properties and Their Impact on Transmitter and Receiver Architectures
Full text linkThe LoRa modulation scheme is arousing a growing interest in the Internet of Things community as it is adopted by the emerging LoRaWAN technology. In this paper, we firstly analyse the baseband processing for the generation of LoRa signals at the transmitter side, providing a simple algorithm that leverages digital signal processing techniques to reduce the modulator complexity. Secondly, we analytically investigate the signal demodulation technique. Quite surprisingly, we found that its effectiveness depends on the particular choice of the sampling frequency at the receiver side, which purposely does not meet the sampling theorem requirement. Finally, we consider the actual architecture of digital receivers investigating the trade-off between the selectivity of receive digital filters, which impacts on the required computational effort and power consumption, and the receiver performance
Bluetooth and IEEE 802.11b coexistence: Analytical performance evaluation in fading channels
No full textIn this paper, the issue of Bluetooth and IEEE802.11b coexistence in a heterogeneous environments is addressed by means of an integrated analytical approach. The methodology proposed carefully takes both physical (i.e., thermal noise, propagation, interference, modulation formats, and coding techniques) and medium access control (frequency hopping, packet structures, traffic loads) aspects into account. This model can be easily implemented when developing network simulators, thus avoiding the need of extensive bit level Monte Carlo simulations at the physical level. The mean packet error probability is evaluated as a function of the relative distance between the two systems for different conditions (e.g., propagation, packet type, traffic loading, etc). In particular, how the presence or absence of line-of-sight propagation significantly affects the coexistence distance is emphasized. Furthermore, for a fixed quality-of-service level we derive the coexistence domain of the two considered systems in terms of relative distance
Exploiting the Agent's Memory in Asymptotic and Finite-time Consensus over Multi-agent Networks
Full text linkThis paper proposes two average consensus algorithms exploiting the memory of agents. The performance of the proposed as well as of several state-of-the-art consensus algorithms is evaluated considering different communication ranges, and evaluating the impact of transmission errors. To compare asymptotic and finite-time average consensus schemes, the ε-convergence time is adopted for a fair comparison. A discussion about memory requirements, transmission overhead, a priori information on network topology, and robustness to errors is provided
Performance Evaluation of a Bluetooth-Based WLAN Adopting a Polling Protocol under Realistic Channel Conditions
No full textEven if Bluetooth has not been specifically designated for WLANs (Wireless Local Area Networks) and the interconnection of computers, the possibility of establishing low-cost wireless connections makes this technology attractive for this kind of context also. In this paper we assess, by means of a simulative approach that takes the complete physical and MAC level aspects into account, the performance of a Bluetooth-based WLAN adopting a roll-call polling protocol under realistic channel conditions, that is, in the presence of the typical impairments of indoor wireless communications (fading, etc); moreover, we propose an analytical formulation to derive the maximum throughput offered by a Bluetooth link and we suggest a call admission control technique based on the previous analytical considerations
Characterization of Orthogonal Chirp Division Multiplexing and Performance Evaluation at THz Frequencies in the Presence of Phase Noise
Full text linkDue to its superior performance, Orthogonal Chirp Division Multiplexing (OCDM) has recently gained attention as a potential replacement for Orthogonal Frequency Division Multiplexing (OFDM) in beyond-5G systems. In this paper, we provide an analytical characterization of OCDM signals, elucidating the theoretical principles that enable their numerical generation through the Inverse Discrete Fresnel Transform (IDFnT), despite the presence of severe frequency-domain aliasing that substantially distorts the signal at the transmitter output. Furthermore, in light of the proposed utilization of the THz band in beyond-5G systems, we investigate the performance of OCDM in this frequency range in the presence of thermal, molecular, and phase noise. To model the latter, which is expected to be a significant challenge at THz frequencies, we take as a reference an actual Phase Locked Loop (PLL) oscillator operating at 237.7 GHz. The numerical results reveal the achievable performance of OCDM as a function of several key factors, including the modulation order, the bandwidth, the number of chirps constituting the signal, the oscillator parameters, the channel model, and the use of techniques aimed at mitigating the impact of phase noise. The findings are compared with those of OFDM, which is regarded as a benchmark due to its adoption in 4G and 5G systems, and demonstrate the superior performance of OCDM also in the presence of significant phase noise
Low-Power Wide-Area Networks:comparison of LoRaWAN and NB-IoT performance
Full text linkAbstract
Low Power Wide Area Networks (LPWANs) have become an important enabler for the Internet of Things (IoT) connectivity. Application domains like smart cities, smart agriculture, intelligent logistics and transportation, require communication technologies that combine long transmission ranges and energy efficiency. Recent and future trends make Long Range Wide Area Network (LoRaWAN) and Narrowband-IoT (NB-IoT) the most prospective drivers of the IoT business. In this paper, after discussing the main features of the two technologies, we carry out a fair quantitative comparison between the two, investigating different performance indicators, in order to guide designers in the selection of the most appropriate technology, depending on the application requirements
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