1,980 research outputs found
Synchronization in wireless communications
The last decade has witnessed an immense increase of wireless communications services in order to keep pace with the ever increasing demand for higher data rates combined with higher mobility. To satisfy this demand for higher data rates, the throughput over the existing transmission media had to be increased. Several techniques were proposed to boost up the data rate: multicarrier systems to combat selective fading, ultra wide band (UWB) communications systems to share the spectrum with other users, MIMO transmissions to increase the capacity of wireless links, iteratively decodable codes (e.g., turbo codes and LDPC codes) to improve the quality of the link, cognitive radios, and so forth
Positioning of High-speed Trains using 5G New Radio Synchronization Signals
We study positioning of high-speed trains in 5G new radio (NR) networks by
utilizing specific NR synchronization signals. The studies are based on
simulations with 3GPP-specified radio channel models including path loss,
shadowing and fast fading effects. The considered positioning approach exploits
measurement of Time-Of-Arrival (TOA) and Angle-Of-Departure (AOD), which are
estimated from beamformed NR synchronization signals. Based on the given
measurements and the assumed train movement model, the train position is
tracked by using an Extended Kalman Filter (EKF), which is able to handle the
non-linear relationship between the TOA and AOD measurements, and the estimated
train position parameters. It is shown that in the considered scenario the TOA
measurements are able to achieve better accuracy compared to the AOD
measurements. However, as shown by the results, the best tracking performance
is achieved, when both of the measurements are considered. In this case, a very
high, sub-meter, tracking accuracy can be achieved for most (>75%) of the
tracking time, thus achieving the positioning accuracy requirements envisioned
for the 5G NR. The pursued high-accuracy and high-availability positioning
technology is considered to be in a key role in several envisioned HST use
cases, such as mission-critical autonomous train systems.Comment: 6 pages, 5 figures, IEEE WCNC 2018 (Wireless Communications and
Networking Conference
TS-MUWSN: Time synchronization for mobile underwater sensor networks
Time synchronization is an important, yet challenging, problem in underwater sensor networks (UWSNs). This challenge can be attributed to: 1) messaging timestamping; 2) node mobility; and 3) Doppler scale effect. To mitigate these problems, we present an acoustic-based time-synchronization algorithm for UWSN, where we compare several message time-stamping algorithms in addition to different Doppler scale estimators. A synchronization system is based on a bidirectional message exchange between a reference node and a slave one, which has to be synchronized. Therefore, we take as reference the DA-Sync-like protocol (Liu et al., 2014), which takes into account node's movement by using first-order kinematic equations, which refine Doppler scale factor estimation accuracy, and result in better synchronization performance. In our study, we propose to modify both time-stamping and Doppler scale estimation procedures. Besides simulation, we also perform real tests in controlled underwater communication in a water test tank and a shallow-water test in the Mediterranean Sea.Peer ReviewedPostprint (author's final draft
Waveform Design for 5G and Beyond
5G is envisioned to improve major key performance indicators (KPIs), such as
peak data rate, spectral efficiency, power consumption, complexity, connection
density, latency, and mobility. This chapter aims to provide a complete picture
of the ongoing 5G waveform discussions and overviews the major candidates. It
provides a brief description of the waveform and reveals the 5G use cases and
waveform design requirements. The chapter presents the main features of cyclic
prefix-orthogonal frequency-division multiplexing (CP-OFDM) that is deployed in
4G LTE systems. CP-OFDM is the baseline of the 5G waveform discussions since
the performance of a new waveform is usually compared with it. The chapter
examines the essential characteristics of the major waveform candidates along
with the related advantages and disadvantages. It summarizes and compares the
key features of different waveforms.Comment: 22 pages, 21 figures, 2 tables; accepted version (The URL for the
final version:
https://onlinelibrary.wiley.com/doi/abs/10.1002/9781119333142.ch2
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