scholarly journals High-speed algorithm for carrier frequency recovery and frame synchronization in QPSK-modulated modems

2018 ◽  
pp. 28-35
Author(s):  
A. V. Sadchenko ◽  
O. A. Kushnirenko ◽  
E. K. Koshelev ◽  
V. I. Bondar
Keyword(s):  
Carrier Frequency ◽  
Communication Systems ◽  
High Speed ◽  
Phase Shifter ◽  
Voltage Controlled Oscillator ◽  
Frame Synchronization ◽  
Phase Ambiguity ◽  
Circuit Realization ◽  
Simultaneous Formation ◽  
Carrier Frequency Recovery

When demodulating signals in communication systems with QPSK modulation operating in the pulsed mode, the following problems arise: rapid elimination of the reference oscillator phase ambiguity and ensuring reliable frame synchronization for a given noise immunity. In most QPSK modems, the carrier frequency recovery and synchronization recovery tasks are separated and solved with the help of different functional modules, which is not the optimal solution from the point of view of increasing the energy efficiency. In this paper, we propos a fast algorithm for frame synchronization and recovery of the carrier frequency of a QPSK modem using Barker sequences as synchronization signals in conjunction with the coordinated processing. The simulation of the combined circuit is performed, which allows to eliminate the phase ambiguity of the reference oscillation with the simultaneous formation of the frame synchronization signal for various combinations of binary sync codes of the length N = 7. To obtain a reference oscillation, a stable quartz oscillator is used. An external adjustable phase shifter block abruptly changes the phase of the oscillator, and the phase ambiguity, which is multiple of 90°, is eliminated by parallel analysis of all possible rotations of the signal constellation plane in the units, each of which contains a pair of filters matched to the signal distributed over in two quadratures. The timing for the proposed scheme does not depend on the initial phase difference between the received and the initial signal constellations, while the circuit realization of a non-tunable oscillator is much simpler than that for a voltage controlled oscillator.

scholarly journals RF-MEMS Monolithic K and Ka Band Multi-State Phase Shifters as Building Blocks for 5G and Internet of Things (IoT) Applications

Sensors ◽  
2020 ◽  
Vol 20 (9) ◽  
pp. 2612 ◽  
Author(s):  
Jacopo Iannacci ◽  
Giuseppe Resta ◽  
Alvise Bagolini ◽  
Flavio Giacomozzi ◽  
Elena Bochkova ◽  
...  
Keyword(s):  
Internet Of Things ◽  
Communication Systems ◽  
High Speed ◽  
Phase Shifter ◽  
Satellite Communication ◽  
Rf Mems ◽  
Building Blocks ◽  
Phase Shifters ◽  
Small Cells ◽  
Mems Technology

RF-MEMS, i.e., Micro-Electro-Mechanical Systems (MEMS) for Radio Frequency (RF) passive components, exhibit interesting characteristics for the upcoming 5G and Internet of Things (IoT) scenarios, in which reconfigurable broadband and frequency-agile devices, like high-order switching units, tunable filters, multi-state attenuators, and phase shifters will be necessary to enable mm-Wave services, small cells, and advanced beamforming. In particular, satellite communication systems providing high-speed Internet connectivity utilize the K and Ka bands, which offer larger bandwidth compared to lower frequencies. This paper focuses on two design concepts of multi-state phase shifter designed and manufactured in RF-MEMS technology. The networks feature 4 switchable stages (16 states) and are developed for the K and Ka bands. The proposed phase shifters are realized in a surface micromachining RF-MEMS technology and the experimentally measured parameters are compared with Finite Element Method (FEM) multi-physical electromechanical and RF simulations. The simulated phase shifts at both the operating bands fit well the measured value, despite the measured losses (S21) are larger than 5–7 dB if compared to simulations. However, such a non-ideality has a technological motivation that is explained in the paper and that will be fixed in the manufacturing of future devices.

Improving OFDM Carrier Frequency Synchronization Using Cyclic Prefix

2013 ◽  
Vol 411-414 ◽  
pp. 779-783
Author(s):  
Ju Peng Zhang ◽  
Ming Jiang Wang
Keyword(s):  
Carrier Frequency ◽  
Communication Systems ◽  
Orthogonal Frequency Division Multiplexing ◽  
High Speed ◽  
Multipath Fading ◽  
Cyclic Prefix ◽  
Packet Transmission ◽  
Frequency Synchronization ◽  
Carrier Frequency Synchronization ◽  
Improved Algorithm

Orthogonal Frequency Division Multiplexing (OFDM) is the key technology of high speed communication systems which are widely used today. Small carrier frequency offset can make OFDM system performance fell sharply. So it needs very effective carrier frequency synchronization to make sure that the system works perfect. Seen from a large number of simulations, typical algorithm requires strict symbol timing. According to this characteristic, we proposed an improved carrier frequency synchronization algorithm using cyclic prefix. The improved algorithm can achieve better performance than typical algorithm in multipath fading channel. The precision of the improved algorithm under the same Signal Noise Ratio (SNR) is about 3 orders of magnitude higher than typical algorithm. We found that improved algorithm has more excellent performance in burst packet transmission mode.

Presentation, Design and Application of a New Parallel Frame Synchronization Scheme

2013 ◽  
Vol 677 ◽  
pp. 455-459
Author(s):  
Bao Tang Shan
Keyword(s):  
Communication Systems ◽  
High Speed ◽  
Satellite Communication ◽  
Design Method ◽  
Data Communication ◽  
Decision Time ◽  
Frame Synchronization ◽  
Decision Performance ◽  
Synchronization Scheme ◽  
Parallel Frame

To solve the problems of frame sync words gotten unstably and short frame synchronization state decision time, a new parallel frame synchronization scheme is presented. The proposed method improves the robustness and state decision performance of the frame synchronization system. The method is implemented and verified in a high-speed satellite communication system. Based on that practical application, a multi-channel parallel frame synchronization design method is given for even higher speed data communication systems.

Recent Advances in Ultra-High-Speed Waveguide Photodiodes for Optical Communication Systems

2009 ◽  
Vol E92-C (7) ◽  
pp. 922-928 ◽  
Author(s):  
Kikuo MAKITA ◽  
Kazuhiro SHIBA ◽  
Takeshi NAKATA ◽  
Emiko MIZUKI ◽  
Sawaki WATANABE
Keyword(s):  
Optical Communication ◽  
Communication Systems ◽  
High Speed ◽  
Recent Advances ◽  
Ultra High Speed ◽  
Optical Communication Systems

INNOVATIVE METHOD OF SATELLITE COMMUNICATION

2019 ◽  
Author(s):  
Teodor Narytnik ◽  
Vladimir Saiko
Keyword(s):  
Communication Systems ◽  
High Speed ◽  
Satellite Communication ◽  
Radio Channel ◽  
Satellite Communications ◽  
Service Area ◽  
Satellite Systems ◽  
Orbit Satellite ◽  
Geometric Size ◽  
Distributed Satellite

The technical aspects of the main promising projects in the segments of medium and low-orbit satellite communication systems are considered, as well as the project of the domestic low-orbit information and telecommunications system using the terahertz range, which is based on the use of satellite platforms of the micro- and nanosatellite class and the distribution of functional blocks of complex satellite payloads more high-end on multiple functionally related satellites. The proposed system of low-orbit satellite communications represents the groupings of low-orbit spacecraft (LEO-system) with the architecture of a "distributed satellite", which include the groupings of the root (leading) satellites and satellite repeaters (slaves). Root satellites are interconnected in a ring network by high-speed links between the satellites. The geometric size of the “distributed satellite” is the area around the root satellite with a radius of about 1 km. The combination of beams, which are formed by the repeater satellites, make up the service area of the LEO system. The requirements for the integrated service area of the LEO system (geographical service area) determine the requirements for the number of distributed satellites in the system as a whole. In the proposed system to reduce mutual interference between the grouping of the root (leading) satellites and repeater satellites (slaves) and, accordingly, minimizing distortions of the information signal when implementing inter-satellite communication, this line (radio channel) was created in an unlicensed frequency (e.g., in the terahertz 140 GHz) range. In addition, it additionally allows you to minimize the size of the antennas of such a broadband channel and simplify the operation of these satellite systems.

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