Experimental Research on Narrowband Interference Suppression of GNSS Signals

The navigation satellites are running at a high altitude of 20000 km from the ground, and the satellite signals arriving at the ground are very weak, such as the C/A code on the L1 band, which is only -160 dBW. In complex urban environments, especially when there is an occlusion, the signal power will be even lower. Low power causes the signal to be easily disturbed, where suppressed interference is the most common method of interference. The purpose of this paper is to experiment with the BPSK and BOC signal system to do the narrowband suppression of interference analysis and set up the actual test environment, based on the commonly used LMS algorithm for the two systems of narrowband interference performance contrast analysis, and throughout the simulation, it can be seen that the two improved algorithms can effectively suppress narrowband interference, thus improving the anti-interference performance of satellite navigation receiver.

Error Performance of Subsampling Digital Power Estimation for Integrated Receivers

Estimation of signal power levels at the output of integrated receiver building blocks is a vital function as the block voltage or power gains are set based on sensed power levels to maintain constant levels at block outputs in the receiver chain. RF and IF level real-time gain settings are determined with Automatic Gain Control (AGC) loops. AGC loop circuit topologies are usually based on analog detection circuits. These analog power detection circuits are based on techniques such as envelope detection, and logarithmic amplification usually accompanied by severe accuracy issues such as Process, Voltage and Temperature (PVT) spreads preventing correct gain adjustments. Adopting a dominantly digital approach to detect the signal power would ensure a significant reduction in PVT spreads. This work presents a review of the subsampling digital power estimation to create low power digital power estimations alternative to analog methods. The simulations of the method are applied to an AM and a 64-QAM signal. Simulation results show that the power estimation error is within the acceptable level of [Formula: see text][Formula: see text]dB.

Signal power and energy-per-bit optimization problems in systems mMTC

Introduction: Currently, the issues of Internet of Things technology are being actively studied. The operation of a large number of various self-powered sensors is within the framework of a massive machine-type communication scenario, using random access methods. Topical issues in this type of communication are how to reduce the transmission signal power and to increase the device lifetime by reducing the consumed energy per bit. Purpose: Formulation and analysis of the problems of minimizing the transmission power and consumed energy per bit in systems with or without retransmissions in order to obtain the achievability bounds. Results: A model of the system is described, within which four problems are formulated and described, concerning the signal power minimization and energy consumption for given parameters (the number of information bits, the spectral efficiency of the system, and the Packet Delivery Ratio). The numerical results of solving these optimization problems are presented. They make it possible to obtain the achievability bounds for the considered characteristics in systems with or without losses. The lower bounds obtained by the Shannon formula are also presented, assuming that the message length is not limited. The obtained results showed that solving the minimization problem with respect to one of the parameters (signal power or consumed energy per bit) does not minimize the second parameter. This difference is most significant for information messages of a small length, which is common in IoT scenarios. Practical relevance: The results obtained allow you to assess the potential for minimizing the transmission signal power and consumed energy per bit in random multiple access systems with massive machine-type communication scenarios. Discussion: The presented problems were solved without taking into account the average delay of message transmission; the introduction of such a limitation should increase the transmitted signal power and consumed energy per bit.

Comparison of 1480 nm and 980 nm-pumped Gallium-Erbium fiber amplifier

Background: One way to reduce the length of the gain medium in Erbium-Doped Fiber Amplifier (EDFA) is by doping the fiber core with a high concentration of Erbium. However, this method caused ion clustering effects, which limits the EDFA’s efficiency. In this research, the use of Gallium as a new co-dopant in erbium-doped silica fiber is explored. Methods: The new fiber, namely Gallium co-doped Erbium fiber (Ga-EDF), is used as a gain medium in an optical fiber amplifier setup. A 2-meter length of the Ga-EDF fiber was used in a single pass configuration with a forward pumping scheme at 150 mW pump power. The Ga-EDF amplifier's gain and noise figure while pumping at 980 nm and 1480 nm were compared. The amplifier's performance was evaluated as the input signal power varied between -30 dBm to 3 dBm, over the wavelength range of 1520 nm to 1580 nm. Results: The 980 nm-pumped Ga-EDF amplifier achieved the maximum small-signal gain of 22.45 dB and the corresponding noise figure of 5.71 dB at the input signal wavelength of 1535 nm. Meanwhile, the 1480 nm-pumped Ga-EDF amplifier attained the maximum small-signal gain of 20.83 dB and the corresponding noise figure of 5.09 dB at the input signal wavelength of 1550 nm. At the input signal power below -20 dBm and the wavelength range 1520 nm to 1547 nm, the Ga-EDF performs better when pumped at 980 nm. Their performance is comparable at the input signal wavelength range between 1547 nm to 1580 nm. At the input signal power above -20 dBm, the 1480 nm-pumped Ga-EDF outperformed the 980 nm-pumped amplifier. Conclusions: The overall performance indicates that the gain saturation point of the 1480 nm-pumped amplifier is higher than the 980 nm-pumped.