OBTAINING CONDITIONS FOR TECHNOLOGY NEUTRALITY OF COMMUNICATION SYSTEMS WITH MINIMUM COUPLING LOSS METHOD

Background. Technology neutrality is widely used in frequency bands, where communication systems are evolving, but there are strict restrictions on the parameters and deployment of base stations of different technologies using adjacent channels. Ways to mitigate this effect have not been sufficiently studied and require further analysis and development. Objective. The purpose of this article is to investigate the methodology for obtaining technical conditions of technological neutrality with minimum coupling loss method to determine the value of additional filtering requirements and present the results of practical implementation of this technique. Methods. The method of detailed power analysis of frequency characteristics of filters for base stations’ transmitter and receiver is applied. Results. The article presents the results of obtaining minimal guard band and additional filtering requirements in the adjacent channels of transmitter and receiver belonging to different technologies. Examples of practical implementation of the minimum guard band and frequency characteristics of additional filters are given. Conclusions. The general method of determining the technical conditions for ensuring technology neutrality is presented and the value of the minimal required guard band between the adjacent transmitter and receiver channels is obtained.

Effects of the adjacent channels on IP3 and IP5 of RF amplifier

This paper discusses the impact of the adjacent channels on the 1-dB compression point, the IP3 and the IP5 of Radio Frequency (RF) amplifier by n-tone test. By combining the theoretical derivation and software simulation, the model analysis for the third/five order polynomial nonlinear amplifier has been achieved. Moreover, the control variable method is adopted to draw the curves for the input/output signals. The research shows that the 1-dB compression point, the IP3 and the IP5 drop as n increases, and they all have symmetry for a given n. The fifth-order polynomial nonlinear amplifier model is proposed, the research shows that the adjacent channels have a great impact on the 1-dB compression point, the IP3 and the IP5 of the desired channel. This effect must be taken into account in actual RF amplifier designs and wireless communication architectures.

Broadband Spectral Analysis Algorithm with High-Frequency Resolution for Elimination of Overlap Interference between Adjacent Channels

Spectral lines can be analysed to determine the physical properties of molecular clouds and the astrochemical processes in the formation area of massive stars. To improve the observation technology of radio astronomy, this paper proposes and compares two spectral analysis algorithms (improved weighted overlap-add (IWOLA) + FFT and IWOLA + weighted overlap-add (WOLA)). The proposed algorithms can obtain an ultra-high-frequency resolution for real-valued wideband signals, eliminate the signal overlapping interference between adjacent channels, substantially decrease the required hardware resources, especially multipliers, adders, and memory resources, and reduce the system design complexity. The IWOLA + FFT algorithm consists of an improved weighted overlap-add (IWOLA) filter bank, fast Fourier transform (FFT), a specific decimation for the output data from the IWOLA filter bank, and a selection for part of the output data from the FFT. The IWOLA + WOLA algorithm consists of the same modules as the IWOLA + FFT algorithm, with the second-stage FFT replaced by the modules of the weighted overlap-add (WOLA) filter bank and the accumulation for each sub-band. Based on an analysis of the underlying principles and characteristics of both algorithms, the IWOLA + FFT algorithm demonstrated a spectrum with a high frequency resolution and a comparable performance to an ultra-large-scale FFT, based on two smaller FFTs and a flexible architecture instead of a ultra-large-scale FFT. The IWOLA + WOLA algorithm contains the same function as the IWOLA + FFT algorithm and demonstrates a higher performance. The proposed algorithms eliminated the interference between the adjacent channels within the entire Nyquist frequency bandwidth. The simulation results verify the accuracy and spectral analysis performances of the proposed algorithms.

Analyzing Cognitive Radio Network Operation With the Mechanism of Deciding Handoff and Process of Handoff Employing Varied Distribution Models (5G)

Cognitive radio networks (CRNs) deal with sensing, decision making, sharing, and mobility. Among these aspects, spectrum mobility assumes a vital role for spectrum handoff to occur. When the spectrum handoff process is analyzed, there are call drops, spectrum handoff, and interferences with the adjacent channels. For minimizing the handoff of the spectrum's probability as well as the call drops, which involves three processes, which are followed in sequential order, results demonstrate a better QoS. In the following three processes, the first process starts with the Markov model that identifies a channel's states and selects the channel which is apt. The second process, multiple attributes decision making (MADM), methods choose one of the best possible channels among all the channels based on various metrics in the proposed hybrid method. In the third process, the spectrum handoff is analyzed through different distribution models to indicate which model is the desirable one for a handoff process such as the one with stationary users or the other with non-stationary users.

Reverse Design of On-Chip Terahertz Demultiplexers

The reverse design method (RDM) is a frontier direction in the optical research field. In this work, RDM is applied to the design of terahertz demultiplexers, including two-port and three-port terahertz demultiplexers, with areas of 3 mm × 3 mm and 5 mm × 5 mm, respectively. The Finite-Difference Time-Domain (FDTD) simulation results show that the terahertz waves at frequencies of 0.5 THz and 0.417 THz can be well separated by the two-port demultiplexer, and the transmittances of the two outputs reach as high as 0.75 after bandwidth optimization. Meanwhile, the three-port terahertz demultiplexer can have terahertz waves separated from three Ports, and the crosstalk between adjacent channels is less than −18 dB.

Energy-Efficient Power Allocation Using Probabilistic Interference Model for OFDM-Based Green Cognitive Radio Networks

We study the energy-efficient power allocation techniques for OFDM-based cognitive radio (CR) networks, where a CR transmitter is communicating with CR receivers on a channel borrowed from licensed primary users (PUs). Due to non-orthogonality of the transmitted signals in the adjacent bands, both the PU and the cognitive secondary user (SU) cause mutual-interference. We assume that the statistical channel state information between the cognitive transmitter and the primary receiver is known. The secondary transmitter maintains a specified statistical mutual-interference limits for all the PUs communicating in the adjacent channels. Our goal is to allocate subcarrier power for the SU so that the energy efficiency metric is optimized as well as the mutual-interference on all the active PU bands are below specified bounds. We show that the green power loading problem is a fractional programming problem. We use Charnes-Cooper transformation technique to obtain an equivalent concave optimization problem for what the solution can be readily obtained. We also propose iterative Dinkelbach method using parametric objective function for the fractional program. Numerical results are given to show the effect of different interference parameters, rate and power thresholds, and number of PUs.

Energy-Efficient Power Allocation Using Probabilistic Interference Model for OFDM-Based Green Cognitive Radio Networks

We study the energy-efficient power allocation techniques for OFDM-based cognitive radio (CR) networks, where a CR transmitter is communicating with CR receivers on a channel borrowed from licensed primary users (PUs). Due to non-orthogonality of the transmitted signals in the adjacent bands, both the PU and the cognitive secondary user (SU) cause mutual-interference. We assume that the statistical channel state information between the cognitive transmitter and the primary receiver is known. The secondary transmitter maintains a specified statistical mutual-interference limits for all the PUs communicating in the adjacent channels. Our goal is to allocate subcarrier power for the SU so that the energy efficiency metric is optimized as well as the mutual-interference on all the active PU bands are below specified bounds. We show that the green power loading problem is a fractional programming problem. We use Charnes-Cooper transformation technique to obtain an equivalent concave optimization problem for what the solution can be readily obtained. We also propose iterative Dinkelbach method using parametric objective function for the fractional program. Numerical results are given to show the effect of different interference parameters, rate and power thresholds, and number of PUs.

Cleanup and Restoration of 1000-ha of Oiled Mangroves, Bodo, Eastern Niger Delta, Nigeria

ABSTRACT A 1000 ha (2471 ac) area around the community of Bodo in Rivers State, Nigeria, was affected by two large pipeline spills in 2008 and numerous smaller discharges between 2009 and present, primarily related to oil theft, transport and indigenous refining. This paper describes the remediation of affected environments which represents the largest cleanup and restoration of a mangrove ecosystem due to oil-related damage ever undertaken and serves as a potential model for other areas of the Niger Delta similarly affected. Cleanup activities include: (1) raking / mixing of surface sediments to break up a thick algal mat and removal of heavily polluted dead mangrove debris while lesser-oiled (most common) debris is broken up and left in place to aid re-establishment of mangrove plants and animal life used as a food source by the Bodo Community; (2) pressure flushing using ambient water from adjacent channels; (3) compressed air with water from a barge-mounted system, (4) use of hard boom and sorbents around the work area to capture off-floating oil, and (5) manual collection of floating oil using sorbents and hand bailers, followed by transfer to a central collection point and disposal at a government approved facility. High-volume low-pressure flushing system proved effective in releasing much of the deeply penetrated oil without damaging the sedimentary structure of the mangrove platform. Innovative methods are continually being sought. After confirmation of cleanup requirements, former mangrove areas (~860 ha, 2125 ac) will be planted with mangrove seedlings to phytoremediate remaining oil. Close-out criteria are based upon visual assessment followed by chemical sampling to meet government approved risk-based site-specific target levels. Potential major impediments to the successful completion of this Project are community unrest, security issues and reoiling from illegal activities and pipeline operations.

Monitoring the difference in liquid levels in adjacent tanks

The possibility of synchronous monitoring of coolant levels in the cooling systems of nuclear and thermal power plants before and after the barrier mesh using a specialized level gauge is considered. The block diagram of a level gauge providing current synchronous control of liquid levels in two adjacent channels (reservoirs), as well as the difference in liquid levels in them, is presented. A feature of the structural diagram of a specialized acoustic level gauge is the use of a radiation source common to both channels and a device for dividing the common waveguide path into two channels. An algorithm for the functioning of a specialized level gauge has been developed, in which, based on time diagrams, it is shown how the level is controlled in each channel and the difference in liquid levels before and after the barrier grid is calculated. The description of the algorithm is accompanied by calculated expressions for determining the levels and the difference in liquid levels. For a level gauge made in the acoustic wavelength range, a condition is given that is necessary for the creation of a device that provides matching when dividing a common channel into two independent channels of pulse signal propagation. This condition made it possible to establish the relationship between the inner diameters of cylindrical pipes used as waveguide paths of an acoustic wave. Variants of the implementation of a specialized level gauge based on two modifications of the ZOND-3M level gauge are proposed, in which cylindrical pipes are used as waveguiding systems. It is shown that when using the AP-7VT transceiver, the level gauge will have an operating range of up to 10m with a level resolution of ± 1mm, and when using the AP-70T transceiver, it will have an operating range of up to 20m with a level resolution of ± 1cm.