Система бездротового зв'язку 5G

Мета статті — проаналізувати архітектурні особливості, методи комунікації та завдання, покладені в основу проектування технології 5G. Результати. Показано, які конкретні технічні та технологічні проблеми повинні бути вирішені для досягнення широких можливостей мобільного зв'язку 5G. Водночас, технологію 5G незабаром буде стандартизовано та впроваджено у всьому світі, включаючи Україну. Можливість підключення безлічі зовнішніх пристроїв в умовах електромагнітних перешкод з використанням LTE-з'єднань у разі розподілення по великій площі та за суворих вимог до затримок виконання технологічних процесів дає змогу стверджувати, що технологія бездротового зв'язку 5G є необхідною і незамінною в дослідженнях і виробництві.Цель статьи — проанализировать архитектурные особенности, методы коммуникации и задачи, положенные в основу проектирования технологии 5G. Результаты. Показано, какие конкретные технические и технологические проблемы должны быть решены для достижения широких возможностей мобильной связи 5G. Вскоре технология 5G будет стандартизирована и внедрена во всем мире, включая Украину. Возможность подключения множества внешних устройств в условиях электромагнитных помех с помощью LTE-соединений в случае распределения на большой площади и при суровых требованиях к задержкам технологических процессов позволяет утверждать, что беспроводная технология 5G является необходимой и незаменимой в исследованиях и производствеThe purpose of the paper is to describe in an accessible way the architectural features, communication methods, the Internet and the tasks that underlie 5G. Results. It is shown that specific technical and technological problems have to be solved in order to reach the wide possibilities of 5G mobile communication. At the same time, 5G technology will soon be standardized and implemented around the world, including Ukraine. The ability to connect many external devices in conditions of electromagnetic interference using LTE connections in the case of distribution over a large area and with strict requirements for process delays makes it possible to state that 5G wireless technology is necessary and indispensable in research and production

Field programmable gate array based multiple input multiple output transmitter

MIMO is an advanced antenna technology compared to Single Input Single output (SISO), Multiple Input Single Output (MISO), and Single Input Multiple Output (SIMO) and is used to obtain high data rate in the system. Multiple-Input Multiple-Output (MIMO) systems have at least two transmitting antennas, each generating unique signals. However some applications may require three, four, or more transmitting devices to achieve the desired system performance. This thesis describes a comparison between different approaches like the microcontroller, ASICs and the FPGA available in the market for baseband signal generation. It also describes the design of a scalable MIMO transmitter, based on field programmable gate array (FPGA) technology that was selected among the processors due to its capability to provide reconfigurable hardware and software. Each module of the MIMO transmitter contains a FPGA, and associated digital-to-analog converters, I/Q modulators, and RF amplifiers needed to power one of the MIMO transmitters. The system is designed to handle up to a 10 Mbps data rate, and transmit signals in the unlicensed 2.4 GHz ISM band --Abstract, page iii

Performance enhancement of wireless communication systems through QoS optimisation

Providing quality of service (QoS) in a communication network is essential but challenging, especially when the complexities of wireless and mobile networks are added. The issues of how to achieve the intended performances, such as reliability and efficiency, at the minimal resource cost for wireless communications and networking have not been fully addressed. In this dissertation, we have investigated different data transmission schemes in different wireless communication systems such as wireless sensor network, device-to-device communications and vehicular networks. We have focused on cooperative communications through relaying and proposed a method to maximise the QoS performance by finding optimum transmission schemes. Furthermore, the performance trade-offs that we have identified show that both cooperative and non-cooperative transmission schemes could have advantages as well as disadvantages in offering QoS. In the analytical approach, we have derived the closed-form expressions of the outage probability, throughput and energy efficiency for different transmission schemes in wireless and mobile networks, in addition to applying other QoS metrics such as packet delivery ratio, packet loss rate and average end-to-end delay. We have shown that multi-hop relaying through cooperative communications can outperform non-cooperative transmission schemes in many cases. Furthermore, we have also analysed the optimum required transmission power for different transmission ranges to obtain the maximum energy efficiency or maximum achievable data rate with the minimum outage probability and bit error rate in cellular network. The proposed analytical and modelling approaches are used in wireless sensor networks, device-to-device communications and vehicular networks. The results generated have suggested an adaptive transmission strategy where the system can decide when and how each of transmission schemes should be adopted to achieve the best performance in varied conditions. In addition, the system can also choose proper transmitting power levels under the changing transmission distance to increase and maintain the network reliability and system efficiency accordingly. Consequently, these functions will lead to the optimized QoS in a given network

Design and implementation of adaptive baseband predistorter for OFDM nonlinear transmitter. Simulation and measurement of OFDM transmitter in presence of RF high power amplifier nonlinear distortion and the development of adaptive digital predistorters based on Hammerstein approach.

The objective of this research work is to investigate, design and measurement of a digital predistortion linearizer that is able to compensate the dynamic nonlinear distortion of a High Power Amplifier (PA). The effectiveness of the proposed baseband predistorter (PD) on the performance of a WLAN OFDM transmitter utilizing a nonlinear PA with memory effect is observed and discussed. For this purpose, a 10W Class-A/B power amplifier with a gain of 22 dB, operated over the 3.5 GHz frequency band was designed and implemented. The proposed baseband PD is independent of the operating RF frequency and can be used in multiband applications. Its operation is based on the Hammerstein system, taking into account PA memory effect compensation, and demonstrates a noticeable improvement compared to memoryless predistorters. Different types of modelling procedures and linearizers were introduced and investigated, in which accurate behavioural models of Radio Frequency (RF) PAs exhibiting linear and nonlinear memory effects were presented and considered, based on the Wiener approach employing a linear parametric estimation technique. Three new linear methods of parameter estimation were investigated, with the aim of reducing the complexity of the required filtering process in linear memory compensation. Moreover, an improved wiener model is represented to include the nonlinear memory effect in the system. The validity of the PA modelling approaches and predistortion techniques for compensation of nonlinearities of a PA were verified by several tests and measurements. The approaches presented, based on the Wiener system, have the capacity to deal with the existing trade-off between accuracy and convergence speed compared to more computationally complex behavioural modelling algorithms considering memory effects, such as those based on Volterra series and Neural Networks. In addition, nonlinear and linear crosstalks introduced by the power amplifier nonlinear behaviour and antennas mutual coupling due to the compact size of a MIMO OFDM transmitter have been investigated