RF system for mmWave massive MIMO

Due to rapid developments in communication technology, it is likely that 5G networks will be rolled out in 2019. To adapt to 5G, hardware will have to develop to meet the requirements of this new technology. The mmWave communication is one of the main elements of 5G technology. The mmWave frequency bandwidth is used to carry the data links and can achieve a higher transmission data rate than the current LTE system. There are few continuous frequency resources under 3GHz that can be allocated. As such, the International Telecommunication Union (ITU) and the 3GPP organization mutually agree that the mmWave is the most suitable option for exploring new frequency resources. However, the mmWave has the one key weakness: high path loss for short transmission range. To compensate for this negative effect, a massive MIMO system can be used to have spatial multiplexing gains and array an-tenna gains. This article seeks a method that can acknowledge the funda-mental concepts and requirements of the mmWave massive MIMO system, from both theoretical and practical perspectives. In order to find proof of the concepts, the practical limitations, and the guild of the real design, a prototype of the system has been built. The current industry standard when creating a prototype is to use PCB. We will develop our system proposals from the prototype. To do so we use the evaluation boards to test system level performances such as link budget and identifying the most suitable components etc. Then in the PCB design, we integrate the radio frequency of the mmWave system. This has the scalability to collaborate with massive MIMO system test-bed to observe the system level performance. Finally, to verify our methods, we carry out experiments on both component level and system level in order to identify the feasibility of the prototype system. The performance of each individual component is tested using an evaluation board. Separate tests are performed for both transmitting (Tx) and receiving (Rx) chains. Finally, over-air-tests are conducted at the sys-tem level to evaluate the performance of our design5G communication system is the next milestone that will soon approach our lives. The first specification of 5G is called Release 15 and the system struc-tures and requirements of it have been identified. Compared to the LTE system, it can deliver an even higher data rate and adapt more transmission situations in the future. 5G consists of five essential technologies, mmWave, massive MIMO, the advanced channel coding, scalable OFDM and self-contained slot structure. The first two technologies, the mmWave and massive MIMO, are indispensable in this thesis. As the fre-quency resources scarcely go below 3GHz, they are retrieving the mmWave spectrum to allocate more accessible bandwidth. Nevertheless, the mmWave has high free space path loss, and the signal will be harshly weakened before it reaches the receiver. The massive MIMO is an extension of the MIMO system with massive antenna elements in the antenna array This sound solution can contradict the high free space path loss, achieve high throughput and serve tens of users simultaneously. This thesis concentrates on building a radio frequency system PCB prototype based on mmWave and massive MIMO. Now, the existing hardware devices will not placate the 5G system necessi-ties. The new system structure must be developed, and the performance will be evaluated. Prototype is a realization method to transition from theory to practice which can help the engineers comprehend the theoretical and prac-tical perspectives. In electronic industry, PCB is the correct way of building the radio frequency prototype, in which the system schematic is construct-ed in a dense area with mass circuit distribution. All electronic components are surfaced and then mounted on it and connected by conductive wires through the various layers. A flawless PCB needs to be shaped with full operational functions before the final products. To do this, the perfor-mance will be evaluated when we are building the PCB prototype and im-provements will be analysed, and additional developments will be encom-passed in the future version of PCB. In this thesis, the PCB performance is evaluated individually for different transmission chains, and then the over air test is assessed

Bending Behaviour Analysis of Aluminium Profiles in Differential Velocity Sideways Extrusion Using a General Flow Field Model

The work in this paper concerns an analytical model for quantitatively describing the bending behaviour of aluminium profiles produced in a novel extrusion process: the differential velocity sideways extrusion (DVSE), in which two opposing rams with a velocity of v1 and v2 were employed, respectively. The analytical model was built on the basis of the upper bound theorem utilising a general streamline equation controlled by a shape factor n, and the curvature was calculated using the material flow velocity gradient across the die exit orifice. The predicted material flow velocity across the die exit orifice, and extrudate curvature agreed well with the finite element (FE) modelling results, which were found to be irrespective of the shape factor n of the streamline equation. For a given extrusion ratio, the minimum value of n = 2 leads to the minimum and closest theoretical extrusion pressure, the n value for obtaining the best approximated mean effective strain of the extruded profile increases with the increase of the velocity ratio v2/v1 , and the value of n = 3.5 gives the closest mean effective strain as a whole

Effect of LiYO2 on the synthesis and pressureless sintering of Y2SiO5

Y2SiO5 has potential applications as a high-temperature structural ceramic and environmental/thermal barrier coating. In this work, we synthesized single-phase Y2SiO5 powders utilizing a solid–liquid reaction method with LiYO2 as an additive. The reaction path of the Y2O3/SiO2/LiYO2 mixture with variation in temperatures and the role of the LiYO2 additive on preparation process were investigated in detail. The powders obtained by this method have good sinterability. Through a pressureless sintering process, almost fully dense Y2SiO5 bulk material was achieved with a very high density of 99.7% theoretical

Stability Enhancement for Single-Loop Voltage Controlled Voltage-Source Converters with LC-Filter

Voltage controlled voltage source converters (VSCs) have been widely applied in microgrids, uninterruptible power sources, smart transformer and 400 Hz ground power units for airplanes, etc. An LC filter is generally adopted to attenuate high frequency switching harmonic and to improve the qualities of output voltage and current for grid or loads. Nevertheless, VSCs have to trade-off between the stability characteristic and the ability of switching harmonics suppression when a single-loop voltage control method is adopted. In general, the resonant frequency ω r of LC filter should be less than 1/4 of sampling frequency ω s to ensure sufficient attenuation of the switching harmonic. However, ω r should be higher than 1/3 of ω s for the system stability when a proportional-resonant (PR) controller with a positive proportional gain is implemented. This paper proposes a feedback of modulation voltage (FMV) control design method for single-loop control to ensure stability condition in a higher frequency range and good switching harmonics suppression at the same time. Finally, simulation results are provided to verify the effectiveness of the proposed method

VibEmoji: Exploring User-authoring Multi-modal Emoticons in Social Communication

Emoticons are indispensable in online communications. With users’ growing needs for more customized and expressive emoticons, recent messaging applications begin to support (limited) multi-modal emoticons:, enhancing emoticons with animations or vibrotactile feedback. However, little empirical knowledge has been accumulated concerning how people create, share and experience multi-modal emoticons in everyday communication, and how to better support them through design. To tackle this, we developed VibEmoji, a user-authoring multi-modal emoticon interface for mobile messaging. Extending existing designs, VibEmoji grants users greater flexibility to combine various emoticons, vibrations, and animations on-the-fly, and offers non-aggressive recommendations based on these components’ emotional relevance. Using VibEmoji as a probe, we conducted a four-week field study with 20 participants, to gain new understandings from in-the-wild usage and experience, and extract implications for design. We thereby contribute to both a novel system and various insights for supporting users’ creation and communication of multi-modal emoticons