What is MIMO Communication in 4G and WiFi Networks ?

Recently, the wireless communication systems have been transformed and now they have more robust communication link and higher spectral efficiency. One of the main improvement, which has been implemented into current 4G and WiFi networks, is MIMO (Multiple-Input Multiple-Output) technique.

MIMO communication networks include more than one transmitter and receiver antennas in order to use multiple channel at the same time and frequency resources. The idea behind this technique is each antenna port can have a separate channel due to reflection and the scattering of the microwaves during the propagation. These channels are utilized using software based receivers and equalizer in order to simultaneously transmit data.

MIMO enhances the spectral efficiency, thus the capacity of the link besides providing more communication links.  

Polarisation of Electromagnetic Waves

The polarisation of electric field states the orientation and magnitude of its field vectors and their alteration through the time. Polarisation is related to the transverse electromagnetic waves (TEM), in which directions and magnitudes of both electric and magnetic fields vary by time. Polarisation of EM waves from an antenna is classified into three main categories: linear, circular or elliptical polarisations. Furthermore, the direction of polarisation may be clockwise (CW, right-hand polarisation) or counter-clockwise (CCW, left-hand polarisation). For instance, the equation indicates a circularly polarized wave which consists of two components in the x and y directions. If polarisation of the receiver antenna does not match with the polarisation of incoming waves, the amplitudes of the received waves decrease. This polarisation mismatch will cause polarisation loss and reduce the power of the received signal. On the other hand, polarisation discrepancy can be employed to transmit two signals simultaneously at the same frequency-time resources using two different polarisations such as in satellite communication.

Antenna polarisation is another opportunity for MIMO systems. Because the vertical and horizontal polarisation may be utilized to increase the number of antennas in a given area. Single polarized and dual polarized 2\times2 MIMO systems have been compared [1], in which they show that if there is a high correlation between two antennas, then polarized MIMO have better performance over a single polarized system. In another similar study, they perform broadband outdoor channel measurement to verify the performance of 2x3 dual-polarized MIMO system at 2.5 GHz frequency and they achieved higher capacity using dual polarisation especially in the close range. On the other hand, aforementioned two studies demonstrate that if the distance between transmitter and receiver is large enough, then single polarised MIMO system performs better than the dual polarised system.

Graphene enhanced devices simulation based design microwave optical frequencies | Video

Graphene is a material with extraordinary properties. It promises to open up new application areas or to enhance existing devices, as indicated by a large amount of research on this topic. Currently, commercial applications are still small in number but increasing. EM simulations are a formidable tool to aid in the research and design of new devices that employ graphene.

Artificial Intelligence with Python and Machine Learning examples

Firstly, the theory of the Artificial Intelligence and then you will find some useful examples of how to use Python for Machine learning and artificial intelligence applications.

Note, before using them, you will probably have to install some packages (e.g. TensorFlow) on your computer.

Simulation of electromagnetic wave with Python

Antenna arrays and python

 These links include information about how to model and calculate patch antenna arrays using python:

  1. https://medium.com/@johngrant/antenna-arrays-and-python-introduction-8e3b612ecdfb
  2. https://medium.com/@johngrant/antenna-arrays-and-python-square-patch-element-6bd3445f39d5
  3. https://medium.com/@johngrant/antenna-arrays-and-python-the-array-finally-3613966153d7
  4. https://medium.com/@johngrant/antenna-arrays-and-python-plotting-with-pyplot-ae895236396a
  5. https://medium.com/python-pandemonium/antenna-arrays-and-python-calculating-directivity-84a2cfea0739

I would like to remind you that in feeding a patch antenna, the location of the feed point determines the patch's input impedance at the resonance frequency. If feeding with standard 50Ohm SMA connectors, the input impedance of the patch should be adjusted to approx. 50Ohm for optimum matching.Now keep in mind that you don't want the feed location to be neither at the edge of the patch nor at the center. The reason is that (using the cavity model for analyzing the patch and assuming the dominant mode) the E field is zero at the center of the patch (so this would give you zero input impedance) and maximum at the edges (implying very high input impedance). So you generally want to be somewhere in between the edge and the middle to achieve 50Ohm.The rule of thumb is approx 1/3 of the distance between the two edges.Any book for microstrip antennas should have the formulas you need to find the location of the feed point, to obtain precisely 50Ohm input impedance. My calculation gave me that you need to place your feed at about 12.88 mm from the edge.

Video Game Industry in The World

One of the biggest digital industries in the world is the game industry which includes mobile games, console games and PC games.  UK, USA, Japan, Canada, Korea and China have huge market shares in this industry.

Market Share of Game Development around the world. [1]

The web pages below present market share of the game industry by countries and which countries are leading this industry.

  1. http://www.gameindustrycareerguide.com/best-cities-for-video-game-development-jobs/
  2. https://www.gamedesigning.org/game-development-studios/
  3. https://www.gamedevmap.com/     gives extensive information about which company is in which city/country
  4. https://venturebeat.com/2014/06/24/gamer-globe-the-top-100-countries-by-2014-game-revenue/
  5. http://uk.businessinsider.com/coolest-video-game-companies-in-europe-2015-7/#hello-games-is-working-on-a-game-loved-by-both-kanye-west-and-elon-musk-31


Japan Graduate School Directory
04 Nov 2016

via this link we can conduct MSc or PhD programs in Japan.

Ultra Wideband Antenna Design for Target Detection
04 Nov 2016
Abstract—In this paper, a four-element microstrip antenna array is presented. The array is composed of Wilkinson power dividers which act as feed network along with Dolph-Chebyshev distribution and four identical patch antenna elements. The array elements are properly designed to have a compact size and constant gain against frequency. The simulated results show good agreement with the measured results for the fabricated antenna array. Measurement shows that the array has a peak gain of more than 12 dBi with side-lobe level of −15 dB at 6 GHz. These characteristics make the antenna array suitable for UWB directional uses.

Antenna Design for Wireless Sensor Networks

Wireless sensor networks have been becomıng more important with each passing day. For example, Internet of things (IoTs) concept is developed actually based on WSN systems. There are many different potential and future applications of WNS such as in industry, defence or protecting nature.

One wireless sensor network node may include a wide variety of layers from physical communication layer to algorithm development. Antennas are also vital parts of the wireless sensor nodes. Due to the small size of the nodes, efficient and small antenna design is brutally challenging, many different methods, therefore, can be applied to enhance performance and efficiency of those small antenna elements.


Starting a New Design: Wireless Sensor Nodes for WSN Networks