RF Drive Test Self Learning Tutorial With Video
Contents • • • • • •
What is RF Drive Test? Why RF Drive Test is Done? Tools & Equipment required How RF DT is carried out? Cases & Analysis See it yourself (Video) & Learn
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RF Drive Test • Drive Test is one of the most comprehensive procedures of testing and analyzing a Radio Frequency Network – Coverage evaluation – System availability – Network capacity – Network retainability – Call quality 3
RF Drive Test • Let us understand the meaning of the terms mentioned in the previous slide – Coverage Evaluation – Coverage Evaluation is the process of measuring the Received Signal Level of the Radio Frequency Signals from a Base Station – The following slides will explain this in detail
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RF Drive Test • Coverage Evaluation: • A cellular mobile network in a city/town or a rural area is made up of several RF transmitting and receiving stations called Base Stations or Base Transcievers. 5
RF Drive Test • Coverage Evaluation: • Each cell has its own transmitting and receiving equipment that covers a certain geographic area • As shown each circle represents a cell
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RF Drive Test • Coverage Evaluation: • A group of cells together form a cluster • The demography of the cells, for example, the type of terrain – whether hilly or plain, vegetation or buildings etc., is known as clutter.
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RF Drive Test • Coverage Evaluation: • Clutter data of a cell and of the geographic area to be covered is very important to estimate the actual area that will be covered by a Base Station • The picture on the right shows a sample clutter data – 3D view of an area
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RF Drive Test • Coverage Evaluation: • Radio Frequency signals from a Base Station towards the mobile station and those from the mobile station towards the base station suffer due to the clutter.
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RF Drive Test • Coverage Evaluation: • They tend to – Become weaker sometimes – Become stronger sometimes – Get lost due to absorption or total reflection
• This affects the actual coverage area of a Base Station 10
RF Drive Test • Coverage Evaluation: • Let us examine some of the situations occurring due to the clutter – Deflection is the result of the Radio Frequency wave encountering obstructions with much larger dimensions than the wavelength of the radio wave. This results in the wave rebounding. 11
RF Drive Test • Coverage Evaluation: – Diffraction occurs when radio waves encounter the edges and corners of obstacles. These act as secondary sources reradiating beyond what is known as line-of-sight into the shadow region of the obstacle.
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RF Drive Test • Coverage Evaluation: – Diffusion (Scattering) occurs when the dimensions of the object (usually vegetation) interacting with the radio wave are similar to the impinging wave’s wavelength. This causes the signal to disperse.
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RF Drive Test • Coverage Evaluation: – Therefore in practical scenarios, the signal level from a Base Station at any two points in the cell even being at the same distance from the Antenna, will not be the same due to the clutter variations 14
RF Drive Test • Coverage Evaluation: – To understand these effects, let us first study in brief, how the Radio Frequency Signals propagate through Air.
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RF Drive Test • Coverage Evaluation: – RF Propagation – Primarily there are four ways of transmission of radio waves between the transmitter and the receiver in free space or through Air
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RF Drive Test • Coverage Evaluation: – RF Propagation – As a Forward or Free Space Wave – Earth Wave or Surface Wave – Troposphere reflecting Wave – Ionosphere Reflecting Wave 17
RF Drive Test • Coverage Evaluation: – RF Propagation – As a Forward or Free Space Wave • Free Space Wave moves in straight lines directly between the transmitter and receiver • Used for Line of Sight Microwave Communication
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RF Drive Test • Coverage Evaluation: – RF Propagation – As a Ground or Surface Wave • Waves reach the receiver directly and also after reflecting from earth surface and other obstructions etc. • This method is used in Cellular Mobile Communication 19
RF Drive Test • Coverage Evaluation: – RF Propagation – As a Troposphere Reflecting Wave • Waves reach the receiver after reflecting from troposphere • This method is used for waves with wavelengths less than 10 meters
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RF Drive Test • Coverage Evaluation: – RF Propagation – As a Ionosphere Reflecting Wave • Waves reach the receiver after reflecting from ionosphere. • It is used for waves having frequencies of more than 300MHz
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RF Drive Test • Coverage Evaluation: – RF Propagation – Two reasons why propagation study is important • It helps in calculating the signal levels within a cell or you can say it helps predicting the coverage of a cell.
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RF Drive Test • Coverage Evaluation: – RF Propagation – Two reasons why propagation study is important • Secondly, it helps determining the adjacent channel and co channel interference.
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RF Drive Test • Coverage Evaluation: – RF Propagation – There are three methods of predicting signal level coverage in a cell. • The First one is based upon pure theory.
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RF Drive Test • Coverage Evaluation: – RF Propagation – There are three methods of predicting signal level coverage in a cell. • The First one is based upon pure theory. • It does not take into account the irregularity of the earth’s surface 25
RF Drive Test • Coverage Evaluation: – RF Propagation – There are three methods of predicting signal level coverage in a cell. • The Second one is based upon measurements in different environments.
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RF Drive Test • Coverage Evaluation: – RF Propagation – There are three methods of predicting signal level coverage in a cell. • The Third method is based upon theoretical and actual measurement basis. • There are various models that are used. 27
RF Drive Test • Coverage Evaluation: – RF Propagation – There are various parameters and phenomena that are required to be studied to understand RF Propagation. • Multipath Fading
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RF Drive Test • Coverage Evaluation: – RF Propagation – There are various parameters and phenomena that are required to be studied to understand RF Propagation. • Propagation Loss
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RF Drive Test • Coverage Evaluation: – RF Propagation – There are various parameters and phenomena that are required to be studied to understand RF Propagation. • Diffraction or Shadowing
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RF Drive Test • Coverage Evaluation: – RF Propagation – There are various parameters and phenomena that are required to be studied to understand RF Propagation. • Building & Vehicle Penetration • Type of Terrain 31
RF Drive Test Further Slides Available in Commercial Tutorial In case you are interested to buy, please write back at
[email protected] The full tutorial consists of over 500 slides and a video 32
