GSM

What is HLR and VLR and its function in GSM

As From the Name VLR means Visitor Location Register and HLR means Home Location Register so it has all detail of subscriber so VLR has temporary details. Let’s check in detail. Home Location Register (HLR) The HLR is the reference database for subscriber parameters. Actually HLR Having all the detail like customer ID, customer number, […]

Article Topics :

location area identity, subscriber, mobile, system, hlr, vlr, authentication, home location register, visitor location register, sms details, detail bill imformation, calling details data

Basic of GSM Um,Abis and A Interface

GSM (Um) Air Interface This is the interface between the GSM mobile station and the GSM Base station. The Air interface (RF Interface) uses the Time Division Multiple Access (TDMA) technique to transmit and receive traffic and signaling information between the GSM BTS and GSM Mobile Station. The TDMA technique is used to divide each […]

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Basic of GSM Um,Abis and A Interface, Time Division Multiple Access, A interface function, Abis Interface Function, Air Interface basic, GSM Call Flow Basic, INgterface, Connection, LAPD, GSM BTS, BSC and MSC Connection

How 26 and 51 Multiframes in GSM

GSM is very complicated when we talk about its rf side and in it very complicated to understand the structure of 26 and 51 Multiframes, here my try to make you understand simply. The 26-frame Traffic Channel Multiframe in GSM The Below Figure shows the time relationship between time-slot, GSM TDMA frame, and the 26-frame […]

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Why 26 and 51 Multiframes in GSM, channel multiframe, frame, brust, control channel, channel multiframe, timeslot, traffic channel, sacch, multiframe, 51 multiframe, 26 multiframe

How PLMN Selection in GSM

When the mobile is switched on it will select the registered PLMN in the mobile if there exist one. If there is no registered GSM PLMN or the registered PLMN is not available (no coverage) then the GSM mobile will try to select another GSM PLMN either automatically or manually depending on it mode. AUTOMATIC […]

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plmn, GSM PLMN, automatic mode, manual mode, plmn selection, gsm, mobile, priority, network, signal, message

What is Speech Coding

The coding mode is called Regular Pulse Excited-Long Term Prediction (RPE-LTP). It works as follow: 8KHZ of sampling is performed first, then divided into frames with 20ms; every frame has 4 sub-frames; the duration of every sub-frame is 5ms; and the pure bit rate is 13kbit/s. The voice compression coding technique is widely used in […]

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voice coder, voice, coding, coder, bits

Fade Margin Calculation in GSM

As previously I write about fading effect in GSM here I write about Fade Margin Calculation in GSM. Cell area probability (CAP ) is the percentage of the cell area that has signal strength greater than the receiver sensitivity. CAP is dependent on the radio environment, primarily the standard deviation of the log normal faded […]

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fade margin, standard deviation, propagation constant, standard, propagation, margin, deviation, constant, signal

Site Selection Criteria in GSM

Site selection is based on a number of criteria. It may not be possible to satisfy all these criteria at the same time, but it is important to select the best sites available. Drive test sites should be selected to give a good representative sample of the system coverage area. The exact number of sites […]

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site selection, drive test, site, tower, antenna, urban, terrain, propagation

Antenna Installation and Downtilting

When we talk about antenna then we need to understand about antenna installation and specially about antenna downtilting.lets assume that antenna installed then how you can change its position. Its two type, left-right = its called azimuth change. up-down = its called tilt change. Lets understand from start. ANTENNA INSTALLATION Antenna installation configurations depend on […]

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downtilt, downtilting, horizon, electrical, mechanical, lobe, cell, antennas, pattern

What is Principle for Frequency Planning in GSM

The actual frequency planning of certain areas is usually conducted with such areas divided into segments geographically, i.e., first divide a complex network into small networks. However, there should be some frequency carriers (when the frequency is enough) reserved at the boundary of the segments or the frequency carriers should be divided. Such boundary should […]

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frequency planning, frequency hopping, frequency, bts, reuse, planning, hopping, channel

How 1x 3 or 1x1Reuse Patterns in Frequency Planing

Isolated reuse technology refers to 1*3 or 1*1 reuse with short reuse distance and severe interferences, radio frequency hopping technology has to be adopted. The aggregate of hopping frequencies needs to be far more larger than the number of TRX (more than twice), MA, HSN and MAIO parameter are used to avoid frequency conflict. Let’s […]

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frequency hopping technology, frequency, carriers, hopping, cell, isolated, frequency hopping, radio frequency

GSM Underlaid Overlaid Frequency Allocation and Configuration

Underlaid Overlaid  Frequency Allocation In the Overlaid/Underlaid technology, all frequency carriers in the cell are divided into two parts, of which the TRX power of some frequency carriers is lowered, then two Overlaid/Underlaid with different coverage appear, as shown in the below figure. The frequency carriers used by the inner circle can be planned in […]

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overlaid underlaid frequency configuration, overlaid underlaid, frequency carriers, frequency, underlaid, overlaid, carriers, layer, circle, cell

Advantages of Multi layer frequency Reuse Pattern

Capacity increase when reuse density is multiplied: Supposing there are 300 cells Bandwidth: 8 MHz (40 frequency) Normal 4*3 reuse: reuse density=12 Network capacity = 40/12 * 300 = 1000 TRX Multiple reuse: “0” BCCH layer: re-use =14,  (14 frq.) “+” Normal TCH layer: re-use =10, (20 frq.) ” ^-“ Aggressive TCH layer: re-use = […]

Article Topics :

co channel reuse distance, different frequency carriers, baseband frequency hopping, reuse density, frequency, carriers, layer, density, network, interferences

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