# GSM

GSM technology, GSM RF optimization, GSM Planning and How GSM Works.

## What is Channel Coding

To check and correct errors during the transmission, redundancy data and the information calculated from the source data are added to the stream so as to increase the bit rate.

## 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)

## 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

## 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

## 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

## 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

## 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

## 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

## 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

## 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

## GSM Underlaid Overlaid Frequency Allocation and Configuration

Underlaid OverlaidĀ  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,

## 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