When the voice signal is transmitted after being processed and modulated, the frequency hopping technique will be used too, i.e. the transmission carrier varies constantly at different timeslots (of course,
GSM
What is Interleaving
If the voice signal is modulated and transmitted directly after channel coding, due to the condition changes in mobile communication channel, a deep of the fading will influence a successive
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