TelecomStudy18

Erlang :   An Erlang is a unit of telecommunications traffic measurement.  Strictly speaking, an Erlang represents the continuous use of one voice path.  In practice, it is used to describe the total traffic volume of one hour.  in other words " a one ckt  can one hour of traffic is known as 1Erlang" For example, if a group of user made 30 calls in one hour, and each call had an average call duration of 5 minutes, then the number of Erlangs this represents is worked out as follows: Minutes of traffic in the hour = number of calls x duration Minutes of traffic in the hour = 30 x 5 Minutes of traffic in the hour = 150 Hours of traffic in the hour = 150 / 60 Hours of traffic in the hour = 2.5 Traffic figure = 2.5 Erlangs The main Erlang traffic model are listed below    Erlang B This is the most commonly used traffic model, and is used to work out how many lines are required if the traffic f...

GSM Architecture

Channel concepts: There are two types of channel in GSM Network - Control channel and Traffic channel:   The traffic Channels:   are used to transport encoded speech and data information. Full rate traffic channels TCH/F are defined using a group of 26 TDMA frames called a 26 frame multi-frame. The 26 frame multi-frame lasts 120ms and the traffic channels for the downlink and uplink are separated by three bursts. The TCH/F consists of one time slot in each TDMA frame i.e., one slot every 4.615ms. The control Channels: are used for network management messages (call set up, control signaling etc.) and some channel maintenance tasks. These can be subdivided into BCH (Broadcast Channel), CCCH (Common Control Channel), and DCH (Dedicated Channel) BCH: BCCH, FCCH, SCH / CCCH: RACH, AGCH, PCH / DCH: SDCCH, SACCH, FACCH, CBCH BCCH (Broadcast channel): Its downlink channel is used for transmitting of system information unique BCCH define for entire cell and i...

KPI (Key Performance Indicator) TCH Drop : disconnect a unwanted call is known as TCH drop    [TCH Drop = (TNDROP)/TCASSAL*100] SDCCH Drop Rate = [(CNDROP-CNRELCONG)/ (CMSESTAB)]*100 % SDCCH Blocking = (CCONGS)\(CCALLS)*100 TASR = (TCASSAL) / (TASSALL) *100 HOSR = (SUMOHSUCC+SUMEOHSUCC)/ (SUMOHOATT+SUMEOHATT)*100 Random Access Success Rate = (CNROCNT)/ (CNROCNT+RAACCFA) * 100 RAACCFA: Failed Random Access CNROCNT: All accepted Random Access TCH DROP HO FAIL DLQ Low Signal strength DL & UL Less,   Many or   Mismatch NBR BCCH & TCH Frequency Interference Bad Quality DL & UL TCH Cong at target cell Interference or error   on E1 High TA Low SS or Bad Qual on cell border Mismatch MAIO & HSN Bad Parameter regulation Mismatch HO algorithm Hardware Issue, faulty or Alarm High ICM, VSWR or path imbalance Mismatch HO parameter setting   Antenna Faulty/ feeder E1 error & Tr...