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GSM
GSM RF Optimization Step by Step
Here I write about GSM RF Optimization Step by Step and how to find KPI degradation and its solution. The RF network optimization process can be categorized by the following steps: Problem analysis Analyzing performance retrieved from tool reports and…
How Interference Diversity in GSM?
Interference is dependent on time, frequency and mobile location. Without frequency hopping, some cell planning margins must be incorporated so that sufficient service quality can still be provided in an interfered situation. By changing frequency on every TDMA frame, a…
What is inside SIM Card (Subscriber Identity Module) ?
Subscriber Identity Module (SIM) The SIM as mentioned previously is a “smart card” which plugs into the ME and contains information about the MS subscriber hence the name Subscriber Identity Module. The SIM contains several pieces of information: International Mobile…
How Common Control Channel (CCCH) works in GSM ?
RACH(Random Access Channel) Uplink only. Used by the MS when making its first access to the Network. The reason for access could be initiation of a call or a page response. AGCH (Access Grant Channel) Downlink only. Used for acknowledgement…
How Adaptive Multi-Rate Codec (AMR) work in GSM ?
Adaptive Multi-Rate (AMR) codec consists of a family of codecs (source andchannel codecs with different trade-off bit-rates) operating in the GSM FRand HR channels modes The AMR system exploits the channel performance and robustness added bythe coding rates by adapting…
How Many Broadcast Channels & what’s it work in GSM ?
BCCH(Broadcast Control Channels) Downlink Only. Broadcast information of the serving cell (System Information). Transmitted on timeslot zero of BCCH carrier. Read only by idle mobile at least once every 30 secs. SCH (Synchronization Channels) Downlink Only Carries information for frame…
Basic Work of MSC (Mobile Switching Centre)
Exchange where calls are established, maintained and released Database for all subscribers and their associated features. Communicates with the BSCs on the A interface and with PSTN on fixed line. MSC is weighted on the number of subscribers it can…
Advantages of Intelligent Network (IN)
Concept of Intelligent Network: The introduction of new services and access to the GSM service are based on the concept of Intelligent Network (IN). This is because of the independence between: Conventional call processing handled by the exchange, Mobile radio…
Downlink Logical Channel in GSM
In 2G GSM Technology in forward direction Downlink (GSM BTS to GSM Mobile). There are mainly five Downlink Logical Channel in GSM. Frequency correction channel (FCCH) Synchronous channel (SCH) Broadcast control channel (BCCH) Paging channel (PCH) Access granted channel (AGCH)…
Structure of Combined BCCH in GSM
It is used in the configuration of cells of low traffic density and small capacity. The Combined BCCH is only configured at timeslot 0. Channel combination: FCCH?SCH?BCCH?CCCH+SDCCH/4+SACCH/4 SDCCH/4: Stand-alone dedicated control channel. Each TDMA multiframe with 51 frames has 4…
Structure of Main BCCH in GSM
The TDMA/FDMA multiplexing is used in GSM, the information needed in the synchronization between MS and BTS is provided by FCCH+SCH. The MS determines the frequency of the BCCH carrier by searching for the frequency correction Burst transmitted via FCCH;…
Physical Combination of Logical Channel in GSM
As shown above, CCCH=PCH+RACH+AGCH; downlink CCCH=PCH+AGCH; and uplink CCCH=RACH. In the above combinations, combination 3 and 4 must be allocated to slot 0 of the BCCH carrier configured for the cell; while combination 5 must be allocated to timeslots 2,…