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…
Category: GSM
GSM technology, GSM RF optimization, GSM Planning and How GSM Works.
Uplink Logical Channel in GSM
1. Random access channel (RACH) It is an uplink channel used for MS randomly access to network by requesting for an SDCCH. The request includes a 3bit setup reason (call…
Logical Channel Type in GSM
As we know, every cell has several TRX and every TRX includes 8 timeslots (i.e. providing 8 basic physical channels). In the radio subsystem, the physical channel supports the logical…
Burst in GSM
The Logical Channel is used in time multiplex in a physical channel, which is categorized according to the types of messages transmitted in the physical channel. Different logical channels are…
Definition of Logical Channel in GSM
The physical channel is the medium over which the information is carried. The logical channel consists of the information carried over the physical channels. A Physical Channel (a TS, defined…
What is Frame and Channel in GSM
The major basic concept concerned with the radio path transmission of the GSM system is the burst sequence (simplified as Burst). It is a string of transmission units including more…
DTX: Discontinuous Transmission
Actually, during the communication process, the mobile subscriber talks only 40% of the time and there is not much useful information transmitted during rest of the time. If all the…
Frequency Hopping
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,…
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…
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….
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…
How Diagonal Interleaving for Data in GSM
To Improve Error Protection and Security of Data the Data is Interleaved and its type is Diagonal let’s check how it works. The diagram below illustrates, in a simplified form,…