GSM technology, GSM RF optimization, GSM Planning and How GSM Works.
Effect in Cell Coverage Area In coverage limited cells the frequency hopping may increase the cell coverage area because of the frequency diversity gain, but since the BCCH time slot doesn’t hop, the increased coverage area is relevant only for the ongoing calls that have been successfully established and are allocated a hopping TCH. According … Read more
Cyclic vs. Random Hopping Sequences Both cyclic and random hopping modes are available in GSM. In the cyclic mode the frequencies are changed sequentially from the lowest frequency to the highest as defined in the MA-list. In random mode the frequency to be used for each burst is selected from the MA-list by a predefined … Read more
Effect of Interleaving In GSM the speech frame is transmitted over eight consecutive bursts. The fast fading causes bursty bit errors that degrade the efficiency of the convolutional coding. The interleaving is designed to spread these errors over longer time. However, the decoding performance is not significantly improved if consecutive bursts are exposed to the … Read more
Work of MA, HSN and MAIO in GSM Mobile Allocation The MA is a list of hopping frequencies transmitted to a mobile every time it is assigned to a hopping physical channel. The MA-list is a subset of the CA list. The MA-list is automatically generated if the baseband hopping is used. If the network … Read more
The Cell Allocation (CA) is a list of all the frequencies allocated to a cell. The CA is transmitted regularly on the BCCH. Usually it is also included in the signaling messages that command the mobile to start using a frequency hopping logical channel. The cell allocation may be different for each cell. In GSM … Read more
The requirement that the BCCH TRX must transmit continuously in all the time slots sets strict limitations on how the frequency hopping can be realized in a cell. The current solutions are Baseband Frequency Hopping (BB FH) and Synthesized Frequency Hopping (RF FH). In the baseband frequency hopping the TRXs operates at fixed frequencies. Frequency … Read more
Slow and Fast Frequency Hopping in GSM Frequency hopping can be briefly defined as a sequential change of carrier frequency on the radio link between the mobile and the base station. In GSM, one carrier frequency is divided into eight time slots. Each time slot provides one physical channel, which can be assigned to one … Read more
When mobile has been selected successfully the mobile now will start reselection tasks. Perform Cell reselection measurement first Mobile will continuously make measurements on its neighboring cells (as indicated by the BA list) to initiate cell reselection if necessary. At least 5 measurement sample per neighboring cell is needed. A running average of the received … Read more
MOBILE IDLE When the mobile is idle, it listens to the best cell to camp. Mobile decides to choose the cell by itself without the help of BSC. This is done by comparing signal strength of each BCCH frequency and if found the strongest then it will camp once the C1 > 0 (Cell Selection … Read more
RxLevAccessMin Parameter is decide to allow mobile to access Network.its also used to reduce access on any BTS. RxLevAccessMin = Mobile Sensitivity + Body loss + Multipath loss + Interference Margin Mobile Sensitivity = -104 for GSM900 and -102 for DCS1800 Body loss : = 3 dB recommended by ETSI and 5 dB for GSM … Read more