gsm
Once the mobile is switched on and the registered home PLMN was selected (e.x. SMART), it will next search for a BCCH frequency list, stored in its memory or in its SIM card. The list can have up to 32 BCCH frequencies for the mobile to scan. This reduces the time of cell selection, compared … Read more
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 utilizes the RF hopping, the MA-lists have to … 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
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
Location-Aided Handover (LAH) Algorithm is actually a set of algorithms, which aims to solve the current handover procedure problems. The set of algorithms include current handover algorithm, fuzzy handover, handover algorithm based on the use of adaptive antennas, handover prioritization algorithm, etc. LAH is based on the CELLO Architecture, which is shown below: This figure clearly shows … Read more
Handover is the mechanism that transfers an ongoing call from one cell to another as a user moves through the coverage area of a cellular system. The number of cell boundary crossings increases because smaller cells are deployed in order to meet the demands for increased capacity. If we minimize the expected number of handovers … Read more
Both the power control and the DTX are standard GSM features, which are designed to minimize the interfering transmission when possible. They are both mandatory features in the mobile terminals, but it is up to the network operator to decide whether to use them or not. DTX prevents unnecessary transmissions when there is no need … Read more
In a conventional non-hopping network, each call is transmitted on a single fixed frequency. This means that the interference situation in a network is also quite stable. Some calls may experience very little interference and the other calls may be interfered severely. Severe interference can be avoided by a handover, but the probability of finding … Read more
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