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PROJECT REPORT ON HANDOVERS IN GSM. SUBMITTED BY :- Ankita Jain Tulika P rasad Vandana Bind Hemant Kumari Aishwarya Jain. GUIDED BY :- MR. SURESH DHRUWEY. GSM. Global System for Mobile Communications considered a second generation (2G) mobile phone system .
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PROJECT REPORT ON HANDOVERS IN GSM SUBMITTED BY:- AnkitaJain TulikaPrasad VandanaBind HemantKumari AishwaryaJain GUIDED BY:- MR. SURESH DHRUWEY
GSM • Global System for Mobile Communications • considered a second generation (2G) mobile phone system. • The GSM network is divided into three major systems: • the switching system (SS) • the base station system (BSS) • the operation and support system (OSS).
GSM NETWORK • The GSM network can be divided into following broad parts: • The Mobile Station(MS) • The Base Station Subsystem (BSS) • The Network Switching Subsystem (NSS) • The Operation Support Subsystem (OSS)
GSM ARCHITECTURE COMPONENTS • The added components of the GSM architecture include the functions of the databases and messaging systems: • Home Location Register (HLR) • Visitor Location Register (VLR) • Equipment Identity Register (EIR) • Authentication Center (AuC) • SMS Serving Center (SMS SC) • Gateway MSC (GMSC) • Chargeback Center (CBC) • Transcoder and Adaptation Unit (TRAU)
DESCRIPTION OF GSM SUBSYSTEM • THE MOBIE STATION (MS): - Mobile Equipment(ME) - Subscriber Identity Module(SIM) • BASE STATION SUBSYSTEM (BSS) - Base Transceiver Station(BTS) - Base Station Controller(BSC) • NETWORK SWITCHING SUBSYSTEM (NSS): • Mobile Switching Center (MSC) • Visitor Location Register (VLR)
HAND OVERS • Handover is a process in telecommunications and mobile communications in which a connected cellular call or a data session is transferred from one cell site (base station) to another without disconnecting the session. • It allows users to create data sessions or connect phone calls on the move.
PURPOSE OF HANDOVERS • when the phone is moving away from the area covered by one cell and entering the area covered by another cell . • when the capacity for connecting new calls of a given cell is used up . • in non-CDMA networks when the channel used by the phone becomes interfered by another phone using the same channel in a different cell.
again in non-CDMA networks when the user behaviourchanges. • in CDMA networks , a handover may be induced in order to reduce the interference to a smaller neighbouringcell .
TYPES OF HANDOVERS • Inter System Handoff: • A handover, in which the source and the target are different cells (even if they are on the same cell site). • The purpose of inter-cell handover is to maintain the call as the subscriber is moving out of the area covered by the source cell and entering the area of the target cell.
INTRA-CELL HANDOVER • A handover, in which the cell is not changed. • The purpose of intra-cell handover is to change one channel, which may be interfered or fading with a new clearer or less fading channel.
HARD HANDOVERS • The channel in the source cell is released and only then the channel in the target cell is engaged. • is perceived by network engineers as an event during the call. • intended to be instantaneous in order to minimize the disruption to the call. • break-before-make.
SOFT HANDOVER • The channel in the source cell is retained and used for a while in parallel with the channel in the target cell. • is perceived by network engineers as a state of the call, rather than a brief event. • Connections to three, four or more cells can be maintained by one phone at the same time. • make-before-break
IMPLEMENTATION • For the practical realisation of handoffs in a cellular network each cell is assigned a list of potential target cells. • They implement different algorithms and may use for input data from field measurements or computer predictions of radio wave propagation in the areas covered by the cells. • The downlink (forward link) and/or uplink (reverse link) directions may be monitored
In analog systems the parameters used as criteria for requesting a hard handover are usually the received signal power and the received signal-to-noise ratio. • In non-CDMA 2G digital systems the criteria for requesting hard handover may be based on estimates of the received signal power, bit error rate (BER) and block error/erasure rate (BLER), received quality of speech (RxQual), distance between the phone and the BTS (estimated from the radio signal propagation delay) and others. • In CDMA systems, 2G and 3G, the most common criterion for requesting a handover is Ec/Io ratio ( ratio of Received power of the carrier to the all over Noise)measured in the pilot channel (CPICH) and/or RSCP(Received Signal Code Power).