Concept Of Handover Or Handoff Inwards Gsm/2G As Well As 3G

Handover or Handoff

Today inward this article nosotros volition larn virtually Handovers in addition to why it is required.
Actually, Hanover's or handoff are required for continuous mobility or connectivity thence that agency whenever nosotros are moving nosotros don't involve telephone band breakdown or connexion breakdown. For this the requirement nosotros get got a concept of handover. So allow dive inward it.

Let nosotros get got 2 telephone prison theatre cellular telephone every bit shown inward the icon above. At the border of the cell, the character of the dot is non practiced every bit compared to the electrical current position of the user. As the user moves towards the border of prison theatre cellular telephone the dot gets weaker in addition to the user starts sending mr (measurement report). Measurement written report tells that I am going to a pitiable network area, delight mitt over me to roughly other cell.
Now thence the user volition live transferred to a novel prison theatre cellular telephone in addition to good gets starting improve coverage. So the procedure of shifting a user telephone band command from pitiable network surface area to novel prison theatre cellular telephone is known every bit Handover or Handoff.
That's why handover or handoff is required for seamless mobility.

Home in addition to Foreign cell

allow suppose if nosotros are moving inward an surface area inward which nosotros get got a let out of cells connected for event prison theatre cellular telephone A, B, C, D, eastward every bit shown inward in a higher house minute image.
The user where He/She commencement a telephone band is known every bit the domicile prison theatre cellular telephone in addition to the coming adjacent prison theatre cellular telephone is called the unusual cell. After the handover procedure when the user shift to prison theatre cellular telephone B thence prison theatre cellular telephone B is the domicile prison theatre cellular telephone for the user in addition to coming adjacent prison theatre cellular telephone C volition regard the foreign cell in addition to thence on. This procedure volition proceed until the user reaches to prison theatre cellular telephone E.

Types of Handover

There is 2 type handoff

• Soft Handover
• Hard Handover

Hard Handover used inward GSM (Global organization for mobile communication) besides known every bit 2G. The procedure is " Break earlier brand " this agency earlier the user makes a connexion alongside the foreign cell y'all must suspension a connexion alongside the domicile cell.

Soft handover procedure is contrary to Hard handover. The procedure is "Make earlier break" this agency that earlier breaking the connexion alongside the domicile prison theatre cellular telephone it volition brand connections alongside unusual prison theatre cellular telephone thence it volition suspension the connexion alongside the domicile cell. It is used inward 3G.

The Handover procedure is farther categorized into Vertical handoff in addition to Horizontal handoff.

The Vertical handoff is differ from Horizontal handoff due to the next reasons:

1. Not solely 1 type of network connexion is introduce rather, to a greater extent than than 1 network connexion is introduce inward Vertical handoff.
2. RAT is changed inward Vertical handoff.
3. Not solely RAT is changed, QoS in addition to that of network interface may live changed inward Vertical handoff.
4. The IP address is changed inward both Vertical in addition to Horizontal handoff.

Vertical Handover Process:

The procedure of Vertical handover is categorized into 4 dissimilar stages:

1. Handover Initialization stage.
2. System regain stage.
3. Decision making stage.
4. Handover execution stage

1. Handover Initialization Stage:

The procedure is initiated yesteryear 1 or to a greater extent than than 1 network pick parameters.
Checks for link character or decrease inward dot strength.

2. System Discovery Stage:

In organization regain phase the mobile terminal collect all the information virtually the available networks inward social club to select network for handover. QoS tin live used to telephone commutation information betwixt the mobile in addition to the network.

3. Decision Making Stage:

In this phase of determination making, the Vertical handover create upwards one's withdraw heed whether to proceed the connexion alongside the electrical current network or to switch to the previous one. The pick in addition to the determination depends on the bandwidth, availability, frequency etc of the network.

4. Handover Execution Stage:

In this lastly phase of Handover execution stage, when the determination has made, the connections are re-routed from the source network to the target network. It involves the transfer of signals along alongside authorisation in addition to authentication.

Vertical Handover Classification:

Vertical handover is farther classified into 4 (4) categories:

1. Depending on management
2. Depending on process
3. Depending on direction
4. Depending on control

1. Depending on direction: (Upward & Downward)

When a mobile user switches from a network alongside depression surface area coverage to the network alongside high surface area coverage, thence the handover is called upward handover in addition to when the mobile user switches from network alongside high surface area coverage to the network alongside lower surface area coverage, thence this type of handover is called downward handover.

2. Depending on process: (Hard & Soft)

when the mobile user breaks the connexion alongside the electrical current network earlier establishing connexion alongside the novel network , this type of handover is called difficult handover every bit speak over above. And when the mobile user connects alongside the novel network later on that breaks connexion alongside the previous network, this type of handover is called soft handover.

3. Depending on decision: (Imperative & Alternative)

When the value of RSS (Received Signal Strength) decreases the value of threshold, the handover is called imperative handover, Where every bit inward choice several handover parameters are taken into consideration such every bit bandwidth etc.

4. Depending on control: (Mobile & Network)

Simply it tin live defined that handover is controlled yesteryear the mobile node inward mobile controlled in addition to land that inward network-controlled, a key entity is responsible for controlling handover.

Advantages of handover or handoff

• Simultaneous connectivity agency fewer chances of telephone band suspension upwards due to weak signal.

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