23-07-2012, 03:54 PM
HANDOFF STRATEGIES
67 HANDOFF STRATEGIES O.pptx (Size: 181.96 KB / Downloads: 39)
WIRELESS COMMUNICATION
Wireless is a term used to describe communications in which electromagnetic waves carry the signal over part or all of the communication path.
Why Wireless communication Is Needed?
To span the communication beyond the capabilities of cable.
To overcome the obstacles such as physical structure, EMI.
To provide backup links when network fails.
THE CELLULAR CONCEPT
Segmentation of the area into cells.
Deals with replacing a single high powered transmitter with many low powered transmitters.
Channels are divided among the base stations.
Use of several carrier frequencies.
Same frequency is not used in adjoining cells.
If a mobile user changes cells the handover of the connection to the neighboring cell takes place.
THE SHAPE OF THE CELL
There are 3 criteria for selecting a cell shape:
1. The geometric shape
2. Area without overlap
3. Area of the cell
A hexagon, square, equilateral triangle can be fitted in a manner where there is no area of overlap unlike circle.
Also a hexagon has the largest area after circle.
Thus of the lot hexagon satisfies all the conditions which is why the shape of a cell is hexagonal in cellular network.
FREQUENCY REUSE
The design process of selecting and allocating channel groups for all of the cellular base stations within a system is called FREQUENCY REUSE.
The N cells which collectively use the complete set of available frequencies is called a CLUSTER.
Cells with same the same letters use the same set of frequencies.
A cell cluster is put together and replicated over the coverage area.
TYPES OF HANDOFF
HARD HANDOFF:
1. existing connection is broken before new one is established.
2.The break is short enough to remain unnoticed by the user .
3. Categorized into inter-cellular and intra-cellular hard handoffs.
SOFT HANDOFF:
1. Breaking of connection not required.
2. New connection is made before the old one is broken.
SOFTER HANDOFF:
1. New signal is added or deleted from the active set of signals.
2. Also occur when a signal is replaced by a stronger signal from a different sector under the same base station.
67 HANDOFF STRATEGIES O.pptx (Size: 181.96 KB / Downloads: 39)
WIRELESS COMMUNICATION
Wireless is a term used to describe communications in which electromagnetic waves carry the signal over part or all of the communication path.
Why Wireless communication Is Needed?
To span the communication beyond the capabilities of cable.
To overcome the obstacles such as physical structure, EMI.
To provide backup links when network fails.
THE CELLULAR CONCEPT
Segmentation of the area into cells.
Deals with replacing a single high powered transmitter with many low powered transmitters.
Channels are divided among the base stations.
Use of several carrier frequencies.
Same frequency is not used in adjoining cells.
If a mobile user changes cells the handover of the connection to the neighboring cell takes place.
THE SHAPE OF THE CELL
There are 3 criteria for selecting a cell shape:
1. The geometric shape
2. Area without overlap
3. Area of the cell
A hexagon, square, equilateral triangle can be fitted in a manner where there is no area of overlap unlike circle.
Also a hexagon has the largest area after circle.
Thus of the lot hexagon satisfies all the conditions which is why the shape of a cell is hexagonal in cellular network.
FREQUENCY REUSE
The design process of selecting and allocating channel groups for all of the cellular base stations within a system is called FREQUENCY REUSE.
The N cells which collectively use the complete set of available frequencies is called a CLUSTER.
Cells with same the same letters use the same set of frequencies.
A cell cluster is put together and replicated over the coverage area.
TYPES OF HANDOFF
HARD HANDOFF:
1. existing connection is broken before new one is established.
2.The break is short enough to remain unnoticed by the user .
3. Categorized into inter-cellular and intra-cellular hard handoffs.
SOFT HANDOFF:
1. Breaking of connection not required.
2. New connection is made before the old one is broken.
SOFTER HANDOFF:
1. New signal is added or deleted from the active set of signals.
2. Also occur when a signal is replaced by a stronger signal from a different sector under the same base station.