Cellular Systems Cellular Concepts The cellular concept was a ...

EE5401 Cellular Mobile Communications
EE5401 Cellular Mobile Communications
R
R
R
2
2
2
Atri = 1.3R
Asq
= 2.0R
Ahex
= 2.6R
• Interference tier : A set of co-channel cells at the same
distance from the reference cell is called an
interference tier. The set of closest co-channel cells is
call the first tier. There is always 6 co-channel cells in
the first tier.
• Hence, a conventional cellular layout is often defined
by a uniform grid of regular hexagons.
Frequency reuse :
• A cellular system which has a total of S duplex
channels.
• S channels are divided among N cells, with each cell
uses unique and disjoint channels.
• If each cell is allocated a group of k channels, then
S = kN .
Co-ordinates for hexagonal cellular geometry
• With these co-ordinates, an array of cells can be laid
out so that the center of every cell falls on a point
specified by a pair of integer co-ordinates.
Terminology
• Cluster size : The N cells which collectively use the
complete set of available frequency is called the
cluster size.
• Co-channel cell : The set of cells using the same set of
frequencies as the target cell.
If ( ∆ u , ∆v)
= ( i,
j)
, i,j are known as the shift
parameters, then the distance between the two cell
centres is given by
2
2
D = i + j + ij ⋅ 3R
(Cosine’s Rule)
Institute for Infocomm Research 45 National University of Singapore
Institute for Infocomm Research 46 National University of Singapore