CELL SECTORING
description
Transcript of CELL SECTORING
CELL SECTORINGPREPARED BY: MUHAMMAD TALHA ISLAM
SECTION C2010-TE-054
TELECOMMUNICATION ENGINEERING DEPARTMENT
2
3
4
Sectoringcell splitting keeps D / R unchanged
(same cluster size and CCI) but increases frequency reuse/area
alternate way to ↑ capacity is to _____ CCI (increase S / I ratio)
5
replace omni-directional antennas at base station with several directional antennas3 sectors → 3 120° antennas6 sectors → 6 60° antennas
6
cell channels broken down into sectored groups
CCI reduced because only some of neighboring co-channel cells radiate energy in direction of main cell
center cell labeled "5" has all co-channel cells illustrated
only 2 co-channel cells will interfere if all are using 120° sectoring
only 1 co-channel cell would interfere when using 60° sectoring
If the S/I was 17 dB for N = 7 and n = 4, what is the S / I now with 120° sectoring? 24.2 dB
7
8
How is capacity increased?sectoring only improves S/I which increases voice
quality, beyond what is really necessaryby reducing CCI, the cell system designer can choose
smaller cluster size (N ↓) for acceptable voice qualitysmaller N → greater frequency reuse → larger system
capacity
What would the system capacity, Cnew, now be when 120° using sectoring, as compared to the old capacity, Cold ?
9
Example
10
SOLUTION
11
PROS AND CONSmuch less costly than cell splitting
only require more antennas @ base station vs. multiple new base stations for cell splitting
primary disadvantage is that the available channels in a cell are subdivided into sectored groupstrunked channel pool ↓, therefore trunking
efficiency ↓There are more channels per cell, because of
smaller cluster sizes, but those channels are broken into sectors.
12
other disadvantages:must design network coverage with sectoring
decided in advancecan’t effectively use sectoring to increase
capacity after setting cluster size Ncan’t be used to gradually expand capacity as
traffic ↑ like cell splittingMore HandoffsMore antenna, more cost
JAZAKALLAH