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CELL SECTORING

CELL SECTORING. PREPARED BY: MUHAMMAD TALHA ISLAM SECTION C 2010-TE-054 TELECOMMUNICATION ENGINEERING DEPARTMENT. Sectoring cell splitting keeps D / R unchanged (same cluster size and CCI) but increases frequency reuse/area

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CELL SECTORING

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  1. CELL SECTORING PREPARED BY: MUHAMMAD TALHA ISLAM SECTION C 2010-TE-054 TELECOMMUNICATION ENGINEERING DEPARTMENT

  2. Sectoring • cell 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)

  3. replace omni-directional antennas at base station with several directional antennas • 3 sectors → 3 120° antennas • 6 sectors → 6 60° antennas

  4. 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

  5. How is capacity increased? • sectoring only improves S/I which increases voice quality, beyond what is really necessary • by reducing CCI, the cell system designer can choose smaller cluster size (N ↓) for acceptable voice quality • smaller 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?

  6. Example

  7. SOLUTION

  8. PROS AND CONS • much 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 groups • trunked channel pool ↓, therefore trunking efficiency ↓ • There are more channels per cell, because of smaller cluster sizes, but those channels are broken into sectors.

  9. other disadvantages: • must design network coverage with sectoring decided in advance • can’t effectively use sectoring to increase capacity after setting cluster size N • can’t be used to gradually expand capacity as traffic ↑ like cell splitting • More Handoffs • More antenna, more cost

  10. JAZAKALLAH

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