Optimization

Optimization

  • Submitted By: sushilo
  • Date Submitted: 03/12/2013 11:00 PM
  • Category: Book Reports
  • Words: 742
  • Page: 3
  • Views: 149

GSM Frequency Spectrum

GSM 900
■ DL: 935-960 MHz, UL: 890-915 MHz
■ 200 kHz channel spacing ( 124 channels
■ ARFCN 1 – 124
E-GSM
■ DL: 925-935 MHz, UL: 880-890 MHz
■ 200 kHz channel spacing ( Additional 50 channels
■ ARFCN 0, 975 - 1023
GSM 1800
■ DL: 1805-1880 MHz, UL: 1710-1785 MHz
■ 200 kHz channel spacing ( 374 channels
■ ARFCN 512 – 885
UMTS Band I

1920-1980 and 2110-2170 MHz

Frequency Division Duplex (FDD, W-CDMA) Paired uplink and downlink,

Channel spacing is 5 MHz

Raster is 200 kHz.

Carrier frequencies are designated by a UTRA Absolute Radio Frequency Channel Number (UARFCN)

UARFCN = 5 * (carrier frequency in MHz)

e.g 1st carrier frequency is 1922.4 MHz (5 MHz – 200 kHz/2)

UL: 9612 to 9888
DL: 10562 to 10838



What is frequency reuse?

As the GSM spectrum is limited, frequencies have to be reused to provide enough capacity

Aim: Minimizing the frequency reuse for providing more capacity

But: More frequencies on air ( higher interference


Reuse Cluster

Group of cells which do not reuse the same frequency (or frequency group) are said to belong to a ‘reuse cluster’

Reuse Cluster Size – RCS


Used if no of TRX per cell is the same.


Average Reuse Cluster Size – ARCS



Used by calculating average no of TRX per cell.

Tradeoff


The lower the ARCS is:


■ the higher is capacity traffic (more TRX/cell)
■ The higher interference is

Traffic capacity/inference is always a trade-off.

Example 1

BCCH reuse is always RCS, because we don’t need to use an average (always one BCCH per cell).

Sectorized sites
4 sites per reuse cluster
3 cells per site

REUSE Cluster Size:
4X3 =12

Example 2

Another example of BCCH RCS

Sectorized sites
3 sites per reuse...

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