design wlan
Post on 03-Jan-2016
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Design WLAN
Politeknik Telkom 2008
Design WLAN
Step to design WLAN :1. Location Survey2. Topology3. Distance calculating4. Antenna design5. Towering6. Power calculation7. Radio choosing
Location survey
Tools :Spectrum analyzerGPSMapLaptopNetstumbler (www.netstumbler.com)
Netstumbler
Coverage area vs number acces point
AP = C Total
C(AP)
dimana :
AP : Number of Access Point
C(AP) : coverage area of AP (maximum power)
C Total : total of coverage area
Antenna design
Parameter of antenna quality :ImpedanceSWRGainS/N
Antenna design
Software :
MMANA-GAL
http://mmhamsoft.amateur-radio.ca/
MMANA-GAL
MMANA-GAL vertical lobe
MMANA-GAL horisontal lobe
MMANA-GAL impedance vs frequency
MMANA-GAL SWR vs frequency
Towering
Model of tower :
Power calculation
Power calculation
Parameter of power calculation :RX signal level (dBm)Free Space Loss (dB)SOM (dB)
Power calculation
Input parameter Free Space Loss :Frequency (MHz)Distance
Power calculation
Input parameter Rx Signal Level :TX Power (dBm)TX Cable Loss (dB)TX Antena Gain (dBi)Free Space Loss (FSL)RX Antena Gain (dBi)RX Cable Loss (dB
Power calculation
Input parameter SOM :Rx signal levelRx sensitivity
Power calculation
Example : Frequency = 2,45 GHz Distance between 2 station = 16 miles TX Power = 9,9 dBm TX Cable Loss = 5,1 dB TX Antena Gain = 24 dBi RX Antena Gain = 20 dBi RX Cable Loss = 3 dB RX Sensitivity = 15 dBm
Power calculation
Calculate :
a. Free Space Loss
b. Rx Signal level
c. SOM (System Operating Margin)
Reuse frequency
EIRP
EIRP (Effective Isotropic Radiated Power)
EIRP (dBm) = TX Power (dBm) – TX Cable Loss (dB) + TX Antena Gain (dBi)
EIRP
TX Power
Power Gain / Loss
Resulting
Power
Antenna gain
Resulting EIRP
Legal ?
1 Watt(+30 dBm)
-1 dB loss via 1 m coax
+ 29 dBm
+6 dBi
+35 dBm
Yes
100 mW(+20 dBm)
+14 dB Amplifier
+34 dBm
+8 dBi
+42 dBm
No
25 mW(+14 dBm)
+14 dB Amplifier
+28 dBm
+8 dBi
+36 dBm
Yes
EIRP
Example :
A directional antenna 24 dBi has EIRP 36 dBm, cable loss 3 dB. Tx Power?
EIRP
Answer :
EIRP (dBm)= TX Power (dBm) – TX Cable Loss (dB) + TX Antena Gain (dBi)
36 = TX (dBm) – 3 + 24
TX (dBm) = 36+3-24 = 15 dBm = 30 mW
Channel of Wifi IEEE 802.11b
Channel ID
Channel Frekuensi F(t) MHz
Alokasi Frekuensi Tiap Pancar (MHz)
F(t )- 11MHzF(t) + 11
MHz
1 2412 2401 2423
2 2417 2406 2428
3 2422 2411 2433
4 2427 2416 2438
5 2432 2421 2443
6 2437 2426 2448
7 2442 2431 2453
Channel of Wifi IEEE 802.11b
8 2447 2436 2458
9 2452 2441 2463
10 2457 2446 2468
11 2462 2451 2473
12 2467 2456 2478
13 2472 2461 2483
14 2477 2466 2488
WiFi 802.11b
Modulation : DSSSWidth of spectrum : 22 MHz
802.11b spectrum
Overlapping channel
Overlapping channel
3 non overlapping channel :Channel 1 = 2412 MHzChannel 6 = 2437 MHzChannel 11 = 2462 MHz
Overlapping channel
4 non overlapping channel :Channel 1 = 2412 MHzChannel 5 = 2432 MHzChannel 9 = 2452 MHzChannel 13 = 2472 MHz
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