Design WLAN Politeknik Telkom 2008

Design WLAN Step to design WLAN : 1. Location Survey 2. Topology 3. Distance calculating 4. Antenna design 5. Towering 6. Power calculation 7. Radio choosing

Location survey Tools : Spectrum analyzer GPS Map Laptop Netstumbler (

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 : Impedance SWR Gain S/N

Antenna design Software : MMANA-GAL

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

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 level Rx 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 Result ing Power Anten na gain Resulti ng EIRP Lega l ? 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) – TX (dBm) = = 15 dBm = 30 mW

Channel of Wifi IEEE b Channel ID Channel Frekuensi F(t) MHz Alokasi Frekuensi Tiap Pancar (MHz) F(t )- 11MHzF(t) + 11 MHz

Channel of Wifi IEEE b

WiFi b Modulation : DSSS Width of spectrum : 22 MHz

802.11b spectrum

Overlapping channel

3 non overlapping channel : Channel 1 = 2412 MHz Channel 6 = 2437 MHz Channel 11 = 2462 MHz

Overlapping channel 4 non overlapping channel : Channel 1 = 2412 MHz Channel 5 = 2432 MHz Channel 9 = 2452 MHz Channel 13 = 2472 MHz