Wireless communication in the areas of difficult propagation conditions

Krzysztof Wierny

Radiotechnika Marketing LTD.

Military University of Technology

AFCEA's International Student Conference "Students at Work!"

STORCZYK Communication System

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COTS technology Military applications

1. System EXDWN from Xacta (USA)•Portable access point or bridge•IEEE 802.11 b, g, 54Mb/s, 2.4GHz•Omni and directional antennas both on the mast•security WPA-TKIP,EAP MAC

2.System Battle LAN S-WiFi from Thales•Access point or bridge for using on the vehicles•IEEE802.11b,g; 2-6 GHz,•Output power 1W•Range 1 km in open area (11Mb/s)

3.System TELCOR MeshCom from Telefunken•Access point or bridge •IEEE 802.11 b,g; 2,4 Ghz;•(1-10GHz ),range 300-1500m

COTS technology Military applications

Radiotechnika Marketing LTD. WLANBOX-Bridge 1-2,4

military communication systems requirements

• short deploying time and establishing communication,

• precluding easy localization and detection of communication node

• transmission range big enough to enable dispersion of shelters in the large area

• operation in military frequency bands.

Commercial communications wireless systems:

ADVANTAGES:• provides wide range available bit rates from 1 Mbit/s to

54 Mbit/s,• provides greater flexibility in network construction,• enables transfer modern data transmission technologies

and security mechanisms on military area .DISADVANTAGES:• WLAN have insufficient communication range • operating in commercially available, unlicensed

frequency bands, crowd of users• restricted transmitters power,• need precise positioning of directional aerials in bridge

connections

• output power 4W• bandwidth converter from 2,4Ghz to

1,6Ghz• system is placed in small portable box• operation up to 5 hours from the battery• connection with communication shelters

through the PKS and PKŚ cables• optical indicators of signal level for easy

alignment antennas

WLANBOX-Bridge operational parameters

System on measuring position

WLANBOX-Bridge

• 2 pcs of WLANBOX-BRIDGE 1-2.4 modules

• 2 omnidirectional antennas 12dBi on frequency band 2,4 GHz

• 2 directional antennas 24dBi on frequency band 2,4 GHz

• 2 tripad folding masts at 4m high

• 6m long antennas feed coaxial cables

• 2 pcs.of military notebooks with Pentium M processor.

Measurements - variable parameters

• Signal Strength

• Reliability of data transfers during transmission of 10 Mbytes long files.

• Error rate

• average effective data rate.

Measurements result

Antenna type

freq./output power

Directional 1,6GHz, 4W

Directional 2,4GHz, 30mW

Omnidirectional

2,4GHz, 30mW

max. distance between antennas

800m 220m 130m

transfer rate 500kb/s 300kb/s 250kb/s

error rate 10% 12% 16%

signal strength 22% 18% 18%

reliability Rarely interrupted

often interrupted transfer

often interrupted transfer

distance between antennas

600m 150m ~100m

transfer rate 2Mb/s 1Mb/s 1Mb/s

error rate 1% 3% 3%

signal strength 42% 40% 40%

reliability Stable transfer Stable transfer Stable transfer

Conclusions

• Propagation of waves in microwave bands in forests limited because of strong suppression caused by branches, leaves and trunks of trees

• Range of omnidirectional antennas is insufficient in dense forests area and can used with satisfaction for military application only at distance up to 100m.

• Using of amplifier with 4W output power brought in an increase of signal range of about four times

• Duration of antennas positioning is much longer for directional antennas than omnidirectional

Implementation of wireless WLANBOX Bridge system for military application.

1.wireless bridge can improve connecting remote command post (placed in building, tent) with communication shelter.

Implementation……cd

2. Connection between vehicles in motion

Implementation……

3. Communication on difficult area

Thank you very much for your attention