INTERLINE company, leading Polish microwave antenna producer, set itself a goal to check possibility of establishing a wireless link in 2.4 GHz band with direct sequence spread spectrum DSSS (802.11 b standard) at a range currently being only a subject theoretical dispute.
The aim of the enterprise was a practical assessment of possibilities and study of phenomenas concerning such a link.
It should be stressed that the link built is typical ground link and that diversivies it from the one built at the end of 2002 by Swedish company Alvarion and Swedish Space Corporation, which used a stratospheric baloon.
What is equally important, all elements used in the INTERLINE experiment are off-the-shelf, unmodified equipment available comercially (1.1 meter parabolic antenna and a 500 mW amplifier). Swedish experimentators used 2.4 m parabolic antenna and a 6000 mW amplifier.
Two localisations were chosen for the link: Wroclaw (a city) and a Hala pod Sniezka (Sniezka is a highiest mountain of Karkonosze), S-W from Jelenia Gora.
The distance is around 110 km.
In the experiment actively participated:
- Piotr Kroplewski - owner of the INTERLINE
- Wiesaw Karpowicz - Manufacturing Manager
- Maciej Kaminski - Technical Division Manager
- Krzysztof Mularczyk - Wireless Network Specialist
- Krzysztof Juszczyszyn - Manufacturing Technologist
One of a key stages of the experiment was a choice of localisations for stations which were to create a point-to-point link. First of them is a 11 stage house on a one of Wroclaw's districts.
Second one, key to the experiment, is a glade by the summit of Sniezka, nerby Dom Slaski shelter (1400 meters above sea level)
For the experiment following equipment was chosen:
- Antenas - PARABOLIC maxi, 27 dBi - product of INTERLINE
- Access points - INTEL Pro/Wireless 2011 Access Point - made by SYBMOL
- Cables and connectors - cables BELDEN H-1000, H-155, RG-316, connectors VITELEC
- Wireless cards - Lucent ORiNOCO PC Card Silver/chipset Agere, ZCom XI-300/chipset Intersil
- aMPLIFIER - TONZE 2.4 GHz, 500 mW
Of course there were also 2 laptops. Additionally we had: UPS, a set of tools, spare cables, connectors and a gas solder (just in case).
Remote end-point: Wroclaw
As the date of the experiment was set a time between 12th and 14th of September 2003.
First stage was mounting and directing an antena in Wroclaw to point towards nieka mountain. Due to good visibility in Wroclaw in the day of installation (2003.09.12), this mountain, which is 1602 meters above sea level, was clearly visible. During the directioning vertical angle was important, due to the fact, that the other end of the link was 1400 meters above sea level.
1. Access Point
INTEL Pro/Wireless 2011 Access Point + Amplifier 2.4GHz/500 mW
- Channel: 5 (2432 MHz)
- Net_ID: wisznia
- Hardware Revision: A
- AP Firmware Ver.: 02.52-13
- RF Firmware Ver.: V2.51-08
- Radio Type: T2
- Antenna Selection: Primary Only
RF Configuration .DTIM Interval 10 WLAP Mode Enabled .BC/MC Q Max 10 .Max Retries (d) 32 WLAP Priority 8000 hex .Max Retries (v) 5 WLAP Manual BSS ID 00:02:B3:15:2F:55 .Multicast Mask (d) 09000E00 hex .Multicast Mask (v) 01005E00 hex WLAP Hello Time 20 .Beacon Interval 100 K-us WLAP Max Age 100 .Accept Broadcast ESSID Enabled WLAP Forward Delay 5 .MU Inactivity Timeout 60 min. WLAP MU Table Aging Time 240 min. .Rate Control 11 Mb/s Not Used .Shared Key Disabled 5.5 Mb/s Not Used .Key Width 40 bit 2 Mb/s Not Used .Encryption Key ID 1 1 Mb/s Required Encryption Key Maintenance .RTS Threshold 2347 bytes BlueTooth Coexistence 0 ms .Short RF Preamble Disabled Extended Range 50 mi. Tx Power Control Full
2. Antena cable
- cable type: BELDEN H-1000
- length: 5 meters
- connectors: type N
- cable type: BELDEN H-155
- length 30 cm (0.3 m)
- connectors: type N and RP-BNC
Installation - Karkonosze mountains, Kopa-Sniezka
On 14th September 2003 all the equipment has been transported with OPEL Frontiera (we had obtained permission of the Karkonosze National Park authorities) to the meadow near the Sniezka's summit.
On the installation place weather was as usually in the mountains. Almost all the time the place was covered by clouds. Only from time to time for a dozen seconds wind split the clouds and we were offered splendid views of surrounding mountains.
Proficient team quickly installed PARABOLIC maxi antena on the portable mast. Due to dense clouds we could not direct antena by just looking towards Wroclaw. The best direction was eventually found and everything was set.
The Belden H-155 cable (3m long) was connected to antena with a N plug.
Than other equipment could be connected: cards, access points, amplifier.
2.4 GHz band was scanned to detect alien/foreing signals. We used ZCom XI-300 card and a WiLAN Expert software.
We did not find any significant signals in the whole 2412-2483 MHz range.
Stage 1: one way signal detection
Operation mode: 802.11b Infrastructure
- Wireless card: Lucent ORiNOCO PC Card
- Connector: INTERLINE N/MCCARD
Stage 2: two way data communication
Measurements were done with NetStumbler v. 0.3.30 software.
While correcting antena's settings we have discovered 1 (one) foreign net (pol-czaj) on channel 1, but the signal level was very low and noice was significant.
With a great joy this pleasent to our ears sound (listen) let us know, that we have received a beacon frame from the transmitter in Wroclaw.
Establishment of a link
Reception of a beacon frame, while an unmistanken success, did not mean we had established a two-way connection.
The basic form of such a connection was a trial to transmit via ICMP an ECHO command with a PING programm. (We are sorry for the picture quality - it was taken in field conditions)
Stage 3: two way data transmission
Operation mode: WLAP - Wireless LAN AP - bridge mode for INTEL PRO/Wireless 2011 Access Point
- access point: INTEL PRO/Wireless 2011 Access Point
- pigtail: INTERLINE N ... RP-BNC
Measurement done during a Telnet session from INTEL shown signal at a level RSS=8, that means roughly 20% of the maximum throughput. That allowed to establish an WLAP connection with negotiated speed of 1Mbps. The connection was being broken every dozen of seconds. This could be caused by several conditions, which are being analysed by our company.
To stabilise the link between antena and the access point we have used 2.4 GHz/500mW amplifier. RSS increased to RSS=28, which meant about 80% of the maximum.
Having available such a good link we have moved to the main point - FTP file transfer from an FTP server in Wroclaw. At this moment we did not know, what is the actual speed we can send data at. The logging to the server went very quickly. We have chosen the file, chosen to get one, and... the SUSTAINED 40kB/s +/- 4kB/s (kilo Bytes per second). That's almost 0.5 Mbps, wireless, over 110 km distance.
Most probably we witnessed first transmission of such a great amount of data via a wireless link in 2.4 GHz band with a comercially available Wi-Fi equipment.
We do our best to make INTERLINE equipments even better, we broaden our knowledge to be able to help you to succeed in your enterprises.
And now ... watch the movie!
Thank you for your attention and best regards to all customers of INTERLINE.
Piotr Kroplewski, Wieslaw Karpowicz, Maciej Kaminski, Krzysztof Mularczyk