Site Survey/WLAN questions

[admin_2]

All,

Does anyone have any websites or information regarding Wireless LAN site survey? Follows is what we are trying to do.

Several business customers wish to have high-speed internet, and they are more then the 12,000 feet from the Phone Center, so DSL is not an option. The terrain is generally flat with cedar trees and a few farms (mostly wheat and corn) in between. Our main office is 4.5 miles from the site that needs the access. They currently have dial-up, but when sharing across a network, it is extremely slow (of course.) Our office building is, unfortunately, in the middle of a bowl. The elevation at our office site is 1,160 ft ASL (above sea level), while the site we are trying to reach is at 1,340 ft ASL. The straight line distance is 4.51 miles. We can defeat some of our line-of-sight problems by putting a bridge (not sure if that is the right term, or maybe relay site is better) at our church which is situated on a hill behind our store. (They also would like the high-speed.) We have LOS to the church, and the church has a general LOS to the location that needs the access. The church is situated at 1,379 ft ASL. The gear I am planning on using is listed below. I am planning on using external antennas and/or directional antennas, but am unsure what type to use. The range is fairly long although the equipment says it can handle the distance.

Hopefully someone can see possible problems that might arise and/or have suggestions. If they wanna contact me direct, send to jstaley@certainty.net

Equipment Info:

Each PC will connect to an Wireless AP (not sure what type, possible go same vendor {Alvarion}, which will in turn connect to the BreezeNET RB-DS.11D

RADIO Frequency Range 2.4 - 2.4835 GHz ISM band (ETSI, FCC)

Radio Type Direct Sequence Spread Spectrum (DSSS)

Wireless LAN Standards Compliant with IEEE 802.11b HR

Selectable sub Channels FCC 1-11

Output Power FCC -4, -2, 4, 6, 12, 14, (dBm)

(at the antenna port) 20, 24

Sensitivity (BER 1E10-6) Data Rate Sensitivity Modulation

11 Mbps -85 dBm 256 CCK

5.5 Mbps -88 dBm 16 CCK

2 Mbps -90 dBm DQPSK

1 Mbps -93 dBm DBPSK

Processing Gain 10.4 dB Nominal

RANGE

US FCC Up to 25 km (15 miles)

SECURITY

Authentication and Data Encryption 40-bit RC4 WEP

The 2 BreezeNET RB-DS.11b will connect to the BreezeNET BU-DS.11D, which will be located at the main office where our T-1 lines connect.

RADIO Frequency Range 2.4 - 2.4835 GHz ISM band (ETSI, FCC)

Radio Type Direct Sequence Spread Spectrum (DSSS)

Wireless LAN Standards Compliant with IEEE 802.11b HR

Selectable sub Channels FCC 1-11

Output Power FCC -4, -2, 4, 6, 12, 14, (dBm)

(at the antenna port) 20, 24

Sensitivity (BER 1E10-6) Data Rate Sensitivity Modulation

11 Mbps -85 dBm 256 CCK

5.5 Mbps -88 dBm 16 CCK

2 Mbps -90 dBm DQPSK

1 Mbps -93 dBm DBPSK

Processing Gain 10.4 dB Nominal

RANGE

US FCC Up to 25 km (15 miles)

[#2]

Also, if anyone has any suggestions for better equipment, let me know. I use Alvarion because thats what we used while deployed to Iraq.

Joshua Staley

[ashish_gupta]

hi

for building to buiding you have to go for bridges and for internal u can go for WLAN cisco bridges are fairly robust equipments but you can also look for a radio like "WIPLL" by airspan which has very small lateral bandwidth and thus helps in tackling interference issues. Also u can also go point to multipoint links for your sites but for that the sites should be either within 90 degree or 120 degree coverage area depending on what sectorial antenna you use.

regarding wireless LAN survey u should make sure that bandwidth per user, signal at every place or practically where there are users, etc etc.

aasheesh

[#4]

Another question, the more research I do, I am liking the Cisco Aironet 1400 Series Wireless Bridges alot. Any suggestions or ideas on how this would work, using the above information. Also, if I am reading this literature correctly, I am wanting a point-to-multipoint setup. I want to use the 2nd bridge, at the church as a non root node, but my question is, do these setups have 2 antenna's or are they one antena, and if only one antenna, how good is an omni-driectional antenna over 4-5 mile ranges? I am looking to try and get at least 10Mbps aggregate bandwidth, since we will have multiple clients along the signal path.

Thanks all,

Joshua Staley

[thisisshanky]

Usually at the hub site (church in your case) the bridge would use omni directional antennas.

Use this tool to select the bridge and antenna type.

http://www.cisco.com/warp/public/cc/pd/witc/ao340ap/prodlit/obrc_in.xls

You can find out how far apart you can place the antennas/bridges for a particular bandwidth (say 11 Mps) that you desire to acheive.

[ashish_gupta]

hi

omni directional antennas have limited range and also have a limited gain. for bridges u can set u r clients to non root configuration. however one thing u should note that even then also u dont get a bandwidth of 10Mbps per client.

Also the Wipll that i was mentioning has a SPR which is mounted on the mast(or whatever) without any external antenna if the range is limited but u can use it if range is more.

[zappolinom]

I would use 2 pair of Aiornet 350 Bridges with attached Yagis or Parabolic Dish. The 2 Bridges on the Curch will then be linked back to back via Ethernet. Select two different Channels for each pair of Bridge different SSID and let the Bridges on the Curh be the Root Bridge for their correspondent pair.

A list of HW could be follwing:

4xAIR-BR350-A-K9

4xAIR-ACC3354 Lightning Arrestor with grounding ring

4xAIR-ANT1949 13.5 dBi Yagi Mast Mount Ant.

4xAIR-ACC2662 Antenna Mount for Yagi ANT1949

or alternatively

4xAIR-ANT3338 21 dBi Solid Dish Antenna

in addition you need up to for all 4 Antennas a Antenna Cable with the required length.

To calculate exact distances youse the Antenna Calc Tool which is downloadable for Partners.