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Cisco Employee

New implementation

Got a couple questions.

In using a AiroNet 350 with an Outdoor OmniDirectional (360 Degrees) Ant.

How many Clients Can I connect to the AiroNet 350 Unit? Is there a Limit?

Also, Can I use standard Client Cards with a External Ant. (Ie: The clients in the possible application are 500ft to 2.5 Miles away.)

What is my seperation between Int. reach Omnidirectional Outdoor Ant's need to be (ie: Multiple AiroNet Units at the same Location for Point-to-MultiPoint Applications.)

Is there any place I can Get very detailed information on the Ants. or a place within Cisco I can get more information on the product?

Thanks in advance!

Joe

11 REPLIES
Bronze
Cisco Employee

Re: New implementation

These documents did not help me Answer my original Questions. I need to know how many Clients a Single 340/350 Aironet unit can handle, and using an External Outdoor OmniDirectional Ant. What could my possible ranges be?

Please Advise,

-Joe

Bronze

Re: New implementation

The specifications section of these documents indicates: “Range Indoor: 150 ft at 11 Mbps (100 ft for 340 series only); 350 ft at 1 Mbps (300 ft for 340 series only) Outdoor: 800 ft at 11 Mbps (400 ft for 340 series only); 2000 ft at 1 Mbps (1500 ft for 340 series only)” but it’s not clear what external antenna they’re suggesting. I’ve read other posts that have said they are connecting hundreds of machines through one access point. It sounds like you’ll need a couple access points in your design as repeaters. I would think your Cisco SE engineer could help you design this.

New Member

Re: New implementation

Joe,

The type of antenna is really not relavent to the number of users you can have on a ap. Antenna is related to coverage area and signal strength in that area. What is related to number of users is how many macs a single ap can handle (don't quote me but I think it is 1024 addresses). But what you must really consider is total bandwidth that any user might have. Would you put 1024 users on a single 10 meg ethernet? probable not due to bandwidth contrants. so I would encourage you to base users on bandwidth requirements. I have done some large auditorium situations where I sectorized the antennas and used multiple ap's to get more bandwidth.

hope this helps.

terry

New Member

Re: New implementation

Hi Joe

the 340 AP can handle 2048 clients (based on the Hardware), so it's enough (11 Mbit/s / 2048 = 45kbit/s /client :-( radio thoughput )

Regarding you antenna question: Yes, that's possible, but unfortunately Cisco does not sell Antennas for "Hand-Helds", so for the PCMCIA Card, except the standard rubber duck.

But there are other vendors providing you with the necassary antennas up to 5dbi.

Rgds.

Andre

New Member

Re: New implementation

Actually, 11Mbps is the radio data rate--not the throughput. The throughput will be much different considering you are working with a half-duplex ethernet-style communication.

More like a max of 6Mbps divided by 2048. Then again, where did the 2048 come from?

The number of clients that you can connect is going to rely more on what kind of bandwidth needs you have and how many times you want to oversubscribe.

Tony

New Member

Re: New implementation

kwon47,

Your overall throughput assessment is accurate, however I would note that the 802.11 standards are not Ethernet-style. Ethernet (IEEE 802.3) is designed to function in a Carrier Sense Multiple Access / Collision Detection (CSMA/CD) configuration whereas the wireless solutions (802.11 a, b, and the forthcoming g) are all Carrier Sense Multiple Access / Collision Avoidance (CSMA/CA). This is important to note do to the high overhead involved with the collision avoidance function.

As for the 2048 number, that is the number of MAC addresses that a Aironet access point can support (based on the Cisco documentation, I doubt that will ever be tested though).

I would also point out that an Aironet access point will NOT provide coverage out 2.5 miles, even with the antennas designed for the bridges (which the 13dBi onmi is). The other limitation (beyond client antenna gain and transmit power limitations) is that the 802.11 standards are LINE OF SIGHT technologies when used outside over any distance greater than 1/4 mile. If you can not physically SEE the access point or bridge you can not communicate with it (that would have to be a very interesting environment; read - barren wasteleand; for a handheld device to work over 2.5 miles).

New Member

Re: New implementation

Cody,

I understand that 802.11 uses CSMA/CA, I just didn't want to have to explain how it all works.

Anyway, you can get farther than 2.5 miles from an access-point and still communicate. Using thrid-party sectorized antennaes and amplification, you can go over 12 miles on a point-to-multipoint install. I know because I've tested it.

Also, line of sight just means having no more than a certain percentage of obstruction in your first fresnel zone. It doesn't mean you have to be able to see the tower with the naked eye. How do you think point-to-point shots out to 25miles are done?

Tony

New Member

Re: New implementation

Tony,

Point taken on the CSMA/CA and the alignment of bridges @ 25 miles (although I didn't intend to infer the use of the naked eye, optics help quite a bit).

This might just be symantics, however, how do you get an access point to function over 2.5 miles? I thought that an access point would have too much slip in its timing after around a mile. The bridge units compensate for the increased latency, however the access points don't (or was I mislead?).

I was also wondering, what manufacturer do you use for sectorized antennas and who makes an FCC authorized amplifier?

Thanks,

Cody

New Member

Re: New implementation

Hi Kwon,

can You tell me what possible ranges can I get on the ISA-342 card with external antennas??

(eg. directional 24dbi, omni 14dbi etc.)

I wan to make a connection with my friend who lives 4km from me is it possible on this cards?

Can I use those adaptors a access point (put them into PC with LAN card)???

Thanx for help

xddj

New Member

Re: New implementation

The limit with standard clients is 1 mile. This is a timing issue in the 802.11 standard. Bridges modify these timers and can go farther, but are not technically 802.11 compliant. I can't stress enough, do a proper site survey, or have one done, and there will be no questions about coverage.

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