AiroNet 1140 slow Wireless Speed Issue

[beny]

Hi There,

We are having some issues at our site (20 users) which has a 50mbps downstream and 50mbps upstream fiber connection. When connected to the wireless (Cisco AiroNet 1140 WAP). The wireless speed is only 15-20mbps Max. When connected via Lan cable the speed is around 45mbps. The office size is reasonably large. We are looking at solutions to increase the wireless speed so that it is as fast as a LAN cable and we can utilize the fiber connection properly.

A potential solution we are looking at is to mount the existing Cisco AiroNet 1140 to the ceiling at 1 end of the office and then mount another Cisco AirNet 1140 to the ceiling near the other end of the Office. I was wondering if the second Cisco AiroNet should be setup as a Root Bridge or what kind of Briding Setup to use? Also, do you think this will allow us to utilize the full speed of our fiber connection or would you recommend another WAP altogether? 

Bridging the 1140 information: 

http://www.cisco.com/c/en/us/td/docs/wireless/access_point/12-4_21a_JA1/configuration/guide/scg12421aJA1.pdf

[Scott Fella]

Wired and wireless are two different beast... you will never get wireless to be as fast as wired.  Wrieless is half duplex so if your connected at 54mbps, then max you can see if half, around 27mbps.  Other variables that affect this is air quality, channel utilization and how many clients.  Your gigabit ethernet on the AP is also your bottle neck if you have too many users.... 25 users per AP is a rule of thumb but not set in stone.  I would not use a root bridge approach... I would just cable a new run to another AP location and place another AP in the area.

[Rasika Nayanajith]

The wireless speed is only 15-20mbps Max. When connected via Lan cable the speed is around 45mbps.

As scott said, you are getting this speed due to the half duplex nature of wireless. If your AP model is 1142, then you can configure radio1 interface (5GHz)  for the SSID. You MUST use WPA2/AES  or Open Auth in order to get 802.11n speeds which is greater than 54Mbps. I do not think you are using that at the moment & it may be a reason why clients data rates not get 802.11n speeds.

Below shows different AP model max data rates. If your clients having multiple spatical stream (SS) capability they can get higher speeds. Note that 20MHz BW is the max you can get in 2.4GHz band & 40MHz bandwidth you can get from 5GHz with channel bonding. So 5GHz is always better if you looking for higher througput (but obviously client should able to connect in 5GHz)

Adding antoher AP would be a good idea (without bridging) & see wether you could afford 2602 or 3602 which can go upto 450Mbps data rates . Practically if you could you get 50% (which is around 200Mbps) that is really good. Note that this is total AP througput & if you connect multiple clients that will be shared among users.

Also keep in mind when you add multiple users all users aggregate bandwidth is limited to 50Mbps due to your WAN link speed. So that would be the bottleneck within your network.

HTH

Rasika

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[beny]

Thanks a lot for your help responses. I did notice the Cisco Aironet 1140 Series is configured for both 2.4ghz and 5ghz. There is some screen captures from the router settings interface shown in the attached pictures. What setting changes would you suggest here?

[Leo Laohoo]

Disable 802.11b data rates of 1, 2,  5.5 and 11 Mbps.  

Make 18 Mbps as Mandatory and from 12 Mbps and up as Supported.