Archive for the ‘802.11n’ Tag
One of my Enterprise customers asked me today about 802.11ad as a replacement for their 802.11n, and if they should wait for chipsets that support operation in 60 GHz. Here’s what I wrote back:
“802.11ad / 60GHz technology is most likely going to be used for short-range / high-capacity cable replacement (think wireless HDMI to home theater components). The higher frequency doesn’t make it a candidate to replace the current use cases of today’s Wi-Fi. Also, because of that different frequency band, it will not be backward compatible with 802.11n or legacyWi-Fi (802.11 a/b/g). While there could ultimately be multiple chips in end-user / client devices, history suggests it’s not likely – most of the phone / tablet manufacturers today don’t implement chipsets for 2.4 GHz *and* 5 GHz largely due to battery life concerns. Additionally, similar claims around having multiple chips for both Wi-Fi and Wi-Max were popular at one time, but were never widely productized. ”
Today was the 2nd day in the CWAP (Certified Wireless Analysis Professional) beta course. Today’s material was a lot more hand-on / lab type exercise in capturing and analyzing traffic. From what I could tell, there were three main tools used by the course attendees:
They all seem to have their pros and cons, and they all seem to cost about the same amount of money (especially if you want to do multichannel packet capture on ~3 channels). Which tool do you prefer? Why?
The course contains an enormous amount of detail, such as the exact length (in microseconds) for slot times for each PHY type as well as a discussion on the application of that detail (i.e. how do the different slot times affect WLAN performance with and without QoS enabled).
Again, I thought one of the most valuable things were the networking opportunities with the other attendees and the sidebar conversations. A colleague (and good friend) of mine, Ken Hall, was even inspired to sign up for a Twitter account (@wifiscubaguy) to continue the interaction outside of this course / classroom. His account will definitely be on my next list of #WirelessWednesday mentions.
Tomorrow is the last day of the course. From what I know, we are covering a lot of 802.11n concepts, as well as spectrum analysis, which should be a blast.
I will be speaking at the Region One Technology Education Conference in South Padre Island, TX tomorrow at 9 AM local time.
My presentation is titled “802.11n: Lessons Learned from the First 1,000 Xirrus Installations”
Districts making the move to 802.11n or deploying a wireless network for the first time will explore lessons learned from the past two years of over 1000 Xirrus 11n installations. Site surveys, network design, client considerations, performance results, interoperability and backwards compatibility will all be investigated.
Leadership and Administration – e-Rate Training and Technology Purchasing
Innovation – Web 2.0 Tools, Mobile Devices and Open Source Products
Teaching and Learning – Technology Education and Content Area Based Workshops
Technology Support and Management – Security, Data Management and Green Technologies
Here is a link to the conference website: http://www.esc1.net/129310101014405833/site/default.asp
The Burton Group and Xirrus are offering a FREE educational webinar today (Wednesday, Dec 2nd) on the newly ratified IEEE wireless standard, 802.11n. I delivered the Xirrus portion of this presentation at INTEROP New York a couple weeks ago, so I can tell you it’s packed with great information. 🙂
“802.11n: Lessons Learned from the First 1,000 Xirrus Installations”
Date: Wednesday, December 2, 2009
Time: 11:00 am PT / 2:00 pm ET / 7:00 pm UK
Paul DeBeasi, Senior Analyst, Burton Group
Kurt Sauter, Director of Product Marketing, Xirrus
The webinar is posted on the Xirrus webinars page: http://www.xirrus.com/library/webinars.php
You can use the below to register:
This webinar will discuss:
• Features that the first generation 11n products provide
• Site Survey Issues
• Performance Expectations
• Network and Architecture Considerations
• Client Device Considerations
• Security Issues
• Overall Recommendations
The webinar will be archived on the Xirrus website, and anyone will be able to listen/view after the live event.
This is a guest post that originally appeared on CWNP.com – the post generated a LOT of comments, so I thought I would pull it out of “the valut” and re-publish here at WiFiJedi.com
I recently ran a poll on my blog (WiFiJedi.com) about frequency band utilization for 802.11n deployments. Here are the results:
In what frequency band do you plan to deploy 802.11n?
- 2.4 GHz = 17%
- 5 GHz = 12%
- Both (2.4 GHz and 5 GHz) = 18%
- Not sure – why does it matter? = 8%
- No plans to deploy 802.11n = 45%
Personally, I found the results surprising for two reasons. First, I was surprised by the large number of respondents who said they have no plans to deploy 802.11n. I wonder what factors are keeping them from deploying 802.11n? Price? Security? Reliability? Scalability?
Second, I was surprised by the low number of respondents who chose a pure 5 GHz 802.11n deployment. I believe there are numerous advantages to deploying WLANs in the 5 GHz band, especially when it comes to 802.11n.
Consider the following:
Number of Available Channels
There are only three non-overlapping channels in the 2.4 GHz frequency band. Channels 1, 6, and 11. There are 23 non-overlapping channels between the 5GHz lower, middle, and upper bands.
Because there are many more non-overlapping channels in the 5 GHz range, it can deliver greater total capacity. 802.11g networks offer 54 Mbps of capacity on each of the three non-overlapping channels in the 2.4 GHz spectrum. This equates to a total capacity of 162 Mbps. 802.11a has the same speed, 54 Mbps, but offers a total of 1.24 Gbps of capacity across its 23 non-overlapping channels. This holds true for 802.11n networks as well. With speeds of 150 Mbps per channel, there are 450 Mbps of 802.11n capacity with 2.4 GHz use and 3.45 Gbps of capacity with 5 GHz use.
The 2.4 GHz frequency band is crowded with interfering devices. Other Wi-Fi access points, microwave ovens, cordless phones, Bluetooth devices, baby monitors, etc. all make for a noisy environment. This degrades the overall signal-to-noise ratio (SNR). The 5 GHz band is considerably cleaner in most areas – see for yourself with a spectrum analyzer!
With nearly 8 times the number of channels to chose from in the 5 GHz band, planning is far simpler than in the 2.4 GHz band. I realize that most enterprise grade solutions have some sort of auto-channel or automatic radio management feature to assist with this, but co-channel interference remains a concern, especially in tight spaces or high-density environments. The additional choices in 5 GHz minimizes the possibility that two APs will utilize the same channel in the same areas.
Sure, some organizations need to support legacy devices in the 2.4 GHz spectrum. However, I don’t think it makes sense to deploy 802.11n networks in this band. One of the main technical improvements available in 802.11n is channel bonding. There is only space for one bonded channel in the 2.4 GHz band which, if utilized, would increase the probability of co-channel interference and make channel planning even more complex.
Last week, at the Gartner Mobile & Wireless Summit in Chicago, Michael King and Timothy Zimmerman gave a presentation on Next-Gen WLANs. In their presentation, they said that 802.11n networks are faster, cheaper, more secure, more reliable, and better managed than the wired infrastructure deployed in most enterprises today. Additionally, they said enterprises should align networking investments to an all-wireless office. I agree with them. But to maximize your chance of success, do it in 5 GHz.
There was no public outrage for the lack of a “Super Tuesday Poll” on WiFiJedi.com last week.
However, as “they” say… the show must go on. Here is this week’s poll:
Yesterday, I attended a webinar hosted by AirMagnet entitled “Optimize Your 802.11n Performance”.
It was an hour well spent, which isn’t always the case with webinars. The product sales pitch was kept to a minimum.
It really focused on educational aspects of 802.11n networking and security. Additionally, the webinar contained several live demos during the webinar, which were executed flawlessly.
The live demos were of the WiFi Analyzer and Survey programs. While I use the AirMagnet Survey product several times a week, it has been almost a year since I used the AirMagnet WiFi Anlyzer tool. They have instituted some really great features since I have last used it. Most of these features directly relate to 802.11n networks:
The first is an 802.11n Device Throughput Calculator. It calculates the throughput of a single device depending on a number of parameters – MCS, max frame size, channel bonding, block acknowledgement, etc. It also factors in the effect of the Least Common Denominator client (i.e. effect of adding an 802.11g client).
The second is a WLAN Throughput Simulator, which estimates the aggregate throughput of an entire WLAN. The tool takes actual meaurements from the existing WLAN, and then allows users to add simulated APs or Clients. This allows users to consider an infinite number of “what if” scenarios with regards to how to optimize the WLAN.
The webinar wasn’t limited to exploration of the cool features of the WiFi Analyzer. A good portion of the presentation talked about the importance of live/active site surveys and how using real meaurements of the uplink and downlink rates is valueable to network administrators. It was also exciting to see that the iPerf throughput testing tool is now integrated directly into AirMagnet Survey.
Lastly, I wanted to point out that one of the five main points of the webinar was that channel bonding in 2.4 GHz is not suggested. This is something that I blogged about in a post regarding 5 GHz vs. 2.4 GHz in 802.11n networks on CWNP.com I seemed to take a decent amount of “heat” in the comments, primarily from advocates of channel blankets, so I am glad to see that the fine folks at AirMagnet agreed with me. 🙂
Welcome CWNP.com readers! I hope you enjoyed my guest blog post at http://www.cwnp.com regarding frequency band utilization for 802.11n networks.
Since you’re here, I am guessing that you interested in wireless networking and security!
Below are a some of my most popular blog posts to-date:
- Frequency Band Utilization for 802.11n Networks
- Replacing Desktop Ethernet With Wireless
- IEEE Ratification of 802.11n Standard
For Project Managers
My 802.11n How Stuff Works Series was so popular, I thought I would start another series. This time I am going to talk about the various deployment considerations for 802.11n networks, such as:
- Trobleshooting/Analysis Tools
- WIDS/WIPS Sensors
Let’s take a look at the first of these considerations, cabling. With 802.11n, the data rates are drastically improved. Rates can be as high as 600 Mbps, but most practical implementations of 802.11n today have data rates of approximately 300 Mbps.
Therefore, the cable used should have higher capacity than 10/100 Mbps. What cables have 1 Gbps cabability? Category 5e or Category 6 cables can support the neccessary speed for 802.11n networks. IEEE 802.3ab also specifies 1000-Base-T over Category 5 cables, although I would personally recommend Cat 5e or Cat 6 cable.
Many newer access points or arrays have multiple physical interfaces to include console ports, 10/100 out of band management ports, and one or more 10/100 or Gigabit uplink ports. If your access points or arrays support multiple uplink ports, you should run separate cables to each.
Many times the multiple uplink ports can be configured in several different “modes” to include daisy chaining, port failover, port mirroring, or 802.3ad link aggregation. In port failover mode, running multiple uplink cables gives you a level of redundancy to survive a single port failure on either the access point or the uplink switch, increasing the overall reliability of the system.
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