2012/02/16

CHOOSING THE RIGHT 11N - from Qualcomm

Extract From: http://www.qca.qualcomm.com/technology/feature.php?feature=5


The good news: the 802.11n specification offers a lot of different configurations from 1- to 4-stream options, operation in either or both the 2.4 and 5 GHz bands, and a variety of optional features like spatial multiplexing and 40 MHz mode.

The bad news: while choice is great, the array of options makes it difficult for customers to choose the right combination of features for their products and for consumers to select for their personal use.
As a leading developer of 11n solutions, Qualcomm Atheros suggests the following considerations when selecting the right combination of 11n features for our customers’ products and their end users’ selection.
  •  What applications with what bandwidth requirements will the product support? Simple data functions like email, web browsing and downloading YouTube files or high-definition videos and playing high-resolution video games?
  • Where will the product be used most often? Home? Office? On the go?
  • Will interference from other devices— household products like microwaves and baby monitors— be an issue?
  • How many other Wi-Fi®-enabled devices will operate in the product’s environment and compete for the available wireless spectrum?
  • Will the device need to connect at long range (more than 100 feet from the router or other devices in the network) or not?
  • What is the desired price range of the product?

Here are some rules of thumb that we’ve devised to help our customers make the important feature decisions for 11n.

More streams equals more bandwidth.
Each stream offers up to 150 Mbps PHY rate of bandwidth. Currently, Qualcomm Atheros offers solutions in 1-, 2- and 3-stream configurations. While a 4-stream configuration could yield up to a 600 Mbps PHY rate, we currently do not envision a commercially viable 4-stream option that provides greater real-world performance than 3-stream.

The greater the number of streams, the greater the rate-over-range.
        Typically, what matters most in Wi-Fi products and networks is the usable rate-over-range, because RoR is the amount of bandwidth that’s available at connection points within the user’s environment. The greater the RoR, the greater the coverage of the home, office or at mobile locations like hotspots.

2.4 GHz, 5 GHz or Both?
2.4 GHz is a narrow, relatively crowded band of 3 non-overlapping wireless channels
  •         Good for data functions like email, browsing, data file transfers, standard definition video applications like YouTube, audio transfers, low-res gaming
  • Good in environments relatively free of interfering devices such as microwave ovens and baby monitors
5 GHz is a wide, clean band of 24 non-overlapping channels
  •         Good for functions that require no/low latency such as HD video, real-time, high-resolution video gaming
  •         Better for environments fraught with interference from other networks and household devices
Dual-concurrent, dual-band
  •         Today’s networks and consumer electronics products increasingly employ the best of both worlds with dual-concurrent 2.4 and 5 GHz, offering 27 aggregate unduplicated wireless channels that enable network management, allocating the 2.4 GHz band for data-centric applications and 5 GHz for multimedia
It’s all about the app
The applications that will be handled by a router, consumer electronics device or computer have a big impact on which 11n is needed. Here are some apps-based suggestions for applicability of a particular 11n solution.

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