802.11n Unlocks the Potential of the 5 GHz Band - Page 2

 By Ken Biba
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The Test Setup

To make the comparison, we selected a few standard 802.11g clients (The same clients we use for the Novarum Wireless Broadband Review of metropolitan wireless networks), several after-market 2.4 GHz 802.11n clients, a classic 802.11g access point, the new Apple dual-band draft 802.11n clients (embedded in Intel based MacBooks) and the new dual-band Airport Extreme N access point.

Our testing location is a classic San Francisco Victorian house with four floors and many small rooms. To illustrate the effects of wall and floor penetration, we picked seven locations of gradually increasing distance and numbers of walls and floors between the access point and the client test location. This residence has always needed several 802.11g 2.4 GHz access points to provide adequate Wi-Fi coverage. We used our standard Chariot delay, upstream throughput, downstream throughput test scripts from the Novarum Wireless Broadband Review to capture the data in a consistent fashion.

Throughput Comparison
802.11n and g compared
(click to open in a new window)

The Results

The pure 802.11n 5 GHz connections (between Apple's MacBook and Airport Extreme access point) had at least three times the throughput of the legacy 802.11g system in all but one location (where all systems performed equally). 802.11n in the 5 GHz band also delivered twice the throughput of 802.11n in the 2.4 GHz band in these tests.

These tests, while not exhaustive, illustrate the potential of 802.11n in the 5 GHz band. The extended range provided by 802.11n overcomes many of the real world deployment challenges of 5 GHz 802.11a networks. Novarum testing of Draft 802.11n products shows that 802.11n operating at 5 GHz will have similar range to legacy 802.11g networks in the 2.4 GHz band—at the maximum data rates.

The combined performance benefits of 802.11n enable more practical enterprise deployments at 5 GHz. The result is that 802.11n will be able to operate effectively across many more channels and therefore deliver much higher capacity in a given area.

Deployment strategies

While some have proposed that 802.11n will allow enterprise networks to operate with fewer APs, we think a better deployment strategy is to use the same AP density as current 802.11g networks but operate the entire 802.11n network in the 5 GHz band. Legacy 802.11 b/g clients and guest network access should stay in the 2.4 GHz band served by legacy APs or new 802.11n APs operating in legacy mode. With legacy 802.11 a/b/g clients and unknown guest clients isolated in the 2.4 GHz band, the 802.11n network at 5 GHz can operate at the highest possible performance. Our testing shows that the range and coverage of 802.11n will be sufficient to deliver maximum data rates across an enterprise with the access point density that we expect from 802.11g networks.

802.11n will accelerate the transition of wireless LANs from the 2.4 GHz band to the 5 GHz band, and users will benefit from the additional capacity that is available at 5 GHz.

Article courtesy of Wi-Fi Planet

This article was originally published on Aug 18, 2007
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