Cisco Cisco Aironet 1140 Access Point 디자인 가이드
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Cisco 1140 Series Access Point Deployment Guide
OL-18384-01
So, What Exactly Is 11n?
(and resultant latency) as more voice handsets are introduced to a legacy cell. Such limitations erode
with 11n. The media access layer of 802.11n offers more reliability-even to legacy 11a/b/g
devices-thanks to the benefits from the physical layer enhancements, multiple antennas, and support for
additional spatial streams that come from 11n's new radio technology. All this results in transmissions
getting where they need to go the first time they're sent. Cisco tests show that, with both 11n and legacy
11a/b/g clients, 802.11 re-transmissions are reduced by half on Cisco’s 802.11n Access Points compared
to legacy transmissions on legacy access points.
with 11n. The media access layer of 802.11n offers more reliability-even to legacy 11a/b/g
devices-thanks to the benefits from the physical layer enhancements, multiple antennas, and support for
additional spatial streams that come from 11n's new radio technology. All this results in transmissions
getting where they need to go the first time they're sent. Cisco tests show that, with both 11n and legacy
11a/b/g clients, 802.11 re-transmissions are reduced by half on Cisco’s 802.11n Access Points compared
to legacy transmissions on legacy access points.
Note
In this document, the term "legacy" refers to all devices that do not support the high throughput rates of
802.11n. This includes all clients and access points that support 802.11, 802.11b, 802.11g, and 802.11a
PHY types.
802.11n. This includes all clients and access points that support 802.11, 802.11b, 802.11g, and 802.11a
PHY types.
The ability to provide reliable connectivity consistently across the entire network is an integral part of
the radio enhancements of 802.11n. This consistent reliability across time and motion, even in places not
before reachable (due to nulls, signal muddling, and other negative effects of multipath), means that 11n
finally brings predictability to the Wi-Fi world. In-house testing shows that the Aironet 1140 Series
access point reduces variation in client latencies and retries by half.
the radio enhancements of 802.11n. This consistent reliability across time and motion, even in places not
before reachable (due to nulls, signal muddling, and other negative effects of multipath), means that 11n
finally brings predictability to the Wi-Fi world. In-house testing shows that the Aironet 1140 Series
access point reduces variation in client latencies and retries by half.
So, What Exactly Is 11n?
802.11n comprises a number of features that come together to give the spec its increased performance,
reliability, and predictability. Put basically, these gains are achieved via radio enhancements, MIMO
antenna technology, and enhancements to the 802.11 MAC.
reliability, and predictability. Put basically, these gains are achieved via radio enhancements, MIMO
antenna technology, and enhancements to the 802.11 MAC.
Radio Enhancements
There are two important parts to the PHY (physical layer) augmentations of 802.11n that give the new
standard the ability to deliver better raw data rates and, thus, higher application speeds. Both parts are
conceptually straightforward. The most obvious enhancement is that the new 802.11n PHY supports
much faster data rates, along with support for legacy 802.11a/b/g speeds. The 11n PHY actually supports
a very wide array of different speeds, called modulation coding scheme (MCS) rates.
standard the ability to deliver better raw data rates and, thus, higher application speeds. Both parts are
conceptually straightforward. The most obvious enhancement is that the new 802.11n PHY supports
much faster data rates, along with support for legacy 802.11a/b/g speeds. The 11n PHY actually supports
a very wide array of different speeds, called modulation coding scheme (MCS) rates.