Cisco Aironet 2702i AIR-CAP2702I-E-K9 Folheto
Códigos do produto
AIR-CAP2702I-E-K9
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Table 3.
Primary Ingredients of 802.11ac
Parameter
802.11ac Draft 3.0
Wave 1 Wi-Fi Alliance Certification
802.11ac (subset of ratified
amendment)
amendment)
Potential Wave 2 Wi-Fi Alliance
Certification
Certification
802.11ac Complete
Amendment
Amendment
Spectrum
5 GHz (varied support by regulatory domain; nearly 600 MHz in the
United States)
United States)
<6 GHz, excluding 2.4 GHz
Bandwidth
Mandatory: 20, 40, and 80 MHz
Mandatory: 20, 40, and 80 MHz
Optional: 160 and 80+80 MHz
Modulation
Mandatory: BPSK, QPSK, 16QAM, 64QAM
Optional: 256QAM
Number of spatial streams
Mandatory: 2 (nonmobile APs
*
),
1 (others)
Optional: up to 3 spatial streams
Mandatory: 2 (nonmobile APs
*
),
1 (others)
Optional: up to 4 spatial streams
Mandatory: 1
Optional: 2 to 8
Forward error correction
Mandatory: BCC
Optional: LDPC
STBC
Optional: 2×1 AP to client
Optional: 2×1, 4×2, 6×3, 8×4
Short guard interval
Optional
Sounding (a single interoperable
protocol)
protocol)
Optional
CTS in response to RTS with
bandwidth indication
bandwidth indication
Mandatory
RTS with bandwidth indication
Optional
Aggregation
Mandatory: TX and RX of A-MPDU
Optional: RX A-MPDU of A-MSDU
Mandatory: TX and RX of A-
MPDU
MPDU
Optional: RX A-MPDU of A-
MSDU
MSDU
A-MDPU, A-MDPU of A-
MSDU
MSDU
MU-MIMO
-
Optional
*
Additional requirement introduced by the Wi-Fi Alliance.
Because of the wider channel bandwidths of 802.11ac, it is much more likely that an 80-MHz AP will overlap with
another 20- or 40-MHz AP - and similarly an 80- or 160-MHz AP - or even several of them, all potentially on
different channels. To enable reliable operation amid this complexity, 802.11ac mandates extensions to the
RTS/CTS mechanism, stronger clear-channel assessment (CCA) requirements, and new primary channel selection
rules. See
802.11ac also introduces a valuable new technology called multiuser MIMO. This is challenging to get right, so it is
deferred until the second wave of 802.11ac products and will likely be optional. More on this later in
2.3.2 Differences Between 802.11ac and 802.11n
802.11ac has avoided the battles of 802.11n and instead has focused on extending the tremendous advances
made in 802.11n to deliver the next generation of speed and robustness.
For instance, 802.11n pioneered aggregation through the selective use of A-MPDU, A-MSDU, and A-MPDU of
A-MSDU (see the Appendix). 802.11ac actually requires every 802.11ac transmission to be sent as an A-MPDU
aggregate. This is due in part to the intrinsic efficiency of A-MPDU, as well as to some other factors (see
In a further example, 802.11ac extends the 802.11n channel access mechanism: virtual carrier sense and backoff
occur on a single 20-MHz primary channel; CCA is then used for the remaining 20-MHz subchannels immediately
before transmitting on them.