HP Radio Frequency Planner Software Series - Manual (Page 118)

Appendix D: Glossary of Terms
HP RF Planner User Guide
116
Term Definition Description
multiple radios. The maximum number of spatial streams is limited
by min (n, m), that is, the minimum among the number of radio
chains at the transmitter and receiver. IEEE 802.11n draft 2.0
makes it mandatory for APs to support a minimum of two spatial
streams and support for up to four streams optionally.
Channel width
Legacy 802.11 protocols operate on 20 MHz channels. IEEE 802.11n
allows bonding of two 20 MHz channels so that a net channel width
of 40 MHz can be used. In 40 MHz mode, one channel is assigned as
the “primary” channel and the other is assigned as the “secondary”
channel. The secondary channel is identified as “upper” or “lower”
with respect to the primary channel. For example, in 2.4 GHz, if
channel 6 is the primary channel then channel 10 could be assigned
as the upper secondary and channel 2 as the lower secondary
channel.
Guard Interval (GI)
The guard interval is the spacing between consecutive symbol
transmissions. IEEE 802.11n draft 2.0 prescribes a mandatory long
Guard Interval of 800 ns and an optional short Guard Interval of 400
ns.
MCS
Modulation and Coding
Schemes
IEEE 802.11n draft 2.0 defines 77 MCS based on the modulation
technique, coding rate, number of spatial streams, channel width,
and guard interval. The mandatory settings of 20 MHz channel
width, 800 ns guard interval, and up to two spatial streams gives a
total of 16 mandatory schemes (MCS 0 to 15).
Frame aggregation
Frame aggregation is introduced in IEEE 802.11n for improving the
protocol efficiency. Aggregation is defined at two levels: Medium
Access Control (MAC) and physical (PHY) layers. At the MAC layer,
Multiple MAC Service Data Units (MSDUs) or subframes are
aggregated and an aggregated MSDU (A-MSDU) is delivered to the
PHY layer for transmission. The maximum A-MSDU size can be set
to 4KB or 8KB; the maximum MSDU size carried in each subframe is
limited to 2304 bytes. At the PHY layer, Multiple Protocol Data Units
(MPDUs) or subframes can be aggregated into an aggregated MPDU
(A-MPDU). The maximum size of an A-MPDU is 64 KB or 64
subframes, whichever limit is reached first. The maximum MPDU
size carried in each subframe of an A-MPDU is limited to 4065 bytes.
Regulatory Domain
Compliance
Different countries have regulatory agencies permitting a select
number of channels for device protocols. Therefore, the power
values of the devices placed on the floor map will operate only on
those power values that match that of the respective country where
you are planning.
While specifying the desired power range for each protocol, ensure
that the values are complaint with the regulatory domain for a
particular country for which you are performing planning.
If you create a .spm file in one location and forget to send the
device information along with the .spm to another location, then the
Client at the second location will not be able to view the device
information of the previous location. In such a case, Planner assigns
the default device, as defined by you, in the .spm. If this device has
power values conflicting with the regulatory domain compliance of
the region, then Planner assigns the factory default device, which is
regulatory domain complaint for any region.