Siemens SIMATIC NET System Manual page 54

Basics of communication with Industrial Ethernet
1.5 Wireless LAN
The IEEE 802.11 group
Under the project number "802", a number of working groups were given the task of
developing standards for setting up and operating networks. A known example is the "802.3"
working group that is concerned with the standards for Ethernet connections.
The "802.11" working group concentrates on the specification for wireless LAN, the IEEE
802.11 standard. The most important extensions of the standard are 802.11b, 802.11g,
802.11n, 802.11ac and 802.11ax.
"802.11" standards
The following table provides an overview of the features of the individual standards:
802.11a/h
Year of Introduction 1999
Frequency band 5 GHz
Bandwidth 20
Gross data rate 54 Mbps
Modulation proce- OFDM
dure
Transmission sys- SISO
tem
Max. number of 1x1
antennas on sender
and receiver end
DSSS - direct sequence spread spectrum
OFDM - orthogonal frequency-division multiplex
SC-OFDM - single carrier orthogonal frequency-division multiplex
OFDMA - orthogonal frequency-division multiple access
SISO - Single Input Single Output
MIMO - Multiple Input Multiple Output
SU-MIMO - Single-User MIMO
MU-MIMO - Multi-User MIMO
Expansions of the 802.11 standard include the following:
● 802.11 "e": Introduces QoS to provide better support for real-time applications (VoIP,
streaming),
● 802.11 "i": Replaces the no longer tenable WEP encryption mechanism with WPA or
WPA2.
● 802.11 "p": Introduces WLAN technology for motor vehicles with which an interface for
applications involving intelligent traffic systems is created.
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802.11b 802.11g
1999 2003
2.4 GHz 2.4 GHz
20 20
Max. 54 Mbps
11 Mbps
DSSS OFDM
SISO SISO
1x1 1x1
802.11n 802.11ac
2009 2013
2.4 GHz + 5 5 GHz
GHz
20 / 40 40 / 80 / 160
600 Mbps 1733 Mbps (max.
6.93 Gbps)
OFDM SC-OFDM
SU-MIMO MU-MIMO (down-
link)
4x4 8x8
System Manual, 09/2019, C79000-G8976-C242-10
802.11ax
2019
2.4 GHz + 5 GHz
80 / 160
19.2 Gbps
SC-OFDMA
MU-MIMO (down-
link und uplink)
4x4
Industrial Ethernet