Structure Of An Iwlan - Siemens SIMATIC NET System Manual

Basics of communication with Industrial Ethernet
1.5 Wireless LAN
1.5.9

Structure of an IWLAN

Basic structure of a WLAN
WLANs do not have a physical topology like traditional wired networks. There are no
"buses", "rings" or "stars". Instead wireless networks are divided into cells.
Figure 1-3 Simple WLAN structure with two access points/wireless cells, RCoax cable and IWLAN/PB Link PN IO
gateway
Here, access points take over the role of switches. End nodes are connected to the network
by turning on "clients". Larger networks can be achieved by setting up several wireless cells
each under the control of an access point. The connection between individual cells is also
via access points.
The access points function as their own wireless cell, between which the mobile nodes can
move. ("roaming")
Shared medium instead of switched medium
Wireless networks operate on the shared medium principle, in other words, only one node
can send at any one time. With the increasing number of nodes, the effective data rate that
can be reached by the individual nodes sinks.
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System Manual, 09/2019, C79000-G8976-C242-10
Industrial Ethernet