My simple Network topology

Im trying to figure out what the maximum speed is in mbps on the blue and red links. The exact specs of the wireless networks are these:

  • IEEE 802.11b/g/n, 2.4GHz

Dual omnidirectional internal antennas, 2T2R, 2.8dBi peak gain

  • IEEE 802.15.4, 2.4GHz IPv6

Omnidirectional internal antenna, 2.8dBi peak gain

A) According to this site Speed of IEEE 802.15.4 The max speed of the 802.15.4 standard is 250 Kbit/s. Is that the correct number i am looking for regarding this standard?

B) If the blue links in my topology (connection between Gateway & Access Point) instead of wireless was connected with cable would that then mean that it would have the same max. speed as the gateway (which has a 4g Sim of 50 Mbps in it) ?

C) I just can't find the maximum for the 802.11 standard itself. I can only find the speed of the specific versions ie. 802.11b,g,n etc. My teacher told me those versions were irrelevant since they are device related bottleneck. I am looking for the network speed related bottleneck in general of 802.11.

Hope you guys understand my question.

  • 1
    There is no such thing as "speed of 802.11 in general" It depends on the particular data rate and encoding method, which is specified in subsections a, b, g, n – Ron Trunk Dec 16 '19 at 21:01

A) Yes, 802.15.4 has a max. link rate of 250 kbit/s; can't say much about possible effective rates though.

B) Using wired Ethernet 100BASE-TX or 1000BASE-T would support a maximum, effective link speed of 100 Mbit/s or 1 Gbit/s respectively for a maximum of 100 m link reach. It seems overkill for 250 kbit/s edge devices but you won't ever get any congestion between the gateway and the 802.15.4 APs.

C) 802.11g supports a maximum link rate of 54 Mbit/s, 802.11n of 450 Mbits (depending on the WAP, 150 Mbit/s and 300 Mbit/s are also common). The effective speed is about 50% of that in the best case. Note that in your scenario that speed is shared across all APs, so there's some likelihood of congestion.

| improve this answer | |
  • 802.11n operating as specified in 2.4GHz (unless run as Greenfield) will only operate a 20MHz wide channel and likely using a long guard interval. More realistic data rates are 65/130/195 respectively for 1/2/3 spatial streams. – YLearn Dec 16 '19 at 21:27

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