Forum

1. can the type of antenna in use affect the WLAN throughput?

According to my understanding, yes it does. lets consider a case in which we use a directive antenna and an omni antenna. the directive antenna puts its output power in a particular direction up to a far distance in comparison to omni antenna in the same direction.hence with the increase in the distance from the antenna the throughput decreases.so the antenna type does matter for the througput.or is it like that , for a constant distance from the antenna, both will provide same throughput??


2.Can the use of VLANs on switch be considered as the WLAN security solution?
(VLANs are not covered in the study guide, should we go through them)



and plz plz do answer my previous posted messaages

1. Can the type of antenna in use affect the WLAN throughput?

It can affect the data rate at which you connect at a given distance, but it will not affect the throughput at each data rate. An directional antenna will not make a 36Mbps connection any faster than a 36Mbps connection with a different (i.e. omni) antenna.


2. Can the use of VLANs on switch be considered as the WLAN security solution?

This one is a bit subjective, but VLAN's don't make the WLAN any more secure, but it does help secure the LAN that the WLAN is connected to.

Question 1

Antenna type alone will not make a great change in throughput. You must look at several factors. The gain of the antenna, the coverage pattern, and the physical location of the STAs in the coverage area are all important factors in addition to the physical environment and number of associated STAs. STA's closer to the antenna of the AP normally have higher data rates and better modulation schemes available. If you change the coverage and or gain of the antenna you change the sizes of the "data rings" arround the AP and thus the throughput may change. This increase in coverage may result in allowing a distant STA that could not connect before to now connect, but at a lower data rate and possibly a less efficent modulation method, lowering throughput. You should also look at the allowed data rates of the AP and limit the allowed number of associations. Perhaps lowering the power settings and colocating more APs would be a better effort in increasing throughput.

Question 2

I think Gene answered this when he stated "This one is a bit subjective, but VLAN's don't make the WLAN any more secure, but it does help secure the LAN that the WLAN is connected to."

Remember wireless networks work in layers 1 and 2, requirements for security are not the same as on a bounded network.

if two antennas provide same data rate at a fixed distance, will their throughput be different ????how come???

if two antennas( omni v/s directional) provide same data rate at a fixed distance, will their throughput be different ????how come???

If all esle in the environment remains the same, throughput should not change. The coverage area would, but given the same data rate and no other variation, throughput should remain the same.

thanx alot for ur kind replys....they were really useful....