The splitters.

[Rafael Jimenez]

I found this in the IUWNE course:

"... splitters can be used to increase the number of areas a bridge or access point may cover, such as combining multiple sector antennas to cover a broader area. Know that splitters also induce at least 4 dB of loss, so range of all connected antennas will be reduced. Splitters also reduce throughput by 50%; this is because all traffic received at the access point or bridge must be received, buffered, and then retransmitted."

Can somebody give a good explanation of the part "Know that splitters also induce at least 4 dB of loss" and the part "Splitters also reduce throughput by 50%; this is because all traffic received at the access point or bridge must be received, buffered, and then retransmitted."

Thanks.

[Nicolas Darchis · Accepted solution]

First thing : never try stuff like that. It's just bringing too many problems.

1) Why the 4db loss ? Imagine a river. Now imagine you split that river in 2, you have 2 rivers right ? But each river then has half the "power", the "water flow" of the original one. Logical.

Same thing with RF power. If you split towards 2 antennas, each antenna only receive half of the power. And 4db loss is actually just a bit bigger than "half the power". A 3db loss is half the power. 4db is more like dividing by 2.5 or sth ?

2)Throughput : No matter the amount of antennas, you only have one radio receiver/transmitter on your AP. Meaning, that you cannot receive a frame from antenna A (first side of splitter) and antenna B ( second side of splitter) at the same time. You cannot either transmit on both sides at the same time. So you still share your 54Mb/s (in case of 802.11g) between your 2 antennas.

What they don't mention is that you greatly increase the amount of collisions that will occur too.

And if you have 802.11n then COMPLETELY forget about this as it ruins the 802.11n concept.

I hope it clarifies :-)