I have been using some RB751Us for a while now and have some observations about some surprisingly poor wireless performance and I'd like other's views on the topic.
My test environment:
btest server running on a desktop with an Intel i3 CPU running at 3 GHz with Windows 7 x64 always wired with a 100 Mbit connection.
btest client running on a laptop with an Intel i5-2520m CPU running at 2.5GHz with Windows 7 x64
Client wireless adapter (for some of the tests (see below)) is an Intel 6205.
Baselines:
Using an 100 Mbit Ethernet connection to the laptop:
btest results: 46 Mbps both directions, 79 Mbps rcv, 80 Mbps send
If I use the laptop's Intel wireless: card to connect to a Cisco Aironet Series 1200 AP (G only)
my btest results are: 13Mbps both directions, 22 Mbps rcv, 23 Mpbs send (wireless speeds show 56 Mbit)
If I connect RB751U to the ethernet port of the laptop, configure the RB751U as a bridged-client and test again to the Cisco AP
my btest results are: 6 Mbps both directions, 12 Mbps rcv, 11 Mbps send. (wireless speeds show 18/24 Mbit)
Note that this is about 1/2 of the performance of the Intel card. Why?
Further testing:
I use the laptop's Intel wireless card to connect to a RB751U running as an AP with two chains using the N protocol with a 20 MHz channel width.
my btest results are: 17 Mbps both directions, 18 Mbps rcv, 33 Mbps send (wireless speeds show 120Mbit/39 Mbit (Tx/Rx))
This seems disappointing so I decide to run the following test:
Laptop Intel wireless card connected to a RB751U running as an AP with two change using the N protocol with a 40 MHz channel width. The wireless speeds negotiate to 240Mbit Tx/39 Mbit Rx.
btest results are: 19 Mbit both directions, 18 Mbit rcs, 39 Mbit send
This is also disappointing and not really much better than the 20 Mhz channel width.
So I try to run two final tests with a RB751U as an AP and another RB751U as the client (connected to my laptop with ethernet).
With a 20 MHz channel width
btest shows 7 Mbps both directions, 12 Mbps rcv, 17 Mbps send
With a 40 MHz channel width
btst shows 11 Mpbs both directions, 17 Mbps rcv, 21 Mbps send
Why are all these results so disappointing? Does anyone have better results to report using the RB751U?