802.11 questions

harryd

hello,
i have some questions and i would appreciate it if someone can help me with it

1- regarding the half duplex nature of WiFi, let say the practical throughput of a 802.11g network is 20mbps. can i use the whole bandwidth to send or receive or the bandwidth is divided into 2 independent portion ? to be more clear .... can i send at 20mbps or receive at 20mbps? or i only use 10mbps to receive and the other 10mbps is reserved for sending


2- in WiFi, the channel can only be used by a single user, this means that if you want to send something you have to wait. why don't we see this in real world? or it happens so fast we don't feel the waiting time.

3-there is a Meraki AP with a fast-ethernet Port (10/100Mbps) that offers 900mbps ( 3 radios 2x2 streams), how is that possible?

SteveO86

1. I'd consult some CWNA material for a more in-depth or check out the 802.11 for a more in depth explanation, but yea 20 Mbps in G is pretty good, you test the actual throughput by using iperf. Wi-Fi a shared medium meaning only a single client can communicate at a single time, look into RTS/CTS or CDMA/CA stuff.

2. Happens too fast. Looks RTS/CTS, CDMA/CA, the CWAP book will go into more detail concerning timing and IFS.

3. I'd check with the vendor documentation for how this works but most likely this will utilization 40 MHz channel bonding in the 5GHz range. Although 900 is fairly high.. I've heard of 600 but not 900. I know Cisco had a few Requirements such as WPA2/AES WMM support and so forth so vendor documentation is key.


Hope this helps.