| Electronics > Beginners |
| Wifi Bandwidth - what am I missing? |
| (1/2) > >> |
| paulca:
So a normal Wifi channel is 20Mhz wide. A higher rate channel is 40Mhz wide. However the data rates supported on those channels (on 2.4Ghz) are 54Mbps and 108Mbps. I missing something, but if memory serves me right, "bandwidth" is originally, literally that, the width of the band. Now if I have a 20Mhz bandwidth, then surely my maximum data rate is 20Mhz/2 = 10Mbps. What am I missing? |
| IanB:
1 MHz ≠ 1 Mbps |
| Paul Rose:
Nyquist formula in a noise free channel: Rate = 2 * Bandwidth * log2( Number of Signal Levels ) There are lots of resources out there. Here is one at random: https://witestlab.poly.edu/blog/nyquist-formula-relating-data-rate-and-bandwidth/ |
| TK:
It is the modulation scheme (64 QAM for 802.11g) what gives you 54Mbps with WiFi. 802.11n / 802.11ac can do 256QAM modulation. Cable Modem uses similar modulation schemes to achieve 1Gbps. |
| IDEngineer:
--- Quote from: TK on September 24, 2018, 07:58:00 pm ---It is the modulation scheme (64 QAM for 802.11g) what gives you 54Mbps with WiFi. 802.11n / 802.11ac can do 256QAM modulation. Cable Modem uses similar modulation schemes to achieve 1Gbps. --- End quote --- Exactly this. Modulation decouples you from a strict "bandwidth to bitrate" relationship. Spend a little time Googling modulation schemes - then think about how you'd craft a receiver to decode some of the dense constellation ones in real time. :o |
| Navigation |
| Message Index |
| Next page |