20MHz vs 40MHz. The N spec is able to use 40MHz of bandwidth for increased data rates, but to maintain compatibility with legacy systems, it requires one main 20MHz channel plus a free adjacent channel at ±20MHz. The main channel is used for legacy (a/b/g) or other clients that aren't able to transmit at 40MHz.
Feb 16, 2000 · Using the above formula with an MSS of 1460 bytes, we can plot the throughput as a function of loss and RTT as shown in the chart below for the range RTT from 0.25ms (typical LAN RTTs) to 650ms (typical geostationary satellite speed).
Oct 25, 2019 · Chart of ADSL2/2+ and ADSL connection speed against distance from the exchange ADSL2+ provides most benefit for premises close to the exchange. For distances between 3 km and 3.5 km, where ADSL speeds have fallen well below 10Mbps, ADSL2+ and ADSL2 still provide worthwhile increases in connection speeds.