The article misses out on explaining WHY we cannot get the promised bitrates. The answer is Shannon's limit on channel capacity, which mandates that you pay in either bandwidth or high power or low noise (SNR) to get higher capacity. Now these WiFi devices have internal rate adaptation algorithms that choose a particular modulation and coding scheme (MCS) index based on the measured SNR. A higher MCS index means better higher bits per symbol (modulation) and lower overhead code rates, and more antennas (spatial streams), which is how you get the xx Gbps bandwidth advertised on the box. List of MCS indices: http://mcsindex.com/
In today's devices, interference is considered as noise, which means that SNR simply drops to a point where the higher MCS indices are not chosen at all. So, even though the device is capable of the advertised XX Gbps bitrate, the SNR isn't high enough to switch to those higher rates.
In today's devices, interference is considered as noise, which means that SNR simply drops to a point where the higher MCS indices are not chosen at all. So, even though the device is capable of the advertised XX Gbps bitrate, the SNR isn't high enough to switch to those higher rates.