identity of various spectral masks
I know that QPSK and X-QAM have different MASK.
Spectrum Mask is a requirement, and not a behavior of a modulation signal.
Not well designed systems can make the digital signal looks badly, and sometimes in this situation you cannot differentiate between modulation spectrum types.
I am not new to this terminology but new to their design. Actually I am trying to implement one of the early modems for WiFi which uses 802.11ac and for that I require 256 QAM with 20 or 40 or 80 or even 160 MHz bandwidth. Can anyone provide me with the material to read or book title so that I can gain bit of knowledge. Thank you in advance
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I am not new to this terminology but new to their design. Actually I am trying to implement one of the early modems for WiFi which uses 802.11ac and for that I require 256 QAM with 20 or 40 or 80 or even 160 MHz bandwidth. Can anyone provide me with the material to read or book title so that I can gain bit of knowledge. Thank you in advance
FSK, GFSK, MFSK (=frequcny shift keying, information is in freqeuncy.. 1bit=1symbol) where as QPSK (=quardature phase shift keying, information is in phase, 2bits=1symbol). Now if you want more througput you need higher modulation scheme i.e. 16QAM, 64QAM. No matter what modulation scheme you use (TX chain) you will always have to make sure that your spectrum at either transceiver or PA output or @ANT comply with the mask defined by the standard-could be GSM, WCDMA, LTE etc. The goal is to make sure that it do not violate other channel or frequency used by other user.
One other thing is non-linearity behavior of the TX chain (especially PA is the main contributor of the chain) as it will produce some harmonics thus we will see spectral re-growth perhaps interferring other user. When we talk about TX there are few things to look into....phase error, frequency error, spectrum emission mask so on and so on.