Changes between Version 21 and Version 22 of WARPLab/Examples/OFDM

Timestamp:

Nov 2, 2015, 4:17:56 PM (9 years ago)

Author:

chunter

Comment:

--

WARPLab/Examples/OFDM

@@ -90 +90 @@
 
  * [https://en.wikipedia.org/wiki/Carrier_frequency_offset Carrier Frequency Offset (CFO)] - The center frequency of the transmitter will not perfectly match the center frequency of the receiver. Unless corrected, this will de-orthogonalize the OFDM subcarriers and cause inter-carrier interference (ICI). CFO is typically corrected in the time domain via multiplication with a digital carrier whose frequency negates the CFO estimate.
- * Phase Error - Even after CFO is corrected in the time domain, there is typically a residual phase error component that must be corrected in the frequency domain.
+ * Phase Error - Even after CFO is corrected in the time domain, there is typically a residual phase error component that must be corrected in the frequency domain and tracked over time. OFDM systems employ multiple pilot subcarriers to enable this recovery system.
  * Sampling Frequency Offset (SFO) - The temporal duration of a sample is slightly different at the receiver and transmitter due to different sampling clocks. Over the course of a reception, the relative sample periods will drift apart from one another. This manifests as larger phase error for the outer subcarriers.