Changes between Version 22 and Version 23 of WARPLab/Examples/OFDM

Timestamp:

Nov 3, 2015, 10:15:01 AM (9 years ago)

Author:

chunter

Comment:

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WARPLab/Examples/OFDM

@@ -89 +89 @@
 Typically, a transmitter and receiver are each clocked independently. This independence manifests in three different degradations that must be dealt with by a wireless receiver:
 
- * [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.
+ * [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. This example uses [#cite1 [1]]
  * 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.
@@ -125 +125 @@
 == Limitations ==
 This example is intended as a starting point for researchers wishing to use WARPLab to prototype a wireless communications link. This examples does not implement some some blocks common in deployed OFDM systems, such as scrambling, interleaving and error correcting coding. For an example of a real-time OFDM implementation that implements all of these subsystems, please see the PHY in the [wiki:802.11 802.11 Reference Design].
+
+== References ==
+
+=== {{{[1]}}} [https://scholar.google.com/scholar?q=%22Robust+Frequency+And+Timing+Synchronization+For+OFDM%22&btnG=&hl=en&as_sdt=0%2C44 Schmidl, Timothy M., and Donald C. Cox. "Robust frequency and timing synchronization for OFDM." Communications, IEEE Transactions on 45.12 (1997): 1613-1621.]  === #cite1