Errata – Practical Digital Wireless Signals

All readers of this book are strongly encouraged to notify me directly if you notice an error in this book. To date, here are the errors which have been found and their corrections:

1) Equation (D.5b) reads 1) Equation (D.5b) should read as
2) Figure 2.38 has the wrong x-axis labels, though the curve is correct. The correct and complete replacement for Figure 2.38c is here:
3) The discussion on signal order for OFDM on page 208 is not consistent with conventional use. And Figure 7.22 needs to be replaced. Signal Order of OFDM
Even though the individual OFDM subcarriers may be QAM modulated with simple low-order constellations, the number of information bits that the entire OFDM symbol carries will get very large when many subcarriers are used. The order of the entire OFDM signal is equal to the count of the total signal states available to the OFDM signal. This is an identical definition of signal order to that used in all other previous signals. Assuming that all OFDM subcarriers are carrying data we write the order as
Examples of how high the OFDM signal order might get, using (7.29), are presented in Figure 7.22. With the number of bits per OFDM symbol often exceeding several hundred the OFDM signal order can easily exceed 100 billion. Clearly OFDM is a very complicated signal indeed.With these very high signal orders, it is intuitive to think that an OFDM signal will not be very tolerant of transmission distortion. After all, an OFDM signal using 4-QAM on only 5 subcarriers has the same signal order as 1024-QAM (Figure 7.1d). This reduced tolerance of signal distortion is seen in the accepted standards: a typical OFDM distortion limit (measured by EVM) is 3%, while the transmitter signal distortion allowed on QAM signals is often allowed to exceed 15%. View corrected Figure 7.22
4) Page 73, journal title is missing in next to last entry of ‘For further reading’ L. Gao,, “Optimum Filtering For Maximum Channel Capacity In PSK And FSK Modulation Systems,” Proceedings of the 40th Midwest Symposium on Circuits and Systems (1997), vol. 2, Aug. 1997, pp. 1386 – 1389