On the Peak-to-Average Power Ratio Reduction Problem for Orthogonal   Transmission Schemes
  High peak values of transmission signals in wireless communication systems lead to wasteful energy consumption and out-of-band radiation. However, reducing peak values generally comes at the cost some other resource. We provide a theoretical contribution towards understanding the relationship between peak value reduction and the resulting cost in information rates. In particular, we address the relationship between peak values and the proportion of transmission signals allocated for information transmission when using a strategy known as tone reservation. We show that when using tone reservation in both OFDM and DS-CDMA systems, if a Peak-to-Average Power Ratio criterion is always satisfied, then the proportion of transmission signals that may be allocated for information transmission must tend to zero. We investigate properties of these two systems for sets of both finite and infinite cardinalities. We present properties that OFDM and DS-CDMA share in common as well as ways in which they fundamentally differ. 
Holger Boche and Brendan Farrell
cs.IT math.IT