Constructing multirate CDMA signals with controlled peak-to-average power ratio using balanced incomplete block designs

A multirate modulation scheme with controlled peak-to-average power (PAV) ratio and suitable for code division multiple access techniques is introduced. The scheme utilizes codes drawn from a fixed set of Walsh-Hadamard codes but other code families can also be used. The strategy employs balanced incomplete block designs to define the multirate data symbols, with the objective being to reduce depletion of the code pool while controlling the PAV ratio. Existing multirate schemes are reviewed. Code depletion and PAV ratio characteristics of the proposed scheme are compared to existing schemes. Symbol error performance of the proposed scheme in an additive white Gaussian noise channel is examined. It is concluded that the proposed scheme, unlike the two other existing schemes that are examined, strikes a good balance between PAV ratio, code depletion, and error performance.