Square Complex Orthogonal Designs with no Zero Entry for any $2^m$   Antennas
  Space-time block codes from square complex orthogonal designs (SCOD) have been extensively studied and most of the existing SCODs contain large number of zeros. The zeros in the designs result in high peak-to-average power ratio and also impose a severe constraint on hardware implementation of the code while turning off some of the transmitting antennas whenever a zero is transmitted. Recently, SCODs with no zero entry have been constructed for $2^a$ transmit antennas whenever $a+1$ is a power of 2. Though there exists codes for 4 and 16 transmit antennas with no zero entry, there is no general method of construction which gives codes for any number of transmit antennas. In this paper, we construct SCODs for any power of 2 number of transmit antennas having all its entries non-zero. Simulation results show that the codes constructed in this paper outperform the existing codes for the same number of antennas under peak power constraint while performing the same under average power constraint. 
Smarajit Das and B. Sundar Rajan