The impact of transceiver distortions on the spectral properties of random CDMA with constant envelope

This paper studies the robustness of spreading sequences designed for random code-division multiple-access (CDMA) schemes with continuous-time constant envelope (CE) against transmitter impairments. It is shown that by taking into account the impairments of a real implementation the investigated design algorithm finds a set of spreading waveforms with exactly constant envelope which would even satisfy the transmit signal spectrum requirements of the 3rd generation Universal Mobile Telecommunications System (UMTS) standard. This shows that CE CDMA is compatible with linear CDMA while achieving higher power efficiency and supporting the usage of standard linear multiuser detection algorithms.