POWER ENVELOPE VARIATION IMPROVEMENT OF DOWNLINK LTE SYSTEM USING COMPLEX NUMBER MANIPULATION APPROACH

Abstract

Today the world is witnessing very significant developments in the world of digital communications. For that, the subscribers are demanding for quality and speed for the available services. To achieve these objectives, must be accurate and low impurity communication devices available. The orthogonal frequency division multiplexing (OFDM) scheme, is the downlink modulation scheme utilized in the long term evolution (LTE) system. Because of the coherent addition of the subcarriers, the output power variation will show high peaks compared with the average, known as Crest factor, thus, the amplification gain is degraded and intermodulation distortion will appears. Different sorts of schemes have been introduced to mitigate these problems, but either on the expense of complexity or the bit error rate (BER) performance degradation. In this paper, a novel simple to implement algorithm suggested by the authors to mitigate the high Crest factor. The suggested approach is based on complex numbers manipulation, by exchanging the real and imaginary parts, to destroy the coherence order of the OFDM subcarriers, leading to lower crest factor. Results show that the computational complexity and the reduction gain are improved significantly.