Nonlinear effects in lte downlink signals and application of a compensation technique at the receiver side

Abstract

bandwidth. Therefore, depending upon a wider AR bandwidth or a higher gain requirement, the h air can be chosen accordingly. Effects of Array Size of Element of SPSNext, we study the effect of array size of element of SPS. Three different stacked array sizes of unit-cell, namely, 2 Â 2, 4 Â 4 and 6 Â 6, are investigated with a fixed height of air gap of 7.5 mm. Figure 7(a) shows the return losses as a function of array sizes. In this variation, we found that resonant frequency is moved to higher frequencies with array size decreases. It is noted that 4 Â 4 array size has the widest bandwidth of 10-dB return-loss. Figure 7(b) shows the comparison of AR and realized gain with array sizes. It is observed that the array size has significant effect on the AR and realized gain. The realized gain is not completely correlated with AR. It is concluded from Figure 7(b) that the widest 3-dB AR bandwidth can be achieved by choosing an array size of 4 Â 4. The realized gain increases with the increase of the array size. The enhancement of the AR can be achieved by selecting the array size of SPS.This parametric study has helped to identify dimensional trends of the most important parameters and facilitated the design of a single-feed CP antenna. CONCLUSIONSThis article demonstrated that the gain, impedance and AR bandwidths of a CP microstrip antenna can be significantly enhanced by stacking with a periodic structure. With the use of a periodic structure superstrate, a wideband and high gain CP-MPA was designed. A key feature of this design is loaded the periodic structure superstrate above the CP patch source. The SPS cannot only be used for increasing the impedance bandwidth, but also the gain and ARBW. The fabricated prototype attained an overlapped bandwidth (return loss ! 10 dB and AR 3 dB) of 10.1% (2.328-2.576 MHz). Average gain of 8 dBi has been achieved across the overlapped bandwidth. The cross-polarization discrimination of 20 dB is observed within the overlapped bandwidth. From measured results, the front-to-back ratio is more than 30 dB. ACKNOWLEDGMENTSThe authors would like to acknowledge the Microwave and Wireless Communication Laboratory at the Chinese University of Hong Kong, for the assistance in the antenna measurement. This work is partially supported by the Faculty of Engineering, King Mongkut's University of Technology North Bangkok. ABSTRACT: This article proposes a nonlinear compensation technique for long-term evolution downlink signals based on the memoryless solidstate power amplifier model, which provides a simple and effective linearization technique at the receiver side, allowing a reduction in the error vector magnitude measured characteristics. The error vector magnitude per subcarrier is analyzed for different appropriate resource blocks allocations in the long-term evolution signal to examine the distortion due to the nonlinear effects produced by a power amplifier in the experimental setup.