Generally, this disclosure provides apparatus and methods for improved User Equipment mobility in wireless heterogeneous networks. According to the present invention, the silicon film within the isolation trench can be substantially regarded as a part of the silicon substrate. Thus, the frequency translator can be readily implemented in hardware. In contrast to related methods of the prior art, each nulling vector is obtained from a channel matrix of estimated channel coefficients without performing any matrix inversion operations, and only a single pseudoinverse related to the channel matrix is computed. In actual use, the solder paste of the present invention can maintain good coating and printing ability for long time, further can endure preheating under high temperatures.