This paper proposes the new radix-24 FFT algorithm and an efficient pipeline FFT architecture based on the algorithm for wideband OFDM systems. The proposed pipeline architecture has the same number of multipliers as that of the radix-22 algorithm. However, the multiplication complexity is reduced more than 30% by using the newly proposed CSD constant multipliers instead of the programmable multipliers. From the synthesis simulations of a standard 0.35 µm CMOS SAMSUNG process, the proposed CSD constant complex multiplier achieved a reduction of more than 60% of the power consumption/area when compared with the conventional programmable complex multiplier.

This paper proposes a new modified radix-24 FFT algorithm and an efficient pipeline FFT architecture based on this algorithm for OFDM systems. This pipeline FFT architecture has the same number of multipliers as that of the radix-22 algorithm. However, the multiplication complexity could be reduced by more than 30% by replacing one half of the programmable multipliers by the newly proposed CSD constant multipliers. From the synthesis simulations of a standard 0.35 µm CMOS SAMSUNG process, a proposed CSD constant complex multiplier achieved more than 60% area efficiency when compared to the conventional programmable complex multiplier. This promoted efficiency could be used to the design of a long length FFT processor in wireless OFDM applications, which needs more power and area efficiency.

In the design of Space Time Block Coding (STBC), for an arbitrary complex signal constellation with a size above 2 as well as a real signal matrix with a size above 8, it is difficult to acquire full code rate and full transmit diversity simultaneously. In this letter, an efficient selective receiver switching scheme is proposed for STBC with the full code rate and non-orthogonal design with the example of a 4-by-4 matrix. In the proposed scheme with the aid of beamforming, we divide the received signals into two groups according to the encoded matrix. By this way, we can eliminate the interference from the neighboring signals by more than half.

Blind beamforming plays an important role in multiple-input multiple-output (MIMO) Systems, radar, cognitive radio, and system identification. In this paper, we propose a new algorithm for multiple blind beamforming algorithm based on the least square constant modulus algorithm (LSCMA). The new method consists of the following three parts: (a) beamforming of one signal with LSCMA. (b) direction-of-arrival (DOA) estimation of the remaining signals by rooting the weight vector polynomial. (c) beamforming of the remaining signals with linear constraints minimum variance (LCMV) method. After the convergence of LSCMA, one signal is captured and the arrival angles of the remaining signals can be obtained by rooting the weight vector polynomial. Therefore, beamforming can be quickly established for the remaining signals using LCMV method. Simultaneously the DOA of the signals can also be obtained. Simulation results show the performance of the presented method.