CMA Algorithms Research Articles

Performance Analysis of LMS, RLS, CMA Algorithms for Beamforming in Smart Antenna Systems

Smart antenna systems strengthen wireless mobile communication, with enhancement over conventional systems, by projecting the signal power in narrow beams towards the desired users and suppressing the signal power towards unwanted users or interferers. Different DOA estimation and beamforming algorithms play crucial role in smart antenna system. In beamforming algorithms, using different techniques complex weights are calculated and applied to the signals from the smart antenna array elements to enhance signals of interest and suppress signals not of interest. In this article Least Mean Square(LMS) technique, Recursive Least Square(RLS)technique and Constant Modulus (CMA)technique adaptive beamforming algorithms are implemented, analyzed and compared using MATLAB simulations to help users to choose amongst them as per the their need, ease and suitability.

COMPARITIVE ANALYSIS OF DOA AND BEAMFORMING ALGORITHMS FOR SMART ANTENNA SYSTEMS

This paper revolves around the implementation of Direction of arrival and Adaptive beam-forming algorithms for Smart Antenna Systems. This paper also investigates the implementation of algorithms on various planner array geometries viz. circular and rectangular. Music algorithm is primarily finds the possible location of desired user and adaptive beam-forming algorithms such as LMS, RLS and CMA algorithms adapts the weights of the array. DOA estimation gives the maximum peak of spectrum with respect to angle of arrival where the desired user is supposed to exist. After DOA estimation weights of array antenna are changed with the changing received signal. This methodology is called as Spectral estimation, which allows the antenna pattern to steer in desired direction estimated by DOA and simultaneously null out the interfering signals. Rate of convergence is the major criterion for comparison for adaptive beam-forming algorithms.

스텝사이즈에 따른 적응 알고리즘을 이용한 간섭제거 중계기

In the paper, we propose a new Signed LMS(Least Mean Square) algorithm for ICS(Interference Cancellation System). The proposed Signed LMS algorithm improved performances by adjusting step size values. At the convergence of 1000 iteration state, the MSE(Mean Square Error) performance of the proposed Signed LMS algorithm with step size of 0.067 is about 3 ∼ 18 dB better than the conventional LMS, CMA algorithm. And the proposed Signed LMS algorithm requires 500 ∼ 4000 less iterations than the and LMS and CMA algorithms at MSE of -25dB.

Adaptive Array Antenna Using On-Off and CMA Algorithms for Microwave RFID Readers

This paper proposes an adaptive antenna using a combination of on-off and CMA algorithms. With the proposed technique, the on-off algorithm is first employed to search for a desired signal direction in which maximum received power is achieved. Then, interference is suppressed by performing CMA. Simulations are conducted according to the potential application of the proposed adaptive antenna. The simulation results show the SINR improvement implying that the proposed adaptive antenna can be applied to microwave RFID systems in order to resolve reader collision. Furthermore, the proposed adaptive antenna is implemented and then experimented. The experimental results verify that the proposed adaptive antenna can reduce interference resulting in the collision problem.

New class of zero-forcing cost functions in blind equalization

The use of gradient descent recursive algorithms in blind adaptive equalization requires a cost function with a unique minimum such that the FIR equalizer setup removes sufficient intersymbol interference (ISI). A class of such cost functions is proposed. The newly proposed class is based on minimizing the difference between any two norms of the joint channel-equalizer impulse response, each raised to the same power, i.e., /spl par//spl middot//spl par//sub p//sup /spl zeta//-/spl par//spl middot//spl par//sup /spl zeta///sub q/, where p<q. A set of implementable recursive online algorithms using the above cost functions is also derived for QAM inputs. Some examples show that the above class could be unimodal in equalizer weights. In addition, results of analysis of the effects of additive white Gaussian noise (AWGN) on the ISI for the /spl par//spl middot//spl par//sup 4//sub 2/-/spl par//spl middot//spl par//sub 4//sup 4/ cost functions' algorithm as well as the well-known CMA algorithm are presented. It is shown that for both of the above algorithms, the AWGN affects the residual ISI only in O(1/SNR/sup 2/) under a high SNR assumption. Extensive simulations show that the performance of the newly proposed algorithms is comparable with the CMA algorithms' performance without the misconvergence.