Joint adaptive beamforming and perfect power control in wireless networks over power control error

Mohamad Dosaranian-Moghadam

doi:10.17485/ijst/2012/v5i10.10

Abstract

In this paper, we use joint perfect power control (PPC) and adaptive beamforming algorithms as constrained least mean square (CLMS) and conjugate gradient adaptive beamforming (CGBF) in a 2D urban environment. The CLMS algorithm is capable of efficiently adapting according to the environment and able to permanently maintain the chosen frequency response in the look direction while minimizing the output power of the array. In addition, with the CGBF algorithm, the desired users’ signal in an arbitrary path is passed and the inter-path interference (IPI) is canceled in other paths in each RAKE finger. The adaptability of the algorithms is closely observed for uniformly spaced linear array. In addition, in this paper, we present switched-beam (SB) technique. In the SB technique by using a number of fixed, independent, or directional antennas we increase the uplink capacity of the wireless systems. Also, we study an analytical approach for the evaluation of the impact of power control error (PCE) on wireless communication systems. Simulation results indicate that the SB technique is able to considerably increase the signal to interference plus noise ratio (SINR) of desired user in comparison with other algorithms. In addition, we observe that the SINR in the CLMS algorithm is lower than the CGBF algorithm. Finally, we discuss two parameters of the PCE and path-loss exponent and their effects on capacity of the system via some computer. Keywords: Adaptive beamforming, Power control, Wireless networks

Highlights

It is generally acknowledged that a viable approach for increasing the capacity of wireless cellular systems in the reverse link is represented by antenna arrays (Chang et al, 2002; Abrardo, 2003; Wang, 2009; Kumatani et al, 2009; Zhang et al, 2009; Yang & Fang, 2009)
We studied joint adaptive beamforming algorithm and perfect power control in a 2D urban environment in reverse link
It has been observed that the signal to interference plus noise ratio (SINR) of desired user with the conjugate gradient adaptive beamforming (CGBF) algorithm is higher than that with the constrained least mean square (CLMS) algorithm, because in the CGBF algorithm, the inter-path interference (IPI) is removed whereas in CLMS algorithm it is not canceled

Summary

Introduction

It is generally acknowledged that a viable approach for increasing the capacity of wireless cellular systems in the reverse link (uplink) is represented by antenna arrays (Chang et al, 2002; Abrardo, 2003; Wang, 2009; Kumatani et al, 2009; Zhang et al, 2009; Yang & Fang, 2009). In order to minimize the variance or average power at the output of the beamformer subject to maintaining unity gain at the direction of the desired user signal. It should be mentioned that for the array antenna weight vector elements in the CLMS algorithm and for big μ , will converge after a few iteration (is approximately equal to the number of beamformer weights, i.e., m = N ) (Dosaranian-Moghadam et al, 2010; Dosaranian-Moghadam et al, 2010; Dosaranian-Moghadam et al, 2010; Dosaranian-Moghadam et al, 2011).

Results

Conclusion