diversity technique

Proceedings of National Conference on Recent Advances in Electronics and Communication Engineering
(RACE-2014), 28-29 March 2014

A Review of Diversity Techniques in Wireless
Communication system
Satyanand Choudhary1, Surbhi Jha2 , Prabhakar Sharma3
1,2

3

B.Tech Student, I.T.S Engineering College, Greater Noida
Assistant Professor, I.T.S Engineering College, Greater Noida
1
[e-mail]
2
[e-mail]
3
[e-mail]

Abstract—It is the technique used to compensate for fading channel impairments. It is implemented by using two or more receiving antennas. While Equalization is used to counter the effects of ISI, Diversity is usually employed to reduce the depth and duration of the fades experienced by a receiver in a flat fading channel. These techniques can be employed at both base station and mobile receivers. Spatial Diversity is the most widely used diversity technique. In this technique multiple antennas are strategically spaced and connected to common receiving system. While one antenna sees a signal null, one of the other antennas may see a signal peak, and the receiver is able to select the antenna with the best signal at any time. The CDMA systems use Rake receivers which provide improvement through time diversity.
Keywords: Equalizers, diversity, ISI ( Inter-Symbol Interference), Fading.

I.

INTRODUCTION

Diversity [2] is a technique, which is used to diminish the channel fading & is often implemented by using two or more receiving antennas. In 3G transmit diversity is used where base-stations may transmit replicas of the signal on spatially alienated antennas or frequencies. With an equalizer, diversity improves the quality of a wireless communication link without alerting the common air interface & devoid of increasing the transmitted power or bandwidth. The difference in equalization & diversity is that equalizer technique [4] is used to reduce ISI, whereas diversity technique is

References: [1] J. G. Proakis, Digital Communications. New York: McGraw-Hill, 1995. [2] A. J. Goldsmith and P. P. Varaiya, “Capacity of fading channels with channel side information,” IEEE Trans. Inform. Theory, vol. 43, pp. 1986–1992, Nov. 1997. [3] G. Foschini and M. Gans, “On limits of wireless communications in a fading environment when using multiple antennas,” Wireless Pers. Commun., pp. 311–335, 1998. [4] Prabhakar Sharma & Shilpa Sharma,book of nandani publication, 1st Edition, ISBN 978-93-81126-42-4. [5] T.S. Rappaport, Wireless Communication-Principle and Practice, Prentice Hall, 2nd Edition, 2002, [6] Webb, William. “Introduction to Wireless Local Loop”. Boston: Artech House, 1998. 6