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Relay Assisted MIMO Transmission System

Abstract
Relay assisted Multiple Input Multiple Output transmission system (MIMO) are expected to be a part of future infrastructure based wireless networks. Besides coverage extensions, such relays can posses high transmission rates, higher speed and larger capacity than its predecessors. MIMO opens a new dimension for wireless broadband communication, mobile wireless access. In this paper we present the concept of a relay-assisted MIMO transmission system for wireless communication, via conceptual study of relay-assisted MIMO transmission system.


Introduction

It is believed that next generation wireless network will adopt MIMO technology to have higher speed and larger capacity than its predecessors . MIMO opens a new dimension for an effective communication. They can offer multiplexing gains and diversity gain (robustness of communication under undesirable channel effects) and are receiving much attention nowadays thanks to their properties for increasing the performance of wireless communication.
It is expected that future wireless broadband communication systems will operate beyond 5GHz, which relays on the use of multiple antennas at transmitter/receiver side. It is a very promising technique to mitigate the channel fading and thus improving the cellular system capacity. However, it is capable of accomplishing what is undertaken it has to face some problems, hence relay assisted MIMO was proposed.
Relay transmission has been identified as one of the core technologies that could enable robust high speed information transfer over challenging wireless environment . By positioning the relays in between source and destination, it is possible to benefit the transmission in terms of higher transmission rate and wider coverage, due to such benefits, much research has been devoted in analyzing the relay channel and realizing its potential. MIMO system enhances the system’s performance by increasing the number of relays between them. By replacing the multiple transmitters with relay nodes, the system is able to achieve the more homogeneous power distribution by reducing deployment and operational expenditures. Thus the goal of relay assisted MIMO system is to increase the rank of compound channel matrix, high throughput and page link range without additional bandwidth. It achieves this by higher spectral efficiency and page link reliability. In this paper we present, a conceptual study of relay-assisted MIMO system in detail.
MIMO

MIMO is an antenna array technology for wireless communication in which multiple antennas are used at both source and destinations . Antenna array technology is the use of multiple antennas at the transmitter or the receiver. Antennas at each end of the communications circuit are combined to minimize errors and optimize data speed. MIMO is one of several forms of smart antenna technology. By configuring multiple antennas at both the transmitting and receiving side, the channel capacity may be improved proportionally to the minimum number of antennas at the transmitter and the receiver.
In conventional wireless communications, a single antenna is used at the source, and another single antenna is used at the destination. In some cases, this gives rise to problems with multipath effects. When an electromagnetic field is met with obstructions such as hills, canyons, buildings, and utility wires, the wave fronts are scattered, and thus they take many paths to reach the destination. The late arrival of scattered portions of the signal causes problems such as fading, cut-out and intermittent reception. In digital communications systems such as wireless Internet, it can cause a reduction in data speed and an increase in number of errors. The use of two or more antennas, along with the transmission of multiple signals (one for each antenna) at the source and the destination, eliminates the trouble caused by multipath wave propagation, and can even take advantage of this effect. MIMO technology has attracted in wireless communication, since it offers significant increase in data throughput and page link range without additional bandwidth or transmit power. It achieves it by higher spectral efficiency and page link reliability or diversity. Because of these characteristic, MIMO is a current theme of international wireless research.