wat r smart antennas?

Answer 1

Smart Antenna refers to a system of antenna arrays with smart signal processing algorithms that are used to identify the direction of arrival (DOA) of the signal, and use it to calculate beamforming vectors, to track and locate the antenna beam on the mobile/target. The antenna could optionally be any sensor.

Smart antenna techniques are used notably in acoustic signal processing, track and scan RADAR, Radio astronomy and Radio telescopes Radio Telescopes, and mostly in cellular systems like W-CDMA and UMTS.

Smart antennas have two main functions:
1. DOA estimation.
2. Beamforming.

DOA estimation:
The smart antenna system estimates the direction of arrival of the signal, using any of the techniques like MUSIC (Multiple Signal Classification) or ESPRIT (Estimation of Signal Parameters via Rotational Invariant Techniques) algorithms, or their derivatives. They involve finding a spatial spectrum of the antenna/sensor array, and calculating the DOA from the peaks of this spectrum. MUSIC involves calculation of eigenvalues and eigenvectors of an autocorrelation matrix of the input vectors from the receiving antenna array. These calculations are computationally intensive.


Beamforming:
Beamforming is the method used to create the radiation pattern of the antenna array by adding constructively the phases of the signals in the direction of the targets/mobiles desired, and nulling the pattern of the targets/mobiles that are undesired/interfering targets. We basically implement a simple FIR tapped delay line filter to do this. The weights of this FIR filter may also be changed adaptively, and used to provide optimal beamforming, in the sense that it reduces the MMSE between the desired and actual beampattern formed. Typical algorithms are the steepest descent, and LMS algorithms. Beamforming is a latest technology being used for various purposes.

Good Luck.

Answer 2

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Answer 3

Smart Antennas

Need for Smart Antennas

Wireless networks face ever-changing demands on their spectrum and infrastructure resources. Increased minutes of use, capacity-intensive data applications and the steady growth of worldwide wireless subscribers mean carriers will have to find effective ways to accommodate increased wireless traffic in their networks. However, deploying new cell sites is not the most economical or efficient means of increasing capacity.

Wireless carriers have begun to explore new ways to maximize the spectral efficiency of their networks and improve their return on investment. Smart antennas have emerged as one of the leading innovations for achieving highly efficient networks that maximize capacity and improve quality and coverage.

What are Smart Antennas?

Smart antennas provide greater capacity and performance benefits than standard antennas because they can be used to customize and fine-tune antenna coverage patterns that match the traffic conditions in a wireless network or that are better suited for complex radio frequency (RF) environments. Furthermore, smart antennas provide maximum flexibility by enabling wireless network operators to change antenna patterns to adjust to the changing traffic or RF conditions in the network.

The History of Smart Antenna Development

Early smart antennas were designed for governmental use in military applications, which used directed beams to hide transmissions from an enemy. Implementation required very large antenna structures and time-intensive processing and calculation.

As personal wireless communications began to emerge, it was evident that interference in wireless networks was limiting the total number of simultaneous users the network could handle before unacceptable call quality and blocking occurred. Since the narrow beams of the early governmental smart antennas created less overall interference, researchers began to explore the possibility of extending the use of smart antennas to reduce overall network interference in commercial wireless networks, thus increasing the total number of users a wireless system could handle in a given block of spectrum. But the hardware and processing technologies required to perform the complex calculations in the very small spaces of time available in personal wireless communications would prove to be a hurdle that was extremely difficult to overcome. A few select companies have successfully developed and introduced smart antenna technologies into commercial wireless networks.

Smart Antennas Today

Today, smart antennas have been widely deployed in many of the top wireless networks worldwide to address wireless network capacity and performance challenges.

Several different versions of smart antennas are either in development or available on the market today. Appliqué smart antenna systems can be added to existing cell sites, enabling software-controlled pattern changes or software-optimized antenna patterns that have produced capacity increases of up to 35-94% in some deployments. Appliqué smart antenna systems provide greater flexibility in controlling and customizing sector antenna pattern beamwidth and azimuthal orientation over that of standard sector antennas.

A second approach, embedded smart antennas, uses adaptive array processing within the channel elements of a base station. The smart antenna processing takes place in the base station signal path, using a custom, narrow beam to track each mobile in the network. Embedded smart antenna system trials have been proven to deliver 2.5-3 times the capacity of current 2-2.5G base stations.

Applications of Smart Antenna Technologies

As demonstrated by deployments in many of the top wireless markets, smart antennas are a practical, economical solution to many of the toughest challenges faced by wireless operators. As market conditions have changed, through new product offerings smart antennas have expanded outside of their traditional realm into totally new applications, such as antenna sharing and optimization efficiency.

Wireless operators could employ different smart antenna technologies at different stages in their network evolution, depending upon the challenges they face. Innovative smart antenna solutions have been proven play an integral part of an operator's migration strategy to 3G technologies.


Smart Antenna Resources
Access presentations, white papers and Digevents on Smart Antennas

Answer 4

You can usually recognize them by the pocket protectors and the glasses.

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