tag:blogger.com,1999:blog-40361603461739611482024-03-05T06:54:26.996-05:00BEAM FORMINGCapacity Enhancement In a Wireless Network Using BEAMFORMINGBEAM FORMINGhttp://www.blogger.com/profile/13948777650197565085noreply@blogger.comBlogger40125truetag:blogger.com,1999:blog-4036160346173961148.post-18891292997175034752011-12-04T10:03:00.002-05:002011-12-04T10:03:43.564-05:00PROJECT COMPLETION!!!!<div dir="ltr" style="text-align: left;" trbidi="on">Finally Project completed successfullyy!!<br />
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Congratss Team!!! :)</div>BEAM FORMINGhttp://www.blogger.com/profile/13948777650197565085noreply@blogger.com1tag:blogger.com,1999:blog-4036160346173961148.post-82996511569775303402011-11-07T09:39:00.002-05:002011-11-07T09:39:40.796-05:00Transmit beamforming using M-QAM<div dir="ltr" style="text-align: left;" trbidi="on"><br />
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</div><div>Follow the link for MATLAB file of Beamforming using M-QAM modulation in Rayleigh fading channel.</div><div>You can simply change the order of modulation to simulate it for M=4,16,64,128..</div><div><br />
</div><ul style="text-align: left;"><li><a href="http://www.mathworks.com/matlabcentral/fileexchange/33640">http://www.mathworks.com/matlabcentral/fileexchange/33640</a></li>
</ul></div>BEAM FORMINGhttp://www.blogger.com/profile/13948777650197565085noreply@blogger.com0tag:blogger.com,1999:blog-4036160346173961148.post-8694909750252293882011-10-04T20:21:00.003-04:002011-10-07T10:48:17.802-04:00LMS AND RLS ALGORITHMS FOR SMART ANTENNAS IN A W-CDMA MOBILE COMMUNICATION ENVIRONMENT<div dir="ltr" style="text-align: left;" trbidi="on"><br />
<ul style="text-align: left;"><li><a href="http://www.arpnjournals.com/jeas/research_papers/rp_2009/jeas_0809_231.pdf">http://www.arpnjournals.com/jeas/research_papers/rp_2009/jeas_0809_231.pdf</a></li>
<li><a href="http://www.antenna-theory.com/arrays/weights/lms.php">http://www.antenna-theory.com/arrays/weights/lms.php</a></li>
</ul></div>BEAM FORMINGhttp://www.blogger.com/profile/13948777650197565085noreply@blogger.com1tag:blogger.com,1999:blog-4036160346173961148.post-63792793131403692102011-10-04T10:08:00.001-04:002011-10-04T10:09:20.265-04:00Adaptive Filters [RLS,LMS]<div dir="ltr" style="text-align: left;" trbidi="on"><br />
<div>Follow the link for LMS and RLS </div><ul style="text-align: left;"><li><a href="http://www.spsc.tugraz.at/system/files/adaptivefilter.pdf">http://www.spsc.tugraz.at/system/files/adaptivefilter.pdf</a></li>
</ul></div>BEAM FORMINGhttp://www.blogger.com/profile/13948777650197565085noreply@blogger.com0tag:blogger.com,1999:blog-4036160346173961148.post-90572198982416420922011-10-03T15:09:00.009-04:002011-10-07T10:41:01.250-04:00Smart Antenna Technology—Beamforming<div dir="ltr" style="text-align: left;" trbidi="on"><span class="Apple-style-span" style="background-color: #e6ebee; font-family: Verdana, Arial, Helvatica, sans-serif; font-size: 11px; line-height: 14px;"></span><br />
<h3><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif; font-size: small;"><span class="Apple-style-span" style="font-weight: normal; line-height: 14px;"><div class="MsoNormal"><div style="color: #333333;"><br />
</div>There is an ever-increasing demand on mobile wireless operators to provide voice and high-speed data services. At the same time, these operators want to support more users per basestation to reduce overall network costs and make the services affordable to subscribers. As a result, wireless systems that enable higher data rates and higher capacities are a pressing need.<br />
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</div></span></span><span class="Apple-style-span" style="background-color: #e6ebee; line-height: 14px;"><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif; font-size: small;"><h3 style="line-height: normal;"><span class="Apple-style-span" style="font-weight: normal;"><span class="Apple-style-span" style="color: #b45f06;">Interference Limited Systems</span></span></h3><div style="font-weight: normal;">Unfortunately, because the available broadcast spectrum is limited, attempts to increase traffic within a fixed bandwidth create more interference in the system and degrade the signal quality.</div></span></span></h3><h3 style="line-height: normal;"><span class="Apple-style-span" style="color: #b45f06; font-family: Arial, Helvetica, sans-serif; font-size: small;">Smart Antenna Technology—Beamforming</span></h3><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">Smart antenna technology offers a significantly improved solution to reduce interference levels and improve the system capacity. With this technology, each user’s signal is transmitted and received by the basestation only in the direction of that particular user. This drastically reduces the overall interference in the system. A smart antenna system, as shown in Figure bellow, consists of an array of antennas that together direct different transmission/reception beams toward each user in the system. This method of transmission and reception is called beamforming and is made possible through smart (advanced) signal processing at the baseband.</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;"><br />
</span></div><div><strong><em><span class="Apple-style-span" style="color: #b45f06; font-family: Arial, Helvetica, sans-serif;">Smart Antenna System—Beamforming</span></em></strong></div><div style="color: #333333;"><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;"><img alt="Figure 2. Smart Antennas System—Beamforming" border="0" src="http://www.altera.com/end-markets/wireless/images/wir-beam_fig2.gif" style="border-bottom-width: 0px; border-color: initial; border-left-width: 0px; border-right-width: 0px; border-style: initial; border-top-width: 0px;" /></span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">In beamforming, each user’s signal is multiplied with complex weights that adjust the magnitude and phase of the signal to and from each antenna. This causes the output from the array of antennas to form a transmit/receive beam in the desired direction and minimizes the output in other directions.</span></div><h3 style="line-height: normal;"><span class="Apple-style-span" style="color: #b45f06; font-family: Arial, Helvetica, sans-serif; font-size: small;">Switched and Adaptive Beamforming</span></h3><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">If the complex weights are selected from a library of weights that form beams in specific, predetermined directions, the process is called switched beamforming. Here, the basestation basically switches between the different beams based on the received signal strength measurements. On the other hand, if the weights are computed and adaptively updated in real time, the process is called adaptive beamforming. Through adaptive beamforming, the basestation can form narrower beams towards the desired user and nulls towards interfering users, considerably improving the signal-to-interference-plus-noise ratio.</span><br />
<span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;"><br />
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<br />
<ul style="text-align: left;"><li><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;"><a href="http://www.pafkiet.edu.pk/LinkClick.aspx?fileticket=141bbnhm%2Fi0%3D&tabid=579&mid=2014"><span class="Apple-style-span" style="color: #b45f06;">http://www.pafkiet.edu.pk/LinkClick.aspx?fileticket=141bbnhm%2Fi0%3D&tabid=579&mid=2014</span></a></span></li>
</ul></div></div>BEAM FORMINGhttp://www.blogger.com/profile/13948777650197565085noreply@blogger.com0tag:blogger.com,1999:blog-4036160346173961148.post-31128539930859541062011-09-17T04:19:00.001-04:002011-09-17T04:20:05.824-04:00Least Mean-Square Error (LMS) Adaptive Weights<div dir="ltr" style="text-align: left;" trbidi="on"><pre><span style="color: green; font-size: x-large;"><strong><span style="color: #b45f06; font-family: Arial, Helvetica, sans-serif; font-size: small;">Least Mean-Square Error (LMS) Algorithm</span></strong></span></pre><ul style="text-align: left;"><li><a href="http://www.antenna-theory.com/arrays/weights/lms.php"><span style="color: #b45f06;">http://www.antenna-theory.com/arrays/weights/lms.php</span></a></li>
</ul></div>BEAM FORMINGhttp://www.blogger.com/profile/13948777650197565085noreply@blogger.com0tag:blogger.com,1999:blog-4036160346173961148.post-53615285575892723742011-08-15T11:59:00.005-04:002011-09-19T20:08:07.175-04:00BEAM FORMING<div dir="ltr" style="text-align: left;" trbidi="on"><div><div><span class="Apple-style-span" style="color: #b45f06; font-family: Arial, Helvetica, sans-serif;"><b>What is a Smart Antenna?</b></span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">The term “smart antenna” generally refers to any antenna array, terminated</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">in a sophisticated signal processor, which can adjust or adapt</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">its own beam pattern in order to emphasize signals of interest and to</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">minimize interfering signals.</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">Smart antennas generally encompass both switched beam and beamformed</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">adaptive systems. Switched beam systems have several available</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">fixed beam patterns. A decision is made as to which beam to</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">access, at any given point in time, based upon the requirements of</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">the system. Beamformed adaptive systems allow the antenna to steer</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">the beam to any direction of interest while simultaneously nulling</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">interfering signals. The smart antenna concept is opposed to the fixed</span></div></div><div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">beam “dumb antenna,” which does not attempt to adapt its radiation</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">pattern to an ever-changing electromagnetic environment. In the past,</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">smart antennas have alternatively been labeled adaptive arrays or digital</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">beamforming arrays. This new terminology reflects our penchant for</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">“smart” technologies and more accurately identifies an adaptive array</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">that is controlled by sophisticated signal processing. Figure 1.1 contrasts</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">two antenna arrays. The first is a traditional, fixed beam array</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">where the mainlobe can be steered, by defining the fixed array weights</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">w¯ . However, this configuration is neither smart nor adaptive.</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">The second array in the figure is a smart antenna designed to adapt to</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">a changing signal environment in order to optimize a given algorithm.</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">An optimizing criterion, or cost function, is normally defined based upon</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">the requirements at hand. In this example, the cost function is defined</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">as the magnitude of the error squared, |ε|2, between the desired signal</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">d and the array output y. The array weights w¯ are adjusted until the</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">output matches the desired signal and the cost function is minimized.</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">This results in an optimum radiation pattern.</span></div></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;"><br />
</span></div><div><div><span class="Apple-style-span" style="color: #b45f06; font-family: Arial, Helvetica, sans-serif;"><b>Why are Smart Antennas</b></span></div><div><span class="Apple-style-span" style="color: #b45f06; font-family: Arial, Helvetica, sans-serif;"><b>Emerging Now?</b></span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">The rapid growth in demand for smart antennas is fueled by two major</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">reasons. First, the technology for high speed analog-to-digital converters</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">(ADC) and high speed digital signal processing is burgeoning at an</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">alarming rate. Even though the concept of smart antennas has been</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">around since the late 50s [1–3], the technology required in order to</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">make the necessary rapid and computationally intense calculations has</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">only emerged recently. Early smart antennas, or adaptive arrays, were</span></div></div><div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">limited in their capabilities because adaptive algorithms were usually</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">implemented in analog hardware. With the growth of ADC and digital</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">signal processing (DSP); what was once performed in hardware</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">can now be performed digitally and quickly. ADCs, which have resolutions</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">that range from 8 to 24 bits, and sampling rates approaching</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">20 Gigasamples per second (GSa/s), are now a reality . In time,</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">superconducting data converters will be able to sample data at rates</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">up to 100 GSa/s [6]. This makes the direct digitization of most radio</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">frequency (RF) signals possible in many wireless applications. At the</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">very least, ADC can be applied to IF frequencies in higher RF frequency</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">applications. This allows most of the signal processing to be</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">defined in software near the front end of the receiver. In addition, DSP</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">can be implemented with high speed parallel processing using field</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">programmable gate arrays (FPGA). Current commercially available</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">FPGAs have speeds of up to 256 BMACS.1 Thus, the benefits of smart</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">antenna integration will only flourish, given the exponential growth in</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">the enabling digital technology continues.</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">Second, the global demand for all forms of wireless communication</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">and sensing continues to grow at a rapid rate. Smart antennas are</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">the practical realization of the subject of adaptive array signal processing</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">and have a wide range of interesting applications. These applications</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">include, but are not limited to, the following: mobile wireless</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">communications, software-defined radio [8, 9], wireless local</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">area networks (WLAN) , wireless local loops (WLL) , mobile</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">Internet, wireless metropolitan area networks (WMAN) , satellitebased</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">personal communications services, radar , ubiquitous radar</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">, many forms of remote sensing, mobile ad hoc networks (MANET)</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">, high data rate communications , satellite communications,</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">multiple-in-multiple-out (MIMO) systems , and waveform diversity</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">systems .</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">The rapid growth in telecommunications alone is sufficient to justify</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">the incorporation of smart antennas to enable higher system capacities</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">and data rates. It is projected that the United States will spend over</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">$137 billion on telecommunications in the year 2006. Global expenditures</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">on telecommunications are rapidly approaching $3 trillion.</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;"><br />
</span></div><div><span class="Apple-style-span" style="color: #b45f06;"><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;"><b> What are the Benefits </b></span><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;"><b>of Smart Antennas?</b></span></span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">Smart antennas have numerous important benefits in wireless applications</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">as well as in sensors such as radar. In the realm of mobile wireless</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">applications, smart antennas can provide higher system capacities by</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">1BMACS: Billion</span></div></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;"><br />
</span></div><div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">directing narrow beams toward the users of interest, while nulling other</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">users not of interest. This allows for higher signal-to-interference ratios,</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">lower power levels, and permits greater frequency reuse within the</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">same cell. This concept is called space division multiple access (SDMA).</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">In the United States, most base stations sectorize each cell into three</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">120◦ swaths as seen in Fig. 1.2a. This allows the system capacity to</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">potentially triple within a single cell because users in each of the three</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">sectors can share the same spectral resources. Most base stations can</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">be modified to include smart antennas within each sector. Thus the 120◦</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">sectors can be further subdivided as shown in Fig. 1.2b. This further</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">subdivision enables the use of lower power levels, and provides for even</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">higher system capacities and greater bandwidths.</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">Another benefit of smart antennas is that the deleterious effects of</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">multipath can be mitigated. As will be discussed in Chap. 8, a constant</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">modulus algorithm, which controls the smart antenna, can be</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">implemented in order to null multipath signals. This will dramatically</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">reduce fading in the received signal. Higher data rates can be realized</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">because smart antennas can simultaneously reduce both co-channel interference</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">and multipath fading. Multipath reduction not only benefits</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">mobile communications but also applies to many applications of radar</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">systems.</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">Smart antennas can be used to enhance direction-finding (DF) techniques</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">by more accurately finding angles-of-arrival (AOA) . A vast</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">array of spectral estimation techniques can be incorporated, which are</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">able to isolate the AOA with an angular precision that exceeds the resolution</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">of the array.</span><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">The </span><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">accurate estimation of AOA is especially beneficial in radar systems for</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">imaging objects or accurately tracking moving objects. Smart antenna</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">DF capabilities also enhance geo-location services enabling a wireless</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">system to better determine the location of a particular mobile user.</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">Additionally, smart antennas can direct the array main beam toward</span></div></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;"><br />
</span></div><div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">signals of interest even when no reference signal or training sequence</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">is available. This capability is called blind adaptive beamforming.</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">Smart antennas also play a role in MIMO communications systems</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">[18] and in waveform diverse MIMO radar systems [21, 22]. Since</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">diverse waveforms are transmitted from each element in the transmit</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">array and are combined at the receive array, smart antennas will play</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">a role in modifying radiation patterns in order to best capitalize on</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">the presence of multipath. With MIMO radar, the smart antenna can</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">exploit the independence between the various signals at each array element</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">in order to use target scintillation for improved performance, to</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">increase array resolution, and to mitigate clutter .</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">. In summary, let us list some of the numerous potential benefits</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">of smart antennas.</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">■ Improved system capacities</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">■ Higher permissible signal bandwidths</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">■ Space division multiple access (SDMA)</span></div></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">-Higher signal-to-interference ratios</span></div><div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">■ Increased frequency reuse</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">■ Sidelobe canceling or null steering</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">■ Multipath mitigation</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">■ Constant modulus restoration to phase modulated signals</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">■ Blind adaptation</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">■ Improved angle-of-arrival estimation and direction finding</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">■ Instantaneous tracking of moving sources</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">■ Reduced speckle in radar imaging</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">■ Clutter suppression</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">■ Increased degrees of freedom</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">■ Improved array resolution</span></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">■ MIMO compatibility in both communications and radar</span></div></div><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;"><br />
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</div></div>BEAM FORMINGhttp://www.blogger.com/profile/13948777650197565085noreply@blogger.com0tag:blogger.com,1999:blog-4036160346173961148.post-42692694161552355022011-08-10T11:35:00.003-04:002011-08-12T00:20:23.424-04:00Equalizer<div dir="ltr" style="text-align: left;" trbidi="on"><span class="Apple-style-span" style="background-color: white; line-height: 19px;"></span><br />
<div style="line-height: 1.5em; margin-bottom: 0.5em; margin-top: 0.4em;"><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">In telecommunication,the equalizer is a device that attempts to reverse the distortion incurred by a signal transmitted through a channel</span></div><div style="font-family: sans-serif; margin-bottom: 0.5em; margin-top: 0.4em;"><ul style="font-size: 19px; line-height: 1.5em; text-align: left;"></ul></div></div>BEAM FORMINGhttp://www.blogger.com/profile/13948777650197565085noreply@blogger.com0tag:blogger.com,1999:blog-4036160346173961148.post-64031058391563966432011-08-09T04:39:00.002-04:002011-08-28T00:42:06.810-04:00Selection Diversity<div dir="ltr" style="text-align: left;" trbidi="on"><span class="Apple-style-span" style="color: #111111; font-family: Arial, Helvetica, sans-serif;"><span class="Apple-style-span" style="font-size: 15px; line-height: 22px;">What is Selection Diversity?</span></span><br />
<span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;"><span class="Apple-style-span" style="font-size: 15px; line-height: 22px;">co</span></span>nsider a scenario where we have a single antenna for transmission and multiple antennas at the receiver (as shown in the figure below).<br />
<div style="margin-bottom: 1.467em; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px;"><img alt="" class="alignnone size-full wp-image-229" height="171" src="http://www.dsplog.com/db-install/wp-content/uploads/2008/09/receive_diversity.png" style="clear: both; display: block; margin-bottom: 1.467em; margin-left: 0px; margin-right: auto; margin-top: 0px; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px;" title="Receive Diversity" width="200" /></div><div style="margin-bottom: 1.467em; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px;"><strong style="margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px;">Figure: Receive diversity in a wireless link</strong></div><div style="margin-bottom: 1.467em; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px;">At the receiver we have now N copies of the same transmitted symbol. Which then poses the problem – how to effectively combine them to reliably recover the data.</div><div style="margin-bottom: 1.467em; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px;"><strong style="margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px;">Selection diversity</strong> approach is one way out – With <strong style="margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px;">selection diversity</strong>, the receiver selects the antenna with the highest received signal power and ignore observations from the other antennas. The chosen receive antenna is one which gives max signal power.</div></div>BEAM FORMINGhttp://www.blogger.com/profile/13948777650197565085noreply@blogger.com0tag:blogger.com,1999:blog-4036160346173961148.post-24059951347056174552011-08-09T03:32:00.002-04:002011-08-28T00:43:32.489-04:00Phased Array<div dir="ltr" style="text-align: left;" trbidi="on"><br />
<span class="Apple-style-span" style="font-family: arial, verdana, tahoma, sans-serif;">A phased arry antenna is composed of lots of radiating elements each with a phase shifter.Beams are formed by shifting the phase of the signal emitted from each radiating element,to provide constructive/destructive interference so as to steer the beams in the desired direction.</span><br />
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<div class="separator" style="clear: both; text-align: center;"><a href="http://www.radartutorial.eu/06.antennas/pic/interfer1.png" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img alt="The figure shows the interference of two one above the other lying in-phasely radiant antenna elements. The main beam direction is centric." border="0" height="140" src="http://www.radartutorial.eu/06.antennas/pic/interfer1.png" width="200" /></a><a href="http://www.radartutorial.eu/06.antennas/pic/interfer2.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img alt="The figure shows the interference of two one above the other lying antenna elements radiating with a different phase shift. The lower antenna element radiates with a phase shift of 15 degrees earlier as the upper antenna element. The main beam direction is steared up." border="0" height="140" src="http://www.radartutorial.eu/06.antennas/pic/interfer2.png" width="200" /></a></div><span class="Apple-style-span" style="background-color: #4c4c4c; color: #d9d9d9; font-family: arial, verdana, tahoma, sans-serif; font-size: 16px;"></span><br />
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<span class="Apple-style-span" style="font-family: arial, verdana, tahoma, sans-serif;">-Antenna elements fed with same phase -Fed with different phase shift</span><br />
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<span class="Apple-style-span" style="background-color: #4c4c4c; color: #d9d9d9;"><span class="Apple-style-span" style="background-color: white; color: black;"><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;"></span></span></span><br />
<span class="Apple-style-span" style="background-color: #4c4c4c; color: #d9d9d9;"><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">There are two basic types of smart antennas. As shown in Fig below the first type is the phased array or multibeam antenna, which consists of either a number of fixed beams with one beam turned on towards the desired signal or a single beam (formed by phase adjustment only) that is steered toward the desired signal. The other type is the adaptive antenna array as shown in Fig. which is an array of multiple antenna elements, with the received signals weighted and combined to maximize the desired signal to interference plus noise power ratio. This essentially puts a main beam in the direction of the desired signal and nulls in the direction of the interference.</span></span><br />
<span class="Apple-style-span" style="background-color: #4c4c4c; color: #d9d9d9;"><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">A smart antenna is therefore a phased or adaptive array that adjusts to the environment. That is, for the adaptive array, the beam pattern changes as the desired user and the interference move; and for the phased array the beam is steered or different beams are selected as the desired user moves.</span></span><br />
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<li><a href="http://mobiledevdesign.com/tutorials/ofdm/"><span class="Apple-style-span" style="color: #b45f06;">http://mobiledevdesign.com/tutorials/ofdm/</span></a></li>
<li><a href="http://www.conniq.com/WiMAX/fdm-ofdm-ofdma-sofdma-01.htm"><span class="Apple-style-span" style="color: #b45f06;">http://www.conniq.com/WiMAX/fdm-ofdm-ofdma-sofdma-01.htm</span></a></li>
<li><a href="http://netlab18.cis.nctu.edu.tw/html/wlan_course/powerpoint/chap-11.pdf"><span class="Apple-style-span" style="color: #b45f06;">http://netlab18.cis.nctu.edu.tw/html/wlan_course/powerpoint/chap-11.pdf</span></a></li>
<li><a href="http://xa.yimg.com/kq/groups/24541321/430902680/name/OFDM%20in%20WiMAX.pdf"><span class="Apple-style-span" style="color: #b45f06;">http://xa.yimg.com/kq/groups/24541321/430902680/name/OFDM%20in%20WiMAX.pdf</span></a></li>
</ul></div>BEAM FORMINGhttp://www.blogger.com/profile/13948777650197565085noreply@blogger.com0tag:blogger.com,1999:blog-4036160346173961148.post-5952349985077934802011-07-28T10:27:00.007-04:002011-08-08T12:59:09.566-04:00Transmit Beamforming<div dir="ltr" style="text-align: left;" trbidi="on"><div><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">Transmit beamforming is a method of transmitting two or more phase-shifted signals so that they will be in-phase at particular points in space where the transmitter believes the receiver to be, thereby increasing SNR.</span></div><ul style="text-align: left;"><li><a href="ftp://ftp.dlink.fr/Windows_Seven/White%20Paper%20by%20Ralink%20on%20802.11n%20Radio%20Beamforming%20technology.pdf"><span class="Apple-style-span" style="color: #b45f06;">ftp://ftp.dlink.fr/Windows_Seve<span></span>n/White%20Paper%20by%20Ralink%20on%20802.11n%20Radio%20Beamforming%20technology.pdf</span></a></li>
<li><a href="http://www.spectrumsignal.com/publications/beamform_primer.pdf"><span class="Apple-style-span" style="color: #b45f06;">http://www.spectrumsignal.com/publications/beamform_primer.pdf</span></a></li>
</ul></div>BEAM FORMINGhttp://www.blogger.com/profile/13948777650197565085noreply@blogger.com2tag:blogger.com,1999:blog-4036160346173961148.post-38357440018279555032011-07-27T13:31:00.000-04:002011-07-27T13:31:21.042-04:00Various Beamformer Structures Used In Smart Antennas<div dir="ltr" style="text-align: left;" trbidi="on"><br />
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</div><ul style="text-align: left;"><li><span class="Apple-style-span" style="color: #b45f06;"><a href="http://omidi.iut.ac.ir/SDR/2007/WebPages/07_SmartAntenna/pages/sdr.html">http://omidi.iut.ac.ir/SDR/2007/WebPages/07_SmartAntenna/pages/sdr.html</a></span></li>
</ul></div>BEAM FORMINGhttp://www.blogger.com/profile/13948777650197565085noreply@blogger.com0tag:blogger.com,1999:blog-4036160346173961148.post-79020587850148770912011-07-26T13:56:00.002-04:002011-07-26T14:01:32.284-04:00Fixed Beam Forming Techniques<div dir="ltr" style="text-align: left;" trbidi="on"><br />
<span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">Fixed Beam Forming Techniques</span><br />
<span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">Some array applications require several fixed beams that cover an angular sector.</span><br />
<span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">Several beam forming techniques exist that provide these fixed beams. Three examples</span><br />
<span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">are given here.</span><br />
<span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;"><b> Butler matrix </b>The Butler matrix is a beam forming network that uses a</span><br />
<span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">combination of 90° hybrids and phase shifters. An 8x8 Butler matrix is shown in Fig 3-5.</span><br />
<span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">The Butler matrix performs a spatial fast Fourier transform and provides 2n orthogonal</span><br />
<span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">beams. These beams are linearly independent combinations of the array element patterns</span><br />
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<span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">When used with a linear array the Butler matrix produces beams that overlap at</span><br />
<span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">about 3.9 dB below the beam maxima. A Butler matrix-fed array can cover a sector of up</span><br />
<span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">to 360° depending on element patterns and spacing. Each beam can be used by a</span><br />
<span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">dedicated transmitter and/or receiver, or a single transmitter and/or receiver can be used,</span><br />
<span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">and the appropriate beam can be selected using an RF switch. A Butler matrix can also</span><br />
<span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">be used to steer the beam of a circular array by exciting the Butler matrix beam ports with</span><br />
<span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">amplitude and phase weighted inputs followed by a variable uniform phase taper.</span><br />
<span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;"><a href="http://scholar.lib.vt.edu/theses/available/etd-04262000-15330030/unrestricted/ch3.pdf"><span class="Apple-style-span" style="color: #b45f06;">http://scholar.lib.vt.edu/theses/available/etd-04262000-15330030/unrestricted/ch3.pdf</span></a></span></div>BEAM FORMINGhttp://www.blogger.com/profile/13948777650197565085noreply@blogger.com0tag:blogger.com,1999:blog-4036160346173961148.post-54215758333127412742011-07-25T12:59:00.002-04:002011-07-25T14:01:33.107-04:00Phased Array<div dir="ltr" style="text-align: left;" trbidi="on"><span class="Apple-style-span" style="font-family: sans-serif; font-size: 13px; line-height: 19px;">In<span class="Apple-style-span" style="color: #b45f06;"> <a class="mw-redirect" href="http://en.wikipedia.org/wiki/Wave_theory" style="background-attachment: initial; background-clip: initial; background-color: initial; background-image: none; background-origin: initial; text-decoration: none;" title="Wave theory"><span class="Apple-style-span" style="color: #b45f06;">wave theory</span></a>,</span> a <b>phased array</b> is a group of<span class="Apple-style-span" style="color: #b45f06;"> <a class="mw-redirect" href="http://en.wikipedia.org/wiki/Antenna_(electronics)" style="background-attachment: initial; background-clip: initial; background-color: initial; background-image: none; background-origin: initial; text-decoration: none;" title="Antenna (electronics)"><span class="Apple-style-span" style="color: #b45f06;">antennas</span></a></span> in which the relative <a href="http://en.wikipedia.org/wiki/Phase_(waves)" style="background-attachment: initial; background-clip: initial; background-color: initial; background-image: none; background-origin: initial; text-decoration: none;" title="Phase (waves)"><span class="Apple-style-span" style="color: #b45f06;">phases</span></a> of the respective<span class="Apple-style-span" style="color: #b45f06;"> <a class="mw-redirect" href="http://en.wikipedia.org/wiki/Signaling_(telecommunication)" style="background-attachment: initial; background-clip: initial; background-color: initial; background-image: none; background-origin: initial; text-decoration: none;" title="Signaling (telecommunication)"><span class="Apple-style-span" style="color: #b45f06;">signals</span></a></span> feeding the antennas are varied in such a way that the effective <a href="http://en.wikipedia.org/wiki/Radiation_pattern" style="background-attachment: initial; background-clip: initial; background-color: initial; background-image: none; background-origin: initial; text-decoration: none;" title="Radiation pattern"><span class="Apple-style-span" style="color: #b45f06;">radiation pattern</span></a> of the array is reinforced in a desired direction and suppressed in undesired directions</span><br />
<span class="Apple-style-span" style="font-family: sans-serif; font-size: 13px; line-height: 19px;"><br />
</span><br />
<span class="Apple-style-span" style="color: #b45f06; font-family: sans-serif; font-size: 19px; line-height: 19px;">Different types of phased arrays</span><br />
<span class="Apple-style-span" style="font-family: sans-serif; font-size: 13px; line-height: 19px;"></span><br />
<div style="line-height: 1.5em; margin-bottom: 0.5em; margin-left: 0px; margin-right: 0px; margin-top: 0.4em;">There are two main different types of phased arrays, also called beamformers. There are <a href="http://en.wikipedia.org/wiki/Time_domain" style="background-attachment: initial; background-clip: initial; background-color: initial; background-image: none; background-origin: initial; background-position: initial initial; background-repeat: initial initial; color: #0645ad; text-decoration: none;" title="Time domain">time domain</a>beamformers and <a href="http://en.wikipedia.org/wiki/Frequency_domain" style="background-attachment: initial; background-clip: initial; background-color: initial; background-image: none; background-origin: initial; background-position: initial initial; background-repeat: initial initial; color: #0645ad; text-decoration: none;" title="Frequency domain">frequency domain</a> beamformers.</div><div style="line-height: 1.5em; margin-bottom: 0.5em; margin-left: 0px; margin-right: 0px; margin-top: 0.4em;">A time domain beamformer works, as the name says, by doing time-based operations. The basic operation is called "delay and sum". It delays the incoming signal from each array element by a certain amount of time, and then adds them together. Sometimes a multiplication with a window across the array is done to increase the mainlobe/sidelobe ratio, and to insert zeroes in the characteristic.</div><div style="line-height: 1.5em; margin-bottom: 0.5em; margin-left: 0px; margin-right: 0px; margin-top: 0.4em;">There are two different types of frequency domain beamformers. The first type separates the different frequency components that are present in the received signal into different frequency bins (using either an <a class="mw-redirect" href="http://en.wikipedia.org/wiki/FFT" style="background-attachment: initial; background-clip: initial; background-color: initial; background-image: none; background-origin: initial; background-position: initial initial; background-repeat: initial initial; color: #0645ad; text-decoration: none;" title="FFT">FFT</a> or a <a class="mw-redirect" href="http://en.wikipedia.org/wiki/Filterbank" style="background-attachment: initial; background-clip: initial; background-color: initial; background-image: none; background-origin: initial; background-position: initial initial; background-repeat: initial initial; color: #0645ad; text-decoration: none;" title="Filterbank">filterbank</a>). When different delay and sum beamformers are applied to each frequency bin, it is possible to point the main lobe to different directions for different frequencies. This can be an advantage for communication links.</div><div style="line-height: 1.5em; margin-bottom: 0.5em; margin-left: 0px; margin-right: 0px; margin-top: 0.4em;">The other type of frequency domain beamformers makes use of so called Spatial Frequency. This means that an FFT is taken across the different array elements, not in time. The output of the N point FFT are N channels, which are evenly divided in space. This approach makes a simple implementation of several beamformers at the same time possible, but this approach is not flexible, because the different directions are fixed.</div><div style="line-height: 1.5em; margin-bottom: 0.5em; margin-left: 0px; margin-right: 0px; margin-top: 0.4em;"><br />
</div><div style="line-height: 1.5em; margin-bottom: 0.5em; margin-left: 0px; margin-right: 0px; margin-top: 0.4em;"><br />
</div><div style="line-height: 1.5em; margin-bottom: 0.5em; margin-left: 0px; margin-right: 0px; margin-top: 0.4em;"><a href="http://www.antenna-theory.com/arrays/main.php">http://www.antenna-theory.com/arrays/main.php</a></div></div>BEAM FORMINGhttp://www.blogger.com/profile/13948777650197565085noreply@blogger.com0tag:blogger.com,1999:blog-4036160346173961148.post-71722036988579581232011-07-22T09:33:00.000-04:002011-07-22T09:33:32.087-04:00Multiplexing gain vs Diversity gain<div dir="ltr" style="text-align: left;" trbidi="on"><br />
<br />
<ul style="text-align: left;"><li><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;"><span class="Apple-style-span" style="color: #b45f06;"><b>Multiplexing gain:</b></span> different signals sent through different parallel channels, leading to the</span></li>
</ul><br />
<span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">information transmission rate increase;</span><br />
<br />
<ul style="text-align: left;"><li><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;"><span class="Apple-style-span" style="color: #b45f06;"><b> Diversity gain:</b></span> the same signals sent through different parallel channels, leading to the BER</span></li>
</ul><br />
<span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">improvement</span><br />
</div>BEAM FORMINGhttp://www.blogger.com/profile/13948777650197565085noreply@blogger.com0tag:blogger.com,1999:blog-4036160346173961148.post-15330604143800872142011-07-22T08:47:00.001-04:002011-07-22T09:07:04.285-04:00<div dir="ltr" style="text-align: left;" trbidi="on"><br />
Principles of Transmit Beamforming<br />
The basic principle of transmit beamforming is to maximize the received Signal to<br />
Noise Ratio (SNR) at the intended destination. It is a general signal processing technique<br />
used to control the directionality of the transmission of a signal on a transducer array. A<br />
transmit beamformer itself is a spatial filter that operates on the output of an array of<br />
sensors in order to enhance the amplitude of a coherent wavefront relative to background<br />
noise and directional interference.<br />
<br />
<br />
Energy Gains of Transmit Beamforming<br />
The question of how is directional transmission achieved is of particular importance. In<br />
beamforming, each user’s signal is multiplied with complex weights that adjust the<br />
magnitude and phase of the signal to and from each antenna. This causes the output from<br />
the array of antennas to form a transmit beam in the desired direction and minimizes the<br />
output in other directions. This directionality provides a strong energy gain observed at<br />
the destination.<br />
<br />
</div>BEAM FORMINGhttp://www.blogger.com/profile/13948777650197565085noreply@blogger.com0tag:blogger.com,1999:blog-4036160346173961148.post-28189773525190112802011-07-17T08:37:00.000-04:002011-07-17T08:37:03.774-04:00Singular Value Decomposition<b><span class="Apple-style-span" style="color: #b45f06; font-family: Arial, Helvetica, sans-serif;">What is Singular Value Decomposition</span></b>?<div><div style="line-height: 18px; margin-bottom: 0.5em; margin-left: 1.4ex; margin-right: 20%; margin-top: 0.5em; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px;"><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">Singular value decomposition (SVD) is a means of decomposing a a matrix into a product of three simpler matrices. In this way it is related to other matrix decompositions such as eigen decomposition, principal components analysis (PCA), and non-negative matrix factorization (NNMF).</span></div><div style="line-height: 18px; margin-bottom: 0.5em; margin-left: 1.4ex; margin-right: 20%; margin-top: 0.5em; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px;"><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;"><a href="http://alias-i.com/lingpipe/demos/tutorial/svd/read-me.html">http://alias-i.com/lingpipe/demos/tutorial/svd/read-me.html</a></span></div><div style="font-family: verdana, arial, sans-serif; font-size: 14px;"><br />
</div></div><div><br />
</div>BEAM FORMINGhttp://www.blogger.com/profile/13948777650197565085noreply@blogger.com0tag:blogger.com,1999:blog-4036160346173961148.post-763519559755268262011-07-16T20:53:00.003-04:002011-07-16T21:26:34.056-04:00Optimum Signal Processing<ul><li><a href="http://www.ece.rutgers.edu/~orfanidi/ece525/">http://www.ece.rutgers.edu/~orfanidi/ece525/</a></li>
</ul><br />
In PDF format<br />
<br />
<ul><li><a href="http://www.ece.rutgers.edu/~orfanidi/osp2e/osp2e.pdf">http://www.ece.rutgers.edu/~orfanidi/osp2e/osp2e.pdf</a><br />
Beamforming</li>
<li><a href="http://www.comm.utoronto.ca/~rsadve/Notes/BeamForming.pdf">http://www.comm.utoronto.ca/~rsadve/Notes/BeamForming.pdf</a></li>
</ul>BEAM FORMINGhttp://www.blogger.com/profile/13948777650197565085noreply@blogger.com0tag:blogger.com,1999:blog-4036160346173961148.post-75684577600663280822011-07-15T13:32:00.002-04:002011-07-15T13:34:00.077-04:00Diversity combining<span class="Apple-style-span" style="font-family: sans-serif; font-size: 13px; line-height: 19px;"><b>Diversity combining</b> is the technique applied to combine the multiple received signals of a <span class="Apple-style-span" style="background-attachment: initial; background-clip: initial; background-color: initial; background-image: none; background-origin: initial; color: #b45f06; text-decoration: none;"><a href="http://en.wikipedia.org/wiki/Diversity_scheme" style="background-attachment: initial; background-clip: initial; background-color: initial; background-image: none; background-origin: initial; text-decoration: none;" title="Diversity scheme">diversity</a> </span>reception device into a single improved signal.</span><br />
<span class="Apple-style-span" style="font-family: sans-serif; font-size: 13px; line-height: 19px;"><br />
</span><br />
<span class="Apple-style-span" style="font-family: sans-serif; font-size: 13px; line-height: 19px;"></span><br />
<div style="line-height: 1.5em; margin-bottom: 0.5em; margin-left: 0px; margin-right: 0px; margin-top: 0.4em;">Various diversity combining techniques can be distinguished: </div><ul style="line-height: 1.5em; list-style-image: url(data:image/png; list-style-type: square; margin-bottom: 0.5em; margin-left: 1.6em; margin-right: 0px; margin-top: 0.3em; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px;"><li style="margin-bottom: 0.1em;"><span class="Apple-style-span" style="color: #b45f06;">Selection combining:</span> Of the N received signals, the strongest signal is selected</li>
<li style="margin-bottom: 0.1em;"><span class="Apple-style-span" style="color: #b45f06;"><a class="new" href="http://en.wikipedia.org/w/index.php?title=Switched_combining&action=edit&redlink=1" style="background-attachment: initial; background-clip: initial; background-color: initial; background-image: none; background-origin: initial; text-decoration: none;" title="Switched combining (page does not exist)"><span class="Apple-style-span" style="color: #b45f06;">Switched combining</span></a>: </span>The receiver switches to another signal when current signal drops below a predefined threshold. This is a less efficient technique than selection combining.</li>
<li style="margin-bottom: 0.1em;"><a class="new" href="http://en.wikipedia.org/w/index.php?title=Equal_gain_combining&action=edit&redlink=1" style="background-attachment: initial; background-clip: initial; background-color: initial; background-image: none; background-origin: initial; background-position: initial initial; background-repeat: initial initial; color: #ba0000; text-decoration: none;" title="Equal gain combining (page does not exist)">Equal </a><span class="Apple-style-span" style="color: #b45f06;"><a class="new" href="http://en.wikipedia.org/w/index.php?title=Equal_gain_combining&action=edit&redlink=1" style="background-attachment: initial; background-clip: initial; background-color: initial; background-image: none; background-origin: initial; text-decoration: none;" title="Equal gain combining (page does not exist)"><span class="Apple-style-span" style="color: #b45f06;">gain</span> <span class="Apple-style-span" style="color: #b45f06;">combining</span></a>: </span>All the received signals are summed coherently.</li>
<li style="margin-bottom: 0.1em;"><a href="http://en.wikipedia.org/wiki/Maximal-ratio_combining" style="background-attachment: initial; background-clip: initial; background-color: initial; background-image: none; background-origin: initial; text-decoration: none;" title="Maximal-ratio combining"><span class="Apple-style-span" style="color: #b45f06;">Maximal</span></a><a href="http://en.wikipedia.org/wiki/Maximal-ratio_combining" style="background-attachment: initial; background-clip: initial; background-color: initial; background-image: none; background-origin: initial; text-decoration: none;" title="Maximal-ratio combining"><span class="Apple-style-span" style="color: #b45f06;">-ratio combining</span></a> is often used in large <a href="http://en.wikipedia.org/wiki/Phased_array" style="background-attachment: initial; background-clip: initial; background-color: initial; background-image: none; background-origin: initial; text-decoration: none;" title="Phased array"><span class="Apple-style-span" style="color: #b45f06;">phased array</span></a> systems: The received signals are weighted with respect to their <a href="http://en.wikipedia.org/wiki/Signal-to-noise_ratio" style="background-attachment: initial; background-clip: initial; background-color: initial; background-image: none; background-origin: initial; text-decoration: none;" title="Signal-to-noise ratio"><span class="Apple-style-span" style="color: #b45f06;">SNR</span></a> and then summed.</li>
</ul>BEAM FORMINGhttp://www.blogger.com/profile/13948777650197565085noreply@blogger.com0tag:blogger.com,1999:blog-4036160346173961148.post-52060269764751394782011-07-15T12:33:00.002-04:002011-07-24T02:37:49.830-04:00BEAMFORMING<div dir="ltr" style="text-align: left;" trbidi="on"><div class="separator" style="clear: both; margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px; text-align: left;"><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;"><span class="Apple-style-span" style="color: #666666;"> <br />
<strong>Beamforming</strong> is a general signal processing technique used to control the directionality of the reception or transmission of a signal on a transducer array.<br />
<br />
Using beamforming you can direct the majority of signal energy you transmit from a group of transducers (like audio speakers or radio antennae) in a chosen angular direction. Or you can calibrate your group of transducers when receiving signals such that you predominently receive from a chosen angular direction. The physics and math are essentially the same for both the transmitting and receiving cases.</span><span class="Apple-style-span"><br />
<b><br />
</b></span></span></div><div style="margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px;"><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;"><span class="Apple-style-span" style="line-height: 20px;"> </span><span class="Apple-style-span" style="line-height: 20px;"> Follow the links for Beamforming & Smart Antennas:</span></span></div><div style="margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px;"><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;"><br />
</span></div><ul><li><span class="Apple-style-span" style="color: #b45f06;"><span class="Apple-style-span" style="line-height: 20px;"><a href="http://www.blogger.com/goog_1440772947"><span class="Apple-style-span" style="color: #b45f06; font-family: Arial, Helvetica, sans-serif;">http://www.altera.com/end-markets/wireless/advanced-dsp/beamforming/wir-beamforming</span></a></span></span></li>
<li><a href="http://www.waset.org/journals/waset/v19/v19-33.pdf"><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;"><span class="Apple-style-span" style="color: #b45f06;">http://www.waset.org/journals/waset/v19</span><span class="Apple-style-span" style="color: #b45f06;">/v19-33.pdf</span></span></a></li>
</ul><div style="margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px;"><br />
</div></div>BEAM FORMINGhttp://www.blogger.com/profile/13948777650197565085noreply@blogger.com0tag:blogger.com,1999:blog-4036160346173961148.post-43369098319990974532011-07-15T12:29:00.001-04:002011-07-15T12:42:01.852-04:00Channel coding<div style="line-height: 1.4;"><div style="margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px;"><span class="Apple-style-span" style="color: #b45f06; font-family: inherit;"><b>Coding</b></span></div><div style="margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px;"><strong style="font-family: inherit;"> </strong><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">Before sending bits to the channel, they are usually somehow coded. By coding the bits we want to make it easier for the receiver to localize errors which are likely to occur during our transmission (the most easy case to understand is the additive noise added by the channel). It is actually also possible to correct some of these errors. </span></div></div><div style="line-height: 1.4;"><div style="margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px;"><span class="Apple-style-span" style="color: #b45f06; font-family: Arial, Helvetica, sans-serif;"><strong>Decoding</strong></span></div><div style="margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px;"><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">If we code, we of course have also to decode in order to get the original information back. When you read about decoding techniques you will find Hard Decoding and Soft Decoding. explanation. </span></div><div style="margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px;"><strong><span class="Apple-style-span" style="color: #b45f06; font-family: Arial, Helvetica, sans-serif;">Useful concepts: </span></strong></div></div><div style="line-height: 1.4;"><div style="margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px;"><span class="Apple-style-span" style="font-family: inherit;">I</span><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">t is important to understand what Hamming Distance and Euclidean Distance mean, especially applied to vectors. You can have a look at the following links:</span></div></div><div style="line-height: 1.4;"><div style="margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px;"><br />
<ul><li><a href="http://en.wikipedia.org/wiki/Hamming_distance"><span class="Apple-style-span" style="color: #b45f06;">http://en.wikipedia.org/wiki/Hamming_distance</span></a></li>
<li><span class="Apple-style-span" style="color: #b45f06;"><a href="http://en.wikipedia.org/wiki/Euclidean_distance"><span class="Apple-style-span" style="color: #b45f06;">http://en.wikipedia.org/wiki/Euclidean_distance</span></a></span></li>
</ul></div></div><div><div style="margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px;"><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif; line-height: 22px;">Follow the link for Convolutional coding:</span></div></div><div style="line-height: 1.4;"><ul><li><span class="Apple-style-span" style="color: #b45f06;"><a href="http://www.comlab.hut.fi/opetus/333/2004_2005_slides/Convolutional_Coding_Viterbi_Algorithm.pdf">http://www.comlab.hut.fi/opetus/333/2004_2005_slides/Convolutional_Coding_Viterbi_Algorithm.pdf</a></span><span class="Apple-style-span" style="font-family: Arial, Helvetica, sans-serif;">Follow the link for Reed Solmon and Convolutional coding:</span></li>
</ul><ul><li><span class="Apple-style-span" style="color: #b45f06;"><a href="http://www.highlandcomm.com/reed_solomon_codes.htm">http://www.highlandcomm.com/reed_solomon_codes.htm</a></span></li>
<li><span class="Apple-style-span" style="line-height: normal;"><a href="http://www.complextoreal.com/convo.htm">http://www.complextoreal.com/convo.htm</a></span></li>
</ul></div>BEAM FORMINGhttp://www.blogger.com/profile/13948777650197565085noreply@blogger.com0tag:blogger.com,1999:blog-4036160346173961148.post-22700479177451319682011-07-14T03:08:00.002-04:002011-08-28T00:55:58.182-04:00Beamforming Techniques for OFDM<div dir="ltr" style="text-align: left;" trbidi="on"><div><br />
</div><ul><li><span class="Apple-style-span" style="color: #b45f06;"><a href="http://www.mprg.org/research/OFDM/ofdm_beamforming.html"><span class="Apple-style-span" style="color: #b45f06;">http://www.mprg.org/research/OFDM/ofdm_beamforming.html</span></a></span></li>
<li><a href="http://www.ece.uci.edu/~ayanoglu/ICC05.pdf"><span class="Apple-style-span" style="color: #b45f06;">http://www.ece.uci.edu/~ayanoglu/ICC05.pdf</span></a></li>
<li><a href="http://userspages.uob.edu.bh/mangoud/paper3.pdf"><span class="Apple-style-span" style="color: #b45f06;">http://userspages.uob.edu.bh/mangoud/paper3.pdf</span></a></li>
</ul></div>BEAM FORMINGhttp://www.blogger.com/profile/13948777650197565085noreply@blogger.com0tag:blogger.com,1999:blog-4036160346173961148.post-57182290680164784922011-07-13T13:06:00.000-04:002011-07-15T04:15:57.928-04:00Beamforming Boosts the Range and Capacity of WiMAX Networks<ul><li><span class="Apple-style-span" style="color: #b45f06;">http://www.fujitsu.com/downloads/MICRO/fma/form</span>p<span class="Apple-style-span" style="color: #b45f06;">df/WiMAXbeamform.pdf</span></li>
<li><a href="http://www.sequans.com/pdf/mimo_whitepaper.pdf">http://www.sequans.com/pdf/mimo_whitepaper.pdf</a></li>
<li><a href="http://www.commscope.com/andrew/eng/product/antennas/bsa/bsa_tech_info/Performance_Evaluation_%20MIMO_Base_Station_Antenna_Designs.pdf">http://www.commscope.com/andrew/eng/product/antennas/bsa/bsa_tech_info/Performance_Evaluation_%20MIMO_Base_Station_Antenna_Designs.pdf</a></li>
</ul>BEAM FORMINGhttp://www.blogger.com/profile/13948777650197565085noreply@blogger.com0tag:blogger.com,1999:blog-4036160346173961148.post-67309853289199054182011-07-13T01:08:00.002-04:002011-08-13T04:09:56.690-04:00MATLAB codes of a Smart Antenna System<div dir="ltr" style="text-align: left;" trbidi="on"><div><br />
</div><ul><li><span class="Apple-style-span" style="color: #b45f06;"><a href="http://en.pudn.com/downloads113/sourcecode/math/detail473089_en.html">http://en.pudn.com/downloads113/sourcecode/math/detail473089_en.html</a></span></li>
</ul></div>BEAM FORMINGhttp://www.blogger.com/profile/13948777650197565085noreply@blogger.com0