MIMO and Smart Antennas for Mobile Broadband ... - 4G Americas
MIMO and Smart Antennas for Mobile Broadband ... - 4G Americas
MIMO and Smart Antennas for Mobile Broadband ... - 4G Americas
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It is evident from the trial that <strong>MIMO</strong> per<strong>for</strong>ms very well with h<strong>and</strong>held devices also at lower carrierfrequencies. However, <strong>MIMO</strong> per<strong>for</strong>mance will be very poor if the antenna system is not designedtargeting low correlation properties. Device SP2 had much lower per<strong>for</strong>mance than the other devices <strong>and</strong>the dual dipole antenna reference set-up due to the design of SP2 giving intentionally high antennabranch signal correlation. This is shown in both its low ability to select rank 2 <strong>MIMO</strong>-transmission <strong>and</strong> inthe throughput figures.The trials also showed that the effect on <strong>MIMO</strong> per<strong>for</strong>mance with h<strong>and</strong>s holding the device was relativelylarge with certain antenna designs. This further emphasizes the importance of a careful antenna design.The effect of device placement inside the test vehicle was mainly loss of signal strength. Such loss maybe very significant in a power limited scenario. The same applies to antenna efficiency. The majority ofthe tested cases were not mainly power limited rather interference limited, <strong>and</strong> hence the effect of the invanplacement on throughput was relatively small. However, note that the body style of the vehicle wasprobably an important aspect when characterizing the in-vehicle radio channel, hence results obtainedmay only be valid <strong>for</strong> the type used in the trials, i.e., a panel truck with no windows behind the in-v<strong>and</strong>evices.7.3 CURRENT STATUS OF TERMINAL ANTENNASMultiple antennas are currently found in the terminals of many wireless products, particularly PCs, datacards, <strong>and</strong> USB dongles. See <strong>for</strong> example, the products whose antennas are photographed below inFigure 111 through Figure 113 below.Of course, terminals are not just h<strong>and</strong>sets anymore. <strong>Mobile</strong> terminals such as the Kindle <strong>and</strong> iPad, not tomention laptops <strong>and</strong> notebooks that have integrated UT built in have a great deal of room <strong>for</strong> multipleantennas. Beyond the FM radio antenna, GPS receiver, WiFi <strong>and</strong> multiple b<strong>and</strong> antennas, they also nowsupport multiple antennas as well.<strong>4G</strong> <strong>Americas</strong> <strong>MIMO</strong> <strong>and</strong> <strong>Smart</strong> <strong>Antennas</strong> <strong>for</strong> <strong>Mobile</strong> Systems – October 2012 – All Rights Reserved125
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