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Chen, Kang; Randy Oltman,; Michael McKernan,. "Mobility testing for beamforming base stations.(WIRELESS TEST)." EE-Evaluation Engineering. NP Communications, LLC. 2008. HighBeam Research. 25 Apr. 2018 <https://www.highbeam.com>.
Chen, Kang; Randy Oltman,; Michael McKernan,. "Mobility testing for beamforming base stations.(WIRELESS TEST)." EE-Evaluation Engineering. 2008. HighBeam Research. (April 25, 2018). https://www.highbeam.com/doc/1G1-183750335.html
Chen, Kang; Randy Oltman,; Michael McKernan,. "Mobility testing for beamforming base stations.(WIRELESS TEST)." EE-Evaluation Engineering. NP Communications, LLC. 2008. Retrieved April 25, 2018 from HighBeam Research: https://www.highbeam.com/doc/1G1-183750335.html
The continuing goal in today's data-centric wireless technology is to improve data rates and fidelity in the most cost-efficient way. Recent advances in antenna technology have introduced wide-scale deployment of antenna arrays used in multiple-in, multiple-out (MIMO) configurations.
Next-generation wireless technologies such as WiMAX. Long-Term Evolution (LTE) and Ultra Mobile Broadband (UMB) all make use of multiple-antenna-array technologies. Now they also can utilize beamforming, a more advanced technique.
Beamforming is a signal-processing technique that requires estimating channel information and adaptively shaping beams to enhance some signals and suppress others. To implement beamforming, three basic techniques are used: adaptive beam steering, maximum ratio transmission (MRT), and Eigen beamforming (EBF).
Adaptive beam steering can be implemented when the mobile device has a single antenna; MRT and EBT are MIMO beamforming techniques. All three methods can dynamically adjust the relative amplitude and phase, the antenna weights, on each element of the base-station antenna array. Table 1 compares and contrasts the three approaches.
Table 1. Beamforming Techniques Beamforming Technique Channel Characteristics Notes Adaptive Beam Steering LOS or small angular High gain for single spread, very high user but ineffective correlation in environments that cause high angular spread Maximum Ratio High SNR, low velocity, Maximum SNR but Transmission large angular spread, requires frequent high correlation channel measurements and is computationally intensive Eigen Beamforming Low SNR or high Robust in high-speed velocity, mobility but offers high correlation less beamforming gain than MRT
The result is that lobes of constructive interference or beams can be created and steered on the transmitted link. On the received link, beams can be created and aimed toward desired users while nulls can be steered toward sources of unwanted interference. Figure 1 shows the basic concept of a beamforming system.
[FIGURE 1 OMITTED]
Adaptive Beam Steering
In single-user-antenna beamforming, the mobile device periodically sends a channel sounding signal. Each base-station antenna element receives this signal at a slightly different phase offset and amplitude so that algorithms can estimate direction-of-arrival (DoA) for each user based on a unique spatial signature. …
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