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4. Beam forming Antenna: Beamforming is a spatial signal processing technique for directional signal transmission or reception. It is achieved by intentionally controlling the phase and relative amplitude on the same signal at each antenna by a beamformer. A beamformer amplifies the transmitted/received signals in one direction than others. Pointed beams directed towards users improves the received signal quality and reduces inter and intra-cell interference due to directional signal transmission. Transmit and receive beamforming power gain, coupled with reduced interference, boosts signal-to-interference-plus-noise ratio (SINR), bringing higher data rates, more cellular capacity, and improve cell coverage.
Figure 5: Beamforming
Challenges
• Free Space Pathloss: The mmWave suffer higher pathloss relative to lower frequencies, thus limiting the range. For the same distance, compared to 1 GHz, the free space pathloss at 28 GHz is approximately 29 dB higher. While at 38 GHz, the free space pathloss is approximately 32 dB higher • Blockage (Shadowing Effects): mmWave signals tend to be more sensitive to obstacles in the environment than sub-6 GHz signals because the wavelength is in millimeters, so most objects in the environment appear relatively larger (for e.g., water drop). When in contact with such objects, mmWave signals might experience full or partial signal absorption, reflection, scattering, and/or diffraction. Shadowing effect is generally categorized into three categories: penetration losses, foliage losses, body, and hand losses. mmWave behaves differently in several aspects from the sub-6 GHz frequencies. Let’s discuss the key challenges that would be faced while working with mmWave due to its inherent characteristics. 1. Losses in mmWave: The propagation link loss in mmWave is significantly higher than in low bands/mid bands. Moreover, the loses in the non-line of sight (NLOS) scenario are further higher as compared to line of sight (LOS) scenario, for the same frequency band in mmWave. Below are the key losses considered while planning a network in mmWave
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