What are the challenges of Beam and Blockage in mmWave communication?5 answersBeam and blockage pose significant challenges in mmWave communication systems. The vulnerability of millimeter wave links to blockages, whether caused by malicious attackersor moving obstacles like humans, can lead to high outage probabilities and data loss. To address these challenges, proactive measures such as utilizing multiple reflections for robustnessand implementing predictive mechanisms for blockage detectionare crucial. Advanced technologies like massive MIMO and beamforming, coupled with deep learning models for blockage and beam prediction, offer solutions for seamless connectivity and proactive handovers in ultra-dense networks. These approaches aim to enhance user experience, maintain connectivity, and mitigate the impact of blockages in mmWave communication systems.
What are the major bottlenecks or challenges of using plasmon wave resonance for terahertz detection, especially when using graphene?5 answersUtilizing plasmon wave resonance for terahertz detection with graphene faces significant challenges. One major bottleneck is the mismatch between the atomically thin graphene and the long terahertz wavelengths, hindering efficient interaction. Additionally, the poor absorption of ultrathin graphene limits its response over a broad frequency range, impacting detection efficiency. To address these challenges, strategies like using metallic gratings to enhance excitation efficiency of graphene plasmons have been proposed, improving absorption and responsivity. Furthermore, the need for smart control over radiation, propagation, and detection of THz signals, along with the high gain requirements and large electrical size at THz frequencies, pose additional hurdles. These obstacles highlight the complexity and need for innovative solutions in leveraging plasmon wave resonance for efficient terahertz detection with graphene.
What are the challenges in microwave imaging?5 answersMicrowave imaging faces several challenges that are slowing down its adoption. The underlying problem at the core of microwave imaging is a non-linear and ill-posed inverse scattering problem. There are still several challenges to be addressed in microwave imaging, including the development of clinical systems for stroke diagnosis with robust and reliable results. Another challenge is the reconstruction of dielectric properties inside parts of the human body, which is crucial for medical applications such as early cancer diagnostics and focused microwave thermotherapy. Additionally, current imaging systems have challenges such as complex hardware design and ineffective backprojection-imaging algorithms, as well as large scanning time due to the electronically scanning one by one of the co-located receive-transmit antennas.
What are the key challenges in the assessment of TMP array antennas for CPS applications?5 answersThe key challenges in the assessment of TMP array antennas for CPS applications include the need for high-gain characteristics and agile beamforming with wide-scan capabilities. Additionally, extensive system trade studies are necessary to ensure the best investment strategy for transitioning from single antennas supporting single functions to multi-function, multi-frequency shared apertures. The implementation of phase array technology is fundamental to this strategy, and affordability is a crucial factor in its adoption. Furthermore, the analysis of finite array antennas can be computationally intensive, requiring efficient techniques for solving the problem in a shorter time period. Finally, the RF performance and construction materials of microstrip patch antenna arrays need to be optimized for specific applications, such as in the space industry.
What‘s the best scenario of terahertz communication ??5 answersThe best scenario for terahertz communication is in a satellite constellation, specifically in a low Earth orbit (LEO) configuration. THz communication in this scenario can handle the challenges of Doppler shift and tracking problems, and achieve ultra-high communication speeds over long distances. Additionally, THz communication in this scenario has been shown to increase capacity and reliability through the use of a new non-orthogonal multiple access (NOMA) scheme called direct NOMA. This makes it a promising technology for future communication systems, such as beyond 5G mobile networks.
What are the current limitations of THz communication?5 answersThe current limitations of THz communication include strong path loss attenuation, limited transmission power, vulnerability to blockage, and low penetration capability. These limitations affect the maximum number of carriers that can be activated and the signal coverage capability. To address these limitations, techniques such as Joint-Transmission Coordinated Multi-Point (JT-CoMP) and multi-connectivity have been proposed. However, the implementation of JT-CoMP in THz channels is challenging due to distance-frequency-dependent molecular absorption. Additionally, while increasing the number of multi-connectivity links can improve THz communication performance, there is a saturation point beyond which the performance gain is limited. To overcome the limitations, the use of intelligent reflecting surfaces (IRS) has been explored to regulate the phase shifts of THz waves and improve coverage capability.