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Basics on the Theory of Fading Channels and Diversity
Published in Athanasios G. Kanatas, Konstantina S. Nikita, Panagiotis Mathiopoulos, New Directions in Wireless Communications Systems, 2017
Vasileios M. Kapinas, Georgia D. Ntouni, George K. Karagiannidis
Spatial diversity, also known as antenna diversity,† is the most commonly used form to obtain several copies of the same information-bearing signal by deploying multiple antennas at the Rx or/and Tx side. The redundant signals are then skillfully combined in order to increase the total average SNR. The term site diversity is sometimes used as an alternative to spatial diversity. However, site diversity is a macrodiversity technique that fits better in the context of satellite communications systems operating in Ka band and above, where two or more ground stations are linked together to provide more robust downlink signal reception against rain fading.
Pattern and Polarization Diversity in Antennas
Published in Binod Kumar Kanaujia, Surendra Kumar Gupta, Jugul Kishor, Deepak Gangwar, Printed Antennas, 2020
Ashwani Kumar, Prashant Chaudhary
Diversity means a range of different things. In a harsh environment, a wireless communication system faces many problems. Several diversity schemes are available to improve the reliability and link quality of a wireless network for LTE/smartphones and the Internet of things (IoT). Diversity system means to increase the throughput without increasing the bandwidth. Typically, in antenna diversity, two or more antennas are used. In the outdoor environment, a signal takes multipath to reach the destination by bouncing off from different objects and suffers from fading, phase delay, attenuation, etc. Multipath fading and phase delay are the primary factors that affect communication in the indoor environment. To resolve these problems, several diversity schemes are used, among which three are very common. They are spatial diversity, pattern diversity, and polarization diversity. In spatial diversity, antennas occupy different locations in space; in polarization diversity, antennas are differ in polarization; and in pattern diversity, main beams are directed over a large angular area. Antenna diversity systems provide a better link quality and higher data rates as compared to a single antenna. In the real environment, most of the communication is through non-line of sight, in the diversity system, if one antenna is in deep fade area. In contrast, another antenna receives a strong signal to improve the channel capacity fading has to reduce. Antenna diversity also improves the impedance matching. The polarization diversity scheme reduces the polarization mismatch loss and enhances the mismatching and signal-to-noise ratio (SNR) up to 12 dB [1], which will improve the overall communication efficiency. So, these various diversities schemes can be used for the enhancement of the overall quality of the communication.
Next Generation Wireless Technologies
Published in K. R. Rao, Zoran S. Bojkovic, Bojan M. Bakmaz, Wireless Multimedia Communication Systems, 2017
K. R. Rao, Zoran S. Bojkovic, Bojan M. Bakmaz
Antenna diversity is a transmission technique in which similar data (replicas) signals are transmitted from multiple antennas to improve the signal-to-noise ratio (SNR). Such a gain is equal to NtNr and can be achieved by using multiple receiver antennas (diversity reception) or by using multiple transmitting antennas (transmit diversity). A diversity-combining circuit combines or selects the signals from the receiver antennas to provide an improved signal quality.
Mutual coupling reduction in a textile ultra-wide band MIMO antenna
Published in The Journal of The Textile Institute, 2023
Nuri Yilmazer, Mariam El Gharbi, Raul Fernandez-Garcia, Ignacio Gil
Current wireless communication systems require a very high data rate and reliability. After Federal Communication Council’s (FCC) decision regarding the usage of (3.1–10.6 GHz) frequency band for commercial applications created a platform for high data transmission for contemporary wireless communication systems (Yang & Giannakis, 2004). In a single antenna wireless communication system, the performance of the communication will be severely degraded due to the multipath fading effect especially in indoor environments. In order to overcome this bottleneck and to meet the increased demand for the high data rates in wireless communication systems, MIMO antenna systems emerged as new technology for enhancing both spectral efficiency and link robustness (Li et al., 2013). MIMO antenna utilizes multiple antennas at both transmitter and receiver. Multiple antenna diversity technique will lead to improvement in signal strength, Signal-to-Noise Ratio (SNR) and better data rate improvements as well as better outage probability rates (Li et al., 2013). In order to significantly improve the channel capacity and the reliability, the number of antennas in a MIMO system needs to be increased. The capacity of the MIMO depends on the number of antennas, spacing between antenna elements and the configuration/orientation of the antennas in the system (Chen et al., 2018).