Since long ago, multi-antenna technology has been used in mobile wireless systems. During the early base station transmission and in-vehicle mobile station reception period, multi-path propagation in large cell network topology will cause selective fading, thus affecting signal quality, especially in urban areas. The previous approach was to use base station transmit and on-board receiver antenna diversity to solve this problem. As mobile phones become smaller and smaller, in-vehicle communication devices have been simplified to adopt Bluetooth audio connectivity technology, and receive diversity in mobile devices has been phased out. However, this trend will soon change: the latest WLAN implementations use multi-antenna spatial streams that increase transmission bandwidth and speed. With the advent of low-cost hardware implementing this advanced technology, the first release of the 3GPP LTE (Third Generation Partnership Project Long Term Evolution) standard, especially its TDD (Time Division Duplex) version, has proposed and implemented various multi-antennas. technology. Again, the underlying wireless channel uses a single-channel transmit and a single receive antenna called SISO (single-input single-output). This simple wireless channel sets the benchmark for signal transmission performance, on the basis of which all more complex transmission configurations can be measured. SIMO (Single Input Multiple Output) provides greater receive antenna redundancy than the SISO reference, supporting the use of receive diversity techniques in the receiver, such as maximum ratio combining. This can improve the SINR observed at the device receiver and help improve performance under channel fading conditions. MISO (Multiple Input Single Output) provides transmit antenna redundancy and, as in the case of LTE, supports transmit diversity techniques such as AlamouTI symbol coding or Space Frequency Block Coding (SFBC). Like SIMO, this also improves the SINR observed at the device receiver and helps provide protection against channel fading. Neither SIMO nor MISO can increase data throughput, but they can reduce the bit error rate and thus the amount of data that needs to be retransmitted. MIMO (Multiple Input Multiple Output) provides additional transmit and receive antenna redundancy. If the same data is sent to the transmit antenna, this redundancy can be used to improve the SINR on the device receiver using the same transmit and receive diversity techniques described above, or to sacrifice some or all of the possible SINR performance improvements in order to achieve higher Spectral efficiency. Spatially multiplexed transmission technology (using a transmit antenna to transmit independent data streams) can provide higher data throughput (SU-MIMO or single-user MIMO) for a single user, or increase system cell capacity (MU-MIMO or multi-user) MIMO). In addition to these diversity and spatial multiplexing techniques, multiple antenna configurations can be used to concentrate transmission or reception in a particular direction. This technique is called beamforming and can be fixed beamforming or variable beamforming depending on the application and can improve system performance. Beamforming technology can be used in many different frequency applications, including sonar and seismology, acoustics, wireless communications, radio astronomy and radar. Lithium Battery Pack For Hybrid Electric Locomotive Lithium Battery For Electric Car,Cylindrical Battery,2000-2500Kw Lifepo4 Battery System,Ce Certificated Lithium Battery Henan Xintaihang Power Source Co.,Ltd , https://www.taihangbattery.com