Mimo technology for wireless broadband mobile communication systems

MIMO technology can be used as a bridge to connect old and new wireless technologies, so that the two can develop and integrate harmoniously. So it is already an important technology in the next generation of wireless broadband mobile communication systems. The following will give you an in-depth analysis of its development.

MIMO technology has become one of the key technologies in the wireless communication field. However, it is a huge challenge in the industry to reduce the algorithm complexity and implementation complexity of MIMO technology on the basis of ensuring certain system performance.

To increase system capacity, the next-generation wireless broadband mobile communication system will adopt MIMO technology, that is, multiple antennas will be placed on the base station side, and multiple antennas will be placed on the mobile platform, a mimo communication link is formed between the base station and the Mobile Station. The wireless broadband mobile communication system using MIMO technology can be divided into two categories from the multi-antenna placement method at the base station end: one is that the antennas of multiple base stations are arranged in a centralized manner to form an antenna array and placed in the coverage area, this type can be called centralized MI-MO; the other type is that multiple antennas of base stations are scattered in the coverage area, which can be called distributed MIMO.

MIMO technology can be simply and directly applied to traditional cellular mobile communication systems, replacing a single antenna of a base station with an antenna array composed of multiple antennas. The base station uses an antenna array to communicate with a mobile station with multiple antennas in the cell. From the perspective of system structure, there is no fundamental difference between such MIMO systems and traditional single-in-single-output (SISO) cellular communication systems.

The traditional distributed antenna system can overcome the channel path loss caused by large-scale fading and Shadow Fading. It can form a good system coverage in the residential area and solve the dead corner of communication in the residential area, improve communication service quality. Recent studies on MIMO technology have found that the combination of traditional distributed antenna systems and MIMO technology can increase the system capacity. This new distributed MIMO system structure-distributed wireless communication system (DWCS) [8] has become an important research hotspot in MIMO technology.

In a distributed mimo dwcs system, multiple antennas scattered in the cell are connected to the base station processor through optical fibers. A mobile station with multiple antennas communicates with a base station antenna scattered nearby, and establishes a MIMO communication link with the base station. This system structure not only has the advantages of the traditional distributed antenna system, reduces the path loss, overcomes the shadow effect, but also significantly improves the channel capacity through MIMO technology. Compared with centralized MIMO, the distance between base station antennas of DWCS is far away. The channel fading between different antennas and mobile stations can be considered completely unrelated and the channel capacity is larger. In general, the distributed MIMO system has a larger channel capacity, lower system power consumption, better system coverage, and better scalability and flexibility.

Distributed mimo dwcs systems also bring about some new problems. MIMO links established between the mobile station and adjacent antennas in the residential area are different from those of the mobile station because the positions of different antennas of the base station are different, the delay of signals from multiple antennas at the base station to the mobile station is also different, which leads to new research problems. At present, more studies are conducted on capacity analysis. In addition, the research contents include: Specific synchronization technology, channel estimation, Antenna Selection, transmission scheme, and signal detection technology. These problems need to be studied in depth.

MIMO technology has become one of the key technologies in the wireless communication field. With the continuous development in recent years, MIMO technology will be increasingly applied to various wireless communication systems. In terms of wireless broadband mobile communication systems, the 3rd-Generation Mobile Communication Cooperation Plan (3GPP) has already included MIMO technology-related content in the standard. The B3G and 4G systems will also apply MIMO technology. In the wireless broadband access system, standards such as 802.16e, 802.11n, and 802.20 are also developed using MIMO technology. In other studies on wireless communication systems, such as ultra-wideband (UWB) systems and perception radio systems (CR), MIMO technology is being considered.

With the increase in the number of antennas, the complexity of MIMO technology is greatly increased, thus limiting the number of antennas used and making full use of the advantages of MIMO technology. At present, how to reduce the complexity and implementation complexity of MIMO technology on the basis of ensuring certain system performance has become a huge challenge in the industry.