MIMO, Multiple Input Multiple Output

 MIMO, Multiple Input Multiple Output:

MIMO, Multiple Input Multiple Output

 MIMO, Multiple Input Multiple Output

MIMO, Multiple input multiple output with two transmitters and two receivers with high speed independent data streams


MIMO systems provide multiple parallel data steams. The data steams an decoded by scattering produced by cluster. Channel estimation methods an used to separate the individual channels at the receiver end.

If the order of MIMO is increased, i.e. 4x4 MIMO then four antennas on thi system and mobile would be practically difficult. It would need strong scattering environment covering multiple paths and increasing the syste capacity or coverage. Orthogonal independent channels are created as result of scattering.

To improve the signal quality SFBC diversity processing is used in the L systems.

With two antennas at all the antenna sites, the typical MIMO is 2x2 MIM for an HSPA+ and LTE indoor system.

The data speed can be doubled if the scattering is perfect with no correlatis between the signal paths. 

Practically we cannot double the data speed because of interferences buildings.

MIMO systems provide better comparison compared to SISO systems. In open areas MIMO indoor performance can be increased by 30% as compared to SISO systems and in high scattering regions the MIMO systems indoor performance can be around 100%. Thus, we can obtain high throughput with MIMO.

WLAN (Wi-Fi) uses MIMO with 802.11n standard. Multiple small antennas are present in modern devices like laptops, data cards, mobiles, tablets.

The HSPA uses MIMO in commercial networks. But installing two antennas in mobile devices is difficult practically considering the mobile hardware limitations.

Must Read>> HSPA (High Speed Packet Access)

Spatial separation for antennas changes from 3 to 7 wavelengths. However, with modern developments the spatial separation use two-to three wavelengths or three-to-five wavelengths depending on the environment.

Some mobile devices are supporting dual antennas that operate for MIMO. Both the antennas are cross-polarized.

For optimizing systems to obtain maximum throughput we need to consider following parameters:

(1) Signal quality: On the MIMO paths, the signal to noise ratio (S/N) should be good for maintaining 64 QAM high modulation performance throughput the cell.

(2) Low noise factor on uplink: We need to have a system with good uplink performance, low noise factor for indoor LTE and HSPA systems. This keeps the mobile transmit power low.

(3) Ease of installation: The systems should be deployed to provide maximum throughput. We can obtain 85% performance with implementation in 95% of buildings and 95% performance with implementation in 10% buildings.

(4) Uniform coverage: To obtain maximum performance the system should provide uniform coverage.

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