Multiple Antenna Techniques in 4G wireless communication.

MIMO is a required multiple antenna technique in 4G LTE to attain high data rate requirements.  
With multiple antennas we can achieve significant improvements in following performance parameters.
1. Higher data rates over the air interface.
2. Farther signal penetration and improved coverage.
3. Lower signal losses due to reduced interference.
4. Lower power consumption.
5. Support of more users with better quality and spectral efficiency.
Multiple antenna’s are in order of two:2x, 4x or 8x.

Multiple antenna core functionality.
The core functionality of all multiple antenna techniques is to send the same signal over the air on multiple channels. Chances of signal getting corrupted on multiple channels is very limited and signal can be recovered easily at receiver. These techniques also focuses on sending the signal energy in one direction rather than broadcasting.

LTE - 4G Wireless Technology

Digital fundamentals.

Interview Questions.

Various industry standard Multiple Antenna techniques are MIMO, Adaptive antenna System(AAS) and Antenna diversity (AD)
Multiple Input and Multiple Output - MIMO
MIMO is a leading technique used in LTE and is discussed in details this section.
Downlink MIMO
LTE downlink by default requires MIMO 2x2 antenna configuration (In WiMax its optional). By MIMO 2x2 we mean 2 transmit antennas at the base station and 2 receive antennas at the mobile.
Uplink MIMO
MIMO schemes for LTE Uplink are different in comparison to Downlink. In order to reduce complexities in mobile UL path, a different antenna scheme is used. This scheme is called MU-MIMO, where MU stands for Multiple Users.
In MU-MIMO, multiple user terminals can transmit simultaneously on the same resource block. Only one transmit transmit antenna is required for mobile. This techniques is only possible with use of orthogonal SC-FDMA modulation.
Adaptive Antenna System - AAS
Other names - Beam-forming, Beam-steering or Beam-shaping.
Detailed discussion on AAS is covered in this section.

Antenna Diversity - AD
To improve reliability at receiver, multiple copies of a packet are transmitted over several antennas. If one of the packet gets corrupted at receiver, other packets are used to decode the useful data.
Different diversity coding's are listed below
Space diversity
Transmit/Receive diversity
Pattern diversity
Polarization diversity
Detailed discussion on Antenna diversity is covered in this section.


Verilog Tutorial.

LTE Tutorial.

Memory Tutorial.

Hope you liked! this page. Don't forgot to access relevant previous and next sections with links below.