# Simulating a MIMO Ring Model

A Ring Model is a well known spatial channel model. It models the propagation channel as an unobstructed transmitter and a receiver surrounded by a ring of reflectors. The distance between the transmitter and receiver is usually much larger than the radius of the ring. The reflectors are distributed uniformly around the ring. This model is useful for modeling a scenario where a base station is located at sufficient altitude and is unobstructed whereas the mobile station is at ground level and is surrounded by a bunch of reflectors.

Given below is the MATLAB code that calculates the composite signal (from nth Tx element to mth Rx element) at the receiver for a MIMO channel composed of eight reflectors.

```%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
function [Et]=ring_mod2(d,r,psi,l,B,alpha,a)
Et=0;
for phi=0:pi/4:(2*pi)-(pi/4);
R_=sqrt((d-l*cos(psi)-r*cos(phi))^2+(r*sin(phi)-l*sin(psi))^2);
r_=sqrt((r*cos(phi)-a*cos(alpha))^2+(r*sin(phi)-a*sin(alpha))^2);
E=exp(-i*B(r_+R_))/(r_+R_);
Et=Et+E;
end
return
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%```

#### Author: Yasir Ahmed (aka John)

More than 20 years of experience in various organizations in Pakistan, the USA, and Europe. Worked as a Research Assistant within the Mobile and Portable Radio Group (MPRG) of Virginia Tech and was one of the first researchers to propose Space Time Block Codes for eight transmit antennas. The collaboration with MPRG continued even after graduating with an MSEE degree and has resulted in 12 research publications and a book on Wireless Communications. Worked for Qualcomm USA as an Engineer with the key role of performance and conformance testing of UMTS modems. Qualcomm is the inventor of CDMA technology and owns patents critical to the 4G and 5G standards.

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## 1 thought on “Simulating a MIMO Ring Model”

1. Safa Ahmed says:

This is totally cool.