Channel Modeling – Page 3

October 7, 2011November 21, 2013Channel Modeling, LTE, WiMAX

LTE Multipath Channel Models

When a wireless signal travels from a transmitter to a receiver it follows multiple paths. The signal may travel directly following the line of sight between the transmitter and receiver, it may bounce off the ground and reach the receiver or it may be reflected by multiple buildings on the way to the receiver. When these copies of the same signal arrive at the receiver they are delayed and attenuated based upon the path length that they have followed and various other factors. A well known technique to model such a wireless channel is to model it as an FIR […]

September 23, 2011February 14, 2014Channel Modeling, WiMAX

WiMAX Path Loss Calculation

Calculation of the path loss is fundamental to Wireless System Design. There are many models available for calculating the path loss such as Okumura Model, Hata Model, COST-231 Model and more recently the SUI (Stanford University Interim) Model. The SUI Model has been specifically proposed for Broadband Wireless Access Systems such as WiMAX. It defines three types of environments namely A, B and C which are equivalent to the urban, suburban and rural environments defined in the earlier models. According to this model the path loss can be calculated as: PL=A+10*n*log10(d/do)+Xf+Xh+s where n=a-(b*hb)+(c/hb) A=20*log10(4*pi*do/lambda) Xf=6.0*log10(f/2000) Xh=-10.8*log10(hr/2) for A&B Xh=-20.0*log10(hr/2) for […]

May 29, 2011August 23, 2011Channel Modeling

Simulating a SISO Ring Model

We simulate the SISO Ring Model described previously by varying the transmit receive separation from 50m to 500m. Keeping the ring radius fixed at 20m the angular spread of the channel decreases as the receiver moves away from the transmitter. It is observed that the power level of the received signal fluctuates as the distance ‘d’ is varied. However, after a certain critical distance (around 250 m) the power vs distance curve approaches a straight line.

May 28, 2011March 22, 2013Channel Modeling

Simulating a SISO 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. Ring Model Given below is the MATLAB code for a SISO Ring […]

May 27, 2011November 15, 2011Channel Modeling

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 […]