Simulation of Multiple Transmitter Communication System Using IT++

Contributors Chalmers University: Ali Behrevan, Thomas Eriksson Chalmers University: Ali Behrevan, Thomas Eriksson Bilkent University: Mustafa Durukal, Hakan Arslan, Gul Safak Bilkent University: Mustafa Durukal, Hakan Arslan, Gul Safak POLITO: Daniel Bustos POLITO: Daniel Bustos

Base-band Model of a Single Transmitter – Receiver Communication System that uses OFDM

Two Sources of Distortion In The Received Signal Additive noise channel between the transmitter and receiver sides Additive noise channel between the transmitter and receiver sides Nonlinearity of the power amplifier at the end of the transmitter side Nonlinearity of the power amplifier at the end of the transmitter side

Effect of Noise on the System Performance

Figure of merit: Bit Error Rate (BER) Figure of merit: Bit Error Rate (BER) Error rate in a 16-QAM OFDM system with no amplification Error rate in a 16-QAM OFDM system with no amplification SNR (signal to noise ratio) limits the BER of the system SNR (signal to noise ratio) limits the BER of the system To reduce the effect –>use Convolutional Encoder To reduce the effect –>use Convolutional Encoder

Effect of Nonlinear Power Amplifier on the Transmitted Signal In-band Outer-band

Base-band Model of a Three Transmitter – Receiver System

Distortions Introduced by the Nonlinear Power Amplifier In a single transmitter – receiver system In a single transmitter – receiver system In-band distortion In-band distortion In a multiple transmitter – receiver system In a multiple transmitter – receiver system In-band distortion In-band distortion Outer-band distortion Outer-band distortion

Distortions Introduced by the Nonlinear Power Amplifier

Outer-band distortions overlap with and are added to the in-band distortions Outer-band distortions overlap with and are added to the in-band distortions Results in degradation in the BER performance Results in degradation in the BER performance The amount of degradation depends on The amount of degradation depends on Degree of the nonlinearity Degree of the nonlinearity Spacing between adjacent channels (Δf) Spacing between adjacent channels (Δf) Distortions Introduced by the Nonlinear Power Amplifier

Degree of Nonlinearity (in simulations) identified by the amplifier parameter IBO (input backoff) (in simulations) identified by the amplifier parameter IBO (input backoff) How far the input is from the saturation region IBO

The Simulation Program -Link Simulator- used for simulating three transmitter – receiver communication system used for simulating three transmitter – receiver communication system Each block is set by the user as an input Each block is set by the user as an input gives the BER (bit error rate) as an output gives the BER (bit error rate) as an output

Inputs of the Program Number of transmitted bits Number of transmitted bits Encoder type Encoder type Base-band modulator Base-band modulator Number of carriers in OFDM Number of carriers in OFDM Oversampling factor Oversampling factor Power amplifier type Power amplifier type IBO (input back-off) IBO (input back-off) SNR (signal to noise ratio) SNR (signal to noise ratio) Channel spacing Channel spacing

Character-based Interface for Link Simulator

Graphical Interface for Link Simulator

In All Simulations Total number of bits = 10 6 Total number of bits = 10 6 No coding No coding 16 – QAM OFDM 16 – QAM OFDM Number of carriers = 1024 Number of carriers = 1024 Oversampling factor = 16 Oversampling factor = 16

Power Amplifier Types Linear Linear Hard Limiter Hard Limiter Soft Limiter Soft Limiter Rapp Rapp 3 rd order polynomial 3 rd order polynomial Saleh Saleh

Power Amplifier Types SOFT LIMITER

Power Amplifier Types HARD LIMITER

Power Amplifier Types RAPP

Power Amplifier Types 3 rd Order Polynomial

Power Amplifier Types SALEH (AM/AM)

Power Amplifier Types SALEH (AM/PM)

Other Inputs For each amplifier type simulations are done for the following parameters: For each amplifier type simulations are done for the following parameters: IBO (in dB): integer from 0 to 6 IBO (in dB): integer from 0 to 6 SNR (in dB): integer from 0 to 20 SNR (in dB): integer from 0 to 20 Channel spacing ÷ 2W = 1 : 0.2 : 3 Channel spacing ÷ 2W = 1 : 0.2 : 3 W is the channel bandwidth of the transmitted signal W is the channel bandwidth of the transmitted signal

Graphical Interface for Link Simulator

Simulation Results

Graphical Interface for Link Simulator The August 1990 T.H.E. Journal reports advantages of GUI over character-based user interface (CUI) The August 1990 T.H.E. Journal reports advantages of GUI over character-based user interface (CUI) GUI users completed 58% more correct work in the same time frame than CUI users GUI users completed 58% more correct work in the same time frame than CUI users After 2 days learning to use microcomputers and applications, GUI users rated their frustration at 2.7 (out of 10), whereas CUI users rated their frustration at 5.3. After 2 days learning to use microcomputers and applications, GUI users rated their frustration at 2.7 (out of 10), whereas CUI users rated their frustration at 5.3. GUI users attempted 23% more new tasks than CUI users GUI users attempted 23% more new tasks than CUI users

Designing a GUI for Link Simulator requires integration of IT++ with MFC (Microsoft Foundation Classes) in Microsoft Visual Studio.NET requires integration of IT++ with MFC (Microsoft Foundation Classes) in Microsoft Visual Studio.NET offers users a better and easier way of doing simulations offers users a better and easier way of doing simulations