BER performance simulation in a multi user MIMO TAS/MRC Nakagami-m channel using BPSK, QPSK and QAM

Under the Supervision of:

Mrs. Jayatri Bora,

(Asst. Professor, Department of ECE)

Vikas Pandey DE/12/EC/001

Rubina Khongsit DE/12/EC/002

Ruptanu Pal DE/12/EC/008

Tanya Singh DE/12/EC/020

Renji Thomas DE/11/EC/051

Kh. Nongpoknganba DE/11/EC/108

OBJECTIVE

Bit Error Rate Performance Simulation

For Multi user MIMO TAS/MRC Nakagami-m

Channel

Using BPSK, QPSK and QAM

Using Matlab

INSPIRATION

It is the most recent technique being used in

industries

Not much work has been done on Nakagami-

m fading

BPSK, QPSK and QAM are popularly used in

commercial MIMO devices

STEPS INVOLVED

• Channel Matrix with Nakagami-m distribution

• Separation of channel matrix for each user

Step 1: Channel Generation

• Compare the SNR for Tx

• Select the Tx• Select the best user

Step 2: Simulate the TAS/MRC •

Step 3: BER Performance Calculation

KEY TERMS

Mu-MIMO

TAS (Transmit Antenna Selection)

MRC (Maximal Ratio Combining)

Fading

Nakagami-m channel

BER

MIMO

MIMO: Multiple Input Multiple Output

Multiple antennas at both the transmitter and

receiver .

Offers increase in data throughput and link

range.

Spreads the same total transmit power over

the antennas to achieve:

an array gain

a diversity gain

SINGLE USER MIMO

Multiple antennas are physically connected to each individual terminal.

Fig 1: Single user MIMO

[1] Digital Communication by John G .Proakis 3rd edition Mc graw hill p 841

MULTI USER MIMO

Terminals transmit (or receive) signal to (or from) multiple users in the same band simultaneously.

Fig 2: Multi-user MIMO

[2] Digital Communication by John G .Proakis 3rd edition Mc graw hill p 842

TAS and MRC

TAS: Transmit Antenna Selection

Selects the best transmitting antenna.

Feedback path.

Reduces complexity.

MRC: Maximal-Ratio Combining

An optimal diversity technique with a maximum

SNR criterion.

TAS / MRC

An integrated TAS scheme with MRC at the receiver- TAS/MRC.

Retains the advantages of both.

Employs MRC at receiver.

Utilizes partial Channel State Information (CSI), the optimal SNR at the receiver.

Single antenna selected out of all possible transmit antennas

Maximizes the SNR at the receiver.

Fig 3: Multi-user MIMO System Model using TAS/MRC

[3] Mohammad Torabi, David Haccoun and Wessam Ajib, “Capacity and outage probability analysis of Multiuser Diversity in MIMO MRC Systems with Transmit Antenna Selection “.

SCHEDULING TECHNIQUE

Absolute SNR – based scheduling

An absolute SNR based scheduler at the base

station selects the best user among all the active

users.

Normalized SNR based proportional fair

scheduling

Scheduling scheme the base station selects the

user with the largest normalized SNR value.

FADING IN MIMO

Deviation of the attenuation affecting a

signal over certain propagation media[4].

The signal suffers loss in power due to

Shadowing

Reflection

Refraction

Scattering

Are represented by different mathematical

expressions

[4 ] Lars Ahlin & Jens Zander, Principles of Wireless Communications, pp.126.

NAKAGAMI-m FADING

The Nakagami-m distribution: Probability

distribution related to the gamma

distribution.

Two parameters:

a shape parameter, m (>1)

controlling spread parameter, Ω (=1)

Availability of a free parameter allows

flexibility.

NAKAGAMI-m FADING

Fig4: Probability Distribution Function of Nakagami distribution

[5] Nakagami M., “The m-distribution, a General Formula of Intensity Distribution of Rapid Fading in Statistical Methods in Radio Wave Propagation”, W. G. Hoffman, Ed., Pergamon, Oxford, England, 1960

NAKAGAMI-m FADING

m-parameter allows to cover both severe

and weak fading.

High value of m causes a negative impact on

the capacity of Mu-MIMO systems.

Used to model

land-mobile

indoor mobile multipath propagation

scintillating ionosphere radio links

[6] Proakis. J. and Salehi. M. “Digital Communication”, 5th Ed, Mc-Graw Hill, International Edition, 2008, p 52, 53.

MODULATION TECHNIQUES

Binary Phase Shift Keying (BPSK)

Quadrature Phase Shift Keying (QPSK)

Quadrature Amplitude Modulation (QAM)

BIT ERROR RATE (BER)

Key parameter used in assessing systems

transmitting digital data.

Defined as the rate at which error occurs in a

transmission system.

Can be translated into a simple formula

=

BIT ERROR RATE (BER)

Errors in the data, compromise the integrity

of the system.

BER assesses the performance of the

system.

BER enables the actual performance of a

system in operation to be tested.

SIMULATION AND RESULT

Fig. 5. BER for BPSK, QPSK and QAM in a mu-MIMO with 200 users, having Nakagami-m fading (m=2).

SIMULATION AND RESULT

Fig. 6. BER for BPSK, QPSK and QAM in a mu-MIMO with 500 users, having Nakagami-m fading (m=2).

INFERENCES

The energy per bit to noise power spectral

density ratio (EbNo) for

BPSK is from 0 to 4,

for QPSK is 0 to 8

for QAM is 0 to 16

No of users increases the error do decrease

The effect is more in BPSK and the least in QAM

Findings can be applied in designing of future

MIMO mobile devices

FUTURE ASPIRATIONS

Hardware appraisal of the simulated results

Comparison of practical & simulated results.