2. In this project we show the performance of MIMO-OFDM
system in Rayleigh Fading Channel
MIMO-OFDM system is very popular technique for mobile
communication now a day’s .We compares Ergodic and
Outage Capacity , with taking various numbers of
Transmitting and Receiving antennas and various
performance measures such as SNR, BER etc.
MIMO-OFDM, Ergodic Capacity, BER, SNR Outage Capacity
3. Ever-increasing demands in communication industry
towards wireless
Challenges:
- to improve spectral efficiency
- efficient bandwidth utilization
- economical Signal Processing
algorithms
- high speed processing h/w
4. - Multiple i/p multiple o/p
antenna array
- Used to increase data rates,
improve capacity and BER
(bit error rate) of the system
Diagram of a MIMO wireless transmission
system. - Typically used with OFDM so
as to suit best needs in next
generation comm. i.e. “4G”
5. SU-MIMO (Single User - MIMO)
this utilizes MIMO technology to improve the
performance towards a single user.
MU-MIMO (Multi User - MIMO)
this enables multiple users to be served through
the use of spatial multiplexing techniques.
6. Definition
The first OFDM schemes presented in 1966
Development of OFDM over years
7. - Converts a frequency selective
channel into a parallel collection
of frequency flat sub channels
- Orthogonal frequency division
multiplexing uses bandwidth
efficiently
- Improves multipath fading issues
- Reduces the effect of ISI (inter-
sub carrier interference)
OFDM System block Diagram
8. It distributes the data over a large number of carriers that
are spaced apart at precise frequencies.
This spacing provides the "orthogonality" in this
technique which prevents the demodulators from seeing
frequencies other than their own.
9. ◦ Two conditions must be considered for the
orthogonality between the subcarriers.
Each subcarrier has exactly an integer number of cycles in the
FFT interval.
The number of cycles between adjacent subcarriers differs by
exactly one.
10.
11.
12. STTD (space time transmit diversity)
SM (spatial multiplexing)
AMC (adaptive modulation & coding) with modulation techniques such as
QPSK, 16-QAM, 64-QAM
H-ARQ (Hybrid automatic repeat request)
Shared access and MAC (medium access control) used for scheduling
packet access with Qos
13. Coupling MIMO and OFDM concepts to improve data rates in
downlink of wireless communication networks.
Analyzing the performance and building a prototype of
Wireless WAN’S using MIMO-OFDM
Use of adaptive loading algorithms such as Chows and
Compello’s.
Employing SVD (singular value decomposition) method to
increase the performance incase of MIMO
14. Survey, Implementation and performance analysis of existing MIMO
Learning s/w and h/w
Developing efficient algorithms
Software synchronization development
Various candidate coding and receiver strategies
Identification of Equipment
Implementation of prototype
15. The results obtained from these tests indicate very good
performance for the MIMO-OFDM prototype.
Concept is proving to be very robust in highly dispersive
channels
Cost reduction is being investigated through various methods
Simulation results show that at any given BER the adaptive
SISO system will be outperformed by the adaptive MIMO
system
Other future work areas involve the improvement of MIMO
processing complexity and practical implementation issues.
