04-03-2011, 03:19 PM
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BLAST
INTRODUCTION
BLAST was developed by Foschini at Lucent Technologies' Bell Laboratories.
A wireless communications technique which uses multi antennas at both transmitter and receiver to permit transmission rates far in excess of those possible using conventional approaches.
Using the BLAST approach, it is possible to exploit multipath.
NEED
Growing Need for Wireless Capacity
Bandwidth is Limited
Only Solution is Higher Spectral Efficiency
System Requirement
The performance of the BLAST architectures depends on three key factors.
The system operates in a rich Rayleigh scattering environment.
Appropriate coding structures are used.
Powerful encoding (FEC codes) and perfect decoding.
Members Of BLAST Family
D-BLAST
V-BLAST
Turbo-BLAST
D-BLAST
The original scheme D-BLAST is a wireless set up that use a multi antenna array a both the transmitter and receiver, as well as diagonally layered coding sequence.
The coding sequence is to be dispersed across diagonals in space-time. In an independent Rayleigh scattering environment, this processing structure leads to theoretical rates that grow linearly with the number of antennas these rates approaching 90% of Shannon capacity.
V-BLAST
Foschini et al proposed V-BLAST (Vertical-Bell Lab Layered Space-Time) code with a detection algorithm based on
Interference Suppression
Interference Cancellation
Advantages :
simplicity and lower complexity
Disadvantages :
lower capacity than Shannon bound
Comparison with Existing Techniques
Unlike a Frequency Division Multiple Access (FDMA) approach, each transmitted signals occupies the signal bandwidth.
Unlike Time Division Multiple Access (TDMA), the entire system bandwidth is used simultaneously by all of the transmitters all of the time.
BLAST
INTRODUCTION
BLAST was developed by Foschini at Lucent Technologies' Bell Laboratories.
A wireless communications technique which uses multi antennas at both transmitter and receiver to permit transmission rates far in excess of those possible using conventional approaches.
Using the BLAST approach, it is possible to exploit multipath.
NEED
Growing Need for Wireless Capacity
Bandwidth is Limited
Only Solution is Higher Spectral Efficiency
System Requirement
The performance of the BLAST architectures depends on three key factors.
The system operates in a rich Rayleigh scattering environment.
Appropriate coding structures are used.
Powerful encoding (FEC codes) and perfect decoding.
Members Of BLAST Family
D-BLAST
V-BLAST
Turbo-BLAST
D-BLAST
The original scheme D-BLAST is a wireless set up that use a multi antenna array a both the transmitter and receiver, as well as diagonally layered coding sequence.
The coding sequence is to be dispersed across diagonals in space-time. In an independent Rayleigh scattering environment, this processing structure leads to theoretical rates that grow linearly with the number of antennas these rates approaching 90% of Shannon capacity.
V-BLAST
Foschini et al proposed V-BLAST (Vertical-Bell Lab Layered Space-Time) code with a detection algorithm based on
Interference Suppression
Interference Cancellation
Advantages :
simplicity and lower complexity
Disadvantages :
lower capacity than Shannon bound
Comparison with Existing Techniques
Unlike a Frequency Division Multiple Access (FDMA) approach, each transmitted signals occupies the signal bandwidth.
Unlike Time Division Multiple Access (TDMA), the entire system bandwidth is used simultaneously by all of the transmitters all of the time.
