Performance evaluation of a layered space-time structure for MIMO systems
No Thumbnail Available
Date
2011-07
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Addis Ababa University
Abstract
MIMO systems are an appealing candidate for emerging fourth-generation wireless networks due
to their potential to exploit space diversity for increasing conveyed throughput without wasting
bandwidth and power resources. Particularly, layered space-time architecture (LST) proposed by
Foschini, is a technique to achieve a significant fraction of the theoretical capacity with a
reasonable implementation complexity. It is based on signal processing and conventional one
dimensional coding, which includes vertical BLAST (Bell Laboratories Layered Space Time)
and diagonal BLAST. BLAST accomplishes this by splitting a single user’s data stream into
multiple sub-streams and using an array of transmitter antennas to simultaneously launch the
parallel sub-streams. All sub-streams are transmitted in the same frequency band, so spectrum is
used very efficiently. Since the user’s data is being sent in parallel over multiple antennas, the
effective transmission rate is increased roughly in proportion to the number of antenna elements
used.
In this thesis, we focus on the performance evaluation of a layered space-time structure for
MIMO systems under Rayleigh fading condition. Firstly, we throughly understand the different
layered space-time architectures and investigate the performance of general V-BLAST
architecture with Maximum Likelihood (ML), Zero-Forcing (ZF), Minimum Mean-Square Error
(MMSE), the Successive Interference Cancellation (SIC) and the Ordered Successive
Interference Cancellation (OSIC) detectors for 2 × antenna arrangement. Here, in addition to
performance (BER), the different detection algorithms are evaluated in terms of computational
complexity. From the results, we have seen that the maximum-likelihood (ML) detector is
optimum in the sense of achieving the minimum error probability. Unfortunately, the complexity
of the ML detector is exponential in the constellation size and the dimensions of the system. But,
by using the SIC & OSIC detectors, we approach the performance of the ML detector with lower
computational complexity. It is also shown that the average performance is improved when the
number of receive antenna increases. Finallly we understand and evaluate performance bound
trends of Rate Compatible Punctured Convolutional (RCPC) codes and investigate the unequal
error protection capabilities of rate compatible punctured convolutional codes (RCPC codes)
when used together with V-BLAST MIMO systems for a mother code rate of 1/4. The
Description
Keywords
ML, MMSE, ZF, V-BLAST, MIMO, SIC, OSIC, RCPC codes