07-12-2012, 04:54 PM
Efficient Pilot Patterns and Channel Estimations for MIMO-OFDM Systems
[attachment=42990]
BACKGROUND
FUTURE terrestrial (or wireless) broadcasting systems are
expected to support high-quality and high data-rate multimedia
services such as three dimensional high definition digital
television (3D-HDTV) and ultra-HDTV. Recently, an advanced
broadcasting system applying several transmit antennas,
so-called multiple-input single-output (MISO) system [1], [2],
or several transmit and receive antennas, so-called multi-input
multi-output (MIMO) system [3]–[5], has gained increased interest
since their performance is considerably improved compare
with a single-input single-output (SISO) system [6]. In particular,
it is noticed that the MIMO orthogonal frequency division
multiplexing (MIMO-OFDM) system incorporating with a
space time/frequency coding (STC/SFC) can dramatically mitigate
the intersymbol interference (ISI) affected by frequency-selective
fading as well as a significant time/frequency diversity
gain [7]–[12].
The aim of this is to efficiently design various pilot patterns
and channel estimations for the MIMO-OFDM system.
Specially, referring a distributed SFC processing for use in
MISO-OFDM system of the second generation terrestrial digital
video broadcasting (DVB-T2) [1], [2], we consider two
independent SFCs for two sets of two transmit antennas as
shown in Fig. 1. The associated issues are summarized as
follows
1) Exploiting an orthogonal property found in the pilot
patterns of DVB-T2 system [13], we design the efficient
scattered pilot (SP), edge pilot (EP), and continuous
pilot (CP) patterns.
PERFORMANCE EVALUATIONS
Computer simulations were conducted to verify the realization
and effectiveness of the proposed pilot patterns, CFR,
and CIR estimations under the simulation conditions listed in
Table II. The choice of parameters such as the GI, bandwidth,
and pilot patterns are dictated by DVB-T2 system. In addition,
the modulations of 4-QAM and 16-QAM were adopted for
MIMO-OFDM and MISO-OFDM systems, respectively, to
evaluate the variation trends of MSE and SER performances
for the same throughput. For the CIR and CFR estimations, a
LI was adopted for TI, while the LI and low-pass filter (LF) set
having four bandwidths corresponding to GI-1/128, GI-1/32,
GI-1/16, GI-19/256 were adopted for FI [11]. Here, it is noticed
that the LF was implemented with a Kaiser window-
CONCLUSION
In this paper, we have presented the MIMO-OFDM system,
especially by considering independent and properly distributed
This article has been accepted for inclusion in a future issue of this journal. Content is final as presented, with the exception of pagination.
6 IEEE TRANSACTIONS ON BROADCASTING
two SFCs on the MISO-OFDM system of DVB-T2. In particular,
we have proposed the efficient pilot patterns, i.e., SP, EP,
and CP, from the orthogonal property of a unitary matrix. We
have also proposed the efficient CFR and CIR estimations exploiting
those pilot patterns. Finally, through the performance
evaluations,we have verified the efficiency of the proposed pilot
patterns and channel estimations.
[attachment=42990]
BACKGROUND
FUTURE terrestrial (or wireless) broadcasting systems are
expected to support high-quality and high data-rate multimedia
services such as three dimensional high definition digital
television (3D-HDTV) and ultra-HDTV. Recently, an advanced
broadcasting system applying several transmit antennas,
so-called multiple-input single-output (MISO) system [1], [2],
or several transmit and receive antennas, so-called multi-input
multi-output (MIMO) system [3]–[5], has gained increased interest
since their performance is considerably improved compare
with a single-input single-output (SISO) system [6]. In particular,
it is noticed that the MIMO orthogonal frequency division
multiplexing (MIMO-OFDM) system incorporating with a
space time/frequency coding (STC/SFC) can dramatically mitigate
the intersymbol interference (ISI) affected by frequency-selective
fading as well as a significant time/frequency diversity
gain [7]–[12].
The aim of this is to efficiently design various pilot patterns
and channel estimations for the MIMO-OFDM system.
Specially, referring a distributed SFC processing for use in
MISO-OFDM system of the second generation terrestrial digital
video broadcasting (DVB-T2) [1], [2], we consider two
independent SFCs for two sets of two transmit antennas as
shown in Fig. 1. The associated issues are summarized as
follows
1) Exploiting an orthogonal property found in the pilot
patterns of DVB-T2 system [13], we design the efficient
scattered pilot (SP), edge pilot (EP), and continuous
pilot (CP) patterns.
PERFORMANCE EVALUATIONS
Computer simulations were conducted to verify the realization
and effectiveness of the proposed pilot patterns, CFR,
and CIR estimations under the simulation conditions listed in
Table II. The choice of parameters such as the GI, bandwidth,
and pilot patterns are dictated by DVB-T2 system. In addition,
the modulations of 4-QAM and 16-QAM were adopted for
MIMO-OFDM and MISO-OFDM systems, respectively, to
evaluate the variation trends of MSE and SER performances
for the same throughput. For the CIR and CFR estimations, a
LI was adopted for TI, while the LI and low-pass filter (LF) set
having four bandwidths corresponding to GI-1/128, GI-1/32,
GI-1/16, GI-19/256 were adopted for FI [11]. Here, it is noticed
that the LF was implemented with a Kaiser window-
CONCLUSION
In this paper, we have presented the MIMO-OFDM system,
especially by considering independent and properly distributed
This article has been accepted for inclusion in a future issue of this journal. Content is final as presented, with the exception of pagination.
6 IEEE TRANSACTIONS ON BROADCASTING
two SFCs on the MISO-OFDM system of DVB-T2. In particular,
we have proposed the efficient pilot patterns, i.e., SP, EP,
and CP, from the orthogonal property of a unitary matrix. We
have also proposed the efficient CFR and CIR estimations exploiting
those pilot patterns. Finally, through the performance
evaluations,we have verified the efficiency of the proposed pilot
patterns and channel estimations.