Transcript 投影片 1 - National Tsing Hua University

Research Topics
on
Wireless Communications
1. Cognitive Radio Systems
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National Security Committee of Europe, Japan and USA have required mobile should
have the location function in future. It can be used for user location, mobile tracking,
security and military targeting.
In the urban area with complex environment there exist severe interferences in mobile
location and tracking such as shadowing and channel fading; We integrate following
techniques to solve the difficult design problems such as robust location and tracking of
mobile, and location detection, power allocation and lifetime of wireless sensor network:
Research topics:
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fuzzy estimation
Markov jumping
extended Kalman filter
data fusion
convex optimization
multi-objective optimization
Complex channel in urban area
2. Cooperative Wireless Communications
and Communication Security
 Motivation: Cooperative MIMO wireless
communications is a state-of-the-art technology,
but vulnerable to information security (secrecy) in
the presence of eavesdroppers or malicious users
(relays).
Receivers
 Cutting-edge physical-layer secure
communication researches:
 Design distributed relay beamforming and
cooperative jamming scheme to degrade the
reception performance of the eavesdroppers.
Eavesdropper
Cooperative relays
 Devise robust cooperative schemes (e.g., robust
relay beamforming) insensitive to disturbance
caused by malicious users (relays).
 Devise advanced cooperative schemes to identify
malicious users and can adapt the transmission
strategies according to the attacking strategies of
the malicious users.
Receivers
Cooperative relays
Malicious relay
3. Broadband Wireless Communications
 To meet the demand for multimedia streaming services, a broadband
wireless communication system must increase the transmission rate
and enhance the bandwidth efficiency.
 OFDM technology is a promising solution for future broadband
wireless communications.
 LTE/LTE-A is expected to become the main stream of broadband
wireless communications in the future.
3. Broadband Wireless Communications:
Research Topics
 High efficiency modulation technologies:
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Bandwidth-efficient modulation schemes:
 Can increase the available data rate and reduce the transmission
latency
Energy-efficient modulation schemes:
 Can reduce the energy consumption and improve the receiving
performance
 Multimedia broadcast/multicast service
(MBMS):
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MBMS is an efficient approach to provide multimedia services in
wireless communication systems
To support multiple multimedia streams in OFDM-based MBMS,
efficient radio resource allocation is one of the key issues
3. Broadband Wireless Communications:
Research Topics
 High mobility supporting techniques:
 In future broadband wireless communications,
supporting high data services for high-mobility
users is attractive and essential
 To meet this demand, the following techniques
are essential
 User mobility estimation technique
 Inter-carrier interference (ICI) cancellation
technique
4. Coding Theory and System Optimization
(A) Structured Low Density Parity Check (LDPC) Codes
and Associated Encoding/Decoding Algorithms:
 The lack of structure in random constructed LDPC code presents
serious disadvantages in terms of the large complexity of encoding and
decoding.
 For LDPC block codes, we will develop new algebraic constructions
of quasi-cyclic (QC) LDPC codes with enlarged minimum distance for
good error performance.
 New unequal error protection (UEP) schemes based on QC-LDPC
codes will also be investigated for practical applications.
 For LDPC convolutional codes, we will study new algebraic
constructions with guaranteed girth and corresponding efficient
encoding/decoding algorithms.
4. Coding Theory and System Optimization
(B) Error Control for Network-Coded Transmission:
 There are two types of network coding problems, coherent and
noncoherent, depending on the assumption whether the network
topology is known.
 Both approaches are susceptible to transmission errors caused by
noise, interference, or malicious jamming.
 For coherent network coding, we will conduct a well-round
investigation of performance evaluation of error control for noisy
channel networks, starting from a simple network topology and then to
a general network setting.
 For non-coherent network coding, the rank-metric approach for error
control will be studied. We will develop new types of rank-metric
codes and corresponding decoding algorithms. We will also conduct
probabilistic performance evaluation of the rank-metric approach for
error control, which has not been done in the literature.
4. Coding Theory and System Optimization
(C) Advanced Non-coherent Coded Transmission
Schemes for MIMO Communication Systems:
 For high mobility, the fading is rapid and the coherence interval is short.
Consequently, non-coherent techniques, which avoid the use of pilots for
channel estimation, can be adopted in MIMO systems designed for fast-fading
channels.
 In order to increase the transmission reliability, powerful outer channel codes,
such as turbo codes or low-density parity-check (LDPC) codes, can be serially
concatenated with the inner MIMO mapper suitable for non-coherent detection.
 This research topic focuses on designing several advanced non-coherent coded
communication systems, especially for channels with short coherence intervals.
Time varying channel under high mobility
5. Communication IC
 This research investigates the low-power
cognitive radio SOC system:
Cognitive radio SOC
 Low-power multi-standard FEC codec
 Power cognitive communication ICs
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5. Communication IC
(A) Cognitive Radio SoC:
 Focus on SoC for cognitive radio, which can
provide much more spectrum efficiency under
the techniques of spectrum sensing/detection and
efficient spectrum management.
 Focus on more robust spectrum sensing/detection
algorithms, low complexity/high power
efficiency DSP, efficient spectrum management,
and interference cancellation techniques.
 Combined with the developed SoC demo
platform, we can provide high performance
algorithms, SoCs and platform.
5. Communication IC
(B) Multi-standard FEC encoders and
decoders for future wireless device:
 All the wireless transmission standards such as cellular,
broadcast, and connectivity standards employ FEC
(forward error correction) coding scheme in order to
achieve high transmission reliability over noisy channel.
 In the future, multi-standard FEC codecs (encoders and
decoders) will become key components for a variety of
products such as mobile phones, portable entertainment
and notebooks.
 We will use algorithmic and architectural approaches to
design multi-standard FEC codec that achieves throughput
values of Gb/s with lower complexities and power
consumption levels within tight budgets imposed by the
battery capacity.
5. Communication IC
(C) Power Cognitive Communication ICs:
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Analog front-end circuits: In the unlicensed band, the RF
circuits can determine whether some mixing circuits are
operated or not according to the spectrum occupation
status so as to reduce power consumption.
Baseband signal processing circuits: The spectrum
occupation status or the channel quality determine the
algorithm for baseband signal processing. Then, we can
design the baseband digital signal processing circuits
using reconfigurable architecture so as to reduce power
consumption.
Important Achievements (Ⅰ)
 Low complexity space-time-trellis-coded MIMO decoder
algorithm and MISO decoder implementation
 The first STTC coded MISO decoder in the world
Important Achievements (II)
 Ultra low power FFT processor design and implementation
 The most power efficient FFT processor
Important Achievements (III)
 Super HDTV transmission SoC platform
H.264
 Won the NSoC project award
PSNR=24.29
Proposed System
PSNR=30.56
Important Achievements (IV)
 SoC Implementation and Demonstration of Multi-user
MIMO WiMAX Baseband Transceiver:
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Baseband MIMO transceiver conforming to IEEE802.16e-2005
Suitable for SISO/MIMO and variable subcarrier allocation
Best performance when published
200k gate count complexity reduction (~45% chip area reduction)
Low power consumption (2.3Mbps/mW) with high throughput (60Mbps)
 Achievements:
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2009 DAC/ISSCC student design contest winner
First prize at Phenix IC design contest
Technology transfer to industry
Important Achievements (V)
 Design and Implementation of Closed-Loop MIMO Communications:
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Combine GMD and antenna selection to boost performance, 1.5 dB gain over ML and 6 dB
gain over V-BLAST
Reduce over 50% complexity compared to the conventional antenna selection scheme
Reduce greatly the feedback information (from 80 bit to 7 bit under 4x4 MIMO)
Provide high reliable low complexity QR detector
Provide 120 Mbps throughput under maximum frequency 50 MHz with FPGA
implementation
 Achievements:
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2010 ASP-DAC university design contest winner
Important Achievements (VI)
 Wireless Front-end Chip Prototype
A Low-Power CMOS Linear-in-dB
Variable Gain Amplifier with
Programmable Bandwidth and
Stable Group Delay
A 0.5-V GFSK Demodulator with a
Standard 0.18um CMOS
A 1.2-V CMOS Limiter/RSSI/
Demodulator for Low-IF FSK
Receiver
A 11-bits 6-ps Resolution Time-to-Digital
Converter for All-Digital Frequency
Synthesizer
A Quantization Error Minimization
Method using DDS-DAC for
Wideband Fractional-N Frequency
Synthesizer
A Integrated Front-End with Noise
Reduction and Harmonic Mixing
Suppression for Mobile Video Handset
A Ultra-Low-IF Receiver FrontEnd for GFSK Wireless Interface
A Low-Cost Wireless Interface with
Minimum Setup Cost to Support CmRange Contactless SoC Testing