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ABSTRACT: Lattice coding techniques may be used to derive achievable rate regions which
outperform known independent, identically distributed (i.i.d.) random codes in
multi-source relay networks and in particular the two-way relay channel. Gains
stem from the ability to decode the sum of codewords (or messages) using
lattice codes at higher rates than possible with i.i.d. random codes. Here we
develop a novel lattice coding scheme for the Two-way Two-relay Channel: 1 <->
2 <-> 3 <-> 4, where Node 1 and 4 simultaneously communicate with each other
through two relay nodes 2 and 3. Each node only communicates with its
neighboring nodes. The key technical contribution is the lattice-based
achievability strategy, where each relay is able to remove the noise while
decoding the sum of several signals in a Block Markov strategy and then
re-encode the signal into another lattice codeword using the so-called
"Re-distribution Transform". This allows nodes further down the line to again
decode sums of lattice codewords. This transform is central to improving the
achievable rates, and ensures that the messages traveling in each of the two
directions fully utilize the relay's power, even under asymmetric channel
conditions. All decoders are lattice decoders and only a single nested lattice
codebook pair is needed. The symmetric rate achieved by the proposed lattice
coding scheme is within 0.5 log 3 bit/Hz/s of the symmetric rate capacity.
12/2012;
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ABSTRACT: Uncompressed high-definition video streaming over wireless personal area networks is a challenging problem because of the high data rate requirement and channel variations. With the advances in RF technology and the huge bandwidth available worldwide in the 57-66 GHz millimeter-wave unlicensed spectrum, mmWave WPANs that can support multigigabit transmission are being developed. However, compared to low-frequency signals (2.4 or 5 GHz), mmWave signals are more fragile; indeed, the propagation losses are significantly higher. In this article we present an mmWave system for supporting uncompressed HD video up to 3 Gb/s. The system includes various efficient error protection and concealment schemes that exploit unequal error resilience properties of uncompressed video. Some of them have been adopted in the emerging 60 GHz WPAN standards such as WirelessHD, ECMA TC48, and IEEE 802.15.3c. Simulations using real uncompressed HD images indicate that the proposed mmWave system can maintain, under poor channel conditions, good average peak-signal-to-noise-ratio and low video quality metric scores.
IEEE Communications Magazine 01/2009; · 3.79 Impact Factor
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ABSTRACT: Uncompressed HD (high-definition) video delivery over wireless personal area networks (WPANs) is a challenging problem because of the limited bandwidth and variations in channel. The 60 GHz millimeter-wave (mmWave) band has recently drawn much interest because of the huge bandwidth that it can provide from 57-66 GHz unlicensed spectrum available worldwide. However, to date a system design supporting uncompressed HD video over WPAN is still lacking. In this paper, we develop, simulate, and evaluate an mmWave system for supporting uncompressed video streaming over wireless (UVoW). New features of the UVoW system incorporates: (i) UEP (unequal error protection) where different video bits (MSBs and LSBs) are protected differently, (ii) a multi-CRC to determine whether MSB or/and LSB portions are in error, (iii) UV-ARQ, uncompressed video retransmission protocol which allows the receiver to request only those portions of a video packet which have high importance. Simulations indicate that the UVoW system achieves significantly higher video quality than normal systems under various wireless channel conditions. This shows that UVoW is a promising wireless system supporting uncompressed HD video.
Consumer Communications and Networking Conference, 2008. CCNC 2008. 5th IEEE; 02/2008
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ABSTRACT: Millimeter wave (mmWave) technology provides possibility to replace uncompressed high-definition video cables (such as HDMI, DVI, or DisplayPort) with wireless links. However, it is very challenging to meet the strict quality of service (QoS) requirements from uncompressed video streaming applications since 60 GHz wireless signals can be easily blocked by human body and other obstacles. In this paper, we first discuss the specific technical challenges in mmWave system to support long-time stable video streaming. Then, we propose a new adaptive multi-beam transmission solution in which pixel partitioning, switched multi- beam transmission, and fast video format adaptation are key techniques to solve the raised technical problems. Initial performance evaluation shows that our approach can achieve high- quality video streaming performance.
Future Generation Communication and Networking (FGCN 2007); 01/2008
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WCNC 2008, IEEE Wireless Communications & Networking Conference, March 31 2008 - April 3 2008, Las Vegas, Nevada, USA, Conference Proceedings; 01/2008
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WCNC 2008, IEEE Wireless Communications & Networking Conference, March 31 2008 - April 3 2008, Las Vegas, Nevada, USA, Conference Proceedings; 01/2008
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Future Generation Communication and Networking, FGCN 2007, Ramada Plaza Jeju, Jeju-Island, Korea, December 6-8, 2007, Proceedings; 01/2007
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ABSTRACT: Battery powered handheld devices need to operate for extended periods of time, and thus require to be energy conserving. This paper evaluates the performance of a new power saving scheme, called PSMP (power save multiple poll), developed for the upcoming IEEE 802.11n WLANs. Using both analysis and simulations, we investigate the benefits of using PSMP in a wireless LAN having multiple voice-over-IP (VoIP) clients. To boost the reliability of a PSMP sequence, we propose a new recovery scheme, which we call PSMP recovery. Our results show that the PSMP recovery scheme significantly improves the efficiency of the original PSMP sequence.
Vehicular Technology Conference, 2006. VTC-2006 Fall. 2006 IEEE 64th; 10/2006
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Consumer Communications and Networking Conference, 2006. CCNC 2006. 3rd IEEE; 02/2006
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ABSTRACT: Uncompressed HD (high-definition) video delivery over wireless personal area networks (WPANs) is a challenging problem because of the limited bandwidth and variations in channel. The 60GHz millimeter-wave (mmWave) band has recently drawn much interest because of the huge bandwidth that it can provide from 57-66 GHz unlicensed spectrum available worldwide. However, to date a system design supporting uncompressed HD video over WPAN is still lacking. In this paper, we develop, simulate, and evaluate an mmWave system for supporting Uncompressed Video streaming over Wireless (UVoW). New features of the UVoW system incorporates: (i) UEP (unequal error protection) where different video bits (MSBs and LSBs) are protected differently, (ii) a multi-CRC to determine whether MSB or/and LSB portions are in error, (iii) UV-ARQ, uncompressed video retransmission protocol which allows the receiver to request only those portions of a video packet which have high importance. Simulations indicate that the UVoW system achieves significantly higher video quality than normal systems under various wireless channel conditions. This shows that UVoW is a promising wireless system supporting uncompressed HD video.
Conference Proceedings.
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ABSTRACT: In 60 GHz wireless networks, autonomous coordinator selection is required to find a device to coordinate the transmissions among devices. In order to minimize the power consumption for the coordinator, we utilize the direction information extracted from beamformed transmissions in finding the coordinator automatically. The problem is formulated as a K-center problem, which is a NP-hard problem in general. Analysis is carried out to find optimal solutions in certain tractable topologies. Numerical algorithms and simulation results are further presented for random two dimensional topologies.
Conference Proceedings.
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ABSTRACT: Uncompressed HD (high-definition) video delivery over wireless personal area networks (WPANs) is a challenging problem because of the limited bandwidth and variations in channel. The most straight forward technique to recover from channel errors is to retransmit corrupted packets. However, retransmissions introduce significant delay/jitter and require additional bandwidth. Therefore, retransmissions may be unsuitable for uncompressed video streaming. In this paper, we develop, simulate, and evaluate an millimeter- wave (mmWave) system for supporting uncompressed video streams up to 3-Gbps without any retransmissions. New features of the mmWave system incorporates: (i) UEP (unequal error protection) where different video bits (MSBs and LSBs) are protected differently, (ii) a multiple-CRC to determine whether MSB or/and LSB portions are in error, (iii) RS code swapping (RSS), an error concealment scheme which can conceal some errors in video pixels. Simulations using real uncompressed HD images indicate that the proposed mmWave system can maintain good average PSNR (peak-signal-to-noise-ratio) under poor channel conditions, achieving what is generally accepted as a good picture quality with PSNR values greater than 40 dB. Moreover, the proposed system results in less fluctuating PSNR values.
Conference Proceedings.
