2,126 research outputs found
Improved Modeling of the Correlation Between Continuous-Valued Sources in LDPC-Based DSC
Accurate modeling of the correlation between the sources plays a crucial role
in the efficiency of distributed source coding (DSC) systems. This correlation
is commonly modeled in the binary domain by using a single binary symmetric
channel (BSC), both for binary and continuous-valued sources. We show that
"one" BSC cannot accurately capture the correlation between continuous-valued
sources; a more accurate model requires "multiple" BSCs, as many as the number
of bits used to represent each sample. We incorporate this new model into the
DSC system that uses low-density parity-check (LDPC) codes for compression. The
standard Slepian-Wolf LDPC decoder requires a slight modification so that the
parameters of all BSCs are integrated in the log-likelihood ratios (LLRs).
Further, using an interleaver the data belonging to different bit-planes are
shuffled to introduce randomness in the binary domain. The new system has the
same complexity and delay as the standard one. Simulation results prove the
effectiveness of the proposed model and system.Comment: 5 Pages, 4 figures; presented at the Asilomar Conference on Signals,
Systems, and Computers, Pacific Grove, CA, November 201
Energy and bursty packet loss tradeoff over fading channels: a system-level model
Energy efficiency and quality of service (QoS) guarantees are the key design goals for the 5G wireless communication systems. In this context, we discuss a multiuser scheduling scheme over fading channels for loss tolerant applications. The loss tolerance of the application is characterized in terms of different parameters that contribute to quality of experience (QoE) for the application. The mobile users are scheduled opportunistically such that a minimum QoS is guaranteed. We propose an opportunistic scheduling scheme and address the cross-layer design framework when channel state information (CSI) is not perfectly available at the transmitter and the receiver. We characterize the system energy as a function of different QoS and channel state estimation error parameters. The optimization problem is formulated using Markov chain framework and solved using stochastic optimization techniques. The results demonstrate that the parameters characterizing the packet loss are tightly coupled and relaxation of one parameter does not benefit the system much if the other constraints are tight. We evaluate the energy-performance tradeoff numerically and show the effect of channel uncertainty on the packet scheduler design
Embracing corruption burstiness: Fast error recovery for ZigBee under wi-Fi interference
This is the author accepted manuscript. The final version is available from the publisher via the DOI in this record.The ZigBee communication can be easily and severely interfered by Wi-Fi traffic. Error recovery, as an important means for
ZigBee to survive Wi-Fi interference, has been extensively studied in recent years. The existing works add upfront redundancy to
in-packet blocks for recovering a certain number of random corruptions. Therefore the bursty nature of ZigBee in-packet corruptions
under Wi-Fi interference is often considered harmful, since some blocks are full of errors which cannot be recovered and some blocks
have no errors but still requiring redundancy. As a result, they often use interleaving to reshape the bursty errors, before applying
complex FEC codes to recover the re-shaped random distributed errors. In this paper, we take a different view that burstiness may be
helpful. With burstiness, the in-packet corruptions are often consecutive and the requirement for error recovery is reduced as
ârecovering any k consecutive errorsâ instead of ârecovering any random k errorsâ. This lowered requirement allows us to design far
more efficient code than the existing FEC codes. Motivated by this implication, we exploit the corruption burstiness to design a simple
yet effective error recovery code using XOR operations (called ZiXOR). ZiXOR uses XOR code and the delay is significantly reduced.
More, ZiXOR uses RSSI-hinted approach to detect in packet corruptions without CRC, incurring almost no extra transmission
overhead. The testbed evaluation results show that ZiXOR outperforms the state-of-the-art works in terms of the throughput (by 47%)
and latency (by 22%)This work was supported by the National Natural Science
Foundation of China (No. 61602095 and No. 61472360), the
Fundamental Research Funds for the Central Universities (No.
ZYGX2016KYQD098 and No. 2016FZA5010), National Key
Technology R&D Program (Grant No. 2014BAK15B02), CCFIntel
Young Faculty Researcher Program, CCF-Tencent Open
Research Fund, China Ministry of EducationâChina Mobile
Joint Project under Grant No. MCM20150401 and the EU FP7
CLIMBER project under Grant Agreement No. PIRSES-GA-
2012-318939. Wei Dong is the corresponding author
Energy Optimal Transmission Scheduling in Wireless Sensor Networks
One of the main issues in the design of sensor networks is energy efficient
communication of time-critical data. Energy wastage can be caused by failed
packet transmission attempts at each node due to channel dynamics and
interference. Therefore transmission control techniques that are unaware of the
channel dynamics can lead to suboptimal channel use patterns. In this paper we
propose a transmission controller that utilizes different "grades" of channel
side information to schedule packet transmissions in an optimal way, while
meeting a deadline constraint for all packets waiting in the transmission
queue. The wireless channel is modeled as a finite-state Markov channel. We are
specifically interested in the case where the transmitter has low-grade channel
side information that can be obtained based solely on the ACK/NAK sequence for
the previous transmissions. Our scheduler is readily implementable and it is
based on the dynamic programming solution to the finite-horizon transmission
control problem. We also calculate the information theoretic capacity of the
finite state Markov channel with feedback containing different grades of
channel side information including that, obtained through the ACK/NAK sequence.
We illustrate that our scheduler achieves a given throughput at a power level
that is fairly close to the fundamental limit achievable over the channel.Comment: Accepted for publication in the IEEE Transactions on Wireless
Communication
Delay Performance of MISO Wireless Communications
Ultra-reliable, low latency communications (URLLC) are currently attracting
significant attention due to the emergence of mission-critical applications and
device-centric communication. URLLC will entail a fundamental paradigm shift
from throughput-oriented system design towards holistic designs for guaranteed
and reliable end-to-end latency. A deep understanding of the delay performance
of wireless networks is essential for efficient URLLC systems. In this paper,
we investigate the network layer performance of multiple-input, single-output
(MISO) systems under statistical delay constraints. We provide closed-form
expressions for MISO diversity-oriented service process and derive
probabilistic delay bounds using tools from stochastic network calculus. In
particular, we analyze transmit beamforming with perfect and imperfect channel
knowledge and compare it with orthogonal space-time codes and antenna
selection. The effect of transmit power, number of antennas, and finite
blocklength channel coding on the delay distribution is also investigated. Our
higher layer performance results reveal key insights of MISO channels and
provide useful guidelines for the design of ultra-reliable communication
systems that can guarantee the stringent URLLC latency requirements.Comment: This work has been submitted to the IEEE for possible publication.
Copyright may be transferred without notice, after which this version may no
longer be accessibl
Masking of errors in transmission of VAPC-coded speech
A subjective evaluation is provided of the bit error sensitivity of the message elements of a Vector Adaptive Predictive (VAPC) speech coder, along with an indication of the amenability of these elements to a popular error masking strategy (cross frame hold over). As expected, a wide range of bit error sensitivity was observed. The most sensitive message components were the short term spectral information and the most significant bits of the pitch and gain indices. The cross frame hold over strategy was found to be useful for pitch and gain information, but it was not beneficial for the spectral information unless severe corruption had occurred
Theoretical Analysis and Evaluation of NoCs with Weighted Round-Robin Arbitration
Fast and accurate performance analysis techniques are essential in early
design space exploration and pre-silicon evaluations, including software
eco-system development. In particular, on-chip communication continues to play
an increasingly important role as the many-core processors scale up. This paper
presents the first performance analysis technique that targets networks-on-chip
(NoCs) that employ weighted round-robin (WRR) arbitration. Besides fairness,
WRR arbitration provides flexibility in allocating bandwidth proportionally to
the importance of the traffic classes, unlike basic round-robin and
priority-based arbitration. The proposed approach first estimates the effective
service time of the packets in the queue due to WRR arbitration. Then, it uses
the effective service time to compute the average waiting time of the packets.
Next, we incorporate a decomposition technique to extend the analytical model
to handle NoC of any size. The proposed approach achieves less than 5% error
while executing real applications and 10% error under challenging synthetic
traffic with different burstiness levels.Comment: This paper is accepted in International Conference on Computer Aided
Design (ICCAD), 202
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