Book Section records
https://feeds.library.caltech.edu/people/Cui-Tao/book_section.rss
A Caltech Library Repository Feedhttp://www.rssboard.org/rss-specificationpython-feedgenenTue, 16 Apr 2024 13:30:00 +0000Polynomial Moment Relaxation for MIMO Detection
https://resolver.caltech.edu/CaltechAUTHORS:20110506-104232997
Authors: {'items': [{'id': 'Cui-Tao', 'name': {'family': 'Cui', 'given': 'Tao'}}, {'id': 'Ho-Tracey', 'name': {'family': 'Ho', 'given': 'Tracey'}}, {'id': 'Tellambura-Chinthananda', 'name': {'family': 'Tellambura', 'given': 'Chinthananda'}}]}
Year: 2006
DOI: 10.1109/ICC.2006.255286
We develop a polynomial-time detector for maximum
likelihood (ML) detection over multiple-input multiple-output (MIMO) channels. Our proposed polynomial moment relaxation (PMR) detection gives a unified framework for MIMO detection with relaxation including semi-definite relaxation as a special case. We give three approaches to replace a finite alphabet constraint with a polynomial constraint. Since both the objective function and the constraints are polynomials, we use a moment relaxation approach by applying the dual theories of moments and positive polynomials solvable by semi-definite programming.
With different relaxation orders, our PMR achieve a flexible
trade-off between complexity and performance.https://authors.library.caltech.edu/records/arsrc-pas27Multiple-Symbol Differential Detection for Single-Antenna and Multiple-Antenna Systems over Ricean-fading Channels
https://resolver.caltech.edu/CaltechAUTHORS:20110506-103423676
Authors: {'items': [{'id': 'Cui-Tao', 'name': {'family': 'Cui', 'given': 'Tao'}}, {'id': 'Tellambura-Chinthananda', 'name': {'family': 'Tellambura', 'given': 'Chintha'}}]}
Year: 2006
DOI: 10.1109/ICC.2006.254951
This paper considers multiple symbol differential detection (DD) for both single-antenna and multiple-antenna systems over flat Ricean-fading channels. We derive the optimal multiple symbol detection (MSD) decision rules for both Mary differential phase-shift keying (MDPSK) and differential unitary space-time modulation (DUSTM). The sphere decoder (SD) is adopted to solve the MSD for MDPSK. As well, an improved SD is proposed by using the Schnorr-Euchner strategy. A suboptimal MSD based decision feedback DD algorithm is proposed for the MSD of DUSTM. We also develop a sphere decoding bound intersection detector (SD-BID) to optimally solve the MSD problem for DUSTM, which still maintains low complexity. Simulation results show that our proposed MSD algorithms for both single-antenna and multiple-antenna systems reduce the error floor of conventional DD but with reasonably low computational complexity.https://authors.library.caltech.edu/records/a25x1-6p879Heuristic Tree Search for Detection and Decoding of Uncoded and Linear Block Coded Communication Systems
https://resolver.caltech.edu/CaltechAUTHORS:20110506-105351004
Authors: {'items': [{'id': 'Cui-Tao', 'name': {'family': 'Cui', 'given': 'Tao'}}, {'id': 'Ho-Tracey', 'name': {'family': 'Ho', 'given': 'Tracey'}}, {'id': 'Tellambura-Chinthananda', 'name': {'family': 'Tellambura', 'given': 'Chinthananda'}}]}
Year: 2006
DOI: 10.1109/ICC.2006.254759
A heuristic tree search algorithm is developed for
the maximum likelihood detection and decoding problem in
a general communication system. We propose several "cheap"
heuristic functions using constrained linear detectors and the minimum mean square errors (MMSE) detector. Even though
the MMSE heuristic function does not guarantee the optimal
solution, it has a negligible performance loss and provides a good complexity-performance tradeoff. For linear block coded systems, heuristic tree search is modified for soft decision decoding. High rate codes are decoded via the minimum state trellis, and low rate codes via the minimum complexity tree. Preprocessing is also discussed to further speed up the algorithms.https://authors.library.caltech.edu/records/qtzjs-my165Efficient blind decoding of orthogonal space-time block codes over time-selective fading channels
https://resolver.caltech.edu/CaltechAUTHORS:20110310-143335876
Authors: {'items': [{'id': 'Cui-Tao', 'name': {'family': 'Cui', 'given': 'Tao'}}, {'id': 'Tellambura-Chinthananda', 'name': {'family': 'Tellambura', 'given': 'Chintha'}}]}
Year: 2006
DOI: 10.1109/WCNC.2006.1696534
In this paper, we consider efficient blind decoder design
for orthogonal space-time block codes (OSTBCs). A general
decision rule for blind OSTBC decoding is derived assuming a
quasi-static flat multiple-input multiple-output (MIMO) Rayleigh
fading channel. We use the linear dispersion representation of
OSTBCs to derive a blind decoder that results in a quadratic
minimization problem, which can be solved efficiently by semidefinite
relaxation, sphere decoding or successive interference
cancellation. To resolve phase ambiguity problems inherent in
blind detectors, rather than using pilot symbols that results
in a bandwidth loss, we propose novel totally blind decoders
using dual constellations or a superimposed training scheme. To
alleviate the computational burden, a minimum mean-squareerror
(MMSE) channel estimator is also proposed to track the
time-varying channel without using the blind decoder.https://authors.library.caltech.edu/records/5e9t8-cgy78Linear Programming Detection and Decoding for MIMO Systems
https://resolver.caltech.edu/CaltechAUTHORS:20170515-163823021
Authors: {'items': [{'id': 'Cui-Tao', 'name': {'family': 'Cui', 'given': 'Tao'}}, {'id': 'Ho-Tracey', 'name': {'family': 'Ho', 'given': 'Tracey'}}, {'id': 'Tellambura-Chinthananda', 'name': {'family': 'Tellambura', 'given': 'Chintha'}}]}
Year: 2006
DOI: 10.1109/ISIT.2006.261741
We develop an efficient linear programming detector (LPD) for multiple-input multiple-output (MIMO) systems. Instead of using the usual l2 norm, our proposed LPD uses the l1 norm as the detection metric, resulting in a mixed-integer linear program (MILP). Two branch-and-bound algorithms are proposed to solve the MILP. The solution of the MILP achieves the same full diversity order as the maximum likelihood detector. The MILP is further relaxed to a linear program (LP), which can be readily solved using the standard simplex method. We show that in some cases the solution of the LP is guaranteed to be that of the MILP. The LPD is also extended to the joint detection and decoding of linear block coded MIMO systems. Our LPD can be immediately implemented using mature circuits design for the simplex algorithm.https://authors.library.caltech.edu/records/9dw5m-96851Efficient signal detection for space-time block coding over time-selective fading channels
https://resolver.caltech.edu/CaltechAUTHORS:20110310-142643346
Authors: {'items': [{'id': 'Cui-Tao', 'name': {'family': 'Cui', 'given': 'Tao'}}, {'id': 'Tellambura-Chinthananda', 'name': {'family': 'Tellambura', 'given': 'Chintha'}}]}
Year: 2006
DOI: 10.1109/WCNC.2006.1696556
In this paper, we consider the signal detection for
space-time block coding over time-selective fading channels.
We derive a general maximum likelihood (ML) decision rule
for space-time block coding (STBC). The resulting detector is
valid for any number of receive antennas and for all STBC
systems that have the linear dispersion property. The detector
results in a quadratic minimization problem, which can be solved
efficiently by sphere decoding or nulling-and-cancelling detection.
For orthogonal STBC systems, we also propose a suboptimal
detector using the principle of parallel interference cancellation
(PIC) that is valid for systems with an arbitrary number of
receive antennas.https://authors.library.caltech.edu/records/0fa6c-vsj48Optimization based rate control for multicast with network coding: A multipath formulation
https://resolver.caltech.edu/CaltechAUTHORS:20100827-082408080
Authors: {'items': [{'id': 'Cui-Tao', 'name': {'family': 'Cui', 'given': 'Tao'}}, {'id': 'Chen-Lijun', 'name': {'family': 'Chen', 'given': 'Lijun'}}, {'id': 'Ho-Tracey', 'name': {'family': 'Ho', 'given': 'Tracey'}}]}
Year: 2007
DOI: 10.1109/CDC.2007.4434960
Network coding offers new capabilities for efficient
information multicasting in communication networks. In this
paper, we study rate control for multicast with network coding.
We propose a path-based multicasting scheme, where each
source has multiple paths to each receiver in the multicast
group. One advantage of this approach over a tree-based
approach is that it is easier to find a minimum cost set of paths
as compared to trees. We present three end-to-end rate control
algorithms which operate over the set of paths supplied by the
network layer. With random network coding, all algorithms can
be implemented in a distributed manner. Our algorithms can
also be generalized to solve other optimization problems with
non-strictly concave objection function.https://authors.library.caltech.edu/records/rsxxp-khw87Optimal Training Design for Channel Estimation in Amplify and Forward Relay Networks
https://resolver.caltech.edu/CaltechAUTHORS:20100827-092530965
Authors: {'items': [{'id': 'Cui-Tao', 'name': {'family': 'Cui', 'given': 'Tao'}}, {'id': 'Gao-Feifei', 'name': {'family': 'Gao', 'given': 'Feifei'}}, {'id': 'Nallanathan-A', 'name': {'family': 'Nallanathan', 'given': 'Arumugam'}}]}
Year: 2007
DOI: 10.1109/GLOCOM.2007.763
In this paper, we study training based channel
estimation for relay networks using the amplify-and-forward
(AF) transmission scheme. We first point out that separately
estimating the channel from source to relay and the channel from
relay to destination incurs several problems. We then propose a
new estimation scheme that directly estimates the overall channel
from source to destination. The proposed channel estimation well
matches the AF based space time coding that was developed
recently. Both linear least-square estimator and minimum mean-square-error estimator are studied. The corresponding optimal
training sequences and the optimal precoding matrices are also
derived.https://authors.library.caltech.edu/records/5mkwc-4rm88Opportunistic Source Coding for Data Gathering in Wireless Sensor Networks
https://resolver.caltech.edu/CaltechAUTHORS:20100827-112133009
Authors: {'items': [{'id': 'Cui-Tao', 'name': {'family': 'Cui', 'given': 'Tao'}}, {'id': 'Chen-Lijun', 'name': {'family': 'Chen', 'given': 'Lijun'}}, {'id': 'Ho-Tracey', 'name': {'family': 'Ho', 'given': 'Tracey'}}, {'id': 'Low-S-H', 'name': {'family': 'Low', 'given': 'Steven H.'}, 'orcid': '0000-0001-6476-3048'}, {'id': 'Andrew-L-L-H', 'name': {'family': 'Andrew', 'given': 'Lachlan L. H.'}}]}
Year: 2007
DOI: 10.1109/MOBHOC.2007.4428675
We propose a jointly opportunistic source coding and opportunistic routing (OSCOR) protocol for correlated data gathering in wireless sensor networks. OSCOR improves data gathering efficiency by exploiting opportunistic data compression and cooperative diversity associated with wireless broadcast advantage. The design of OSCOR involves several challenging issues across different network protocol layers. At the MAC layer, sensor nodes need to coordinate wireless transmission and packet forwarding to exploit multiuser diversity in packet reception. At the network layer, in order to achieve high diversity and compression gains, routing must be based on a metric that is dependent on not only link-quality but also compression opportunities. At the application layer, sensor nodes need a distributed source coding algorithm that has low coordination overhead and does not require the source distributions to be known. OSCOR provides practical solutions to these challenges incorporating a slightly modified 802.11 MAC, a distributed source coding scheme based on network coding and Lempel-Ziv coding, and a node compression ratio dependent metric combined with a modified Dijkstra's algorithm for path selection. We evaluate the performance of OSCOR through simulations, and show that OSCOR can potentially reduce power consumption by over 30% compared with an existing greedy scheme, routing driven compression, in a 4 x 4 grid network.https://authors.library.caltech.edu/records/v67bc-w4e96Maximum Likelihood Detection and Optimal Code Design for Differential Unitary Space-Time Modulation with Carrier Frequency Offset
https://resolver.caltech.edu/CaltechAUTHORS:20100827-105901767
Authors: {'items': [{'id': 'Cui-Tao', 'name': {'family': 'Cui', 'given': 'Tao'}}, {'id': 'Gao-Feifei', 'name': {'family': 'Gao', 'given': 'Feifei'}}, {'id': 'Nallanathan-A', 'name': {'family': 'Nallanathan', 'given': 'Arumugam'}}, {'id': 'Tellambura-Chinthananda', 'name': {'family': 'Tellambura', 'given': 'Chintha'}}]}
Year: 2007
DOI: 10.1109/GLOCOM.2007.532
In this paper, we answer the question that "Can conventional
differential unitary space time modulation (DUSTM)
be applied when there is an unknown carrier frequency offset
(CFO)?" and present a maximum likelihood (ML) detection rule
for this scenario. We analyze the asymptotical performance of our
ML detection and provide the code design criterion by using the
modified diversity product. The analysis also brings the insight
that our proposed decision rule is a new differential modulation
scheme in both temporal and spatial domains. Various simulations
are conducted, and the proposed algorithm is shown to
be more robust to the CFO drifting than the existing double
temporal differential modulation.https://authors.library.caltech.edu/records/8ryhj-er565ML CFO and PO Estimation in DCT OFDM Systems under Non-Circular Transmissions
https://resolver.caltech.edu/CaltechAUTHORS:20100827-145242260
Authors: {'items': [{'id': 'Cui-Tao', 'name': {'family': 'Cui', 'given': 'Tao'}}, {'id': 'Gao-Feifei', 'name': {'family': 'Gao', 'given': 'Feifei'}}, {'id': 'Nallanathan-A', 'name': {'family': 'Nallanathan', 'given': 'A.'}}, {'id': 'Tellambura-Chinthananda', 'name': {'family': 'Tellambura', 'given': 'Chintha'}}]}
Year: 2007
DOI: 10.1109/ICC.2007.1039
Frequency synchronization is one of the most important
components in orthogonal frequency-division multiplexing
(OFDM) systems. Recently, the discrete cosine transform (DCT)
based OFDM system has received wide attentions due to several
advantages. Hence, the study of frequency synchronization issue
for this newly raised system is well on its time. To provide
a thorough study, we consider the non-circular transmissions,
and the results can be easily generated to circular transmissions
if the elliptic variance is set to zero. We present three joint
maximum likelihood (ML) carrier frequency offset (CFO) and
phase offset (PO) estimators. From both the theoretical analysis
and the numerical comparisons, we found new advantages of
the DCT-OFDM over the traditional discrete Fourier transform
(DFT) based OFDM. These advantages, as well as those already
studied in the early works on DCT-OFDM, support the belief that
the DCT-OFDM is a new promising multi-carrier modulation
(MCM) scheme.https://authors.library.caltech.edu/records/8q8sp-v7f85Frequency Offset Tracking for OFDM Systems via Scattered Pilots and Virtual Carriers
https://resolver.caltech.edu/CaltechAUTHORS:20100827-141528018
Authors: {'items': [{'id': 'Cui-Tao', 'name': {'family': 'Cui', 'given': 'Tao'}}, {'id': 'Gao-Feifei', 'name': {'family': 'Gao', 'given': 'Feifei'}}, {'id': 'Nallanathan-A', 'name': {'family': 'Nallanathan', 'given': 'A.'}}]}
Year: 2007
DOI: 10.1109/ICC.2007.846
In this paper, we propose a new carrier frequency
offset (CFO) tracking algorithm for orthogonal frequency division
multiplexing (OFDM) systems. Assuming that the channel
remains constant during two consecutive OFDM blocks, a CFO
estimation algorithm is proposed based on the limited number
of pilots in each OFDM block. Identifiability of this pilot based
algorithm is fully discussed under the noise free environment. A
weighted algorithm is then developed by considering both pilot
carriers and virtual carriers. The asymptotic mean square error
(MSE) of the proposed algorithm is provided, and simulation results
clearly show the performance improvement of the proposed
algorithm over the existing methods.https://authors.library.caltech.edu/records/yc27e-p9867Distributed optimization in wireless networks using broadcast advantage
https://resolver.caltech.edu/CaltechAUTHORS:20100827-084745453
Authors: {'items': [{'id': 'Cui-Tao', 'name': {'family': 'Cui', 'given': 'Tao'}}, {'id': 'Chen-Lijun', 'name': {'family': 'Chen', 'given': 'Lijun'}}, {'id': 'Ho-Tracey', 'name': {'family': 'Ho', 'given': 'Tracey'}}]}
Year: 2007
DOI: 10.1109/CDC.2007.4434958
In this paper, we consider cross layer optimization
in wireless networks with wireless broadcast advantage,
focusing on the problem of distributed scheduling of broadcast
links. The wireless broadcast advantage is most useful
in multicast scenarios. For a multicast scenario, we give a
subgradient algorithm for distributed joint congestion control,
network coding and session scheduling, which however requires
centralized link scheduling. Under the primary interference
model, link scheduling problem is equivalent to a maximum
weighted hypergraph matching problem that is NP-complete.
To solve the scheduling problem distributedly, locally greedy
and randomized approximation algorithms are proposed and
shown to have bounded worst-case performance. With random
network coding, we obtain a fully distributed cross-layer design.
Numerical results show promising throughput gain using the
proposed algorithms, and surprisingly, in some cases even
with less complexity than cross-layer design without broadcast
advantage.https://authors.library.caltech.edu/records/b421s-jrv85Distributed minimum cost multicasting with lossless source coding and network coding
https://resolver.caltech.edu/CaltechAUTHORS:20100826-151540718
Authors: {'items': [{'id': 'Cui-Tao', 'name': {'family': 'Cui', 'given': 'Tao'}}, {'id': 'Ho-Tracey', 'name': {'family': 'Ho', 'given': 'Tracey'}}, {'id': 'Chen-Lijun', 'name': {'family': 'Chen', 'given': 'Lijun'}}]}
Year: 2007
DOI: 10.1109/CDC.2007.4434962
In this paper, we consider minimum cost lossless
source coding for multiple multicast sessions. Each session
comprises a set of correlated sources whose information is
demanded by a set of sink nodes. We propose a distributed end-to-end algorithm which operates over given multicast trees, and
a back-pressure algorithm which optimizes routing and coding
over the whole network. Unlike other existing algorithms, the
source rates need not be centrally coordinated; the sinks control
transmission rates across the sources. With random network
coding, the proposed approach yields completely distributed
and optimal algorithms for intra-session network coding. We
prove the convergence of our proposed algorithms. Some
practical considerations are also discussed. Experimental results
are provided to complement our theoretical analysis.https://authors.library.caltech.edu/records/qt1vn-1qr84On Distributed Distortion Optimization for Correlated Sources
https://resolver.caltech.edu/CaltechAUTHORS:20170425-162520744
Authors: {'items': [{'id': 'Cui-Tao', 'name': {'family': 'Cui', 'given': 'Tao'}}, {'id': 'Ho-Tracey', 'name': {'family': 'Ho', 'given': 'Tracey'}}, {'id': 'Chen-Lijun', 'name': {'family': 'Chen', 'given': 'Lijun'}}]}
Year: 2007
DOI: 10.1109/ISIT.2007.4557631
We consider lossy data compression in capacity-constrained networks with correlated sources. We develop, using dual decomposition, a distributed algorithm that maximizes an aggregate utility measure defined in terms of the distortion levels of the sources. No coordination among sources is required; each source adjusts its distortion level according to distortion prices fed back by the sinks. The algorithm is developed for the case of squared error distortion and high resolution coding where the rate distortion region is known, and is easily extended to consider achievable regions that can be expressed in a related form. Our distributed optimization framework applies to unicast and multicast with and without network coding. Numerical example shows relatively fast convergence, allowing the algorithm to be used in time-varying networks.https://authors.library.caltech.edu/records/hfexd-pz755Minimum Cost Integral Network Coding
https://resolver.caltech.edu/CaltechAUTHORS:20170425-161810594
Authors: {'items': [{'id': 'Cui-Tao', 'name': {'family': 'Cui', 'given': 'Tao'}}, {'id': 'Ho-Tracey', 'name': {'family': 'Ho', 'given': 'Tracey'}}]}
Year: 2007
DOI: 10.1109/ISIT.2007.4557632
In this paper, we consider finding a minimum cost multicast subgraph with network coding, where the rate to inject packets on each link is constrained to be integral. In the usual minimum cost network coding formulation, the optimal solution cannot always be integral. Fractional rates can be well approximated by choosing the time unit large enough, but this increases the encoding and decoding complexity as well as delay at the terminals. We formulate this problem as an integer program, which is NP-hard. A greedy algorithm and an algorithm based on linear programming rounding are proposed, which have approximation ratios k and 2k respectively, where k is the number of sinks. Moreover, both algorithms can be decentralized. We show by simulation that our algorithms' average performance substantially exceeds their bounds on random graphs.https://authors.library.caltech.edu/records/2fnpk-17s78Statistical Pruning for Near Maximum Likelihood Detection of MIMO Systems
https://resolver.caltech.edu/CaltechAUTHORS:20100909-133322426
Authors: {'items': [{'id': 'Cui-Tao', 'name': {'family': 'Cui', 'given': 'Tao'}}, {'id': 'Ho-Tracey', 'name': {'family': 'Ho', 'given': 'Tracey'}}, {'id': 'Tellambura-Chinthananda', 'name': {'family': 'Tellambura', 'given': 'Chintha'}}]}
Year: 2007
DOI: 10.1109/ICC.2007.905
We show a statistical pruning approach for maximum
likelihood (ML) detection of multiple-input multiple-output
(MIMO) systems. We present a general pruning strategy for
sphere decoder (SD), which can also be applied to any tree search
algorithms. Our pruning rules are effective especially for the case
when SD has high complexity. Three specific pruning rules are
given and discussed. From analyzing the union bound on the
symbol error probability, we show that the diversity order of the
deterministic pruning is only one by fixing the pruning probability.
By choosing different pruning probability distribution
functions, the statistical pruning can achieve arbitrary diversity
orders and SNR gains. Our statistical pruning strategy thus
achieves a flexible trade-off between complexity and performance.https://authors.library.caltech.edu/records/5bypp-dg578Opportunistic source coding for data gathering in wireless sensor networks
https://resolver.caltech.edu/CaltechAUTHORS:20161005-155121935
Authors: {'items': [{'id': 'Cui-Tao', 'name': {'family': 'Cui', 'given': 'Tao'}}]}
Year: 2007
DOI: 10.1145/1347787.1347801
We propose a jointly opportunistic source coding and oppor
tunistic routing (OSCOR) protocol for correlated
data gathering in wireless sensor networks. OSCOR
improves data gathering efficiency by exploiting
opportunistic data compression and multi-user diversity on wireless broadcast. OSCOR attacks challenges
across network protocol layers by incorporating a slightly modified 802.11 MAC, a distributed source coding
scheme based on Lempel-Ziv code
and network coding, and a node compression ratio dependent metric combined with a modified Dijkstra's algorithm for
path selection. We simulate OSCOR's performance and
show it reduces the number of transmissions by nearly
25% compared with other schemes in small networks.https://authors.library.caltech.edu/records/0zj2w-r1158Space-Time Communication Protocols for N-way Relay Networks
https://resolver.caltech.edu/CaltechAUTHORS:20110407-113333118
Authors: {'items': [{'id': 'Cui-Tao', 'name': {'family': 'Cui', 'given': 'Tao'}}, {'id': 'Ho-Tracey', 'name': {'family': 'Ho', 'given': 'Tracey'}}, {'id': 'Kliewer-J', 'name': {'family': 'Kliewer', 'given': 'Jörg'}}]}
Year: 2008
DOI: 10.1109/GLOCOM.2008.ECP.205
We address communication protocols for N-way relay networks with M antennas at the relay and a single antenna at the N source terminals. In particular, amplify-and-forward
(AF), decode-and-forward (DF), and compress-and-forward (CF)
strategies are extended to these networks, and in addition, two new relaying protocols, denoise-and-forward and estimate-andforward, are proposed. In the first part of the paper, the performance of these schemes is analyzed in terms of the achievable rate region. Also, the optimal diversity-multiplexing tradeoff is derived for both AF and DF. The second part of the paper is devoted to practical space-time transmission strategies. Linear dispersion codes are used, which are optimized by maximizing the sum rate. For AF a diversity order of close to M can be achieved by using a specific space-time code construction.https://authors.library.caltech.edu/records/xe8yx-5dz47Physical Layer Differential Network Coding for Two-way Relay Channels
https://resolver.caltech.edu/CaltechAUTHORS:20110407-113423361
Authors: {'items': [{'id': 'Cui-Tao', 'name': {'family': 'Cui', 'given': 'Tao'}}, {'id': 'Gao-Feifei', 'name': {'family': 'Gao', 'given': 'Feifei'}}, {'id': 'Tellambura-Chinthananda', 'name': {'family': 'Tellambura', 'given': 'Chintha'}}]}
Year: 2008
DOI: 10.1109/GLOCOM.2008.ECP.884
In this work, we consider differential modulation in
two-way relay channels (TWRC). In single antenna systems,
we propose non-coherent schemes for both amplify-and forward (AF) and decode-and-forward (DF) where the channel state information is not required. These new schemes are counterparts of the traditional non-coherent detection in point to point communications. The difficulty with differential modulation design in TWRC is that the received signal is a mixture of the signals from both source terminals. We derive maximum likelihood (ML) detectors
for both AF and DF. The DF protocol can be considered as
performing differential network coding at the physical layer. In addition, we propose several suboptimal alternatives including decision feedback and prediction based detectors. All these strategies work well as evidenced by simulation results. We also extend the schemes to the multiple-antenna case and provide design criterion of differential unitary space time modulation.https://authors.library.caltech.edu/records/f6w93-f7z76Memoryless Relay Strategies for Two-Way Relay Channels: Performance Analysis and Optimization
https://resolver.caltech.edu/CaltechAUTHORS:20100629-080753182
Authors: {'items': [{'id': 'Cui-Tao', 'name': {'family': 'Cui', 'given': 'Tao'}}, {'id': 'Ho-Tracey', 'name': {'family': 'Ho', 'given': 'Tracey'}}, {'id': 'Kliewer-J', 'name': {'family': 'Kliewer', 'given': 'Jörg'}}]}
Year: 2008
DOI: 10.1109/ICC.2008.222
We consider relaying strategies for two-way relay channels, where two terminals transmits simultaneously to each other with the help of relays. A memoryless system is considered, where the signal transmitted by a relay depends only on its last received signal. For binary antipodal signaling, we analyze and optimize the performance of existing amplify and forward (AF) and absolute (abs) decode and forward (ADF) for two- way AWGN relay channels. A new abs-based AF (AAF) scheme is proposed, which has better performance than AF. In low SNR, AAF performs even better than ADF. Furthermore, a novel estimate and forward (EF) strategy is proposed which performs better than ADF. More importantly, we optimize the relay strategy within the class of abs-based strategies via functional analysis, which minimizes the average probability of error over all possible relay functions. The optimized function is shown to be a Lambert's W function parameterized on the noise power and the transmission energy. The optimized function behaves like AAF in low SNR and like ADF in high SNR, resp., where EF behaves like the optimized function over the whole SNR range.https://authors.library.caltech.edu/records/er5yr-v4323Some results on relay strategies for memoryless two-way relay channels
https://resolver.caltech.edu/CaltechAUTHORS:20170418-174812677
Authors: {'items': [{'id': 'Cui-Tao', 'name': {'family': 'Cui', 'given': 'Tao'}}, {'id': 'Ho-Tracey', 'name': {'family': 'Ho', 'given': 'Tracey'}}, {'id': 'Kliewer-J', 'name': {'family': 'Kliewer', 'given': 'Jörg'}}]}
Year: 2008
DOI: 10.1109/ITA.2008.4601042
We consider relaying strategies for memoryless two-way relay channels, where the signal transmitted by a relay depends only on its previously received signal. For binary antipodal signaling under the general case of different SNRs on the terminal-relay channels, we consider two classes of relay strategies: abs-based strategies in which the processing at the relay is solely based on the absolute value of the received signal, and non-abs-based strategies. We analyze and optimize the performance of existing and new schemes for two-way relay channels under an average power constraint, including abs-based and non-abs-based versions of amplify and forward (AF), decode and forward (DF), and estimate and forward (EF). Additionally, we optimize the relay function via functional analysis such that the average probability of error is minimized in the high signal-to-noise ratio (SNR) regime. Finally, we show that all these results can also be generalized to higher order constellations.https://authors.library.caltech.edu/records/5vkxt-9t355Energy Efficient Opportunistic Network Coding for Wireless Networks
https://resolver.caltech.edu/CaltechAUTHORS:20100707-141558183
Authors: {'items': [{'id': 'Cui-Tao', 'name': {'family': 'Cui', 'given': 'Tao'}}, {'id': 'Chen-Lijun', 'name': {'family': 'Chen', 'given': 'Lijun'}}, {'id': 'Ho-Tracey', 'name': {'family': 'Ho', 'given': 'Tracey'}}]}
Year: 2008
DOI: 10.1109/INFOCOM.2008.81
We consider energy efficient network coding design in wireless networks with multiple unicast sessions. Our approach decomposes multiple unicast sessions into a superposition of multicast and unicast sessions, with coding occurring only within each session. We give an optimization approach that is more general than the existing poison-remedy optimization formulation. For the case of wireless, we consider XOR coding and give an achievable rate region for a primary interference model. To simplify network operation, we give an oblivious backpressure algorithm which does not optimize overhearing of transmissions, and a practical protocol called COPR based on the oblivious backpressure algorithm. Simulation experiments show that COPR largely reduces network power consumption over existing algorithms.https://authors.library.caltech.edu/records/m50vk-hrr38Maximum likelihood channel estimation in decode-and-forward relay networks
https://resolver.caltech.edu/CaltechAUTHORS:20170404-174823799
Authors: {'items': [{'id': 'Gao-Feifei', 'name': {'family': 'Gao', 'given': 'Feifei'}}, {'id': 'Cui-Tao', 'name': {'family': 'Cui', 'given': 'Tao'}}, {'id': 'Nallanathan-A', 'name': {'family': 'Nallanathan', 'given': 'Arumugam'}}]}
Year: 2008
DOI: 10.1109/ISIT.2008.4595184
In this paper, we provide a complete study on the training based channel estimation for relay networks that employ the decode-and-forward (DF) scheme. Since multiple relay nodes are geographically distributed over the service region, channel estimation is different from the traditional way in that each relay has its own individual power constraint. We consider the maximum likelihood (ML) channel estimation and derive closed form solutions for the optimal training as well as for the optimal power allocation. It is seen that the optimal power allocation follows a multi-level waterfilling structure.https://authors.library.caltech.edu/records/9as92-1rz46On multiple access random medium access control
https://resolver.caltech.edu/CaltechAUTHORS:20100816-095201318
Authors: {'items': [{'id': 'Cui-Tao', 'name': {'family': 'Cui', 'given': 'Tao'}}, {'id': 'Ho-Tracey', 'name': {'family': 'Ho', 'given': 'Tracey'}}]}
Year: 2009
DOI: 10.1109/ISIT.2009.5205457
In this paper, we develop a new class of medium access control protocol, which allows each user to transmit at different data rates chosen randomly from an appropriately determined set of rates. By using successive interference cancellation, multiple packets can be received simultaneously. In slotted Aloha type Gaussian networks, we show that the achievable total throughput of the proposed protocol is at least a constant fraction of the mac sum rate when the number of transmission rates at each node is equal to the number of users in the network. We also study the case when only a limited number of transmission rates is available at each node. Extension to rate splitting is discussed. Simulation results show that the proposed protocol can achieve a significant throughput gain over the conventional Aloha.https://authors.library.caltech.edu/records/ccp5e-02z13Achievable rate and optimal physical layer rate allocation in interference-free wireless networks
https://resolver.caltech.edu/CaltechAUTHORS:20100816-100837500
Authors: {'items': [{'id': 'Cui-Tao', 'name': {'family': 'Cui', 'given': 'Tao'}}, {'id': 'Ho-Tracey', 'name': {'family': 'Ho', 'given': 'Tracey'}}, {'id': 'Kliewer-J', 'name': {'family': 'Kliewer', 'given': 'Jörg'}}]}
Year: 2009
DOI: 10.1109/ISIT.2009.5205903
We analyze the achievable rate in interference-free
wireless networks with physical layer fading channels and
orthogonal multiple access. As a starting point, the point-to-point
channel is considered. We find the optimal physical and network
layer rate trade-off which maximizes the achievable overall rate
for both a fixed rate transmission scheme and an improved
scheme based on multiple virtual users and superposition coding.
These initial results are extended to the network setting, where,
based on a cut-set formulation, the achievable rate at each node
and its upper bound are derived. We propose a distributed
optimization algorithm which allows to jointly determine the
maxim um achievable rate, the optimal physical layer rates on
each network link, and an opportunistic back-pressure-type
routing strategy on the network layer. This inherently justifies
the layered architecture in existing wireless networks. Finally,
we show that the proposed layered optimization approach can
achieve almost all of the ergodic network capacity in high SNR.https://authors.library.caltech.edu/records/jh766-y0w46Optimal Quantization in Energy-Constrained Sensor
Networks under Imperfect Transmission
https://resolver.caltech.edu/CaltechAUTHORS:20100511-151403304
Authors: {'items': [{'id': 'Zhang-Li', 'name': {'family': 'Zhang', 'given': 'Li'}}, {'id': 'Cui-Tao', 'name': {'family': 'Cui', 'given': 'Tao'}}, {'id': 'Ho-Tracey', 'name': {'family': 'Ho', 'given': 'Tracey'}}, {'id': 'Zhang-Xian-Da', 'name': {'family': 'Zhang', 'given': 'Xian-Da'}}]}
Year: 2009
DOI: 10.1109/CISS.2009.5054792
This paper addresses the optimization of quantization at local sensors under strict energy constraint and imperfect transmission to improve the reconstruction performance at the fusion center in the wireless sensor networks (WSNs). We present optimized quantization scheme including the optimal quantization bit rate and the optimal transmission power allocation among quantization bits for BPSK signal and binary orthogonal signal with envelope detection, respectively. The optimization of the quantization is formulated as a convex problem and the optimal solution is derived analytically in both cases. Simulation results demonstrate the effectiveness of our proposed quantization schemes.https://authors.library.caltech.edu/records/1ehj9-an320Throughput Optimization in High Speed Downlink Packet Access (HSDPA)
https://resolver.caltech.edu/CaltechAUTHORS:20100907-094109886
Authors: {'items': [{'id': 'Cui-Tao', 'name': {'family': 'Cui', 'given': 'Tao'}}, {'id': 'Lu-Feng', 'name': {'family': 'Lu', 'given': 'Feng'}}, {'id': 'Goteti-A', 'name': {'family': 'Goteti', 'given': 'Anil'}}, {'id': 'Sethuraman-V', 'name': {'family': 'Sethuraman', 'given': 'V.'}}, {'id': 'Rao-S-P', 'name': {'family': 'Rao', 'given': 'S. P.'}}, {'id': 'Subrahmanya-P', 'name': {'family': 'Subrahmanya', 'given': 'P.'}}]}
Year: 2009
DOI: 10.1109/ICC.2009.5199527
In this paper, we investigate throughput optimization
in High Speed Downlink Packet Access (HSDPA). Specifically,
we propose offline and online algorithms for adjusting
the Channel Quality Indicator (CQI) used by the network to
schedule data transmission. In the offline algorithm, a given
target BLER is achieved by adjusting CQI based on ACK/NAK
history. By sweeping through different target BLERs, we can
find the throughput optimal BLER offline. This algorithm could
be used not only to optimize throughput but also to enable fair
resource allocation among mobile users in HSDPA. In the online
algorithm, the CQI offset is adapted using an estimated short
term throughput gradient without specifying a target BLER. An
adaptive stepsize mechanism is proposed to track temporal variation
of the environment. We investigate convergence behavior
of both algorithms. Simulation results show that the proposed
offline algorithm can achieve the given target BLER with good
accuracy. Both algorithms yield up to 30% HSDPA throughput
improvement over that with 10% target BLER.https://authors.library.caltech.edu/records/hhmpy-ndw48