| 1. |
- Adams, David C., et al.
(författare)
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Delay constrained throughput-reliability tradeoff in network-coded wireless systems
- 2014
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Konferensbidrag (refereegranskat)abstract
- We investigate the performance of delay constrained data transmission over wireless networks without end-to-end feedback. Forward error-correction coding (FEC) is performed at the bit level to combat channel distortions and random linear network coding (RLNC) is performed at the packet level to recover from packet erasures. We focus on the scenario where RLNC re-encoding is performed at intermediate nodes and we assume that any packet that contains bit errors after FEC decoding can be detected and erased. To facilitate explicit characterization of data transmission over network-coded wireless systems, we propose a generic two-layer abstraction of a network that models both bit/symbol-level operations at the lower layer (termed PHY-layer) over several heterogeneous links and packet-level operations at the upper layer (termed NET-layer). Based on this model, we propose a network reduction method to characterize the throughput-reliability function of the end-to-end transmission. Our approach not only reveals an explicit tradeoff between data delivery rate and reliability, but also provides an intuitive visualization of the bottlenecks within the underlying network. We illustrate our approach via a point-to-point link and a relay network and highlight the advantages of this method over capacity-based approaches.
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| 2. |
- Du, Jinfeng, et al.
(författare)
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Capacity Bounds for Backhaul-Supported Wireless Multicast Relay Networks with Cross-Links
- 2011
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Ingår i: IEEE INTERNATIONAL CONFERENCE ON COMMUNICATIONS (ICC), 2011. - NEW YORK : IEEE conference proceedings. - 9781612842325 - 9781612842318 ; , s. 1-5
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Konferensbidrag (refereegranskat)abstract
- We investigate the capacity bounds for a wireless multicast relay network where two sources simultaneously multicast to two destinations through Gaussian channels with the help of a full-duplex relay node. All the individual channel gains are assumed to be time-invariant and known to every nodes in the network. The transmissions from two sources and from the relay use the same channel resource (i.e. co-channel transmission) and the two source nodes are connected with an orthogonal error-free backhaul. This multicast relay network is generic in the sense that it can be extended to more general networks by tuning the channel gains within the range [0, ∞). By extending the proof of the converse developed by Cover and El Gamal for the Gaussian relay channel, we characterize the cut-set bound for this multicast relay network. We also present a lower bound by using decoding-and-forward relaying combined with network beam-forming.
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| 3. |
- Du, Jinfeng, et al.
(författare)
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Capacity bounds for relay-aided wireless multiple multicast with backhaul
- 2010
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Ingår i: 2010 International Conference on Wireless Communications and Signal Processing, WCSP 2010. - NEW YORK : IEEE conference proceedings. - 9781424475568 - 9781424475544 ; , s. 1-5
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Konferensbidrag (refereegranskat)abstract
- We investigate the capacity bounds for relay-aided two-source two-destination wireless networks with backhaul support between source nodes. Each source multicasts its own message to all destinations with the help of an intermediate relay node, which is full-duplex and shared by both sources. We are aiming to characterize the capacity region of this model given discrete memoryless Gaussian channels. We establish three capacity upper bounds by relaxing the cut-set bound, and by extending two capacity bounds originally derived for MIMO relay channels. We also present one lower bound by using decoding-and-forward relaying combined with network beam-forming.
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| 4. |
- Du, Jinfeng, et al.
(författare)
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Classic OFDM Systems and Pulse Shaping OFDM/OQAM Systems
- 2007
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- In this report, we provide a comparative study of state-of-the-art in Orthogonal Frequency Division Multiplexing (OFDM) techniques with orthonormal analysis and synthesis basis. Two main categories, OFDM/QAM which adopts base-band Quadrature Amplitude Modulation (QAM) and rectangular pulse shape, and OFDM/OQAM which uses baseband offset QAM and various pulse shapes, are intensively reviewed. OFDM/QAM can provide high data rate communication and effectively remove intersymbol interference (ISI) by employing guard interval, which costs a loss of spectral efficiency and increases power consumption. Meanwhile it remains very sensitive to frequency offset which causes inter-carrier interference (ICI). In order to achieve better spectral efficiency and reducing combined ISI/ICI, OFDM/OQAM using well designed pulses with proper Time Frequency Localization (TFL) is of great interest. Various prototype functions, such as rectangular, half cosine, Isotropic Orthogonal Transfer Algorithm (IOTA) function and Extended Gaussian Functions (EGF) are discussed and simulation results are provided to illustrate the TFL properties by the ambiguity function and the interference function.
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| 5. |
- Du, Jinfeng, et al.
(författare)
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Comparison of CP-OFDM and OFDM/OQAM in doubly dispersive channels
- 2007
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Ingår i: PROCEEDINGS OF FUTURE GENERATION COMMUNICATION AND NETWORKING, WORKSHOP PAPERS, VOL 2. - LOS ALAMITOS : IEEE conference proceedings. - 9780769530482 ; , s. 207-211
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Konferensbidrag (refereegranskat)abstract
- In this paper we compare the performance of cyclic prefix based OFDM (CP-OFDM) system and OFDM/offset QAM (OFDM/OQAM) system in doubly dispersive channels, by investigating the signal reconstruction perfectness, time and frequency dispersion robustness, and sensitivity to frequency offset. Both analysis and simulation results show that various parameter adaptations can be made with respect to the channel state information to improve the system performance.
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| 6. |
- Du, Jinfeng, et al.
(författare)
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Cooperative Network Coding Strategies for Wireless Relay Networks with Backhaul
- 2011
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Ingår i: IEEE Transactions on Communications. - 0090-6778 .- 1558-0857. ; 59:9, s. 2502-2514
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Tidskriftsartikel (refereegranskat)abstract
- We investigate cooperative network coding strategies for relay-aided two-source two-destination wireless networks with a backhaul connection between the source nodes. Each source multicasts information to all destinations using a shared relay. We study cooperative strategies based on different network coding schemes, namely, finite field and linear network coding, and lattice coding. To further exploit the backhaul connection, we also propose network coding based beamforming. We measure the performance in term of achievable rates over Gaussian channels, and observe significant gains over benchmark schemes. We derive the achievable rate regions for these schemes and find the cut-set bound for our system. We also show that the cut-set bound can be achieved by network coding based beamforming when the signal-to-noise ratios lie in the sphere defined by the source-relay and relay-destination channel gains.
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| 7. |
- Du, Jinfeng, et al.
(författare)
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Cooperative strategies for relay-aided multi-cell wireless networks with backhaul
- 2010
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Ingår i: 2010 IEEE Information Theory Workshop, ITW 2010 - Proceedings. - NEW YORK : IEEE conference proceedings. - 9781424482627 - 9781424482634 ; , s. 1-5
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Konferensbidrag (refereegranskat)abstract
- We investigate cooperative strategies for relay-aided multi-source multi-destination wireless networks with backhaul support. Each source multicasts information to all destinations using a shared relay. We study cooperative strategies based on different network coding (NC) schemes, namely, finite field NC (FNC), linear NC (LNC), and lattice coding. To further exploit the backhaul connection, we also propose NC-based beam-forming (NBF). We measure the performance in term of achievable rates over Gaussian channels and observe significant gains over a benchmark scheme. The benefit of using backhaul is also clearly demonstrated in most of scenarios.
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| 8. |
- Du, Jinfeng
(författare)
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Cooperative Strategies in Multi-Terminal Wireless Relay Networks
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Smart phones and tablet computers have greatly boosted the demand for services via wireless access points, keeping constant pressure on the network providers to deliver vast amounts of data over the wireless infrastructure. To enlarge coverage and enhance throughput, relaying has been adopted in the new generation of wireless communication systems, such as in the Long-Term Evolution Advanced standard, and will continue to play an important role in the next generation wireless infrastructure. Depending on functionality, relaying can be characterizing into three main categories: amplify-and-forward (AF), compression-and-forward (CF), and decode-and-forward (DF). In this thesis, we investigate different cooperative strategies in wireless networks when relaying is in use.We first investigate the capacity outer and inner bounds for a wireless multicast relay network where two sources, connected by error-free backhaul, multicast to two destinations with the help of a full-duplex relay node. For high-rate backhaul scenarios, we find the exact cut-set bound of the capacity region by extending the proof of the converse for the Gaussian relay channel. For low-rate backhaul scenarios, we present two genie-aided outer bounds by extending the previous proof and introducing two lemmas on conditional (co-)variance. Our inner bounds are derived from various cooperative strategies by combining DF/CF/AF relaying with network coding schemes. We also extend the noisy network coding scheme and the short-message noisy network coding approach to correlated sources. For low-rate backhaul, we propose a new coding scheme, partial-decode-and-forward based linear network coding. We derive the achievable rate regions for these schemes and measure the performance in term of achievable rates over Gaussian channels. By numerical investigation we observe significant gains over benchmark schemes and demonstrate that the gap between upper and lower bounds is in general not large. We also show that for high-rate backhaul, the cut-set bound can be achieved when the signal-to-noise ratios lie in the sphere defined by the source-relay and relay-destination channel gains.For wireless networks with independent noise, we propose a simple framework to get capacity outer and inner bounds based on the ``one-shot'' bounding models. We first extend the models for two-user broadcast channels to many-user scenarios and then establish the gap between upper and lower bounding models. For networks with coupled links, we propose a channel decoupling method which can decompose the network into overlapping multiple-access channels and broadcast channels. We then apply the one-shot models and create an upper bounding network with only bit-pipe connections. When developing the lower bounding network, we propose a two-step update of these models for each coupled broadcast and multiple-access channels. We demonstrate by some examples that the resulting upper bound is in general very good and the gap between the upper and lower bounds is usually not large.For relay-aided downlink scenarios, we propose a cooperation scheme by cancelling interference at the transmitter. It is indeed a symbol-by-symbol approach to one-dimension dirty paper coding (DPC). For finite-alphabet signaling and interference, we derive the optimal (in terms of maximum mutual information) modulator under a given power constraint. A sub-optimal modulator is also proposed by formulating an optimization problem that maximizes the minimum distance of the signal constellation, and this non-convex optimization problem is approximately solved by semi-definite relaxation. Bit-level simulation shows that the optimal and sub-optimal modulators can achieve significant gains over the Tomlinson-Harashima precoder (THP) benchmark and over non-DPC reference schemes, especially when the power of the interference is larger than the power of the noise.
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| 9. |
- Du, Jinfeng, et al.
(författare)
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Costa precoding in one dimension
- 2006
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Ingår i: 2006 IEEE International Conference on Acoustics, Speech, and Signal Processing. - : IEEE conference proceedings. - 142440469X ; , s. 717-720
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Konferensbidrag (refereegranskat)abstract
- We design an optimum modulator for the Costa (dirty-paper) precoding problem under the constraint of a binary signaling alphabet, and assuming the interference symbols belong to a binary constellation. We evaluate the performance of our technique in terms of the mutual information between the channel input and output, and compare it to that of Tomlinson-Harashima precoding (THP) with optimized parameters. We show that our optimal modulator is always better than THP. In many relevant scenarios, the performance difference is significant.
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| 10. |
- Du, Jinfeng, et al.
(författare)
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Cross-layer design of network-coded transmission with a delay constraint
- 2015
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Ingår i: Proceedings of IEEE International Workshop on Signal Processing Advances in Wireless Communications (SPAWC), 2015. - : IEEE. - 9781479919307 ; , s. 156-160
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Konferensbidrag (refereegranskat)abstract
- We investigate the cross-layer design of wireless networks where end-to-end data transmission is subject to delayconstraint and there is no end-to-end feedback. The transmission is coded by random linear network coding (RLNC) on packet level to recover from packet erasures and by forward error-correction coding (FEC) on bit level to combatchannel distortions. Based on the two-layer model developed by Adams et al. where the end-to-end coded transmission ischaracterized by a throughput-reliability function, we formulate the cross-layer design as a goodput optimizationproblem relax the integrality constraint. We show that for single-hop transmissions there exists a globally optimal operating point for the relaxed problem. For multiple-hop transmissions, the goodput function is component-wiseconcave with respect to the physical layer data rate over each individual link.
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