This paper proposes an XOR physical layer network coding (XOR-PLNC) with non-linear precoding for quadrature amplitude modulations (QAMs) in bi-directional MIMO relay systems. The proposed XOR-PLNC applies power loadi...
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This paper proposes an XOR physical layer network coding (XOR-PLNC) with non-linear precoding for quadrature amplitude modulations (QAMs) in bi-directional MIMO relay systems. The proposed XOR-PLNC applies power loading in order to improve the transmission performance. The proposed XOR-PLNC introduces a modulus adapted to channel gains. Moreover, the modulus is further reduced in cooperation with modulo operation which the non-linear precoding employs for improvement of transmission power efficiency. The use of the reduced modulus improves the energy efficiency of the signal transmission, which improves the transmission performance in the proposed XOR-PLNC. The performance is evaluated by computer simulations in bi-directional MIMO relay channels with 16QAM to 1024QAM.
network coding is an efficient means to improve the spectrum efficiency of satellite communications. However, its resilience to eavesdropping attacks is not well understood. This paper studies the confidentiality issu...
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network coding is an efficient means to improve the spectrum efficiency of satellite communications. However, its resilience to eavesdropping attacks is not well understood. This paper studies the confidentiality issue in a bidirectional satellite network consisting of two mobile users who want to exchange message via a multibeam satellite using the XOR network coding protocol. We aim to maximize the sum secrecy rate by designing the optimal beamforming vector along with optimizing the return and forward link time allocation. The problem is nonconvex, and we find its optimal solution using semidefinite programming together with a 1-D search. For comparison, we also solve the sum secrecy rate maximization problem for a conventional reference scheme without using network coding. Simulation results using realistic system parameters demonstrate that the bidirectional scheme using network coding provides considerably higher secrecy rate compared with that of the conventional scheme.
This paper considers the problems of minimizing the completion time and reducing decoding complexity for relay-aided wireless broadcast. Both network coding and scheduling problems are considered. A deterministic netw...
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This paper considers the problems of minimizing the completion time and reducing decoding complexity for relay-aided wireless broadcast. Both network coding and scheduling problems are considered. A deterministic network coding algorithm is designed to select innovative encoding vectors, which is applicable to both the base station and the relay. The proposed algorithm can reduce decoding complexity significantly by selecting sparse encoding vectors. Integrating with the proposed network coding algorithm, a scheduling scheme based on dynamic programming is proposed, which is proved to be optimal in terms of minimizing expected completion time. Considering the size of state space and computational complexity of dynamic programming, a greedy scheduling algorithm is also proposed for practical implementation. Simulation shows that the proposed network coding algorithm and scheduling schemes work very well both in reducing completion time and in decoding complexity.
This paper investigates network coding with full diversity and a high rate for improving the reliability of wireless communications against the co-channel interference. We consider a cellular network composed of two u...
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This paper investigates network coding with full diversity and a high rate for improving the reliability of wireless communications against the co-channel interference. We consider a cellular network composed of two user terminals that are intended to communicate with a common base station (BS), where a two-way relay node is used to assist the bidirectional communications between the users and BS. We propose an opportunistic network coding (ONC) scheme with the two-way relay, called two-way ONC, which operates depending on whether or not the relay node successfully decodes data packets of the user terminals and BS. Closed-form outage probability expressions of the uplink transmission (from users to BS) and downlink transmission (from BS to users) are derived for the proposed two-way ONC scheme in the presence of co-channel interference over Rayleigh fading channels. We also develop the diversity-multiplexing tradeoff (DMT) of the two-way ONC scheme and show that it obtains the full diversity and an increased multiplexing gain, as compared with conventional one-way relay methods. Additionally, numerical outage probability results demonstrate that the proposed two-way ONC scheme outperforms the conventional one-way relay approaches in terms of improving the communication's reliability against co-channel interference.
Reliable multicast, the lossiess dissemination of data from one sender to a group of receivers, has a wide range of important applications in wireless networks. In this paper, we are interested in the reliable single-...
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Reliable multicast, the lossiess dissemination of data from one sender to a group of receivers, has a wide range of important applications in wireless networks. In this paper, we are interested in the reliable single-hop wireless multicast. As the wireless channel is inherently error prone, it is challenging to achieve high channel utilization in reliable wireless multicast. Most schemes proposed by now for reliable single-hop wireless multicast share the same weakness in that an entire frame will be retransmitted even if it has single error bit. To alleviate this problem, this paper presents an efficient reliable multicast scheme based on block-level ARQ and network coding technique. The new scheme breaks the data stream into blocks and retransmits only erroneous blocks (rather than the entire corrupted frame), where the novel network coding technique is further adopted to minimize the total number of block retransmissions. The theoretical analysis and simulation are conducted to demonstrate the performance of the new scheme and also some typical available schemes in terms of their bandwidth efficiency. The simulation and theoretical results indicate that new reliable wireless multicast scheme can significantly enhance the channel utilization, especially in the scenarios where bit error rate is high and the number of receivers is large. (C) 2012 Elsevier. B.V. All rights reserved.
This paper studies the recovery from multiple node failures in distributed storage systems. We design a mutually cooperative recovery (MCR) mechanism for multiple node failures. Via a cut-based analysis of the informa...
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This paper studies the recovery from multiple node failures in distributed storage systems. We design a mutually cooperative recovery (MCR) mechanism for multiple node failures. Via a cut-based analysis of the information flow graph, we obtain a lower bound of maintenance bandwidth based on MCR. For MCR, we also propose a transmission scheme and design a linear network coding scheme based on (n, k) strong-MDS code, which is a generalization of (n, k) MDS code. We prove that the maintenance bandwidth based on our transmission and coding schemes matches the lower bound, so the lower bound is tight and the transmission scheme and coding scheme for MCR are optimal. We also give numerical comparisons of MCR with other redundancy recovery mechanisms in storage cost and maintenance bandwidth to show the advantage of MCR.
In 2010, Silva et at. studied certain classes of finite-field matrix channels in order to model random linear network coding where exactly t random errors are introduced. In this paper, we consider a generalization of...
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In 2010, Silva et at. studied certain classes of finite-field matrix channels in order to model random linear network coding where exactly t random errors are introduced. In this paper, we consider a generalization of these matrix channels where the number of errors is not required to be constant, indeed the number of errors may follow any distribution. We show that a capacity-achieving input distribution can always be taken to have a very restricted form (the distribution should be uniform given the rank of the input matrix). This result complements, and is inspired by a paper of Nobrega et al., which establishes a similar result for a class of matrix channels that model network coding with link erasures. Our result shows that the capacity of our channels can be expressed as maximization over probability distributions on the set of possible ranks of input matrices: a set of linear rather than exponential size.
In the paper, we investigate the information spread problem in a joint vehicle-to-infrastructure (V2I) and vehicle-to-vehicle (V2V) communication system. A scene is considered where more information centers (or base s...
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In the paper, we investigate the information spread problem in a joint vehicle-to-infrastructure (V2I) and vehicle-to-vehicle (V2V) communication system. A scene is considered where more information centers (or base stations) are allocated along the road so that the information centers are able to broadcast timely messages to vehicles within the range of the broadcast signal of each base station, which we shall refer to as broadcast zone. The seamless information spread is used to guarantee that messages are correctly received by each vehicle, regardless of whether it pulls into broadcast zones or not. We first derive the maximum throughput of the V2I downlink system for both additive white Gaussian noise (AWGN) channels and Rayleigh fading channels with Doppler effects. A measurement-based algorithm to estimate the throughput is also proposed. We then discuss the maximum achievable amount of information that can be relayed forward along a vehicular stream. A network coding technique will then be proposed to cancel the interference caused by relay signals to vehicles that are receiving messages from the corresponding information center. These theoretical results will give more insight into the vehicular communication system design.
Mobile molecular communication via diffusion (MCvD) has attracted lots of attentions due to its time-varying channels. In this paper, we investigate a mobile two-way MCvD model, which consists of two mobile source nan...
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Mobile molecular communication via diffusion (MCvD) has attracted lots of attentions due to its time-varying channels. In this paper, we investigate a mobile two-way MCvD model, which consists of two mobile source nanomachines and a mobile relay nanomachine. The amplify-and-forward (AF) relaying and analog network coding (ANC) are utilized to implement the exchange of information between two source nanomachines in this model. To explore the performance of the mobile two-way MCvD system, we first adopt the depleted molecule shift keying (D-MoSK) modulation, and then the mathematical expressions of symbol error probability (SEP) and mutual information are derived by using AF and ANC scheme on the basis of maximum a posteriori (MAP) probability detection. Finally, we present the numerical and simulation results. Compared with the AF-No-ANC scheme which is without use of ANC scheme, the scheme of combining AF and ANC can significantly improve the performance of SEP and mutual information. Moreover, the D-MoSK modulation outperforms the molecule shift keying (MoSK) modulation for this mobile two-way MCvD system. In addition, we propose the evaluation and discussion about the impacts of several important parameters on the performance of this system. These results can be used to design mobile two-way MCvD system with lower SEP and higher mutual information.
Mobile cloud applications have become extremely popular in the last years. Location-based services, navigation, online gaming and social networking are a representative set of "always on" cloud applications ...
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ISBN:
(纸本)9781479966646
Mobile cloud applications have become extremely popular in the last years. Location-based services, navigation, online gaming and social networking are a representative set of "always on" cloud applications in which the same or partially overlapping content is delivered to multiple users. network coding is a well matching solution to improve content delivery. In this paper we propose the vNC-CELL technique, which uses network coding to combine information flows carrying the same or overlapping content that has to be delivered to co-located users. vNC-CELL executes coding functionalities in a mobile cloud through virtualization as these operations are computationally intensive if performed locally at the base station. Performance evaluation obtained from NS-3 simulations confirms vNC-CELL ability to improve network throughput and reduce download times for the users.
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