We address the single-source-destination routing problem in a mesh network with a broadcast channel, time-division multiplexing (TDM) and no spatial reuse, which is a special type of the PLC channel. First, the outer ...
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ISBN:
(纸本)9781509023899
We address the single-source-destination routing problem in a mesh network with a broadcast channel, time-division multiplexing (TDM) and no spatial reuse, which is a special type of the PLC channel. First, the outer bound on the achievable data rate is evaluated. We show that the routing protocols (RPs) with static routing do not allow approaching this data rate limit. Then, we study RP with opportunistic routing (ORP). We show that its main disadvantage, extensive feedback, can be successively reduced when using network coding (NC). We propose the basic routing rules (BRR) based on ORP with NC. Then, we demonstrate that the data rate achievable with BRR approaches the outer bound when the coding window increases. Finally, we provide the simulation results, which prove the concept. In the considered scenarios, BRR allow the data rate up to 10% higher than RPs with static routing, which is just 5-10% away from the theoretical outer bound limit.
The problem of joint resource allocation and relay selection is studied for bidirectional LTE-advanced relay networks. The bidirectional communication between user equipment (UE) and eNodeB (eNB) is performed via dire...
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The problem of joint resource allocation and relay selection is studied for bidirectional LTE-advanced relay networks. The bidirectional communication between user equipment (UE) and eNodeB (eNB) is performed via direct transmission, cooperative relaying (CoR), or a combination of network coding (NC) and CoR (NC/CoR). In this paper, an enhanced three-time-slot per cycle time-division duplexing (TDD) scheme is proposed for LTE-Advanced frame architecture to accommodate a hybrid transmission scheme. More specifically, we formulate the problem of joint resource assignment, relay selection, and bidirectional transmission scheme selection as a combinatorial optimization problem with the objective to maximize the total product of backlog and rate (back-pressure principle). Two approaches are considered to solve our combinatorial optimization problem. First, a graph-based framework is proposed in which the problem is transformed into a maximum weighted Clique problem (MWCP). In addition, our problem is also transformed into a three-dimensional assignment problem (3DAP) which is solved using a hybrid ant colony optimization (ACO) algorithm. Using simulations, it is concluded that the hybrid transmission scheme outperforms all conventional nonhybrid schemes. Moreover, the simulation results confirm that while the two proposed solutions provide similar results, the ACO algorithm is faster due to its lower complexity.
In this paper, we derive the capacity of the deterministic relay networks with relay messages. We consider a network that consists of five nodes, four of which can only communicate via the fifth one. However, the fift...
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In this paper, we derive the capacity of the deterministic relay networks with relay messages. We consider a network that consists of five nodes, four of which can only communicate via the fifth one. However, the fifth node is not merely a relay as it may exchange private messages with the other network nodes. First, we develop an upper bound on the capacity region based on the notion of a single-sided genie. In the course of the achievability proof, we also derive the deterministic capacity of a four-user relay network (without private messages at the relay). The capacity achieving schemes use a combination of two network coding techniques: the simple ordering scheme and detour scheme. In the simple ordering scheme, we order the transmitted bits at each user such that the bi-directional messages will be received at the same channel level at the relay, while the basic idea behind the detour scheme is that some parts of the message follow an indirect paths to their respective destinations. This paper, therefore, serves to show that user cooperation and network coding can enhance throughput, even when the users are not directly connected to each other. Finally, we make a conjecture about the capacity region of the general K-node relay network with relay messages. Copyright (c) 2016 John Wiley & Sons, Ltd.
Analog network coding (ANC) is effective in improving spectrum efficiency. To coordinate ANC among multiple nodes without relying on complicated scheduling algorithm and network optimization, a new random access MAC p...
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Analog network coding (ANC) is effective in improving spectrum efficiency. To coordinate ANC among multiple nodes without relying on complicated scheduling algorithm and network optimization, a new random access MAC protocol, called ANC-ERA, is developed to dynamically form ANC-cooperation groups in an ad hoc network. ANC-ERA includes several key mechanisms to maintain high performance in medium access. First, network allocation vectors (NAV) of control frames are properly set to avoid over-blocking of channel access. Second, a channel occupation frame (COF) is added to protect vulnerable periods during the formation of ANC cooperation. Third, an ACK diversity mechanism is designed to reduce potentially high ACK loss probability in ANC-based wireless networks. Since forming an ANC cooperation relies on bi-directional traffic between the initiator and the cooperator, the throughput gain from ANC drops dramatically if bi-directional traffic is not available. To avoid this issue, the fourth key mechanism, called flow compensation, is designed to form different types of ANC cooperation among neighboring nodes of the initiator and the cooperator. Both theoretical analysis and simulations are conducted to evaluate ANC-ERA. Performance results show that ANC-ERA works effectively in ad hoc networks and significantly outperforms existing random access MAC protocols.
Because of the broadcast and overhearing capability of wireless networks, network coding can greatly improve throughput in wireless networks. However, our investigation of existing inter-session network coding protoco...
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Because of the broadcast and overhearing capability of wireless networks, network coding can greatly improve throughput in wireless networks. However, our investigation of existing inter-session network coding protocols found that the short-term unfairness that existed in 802.11-based medium access control (MAC) protocols actually decreases the coding opportunity, which in turn compromises the throughput gain of network coding. To alleviate the negative impact of this unfairness, we propose a coding-aware cross-layer heuristic approach to optimize the coordination of network coding and MAC layer protocol, named Faircoding, which can significantly increase coding opportunities for inter-session network coding through a fair short-term traffic allocation for different coding flows. Experiment evaluation shows that the proposed mechanism can bring more coding opportunities and improve the total throughput of wireless mesh networks by up to 20%, compared with the coding mechanism, without considering the negative impact of the short-term unfairness. Copyright (c) 2015 John Wiley & Sons, Ltd.
network coding (NC) can greatly improve the performance of wireless mesh networks (WMNs) in terms of throughput and reliability, and so on. However, NC generally performs a batch-based transmission scheme, the main dr...
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network coding (NC) can greatly improve the performance of wireless mesh networks (WMNs) in terms of throughput and reliability, and so on. However, NC generally performs a batch-based transmission scheme, the main drawback of this scheme is the inevitable increase in average packet delay, that is, a large batch size may achieve higher throughput but also induce larger average packet delay. In this work, we put our focus on the tradeoff between the average throughput and packet delay;in particular, our ultimate goal is to maximize the throughput for real-time traffic under the premise of diversified and time-varying delay requirements. To tackle this problem, we propose DCNC, a delay controlled network coding protocol, which can improve the throughput for real-time traffic by dynamically controlling the delay in WMNs. To define an appropriate control foundation, we first build up a delay prediction model to capture the relationship between the average packet delay and the encoding batch size. Then, we design a novel freedom-based feedback scheme to efficiently reflect the reception of receivers in a reliable way. Based on the predicted delay and current reception status, DCNC utilizes the continuous encoding batch size adjustment to control delay and further improve the throughput. Extensive simulations show that, when faced with the diversified and time-varying delay requirements, DCNC can constantly fulfill the delay requirements, for example, achieving over 95% efficient packet delivery ratio (EPDR) in all instances under good channel quality, and also obtains higher throughput than the state-of-art protocol. Copyright (C) 2014 John Wiley & Sons, Ltd.
network coding is an important cloud storage technique, which can recover data with small repair bandwidth and high reliability compared to the existing erasure coding and replication methods. However, regardless of w...
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network coding is an important cloud storage technique, which can recover data with small repair bandwidth and high reliability compared to the existing erasure coding and replication methods. However, regardless of which data recovery technique is used, the repaired data in a geographically distributed cloud storage system are easy to be eavesdropped at the transmission link between the local datacenter and its remote backup site. This kind of network security issue is called link eavesdropping in this paper. For a network coded cloud storage system, we propose a systematic design methodology to determine the important data recovery system parameters for any specified security level. Through analysis, we present the performance curves to relate the remote repair bandwidth and the number of coded data fragments. Consequently, all the important system parameters of a network coded data recovery system, including the number of storage nodes and the link capacity between the datacenter and the backup site, can be precisely designed for satisfying different security level requirements.
In this letter, we consider heterogeneous wireless network with storage capable wireless access points, and study the video delivery problem for video files that can be encoded with different layers in various qualiti...
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In this letter, we consider heterogeneous wireless network with storage capable wireless access points, and study the video delivery problem for video files that can be encoded with different layers in various qualities. We introduce a framework for the joint optimization of video file coding, cache content placement, and rate allocation for users with different quality requirements. We formulate the problem as a linear programming using network coding with non-overlapping windows and expanding windows, and the aim is to minimize the traffic load pressure on the base station. Simulation results show that significant caching and coding gains can be achieved with the proposed framework, which translates into a reduction of the extra traffic load on base station.
Under the assumption that each node has delayed channel state information at transmitter (D-CSIT), this letter studies the achievable degrees of freedom (DOF) for K-user multiple-input-multiple-output (MIMO) Y channel...
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Under the assumption that each node has delayed channel state information at transmitter (D-CSIT), this letter studies the achievable degrees of freedom (DOF) for K-user multiple-input-multiple-output (MIMO) Y channel in frequency division duplex (FDD) systems, where each user exchanges messages with other K - 1 users simultaneously via an intermediate relay. We propose a new retrospective network coding alignment (RNCA) scheme and derive the closed-form expression for achievable DOF.
A queue stability analysis in a wireless multicast network with packet erasure channels is studied in this letter. In particular, a new queuing model consisting of several sub-queues is introduced, where each packet i...
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A queue stability analysis in a wireless multicast network with packet erasure channels is studied in this letter. In particular, a new queuing model consisting of several sub-queues is introduced, where each packet in a sub-queue is associated with an index set indicating its intended users. Our objective is to maximize the input rate under the queue stability constraints. We formulate it as a linear programming problem and propose a network coding-based packet scheduling scheme that finds the optimal solution. Finally, the simulation results corroborate our method.
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