In this paper, a novel HARQ transmission scheme based on network coding is proposed for wireless unicast scenarios. Instead of retransmitting erroneous packets individually, a network coded packet constructed by the X...
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ISBN:
(纸本)9781467304375;9781467304368
In this paper, a novel HARQ transmission scheme based on network coding is proposed for wireless unicast scenarios. Instead of retransmitting erroneous packets individually, a network coded packet constructed by the XOR of two erroneous packets is transmitted similar to network coding. In order to fully exploit the network coded packet in combination with the previously received erroneous packets, soft combining methods with respect to Chase Combing (CC) and Incremental Redundancy (IR) are developed. The expected throughput gain of 33% for one retransmission for the proposed solution compared to common HARQ transmission is confirmed by LTE link-level simulations.
network coding helps maximize the network throughput. However, such schemes are also vulnerable to pollution attacks in which malicious forwarders inject polluted messages into the system. Traditional cryptographic so...
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ISBN:
(纸本)9781467325790
network coding helps maximize the network throughput. However, such schemes are also vulnerable to pollution attacks in which malicious forwarders inject polluted messages into the system. Traditional cryptographic solution, such as digital signatures, are not suited for network coding, in which nodes do not forward the original packets, but rather linear combinations of the data they received. We describe secure scheme that uses batch techniques and selective verification to efficiently verify the integrity of the received packets. We show that for real peer-to-peer networks, our scheme is much more efficient than previously suggested schemes.
When network coding is adopted to optimize transport performance of WMN networks, it has problems such as end to end delay and compatibility with wireless network environment emerge. With this in mind, this paper expl...
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ISBN:
(纸本)9780769549613;9781467358088
When network coding is adopted to optimize transport performance of WMN networks, it has problems such as end to end delay and compatibility with wireless network environment emerge. With this in mind, this paper explores transport technologies based on network coding and TCP Reno protocol and reveals these problems by simulations. End to end delay optimized method is proposed based on optimal block size of file transported. And an automatic tuning method for the redundancy factor R is also proposed based on congestion detection and link quality detection. Performance of all these contributions is evaluated by simulation results.
In order to improve broadcasting efficiency in LTEA system, a novel HARQ scheme with network coding (NC) technology is presented in this paper. The implementation level of XORing NC is selected based on LTE system, an...
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ISBN:
(纸本)9781467358293;9781467358309
In order to improve broadcasting efficiency in LTEA system, a novel HARQ scheme with network coding (NC) technology is presented in this paper. The implementation level of XORing NC is selected based on LTE system, and an XORing NC Combined (XNCC) strategy is developed to perform combined retransmission. The main idea of proposed scheme is to retransmit lost packets for multiple receivers simultaneously utilizing NC technology. Moreover, we extend the proposed scheme to relay broadcasting system. The simulation results illustrate that compared with traditional retransmission scheme, the average number of transmissions of the proposed NC-HARQ scheme can be sharply decreased, and the coding gains can be attributed to the potential advantage of NC technology.
In the literature, cooperative relaying and network coding have been used separately in improving performance of wireless MAC protocols. In this paper, we propose a novel scheme that combines both cooperative relaying...
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ISBN:
(纸本)9781467304375;9781467304368
In the literature, cooperative relaying and network coding have been used separately in improving performance of wireless MAC protocols. In this paper, we propose a novel scheme that combines both cooperative relaying and network coding for further performance improvement. The proposed scheme considers two challenges of network-coded cooperative MAC operating in a realistic wireless network. First, links in realistic networks inherently operate with different data rates due to varying channel conditions and distances between the nodes. Existing works do not consider this issue and consequently the coding advantage is not fully harnessed. In our proposed scheme, we integrate both network coding and multi-rate issues as a single optimization problem. Second, network coding used in existing works require costly and reliable feedback in order to harness the gain. Since realistic links are unreliable in nature, our proposed scheme uses a cyclic coding method instead of the traditional XOR coding. Our results show that the proposed scheme can achieve a gain that is two times greater than a non-cooperative scheme.
network coding, which works in the network layer, is an effective technology to improve the throughput of two-way relay networks. In this paper, we compare the existing network coding schemes: traditional network codi...
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ISBN:
(纸本)9781457720536
network coding, which works in the network layer, is an effective technology to improve the throughput of two-way relay networks. In this paper, we compare the existing network coding schemes: traditional network coding (NC) scheme, physical-layer network coding (PNC) scheme and soft network coding (SNC) scheme, and propose a new physical layer scheme which can be seen as the implementation of network coding in two-way relay networks. Relay nodes combine the received signals from two source nodes before demodulation and channel decoding. The computational complexity and BER performance of the proposed scheme are analyzed compared with the previous schemes. Theoretical analysis show that the proposed scheme can save 50% computational cost of demodulation and channel decoding processes compared with NC scheme, meanwhile increase the power efficiency of the relay nodes in two-way relay networks significantly. Future works with the proposed scheme are also discussed.
Recent works by Ahmad et al. and by Holl-mann studied the concept of "locally repairable regenerating codes (LRRCs)" that successfully combines the functional repair and partial information exchange of regen...
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Recent works by Ahmad et al. and by Holl-mann studied the concept of "locally repairable regenerating codes (LRRCs)" that successfully combines the functional repair and partial information exchange of regenerating codes (RCs) with the much-desired local repairability feature of locally repairable codes (LRCs). One important issue that needs to be addressed by any local repair schemes (including both LRCs and LRRCs) is that sometimes designated helper nodes may be temporarily unavailable, the result of various reasons that include multiple failures, degraded reads, or power-saving strategies to name a few. Under the setting of LRRCs with temporary node unavailability, this paper studies the impact of different helper selection methods. It proves that with node unavailability, all existing methods of helper selection, including those used in RCs and LRCs, can be insufficient in terms of achieving the optimal repair-bandwidth. For some scenarios, it is necessary to combine LRRCs with a new class of helper selection methods, termed dynamic helper selection, to achieve optimal repair-bandwidth. This paper also compares the performance of different classes of helper selection methods and answers the following fundamental question: is one method of helper selection intrinsically better than the other? for various scenarios.
We study the role of caches in wireless interference networks. We focus on content caching and delivery across a Gaussian interference network, where both transmitters and receivers are equipped with caches. We provid...
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We study the role of caches in wireless interference networks. We focus on content caching and delivery across a Gaussian interference network, where both transmitters and receivers are equipped with caches. We provide a constantfactor approximation of the system's degrees of freedom (DoF), for arbitrary number of transmitters, number of receivers, content library size, receiver cache size, and transmitter cache size (as long as the transmitters combined can store the entire content library among them). We demonstrate approximate optimality with respect to information-theoretic bounds that do not impose any restrictions on the caching and delivery strategies. Our characterization reveals three key insights. First, the approximate DoF is achieved using a strategy that separates the physical and network layers. This separation architecture is thus approximately optimal. Second, we show that increasing transmitter cache memory beyond what is needed to exactly store the entire library between all transmitters does not provide more than a constant-factor benefit to the DoF. A consequence is that transmit zero-forcing is not needed for approximate optimality. Third, we derive an interesting tradeoff between the receiver memory and the number of transmitters needed for approximately maximal performance. In particular, if each receiver can store a constant fraction of the content library, then only a constant number of transmitters are needed. Our solution to the caching problem requires formulating and solving a new communication problem, the symmetric multiple multicast X-channel, for which we provide an exact DoF characterization.
In this paper, we investigate the lifetime optimization for wireless multihop networks with network coding. We formulate the problems for three different cases with (i) no network coding, (ii) two-way network coding, ...
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ISBN:
(纸本)9781467358293;9781467358309
In this paper, we investigate the lifetime optimization for wireless multihop networks with network coding. We formulate the problems for three different cases with (i) no network coding, (ii) two-way network coding, and (iii) overhearing network coding. These problems are solved using interior-point method and the lifetime in all these cases are evaluated in random topologies with respect to power control models, the number of flows, traffic demand distributions and initial energy of each node. Numerical results show following observations: (1) With weak power control, network coding can achieve better lifetime gain;(2) Both lifetime gain and computation overhead of network coding increase with the number of flows;(3) The impact of traffic demand distributions and initial energy on the lifetime performance is negligible;(4) The overhearing network coding, although having higher computation overhead, does not perform significantly better than much simpler two-way network coding.
Considering a multicast scenario, we want to minimize the resources used for network coding while achieving the desired throughput. We demonstrate a standard genetic algorithm (GA) approach to the solution of this NP-...
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ISBN:
(纸本)9781467322010
Considering a multicast scenario, we want to minimize the resources used for network coding while achieving the desired throughput. We demonstrate a standard genetic algorithm (GA) approach to the solution of this NP-hard problem. Features of standard GA are shown through simulations, based on which we propose our improved GA approach. By enlarging initial population, adopting dynamic mutation and crossover rate and improving the evaluation of fitness value, our improved GA's performance is priory to the standard GA, which is testified through simulations on networks randomly generated.
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