In local loss recovery schemes, a small number of recovery nodes distributed along the transmission paths save incoming packets temporarily in accordance with a specified cache policy and retransmit these packets if t...
详细信息
In local loss recovery schemes, a small number of recovery nodes distributed along the transmission paths save incoming packets temporarily in accordance with a specified cache policy and retransmit these packets if they subsequently receive a request message from a downstream receiver. To reduce the recovery latency, the cache policy should ensure that the recovery nodes are always able to satisfy the retransmission requests of the downstream receivers. However, owing to the limited cache size of the recovery nodes and the behavior of the cache policy, this cannot always be achieved, and thus some of the packets must be retransmitted by the sender. Accordingly, this paper develops a new network-coding-based cache policy, designated as network-coding-based FIFO (NCFIFO), which extends the caching time of the packets at the recovery nodes without dropping any of the incoming packets. As a result, the lost packets can be always recovered from the nearest recovery nodes and the recovery latency is significantly reduced. The loss recovery performance of the NCFIFO cache policy is compared with that of existing cache policies by performing a series of simulation experiments using both a uniform error model and a burst error model. The simulation results show that the NCFIFO cache policy not only achieves a better recovery performance than existing cache policies, but also provides a more effective solution for managing a small amount of cache size in environments characterized by a high packet arrival rate. Copyright (c) 2011 John Wiley & Sons, Ltd.
Batched sparse (BATS) code is a class of temporal network code that achieves near-optimal tradeoff between network throughput and coding length for multi-hop erasure networks. However, the performance of the tradition...
详细信息
Batched sparse (BATS) code is a class of temporal network code that achieves near-optimal tradeoff between network throughput and coding length for multi-hop erasure networks. However, the performance of the traditional BATS code degrades dramatically when the designed degree distribution does not match the actual channel condition. In this paper, we first prove that a universal degree distribution that asymptotically achieves the optimal rate for all channel rank distributions does not exist for BATS code with batch size greater than one. We then propose a quasi-universal BATS (QU-BATS) code that achieves near-optimal performance for a range of channel conditions. This makes it suitable for use in scenarios where the end-to-end channel rank distribution is not fixed or not exactly known, e.g., in multicast or wireless transmission. In the proposed QU-BATS coding scheme, multiple degree distributions are designed, and the coded packets are generated according to different degree distributions at different transmission stages. Simulation results show that the proposed QU-BATS code strictly outperforms the fountain code and the traditional BATS codes for multihop data streaming over uncertain or time-varying network links, with lower decoding complexity.
In the wireless communication system, interference is considered harmful. Wireless networks strive to avoid scheduling multiple transmissions at the same time in order to prevent interference. While Physical layer Net...
详细信息
In the wireless communication system, interference is considered harmful. Wireless networks strive to avoid scheduling multiple transmissions at the same time in order to prevent interference. While Physical layer network coding (PNC) was proposed to embrace interference in order to improve throughput performance. During the second stage of PNC, the intermediate node broadcast the mapping signal to all of destinations, and PNC uses the TDM in order to avoid the interference from same frequency. As a result, when the user receives the mapping signal from the relay station, we could not send the second frame. In this paper, an improved scheme based on PNC is proposed in Two-way system. The paper adopts the Paired Communication Multiple Access (PCMA) idea to handle the mixed signal in the same slot, and implements the scheme that the sender could send the frames continuously. Extensive simulation studies show that the new Continuous PNC scheme is feasible and improves the communication throughput effectively by 60%.
The universal strongly secure network coding scheme allows communication at maximum rate while ensuring that, independently from the underlying network code, no part of the secret message is revealed to the wiretapper...
详细信息
ISBN:
(纸本)9781467325790
The universal strongly secure network coding scheme allows communication at maximum rate while ensuring that, independently from the underlying network code, no part of the secret message is revealed to the wiretapper. Although Silva and Kschischang showed the existence of such a scheme, the explicit construction remained an open question. This paper demonstrates an explicit construction of the scheme that uses secret sharing schemes based on maximum rank distance (MRD) codes, which can be viewed as a special case of Ozarow-Wyner coset coding scheme.
In this paper, we consider the energy efficiency as a metric to evaluate the performance of the network coding technique when applied to a feedback-assisted multiple access cooperative network, where multiple nodes ha...
详细信息
In this paper, we consider the energy efficiency as a metric to evaluate the performance of the network coding technique when applied to a feedback-assisted multiple access cooperative network, where multiple nodes have independent information to transmit to a common destination. The energy consumption of the transmission and reception circuits is taken into account, and it is shown that only one bit of feedback may reduce the network consumption when compared schemes without feedback. The optimal number of nodes that minimizes the energy consumption of the network as a function of the distance is obtained analytically, and confirmed by numerical results.
We investigate a novel coded modulation scheme for physical layer network coding (PLNC) in the two-way relay (TWR) fading channel. Using an adaptive soft demodulator and independent decoding levels, the proposed schem...
详细信息
We investigate a novel coded modulation scheme for physical layer network coding (PLNC) in the two-way relay (TWR) fading channel. Using an adaptive soft demodulator and independent decoding levels, the proposed scheme can eliminate the effect of fading on the TWR channel. To reduce system complexity at the relay, we also give a low-complexity two-demodulator scheme. Based on maximizing the mutual information between received signal and network coded symbol, the adaptive selection of the two demodulators is then optimized. The proposed simplified scheme exhibits advantages in terms of flexibility, complexity and performance.
In this paper, we present a novel Cluster-based Separate networking coding (CSNC) scheme, as a solution to solve the problem of continuous data collection for WSNs with a mobile BS. By separately encoding a certain nu...
详细信息
In this paper, we present a novel Cluster-based Separate networking coding (CSNC) scheme, as a solution to solve the problem of continuous data collection for WSNs with a mobile BS. By separately encoding a certain number of data segments in a combined data segment and doing decoding-free data replacement, CSNC not only provides efficient storage method for continuous data, but also maintains a high success ratio of data collection. The comprehensive performance evaluation has been conducted through computer simulation. It is shown that CSNC outperforms the existing PNC scheme significantly.
For MIMO two-way relay channel, this paper proposes a novel scheme, VBLAST-PNC, to transform the two superimposed packets received by the relay to their network coding form. Different from traditional schemes, which t...
详细信息
ISBN:
(纸本)9781467358309
For MIMO two-way relay channel, this paper proposes a novel scheme, VBLAST-PNC, to transform the two superimposed packets received by the relay to their network coding form. Different from traditional schemes, which tries to detect each packet before network coding them, VBLAST-PNC detects the summation of the two packets before network coding. In particular, after firstly detecting the second layer signal in 2-by-2 MIMO system with VBLAST, we only cancel part of the detected signal, rather than canceling all the components, from the first layer. Then we directly map the obtained signal, which is a weighted summation of the first layer and the second layer, to the network coding form. With such partial interference cancellation, the error propagation effect is significantly mitigated and the performance is thus improved as shown in simulations.
We consider a two-user state-dependent multiaccess channel in which the states of the channel are known non-causally to one of the encoders and only strictly causally to the other encoder. Both encoders transmit a com...
详细信息
ISBN:
(纸本)9781467325790
We consider a two-user state-dependent multiaccess channel in which the states of the channel are known non-causally to one of the encoders and only strictly causally to the other encoder. Both encoders transmit a common message and, in addition, the encoder that knows the states non-causally transmits an individual message. We find explicit characterizations of the capacity region of this communication model. The analysis also reveals optimal ways of exploiting the knowledge of the state only strictly causally at the encoder that sends only the common message when such a knowledge is beneficial. The encoders collaborate to convey to the decoder a lossy version of the state, in addition to transmitting the information messages through a generalized Gel'fand-Pinsker binning. Particularly important in this problem are the questions of 1) optimal ways of performing the state compression and 2) whether or not the compression indices should be decoded uniquely. We show that both compression à-la noisy network coding, i.e., with no binning, and compression using Wyner-Ziv binning are optimal. The scheme that uses Wyner-Ziv binning shares elements with Cover and El Gamal original compress-and-forward, but differs from it mainly in that backward decoding is employed instead of forward decoding and the compression indices are not decoded uniquely. Finally, by exploring the properties of our outer bound, we show that, although not required in general, the compression indices can in fact be decoded uniquely essentially without altering the capacity region, but at the expense of larger alphabets sizes for the auxiliary random variables.
In this paper,we construct a practical asymmetrical bi-directional multi-relay system model with considering the effect of distance between source nodes and destination *** two outage probability expressions of the sy...
详细信息
ISBN:
(纸本)9781467321006
In this paper,we construct a practical asymmetrical bi-directional multi-relay system model with considering the effect of distance between source nodes and destination *** two outage probability expressions of the system based on network coding and physical-layer network coding with decode- and-forward are *** analysis is proved correct by Monte Carlo *** we analyze the system average outage probability with different situations of power allocation coefficient,locations of the relay nodes,SNR and the number of relay nodes,indicating the inherent relationship between power allocation coefficient and total system power as well as the number of relay *** results indicate that the optimal power allocation coefficient of the system based on network coding and physical-layer network coding varies with respect to the distance between source nodes and destination nodes,and the outage probability of physical-layer network coding outperforms network coding ***,simulation results show that the system outage probability performance improves with the number of relay nodes increasing.
暂无评论