An efficient QoS enhancement mechanism of VoIP using erasure array codes

In order to solve the problem of losing voice packets in voice over internet protocol(VoIP),a kind of lost packets double recovery algorithm is proposed. The algorithm is based on erasure coding technique which comes from highly available data storage systems. An efficient coding scheme with higher tolerance based on STAR and Reed-Solomon( RS) erasure code is described. An efficient method is also provided which could transform the voice data packets of one dimensional bit stream into two dimensional array according to given window size. If the lost rate has increased beyond the error correction capability,packet-loss concealment will be adopted. Under various conditions of packet-loss simulation during the experiments,the algorithm has proved its better performance on MOS rating and coding rate.

Cross-Rack Updates in Vertical Array Codes Storage Systems with High Fault Tolerance

Vertical array codes have less computational complexity and update complexity in comparison with horizontal array codes.However,the fault tolerance of the existing vertical array codes is in general lower than that of horizontal array codes.In addition,the cross-rack bandwidth is often the bottleneck of the update performance in erasure-coded storage systems.In this paper,we propose a cross-rack update(CRU)mechanism for vertical array codes intended to improve both the fault tolerance and update performance of erasure-coded storage systems.CRU builds on three parts:(i)stripe encoding,which can improve the fault tolerance of vertical code by encoding multiple sub-stripe;(ii)node grouping,which filters out the best combination of nodes to minimize cross-rack update traffic;(iii)selective logging,which can selectively log based on the location of data sub-blocks and parity sub-blocks to reduce disk I/O and cross-rack traffic.We evaluate CRU via trace-driven analysis and local cluster experiments.Evaluations show that CRU can significantly reduce cross-rack update traffic and improve system update throughput.

Analysis of Optical Signal Transmission Characteristics in AWG Multi/Demultiplexer with Electromagnetic Field Theory

Based on the electromagnetic field theory, the optical signal transmission characteristics in input/output waveguides, slab waveguides and arrayed waveguides of the arrayed waveguide grating (AWG) multi/demultiplexer are analyzed. The relationship between the physical parameters such as geometry sizes and relative refractive index in AWG multi/demultiplexer and the optical signal transmission characteristics are discussed. This theoretical study can be used for optimizing the design and improving the performance of the AWG multi/demultiplexer.

Ferroelectric Liquid Crystal Gates and Optical Computing

The surface stabilized ferroelectric liquid crystal device configuration and ferroelectric liquid crystal gates are described.The liquid crystal electrooptical gates have numerous applications,including optical computation,optodigital circuits,and optical communication networks.

Correction of CT Burst Array Errors in the Generalized-Lee-RT Spaces

In [Jain, S.： Array codes in the generalized-Lee-RT-pseudo-metric （the GLRTP-metric）, to appear in Algebra Colloq.], Jain introduced a new pseudo-metric on the space Matm×s（Zq）, the module space of all m × s matrices with entries from the finite ring Zq, generalized the classical Lee metric [Lee, C. Y.： Some properties of non-binary error correcting codes. IEEE Trans. Inform. Theory, IT-4, 77- 82 （1958）] and array RT-metric [Rosenbloom, M. Y., Tsfasman, M. A.： Codes for m-metric. Prob. Inf. Transm., 33, 45-52 （1997）] and named this pseudo-metric as the Generalized-Lee-RT-Pseudo-Metric （or the GLRTP-Metric）. In this paper, we obtain some lower bounds for two-dimensional array codes correcting CT burst array errors [Jain, S.： CT bursts from classical to array coding. Discrete Math., 308-309, 1489-1499 （2008）] with weight constraints under the GLRTP-metric.

Parametric array differential Pattern time delay shift coding underwater acoustic communication in the under-ice environment

In order to meet the demands of underwater acoustic communication in under ice environment,a differential Pattern time delay shift coding underwater acoustic communication method based on parametric array is introduced in this paper.The under ice underwater acoustic channel is characterized by heavy multipath transmission.Under this model,a parametric array emission method of Pattern signal is derived and the system performance is analyzed.A broadband low frequency sound waves with narrow beam-pattern,which will reduce the interface reflections and suppress the effects of multipath transmission,can be obtained by the emission method.The Songhua River under ice trial results show that there is an anti-multipath property and a higher data rate in the under-ice acoustic channel in proposed approach.

RDDP:An Efficient MDS Array Code on Toleration Triple Node Failures in Storage System

It is well known that erasure coding can be used in storage systems to efficiently store data while protecting against failures. Conventionally, the design of erasure codes has focused on the tradeoff between redundancy and reliability. Under this criterion, an maximum distance separable（MDS） code has optimal redundancy. In this paper, we address a new class of MDS array codes for tolerating triple node failures by extending the row di- agonal parity（RDP） code, named the RDDP（row double diagonal parity） code. The RDDP code takes advantages of good perform- ances of the RDP code with balanced I/0. A specific triple-erasure decoding algorithm to reduce decoding complexity is depicted by geometric graph, and it is easily implemented by software and hardware. The theoretical analysis shows that the comprehensive properties of the RDDP code are optimal, such as encoding and decoding efficiency, update efficiency and I/0 balance performance.