In this paper we survey the various erasure codes which had been proposed and patented recently, and along the survey we provide introductory tutorial on many of the essential concepts and readings in erasure and Fountain codes. Packet erasure is a fundamental characteristic inherent in data storage and data transmission system. Traditionally replication/ retransmission based techniques had been employed to deal with packet erasures in such systems. While the Reed-Solomon (RS) erasure codes had been known for quite some time to improve system reliability and reduce data redundancy, the high decoding computation cost of RS codes has offset wider implementation of RS codes. However recent exponential growth in data traffic and demand for larger data storage capacity have simmered interest in erasure codes. Recent results have shown promising results to address the decoding computation complexity and redundancy tradeoff inherent in erasure codes.
Currently, the HTTP protocol supports a lot of different applications, with distinct traffic intensities and patterns. The ability to accurately map traffic flows to their corresponding application can be very useful in several operational and management tasks, like service differentiation and personalization, network resources optimization, network management and security. This paper discusses the possibility of performing the identification of HTTP-based applications in an efficient way, using a classification approach based on the multi-scale analysis of the traffic flows: by performing a wavelet decomposition, captured traffic can be fully characterized in terms of its time and frequency components, allowing the identification of differentiating characteristics/behaviours that can be used to discriminate between different applications. The results obtained by applying this methodology to traffic belonging to several Web-based applications show that it is able to achieve good classification results, while being immune to some of the most important drawbacks that limit the applicability of the most popular traffic identification approaches. Finally, the paper reviews the most relevant traffic classification methodologies that have been published so far, including some recent patents.
One of the key objectives of a smart grid is to provide reliable protection and control mechanisms in distribution networks. Pilot protection schemes being one of the most effective methods of protecting networked distribution lines, are extensively used in high voltage transmission grids. Pilot protection schemes use high-speed, interrelay communications for fast fault detection and isolation. The use of a broadband wireless access network such as IEEE802.16 based WiMAX can significantly extend the reach of a pilot protection scheme by providing a fast, reliable and pervasive communications alternative. However, significant challenges exist in terms of radio resource allocation to support such an event-driven, machine-to-machine (M2M) communication traffic over a WiMAX network which is traditionally optimized for various multimedia applications. As a solution, this paper proposes a novel radio resource scheduling service called Expedited Effort (EE) that uses a differentiated random access and a prioritized grant mechanism to transfer the time-critical pilot protection messages. Performance evaluation is conducted for both of the existing Best Effort (BE) and the proposed EE services under varying traffic load and channel conditions using a discrete-event simulation model based on OPNET. The simulation study reveals that while the existing BE service fails to meet the challenging QoS requirements of a pilot protection scheme, the proposed EE service provides satisfactory performance even under quite difficult channel conditions.
A novel cooperative scheme based on Physical layer Network Coding (PNC) for short range communication (SRC) networks is presented in this paper. We investigate a scenario of overlapping networks with multicast traffic and propose a technique for the leverage of inter-network cooperation. Our main goal is to exploit the characteristics of PNC in a solution for cooperative SRC networks, where energy efficiency is improved without degrading Quality of Service (QoS). The performance of our proposed cooperative scenario is highly energy efficient and it also presents high throughput. Comparing our scheme with a conventional protocol we show that it presents better performance. We analytically present the throughput, the delay and the energy efficiency of the neighbouring networks and we validate the mathematical analysis through extensive simulations. In addition, we provide an assessment of the impact of the capture effect on the proposed approach. Our proposal is inspired by recent patents in telecommunications that focus on interference cancellation.
This paper presents a fault-tolerant mutual exclusion dual-token algorithm named DTME in distributed system. The DTME algorithm is a kind of algorithm which is based on the token ring approach. It uses two tokens which can detect each other but have different function. With a new logical ring structure, the DTME algorithm uses a novel token passing strategy to arbitrate resources shared by multi-process simultaneously. The safety, liveness and robustness properties of the DTME algorithm have been proved in this paper. In addition, we design a corresponding recovery mechanism by analyzing the impact of node failures and loss of tokens. The evaluation shows that we obtained a better result on the fault-tolerant property, average message complexity and average waiting time of the algorithm by means of simulation, compared with Jayadev Misra’s algorithm and Hoda Taheri’s algorithm. Here we also discuss few patents that are relevant to the article.