In this paper we study genus-4 curves obtained as double covers of elliptic curves. Firstly we shall give explicit defining equations of such curves with explicit criterion for whether it is nonsingular, and show the irreducibility of the long polynomial determining whether the genus-4 curve is nonsingular or not, in any characteristic ≠ 2 , 3 . Secondly, as an application, we enumerate superspecial genus-4 double covers of elliptic curves in small characteristic.

The movement of digital transformation (DX) has reached to telecom carriers. Telecom carriers have long been trying to automate their operation, including assurance works, such as responding to fault alarms. Automating failure response is challenging since the work flows comprises complex flow containing many conditional branches, requiring judgement of skilled operator. Currently, only specific portions are automated, such as verifying construction work and executing specific commands. Therefore, we clarify the evidence accumulation and response process based on system-wide evidence, and propose a fully automated failure response system employing an augmented orchestrator that implements functions equivalent to human judgment. This paper proposes an enhanced orchestrator to automate the entire flow of failure response, such as fault alarm response, which is capable of handling alarms of commercial environment. This paper also describes the problems to automate entire flow of failure response and evaluates implemented proposing orchestrator. Evaluation results show that the aggregation of process succeeded to reduce approximately 82% the amount of in work flow description, and also the orchestrator is capable to handle large amount of alarms in bursts, such as in case of disaster.

In recent years, there are many work efficiency efforts in particular automation of business processes in various industry. The same trend applies to the network operations of telecommunication carriers; however, although automation of service fulfillment, such as developing network services, is progressing, automation of service assurance such as responding to network failure has not progressed. Currently, network maintenance personnel have independently developed tools for automation of network maintenance (such as troubleshooting) process partially and they are manually performing maintenance tasks by coordinating multiple groups of tools. However, in view of the future decrease in the working population, work efficiency must be further improved. Following this situation, this article focuses on further automation of network maintenance process, by developing technologies to orchestrate existing automation tools. In this paper, handling network failures among network maintenance work is targeted, the challenges and the requirements for expansion in the range of automation is discussed, after discussing current automation of network maintenance at telecom carriers in the real world. After that an implementation method that satisfies these requirements using our orchestrator and OSS products is proposed and evaluated. By defining a workflow of network maintenance that makes each process reusable, it becomes easy to create new workflow and update the one, and furthermore it was found that by reviewing how to code the workflow, it was possible to significantly improve processing performance.

As an issue for operating and managing virtual network in telecommunication carrier networks, “multi-slice management technology” have been reported, and implementing method of autonomous control loop (closed loop) for virtual network is one of the key topic of it. This article focuses on the reduction of unexpected failures in large scale network, which is one of the major issues in network maintenance and assurance operation. This article proposes a method and an implementation of autonomous control loop (closed loop) that combines Network-AI, NFV orchestrator, virtual network, and cloud technologies. The benefits of the proposed method and the results of the implementation evaluation, including feasibility evaluation result of scheduled maintenance are also explained and reported in this article.

Raptor codes are known as precoded rateless codes that achieve the capacity of BEC. However the maximum degree of Raptor codes needs to be unbounded to achieve the capacity. In this paper we prove that spatially-coupled precoded rateless codes achieve the capacity with bounded degree under BP decoding.

Raptor codes are rateless codes that achieve the capacity on the binary erasure channels. However the maximum degree of optimal output degree distribution is unbounded. This leads to a computational complexity problem both at encoders and decoders. Aref and Urbanke investigated the potential advantage of universal achieving-capacity property of proposed spatially-coupled (SC) low-density generator matrix (LDGM) codes. However the decoding error probability of SC-LDGM codes is bounded away from 0. In this paper, we investigate SC-LDGM codes concatenated with SC low-density parity-check codes. The proposed codes can be regarded as SC Hsu-Anastasopoulos rateless codes. We derive a lower bound of the asymptotic overhead from stability analysis for successful decoding by density evolution. The numerical calculation reveals that the lower bound is tight. We observe that with a sufficiently large number of information bits, the asymptotic overhead and the decoding error rate approach 0 with bounded maximum degree.