Today's Local Area Networks Research Articles

Grouping-Based MAC Protocols for EV Charging Data Transmission in Smart Metering Network

The next-generation advanced metering infrastructure, with the aid of two-way smart meters, is expected to support advanced functions such as remote reading and control and demand response. In this paper, we thus focus on the design of a smart metering network (SMN) for a future scenario where data from residences/customer premises are dominated by electric vehicle charging traffic. Therefore, the well-suited multiple access control (MAC) protocol design for such event-driven data is an emerging research area. However, because the number of smart meters (communication nodes) involved in such a single SMN is much larger than those in today's local area networks, the traditional random access MAC protocol is unlikely to perform well. In order to solve this problem, we propose two grouping-based MAC protocols, namely, TDMA-DCF and group leader DCF-TDMA schemes, in this paper. These two schemes are directed at 802.11-type networks operating at frequencies below 1 GHz, which has been adopted by a new IEEE 802.11ah standardization task group. We also conduct the comprehensive throughput and delay analysis on these schemes for unsaturated traffic conditions and hidden node events. The numerical results show that these two grouping-based MAC protocols significantly outperform the traditional random access protocol DCF in a densely populated network with large coverage such as SMN.

Early Token Ring Work at MIT

Token ring local area networks (LANs) are now obsolete technologies, but early work on them at the Massachusetts Institute of Technology produced networks that have left their mark on today's LANs. Noel Chiappa tells the story of early work at the Laboratory for Computer Science (LCS) at MIT on token rings.

Performance Comparison of IP-Networked Storage

Dramatically increasing amounts of digital data are placing huge requirements on storage systems. IP-networked storage systems, such as the network file system (NFS)-based network-attached storage (NAS) systems and the iSCSI-storage area network (SAN) systems, have become increasingly common in today's local area network (LAN) environments. The emergence of new storage techniques, such as object-based storage (OBS) and content aware storage (CAS), significantly improves the functionality of storage devices to meet further needs for storage sub-systems. However, these may impact system performance. This paper compares the performance of NFS, iSCSI storage, object-based storage devices (OSDs), and CAS-based storage systems in an environment with no data sharing across host machines. A gigabit ethernet network is used as the storage network. Test results demonstrate that the performances of these systems are comparable with CAS being much better than the others for write operations. The performance bottlenecks in these systems are analyzed to provide insight into how future storage systems may be improved and possible optimization methods. The analysis shows how the I/O interfaces in these systems affect the application performance and that network-based storage systems require optimized I/O latency and reduced network and buffer processing in the servers.

Internal control in local area networks: An accountant's perspective

Control and security are, arguably, among the major weaknesses of today's local area networks (LANs). This article presents an accountant's views of selected issues related to six internal control categories: (1) transmission controls, (2) access controls, (3) file management, (4) encryption, (5) activity monitoring, and (6) applications controls. The discussion includes a detailed example of a popular, commercially available LAN.