Shared Medium Network Research Articles

Content caching for shared medium networks under heterogeneous users’ behaviors

Content caching is a widely studied technique aimed to reduce the network load imposed by data transmission during peak time while ensuring users’ quality of experience. It has been shown that when there is a common link between caches and the server, delivering contents via the coded caching scheme can significantly improve performance over conventional caching. However, finding the optimal content placement is a challenge in the case of heterogeneous users’ behaviors. In this paper we consider heterogeneous number of demands and non-uniform content popularity distribution in the case of homogeneous and heterogeneous user-preferences. We propose a hybrid coded–uncoded caching scheme to trade-off between popularity and diversity. We derive explicit closed-form expressions of the server load for the proposed hybrid scheme and formulate the corresponding optimization problem. Results show that the proposed hybrid caching scheme can reduce the server load significantly and outperforms the baseline pure coded and pure uncoded schemes and previous works in the literature for both homogeneous and heterogeneous user preferences.

Swarm dynamics for enhanced energy aware clustering

Energy can be efficiently conserved in WSN through clustering of nodes. As in all shared-medium networks, medium access control (MAC) protocol enables the smooth functioning of the network. An important function of MAC is to prevent the bottle-neck between two nodes sending data simultaneously. Many MAC protocols have been developed for smooth functioning of WSN which includes Berkeley medium access control (BMAC) which utilises minimal power listening as well as a proper preamble for minimal power communication. The main challenge of BMAC is overhearing and power wasting in long preambles. The aim of this work is to cluster BMA protocol using heuristic methods based on river formation dynamics (RFD) and particle swarm optimisation (PSO). The suggested protocol's performance is evaluated for packet delivery ratio (PDR), end to end delay, hop as well as jitter. The outcome shows that the proposed river PSO cluster BMAC performs better than BMAC with flooding and BMAC with cluster-based routing when compared with static and varying node mobility.

Swarm dynamics for enhanced energy aware clustering

Energy can be efficiently conserved in WSN through clustering of nodes. As in all shared-medium networks, medium access control (MAC) protocol enables the smooth functioning of the network. An important function of MAC is to prevent the bottle-neck between two nodes sending data simultaneously. Many MAC protocols have been developed for smooth functioning of WSN which includes Berkeley medium access control (BMAC) which utilises minimal power listening as well as a proper preamble for minimal power communication. The main challenge of BMAC is overhearing and power wasting in long preambles. The aim of this work is to cluster BMA protocol using heuristic methods based on river formation dynamics (RFD) and particle swarm optimisation (PSO). The suggested protocol's performance is evaluated for packet delivery ratio (PDR), end to end delay, hop as well as jitter. The outcome shows that the proposed river PSO cluster BMAC performs better than BMAC with flooding and BMAC with cluster-based routing when compared with static and varying node mobility.

DAART: Delay-aware Adaptive Round Time MAC Protocol to Improve Throughput in Light-trail Networks

Light-trail (LT) has been proposed as an attractive solution for optical networks to support emerging services such as video-on-demand, pseudo-wires, data-centers, etc. Due to the fact that light-trail (LT) is a shared-medium network, the media access control (MAC) protocol is essential to be implemented in the whole network. In this paper, we propose a novel MAC protocol called DAART (Delay-aware Adaptive Round Time) to improve the throughput in LT network. DAART MAC adopts the delay-aware mechanism to calculate the actual token holding time for every transmission node. More specifically, the token holding time can be evaluated from queue delay, transmission delay and slot-synchronization delay. To estimate the throughput performance of DAART MAC protocol, we give three different patterns of traffic and compare the throughput between DAART MAC and ART MAC. Simulation results show that DAART has more stable throughput performance than ART, which in return enhances the throughput of LT networks.

Controller Aggregation for Distributed Discrete-Event Supervisors on a Shared-medium Network

In our previous work, a communication protocol for the reliable communication of discrete event supervisors that are implemented on physically distinct controller devices on a shared-medium network was developed. Here, the required data exchange is captured by communication models that are algorithmically computed from an underlying hierarchical and decentralized supervisor synthesis. These communication models are particularly efficient if all synthesized supervisors are implemented on distinct controller devices. In this paper, the general case is considered, where multiple supervisors can be aggregated on each controller device. To this end, the algorithmic communication model computation is adapted in order to remove communication among supervisors on the same controller device. The benefit of the controller aggregation is illustrated by a manufacturing system case study.

Multimedia-MAC protocol: its performance analysis and applications for WDM networks

The design of the medium-access control (MAC) protocol is the most crucial aspect for high-speed and high-performance local and metropolitan area networks, since the decisions made at this level determine the major functional characteristics of these networks. Most of the MAC protocols proposed in the literature are not suitable for multimedia applications, since they have been designed with one generic traffic type in mind. As a result, they perform quite well for the traffic types they have been designed for, but poorly for other traffic streams with different characteristics. In this paper, we propose an integrated MAC protocol called the Multimedia-MAC (M-MAC), which integrates different MAC protocols into a hybrid protocol in a shared-medium network to efficiently accommodate various types of multimedia traffic streams with different characteristics and quality-of-service demands, namely, a constant-bit-rate traffic, bursty traffic (say, variable-bit-rate traffic), and emergency messages (say, control messages). We have developed a mathematical framework for the analysis and performance evaluation of our M-MAC protocol, which involves a queueing system with vacation. We have applied our M-MAC design approach to a wavelength-division multiplexing network, and evaluated its performance under various traffic conditions.

SAILOR: a source assisted partial destination slot release scheme for slotted networks

In this paper, we present a new scheme that enables destination nodes in a slotted shared medium network to release some received slots, hence making them available for reuse by other downstream nodes in the network. This scheme ensures a significant increase in the effective capacity of the network without any noticeable degradation in node processing delays, or increase in node complexity. We also present a literature review of works on spatial and slot reuse.

Contents

Karaoke lets people sing along to recorded accompaniments. Many karaoke systems provide the accompaniment, on-screen vocal texts for the singer to follow, and a video that is appropriate to the selected song. There are currently three types of karaoke systems: those for karaoke houses, cable TV companies, and home use. These are all standalone systems that require considerable human interaction. None of them can provide Karaoke on demand. To provide KOD, Y.-J. Lee, D.H.C. Du, and W.-H. Ma (1996) have proposed Sesame (a scalable and extensible architecture for multimedia entertainment). They claim that Sesame is modular (system elements can be easily replaced), scalable, extensible, and cost effective. Although other researchers have devised KOD schemes, these schemes are also standalone systems, are limited by throughput, or only provide audio. Sesame system would have three basic components: the server system, the network, and the user workstations. The server system uses off the shelf products such as a Fast-Wide SCSI II channel to connect storage devices to servers. Servers, also using commodity products such as Intel Pentium or Motorola PowerPC chips, administer the data. A switch based network connects the server to the workstations. A switch based network can provide each user with a dedicated link and bandwidth at low latency, unlike a shared medium network such as a LAN. The workstation forwards user requests, decompresses the data, mixes the user's voice with the soundtrack, and controls the audio-video display. The system uses MPEG compression.