CTN Issue: January 2012

1. On Distributed Multimedia Scheduling with Constrained Control Channels

Traditional multimedia scheduling approaches assume perfect control channels where each node has access to the knowledge of its neighbors. However, in practice the control channels are always constrained and nodes can only exchange limited information with their neighbors, e.g., the control packets are lost during the wireless transmission, and the node only has partial network information. In this case, existing distributed multimedia scheduling schemes cannot work efficiently. This paper investigates how imperfect neighbor information affects the multimedia scheduling, and reveals the relationship between the control gain and scheduling performance based on available network and multimedia information. This paper demonstrates that the control gain can be chosen properly such that the optimal distributed multimedia scheduling can be achieved with an exponential convergence rate. In addition, an explicit equation for asymptotic convergence rate is derived for implementation, and some practical examples are provided to show how to achieve the convergence bound.

The results in this paper have some interesting implications on the practical use of multimedia communications, i.e., multimedia sensor network is a good example. As we know, current sensor networks due to their limit transmitting and sensing capacities can hardly ensure that the perfect control channel is available. Information-limited scheduling technique is a direction to provide a satisfying multimedia service in practical large scale networks, e.g., vehicular networks, internet of things etc. Therefore, the proposed multimedia scheduling scheme for multi-hop wireless networks is eager to have large application ground. Although the results of this paper are based on the synchronized nodes and noiseless control channel, these can be easily extended to any other practical scenarios, e.g., heterogeneous networks, using the similar analysis model.

Title and author(s) of the original paper in IEEE Xplore:
Title: On Distributed Multimedia Scheduling with Constrained Control Channels
Author: Liang Zhou, and Hsiao-Hwa Chen
This paper appears in: Multimedia, IEEE Transactions on
Issue Date: October 2011

2. Toward an Architecture for Monitoring Private Clouds

Cloud computing has emerged as a new model for service delivery. Also emerged are several issues, most of them related to adoption, security and management. Earlier adopters as well as potential users are faced with many management challenges and concerns, some of which concern business decisions, e.g., vendor lock-in while others are related to service operation, e.g. monitoring of network, storage, and computational resources. Despite the fact that the cloud abstracts complexity and technology details, some technological issues must be handled directly by the ones deploying and managing a cloud infrastructure. In private clouds, for instance, a common goal is to take advantage of the existing facilities. One common issue in such a case is having several different Linux distributions, which increases configuration and monitoring complexity. Cloud computing is a type of distributed computing, which means that cloud computing monitoring can benefit from tools and concepts already established in distributed computing management. The authors show that implementing and deploying monitoring solutions on installed infrastructures is viable, including the use of existing tools like:

• Nagios
• Xen
• Xen virtual machines
• Ethernet network
• System run levels and init.d scripts

They also mention that, even in private clouds, the heterogeneity of computing resources might require some extra effort when implementing the monitoring solution. In summary, the reader can find in this paper some important insights on how to orchestrate a monitoring solution using distributed computing resources and tools in general, as well as a generic cloud monitoring architecture for private clouds. The paper also cites the lack of open source, interoperable management and monitoring tools, denoting a promising development and business area.

Title and author(s) of the original paper in IEEE Xplore:
Title: Toward an Architecture for Monitoring Private Clouds
Author: De Chaves, S.A., Uriarte, R.B., and Westphall, C.B.
This paper appears in: Communications Magazine, IEEE
Issue Date: December 2011

3. Sub-Carrier-Multiplexed Duplex 64-QAM Radio-Over-Fiber Transmission for Distributed Antennas

The past years have witnessed a huge increase in the number of wireless subscribers accessing the Internet from mobile devices. The proportion of high-bandwidth services, such as video-on-demand, video conferencing, voice-over-IP and internet gaming is on the rise. A major contributor to the increase in the demand for these high-bandwidth services is the development of high bitrate portable devices, such as smart-phones and tablet PCs. These mobile devices use WiFi, 3G HSPA and imminently LTE technology for communication with wireless base stations or routers.

In line with the number of wireless subscribers, the number of base stations has to be increased in order to cope with the increased traffic and to provide improved coverage. As a result, the reduced distances between base stations have facilitated the employment of base station cooperation techniques that further improve received signal quality. However, this flawless tele-presence quality is achieved at the cost of having to exchange substantially more information amongst cooperating base stations. Radio-over-Fiber communication provides one of the most reliable, high-bandwidth and low-latency solutions for connecting base stations.

In this letter the authors demonstrate the feasibility of a cost-efficient optical link design for such a base station cooperation that relies on a minimum number of components whose parameters are close to those of commercially available components. With only a single laser source, and avoiding the use of high-frequency local oscillators at the base stations, full-duplex data transmission (240 Mbit/s in each direction) is accomplished to a pair of base stations located 5km and 10km from the central network unit, respectively.

Title and author(s) of the original paper in IEEE Xplore:
Title: Sub-Carrier-Multiplexed Duplex 64-QAM Radio-Over-Fiber Transmission for Distributed Antennas
Author: Salman Ghafoor and Lajos Hanzo
This paper appears in: Communications Letters, IEEE
Issue Date: December 2011

4. G.HNEM: The New ITU-T Standard on Narrowband PLC Technology

There is today a worldwide interest in the realization of the Smart Grid, and in particular of the communications part of it. Although the Smart Grid will be supported by a heterogeneous set of networking technologies, the use of Narrowband Power Line Communications (NB-PLC) which operate in the (3-500) kHz band provides several unique and fundamental benefits. Several bodies are engaged in the standardization of NB-PLC, including the IEEE and ITU. The ITU has approved the first next generation OFDM-based NB-PLC family of international standards in December 2011. This next generation family of standards finally arrives after a long monopoly of single-carrier NB-PLC technologies, offering much higher bit rates, robustness, and flexibility - which are vital for Smart Grid applications. Recommendations ITU-T G.9955 (Physical Layer) and G.9956 (Data Link Layer) define a family of three separate and self-contained NB-PLC standards:

G.hnem: a new NB-PLC technology developed by ITU-T in cooperation with members of the G3-PLC and PRIME Alliances;
G3-PLC: an established and field-proven NB-PLC technology contributed by members of the G3-PLC Alliance;
PRIME: an established and field-proven NB-PLC technology contributed by members of the PRIME Alliance

These three standards can be used for a variety of Smart Grid applications such as smart metering, distribution automation, electric car charging, demand response, etc. The availability of a family of standards is also important because power grids in different countries have different characteristics and may require a different communications network design. The paper focuses on the specifications of the new G.hnem standardwhich defines a NB-PLC OFDM-based technology that targets multiple Smart Grid applications and also in-home energy management and home automation, using IPv6 as the main networking protocol. G.hnem uses the latest advances in NB-PLC technology, including special means to improve sensitivity and robustness, multiple bandplans, adaptive medium access, simultaneous support of multiple network protocols, and state of the art security. The paper is part of a special issue on “Power line communications for automation networks and smart grid” that appeared in the IEEE Communications Magazine in December 2011.

Title and author(s) of the original paper in IEEE Xplore:
Title: G.HNEM: The New ITU-T Standard on Narrowband PLC Technology
Author: Vladimir Oksman (Lantiq); Jin Zhang (Marvell)
This paper appears in: Communications Magazine, IEEE
Issue Date: December 2011

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