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Cell Wilting and Blossoming for Energy Efficiency
Get PDFIn this article, we consider the adoption of sleep modes for the base stations of a cellular access network, focusing on the design of base station sleep and wake-up transients.. We discuss the main issues arising with this approach, and we focus on the design of base station sleep and wake-up transients, also known as cell wilting and blossoming. The performance of the proposed procedures is evaluated in a realistic test scenario, and the results show that sleep and
wake-up transients are short, lasting at most 30 seconds.TRUEpu
P2P vs. IP multicast: Comparing approaches to IPTV streaming based on TV channel popularity
Get PDFAlready a popular application in the Internet, IPTV is becoming, among the service providers, a preferred alternative to conventional broadcasting technologies. Since many of the existing deployments have been done within the safe harbor of telco-owned networks, IP multicast has been the desired streaming solution. However, previous studies showed that the popularity of the TV channels follows the Pareto principle, with the bulk of TV channels being watched only by a small fraction of viewers. Recognizing the potential scalability issues, we believe that multicast streaming approach may not be desirable for unpopular TV channels, especially when there are many such channels in the provider’s service package. For this reason, the peer-to-peer content distribution paradigm is seen as an alternative, in particular for non-popular content. In order to analyze its viability, in this paper we perform a comparative analysis between IP multicast and a
peer-to-peer overlay using unicast connections as streaming approaches, in the context of channels with different degrees
of popularity. The analysis targets the bandwidth utilization, video quality and scalability issues, and our findings show that while multicast is always more efficient, peer-to-peer has a comparable performance for unpopular channels with a low number of viewers.TRUEpu
On the Fair Coexistence of Loss- and Delay-Based TCP
Get PDFThis paper presents and develops a novel delay-based
additive increase, multiplicative decrease (AIMD) congestion control algorithm. The main features of the proposed solution include: 1) low standing queues and delay in homogeneous environments (with delay-based flows only); 2) fair coexistence of delay- and lossbased flows in heterogeneous environments; 3) delay-based flows behave as loss-based flows when loss-based flows are present in the network; otherwise they revert to delay-based operation. It
is also shown that these properties can be achieved without any appreciable increase in network loss rate over that which would be present in a comparable network of standard TCP flows (lossbased AIMD). To demonstrate the potential of the presented algorithm, both analytical and simulation results are provided in a range of different network scenarios. These include stability and convergence results in general multiple-bottleneck networks and a number of simulation scenarios to demonstrate the utility of the
proposed scheme. In particular, we show that networks employing our algorithm have the features of networks in which RED AQM’s are deployed. Furthermore, in a wide range of situations (including high-speed scenarios), we show that low delay is achieved irrespective of the queueing algorithm employed in the network, with only sender-side modification to the basic AIMD algorithm.TRUEpu
Seamless internet 3G and opportunistic WLAN vehicular connectivity
Get PDFMost of the cellular network operators are nowadays striving to solve the problem caused by the increasing demand of mobile data users. In the near future, vehicles will be equipped not only with cellular connectivity, but also with dedicated short-range wireless devices, used to connect via single or multiple hops to fixed road side units attached to the infrastructure network to gain Internet access. Taking this hybrid-connectivity scenario, we propose Seamless Internet 3G and Opportunistic WLAN Vehicular Internet Connectivity (SILVIO), a solution for providing Internet connectivity in multi-hop vehicular ad hoc networks. Vehicles use the cellular network to assure always-on connectivity, while they opportunistically select to offload some non-critical flows to the multi-hop wireless local area network (WLAN). The advantages of this approach are twofold: the users can benefit from a higher bandwidth, while the operators can alleviate their overloaded cellular networks. SILVIO makes use of existing standard mobility mechanisms integrated, enhanced and extended to provide a seamless connectivity experience without introducing much complexity nor signalling overhead. One of the main contributions of this article is the proposal and analysis of different handover strategies between 3G and multi-hop WLAN networks for the vehicular scenario. A trace-driven simulator was developed to evaluate the performance improvements provided by SILVIO. Real traffic traces from the city of Madrid were used to feed the simulator which considers large vehicles as obstacles, as well. The obtained results show that using SILVIO the cellular network can be offloaded by a factor up to 80%.TRUEpu
Flexibility on Channel Access Allocations
No full textIMDEA Networks researchers have been contributing actively and extensively to this body of work over the last years. This contribution was produced in the following context:
Vice-chairing IEEE 802.21 TGb
Antonio de la Oliva was elected as IEEE 802.21 TGb Vice-chair in July 2011. The main responsibility of the position resides in shepherding the IEEE 802.21b specification until it is finally approved by the IEEE 802 Executive Committee. The specification, which contains significant contributions from on-going (MEDIEVAL) and past (CARMEN) European projects, passed the Sponsor Ballot in November 2011 and is currently awaiting approval-which will hopefully be ratified on the March 2012 plenary meeting.
Leading of the IEEE 802.21 Future Project Planning Ad-hoc group
The IEEE 802.21a and IEEE 802.21b amendments are already completed and waiting for ratification from IEEE 802 EC. This opens the door to new projects within the IEEE 802.21. IMDEA Networks, through one of its collaborators, is currently leading the Ad- Hoc group in charge of defining the new working items. Even more, some of the ideas developed within MEDIEVAL have been proposed and accepted as working items. A new Project Authorization Request (on MIHF_ID Group Management) was prepared through the last months of 2011, and submitted for approval on January 2012. The new project, to be named IEEE 802.21 TGd, will hopefully be approved on the March 2012 meeting.
Contributions to IEEE 802.21a/b/c and IEEE 802.11
Apart from the above activities, several technical contributions to IEEE 802.21a/b/c and IEEE 802.11 were performed during the 2011 period. In IEEE 802.21a several contributions and comments to address the different letters and sponsor ballots were performed. The main technical contributions from MEDIEVAL and CARMEN were introduced in IEEE 802.21b during 2010 and beginning of 2011 (2011 being devoted to defending such contributions during the different ballots). IEEE 802.21c standardizes the mechanisms to enable optimized single radio handover. Some of the technical details of this approach are very similar to the issues analyzed for DMM, hence the solutions designed within MEDIEVAL have been contributed to the task group. Finally, part of the work performed in FLAVIA was presented at the Next Wireless Generation Steering Committee (NWG SC), and was received positively.IEEEpu
Insomnia in the Access or How to Curb Access Network Related Energy Consumption
Get PDFAccess networks include modems, home gateways, and DSL
Access Multiplexers (DSLAMs), and are responsible for 70-
80% of total network-based energy consumption. In this
paper, we take an in-depth look at the problem of greening
access networks, identify root problems, and propose practical solutions for their user- and ISP-parts. On the user side, the combination of continuous light traffic and lack of alternative paths condemns gateways to being powered most of the time despite having Sleep-on-Idle (SoI) capabilities. To address this, we introduce Broadband Hitch-Hiking (BH2), that takes advantage of the overlap of wireless networks to aggregate user traffic in as few gateways as possible. In current urban settings BH2 can power off 65-90% of gateways. Powering off gateways permits the remaining ones to synchronize at higher speeds due to reduced crosstalk from having fewer active lines. Our tests reveal speedup up to 25%. On the ISP side, we propose introducing simple inexpensive switches at the distribution frame for batching active lines to a subset of cards letting the remaining ones sleep. Overall, our results show an 80% energy savings margin in access networks. The combination of BH2 and switching gets close to this margin, saving 66% on average.TRUEpu
Applying Low Discrepancy Sequences for Node-ID Assignment in P2PSIP
Get PDF—The IETF P2PSIP Working Group is currently
designing a standard overlay protocol, named RELOAD, that
employs a centralized node identifier (node-id) assignment for security reasons. Given this scenario, we propose the utilization of a Low Discrepancy Sequence (LDS) for the assignment of nodeids in the P2PSIP architecture. We perform an analytical and simulation study considering a Chord DHT that demonstrates that using a LDS-based node-id assignment guarantees a fair distribution of the node’s zone of responsibility, even in high churn scenarios. Previous studies have shown that a fairer distribution of the zones of responsibility sizes leads to a fairer
distribution of the storage and routing load. Therefore we
conclude that the proposed LDS node-id assignment provides
these features without adding any extra overhead.TRUEpu
Procedimiento de generación de direcciones IPv4 [PROCEDURE OF IPV4 ADDRESS GENERATION]
No full textMethod for generating additional IPv4 addresses extended within an Internet IPv4 header by inserting an additional IPv4 address associated with a network device, by means of an insertion and extraction module, as a suffix within the identification field and/or as a fragment of the position of the IPv4 header to be carried over the Internet IP from a first network device to a second network device.
Application number (OEPM): P200930504 (24.07.2009) | Publication number (1) (OEPM): ES2332498 (A1) (05.02.2010) | Publication number (2) (OEPM): ES2332498 (B1) (02.02.2011) | Patent granted (OEPM): 21.01.2011 | Owners: IMDEA NetworksIMDEA Networkspu
Performance Evaluation of Beacon Congestion Control Algorithms for VANETs
Get PDFBeacon and event-driven warning messages are two important messages that are used by many Intelligent Transportation Systems (ITS) applications for improving road safety and traffic efficiency. Beacon messages are regularly broadcast by each vehicle to notify other vehicles of its presence and its status. Event-driven warning messages are emitted when a vehicle or the road infrastructure discerns a critical situation. When congestion occurs, it is necessary to reduce the beacon load to keep a certain amount of the available bandwidth for the event-driven messages because they carry time-critical information of high importance. This paper considers three beacon congestion control algorithms that control the beacon load below a certain threshold by adjusting the transmit rate and/or transmit power for the beacon messages. We perform a large set of simulations to evaluate these algorithms. Our simulation results reveal promising results for these algorithms.Beacon and event-driven warning messages are two important messages that are used by many Intelligent Transportation Systems (ITS) applications for improving road safety and traffic efficiency. Beacon messages are regularly broadcast by each vehicle to notify other vehicles of its presence and its status. Event-driven warning messages are emitted when a vehicle or the road infrastructure discerns a critical situation. When congestion occurs, it is necessary to reduce the beacon load to keep a certain amount of the available bandwidth for the event-driven messages because they carry time-critical information of high importance. This paper considers three beacon congestion control algorithms that control the beacon load below a certain threshold by adjusting the transmit rate and/or transmit power for the beacon messages. We perform a large set of simulations to evaluate these algorithms. Our simulation results reveal promising results for these algorithms.TRUEpu