10226081
A MAC protocol to reduce sensor network energy consumption using a wakeup radio
For increasing the life of sensor networks, each node must conserve energy as much as possible. In this paper, we propose a protocol in which energy is conserved by amortizing the energy cost of communication over multiple packets. In addition, we allow sensors to control the amount of buffered packets since storage space is limited. To achieve this, a two-radio architecture is used which allows a sensor to "wakeup" a neighbor with a busy tone and send its packets for that destination. However, this process is expensive because all neighbors must awake and listen to the primary channel to determine who is the intended destination. Therefore, triggered wakeups on the primary channel are proposed to avoid using the more costly wakeup procedure. We present a protocol for efficiently determining how large the period for these wakeups should be such that energy consumption is reduced.
7955941
Leveraging Channel Diversity for Key Establishment in Wireless Sensor Networks
As the use of sensor networks increases, security in this domain becomes a very real concern. One fundamental aspect of providing confidentiality and authentication is key distribution. While public-key encryption has provided these properties historically, sensors are resource constrained and benefit from symmetric key approaches. In this work, we propose a novel protocol for symmetric key distribution that uses the multiple channels available on sensor hardware. This channel diversity, along with spatial diversity of device locations, allows neighboring sensors to establish secure link keys from plaintext keys that are broadcast by sensors in their neighborhood. In particular, we show that using even one extra channel during the initialization procedure significantly improves the security of key establishment. Via analysis and simulation, we show that our protocol performs well in terms of network connectivity and resilience to colluding malicious devices, when compared to previous work. We show that our protocol can achieve over 90% connectivity among neighboring sensors with link keys that are uncompromised even when 80% of the devices in the network are malicious and collude. Finally, we present a thorough discussion of the comparative advantages and disadvantages of our approach compared to previous techniques.
1363737
Power save mechanisms for multi-hop wireless networks
In this paper, we discuss power save mechanisms that allow hosts to go to sleep to conserve energy. When sleeping hosts need to receive packets from other hosts, these hosts must somehow wake up the sleeping hosts. The paper discusses a busy-tone mechanism for this purpose, and an approach to improve the mechanism by using multiple busy tones. We generalize this protocol to develop the notion of multi-level power save mechanisms, and present some examples to illustrate this notion.
1871640
Exploring the Energy-Latency Trade-Off for Broadcasts in Energy-Saving Sensor Networks
Networking protocols for multi-hop wireless sensor networks (WSNs) are required to simultaneously minimize resource usage as well as optimize performance metrics such as latency and reliability. This paper explores the energy-latency-reliability trade-off for broadcast in multi-hop WSNs, by presenting a new protocol called PBBF (probability-based broadcast forwarding). PBBF works at the MAC layer and can be integrated into any sleep scheduling protocol. For a given application-defined level of reliability for broadcasts, the energy required and latency obtained are found to be inversely related to each other. Our analysis and simulation study quantify this relationship at the reliability boundary, as well as performance numbers to be expected from a deployment. PBBF essentially offers a WSN application designer considerable flexibility in choice of desired operation points
14631873
Paradigm Regained: Abstraction Mechanisms for Access Control
Access control systems must be evaluated in part on how well they enable one to distribute the access rights needed for cooperation, while simultaneously limiting the propagation of rights which would create vulnerabilities. Analysis to date implicitly assumes access is controlled only by manipulating a system’s protection state – the arrangement of the access graph. Because of the limitations of this analysis, capability systems have been ”proven” unable to enforce some basic policies: revocation, confinement, and the *-properties (explained in the text).
46718511
Capability-Based Financial Instruments
Every novel cooperative arrangement of mutually suspicious parties interacting electronically -- every smart contract -- effectively requires a new cryptographic protocol. However, if every new contract requires new cryptographic protocol design, our dreams of cryptographically enabled electronic commerce would be unreachable. Cryptographic protocol design is too hard and expensive, given our unlimited need for new contracts.Just as the digital logic gate abstraction allows digital circuit designers to create large analog circuits without doing analog circuit design, we present cryptographic capabilities as an abstraction allowing a similar economy of engineering effort in creating smart contracts. We explain the E system, which embodies these principles, and show a covered-call-option as a smart contract written in a simple security formalism independent of cryptography, but automatically implemented as a cryptographic protocol coordinating five mutually suspicious parties.
2078197
Collaborative Agents for C2 Teamwork Simulation
Existing team training software often requires that trainees be organized as physical teams and the members of the same team be trained at the same time. To demonstrate that team training software can be made more flexible, this paper presents an approach to incorporating software agents into the distributed command-and-control (C2) simulation software DDD, which supports only human players. Based on the multi-agent architecture CAST, the software agents are designed as a team to perform C2 tasks in the DDD. By associating the agents with the same basic capabilities as the DDD provides its human users, we illustrate how to specify the teamwork knowledge for the agent team, and how to make agents efficiently reason about the dynamic, partially observable environment. Different methods of communication and coordination among agents are also briefly described.
35339559
Two new families of large compound graphs
A question of special interest in graph theory is the design of large graphs. Specifically, we want to find constructions of graphs with order as large as possible for a given degree and diameter D . Two generalizations of two large compound graphs are proposed in this article. Three particular cases of these families of graphs presented here allow us to improve the order for the entries (15, 7), (13, 10), and (15, 10) in the table of the largest known ( , D)-graphs. © 2006 Wiley Periodicals, Inc. NETWORKS, Vol. 47(3), 140–146 2006
44565534
On the sum number of wheels
A graph G=(V,E) is a sum graph if there exists a labelling of the vertices of G with distinct positive integers so that uv∈E if and only if the sum of the labels assigned to u and v is the label of a vertex of G. The sum number of a graph is the minimum number of isolated vertices that, together with the given graph, form a sum graph. Sum graph labellings of wheels have been examined previously by other investigators. The sum number of an n spoked wheel, σ(Wn),n⩾5, has been found to be n when n is odd and n2+2 when n is even; however the proofs of these results are incomplete. In this paper we provide a complete proof and affirm that these previous results are correct.