987821
Using Clustering Information for Sensor Network Localization
Sensor network localization continues to be an important research challenge. The goal of localization is to assign geographic coordinates to each node in the sensor network. Localization schemes for sensor network systems should work with inexpensive off-the-shelf hardware, scale to large networks, and also achieve good accuracy in the presence of irregularities and obstacles in the deployment area. 
 
We present a novel approach for localization that can satisfy all of these desired properties. Recent developments in sensor network clustering algorithms have resulted in distributed algorithms that produce highly regular clusters. We propose to make use of this regularity to inform our localization algorithm. The main advantages of our approach are that our protocol requires only three randomly-placed nodes that know their geographic coordinates, and does not require any ranging or positioning equipment (i.e., no signal strength measurement, ultrasound ranging, or directional antennas are needed). So far, only the DV-Hop localization mechanism worked with the same assumptions [1]. We show that our proposed approach may outperform DV-Hop in certain scenarios, in particular when there exist large obstacles in the deployment field, or when the deployment area is free of obstacles but the number of anchors is limited.
1655475
On the distribution and revocation of cryptographic keys in sensor networks
Key management has two important aspects: key distribution, which describes how to disseminate secret information to the principals so that secure communications can be initiated, and key revocation, which describes how to remove secrets that may have been compromised. Key management in sensor networks face constraints of large scale, lack of a priori information about deployment topology, and limitations of sensor node hardware. While key distribution has been studied extensively in recent works, the problem of key and node revocation in sensor networks has received relatively little attention. Yet, revocation protocols that function correctly in the presence of active adversaries pretending to be legitimate protocol participants via compromised sensor nodes are essential. In their absence, an adversary could take control of the sensor network's operation by using compromised nodes which retain their network connectivity for extended periods of time. In this paper, we present an overview of key-distribution methods in sensor networks and their salient features to provide context for understanding key and node revocation. Then, we define basic properties that distributed sensor-node revocation protocols must satisfy and present a protocol for distributed node revocation that satisfies these properties under general assumptions and a standard attacker model.
5074364
Modeling adoptability of secure BGP protocols
Despite the existence of several secure BGP routing protocols, there has been little progress to date on actual adoption. Although feasibility for widespread adoption remains the greatest hurdle for BGP security, there has been little quantitative research into what properties contribute the most to the adoptability of a security scheme. In this paper, we provide a model for assessing the adoptability of a secure BGP routing protocol. We perform this evaluation by simulating incentives compatible adoption decisions of ISPs on the Internet under a variety of assumptions. Our results include: (a) the existence of a sharp threshold, where, if the cost of adoption is below the threshold, complete adoption takes place, while almost no adoption takes place above the threshold; (b) under a strong attacker model, adding a single hop of path authentication to origin authentication yields similar adoptability characteristics as a full path security scheme; (c) under a weaker attacker model, adding full path authentication (e.g., via S-BGP [9]) significantly improves the adoptability of BGP security over weaker path security schemes such as soBGP [16]. These results provide insight into the development of more adoptable secure BGP protocols and demonstrate the importance of studying adoptability of protocols.
6130133
Security and Privacy in Sensor Networks
Sensor networks offer economically viable solutions for a variety of applications. For example, current implementations monitor factory instrumentation, pollution levels, freeway traffic, and the structural integrity of buildings. Other applications include climate sensing and control in office buildings and home environmental sensing systems for temperature, light, moisture, and motion. Sensor networks are key to the creation of smart spaces, which embed information technology in everyday home and work environments. The miniature wireless sensor nodes, or motes, developed from low-cost off-the-shelf components at the University of California, Berkeley, as part of its smart dust projects, establish a self-organizing sensor network when dispersed into an environment. The privacy and security issues posed by sensor networks represent a rich field of research problems. Improving network hardware and software may address many of the issues, but others will require new supporting technologies.
8031191
Dynamic dictionary matching and compressed suffix trees
Recent breakthrough in compressed indexing data structures has reduced the space for indexing a text (or a collection of texts) of length <i>n</i> from <i>O</i>(<i>n</i> log <i>n</i>) bits to <i>O</i>(<i>n</i>) bits, while allowing very efficient pattern matching [10, 13]. Yet the compressed nature of such indices also makes them difficult to update dynamically. This paper presents the first <i>O</i>(<i>n</i>)-bit representation of a suffix tree for a dynamic collection of texts whose total length is <i>n</i>, which supports insertion and deletion of a text <i>T</i> in <i>O</i>(|<i>T</i> | log<sup>2</sup> <i>n</i>) time, as well as all suffix tree traversal operations, including forward and backward suffix links. This work can be regarded as a generalization of the compressed representation of static texts. Our new suffix tree representation serves as a core part in a compact solution for the dynamic dictionary matching problem, i.e., providing an <i>O</i>(<i>d</i>)-bit data structure for a dynamic collection of patterns of total length <i>d</i> that can support the dictionary matching query efficiently. When compared with the <i>O</i>(<i>d</i> log <i>d</i>)-bit suffix tree based solution of Amir <i>et al.</i>, the compact solution increases the query time by roughly a factor of log <i>d</i> only. In the study of the above results, we also derive the first <i>O</i>(<i>n</i>)-bit representation for maintaining <i>n</i> pairs of balanced parentheses in <i>O</i>(log <i>n</i>/log log <i>n</i>) time per operation, matching the time complexity of the previous <i>O</i>(<i>n</i> log <i>n</i>)-bit solution.
11373384
Joint Call Admission Control for Next Generation Wireless Network
Next generation wireless network (NGWN) will be heterogeneous in nature where different radio access technologies (RATs) such as UMTS, WiMax, WLAN, etc, coexist. This coexistence necessitates joint radio resource management (JRRM). This paper focuses on joint call admission control (JCAC) for NGWN. Factors that determine a user's preference for a particular RAT are discussed. We propose a JCAC algorithm which considers the user's preference in making admission decision. A specific case where the user prefers to be served by the RAT which has the least service cost is modeled and evaluated using Markov decision process. The results obtained shows that overall service cost in heterogeneous network can be significantly reduced by using the proposed joint call admission control
17538498
Reasoning about Bayesian Network Classifiers
Bayesian network classifiers are used in many fields, and one common class of classifiers are naive Bayes classifiers. In this paper, we introduce an approach for reasoning about Bayesian network classifiers in which we explicitly convert them into Ordered Decision Diagrams (ODDS), which are then used to reason about the properties of these classifiers. Specifically, we present an algorithm for converting any naive Bayes classifier into an ODD, and we show theoretically and experimentally that this algorithm can give us an ODD that is tractable in size cvcn given an intractable number of instances. Since ODDS are tractable representations of classifiers, our algorithm allows us to efficiently test the equivalence of two naive Bayes classifiers and characterize discrepancies between them. We also show a number of additional results including a count of distinct classifiers that can be induced by changing some CPT in a naive Bayes classifier, and the range of allowable changes to a CPT which keeps the current classifier unchanged.
3557483
Streaming encryption for a secure wavelength and time domain hopped optical network
We describe a working implementation of a streaming encryption system for optical networks. The 10 Gbps data stream is encrypted on the physical level in both the wavelength and time domains. Security is obtained by applying a strong pseudo-random hopping pattern to both. The AES algorithm in counter mode is used to control the switches that implement the hopping permutations. Because of the high throughput requirements, aggressive parallelizing and pipelining techniques are used to achieve data rates of 10 Gbps. The core logic of the system was implemented on the Virtex2-XC2V1000 FPGA. Using four FPGA boards and four serializer and deserializer chips, a secure switch of 4 users over 4 wavelengths can be realized, resulting in a total throughput of 10 Gbps. This system is important as a platform for further research in the area of secure optical networks.
8514683
Energy efficient online deadline scheduling
This paper extends the study of online algorithms for energy-efficient deadline scheduling to the overloaded setting. Specifically, we consider a processor that can vary its speed between 0 and a maximum speed T to minimize its energy usage (of which the rate is roughly a cubic function of the speed). As the speed is upper bounded, the system may be overloaded with jobs and no scheduling algorithms can meet the deadlines of all jobs. An optimal schedule is expected to maximize the throughput, and furthermore, its energy usage should be the smallest among all schedules that achieve the maximum throughput. In designing a scheduling algorithm, one has to face the dilemma of selecting more jobs and being conservative in energy usage. Even if we ignore energy usage, the best possible online algorithm is 4-competitive on throughput [12]. On the other hand, existing work on energy-efficient scheduling focuses on minimizing the energy to complete all jobs on a processor with unbounded speed, giving several O(1)-competitive algorithms with respect to the energy usage [2, 20]. This paper presents the first online algorithm for the more realistic setting where processor speed is bounded and the system may be overloaded; the algorithm is O(1)-competitive on both throughput and energy usage. If the maximum speed of the online scheduler is relaxed slightly to (1 + ε)T for some ε > 0, we can improve the competitive ratio on throughput to arbitrarily close to one, while maintaining O(1)-competitive on energy usage.