Showing papers by "Telcordia Technologies published in 2003"

Efficient flooding with passive clustering-an overhead-free selective forward mechanism for ad hoc/sensor networks

Abstract: High capacity real-time data communications in sensor networks usually require multihop routing and ad hoc routing protocols. Unfortunately, ad hoc routing protocols usually do not scale well and cannot handle dense situations efficiently. These two issues-scalability and density-are the major limitations when we apply ad hoc routing schemes to sensor networks. Passive clustering (PC) classifies ad hoc/sensor nodes into critical and noncritical nodes without any extra transmission. By 2-b piggybacking and monitoring user traffic (e.g., data polling requests from a sink), PC deploys the clustering structure "for free". Moreover, PC makes even the first flooding as efficient as all subsequent floodings (i.e., no initialization overhead). PC introduces many benefits, including efficient flooding and density adaptation. As a result, PC reduces control overhead of ad hoc routing protocols significantly and, as a consequence, enables ad hoc routing in large, dense sensor networks. The resulting structure can be utilized in cluster-based ad hoc network/sensor networking as well as for active node selection.

Public Key Encryption with keyword Search.

Abstract: We study the problem of searching on data that is encrypted using a public key system. Consider user Bob who sends email to user Alice encrypted under Alice’s public key. An email gateway wants to test whether the email contains the keyword “urgent” so that it could route the email accordingly. Alice, on the other hand does not wish to give the gateway the ability to decrypt all her messages. We define and construct a mechanism that enables Alice to provide a key to the gateway that enables the gateway to test whether the word “urgent” is a keyword in the email without learning anything else about the email. We refer to this mechanism as Public Key Encryption with keyword Search. As another example, consider a mail server that stores various messages publicly encrypted for Alice by others. Using our mechanism Alice can send the mail server a key that will enable the server to identify all messages containing some specific keyword, but learn nothing else. We define the concept of public key encryption with keyword search and give several constructions.

Voice performance in WLAN networks - an experimental study

Abstract: In this work, we measure wireless local area network (WLAN) voice performance and capacity. While most WLAN applications today are data centric, the growing popularity of Voice over IP (VoIP) applications and the escalating trend towards convergence with cellular networks will catalyze an increased mix of voice traffic. Since voice applications must compete with each other and with simultaneous data applications for WLAN bandwidth, quantifying voice performance and capacity in the presence of background data traffic is an important issue. We offer a practical investigation into the ability of 802.11b MAC layer to support simultaneous voice and data. We quantify VoIP capacity for standard WLAN networks, indicative of those already in the field, as well as evaluate the practical benefits of implementing backoff control and priority queuing at the access point. Conclusions are drawn based on an extensive set of real-world measurements conducted using off-the-shelf equipment in a commercial testbed.

Signature based intrusion detection for wireless ad-hoc networks: a comparative study of various routing protocols

Abstract: In this paper we focus on intrusion detection in wireless networks. The intrusion detection community has been concentrating mainly on wired networks. Techniques geared towards wireline networks would not suffice for an environment consisting of multihop wireless links because of the various differences such as lack of fixed infrastructure, mobility, the ease of listening to wireless transmissions, lack of clear separation between normal and abnormal behavior in ad hoc networks. In this paper we consider the signature detection technique and investigate the ability of various routing protocols to facilitate intrusion detection when the attack signatures are completely known. We show that reactive ad-hoc routing protocols suffer from a serious problem due to which it might be difficult to detect intrusions even in the absence of mobility. Mobility makes the problem of detecting intruders harder. We also investigate a relationship between the probability of detecting an intrusion and the number of nodes that must participate in the process of detecting intrusions.

Location prediction algorithms for mobile wireless systems

Abstract: Predicting the location of a mobile wireless user is an inherently interesting and challenging problem. Location prediction has received increasing interest over the past decade, driven by applications in location management, call admission control, smooth handoffs, and resource reservation for improved quality of service. It is likely that location prediction will receive even more interest in the future, especially given the increased availability and importance of location estimation hard-ware and applications.In this chapter, we present an overview of location prediction in mobile wireless systems. We do not attempt to provide a comprehensive survey of all techniques and applications, but offer instead a description of several types of algorithms used for location prediction. We classify them broadly into two types of approaches: (1) domain-independent algorithms that take results from Markov analysis or text compression algorithms and apply them to prediction, and (2) domain-specific algorithms that consider the geometry of user motion as well as the semantics of the symbols in the user's movement history. We briefly mention other algorithms using Bayesian or neural network approaches, and end with some concluding remarks.

Efficient flooding in ad hoc networks: a comparative performance study

Abstract: The blind flooding can become very inefficient because of redundant, "superfluous" forwarding. In fact, superfluous flooding increases link overhead and wireless medium congestion. In a large network, with heavy load, this extra overhead can have severe impact on performance and should be eliminated. Efficient flooding schemes to choose a dominant set of nodes have been recently proposed in ad hoc networks. In this paper, we compare the performance of a set of representative schemes via simulation using as criteria the flooding efficiency and the delivery ratio.

Round efficiency of multi-party computation with a dishonest majority

Abstract: We consider the round complexity of multi-party computation in the presence of a static adversary who controls a majority of the parties. Here, n players wish to securely compute some functionality and up to n - 1 of these players may be arbitrarily malicious. Previous protocols for this setting (when a broadcast channel is available) require O(n) rounds. We present two protocols with improved round complexity: The first assumes only the existence of trapdoor permutations and dense cryptosystems, and achieves round complexity O(log n) based on a proof scheduling technique of Chor and Rabin [13]; the second requires a stronger hardness assumption (along with the non-black-box techniques of Barak [2]) and achieves O(1) round complexity.

Dynamic telephone numbering system

Abstract: The present invention relates generally to logical telephone numbers. In particular, dynamic number users are able to obtain dynamic numbers and to map those numbers to routable numbers of their choosing. The present invention provides a tool for protecting privacy while sharing and/or publicizing a number for public purposes. The present invention relates to a Dynamic Telephone Number Service (DTNS.) wherein users are provided with a logical temporary telephone number that is mapped dynamically to a physically addressable number. The use of the DTNS allows a dynamic number user to publish the logical number, thus avoiding the need to publish private information and phone numbers for public purposes. Further, the logical number is not permanently assigned, but rather is temporary and provided to the dynamic number user for a relatively short period of time.

Experimental investigation of quantum key distribution through transparent optical switch elements

Abstract: Quantum key distribution (QKD) enables unconditional physical layer security for the distribution of cryptographic key material. However, most experimental demonstrations have relied on simple point-to-point optical links. In this paper we investigate the compatibility of QKD with reconfigurable optical networks. By performing the first tests of QKD transmission through optical switches, we study if there are impairment mechanisms other than switch insertion loss that impact the sifted and error corrected secret bit yield. Three types of transparent optical switch elements are investigated including lithium niobate (LiNbO/sub 3/), microelectromechanical systems (MEMS), and optomechanical. We show that QKD can be extended beyond point-to-point links to switched multinode architectures including protected ring networks to enhance quantum channel availability.

Quality of service (QoS) assurance system using data transmission control

Abstract: The present invention provides improved quality of service through data transmission rate control in a network. Data rate control may be in the downlink or uplink direction and may be statically or dynamically configured. Rate control may be implemented at varying points in the network including but not limited to at the wireless host, at the access point, at a separate device such as a server or at a separate location within the network. In one example of the present invention, a rate enforcement function is provided for identifying data packets to be enforced or identifying mapping between each packet and corresponding access point. Also, a rate decision function is also provided for determining the data rate to be enforced for each of the access points or each of the wireless hosts.

Network configuration management

Abstract: Customer premise network configuration to enable a new service within the network is provided by a network configuration manager (200 Figure 2). The network configuration manager is either manually or automatically invoked upon a new service being used in the network. The configuration manager obtains a service template (220) for the service, which template provides generic end-to-end requirements for enabling the service. A configuration generator generates vendor-neutral device-configuration settings from the service template. A service configuration validator module then validates the service (212). Finally, an adaptor (214) module translates the vendor-neutral device-configuration settings to vendor specific configuration settings corresponding to the devices in the network and configures the devices.

Interlayer fast authentication or re-authentication for network communication

Abstract: A system and method are provided for establishing a network communication session using fast authentication. In a network system a client or user device may establish a communication session with a server using full authentication. If the session is interrupted or discontinued and resumption of the session is requested, a session identifier of the previously established session may be compared to the session identifier of the requested session. If a match is detected, the session may be resumed using a fast authentication (or re-authentication) procedure such that the session is resumed more efficiently and expediently. Fast authentication may be performed, for example, even when the first session and the resumed second session are of different authentication layers, different types of network interfaces and/or different locations. Thus, a session, such as a TLS session, may resume functionality among multiple defined authentication protocols or technologies such as 802.1X, PANA or cellular based systems.

Dynamic routing on networks with fixed-size buffers

Abstract: The combination of the buffer size of routers deployed in the Internet and the Internet traffic itself leads routinely to routers dropping packets. Motivated by this, we initiate the rigorous study of dynamic store-and-forward routing on arbitrary networks in a model in which dropped packets must explicitly be taken into account. To avoid the uncertainties of traffic modeling, we consider arbitrary traffic on the network. We analyze and compare the effectiveness of several greedy, on-line, local-control protocols using a competitive analysis of the throughput. One goal of our approach is for the competitive results to continue to hold as a network grows without requiring the memory in the nodes to increase with the size of the network. Thus, in our model, we have link buffers of fixed size, B, which is independent of the size of the network, and B becomes a parameter of the model.Our results are in contrast to another adversarial traffic model known as Adversarial Queuing Theory (AQT), which studies the stability and growth rate of queues as a function of the network and traffic parameters. For example, in AQT the Furthest-To-Go (FTG) protocol is stable for all networks whereas Nearest-To-Go (NTG) can be unstable for some networks. Unlike AQT, in our setting NTG is preferable to FTG: we show that the NTG protocol is throughput-competitive on all networks whereas the FTG protocol has unbounded competitiveness whenever a network contains even small cycles.

Advanced DSL management

Abstract: Today's digital subscriber line deployments are often conservatively engineered to function in a statistically worst case environment. Crosstalk is treated as unknown and uncontrollable random noise, even though it is manmade. Other impairments are often treated by simply adding margin to crosstalk. While this simplistic practice currently suffices, it often provisions unnecessarily low bit rates. This article shows methods that can increase these bit rates and decrease DSL failure rates. Data can be collected about individual telephone lines and cables from loop databases, by automated test equipment, or from DSL modems. This data may then be fed into an advanced DSL management system with a database of DSL loop and noise characteristics, and an analysis engine that tailors DSL deployments to the actual individual line characteristics, to increase provisioned DSL bitrates while simultaneously increasing reliability and lowering maintenance costs. The maximum service can be provisioned with high accuracy, eliminating many service activation failures. Automated maintenance routines can even isolate faults before a customer experiences them. Dynamic spectrum management (DSM) treats crosstalk as the manmade noise it is, and jointly optimizes DSL transmit spectra and signals to minimize crosstalk and maximize received signals, allowing substantially higher DSL speeds than current practice. This opens the door for new services, including symmetric enterprise services and full video service, with minimal physical plant upgrade.

Method and system for real time cellular network configuration

Abstract: A method and system for automatically configuring the frequency allocation within a cellular system or network. The method requires the collection of measurements from different parts of a cellular network, generating statistics from these measurements, and combining these statistics with inventory, propagation and geographic data. The combined data is used as input to a frequency allocation algorithm. As a result, the allocation algorithm produces a frequency configuration set a quality measure of the configuration proposed and/or a set of recommendations that is fed back to the cellular base stations to re-allocate the frequency usage in a plurality of cells.

A multilayered mobility management scheme for auto-configured wireless IP networks

Abstract: The convergence of wireless and IP has led to the need for IP to handle mobility. The Mobile IP protocol was developed to facilitate IP mobility. However, it has a number of shortcomings for dynamically auto-configured networks. Mobility protocols like Mobile IP with Location Registers (MIP-LR) and Session Initiation Protocol (SIP) have been developed to address some of its shortcomings. Micromobility protocols like Cellular IP have been developed to address other shortcomings of Mobile IP. We present a new integrated mobility management scheme that advantageously combines the strengths of SIP and MIP-LR with the benefits of a micromobility management protocol similar to Cellular IP. A prototype implementation of our scheme is explained, and lessons learned in the prototyping process are presented.

Multicasting streaming media to mobile users

Abstract: Content distribution in general, and multicasting in particular, over a wired network to static hosts can be realized by placing proxies and gateways at several parts of the network. However, if the end hosts are mobile over heterogeneous wireless access networks, one needs to consider many operational issues such as network detection, handoff, join and leave latency, and desired level of quality of service, as well as caching and load balancing. This article surveys a set of protocols and technologies that offer multicast-based services for streaming multimedia in a mobile environment. It also brings forth some of the issues related to mobile content distribution in the wireless Internet that may be helpful during its deployment by application service providers.

Supporting real-time IP multimedia services in UMTS

Abstract: UMTS, the successor of GSM, is evolving toward a future wireless all-IP network. We explain how it will support real-time IP multimedia services, as these services are expected to drive the adoption of wireless all-IP networks. We not only focus on the centerpiece of IP multimedia support, the IP multimedia subsystem, but also include the GPRS transport capabilities and OSA middleware capabilities. This helps to explain how the IMS fits in with, and builds upon, other pieces of the UMTS network. We analyze the pros and cons of providing IP multimedia session control capabilities as opposed to just providing basic IP connectivity, and highlight selected features of the IMS design for discussion.

Improving Data Quality in Practice: A Case Study in the Italian Public Administration

Abstract: Assessing and improving the quality of data stored in information systems are both important and difficult tasks. For an increasing number of companies that rely on information as one of their most important assets, enforcing high data quality levels represents a strategic investment aimed at preserving the value of those assets. For a public administration or a government, good data quality translates into good service and good relationships with the citizens. Achieving high quality standards, however, is a major task because of the variety of ways that errors might be introduced in a system, and the difficulty of correcting them in a systematic way. Problems with data quality tend to fall into two categories. The first category is related to inconsistency among systems such as format, syntax and semantic inconsistencies. The second category is related to inconsistency with reality as it is exemplified by missing, obsolete and incorrect data values and outliers. In this paper, we describe a real-life case study on assessing and improving the quality of the data in the Italian Public Administration. The domain of study is set on taxpayer's data maintained by the Italian Ministry of Finances. In this context, we provide the Administration with a quantitative reckoning of such specific problems as record duplication and address mismatch and obsolescence, we suggest a set of guidelines for setting precise quality improvement goals, and we illustrate analysis techniques for achieving those goals. Our guidelines emphasize the importance of data flow analysis and of the definition of measurable quality indicators. The quality indicators that we propose are generic and can be used to describe a variety of data quality problems, thus representing a possible reference framework for practitioners. Finally, we investigate ways to partially automate the analysis of the causes for poor data quality.

Comparative study of various TCP versions over a wireless link with correlated losses

Abstract: In this paper, we investigate the behavior of the various Transmission Control Protocol (TCP) algorithms over wireless links with correlated packet losses. For such a scenario, we show that the performance of NewReno is worse than the performance of Tahoe in many situations and even OldTahoe in a few situations because of the inefficient fast recovery method of NewReno. We also show that random loss leads to significant throughput deterioration when either the product of the square of the bandwidth-delay ratio and the loss probability when in the good state exceeds one, or the product of the bandwidth-delay ratio and the packet success probability when in the bad state is less than two. The performance of Sack is always seen to be the best and the most robust, thereby arguing for the implementation of TCP Sack over the wireless channel. We also show that under certain conditions the performance depends not only on the bandwidth-delay product but also on the nature of timeout, coarse or fine. We have also investigated the effects of reducing the fast retransmit threshold.

A technique to generate feasible tests for communications systems with multiple timers

Abstract: We present a new model for testing real-time protocols with multiple timers, which captures complex timing dependencies by using simple linear expressions involving timer-related variables. This new modeling technique, combined with the algorithms to eliminate inconsistencies, allows generation of feasible test sequences without compromising their fault coverage. The model is specifically designed for testing to avoid performing full reachability analysis, and to control the growth of the number of test scenarios. Based on extended finite state machines, it is applicable to languages such as SDL, VHDL, and Estelle. The technique models a realistic testing framework in which each I/O exchange takes a certain time to realize and timers can be arbitrarily started or stopped. A software tool implementing this technique is used to generate test cases for the U.S. Army wireless standard MIL-STD 188-220.

Triggered playback of recorded messages to incoming telephone calls to a cellular phone

Abstract: The present invention provides system and method for delayed answering of a call to a cellular phone which can operate in either a distributed or a centralized manner. In particular, the system and method according to the present invention allows the cellular phone user upon receiving a call to play a message to the caller, such as informing the caller to “hold on” for a short time and that the user will be available shortly. The present invention provides a number of advantageous alternatives to provide a cellular phone user flexibility in answering incoming calls.

Scalable semantic brokering over dynamic heterogeneous data sources in InfoSleuth/spl trade/

Abstract: InfoSleuth is an agent-based system for information discovery and retrieval in a dynamic, open environment. Brokering in InfoSleuth is a matchmaking process, recommending agents that provide services to agents requesting services. This paper discusses InfoSleuth's distributed multibroker design and implementation. InfoSleuth's brokering function combines reasoning over both the syntax and semantics of agents in the domain. This means the broker must reason over explicitly advertised information about agent capabilities to determine which agent can best provide the requested services. Robustness and scalability issues dictate that brokering must be distributable across collaborating agents. Our multibroker design is a peer-to-peer system that requires brokers to advertise to and receive advertisements from other brokers. Brokers collaborate during matchmaking to give a collective response to requests initiated by nonbroker agents. This results in a robust, scalable brokering system.