We provide a simple and improved security analysis of PMAC, a Parallelizable MAC (Message Authentication Code) defined over arbitrary messages. A similar kind of result was shown by Bellare, Pietrzak and Rogaway at Crypto 2005, where they have provided an improved bound for CBC (Cipher Block Chaining) MAC, which was introduced by Bellare, Killan and Rogaway at Crypto 1994. Our analysis idea is much more simpler to understand and is borrowed from the work by Nandi for proving Indistinguishability at Indocrypt 2005 and work by Bernstein. It shows that the advantage for any distinguishing attack for n-bit PMAC based on a random function is bounded by O(??q / 2^n), where ?? is the total number of blocks in all q queries made by the attacker. In the original paper by Black and Rogaway at Eurocrypt 2002 where PMAC was introduced, the bound is O(??^2 / 2^n). We also compute the collision probability of CBC MAC for suitably chosen messages. We show that the probability is ??( lq^2 / N) where l is the number of message blocks, N is the size of the domain and q is the total number of queries. For random oracles the probability is O(q^2 / N). This improved collision probability will help us to have an efficient distinguishing attack and MAC-forgery attack. We also show that the collision probability for PMAC is ??(q^2 / N) (strictly greater than the birthday bound). We have used a purely combinatorial approach to obtain this bound. Similar analysis can be made for other CBC MAC extensions like XCBC, TMAC and OMAC.

ITC/USA 2006 Conference Proceedings / The Forty-Second Annual International Telemetering Conference and Technical Exhibition / October 23-26, 2006 / Town and Country Resort & Convention Center, San Diego, California / As the integrated Network Enhanced Telemetry (iNET) program moves forward in resolving systems engineering design and architecture definition, critical technology “gaps” and a migration path to realizing the integration of this technology are needed to insure a smooth transition from the current legacy point to point telemetry links to a network oriented telemetry system. Specifically identified by the DoD aeronautical telemetry community is the need for a migration to a network solution for command, control, and transfer of test data by optimizing the physical, data link, and network layers. In this paper, we present a network centric telemetry preliminary architecture approach based on variants of 802.11 that leverages the open standards as well as the previous Advanced Range Telemetry (ARTM) work on the physical layer waveform. We present a burst modem approach based on the recent AOFDM 802.11a work, a TDMA-like MAC layer based on 802.11e, and then add additional MAC layer features to allow for the multi-hop aeronautical environment using a variant of the current working standard of 802.11s. The combined benefits of the variants obtained from 802.11a, 802.11e, and 802.11s address the needs for both spectrum efficiency in the aeronautical environment and the iNET program.

The purpose of this paper is to investigate Saunders MacLane's axioms for plane geometry. The wording of the axioms has been modified; however, the concept suggested by each axiom remains the same.

<p>To predict the lifetime of wireless sensor networks before their installation is an important concern. The IEEE 802.15.4 standard is specifically meant to support long battery life time; still there are some precautions to be taken by which a sensor network system application based on the standard can be made to run for longer time periods.</p><p>This thesis defines a holistic approach to the problem of energy consumption in sensor</p><p>networks and suggests a choice of node architecture, network structure and routing</p><p>algorithm to support energy saving in the network. The idea and thrust of the thesis is that stand-alone measures such as selecting a low-power microcontroller with embedded transceiver will not alone be sufficient to achieve energy saving over the entire network. A comprehensive design study with energy saving as a primary task must be made. Focus given on the design objectives needs to look at different aspects – application code, network configuration code, routing algorithms etc to come up with an energy efficient network.</p>

This work proposes a distributed dynamic channel assignment of multi-channel MAC protocol in Ad-Hoc networks. Major characteristics of the proposed protocol are: (a) each mobile node is equipped with two network interfaces, (b) no time synchronization is needed, (c) distribution channel assignment. The proposed protocol reduces the cost of channel negotiation by considering the property that a connection generates multiple frames for transmitting and can assign channel information faster. Compared with other multi-channel MAC protocols, the proposed algorithm allows the whole network channel allotment be stable quickly. The performance evaluation is conducted on NS-2. Simulation results show that the proposed protocol can reduce the cost of channel negotiation significantly, increase the network throughput.

We provide a simple and improved security analysis of PMAC, a Parallelizable MAC (Message Authentication Code) defined over arbitrary messages. A similar kind of result was shown by Bellare, Pietrzak and Rogaway at Crypto 2005, where they have provided an improved bound for CBC (Cipher Block Chaining) MAC, which was introduced by Bellare, Killan and Rogaway at Crypto 1994. Our analysis idea is much more simpler to understand and is borrowed from the work by Nandi for proving Indistinguishability at Indocrypt 2005 and work by Bernstein. It shows that the advantage for any distinguishing attack for n-bit PMAC based on a random function is bounded by O(σq / 2^n), where σ is the total number of blocks in all q queries made by the attacker. In the original paper by Black and Rogaway at Eurocrypt 2002 where PMAC was introduced, the bound is O(σ^2 / 2^n). We also compute the collision probability of CBC MAC for suitably chosen messages. We show that the probability is Ω( lq^2 / N) where l is the number of message blocks, N is the size of the domain and q is the total number of queries. For random oracles the probability is O(q^2 / N). This improved collision probability will help us to have an efficient distinguishing attack and MAC-forgery attack. We also show that the collision probability for PMAC is Ω(q^2 / N) (strictly greater than the birthday bound). We have used a purely combinatorial approach to obtain this bound. Similar analysis can be made for other CBC MAC extensions like XCBC, TMAC and OMAC.

Bluetooth is an emerging technology to build a solution for providing short range, low power, low cost, and ubiquitous wireless environments. In this paper we propose a algorithm for asynchronous data traffic at the Medium Access Control (MAC) layer to meet Bluetooth characteristic and compare with other scheduling algorithms. The algorithm, named Efficient Utilization Polling (EUP), uses a single bit of the payload packet header as supplied knowledge of queues of slaves to the master to dynamically adapt the polling intervals. We also propose a differentiation mechanism, named Shifting Polling Window (SPW), which is based on EUP and differentiates throughput between different classes and still keeps the link utilization almost the same.

To predict the lifetime of wireless sensor networks before their installation is an important concern. The IEEE 802.15.4 standard is specifically meant to support long battery life time; still there are some precautions to be taken by which a sensor network system application based on the standard can be made to run for longer time periods. This thesis defines a holistic approach to the problem of energy consumption in sensor networks and suggests a choice of node architecture, network structure and routing algorithm to support energy saving in the network. The idea and thrust of the thesis is that stand-alone measures such as selecting a low-power microcontroller with embedded transceiver will not alone be sufficient to achieve energy saving over the entire network. A comprehensive design study with energy saving as a primary task must be made. Focus given on the design objectives needs to look at different aspects – application code, network configuration code, routing algorithms etc to come up with an energy efficient network.

This thesis determines and compares the sparing effect of ketamine on the minimum alveolar concentration (MAC) of isoflurane in rabbits and dogs using two methods in a crossover random design. One method determined the MAC of isoflurane and ketamine combined after previous determination of the MAC of isoflurane during the same day. The second method determined the MAC for the combination without prior determination of the MAC of isoflurane. The concentration of ketamine and norketamine in plasma were also determined in dogs. For the first method, the MAC of isoflurane in rabbits was 2.15 ± 0.09% (mean ± SD) and decreased to 1.63 ± 0.07% during ketamine administration (1 mg/kg bolus and a constant rate infusion [CRI] of 40 µg/kg/min). In dogs, the same ketamine dose decreased the MAC of isoflurane from 1.18 ± 0.14% to 0.88 ± 0.14%. Re-determination of MAC of isoflurane performed after stopping the CRI yielded a MAC value of 2.04 ± 0.11% in rabbits and of 1.09 ± 0.16% in dogs. MAC values of the isoflurane and ketamine combination determined for the second method were 1.53 ± 0.22% in rabbits and 0.79 ± 0.11% in dogs. MAC values of isoflurane after stopping the CRI of ketamine were 1.94 ± 0.25% in rabbits and 1.10 ± 0.17% in dogs. The MAC value obtained in dogs for the isoflurane and ketamine combination with the first method was significantly higher with respect to the MAC value obtained with the second method (0.88 ± 0.14 versus 0.79 ± 0.11%); whereas in rabbits, MAC values were similar. During ketamine administration in dogs, plasma concentrations of ketamine at MAC values were similar for the first and second method (824 ± 195.7 ng/mL and 729 ± 133.4 ng/mL, respectively). After stopping the CRI, plasma concentrations during isoflurane MAC were also similar for the two methods (407 ± 176.2 ng/mL and 347 ± 81.2 ng/mL, respectively). MAC values for the isoflurane and ketamine combination obtained with both methods were statistically different in dogs but not in rabbits, however these findings may be the result of the design of the study and tolerable experimental error derived from MAC studies rather than true species differences.

How to improve the radio resource utilization and provide better quality-of-service (QoS) is an everlasting challenge to the designers of wireless networks. As an indispensable element of the solution to the above task, medium access control (MAC) protocols coordinate the stations and resolve the channel access contentions so that the scarce radio resources are shared fairly and efficiently among the participating users. With a given physical layer, a properly designed MAC protocol is the key to desired system performance, and directly affects the perceived QoS of end users. Distributed random access protocols are widely used MAC protocols in both infrastructure-based and infrastructureless wireless networks. To understand the characteristics of these protocols, there have been enormous efforts on their performance study by means of analytical modeling in the literature. However, the existing approaches are inflexible to adapt to different protocol variants and traffic situations, due to either many unrealistic assumptions or high complexity. In this thesis, we propose a simple and scalable generic performance analysis framework for a family of carrier sense multiple access with collision avoidance (CSMA/CA) based distributed MAC protocols, regardless of the detailed backoff and channel access policies, with more realistic and fewer assumptions. It provides a systematic approach to the performance study and comparison of diverse MAC protocols in various situations. Developed from the viewpoint of a tagged station, the proposed framework focuses on modeling the backoff and channel access behavior of an individual station. A set of fixed point equations is obtained based on a novel three-level renewal process concept, which leads to the fundamental MAC performance metric, average frame service time. With this result, the important network saturation throughput is then obtained straightforwardly. The above distinctive approach makes the proposed analytical framework unified for both saturated and unsaturated stations. The proposed framework is successfully applied to study and compare the performance of three representative distributed MAC protocols: the legacy p-persistent CSMA/CA protocol, the IEEE 802.15.4 contention access period MAC protocol, and the IEEE 802.11 distributed coordination function, in a network with homogeneous service. It is also extended naturally to study the effects of three prevalent mechanisms for prioritized channel access in a network with service differentiation. In particular, the novel concepts of ``virtual backoff event'' and ``pre-backoff waiting periods'' greatly simplify the analysis of the arbitration interframe space mechanism, which is the most challenging one among the three, as shown in the previous works reported in the literature. The comparison with comprehensive simulations shows that the proposed analytical framework provides accurate performance predictions in a broad range of stations. The results obtained provide many helpful insights into how to improve the performance of current protocols and design better new ones.