This thesis is a study on the issues involved in implementing asynchronous transfer mode (ATM) over satellite links and the ways in which ATM can be optimised to achieve better performance over such links. The main issue is the impact of errors introduced by the satellite links on the performance of ATM. Options to improve the performance of ATM over SATCOM have been identified and they are: (i) increase transmit power, (ii) FEC, (iii) adoption of an alternative ATM architecture, (iv) extensive to commercial-off-the-shelf (COTS) ATM equipments and (v) construction of ATM protocol enhancers. The fifth option which uses a combination of protocol conversions and error control techniques is preferred over the others as it allows maximum use of standard COTS ATM equipments and provides a framework for experimentation with multiple versions of ATM equipments (that are evolving rapidly). As part of the strategy of using protocol enhancement to improve the performance of ATM, two techniques have been proposed. The first technique is called cell header duplication, and it improves cell loss ratio by compressing the information in the cell headers and using the extra room in each header to carry the duplicate compressed header information of the previous cell. When a cell header is corrupted, the corrupted header information is replaced with the duplicate copy carried in the next cell, provided that too is not corrupted. This technique was compared with cell header interleaving and error tolerant addressing which are cell header protection techniques proposed by others. The second technique is called selective cell retransmission, which employs a partial retransmission (hybrid) ARO strategy to perform error recovery for only the individually errored non-realtime cells allowing it to achieve higher reliability of data transfer and more efficient utilisation of satellite bandwidth. The overhead in the proposed scheme varies according to the error conditions in the satellite channel making it an adaptive system. This is achieved by using a unique method of sending error erasure information (inserted into cells carrying negative acknowledgement messages) from the receiver to the transmitter which will use this information to pin-point the corrupted cells. The scheme is also compared with concatenated coding (using a Reed-Solomon code) and link protocols (using selective repeat (full retransmission) ARQ).

<p>Border Gateway Protocol (BGP) is a critical routing protocol of the internet, used to</p><p>exchange routing information between autonomous systems (ASes). BGP is highly</p><p>vulnerable to many attacks that can cause routing disturbance on the internet. This</p><p>paper describes BGP attacks, misconfigurations, causes of misconfigurations, impact</p><p>of these attacks and misconfigurations in BGP and counter measures. Also we</p><p>analyze new security architectures for BGP, comparison of these security protocols</p><p>and their deployment issues. At the end we propose new security solution that is</p><p>Defensive Routing Policy (DRP) to prevent BGP from malicious attacks and</p><p>misconfigurations. DRP is operationally deployable and very effective to solve BGP</p><p>problems.</p>

A wireless sensor network (WSN) is comprised of a few hundred or thousand au-tonomous sensor nodes spatially distributed over a particular region. Each sensornode is equipped with a wireless communication device, a small microprocessor, anda battery-powered energy source. Typically, the applications of WSNs such as habitatmonitoring, re detection, and military surveillance, require data collection, process-ing, and transmission among the sensor nodes. Due to their energy constraints andhostile environments, the main challenge in the research of WSN lies in prolongingthe lifetime of WSNs.In this dissertation, we present four dierent topology management protocols forK-coverage and load balancing to prolong the lifetime of WSNs.First, we present a Randomly Ordered Activation and Layering (ROAL) protocolfor K-coverage in a stationary WSN. The ROAL suggests a new model of layer cov-erage that can construct a K-covered WSN using the layer information received fromits previously activated nodes in the sensing distance. Second, we enhance the faulttolerance of layer coverage through a Circulation-ROAL (C-ROAL) protocol. Us-ing the layer number, the C-ROAL can activate each node in a round-robin fashionduring a predened period while conserving reconguration energy. Next, MobilityResilient Coverage Control (MRCC) is presented to assure K-coverage in the presence of mobility, in which a more practical and reliable model for K-coverage with nodalmobility is introduced. Finally, we present a Multiple-Connected Dominating Set(MCDS) protocol that can balance the network trac using an on-demand routingprotocol. The MCDS protocol constructs and manages multiple backbone networks,each of which is constructed with a connected dominating set (CDS) to ensure a con-nected backbone network. We describe each protocol, and compare the performanceof our protocols with Dynamic Source Routing (DSR) and/or existing K-coveragealgorithms through extensive simulations.The simulation results obtained by the ROAL protocol show that K-coverage canbe guaranteed with more than 95% coverage ratio, and signicantly extend networklifetime against a given WSN. We also observe that the C-ROAL protocol provides abetter reconguration method, which consumes only less than 1% of the recongura-tion energy in the ROAL protocol, with a greatly reduced packet latency. The MRCCprotocol, considering the mobility, achieves better coverage by 1.4% with 22% feweractive sensors than that of an existing coverage protocol for the mobility. The resultson the MCDS protocol show that the energy depletion ratio of nodes is decreasedconsequently, while the network throughput is improved by 35%.

In recent years, scientists have some inspiring breakthroughes in quantum algorithm. In 1994, Peter Shor published the Shor's Algorithm. He used the parallel property of quantum computing to do the quantum Fourier transform. In this way, quantum computer can both factor large integers and solve discrete logarithm problems in polynomial time. Shor's Algorithm proved that most of current used public key systems such as RSA and ElGamal will be solved with quantum computers in polynomial time. Therefore, scientists began to research on cryptography which is based on quantum physical qualities. In this paper, we designed two password authentication protocols. The security of the protocols is not based on classical computational complexity but on the principle of quantum mechanics. The first protocol uses additional quantum bits to prevent attackers. In this protocol, the transmitted bits are less than directly using BB84 protocol to generate a key and encode the password. The second protocol uses the property of quantum transmission. We used hash functions to increase the relationship between quantum bits, so the attackers can not get direct information from eavesdropped quantum bits. Our objective is to show that the security of the protocols is not based on the irreversibility of functions, but on the properties of quantum mechanics.

Warm-Mix Asphalt (WMA) refers to the asphalt concrete paving material produced and placed at temperatures approximately 50°F lower than those used for Hot-Mix Asphalt (HMA). Economic, environmental and engineering benefits have boosted the use of WMA technology across the world during the past decade. While WMA technology has been successfully utilized as a paving material, several specifications and mix design protocols remain under development. For example, currently, there is no consistent laboratory conditioning procedure for preparing WMA specimens for performance tests, despite being essential for mix performance. Based on previous studies, several candidate conditioning protocols for WMA Laboratory Mixed Laboratory Compacted (LMLC) and off-site Plant Mixed Laboratory Compacted (PMLC) specimens were selected, and their effects on mixture properties were evaluated. Mixture stiffness evaluated in a dry condition using the Resilient Modulus (MR) test (ASTM D-7369) was the main parameter used to select a conditioning protocol to simulate pavement stiffness in its early life. The number of Superpave Gyratory Compactor (SGC) gyrations to get 7±0.5% air voids (AV) was the alternative parameter. Extracted binder stiffness and aggregate orientation of field cores and on-site PMLC specimens were evaluated using the Dynamic Shear Rheometer (DSR) (AASHTO T315) and image analysis techniques, respectively. In addition, mixture stiffness in a wet condition was evaluated using the Hamburg Wheel-Track Test (HWTT) (AASHTO T324) stripping inflection point (SIP) and rutting depth at a certain number of passes. Several conclusions are made based on test results. LMLC specimens conditioned for 2 hours at 240°F (116°C) for WMA and 275°F (135°C) for HMA had similar stiffnesses as cores collected during the early life of field pavements. For off-site PMLC specimens, different conditioning protocols are recommended to simulate stiffnesses of on-site PMLC specimens: reheat to 240°F (116°C) for WMA with additives and reheat to 275°F (135°C) for HMA and foamed WMA. Additionally, binder stiffness, aggregate orientation, and overall AV had significant effects on mixture stiffness. Mixture stiffness results for PMFC cores and on-site PMLC specimens in a wet condition as indicated by HWTT agree with those in a dry condition in MR testing.

Border Gateway Protocol (BGP) is a critical routing protocol of the internet, used to exchange routing information between autonomous systems (ASes). BGP is highly vulnerable to many attacks that can cause routing disturbance on the internet. This paper describes BGP attacks, misconfigurations, causes of misconfigurations, impact of these attacks and misconfigurations in BGP and counter measures. Also we analyze new security architectures for BGP, comparison of these security protocols and their deployment issues. At the end we propose new security solution that is Defensive Routing Policy (DRP) to prevent BGP from malicious attacks and misconfigurations. DRP is operationally deployable and very effective to solve BGP problems.

In the recent year, System-on-Chip (SoC) has become a popular and important issue. As the environment of the SoC design becomes more and more complex. The issue of system verification becomes more important. In previous, the intellectual property (IP) was developed dependently. Every designer just designed the IP without integrated with others. But with the complexity of the environment increasing, more and more IPs are integrated into a system. Even though the verification plans are more complex, but some protocol errors can also not found by designers. Some incautious behavior may cause the system deadlock or in a jam. Some research use protocol checker to verify bus protocol, but they can¡¦t synthesize, so we propose a rule-based and synthesizable style protocol checker(AXIChecker) to verify the transactions on the AXI bus conform the AMBA 3.0(AXI) protocol or not.

A wireless sensor network (WSN) is comprised of a few hundred or thousand au-tonomous sensor nodes spatially distributed over a particular region. Each sensornode is equipped with a wireless communication device, a small microprocessor, anda battery-powered energy source. Typically, the applications of WSNs such as habitatmonitoring, re detection, and military surveillance, require data collection, process-ing, and transmission among the sensor nodes. Due to their energy constraints andhostile environments, the main challenge in the research of WSN lies in prolongingthe lifetime of WSNs.In this dissertation, we present four dierent topology management protocols forK-coverage and load balancing to prolong the lifetime of WSNs.First, we present a Randomly Ordered Activation and Layering (ROAL) protocolfor K-coverage in a stationary WSN. The ROAL suggests a new model of layer cov-erage that can construct a K-covered WSN using the layer information received fromits previously activated nodes in the sensing distance. Second, we enhance the faulttolerance of layer coverage through a Circulation-ROAL (C-ROAL) protocol. Us-ing the layer number, the C-ROAL can activate each node in a round-robin fashionduring a predened period while conserving reconguration energy. Next, MobilityResilient Coverage Control (MRCC) is presented to assure K-coverage in the presence of mobility, in which a more practical and reliable model for K-coverage with nodalmobility is introduced. Finally, we present a Multiple-Connected Dominating Set(MCDS) protocol that can balance the network trac using an on-demand routingprotocol. The MCDS protocol constructs and manages multiple backbone networks,each of which is constructed with a connected dominating set (CDS) to ensure a con-nected backbone network. We describe each protocol, and compare the performanceof our protocols with Dynamic Source Routing (DSR) and/or existing K-coveragealgorithms through extensive simulations.The simulation results obtained by the ROAL protocol show that K-coverage canbe guaranteed with more than 95% coverage ratio, and signicantly extend networklifetime against a given WSN. We also observe that the C-ROAL protocol provides abetter reconguration method, which consumes only less than 1% of the recongura-tion energy in the ROAL protocol, with a greatly reduced packet latency. The MRCCprotocol, considering the mobility, achieves better coverage by 1.4% with 22% feweractive sensors than that of an existing coverage protocol for the mobility. The resultson the MCDS protocol show that the energy depletion ratio of nodes is decreasedconsequently, while the network throughput is improved by 35%.

When data streams transmitted on the networks include wire and wireless parts, the utilizations of bandwidth are usually not good on existing TCP protocol, that is because TCP is not designed for the wireless transferring at first. The SNOOP protocol suggests to cache the data streams from fixed stations to mobile hosts. And do local retransmissions when the data lost is still available on base stations. Our thesis supposes to modify the existing SNOOP protocol, then proving that it reduces many unnecessary timeout on the simulation result. Generating a loss notification back to the TCP sender when there is a packet loss on the wireless link. This notification makes TCP wait a short period of time while base stations is doing local retransmission. These series of mechanisms also avoid low transmit rate which occur when unnecessary timeouts. Besides we preserve the original advantages of SNOOP.

In cope with continuing growth of network functionality and new protocols, we proposed a reconfigurable framework of common architectures and differentiated architectures for network communication. Existing protocol components and new protocol components can then be organized on such framework as selections. According to cost, performance, and functional requirements of network design, desirable general or specialized network communication systems can be prototyped quickly. In order to verify the reconfiguration capability, in this research, we selected the Internet and associated protocols as an example. On the framework, we constructed these protocol functions. According to design requirements, we can reconfigure desirable network designs and evaluate their performance.