1719358
A BPSK demodulator circuit using an anti-parallel synchronization loop
A novel anti-parallel loop carrier synchronization method for BPSK demodulation is proposed and demonstrated. The method contains an anti-parallel dual loop, which locks the carrier by its upper loop and lower loop alternately, according to the data bits contained in the received BPSK signal. Simulation and experimental results are shown along with BER performance.
6457216
A CMOS Direct-Digital BPSK Modulator Using an Active Balun and Common-Gate Switches
A 0.18 mum CMOS binary phase shift keying (BPSK) modulator circuit is proposed and demonstrated that can achieve high data rates and strong carrier suppression while having low DC power consumption and a very compact layout. The modulator accepts a single-ended microwave signal (2.4 GHz) and converts it to a balanced signal using an active balun. Complementary common-gate switches are then used to select one of the two balun outputs in correspondence with the digital data to produce BPSK modulation. Excellent performance is obtained with measured phase and amplitude errors of less than 1deg and 0.1 dB, respectively, and data rates up to 200 Mbps with a carrier frequency of 2.4 GHz. The insertion loss for the modulator is approximately 3 dB. Additionally, the active balun provides input matching and obtains an input reflection coefficient of -13 dB. The circuit layout area is 310 mumtimes260 mum and the power consumption is 7.2 mW.
5682504
An Efficient XPath Query Processor for XML Streams
Streaming XPath evaluation algorithms must record a potentially exponential number of pattern matches when both predicates and descendant axes are present in queries, and the XML data is recursive. In this paper, we use a compact data structure to encode these pattern matches rather than storing them explicitly. We then propose a polynomial time streaming algorithm to evaluate XPath queries by probing the data structure in a lazy fashion. Extensive experiments show that our approach not only has a good theoretical complexity bound but is also efficient in practice.
10204848
The nonhomomorphicity of S-boxes
In this paper we introduce the concept of kth order nonho momorphicity of mappings or S boxes as an alternative indicator that forecasts nonlinearity characteristics of an S box where k is even Main results of this paper include we show that nonhomomorphicity especially the th order nonhomomorphicity can be precisely expressed by using other important nonlinear indicators of an S box we estab lish tight lower and upper bounds on the nonhomomorphicity of S boxes we identify the mean of nonhomomorphicity over all the S boxes with the same size and the relative nonhomomorphicity of an S box both of which are useful in estimating statistically the nonhomomorphicity of an S box
15990035
Content-based retransmission for 3-D wavelet video streaming on the Internet
Improving the QoS of video streaming with packet loss is a challenging topic of research. In this paper, we propose a novel content-based retransmission scheme to address this issue. The basic idea is to jointly consider the packets' contents and the channel conditions to optimize QoS. The goal is to deliver the best quality of video possible under the same channel condition. Using the proposed retransmission scheme, we have designed a 3D wavelet video streaming system. Simulation results show that the content-based retransmission can improve the video quality by more than 2 dB compared with the existing non-content-based delay-constrained retransmission when the channel loss rate is high.
13563503
A testbed for quantitative assessment of intrusion detection systems using fuzzy logic
The current intrusion detection system (IDS) technology is a major investment for a firm and its evaluation is desired prior to a commitment. A testbed compares different IDSs on a common platform. A major challenge in evaluating IDSs stems from the fact that they are generally tested in specific environments. A real-world environment could be different from the environment designed for a testbed. The results obtained, from such testbeds, may not be accurate and reliable. Hence, a quantitative and metrics based evaluation of IDSs is desired. We propose testbed for evaluating intrusion detection systems (TIDeS), that allows a user to select the best IDS for a specific customized environment. A quantitative analysis is provided by TIDeS, using fuzzy logic, under varying network loads. We also propose robust metrics to evaluate an IDS. We follow up with recommendations, based on our experience, on the general practices in the field of IDSs.
790881
Compact and unforgeable key establishment over an ATM network
Authenticated session key establishment is a central issue in network security. This paper addresses the question of whether we can design a compact, efficient and authenticated key establishment protocol that has the following two properties: (1) each message exchanged between two participants can be transferred in a short packet such as an ATM cell whose payload has only 384 bits, and (2) messages that carry key materials are unforgeable and nonrepudiatable without the involvement of a trusted key distribution center. We discuss why the answer to this question is negative if one follows the currently standard approach to key establishment, namely employing secret/public key encryption and, possibly, digital signature. We then present a number of protocols that represent a positive answer to the question. Our protocols are all based on a cryptographic primitive called "signcryption" that fulfils both the functions of digital signature and public key encryption with a cost far smaller than that required by "digital signature followed by encryption".