A low-power highly digitized receiver for 2.4-GHz-band GFSK applications

This paper describes the design and measurement results of a low-power highly digitized receiver for Gaussian frequency-shift keying modulated input signals at 2.4 GHz. The RF front-end has been based on a low-IF architecture and does not require any variable gain or filtering blocks. The full dynamic range of the low-IF signal is converted into the digital domain by a low-power high-resolution time-continuous SigmaDelta analog-to-digital converter (ADC). This leads to a linear receive chain without limiters. A fifth-order poly-phase loop filter is used in the complex SigmaDelta ADC. The digital block performs filtering and demodulation. Channel filtering is combined with matched filtering and the suppression of noise resulting from the SigmaDelta ADC. The high degree of digitization leads to design flexibility with respect to changing standards and scalability in future CMOS generations. The receiver has been realized in a standard 0.18-mum CMOS process and measures 3.5 mm². The only external components are an antenna filter and a crystal. The power consumption is only 32 mW in the continuous mode, which is at least a factor of two lower than state-of-the-art CMOS receivers     

Lossless quantization of Hadamard transform coefficients

This paper shows that an nx1 integer vector can be exactly recovered from its Hadamard transform coefficients, even when 0.5n log (2)(n) of the (less significant) bits of these coefficients are removed. The paper introduces a fast "lossless" dequantization algorithm for this purpose. To investigate the usefulness of the procedure in data compression, the paper investigates an embedded block image coding technique called the "LHAD" based on the algorithm. The results show that lossless compression ratios close to the state of the art can be achieved, but that techniques such as CALIC and S+P still perform better.     

Internet telephony signaling

The term “multimedia session” refers to the integration of data coming from various sources, such as sound, video and text, within a computer application. Telephony over the Internet is among the more exciting current developments. The signaling of a telephone call consists of the set of messages and procedures used to establish a connection, to request changes in communication bandwidth, to obtain the message status for the end points participating in the conversation, and to close the link. At present there exist two competing signaling protocols for Internet telephony, viz., the H.323 protocol sponsored by the ITU and the Session Invitation Protocol (SIP) sponsored by the IETF. Each of them supplies its own signaling mechanisms.

In this paper, these two protocols in terms of their main functionalities are compared. Based on the results of this comparison, a Client/Server architecture for the development of an application that supports a basic SIP implementation, as well as the formulation of requests allowing the establishment and the disconnection of communications between a number of users in a multimedia session are then defined.     

Supersymmetric standard model from the heterotic string

We present a [FORMULA: SEE TEXT] orbifold compactification of the E8xE8 heterotic string which leads to the (supersymmetric) standard model gauge group and matter content. The quarks and leptons appear as three 16-plets of SO(10), whereas the Higgs fields do not form complete SO(10) multiplets. The model has large vacuum degeneracy. For generic vacua, no exotic states appear at low energies and the model is consistent with gauge coupling unification. The top quark Yukawa coupling arises from gauge interactions and is of the order of the gauge couplings, whereas the other Yukawa couplings are suppressed.     

Heterodyne beatings between frequency-shifted feedback lasers

Frequency-shifted feedback (FSF) lasers are potential candidates for long distance telemetry due to the appearance of beatings in the noise spectrum at the output of a homodyne interferometer: the frequencies of these beatings vary linearly with the path delay. In this Letter we demonstrate that these beatings also occur in the heterodyne mixing of two identical, but distinct, FSF lasers. This phenomenon is explained by the passive cavity model and is exploited to characterize the time-spectrum properties of FSF lasers. Consequences on telemetry with FSF lasers are presented.     

Compact Modeling Methodology of Strained-Si Channel-on-Insulator (SSOI) MOSFETs

Compact physical models for SSOI MOSFETs are presented. The models consider specific features for strained-Si devices including SSOI such as mobility enhancement, band offsets, junction capacitance, and self-heating effects. All of the floating-body current components in conventional SOI structure, which are generation/recombination current, reverse-bias (band-to-band and trap-assisted) junction tunneling currents, gate-induced drain leakage current, gatebody oxide tunneling current, and impact ionization current are applied to the SSOI device, and their effects are discussed. The model validity is confirmed by fabricated 70?nm bulk-Si (control) and strained-Si devices.     

Quadratic functions with prescribed spectra

We study a class of quadratic p-ary functions ${{\mathcal{F}}_{p,n}}$ from ${\mathbb{F}_{p^n}}$ to ${\mathbb{F}_p, p \geq 2}$ , which are well-known to have plateaued Walsh spectrum; i.e., for each ${b \in \mathbb{F}_{p^n}}$ the Walsh transform ${\hat{f}(b)}$ satisfies ${|\hat{f}(b)|^2 \in \{ 0, p^{(n+s)}\}}$ for some integer 0 ≤ s ≤ n ? 1. For various types of integers n, we determine possible values of s, construct ${{\mathcal{F}}_{p,n}}$ with prescribed spectrum, and present enumeration results. Our work generalizes some of the earlier results, in characteristic two, of Khoo et. al. (Des Codes Cryptogr, 38, 279–295, 2006) and Charpin et al. (IEEE Trans Inf Theory 51, 4286–4298, 2005) on semi-bent functions, and of Fitzgerald (Finite Fields Appl 15, 69–81, 2009) on quadratic forms.