Earticle

The Digital controlled oscillator (DCO) is the core element of all digital phase locked loop (ADPLL) system. Here, we propose DCO structures with digital control, reduced hardware and low power consumption. Different DCOs are based on ring based topology having 3, 4 & 5 control bits. Number of control bits can be increased as per the requirement of output frequency range. DCOs using XOR as an inverter having NMOS and PMOS transistors in pull up and pull down switching networks are presented. Three bit DCO with NMOS control network shows frequency variations of [3.1763 - 3.5290] GHz with power consumption variations of [266.8491 - 293.6420] μW. Three bit DCO with PMOS network shows frequency variation of [1.9918 - 1.4313] GHz with power consumption variation of [46.1176 - 22.8450] μW. Four bit DCO with NMOS & PMOS control networks shows frequency variations of [3.2219 - 3.6114] GHz & [2.1328 - 1.4627] GHz respectively. Power consumption variations of [266.8491 - 294.9430] μW & [53.5188 - 22.8454] μW have been obtained for 4-bit DCO having NMOS & PMOS switch networks respectively. Finally the five bit DCO with NMOS & PMOS network shows output frequency range of [3.3050 - 3.5557] & [2.2579 - 1.4934] GHz. Power consumption of [266.8491 - 295.5983] μW & [61.3773 - 22.8453] μW have been reported with NMOS & PMOS network for 5-bit controlled DCO. Comparisons with earlier reported circuits have been made and reported design shows improvement over previous circuits.

A promising choice for signal generation in modern communications systems is direct digital frequency synthesis (DDFS) which is capable of well controlled, rapid changes in signal frequency, over a relatively large frequency range. Unfortunately, a conventional DDFS system requires a high frequency read only memory (ROM) which consumes most of the power. This paper describes a novel low complexity DDFS with smaller lookup table size and lesser hardware overhead. It is based on the Taylor series expansion method for sinusoidal and co-sinusoidal functions combined with an approximation algorithm. It has the advantages of high speed, low complexity, low computational delay and high spectral purity. The proposed DDFS has high SFDR (spurious free dynamic range) and the spectral purity can be as good as 135 dBc.

Smart Home technology is the integration of technology and services through home networking for a better quality of living. This paper provides a review of the recent developments in technologies for Smart Home Automation and Mobile IP and its potential application and integration to Smart Home systems. The principles of MIPv6 are adopted for providing mobility on the design of the architecture for MIP-Based Smart Home.

In this paper we present a secure patient medical images and authentication scheme which enhances the security, confidentiality and integrity of medical images transmitted through the Internet. This paper proposes a watermarking by invoking particle swarm optimization (PSO) technique in adaptive quantization index modulation and singular value decomposition in conjunction with discrete wavelet transform (DWT) and discrete cosine transform (DCT). The proposed approach promotes the robustness and watermarked image quality. The experimental results show that the proposed algorithm yields a watermark which is invisible to human eyes, robust against a wide variety of common attacks and reliable enough for tracing colluders.

Mobile agents’ paradigm wide acceptance depends on the ability to overcome its major problem of security. In this context, the major concern is the subtle issue of malicious hosts. Many solutions had been proposed in this area, varying from tamper free hardware to pure software protocols. Nevertheless, neither of them is fully satisfactory. This paper investigates the problem on a novel basis. It develops an incremental protocol giving the opportunity to appreciate the benefit of making weaker hints available (.i.e., information about the lower suspicious character of malicious hosts). Upon these hints and progressively, the protocol can unambiguously confirm the stronger malicious character of hosts by a process of truth enforcement. This paper develops the issues raised by the protocol and validates the protocol efficiency in regard to the weaker hints use to verify the veracity of what we have called explicitly the lower suspicious character of a host.