Archive forNovember, 2008

THE INTEL MMX™ TECHNOLOGY

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The Intel MMX™ technology comprises a set of instructions to the Intel architecture (IA) that are designed to greatly enhance the performance of advanced media and communications applications. These extensions (which include new registers, data types and instructions) are combined with the Single Instruction, Multiple Data (SIMD) Execution model to accelerate the performance of applications such as motion video, combined graphics with video, image processing, audio synthesis, speech synthesis and compression, 2D and 3D graphics, which typically use compute-intensive algorithms to accomplish the purpose. All existing soft wares that don’t make use of this technology will also run on the processor without modification. Presented below is an elementary treatise on this technology in a programmer’s point of view.  

Overview of the MMX™ Technology Programming Environment     

MMX™ technology provides the following new extensions to the Intel Architecture (IA) programming environment. 

Eight MMX™ registers (MM0 to MM7).

Four MMX™ data types 

The MMX ™ instruction set

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Intrusion Detection

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In the last three years, the networking revolution has finally come of age. More than ever before, we see that the Internet is changing computing as we know it. The possibilities and opportunities are limitless; unfortunately, so too are the risks and chances of malicious intrusions.

It is very important that the security mechanisms of a system are designed so as to prevent unauthorized access to system resources and data. However, completely preventing breaches of security appear, at present, unrealistic. We can, however, try to detect these intrusion attempts so that action may be taken to repair the damage later. This field of research is called Intrusion Detection.

Anderson, while introducing the concept of intrusion detection in 1980, defined an intrusion attempt or a threat to be the potential possibility of a deliberate unauthorized attempt to

·         access information,

·         manipulate information, or

·         render a system unreliable or unusable.

Since then, several techniques for detecting intrusions have been studied. This paper discusses why intrusion detection systems are needed, the main techniques, present research in the field, and possible future directions of research.

SECURITY POLICY

A Security Policy defines what is permitted and what is denied on a system. There are two basic philosophies behind any security policy:

·         Prohibitive where everything that is not expressly permitted is denied.

·         Permissive where everything that is not expressly denied is permitted.

Elements of a System’s Security

A computer system can be considered as a set of resources which are available for use by authorized users. A paper by Donn P outlines six elements of security that must be addressed by a security administrator. It is worth evaluting any tool by determining how it address these six elements.

·         Availability - the system must be available for use when the users need it. Similarly, critical data must be available at all times.

·         Utility - the system, and data on the system, must be useful for a purpose.

·         Integrity - the system and its data must be complete, whole, and in a readable condition.

·         Authenticity - the system must be able to verify the identity of users, and the users should be able to verify the identity of the system.

·         Confidentiality - private data should be known only to the owner of the data, or to a chosen chosen few with whom the owner shares the data.

·         Possession - the owners of the system must be able to control it. Losing control of a system to a malicious user affects the security of the system for all other users.

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LASER Communication

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Laser communications offer a viable alternative to RF communications for inter satellite links and other applications where high-performance links are a necessity. High data rate, small antenna size, narrow beam divergence, and a narrow field of view are characteristics of laser communications that offer a number of potential advantages for system design.

Lasers have been considered for space communications since their realization in 1960. Specific advancements were needed in component performance and system engineering particularly for space qualified hardware. Advances in system architecture, data formatting and component technology over the past three decades have made laser communications in space not only viable but also an attractive approach into inter satellite link applications.

Information transfer is driving the requirements to higher data rates, laser cross -link technology explosions, global development activity, increased hardware, and design maturity. Most important in space laser communications has been the development of a reliable, high power, single mode laser diode as a directly modulable laser source. This technology advance offers the space laser communication system designer the flexibility to design very lightweight, high bandwidth, low-cost communication payloads for satellites whose launch costs are a very strong function of launch weigh. This feature substantially reduces blockage of fields of view of most desirable areas on satellites. The smaller antennas with diameter typically less than 30 centimeters create less momentum disturbance to any sensitive satellite sensors. Fewer on board consumables are required over the long lifetime because there are fewer disturbances to the satellite compared with heavier and larger RF systems. The narrow beam divergence affords interference free and secure operation.

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LED wireless

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Billions of visible LEDs are produced each year, and the emergence of high brightness AlGaAs and AlInGaP devices has given rise to many new markets. The surprising growth of activity in, relatively old, LED technology has been spurred by the introduction of AlInGaP devices. Recently developed AlGaInN materials have led to the improvements in the performance of bluish-green LEDs, which have luminous efficacy peaks much higher than those for incandescent lamps. This advancement has led to the production of large-area full-color outdoors LED displays with diverse industrial applications.

                                The novel idea of this article is to modulate light waves from visible LEDs for communication purposes. This concurrent use of visible LEDs for simultaneous signaling and communication, called iLight, leads to many new and interesting applications and is based on the idea of fast switching of LEDs and the modulation visible-light waves for free-space communications. The feasibility of such approach has been examined and hardware has been implemented with experimental results. The implementation of an optical link has been carried out using an LED traffic-signal head as a transmitter. The LED traffic light (fig 1 below) can be used for either audio or data transmission.

Audio messages can be sent using the LED transmitter, and the receiver located at a distance around 20 m away can play back the messages with the speaker. Another prototype that resembles a circular speed-limit sign with a 2-ft diameter was built. The audio signal can be received in open air over a distance of 59.3 m or 194.5 ft. For data transmission, digital data can be sent using the same LED transmitter, and the experiments were setup to send a speed limit or location ID information.

                                The work reported in this article differs from the use of infrared (IR) radiation as a medium for short-range wireless communications. Currently, IR links and local-area networks available. IR transceivers for use as IR data links are widely available in the markets. Some systems are comprised of IR transmitters that convey speech messages to small receivers carried by persons with severe visual impairments. The Talking Signs system is one such IR remote signage system developed at the Smith-Kettlewell Rehabilitation Engineering Research center. It can provide a repeating, directionally selective voice message that originates at a sign. However, there has been very little work on the use of visible light as a communication medium.

                                The availability of high brightness LEDs make the visible-light medium even more feasible for communications. All products with visible-LED components (like an LED traffic signal head) can be turned into an information beacon. This iLight technology has many characteristics that are different from IR. The iLight transceivers make use of the direct line-of-sight (LOS) property of visible light, which is ideal in applications for providing directional guidance to persons with visual impairments. On the other hand, IR has the property of bouncing back and forth in a confined environment. Another advantage of iLight is that the transmitter provides easy targets for LOS reception by the receiver. This is because the LEDs, being on at all times, are also indicators of the location of the transmitter. A user searching for information has only to look for lights from an iLight transmitter. Very often, the device is concurrently used for illumination, display, or visual signage. Hence, there is no need to implement an additional transmitter for information broadcasting. Compared with an IR transmitter, an iLight transmitter has to be concerned with even brightness. There should be no apparent difference to a user on the visible light that emits from an iLight device.

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Light Trees

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Today, there is a general consensus that, in the near future, wide area networks (WAN)(such as, a nationwides backbone network) will be based on Wavelength Division Multiplexed (WDM) optical networks. One of the main advantages of a WDM WAN over other optical technologies, such as, Time Division Multiplexed (TDM) optical networks, is that it allows us to exploit the enormous bandwidth of an optical fiber (up to 50 terabits bits per second) with requiring electronic devices, which operate at extremely high speeds.

The concept of light tree is introduced in a wavelength routed optical network, which employs wavelength -division multiplexing (WDM).

Depending on the underlying physical topology networks can be classified into three generations:

ü First Generation: these networks do not employ fiber optic technology; instead they employ copper-based or microwave technology. E.g. Ethernet.

ü Second Generation: these networks use optical fibers for data transmission but switching is performed in electronic domain. E.g. FDDI.

ü Third Generation: in these networks both data transmission and switching is performed in optical domain. E.g. WDM.

WDM wide area networks employ tunable lasers and filters at access nodes and optical/electronic switches at routing nodes. An access node may transmit signals on different wavelengths, which are coupled into the fiber using wavelength multiplexers. An optical signal passing through an optical wavelength-routing switch (WRS) may be routed from an output fiber without undergoing opto-electronic conversion.

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