An Electromagnetic Analysis of Noise-Based Intrinsically Secure Communication in Wireless Systems

An Electromagnetic Analysis of Noise-Based Intrinsically Secure Communication in Wireless Systems The research on noise-based secure communication systems is mainly carried out from an information theoretical point of view, and is focused on evaluation in different communication conditions of the secrecy capacity, which is defined as the maximum achievable perfect secrecy rate, where the perfect secret rate is the amount of information that can be sent not only reliably but also confidentially. He noted that the channel capacity of the authorized channel is higher than the channel capacity of the eavesdropper, and one coding strategy is able to transmit information to the authorized receiver with a vanishing block-code error probability in a completely secure way, at a rate limited by the difference between the authorized and eavesdropper channel capacity. This causes a decrease in the channel capacity of the unauthorized receiver compared to the authorized receiver, which can transmit information buried in the additional noise affecting the eavesdropper. In this paper, it will be shown that, in the noise-based unconditionally secure communication systems, the degrees of freedom of the electromagnetic field are used in a third way. Paralleling the analysis undertaken in, it takes advantage of the concept of the number of degrees of freedom (NDF) of the electromagnetic field, defined as the minimum number of functions required to represent the field on an observation manifold within a given representation error, fixed by the noise corrupting the observed field. Successively, in a seminal paper, Wyner suggested that the presence of additional noise when information is tapped from a line makes the unauthorized channel noisier than the authorized channel. Broadly speaking, any antenna uses the available degrees of freedom of the electromagnetic field mainly following two possible goals: to concentrate (and possibly maximize) energy on the receiving antenna or to maximize the amount of information available on the receiving antenna. In this framework, an approach to obtain unconditionally secure communication based on the use of the degrees of freedom of the electromagnetic field is discussed. Signal and noise are transmitted at the same time using a strategy that avoids any increase in noise at the authorized receiver taking advantage of the degrees of freedom that are not used to transmit information. The physical mechanism at the basis of the secret communication is explained by means of the degrees of freedom of the field, which are able to convey information and noise in spatially orthogonal channels. As a final observation, in order to make the channel secure, a non-negligible percentage of the available power is radiated as artificial noise. According to some fundamental results of information theory, it is possible to hide information in the additional noise affecting the eavesdropper. Loosely speaking, the allocation of power to noise causes a decrease in the channel capacity of the system that follows logarithmic law.

Incidents in the Life of a Slave Girl Essay Example | Topics and Well Written Essays - 1500 words

Incidents in the Life of a Slave Girl - Essay Example â€Å" (7). Which is why Linda led a relatively happy life up until the age of six when her mother died. It was only then that she learned that she was to be a slave in the employ of her mother's former mistress. In Brent's own words; â€Å"Such were the unusually fortunate circumstances of my early childhood. When I was six years old, my mother died; and then, for the first time, I learned, by the talk around me, that I was a slave† (7). When her mistress dies and she is passed on to other masters, her life totally changes in such a manner that is is speedily robbed of her innocence. She is given to the Flint family headed by Dr. Flint. He was described as ; â€Å"... an epicure. The cook never sent a dinner to his table without fear and trembling; for if there happened to be a dish not to his liking, he would either order her to be whipped, or compel her to eat every mouthful of it in his presence. The poor, hungry creature might not have objected to eating it; but she did not object to having her master cram it down her throat till she choked† (13). She thwarts the sexual advances of Dr. Flint by consenting to having an affair with her white neighbor. That neighbor is named Mr. Sands, he fathers her two children named Benjamin and Ellen. It is important to note that Jacobs wrote her protagonists point of view in such a way that she thought it was better to live the life of a kept woman with mulatto children than to be the product of a sexual rape. It is the opinion of the author that because women slaves lead a different life than the white women, they are offered a different standard of morality than the free women. At the end of Linda's affair with Mr. Sands, he leaves her to go south. He takes a bride,fathers a child with her,purchases his children with Linda and treats them as slaves even when he promised her that he would free then, then becomes a congressman. Throughout the ordeal of Linda's life there was one constant personality who tr ied to stand up for her family no matter the cost, her grandmother known as Aunt Martha. She lived to see her grandchildren escape from slavery even though it meant losing them as family. She was a strong willed woman who stood up for herself and put fear into Dr. Flint. In one of the more famous scenes in the book she admonishes the doctor and tells him to "Get out of my house†¦ Go home and take care of your wife and children" (15). Aunt Martha, through the grace of the universe managed to gain her freedom when it was provided to her by a kindly white woman. The situation occurred this way; Dr. Flint chose to sell Aunt Martha after the death of her mistress because he thought her old and feeble. Nobody wanted to buy her on the auction block except for an old white woman who immediately granted her freedom upon the close of her sale. One of the most touching depictions of slavery in the book has to do with the method by which the slaves celebrate New Years Day. Their eve is spe nt among their family and little possessions as they await the decision of their master as to whether or not they will be sold to another master and permanently parted from their family the next day. Those up for sale can be heard begging the masters who are looking over the slaves like produce to â€Å"Please, massa, hire me this year. I will work _very_ hard, massa." (15). It is because of the way that the slave families find themselves separated and divided that Aunt Martha tries to buy the freedom of her grandchildren from their masters,

Individual Write-Up Essay Example | Topics and Well Written Essays - 1000 words

Individual Write-Up - Essay Example e going to visit Africa and more particularly Kenya, s as to go and watch the wild beast migration, based on what I have heard regarding Africa I prepared myself for the Stone Age life. Two days before our departure I had already parked all the things that I thought was necessary. I carried some of the most essential things, such as toothpaste, soap, spotlights, and camp knifes. My dad informed me of certain things like soap that could be bought when we got to Africa, but I could not dare leave my â€Å"Essential package† as I was not sure even if there were shops there. The day finally came, and we left for Africa, the fight took about 12 hours, as we had to make a stopover in Amsterdam. All through the flight, my mind was on the types of houses that I was going not just to see but live in. when the pilot announced the plane’s arrival in an hour, I was very excited because I was going to experience Africa for the very first time. The plane reached the Jomo Kenyatta International Airport and t my surprise there were no animals anywhere in sight all I could see were tall, beautiful houses like the ones back in Canada. Sensing my dismay my dad told me â€Å"I told you†, the animal park that we were supposed to go and see the wild beast migration was known as the Tsavo National Park, which was quite a long distance from Nairobi. I had found out from the internet about the wild beast migration, and I was looking forward to seeing the animals leap into the river and cross to the other side. I tried to anticipate how many animals would make it safely to the other side. To make the experience a unforgettable, my dad had arranged that we travel by train to the park. There are no electric trains in Kenya we had t use the old locomotives, which run on diesel apparently these trains were left by the colonial government decades ago. The trip t the park was full of adventure, the train tracks went through beautiful open country where we were able t see some wild animals