In this paper, a single-hop single-relay system with a direct link between the source and the destination is considered when the relay operates in the half-duplex mode. Motivated by the concept of signal space diversity, this paper introduces signal space cooperation, in which cooperation between the source and the relay is achieved using a novel constellation design approach. In this approach, the original constellation is expanded so that each member of the new constellation inherits its components from at least two members of the original constellation. The expanded constellation enables the relay to extract the required information in order to cooperate in the relay phase, and it helps the destination to effectively combine received signals during the broadcast phase and the relay phase. The analytical study of the proposed scheme leads to the development of two design criteria for the constellation expansion approach. The proposed design criteria aim at maximizing the relay role in the cooperative scheme by increasing the performance of the source-relay link. In this way, the source and the relay can effectively cooperate in order to maximize the overall performance of the system. The signal space cooperative scheme can be used for any constellation size without incurring significant complexity overhead to the system. Numerical results depict superior performance in comparison with other cooperative schemes such as the adaptive decode and forward and the distributed turbo code schemes.

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In this paper, the use of structural behavior of communication protocols in designing new covert channels is investigated. In this way, a new covert transmitter is designed based on a modified CSMA protocol that enables the transmitter to embed a covert message in its overt traffic. The proposed scheme provides high covert rate without compromising the stealthiness of the channel.

Legal liability is the legal bound obligation to pay debts. In law, a person is legally liable when he/she is financially and legally responsible for something. Legal liability concerns both civil law and criminal law. Legal liability can arise from various areas of law, such as contracts, tort judgments or settlements, taxes, or fines given by government agencies. Liabilities may be covered by insurance, although typically insurance covers liability arising from negligent torts rather than intentional wrongs or breach of contract. Liability may also be imposed joint and severally in certain cases. Liabilities arising from a contract to borrow money are debt. Children's rights are provided by a large number of laws-some that specifically were enacted to protect children, and others that contain just a few sections that pertain to children but provide them with essential rights. There are numerous pieces of legislation that provide children with rights in the areas of education, medicine, employment and the justice system. Given the volume and complexity of these laws, this report provides a necessarily broad overview of the substantive pieces of legislation as they affect children's rights in these areas. Therefore daily-increase of using bicycle and other dangerous tools may cause real damages for others. Also it is because of mental diseases which may attract the attention of law makers and specialists of law for the importance of compensation of any damages resulted by interdicts. The issue is not stupid civil liability and/or any differences between stupid elders. Civil liability of any functions insane minor is the real aim of this paper. As a result, it is conditional for damaged person to prove any failure of supervisor in order to be entitled for any compensation of damages. In case of any refer to supervisor to discredit for receipt of damages; it seems that there is no more difference among Iranian, England and Switzerland Laws. In none of the mentioned laws it is accepted for any refer to discredit because of his/her faults as well.

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