96 research outputs found

    Reed Solomon Coded Cooperation Scheme In Mobile Communication Networks And Application

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    Coded cooperative communication technique utilizes single antenna mobiles in a multi-user environment that share their antennas and incorporates channel coding in order to achieve transmit diversity. This thesis presents a new coded cooperation scheme based on Reed Solomon (RS) codes. The RS codes are very effective in correcting random symbol errors and random burst errors over wireless fading channels. The new coded cooperation system splits the data into two frames, using a mask vector arithmetic operation. The new scheme offers significant diversity gain improvement as compared to the renowned coded cooperation scheme that utilizes the Rate-Compatible Punctured Convolutional Code (RCPC). This work also derives the mathematical outage probability expressions for new RS coded cooperation scheme that proves its capacity to achieve full diversity gain

    An Outage Probability in Cooperative MIMO Under Slow Fading Channel

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    Slow fading channel one of the most important channels which appears widely in cellular mobile system. Although, it has several problems such as bad effects of fading which cause an attenuation to the signal. This paper presents a new scheme in cooperative communication system under slow fading channel to enhance and increase the quality of communication systems performance. This new scheme is called a cooperative multiple input–multiple output Antenna. The main idea of this scheme depends on transmitting multi copy of message via tow paths. Its' performance has compared with MIMO technique in term of outage probability. Thus, the negative effects of fading are mitigated and the outage probability is enhanced. Furthermore, the reliability in communication system under slow fading channel has improved

    Iterative decoding scheme for cooperative communications

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    NB-JNCD Coding and Iterative Joint Decoding Scheme for a Reliable communication in Wireless sensor Networks with results

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    Privacy threat is a very serious issue in multi-hop wireless networks (MWNs) since open wireless channels are vulnerable to malicious attacks. A distributed random linear network coding approach for transmission and compression of information in general multisource multicast networks. Network nodes independently and randomly select linear mappings from inputs onto output links over some field. Network coding has the potential to thwart traffic analysis attacks since the coding/mixing operation is encouraged at intermediate nodes. However, the simple deployment of network coding cannot achieve the goal once enough packets are collected by the adversaries. This paper proposes non-binary joint network-channel coding for reliable communication in wireless networks. NB-JNCC seamlessly combines non-binary channel coding and random linear network coding, and uses an iterative two-tier coding scheme that weproposed to jointly exploit redundancy inside packets and across packets for error recovery

    Analysis of hybrid-ARQ based relaying protocols under modulation constraints

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    In a seminal paper published in 2001, Caire and Tuninetti derived an information theoretic bound on the throughput of hybrid-ARQ in the presence of block fading. However, the results placed no constraints on the modulation used, and therefore the input to the channel was Gaussian. The purpose of this thesis is to investigate the impact of modulation constraints on the throughput of hybrid-ARQ in a block fading environment. First, we consider the impact of modulation constraints on information outage probability for a block fading channel with a fixed length codeword. Then, we consider the effect of modulation constraints upon the throughput of hybrid-ARQ, where the rate of the codeword varies depending on the instantaneous channel conditions. These theoretical bounds are compared against the simulated performance of HSDPA, a newly standardized hybrid-ARQ protocol that uses QPSK and 16-QAM bit interleaved turbo-coded modulation. The results indicate how much of the difference between HSDPA and the previous unconstrained modulation bound is due to the use of the turbo-code and how much is due to the modulation constraints. (Abstract shortened by UMI.)

    Destination Cooperation in Interference Channels

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    Multiple Input Multiple Output (MIMO) techniques are used to exploit spatial diversity and to achieve high bit rates required for emerging multimedia applications. To achieve this spatial diversity, more than one antenna have to be collocated at the transmitter and/or receiver nodes and the separation between those antenna has to be more than half a wavelength to ensure that the signals will experience different channel fading coefficients. One major drawback of this technique which makes it almost impossible to implement on handheld devices is the dimension of these devices. Cooperative communication can be used to achieve the diversity gains typical of MIMO without the need for multiple antennas on the mobile units. Diversity is attained through collaboration between nodes in the wireless network. In wireless communications, cooperative diversity improves throughput and reliability. To effectively combat multipath fading in wireless networks, we develop energy efficient protocols that employ some cooperation among receiving nodes. Motivated by the very promising results of cooperative diversity for both uncoded and coded systems as well as the substantial demand for higher data rates; in this thesis, we investigate the 2-user and 3-user destination cooperation in interference channels. We develop a collaboration protocol for the 2-user and 3-user models which is based on the fact that the information presents at one destination node can help in increasing the chance of correctly decoding the previously not decodable information at another destination node. Furthermore, we introduce network coding in the 3-user model and we show that network coding achieves further substantial gain. We demonstrate that the 2-user case outperforms the baseline scheme using orthogonal channels by far. This is due to the cooperative communication. In the cooperative scheme, the receiver nodes in the first time slot, decode the received information from both sources while in the second time slot they cooperate. The scheme provides both diversity and coding gain. Furthermore, we show that an enhanced scheme which exploits the unused information available at each destination node improves the outage probability. We present the simulation results of various scenarios that illustrate the efficiency of employing such techniques with and without channel coding. We show how the SNR required for obtaining a certain frame error rate varies with the distance between destination nodes. We also show a comparable analysis between the 2-user and 3-user destination cooperation in interference channels on one hand and the baseline orthogonal scheme on the other hand

    Wireless industrial monitoring and control networks: the journey so far and the road ahead

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    While traditional wired communication technologies have played a crucial role in industrial monitoring and control networks over the past few decades, they are increasingly proving to be inadequate to meet the highly dynamic and stringent demands of today’s industrial applications, primarily due to the very rigid nature of wired infrastructures. Wireless technology, however, through its increased pervasiveness, has the potential to revolutionize the industry, not only by mitigating the problems faced by wired solutions, but also by introducing a completely new class of applications. While present day wireless technologies made some preliminary inroads in the monitoring domain, they still have severe limitations especially when real-time, reliable distributed control operations are concerned. This article provides the reader with an overview of existing wireless technologies commonly used in the monitoring and control industry. It highlights the pros and cons of each technology and assesses the degree to which each technology is able to meet the stringent demands of industrial monitoring and control networks. Additionally, it summarizes mechanisms proposed by academia, especially serving critical applications by addressing the real-time and reliability requirements of industrial process automation. The article also describes certain key research problems from the physical layer communication for sensor networks and the wireless networking perspective that have yet to be addressed to allow the successful use of wireless technologies in industrial monitoring and control networks
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