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Cooperative communication using decode and forward (DF)-based distributed relays is one important solution to achieve better connectivity and higher data rates in wireless fading channels. In distributed relay networks, each relay has an independent local oscillator which when unsynchronized results in the presence of multiple carrier frequency offsets (CFOs) at the destination. The maximum likelihood...
In this paper, we consider the half-duplex cooperative multiple-access channel (CMAC) in block-fading channels. Each link employs orthogonal frequency division multiplexing (OFDM) which is suitable for high rate wideband transmission and the modulated symbols are drawn from a finite constellation set. We first obtain the diversity order of the CMAC, as a function of the time sharing variables of the...
In this paper, we consider the half-duplex relay channel. We seek to design multiple turbo codes to minimize the information outage in the block fading channel. An analysis on the diversity order of the relay channel, which depends on the time sharing variable and the rate of the code, is given for practical modulations. We also give a code structure for the multiple turbo codes to achieve the full...
Cooperative system has been receiving considerable attention recently as an effective approach to improve transmission reliability in slow fading wireless channels. In this paper, we exploit cooperative diversity in multiple relay networks to improve the performance of Gaussian source transmission with layered broadcast coding. Specifically, we study the distortion performance of two amplify-and-forward...
In this paper, we consider the half-duplex cooperative multiple-access channel (CMAC). We seek to design multiple turbo codes to minimize the information outage in the block fading channel. Since we consider an outage to occur even if the message of one of the sources fails to be decoded successfully, we employ a joint network-channel coding approach in our design. The codes are optimized using the...
Two-way relaying is an effective approach to exchange information between two simultaneously transmitting sources in wireless fading environment. Space-time non-regenerative relaying aids to keep the relay hardware simple and cheap. Accurate estimates for the channel and carrier frequency offset (CFO) are required by the receiver to reap the benefits from relaying. In this paper, we propose a training...
Cooperative communications have received considerable attention for wireless multimedia applications as a means to improve reliability. To exploit such cooperation over slow fading channels, we propose to adaptively and efficiently transmit a layered source over a non-regenerative relay network. Specifically, we jointly determine the number of source encoder layers, the transmission rate and power...
Cooperative relaying is an effective approach to combat wireless fading. However, the reliability enhancements depend strongly on the accuracy of the carrier frequency offset (CFO) compensation and channel estimation algorithms. In this paper, we show that CFO compensation at relay is necessary in non-regenerative OFDM based wireless relay networks with relays employing space-time coding. A simple...
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