Current Issue : October - December Volume : 2013 Issue Number : 4 Articles : 4 Articles
In this article, we investigate the information-theoretical performance of a cooperative orthogonal frequency division\r\nmultiplexing (OFDM) system with imperfect channel estimation. Assuming the deployment of training-aided channel\r\nestimators, we derive a lower bound on the achievable rate for the cooperative OFDM system with amplify-andforward\r\nrelaying over frequency-selective Rayleigh fading channels. The bound is later utilized to allocate power\r\namong the training and data transmission phases. Numerical results demonstrate that the proposed power allocation\r\nscheme brings between 5 and 19% improvement depending on the level of signal-to-noise ratio and relay locations....
The newly developed 2nd generation standard for digital video broadcasting (DVB-T2) emerges as a significant\r\nupgrade over its first generation predecessor DVB-T. The DVB-T2 standard targets an increased system throughput\r\nby at least 30% over the DVB-T. This article introduces algorithms in the signal processing chain to improve the\r\nmobile operation for DVB-T2. The proposed modified synchronization blocks, along with the improved channel\r\nestimation, show significant improvement compared to the results reported in the DVB-T2 implementation guide.\r\nIn addition, state-of-the-art low-complexity algorithms in the bit processing chain, particularly in the LDPC decoder,\r\nare used to provide robustness and support throughput increase, while reducing the implementation complexity.\r\nThe integrated system is simulated including implementation effects. The simulation results confirm the enhanced\r\nperformance of the developed integrated model and provide better results compared to those reported in\r\nliterature....
We consider an energy harvesting transmitter broadcasting individual data to two receivers. Data packets intended\r\nfor each user are assumed to arrive at arbitrary but known instants. The goal is to minimize the total transmission time\r\nof the packets arriving within a certain time window, using the energy harvested during this time. Energy harvests are\r\nalso modelled to occur at known discrete instants. An achievable rate region with structural properties satisfied by the\r\ntwo-user additive white Gaussian noise broadcast channel capacity region is assumed. Structural properties of power\r\nand rate allocations are established, as well as the uniqueness of the optimal policy. An iterative algorithm, DuOpt, is\r\ndevised for efficient solution of this offline problem. DuOpt is compared with the sequential unconstrained\r\nminimization (SUMT) solution technique on randomly generated problem instances and is observed to solve the\r\nproblem two orders of magnitude faster on average than SUMT....
Mobile TV has become a reality offered on several mobile delivery systems. Among them is the Advanced Television System\r\nCommittee (ATSC) system formobile and handheld digital television services, known as ATSCMobile DTV or ATSC M/H, which\r\nhas moved from standardization to implementation. As the North American broadcast industry is preparing to provide Mobile\r\nDTV service to consumers, this work discusses important technical parameters that affect the TV service quality and capacity.\r\nSince additional error correction mechanisms were added to overcome mobile transmission problems, the available payload for\r\nM/H services is limited. This creates a need to efficiently use the available M/H bandwidth.The paper aims to optimize theMobile\r\nDTV service capacity while maintaining an acceptable perceived quality. It presents tradeoffs between several factors affecting\r\nservice capacity and signal robustness, which is prominent for designing Mobile TV broadcasting scenarios....
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