124,957 research outputs found
Equivalent Capacity-Based Joint Multilevel Coding and Space–Time Transmit Diversity Design
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Luby Transform Coding Aided Bit-Interleaved Coded Modulation for the Wireless Internet
No full textBit-Interleaved Coded Modulation using Iterative Decoding (BICM-ID) is amalgamated with Luby Transform (LT) coding. The resultant joint design of the physical and data link layer substantially improves the attainable Bit Error Rate (BER) performance. A Cyclic Redundancy Check (CRC) combined with a novel Log-Likelihood Ratio (LLR) based packet reliability estimation method is proposed for the sake of detecting and disposing of erroneous packets. Subsequently, bit-by-bit LT decoding is proposed, which facilitates a further BER improvement at a lower number of BICM-ID iterations. Finally, we revisit the pseudo random generator function used for designing the LT generator matrix
Serially Concatenated Luby Transform Coding and Bit-Interleaved Coded Modulation Using Iterative Decoding for the Wireless Internet
No full textIn Bit-Interleaved Coded Modulation (BICM) the coding and modulation schemes were jointly optimized for the sake of attaining the best possible performance when communicating over fading wireless communication channels. The iterative decoding scheme of BICM (BICM-ID) invoking an appropriate bit-to-symbol mapping strategy enhances its achievable performance in both AWGN and Rayleigh channels. BICM-ID may be conveniently combined with Luby Transform (LT) codes, which were designed for handling packetized wireless Internet data traffic in erasure channels without retransmitting the corrupted packets. By jointly designing a serially concatenated LT-BICM-ID code, an infinitesimally low Bit Error Rate (BER) is achieved for Signal to Noise Ratios (SNR) in excess of 7.5dB over wireless Internet type erasure channels contaminated by AWGN
A co-operative inquiry into the involvement of service users in mental health nurse education
No full textAssessment of damage tolerance levels in FRP ship structures
No full textThis work is concerned with the damage tolerance assessment of laminated composite structures used in ship structures. An intensive review has been carried out with regard to current experimental, analytical and numerical work on both laminates and structural elements. Particular attention has been focused on the problem of damage due to delamination and its structural consequences. Strength assessments of top hat stiffeners and tee joints has been carried out with a view to identifying regions most susceptible to delaminations. It has been shown that such regions are contained within the curved region of the overlaminate in both types of structural elements. Strain energy release rates and J-integral values have been calculated for specific cracks to determine their likelihood of propagation under a variety of loading conditions. Overall, a number of conclusions have been drawn with regard to single-skin marine FRP structures. For example, both the strength - and the energy - based approaches have predicted that a tee joint subjected to a 45 degree pull-off load, delaminations which are deep within the overlaminate are more likely to propagate than those close to the surface
Three-Dimensional EXIT Chart Analysis of Iterative Detection Aided Coded Modulation Schemes
No full textThe iterative convergence of iteratively detected coded modulation schemes having different block lengths, decoding complexity and an unequal error protection capability is studied, when communicating over AWGNchannels using 8PSK modulation. More specifically, the coded modulation schemes investigated include Multilevel Coding (MLC), Trellis Coded Modulation (TCM), Turbo Trellis Coded Modulation (TTCM), Bit-Interleaved Coded Modulation (BICM) as well as Bit-Interleaved Coded Modulation employing Iterative Decoding (BICM-ID). A novel three dimensional EXIT chart was introduced for studying the iterative convergence behaviour of the Multistage Decoding (MSD) scheme used in MLC
Joint design of twin-antenna assisted space-time multilevel sphere packing aided coded modulation
No full textA new multilevel coding (MLC) scheme invoking sphere packing (SP) modulation is proposed, where the SP arrangement is jointly designed with a space time block code (STBC) for the sake of attaining an additional space diversity gain. An iterative multistage decoding (MSD) aided multilevel sphere packing demodulator is proposed for attaining a high decoding performance at a low decoding complexity, when communicating over a correlated Rayleigh channel. The appropriate design of a 4-dimensional (4D) sphere packing bit-to-SP-symbol mapping scheme and the beneficial choice of the individual coding rates of the MLC scheme allows us to provide an unequal error protection capability, which is often required for efficient audio or video transmissions
Multilevel Generalised Low-Density Parity-Check Codes
No full textMultilevel coding invoking generalised low-density parity-check component codes is proposed, which is capable of outperforming the classic low-density parity check component codes at a reduced decoding latency
Generalized Low-Density Parity-Check Coding Aided Multilevel Codes
No full textClassic Low-Density Parity-Check (LDPC) codes have recently been used as component codes in Multilevel Coding (MLC) due to their impressive BER performance as well as owing to their flexible coding rates. In this paper, we proposed a Multilevel Coding invoking Generalized Low-Density Parity-Check (GLDPC) component codes, which is capable of outperforming the classic LDPC component codes at a reduced decoding latency, when communicating over AWGN and uncorrelated Rayleigh fading channels
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