Intermediate codes have been shown to facilitate iterative decoding convergence to the maximum-likelihood (ML) error ratio performance in serially concatenated schemes. In this paper, we propose a novel block-based in...
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Intermediate codes have been shown to facilitate iterative decoding convergence to the maximum-likelihood (ML) error ratio performance in serially concatenated schemes. In this paper, we propose a novel block-based intermediate code as an alternative to classic convolutional intermediate codes. Because it is block-based, our intermediate code facilitates practical implementations with reduced memory and processing requirements. Furthermore, we demonstrate that it is simpler to analyze and optimize the iterative decoding process when our block-based intermediate code is employed, instead of a convolutional intermediate code. Finally, we demonstrate that the proposed block-based intermediate code facilitates significantly reduced error ratios in practical schemes when employing short transmission frames and a limited decoding complexity.
In bit-interleaved coded modulation with iterative decoding (BICM-ID), the extrinsic information transfer (EXIT) function of the demapper can be parameterised. Using this parameterisation, in conjunction with the EXIT...
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In bit-interleaved coded modulation with iterative decoding (BICM-ID), the extrinsic information transfer (EXIT) function of the demapper can be parameterised. Using this parameterisation, in conjunction with the EXIT function of the decoder, a symbol mapping design criterion based on the flatness of the gap between the two EXIT functions (called the maximum flatness criterion) is proposed in this study. Simulation results confirm that a good performance can be achieved in terms of convergence rate for fast fading channels and outage probability for slow fading channels.
This paper explores the modulation bandwidth limits for switching amplifiers, by analyzing the fundamental tracking capabilities of two-level switching signals. With this aim, this work synthesizes two-level switching...
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This paper explores the modulation bandwidth limits for switching amplifiers, by analyzing the fundamental tracking capabilities of two-level switching signals. With this aim, this work synthesizes two-level switching signals by obtaining the distribution of switching events providing both minimum average switching frequency and inband-error-free encoding, targeting to minimize the amplifier switching losses when tracking a generic bandlimited signal. This analysis also provides a framework reference to characterize the deviation from such limit in modulations used in actual amplifiers.
A novel joint adaptive modulation scheme for the broadcast phase of a two-way relay channel is presented. Over Rayleigh flat fading channels, by jointly encoding and modulating the messages from both users according t...
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A novel joint adaptive modulation scheme for the broadcast phase of a two-way relay channel is presented. Over Rayleigh flat fading channels, by jointly encoding and modulating the messages from both users according to each user's instantaneous channel quality, the relay can greatly improve its bits-per-symbol throughput during the broadcast phase. Also, each user can receive at the data rate decided by its instantaneous channel quality under the target average bit error ratio constraint by interference cancellation using its own information. Computer simulation shows the proposed scheme provides about 3 dB gain over the network coding based adaptive modulation scheme.
We propose an iterative decoding scheme for holographic data storage that uses modulation codes with a trellis structure to obtain some coding gain. Furthermore, the iterative scheme between a channel detector and the...
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We propose an iterative decoding scheme for holographic data storage that uses modulation codes with a trellis structure to obtain some coding gain. Furthermore, the iterative scheme between a channel detector and the modulation code can achieve more coding gain. In the simulation, when there are (10%, 10%) and (20%, 20%) misalignments, the proposed iterative scheme with a pseudorandom interleaver performs approximately 0.3 and 1 dB better, respectively, compared to the scheme without iteration. (C) 2011 The Japan Society of Applied Physics
Novel hybrid symbols for parallel free space optical and radio frequency links using bit-interleaved coded modulation with iterative detection are proposed. An asymptotic bit error performance analysis for the propose...
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Novel hybrid symbols for parallel free space optical and radio frequency links using bit-interleaved coded modulation with iterative detection are proposed. An asymptotic bit error performance analysis for the proposed hybrid symbols is developed. The proposed symbol mapping achieves gains of several dBs over conventional mappings.
It is a big challenge to design an effective scheduling algorithm for multimedia transmissions over a wireless channel that employs adaptive modulation and coding (AMC). On one hand, the scheduling algorithm needs to ...
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It is a big challenge to design an effective scheduling algorithm for multimedia transmissions over a wireless channel that employs adaptive modulation and coding (AMC). On one hand, the scheduling algorithm needs to schedule user transmissions by taking advantages of the channel diversity so that the overall system performance can be improved. On the other hand, the algorithm also needs to maintain fairness among users and to provide QoS guarantee based on user requirements. In this paper, we propose a novel scheduling algorithm called QoS-based cross-layer scheduling algorithm (QoS-CLS) to address the aforementioned issues. To maximize the system throughput, the algorithm takes into consideration both the physical layer and data link layer information to schedule user transmissions. Using the cross-layer information, the scheduling problem is formulated into a Markov decision process (MDP) and the optimum decision policy (based on the channel status, traffic state and buffer status of each traffic flow) is precalculated by linear programming and stored in the system for scheduling in real-time. Results show that QoS-CLS can greatly enhance the channel throughput compared to the opportunistic scheduling algorithm because of its cross-layer QoS consideration and the optimization method. Moreover, it can provide QoS guarantee and facilitate resource sharing among different traffic flows.
Erlang capacity is traditionally defined as the maximum value of offered traffic among different service classes that the system can support when the blocking probabilities at the call admission control (CAC) level do...
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Erlang capacity is traditionally defined as the maximum value of offered traffic among different service classes that the system can support when the blocking probabilities at the call admission control (CAC) level do not exceed certain thresholds. That is valid when a fixed amount of bandwidth is allocated to each user in each frame during the whole service time. However, with the introduction of adaptive modulation and coding (AMC) scheme employed at the physical layer, outage might occur due to the fact that the allocation of bandwidth is dynamic based on the time-varying wireless channel conditions. In this paper, we evaluate the Erlang capacity of a TDMA system with AMC supporting voice and data traffics, by taking both the blocking and the outage probabilities into account. The analytical models for calculating the blocking and the outage probabilities are developed separately, and a joint algorithm for determining the Erlang capacity of the system is proposed with some numerical examples.
Adaptive modulation and coding is a commonly used technique to improve throughput in wireless system. Due to the delay in channel condition feedbacks, the actual channel condition may change at the time of transmissio...
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Adaptive modulation and coding is a commonly used technique to improve throughput in wireless system. Due to the delay in channel condition feedbacks, the actual channel condition may change at the time of transmission and results in capacity loss. In this paper, we establish a model to analyze the capacity loss due to channel condition feedback delay. Simulation results show that our approach is more accurate to calculate the capacity loss, compared to traditional K-step Markov approach. The results can be used to design channel update frequency adaptive to channel conditions and diversity reception.
The system model and the algorithm for a cross-layer design combining the adaptive modulation and coding with ARQ based on frequency domain subcarrier of OFDM is developed at first. And then the effect of high speed m...
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The system model and the algorithm for a cross-layer design combining the adaptive modulation and coding with ARQ based on frequency domain subcarrier of OFDM is developed at first. And then the effect of high speed move to the performance of that is analyzed. In order to compensate the degraded performance of wireless link due to high-speed move, a novel finite-state Markov channel model is formed to represent the frequency domain subcarrier of OFDM modeled as random process with Nakagami-m fading distribution. A correction of the threshold of modulation and coding scheme and the channel quality information as well as the method for link prediction in Chase combining is investigated. On this foundation, an improved cross-layer design combining of adaptive modulation and coding with H-ARQ is proposed. The computer simulation results reveal that the improved design and modified algorithm has higher average throughput and lower FER than the original one when the terminal moves in high speed.
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