In this paper, the structure of a trellis-coded 3-dimensional orthogonal frequency division multiplexing (3-D OFDM) is proposed and its error performance in additive white Gaussian channel is analyzed. We present the ...
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In this paper, the structure of a trellis-coded 3-dimensional orthogonal frequency division multiplexing (3-D OFDM) is proposed and its error performance in additive white Gaussian channel is analyzed. We present the set-partitioning of a 3-D 8-ary constellation for trellis coding. As a result, the trellis-coded 3-D OFDM system has around 6 dB coding gain over an uncoded one when an 8-ary constellation is exploited. And it also has around 3 dB better symbol error probability as compared to the uncoded system when a 4-ary constellation is employed. Thus, the proposed trellis-coded 3-D OFDM may be appropriate for an application in the high-quality wireless communication system for the next generation.
Angle Quantization Index modulation (AQIM) is a watermarking technique that achieves provably good capacity-distortion-robustness performance. The scheme embeds each bit of a watermark message on an image by quantizin...
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Angle Quantization Index modulation (AQIM) is a watermarking technique that achieves provably good capacity-distortion-robustness performance. The scheme embeds each bit of a watermark message on an image by quantizing the angle formed by a vector of pixels or frequency coefficients from the host image with the origin of a hyperspherical coordinate system. While it has been demonstrated that AQIM is insensitive to intensity scaling attacks, the quantization step employed throughout the embedding process is set to a constant value regardless of the nature of the image. Because of this, the perceptual quality of the watermarked image cannot be regulated. In this paper, we propose a straightforward yet powerful AQIM-based watermarking scheme that considers the statistical behavior of the region where a message bit is to be embedded before settling on the size of the quantization step. Experimental results show that, for the same watermark capacity and image fidelity parameters, our proposed region-specific scheme exhibits a lower bit error rate than the regular AQIM approach.
In this paper, we investigate power allocation strategies for an orthogonal frequency division multiplexing (OFDM) cooperative network over frequency-selective fading channels. Assuming amplify-and-forward relaying, w...
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In this paper, we investigate power allocation strategies for an orthogonal frequency division multiplexing (OFDM) cooperative network over frequency-selective fading channels. Assuming amplify-and-forward relaying, we propose a power loading algorithm to minimize the bit error rate under total transmission power constraint for a given data rate. We consider both uncoded ODFM and OFDM encoupled with bit-interleaved coded modulation. Our Monte Carlo simulation study demonstrates significant performance gains through power loading. The impact of several practical issues on the error rate performance such as imperfect channel estimation and limited feedback is further investigated.
We present a new class of reduced-complexity high-performance iterative receivers for single-user MIMO/OFDM systems with bit-interleaved coded modulation (BICM). The proposed inner-outer decoder structures rely on joi...
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We present a new class of reduced-complexity high-performance iterative receivers for single-user MIMO/OFDM systems with bit-interleaved coded modulation (BICM). The proposed inner-outer decoder structures rely on joint demappers which generate soft-output via an M-algorithm limited tree-search. A key element of the proposed designs is the way the M-algorithm chooses its survivor candidates during the tree search. In particular, at every depth in the tree the survivor list comprises the best M candidates as well as additional good candidates which are chosen to enable high-quality soft-output information for every bit. In the context of iterative inner/outer decoders, simulations show that the proposed survivor selection criteria result in superior performance/complexity trade-offs as compared to a conventional M-algorithm search.
Rate adaptation based on signal-to-noise ratio (SNR) measurements is a common channel adaptation scheme to increase throughput in wireless communication systems. To use rate adaptation efficiently in cooperative wirel...
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Rate adaptation based on signal-to-noise ratio (SNR) measurements is a common channel adaptation scheme to increase throughput in wireless communication systems. To use rate adaptation efficiently in cooperative wireless networks, an adaptation algorithm must consider multiple channels (source- destination, source-relays, and relays-destination) to select modulation and code rates that maximize throughput. In this paper we analyze the potential gains that combining cooperation with rate adaptation brings in three steps: (1) We derive the theoretical capacity bounds for ideal rate adaptation schemes for typical topologies. (2) We propose an offline heuristic for computing SNR thresholds aimed at reaching the derived bounds. (3) Using this heuristic, we compare rate adaptation for maximal ratio combining (MRC), where links are equally adapted, with soft-bit MRC (SBMRC), where links are individually adapted. We find that adapting the rate per link is superior in terms of throughput.
Link layer abstraction is crucial both the cross layer simulation and design and the interface to complete a system level simulator. The calibration takes an important role within this design. In this paper we have us...
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Link layer abstraction is crucial both the cross layer simulation and design and the interface to complete a system level simulator. The calibration takes an important role within this design. In this paper we have used several kinds of algorithms like EESM, CESM and LESM for the instantaneous channel, calibration and evaluation of the link level interface in WiMAX system 802.16e. In order to have real world situations, we are also using the adaptative modulation and coding (AMC), hybrid automatic repeat request (H-ARQ) and PUSC/FUSC permutation besides of OFDM systems. Plenty of simulations were made for evaluate the different algorithms and the results show that EESM has better accuracy that the others.
To prolong the lifetime of nodes in wireless sensor networks, both transmission cost and processing power should be minimized. For this purpose, we propose a new direct source channel mapping method which utilizes lar...
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To prolong the lifetime of nodes in wireless sensor networks, both transmission cost and processing power should be minimized. For this purpose, we propose a new direct source channel mapping method which utilizes large bandwidth. The system combines a closed-loop Differential Pulse Code modulation (DPCM) source coder followed by pulse position modulation (PPM) transmission. To accommodate closed-loop prediction over a noisy channel an additional feedback channel is used. Two or more sequential samples are predicted at a time and combined before transmission, thus reducing transmission cost further. Simulations performed on both an auto regressive AR(1) source and a test image over additive white Gaussian noise (AWGN) channel show that our proposed system can achieve significant energy saving for both noiseless and noisy feedback channels without delay.
In radio resource management of multimedia broadcast/multicast service (MBMS), user equipment (UE) feedback can be used by evolved Node B (eNB) to improve the radio spectral efficiency. As UE feedback is costly we her...
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In radio resource management of multimedia broadcast/multicast service (MBMS), user equipment (UE) feedback can be used by evolved Node B (eNB) to improve the radio spectral efficiency. As UE feedback is costly we here suggest schemes to reduce the uplink feedback while maintaining the spectral efficiency. For the 3 schemes analyzed in this paper we utilize the special characteristic of a broadcast channel, that spectral efficiency is mainly determined by the UE with lowest channel quality. The performance of the suggested schemes are evaluated with long term evolution (LTE) system simulation and we conclude that using geometry for selecting feedback UEs is the optimal solution and 4 feedback UEs are enough to meet the coverage requirement.
We investigate the error exponent of exclusive-or multiple-access channels (XMAC) where the receiver wants to reconstruct the exclusive-or of incoming messages from two transmitters. We consider both the multiple acce...
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ISBN:
(纸本)9781424443123
We investigate the error exponent of exclusive-or multiple-access channels (XMAC) where the receiver wants to reconstruct the exclusive-or of incoming messages from two transmitters. We consider both the multiple access channel (MAC) strategy and the network coding (NC) strategy. In our analysis, the cutoff rate is used as a performance measure. Assuming a Gaussian XMAC and binary phase-shift keying (BPSK) modulation at each node, we show that the MAC strategy performs better than the NC strategy in the low rate region while the NC strategy performs better in the high rate region.
This paper presents a novel multi-functional MultipleInput Multiple-Output (MIMO) scheme that combines the benefits of the Vertical Bell Labs Layered Space-Time (V-BLAST) scheme, of SpaceTime Codes (STC) as well as of...
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This paper presents a novel multi-functional MultipleInput Multiple-Output (MIMO) scheme that combines the benefits of the Vertical Bell Labs Layered Space-Time (V-BLAST) scheme, of SpaceTime Codes (STC) as well as of beamforming. To further enhance the attainable system performance and to maximise the coding advantage of the proposed transmission scheme, the system is also combined with multi-dimensional Sphere Packing (SP) modulation. Additionally, further system performance improvements can be attained by serially concatenated convolutional coding combined with a Unity-Rate Code (URC) employed as an inner code. Then, at the receiver side, iterative decoding is invoked by exchanging extrinsic information between the three constituent decoders, i.e. the outer convolutional code's decoder, the inner URC's decoder as well as the SP demapper. Moreover, the convergence behaviour of the proposed scheme is evaluated with the aid of both three-dimensional (3D) and two-dimensional (2D) Extrinsic Information Transfer (EXIT) charts. Finally, we quantify the maximum achievable rate of the system based on EXIT charts and demonstrate that the iterative-detection-aided system is capable of operating within 0.6 dB from the maximum achievable rate limit. Explicitly, the proposed iteratively detected three-stage LSSTC-SP scheme is capable of attaining at least 4.8 dB gain at a BER of 10 -5 over the conventional iterativedetection aided two-stage scheme, where the extrinsic information is limited to the SP demapper and the outer code's decoder.
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