1,720,986 research outputs found
Robust Transmission of H.264 Coded Video Using Three-Stage Iterative Joint Source and Channel Decoding
No full textIn this paper we considered jointly optimised source and channel decoding, while employing serially concatenated and iteratively decoded Short Block Codes (SBC) combined with a Unity Rate Code (URC) and multi-dimensional Sphere Packing (SP) modulation. The resultant coded signal is transmitted over non-coherently detected Multiple-Input Multiple-Output (MIMO) Differential Space-Time Spreading (DSTS) designed for near capacity joint source-channel decoding (JSCD). The performance of the system was evaluated by considering interactive video telephony using the H.264/AVC source codec. The source coded parameters generated by the state-of-the-art H.264/AVC video codec typically contain limited natural residual redundancy. Therefore, to improve the error robustness of iterative sourcechannel decoding (ISCD), SBCs are incorporated to impose artificial redundancy on the source coded parameters. The natural residual redundancy after source coding and the artificial redundancy due to SBC coding is iteratively exploited in a turbo process to improve the overall Bit Error Ratio (BER) and objective video quality performance quantified in terms of the Peak Signal to Noise Ratio (PSNR). The convergence behaviour of the advocated MIMO transceiver is investigated with the aid of Extrinsic Information Transfer (EXIT) charts. The proposed system exhibits an E/sub b//N/sub 0/ gain of about 22 dB at the PSNR degradation point of 2 dB in comparison to the benchmarker scheme carrying out DSTS aided SP-demodulation as well as iterative source and channel decoding, when using I/sub system/ = 5 system iterations, while communicating over correlated narrowband Rayleigh fading channels
Near-Instantaneously Adaptive Cooperative Schemes based on Space-Time Block Codes and V-BLAST
No full textIn this paper we propose two adaptive schemes for improving the achievable throughput of cooperative diversity aided wireless networks. These schemes are capable of accommodating the channel signal-to-noise ratio (SNR) variation of wireless systems by near-instantaneously adapting the uplink transmission configuration. Explicitly, the first adaptive transmission scheme is constituted by a novel reconfigurable multilayered space-time block code (MLSTBC) structure. By contrast, the second adaptive scheme is constituted by a reconfigurable vertical Bell Labs Layered Space Time (VBLAST)-like architecture. Our results demonstrate that significant effective throughput improvements can be achieved by both systems, while maintaining a target bit-error-ratio of 10-3. Explicitly, the first system is capable of attaining an effective throughput varying between 1 bit-per-symbol (BPS) and 8 BPS, while the second has a throughput varying between 2 BPS and 8 BPS
Layered Steered Space-Time Codes and their capacity
No full textA capacity analysis of a multifunctional multiple-input multiple-output system that combines the benefits of vertical Bell Labs space-time scheme, space-time block codes and beamforming is presented
Differential Space-Time Spreading using Iteratively Detected Sphere Packing Modulation and Two Transmit Antennas
No full textA novel Differentially encoded Space-Time Spreading (DSTS) scheme using two transmit antennas and Sphere Packing (SP) is proposed, which we refer to as the DSTS-SP arrangement. The advocated SP-aided system outperforms DSTS dispensing with SP and requires no channel knowledge. We also demonstrate that the performance of DSTS-SP systems can be further improved by serially concatenated convolutional coding and by performing SP-symbol-to-bit demapping as well as channel decoding iteratively. Explicitly, the proposed turbo-detected DSTS-SP scheme exhibits an Eb/N0 gain of 17.8dB at a Bit Error Rate (BER) of 10?5 over an uncoded identical-throughput system and an Eb/N0 gain of 1.9dB over the equivalent 2 bits/symbol effective throughput QPSK-modulated turbo-detected DSTS scheme
Differential Space-Time Spreading using Four Transmit Antennas and Iteratively Detected Sphere Packing Modulation
Full text linkThis paper presents a novel Differentially encoded Space-Time Spreading (DSTS) scheme using four transmit antennas that can be readily combined with PSK, QAM, as well as Sphere Packing (SP) modulation schemes. The advocated SP-aided system has simple encoding and decoding algorithms that requires no channel knowledge and outperforms the DSTS dispensing with SP. Further improvement to the system performance can be obtained by serially concatenated convolutional coding and then performing SP-symbol-to-bit demapping as well as channel decoding iteratively. Explicitly, the proposed turbo-detected DSTS-SP scheme exhibits an Eb/N0 gain of 18dB at a Bit Error Rate (BER) of 10-5 over an uncoded identical-throughput system and an Eb/N0 gain of 2dB over an equivalent 1 bits/symbol effective throughput QPSK-modulated turbo-detected DSTS scheme dispensing with SP
Layered Steered Space-Time Codes Using Iterative Detection
No full textThis paper presents a novel multifunctional multiple-input multiple-output (MIMO) scheme that combines the benefits of the Vertical Bell Labs Layered Space-Time (VBLAST) scheme, of Space-Time Codes (STC) as well as of beamforming. Further system performance improvements can be attained by serially concatenated convolutional encoding combined with a unity-rate code (URC) referred to as a precoder. Then, at the receiver side, iterative decoding is invoked by exchanging extrinsic information between the precoder’s decoder as well as the outer Recursive Systematic Convolutional (RSC) code’s decoder. Moreover, the convergence behaviour of the proposed system is evaluated with the aid of 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 1 dB from the maximum achievable rate
Adaptive Differential Space-Time-Spreading-Assisted Turbo-Detected Sphere Packing Modulation
Full text linkIn this contribution a novel adaptive differential space-time spreading assisted turbo detected sphere packingmodulation scheme is proposed for improving the achievable throughput of code division multiple access (CDMA) systems. The scheme is capable of accommodating the channel signal-to-noise ratio (SNR) variation of wireless systems by adapting the system parameters. Explicitly, an adaptive transmission scheme constituted by a novel reconfigurable four transmit antenna aided arrangement using a variable spreading factor based differential space-time spreading scheme, as well as variable code rate recursive systematic convolutional codes is introduced. Our results demonstrate that significant effective throughput improvement can be achieved while maintaining a target bit-error-ratio of 10-4. Explicitly, when assuming an ideal Nyquist filter having a zero excess bandwidth, the system’s effective throughput varies from 0.25 bits/sec/Hz to 16 bits/sec/Hz
Hybrid beamforming design for dual-polarised millimetre wave MIMO systems
No full textMillimetre wave (mmWave) communications provide a favourable solution to the ever-increasing data rate demands because of their abundant bandwidth availability. The conventional wisdom about the mmWave communication channel is that it always exhibits line-of-sight (LOS) propagation with directive antennas. However, in mobile communications, mmWave frequencies suffer from frequent LOS blockages and exhibit multipath propagation, which motivates the study and analysis of the polarimetric properties of the mmWave channel. While the exploitation of polarisation is promising, the cross-polarisation associated with it can be detrimental to the overall performance. Therefore, in this Letter, the authors propose a hybrid precoder design, which mitigates the cross-polarisation by the joint design of a radio-frequency beamformer as well as the precoder and combiner used in the baseband. The authors demonstrate through simulations that the proposed design outperforms eigen-beamforming by 10 dB at a given rate, when considering polarisation.</p
Over-Complete Mapping Aided, Soft-Bit Assisted Iterative Unequal Error Protection H.264 Joint Source and Channel Decoding
No full textJoint-alphabet space time shift keying in mm-wave non-orthogonal multiple access
No full textFlexible modulation schemes and smart multiple-input multiple-output techniques, as well as low-complexity detectors and preprocessors may become essential for efficiently balancing the bit error ratio performance, throughput, and complexity tradeoff for various application scenarios. Millimeter-Wave systems have a high available bandwidth and the potential to accommodate numerous antennas in a small area, which makes them an attractive candidate for future networks employing spatial modulation and spacetime shift keying (STSK). Non-Orthogonal Multiple Access (NOMA) systems are capable of achieving an increased throughput, by allowing multiple users to share the same resources at the cost of a higher transmission power, or an increased detection (preprocessing) complexity at the receiver (transmitter) of an uplink (downlink) scenario. In this paper, we propose the new concept of joint-alphabet space time shift keying. As an application scenario, we employ it in the context of the uplink of NOMA mm-Wave systems. We demonstrate with the aid of extrinsic information transfer charts that a higher capacity is achievable when compared with STSK, while retaining the attractive flexibility of STSK in terms of its diversity gain and coding rate. Finally, we conceive quantum-assisted detectors for reducing the detection complexity, while attaining a near-optimal performance, when compared with the optimal iterative maximum A posteriori probability detector
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