Soon Ng - Academia.edu (original) (raw)
Papers by Soon Ng
Reproductive Medicine and Biology, 2005
Aim Ovarian hyperstimulation syndrome (OHSS) is a potentially life-threatening, iatrogenic compl... more Aim Ovarian hyperstimulation syndrome (OHSS) is a potentially life-threatening, iatrogenic complication of assisted reproduction and has been associated with poor in vitro fertilization outcome. The aim of the present study was to evaluate the pregnancy rate and outcome following severe OHSS, at a single center over a three-year period. Methods The incidence of severe OHSS at the IVF Center, National University of
Journal of Obstetrics and Gynaecology Research, 2007
Ectopic pregnancy is conventionally managed by laparoscopic salpingectomy. Electrocautery has bee... more Ectopic pregnancy is conventionally managed by laparoscopic salpingectomy. Electrocautery has been used widely to secure hemostasis during salpingectomy. However, this method is associated with a risk of thermal injury to the visceral organs. Endoloop, a pre-tied suture used in laparoscopic surgery may be an alternative treatment tool and its potential use in the management of ectopic pregnancy is explored here. Our study aims to compare the effectiveness of the endoloop technique to electrocautery during laparoscopic salpingectomy for tubal pregnancy. A prospective randomized controlled study was conducted over 24 months at the Hospital Universiti Kebangsaan Malaysia. One hundred and two patients with tubal pregnancy were randomized into two treatment groups: those treated with endoloop and those treated with electrocautery during laparoscopic salpingectomy. The use of an endoloop was associated with a shorter operating time (48.85 min +/- 21.019 vs 61.14 min +/- 22.603, 95% CI -20.864 to -3.724), lower visual analog scores for postoperative pain at day 1 (2.02 +/- 0.960 vs 2.74 +/- 0.828, 95% CI -1.074 to -0.368) and day 7 (0.85 +/- 0.802 vs 1.44 +/- 0.837, 95% CI -0.916 to -0.272), and lesser total analgesia required by patients at day 7 after the operation (7.65 +/- 6.119 vs 15.32 +/- 8.326, 95% CI -10.529 to -4.804). There was no significant difference in the ability to secure hemostasis when both techniques were compared. Duration of hospitalization (2.37 days +/- 0.817 vs 2.34 days +/- 0.519, 95% CI -0.245 to -0.296) and interval from operation to discharge were similar. The endoloop appeared to be as effective as electrocautery and is a safe alternative to electrocautery for laparoscopic salpingectomy in tubal pregnancy.
International Journal of Gynecology & Obstetrics, 1994
IEEE Vehicular Technology Magazine, 2012
ABSTRACT In this article, we propose a cooperative space-time coding (STC) protocol, amalgamating... more ABSTRACT In this article, we propose a cooperative space-time coding (STC) protocol, amalgamating the concepts of asynchronous cooperation, noncoherent detection, as well as distributed turbo coding (DTC), where neither symbol-level time synchronization nor channel-state information (CSI) estimation is required at any of the cooperating nodes, while attaining high performance even at low signal-to-noise ratios (SNRs). More specifically assuming the system configuration of a single source node, multiple relay nodes, and a single destination node, each having a single antenna element (AE)a practical cooperative differential space-time spreading (CDSTS) scheme is designed using interference rejection spreading codes, to eliminate the effect of synchronization errors between the relay nodes without the assistance of channel estimation or equalization.
2010 International Conference on Computational Intelligence and Software Engineering, 2010
In this contribution we study a range of turbo-coded cooperative diversity schemes in the context... more In this contribution we study a range of turbo-coded cooperative diversity schemes in the context of a Code Division Multiple Access (CDMA) system. The cooperative diversity architectures considered are the Amplify-and-Forward (AF), Decode-and-Forward (DF) and Soft Relay (SR) schemes. We derived the soft-decision metric for the turbo decoder based on the Minimum Mean Square Error (MMSE) detection when considering the
2007 IEEE 66th Vehicular Technology Conference, 2007
Bit-Interleaved Coded Modulation using Iterative Decoding (BICM-ID) is amalgamated with Luby Tran... more Bit-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.
Annals of the Academy of Medicine, Singapore, 2008
2005 IEEE 61st Vehicular Technology Conference, 2005
A full-rate, full-diversity Adaptive Space Time Block Coding (ASTBC) scheme based on Singular Val... more A full-rate, full-diversity Adaptive Space Time Block Coding (ASTBC) scheme based on Singular Value Decomposition (SVD) is proposed for transmission over Rayleigh fading channels. The ASTBC-SVD scheme advocated is capable of providing both full-rate and full-diversity for any number of transmit antennas, N t , provided that the number of receive antennas, N r , equals to N t . Furthermore, the ASTBC-SVD scheme may achieve an additional coding gain due to its higher product distance with the aid of the block code employed. In conjunction with SVD, the "water-filling" approach can be employed for adaptively distributing the transmitted power to the various antennas transmit according to the channel conditions, in order to further enhance the attainable performance. Since a codeword constituted by N t symbols is transmitted in a single time slot by mapping the N t symbols to the N t transmit antennas in the spatial domain, the attainable performance of the ASTBC-SVD scheme does not degrade, when the channel impulse response values vary from one time slot to the next. Hence, the proposed ASTBC-SVD scheme is attractive in the context of both uncorrelated and correlated Rayleigh fading channels. The performance of the proposed scheme was evaluated, when communicating over uncorrelated Rayleigh fading channels. Explicitly, an E b /N 0 gain of 2.5 dB was achieved by the proposed ASTBC-SVD scheme against Alamouti's scheme [1], when employing N t = N r = 2 in conjunction with 8PSK.
IEEE GLOBECOM 2008 - 2008 IEEE Global Telecommunications Conference, 2008
In this treatise Extrinsic Information Transfer (EXIT) charts are used to design binary Self-Conc... more In this treatise Extrinsic Information Transfer (EXIT) charts are used to design binary Self-Concatenated Convolutional Codes employing Iterative Decoding (SECCC-ID) for communicating over both uncorrelated Rayleigh fading and Additive White Gaussian Noise (AWGN) channels. Recursive Systematic Convolutional (RSC) codes are selected as constituent codes, an interleaver is used for randomising the extrinsic information exchange of the constituent codes, while a puncturer assists us in increasing the achievable bandwidth efficiency. At the receiver, self-iterative decoding is invoked for exchanging extrinsic information between the hypothetical decoder components. The convergence behaviour of the decoder is analysed with the aid of bit-based EXIT charts. Finally, we propose an attractive system configuration, which is capable of operating within about 1 dB of the information-theoretic limits.
Procedia Computer Science, 2014
In this contribution, a novel network coding (NC) aided multi-input multi-output (MIMO) scheme is... more In this contribution, a novel network coding (NC) aided multi-input multi-output (MIMO) scheme is proposed for providing reliable transmission from an ambulance assisting in an emergency situation by cooperating with relaying devices at an emergency scene. Our system is constituted by an Irregular Convolutional Coded Unity Rate Coded Space Time Trellis Coded M-ary Phase Shift Keying (IrCC-URC-STTC-MPSK) scheme invoked for exploiting the benefits of MIMO systems. The system is designed with the aid of Extrinsic Information Transfer (EXIT) charts for approaching the corresponding channel capacity in fast fading environments. The proposed scheme exhibits substantial benefits over conventional MIMO systems in hostile wireless channels.
IET Communications, 2013
The active cooperation between a primary user (PU) and a cognitive user (CU) has the potential of... more The active cooperation between a primary user (PU) and a cognitive user (CU) has the potential of leading to a transmission power reduction and transmission rate increase for both the PU and the CU. Alternatively, the required bandwidth may be reduced and the freed bandwidth may be leased to a group of CUs for their secondary communications. More explicitly, our cooperative protocol allows a CU to serve as a relay node (RN) for relaying the signal of the first PU, which is a source node (SN), to the second PU, which is a destination node (DN). Furthermore, we conceived adaptive turbo trellis coded modulation (ATTCM) for appropriately adjusting both the code rate and the modulation mode according I to the near-instantaneous channel conditions. More specifically, we propose an ATTCM aided two-way relaying cooperative CR scheme that maximises the CU's own data rate and improves the exploitation of the bandwidth released by the PUs. Our numerical and simulation results show that the bandwidth reduction attained by the proposed two-way relay based CR scheme is more than 80% of the PU's bandwidth.
IEEE Transactions on Wireless Communications, 2000
An Iteratively Decoded Variable Length Space Time Coded Modulation (VL-STCM-ID) scheme capable of... more An Iteratively Decoded Variable Length Space Time Coded Modulation (VL-STCM-ID) scheme capable of simultaneously providing both coding and iteration gain as well as multiplexing and diversity gain is proposed. Nonbinary unity-rate precoders are employed for assisting the iterative decoding of the VL-STCM-ID scheme. The discretevalued source symbols are first encoded into variable-length codewords that are mapped to the spatial and temporal domains. Then the variable-length codewords are interleaved and fed to the precoded modulator. More explicitly, the proposed VL-STCM-ID arrangement is a jointly designed iteratively decoded scheme contriving source coding, channel coding, modulation and spatial diversity/multiplexing. As expected, the higher the source correlation, the higher the achievable performance gain of the scheme becomes. Furthermore, the performance of the VL-STCM-ID scheme is more than 14 dB better than that of the Fixed Length STCM (FL-STCM) benchmarker at a source symbol error ratio of 10 −4 .
IEEE Transactions on Wireless Communications, 2000
In this paper we propose a novel Irregular Variable Length Coding (IrVLC) scheme for near-capacit... more In this paper we propose a novel Irregular Variable Length Coding (IrVLC) scheme for near-capacity joint source and channel coding. We employ a number of component Variable Length Coding (VLC) codebooks having different coding rates for encoding particular fractions of the input source symbol stream. These fractions may be chosen with the aid of EXtrinsic Information Transfer (EXIT) charts in order to shape the inverted EXIT curve of the IrVLC codec for ensuring that it does not cross the EXIT curve of a serially concatenated channel codec. In this way, an open EXIT chart tunnel may be created even at low E b /N0 values that are close to the capacity bound of the channel. We propose iteratively decoded serially concatenated IrVLC designs amalgamated with Trellis Coded Modulation (TCM). These schemes are shown to be capable of operating within 0.6 dB of the uncorrelated narrowband Rayleigh fading channel's capacity bound using an average interleaver length of 217,500 bits and an effective bandwidth efficiency of 1.56 bit/s/Hz, assuming ideal Nyquist filtering. By contrast, the equivalentrate regular VLC-based bench-marker schemes were found to be capable of operating at a higher distance of 1.1 dB from the capacity bound, which is nearly twice that of the proposed IrVLC-TCM scheme. Additionally, an Irregular Convolutional Coding (IrCC) based bench-marker was found to be capable of operating at 0.8 dB from the capacity bound, owing to its slightly eroded performance when operating with the considered interleaver length.
IEEE Transactions on Wireless Communications, 2000
A joint video and channel coded system employing an iteratively decoded serial concatenation of a... more A joint video and channel coded system employing an iteratively decoded serial concatenation of a Vector Quantization (VQ) based video codec and a Trellis-Coded Modulation (TCM) scheme is proposed. The video codec imposes VQ-induced code constraints, which may be completely described by a trellis structure, which is employed as the basis for optimal minimum mean-squared-error VQ-encoding and -decoding. In the latter case, the Bahl-Cocke-Jelinek-Raviv (BCJR) algorithm is employed to facilitate the iterative exchange of soft information between the VQ and TCM decoder. An error-free video reconstruction quality is supported using 16-level Quadrature Amplitude Modulation (16QAM) based TCM for transmission over Rayleigh-fading channels at a Signal-to-Noise Ratio (SNR) per bit of 5.25 dB. This value is within 1.29 dB of the Rayleigh channel's capacity at our system's effective bandwidth-efficiency of 2 bits/s/Hz. Owing to its ability to exploit the VQ-induced code constraints during iterative decoding, the joint video and channel coding approach is found to consistently outperform the Shannonian source and channel separation philosophy. This is achieved at the cost of a 1.6 times higher computational complexity. Finally, the convergence of the iterative decoder is investigated with the aid of a novel so-called EXtrinsic Information Transfer (EXIT) chart.
IEEE Transactions on Wireless Communications, 2000
This paper presents a novel turbo-detected multidimensional Sphere Packing (SP) modulation scheme... more This paper presents a novel turbo-detected multidimensional Sphere Packing (SP) modulation scheme using four transmit antennas combined with Differentially encoded Space-Time Spreading (DSTS). The DSTS scheme can be readily combined with PSK, QAM as well as SP modulation schemes. The SP-aided DSTS system advocated has low-complexity encoding and decoding algorithms that require no channel knowledge and it is capable of outperforming the DSTS system dispensing with sphere packing. 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. Explicitly, the turbo-detected precoded DSTS-SP system performs within 1.6 dB of the achievable multiple-input multiple output (MIMO) capacity. Finally, in contrast to an equivalent 0.5 bit/symbol throughput turbodetected DSTS-SP scheme using no precoding, the turbo-detected precoded DSTS-SP scheme exhibits no error floor.
IEEE Transactions on Vehicular Technology, 2000
A serially concatenated and iteratively decoded Irregular Variable Length Coding (IrVLC) scheme i... more A serially concatenated and iteratively decoded Irregular Variable Length Coding (IrVLC) scheme is amalgamated with a unity-rate precoded Time-Hopping (TH) Pulse Position Modulation (PPM) aided Ultra-Wide Bandwidth (UWB) Spread-Spectrum (SS) impulse radio design. The proposed design is capable of operating at low Signal-to-Noise Ratios (SNR) in Nakagami-m fading channels contaminated by Partial Band Noise Jamming (PBNJ) as a benefit of lossless IrVLC joint source and channel coding. Although this scheme may be readily used for lossless video or audio compression for example, we only used it here for lossless near-capacity data transmission. A number of component Variable Length Coding (VLC) codebooks having different coding rates are utilized by the IrVLC scheme for encoding specific fractions of the input source symbol stream. EXtrinsic Information Transfer (EXIT) charts are used to appropriately select these fractions in order to shape the inverted EXIT curve of the IrVLC and hence to match that of the inner decoder, which allows us to achieve an infinitesimally low Bit Error Ratio (BER) at near-capacity SNR values.
IEEE Transactions on Vehicular Technology, 2000
Based on extrinsic information transfer (EXIT) charts, the convergence behavior of a three-stage ... more Based on extrinsic information transfer (EXIT) charts, the convergence behavior of a three-stage serially concatenated multiuser beamforming receiver is presented. This system uses a linear minimum bit error rate (BER) multiuser detector as the inner module. Due to the nonrecursive nature of this inner module, a unity-rate memory-1 recursive precoder is placed in front of the channel to provide the required recursive structure. Irregular convolutional codes (IRCCs) are constructed to be used as the outer code to achieve near-capacity performance. Our simulations show that this system outperforms the traditional two-component iterative structure and is capable of significantly reducing the error floor.
IEEE Transactions on Vehicular Technology, 2000
In this paper, we propose a power-efficient distributed binary self-concatenated coding scheme us... more In this paper, we propose a power-efficient distributed binary self-concatenated coding scheme using iterative decoding (DSECCC-ID) for cooperative communications. The DSECCC-ID scheme is designed with the aid of binary extrinsic information transfer (EXIT) charts. The source node transmits self-concatenated convolutional coded (SECCC) symbols to both the relay and destination nodes during the first transmission period. The relay performs SECCC-ID decoding, where it may or may not encounter decoding errors. It then reencodes the information bits using a recursive systematic convolutional (RSC) code during the second transmission period. The resultant symbols transmitted from the source and relay nodes can be viewed as the coded symbols of a three-component parallel concatenated encoder. At the destination node, three-component DSECCC-ID decoding is performed. The EXIT chart gives us an insight into operation of the distributed coding scheme, which enables us to significantly reduce the transmit power by about 3.3 dB in signal-to-noise ratio (SNR) terms, as compared with a noncooperative SECCC-ID scheme at a bit error rate (BER) of 10 −5 . Finally, the proposed system is capable of performing within about 1.5 dB from the two-hop relay-aided network's capacity at a BER of 10 −5 , even if there may be decoding errors at the relay.
IEEE Transactions on Vehicular Technology, 2000
A novel space-time block-coding-assisted and sphere-packed multilevel-coded (STBC-SP-MLC) modulat... more A novel space-time block-coding-assisted and sphere-packed multilevel-coded (STBC-SP-MLC) modulation arrangement is proposed, which combines an MLC-based scheme with a twin-antenna-aided STBC for the sake of providing a transmit diversity gain. The SP modulation invokes a 4-D D 4 constellation space. A new bit-to-SP symbol mapper is designed for the sake of improving the system's performance. This involves mapping the MLC bits to the SP symbols of Layer-1 and Layer-2 in D 4 space. The Binary Switching Algorithm is used to determine the optimum cost function used for designing different mapping strategies. The so-called equivalent capacity-based design invoking the 4-D signal space is used to determine the optimum coding rate of the STBC-SP-MLC scheme's component codes. Finally, we investigate a hybrid bit-to-SP symbol-mapping strategy for the STBC-SP-MLC scheme, which is capable of providing unequal error protection.
IEEE Transactions on Vehicular Technology, 2000
A recently proposed space-time block-coding (STBC) signal construction method that combines ortho... more A recently proposed space-time block-coding (STBC) signal construction method that combines orthogonal design with sphere packing (SP) (referred to here as STBC-SP) has shown useful performance improvements over Alamouti's conventional orthogonal design. In this paper, we propose a purely symbol-based, low-density parity-check (LDPC)-coded scheme, demonstrating that the performance of STBC-SP systems can further be improved by concatenating SP-aided modulation with nonbinary LDPC and by performing symbol-based turbo detection between the nonbinary LDPC decoder and a rate-1 nonbinary inner precoder. We also investigate the convergence behavior of this symbol-based concatenated scheme with the aid of novel nonbinary extrinsic information transfer (EXIT) charts. Finally, we demonstrate that in the investigated scenarios, it requires 1-2 dB lower power in comparison with the equivalent effectivethroughput 0.5-, 0.75-, and 1-bit/symbol systems employing bit-based turbo detection.
Reproductive Medicine and Biology, 2005
Aim Ovarian hyperstimulation syndrome (OHSS) is a potentially life-threatening, iatrogenic compl... more Aim Ovarian hyperstimulation syndrome (OHSS) is a potentially life-threatening, iatrogenic complication of assisted reproduction and has been associated with poor in vitro fertilization outcome. The aim of the present study was to evaluate the pregnancy rate and outcome following severe OHSS, at a single center over a three-year period. Methods The incidence of severe OHSS at the IVF Center, National University of
Journal of Obstetrics and Gynaecology Research, 2007
Ectopic pregnancy is conventionally managed by laparoscopic salpingectomy. Electrocautery has bee... more Ectopic pregnancy is conventionally managed by laparoscopic salpingectomy. Electrocautery has been used widely to secure hemostasis during salpingectomy. However, this method is associated with a risk of thermal injury to the visceral organs. Endoloop, a pre-tied suture used in laparoscopic surgery may be an alternative treatment tool and its potential use in the management of ectopic pregnancy is explored here. Our study aims to compare the effectiveness of the endoloop technique to electrocautery during laparoscopic salpingectomy for tubal pregnancy. A prospective randomized controlled study was conducted over 24 months at the Hospital Universiti Kebangsaan Malaysia. One hundred and two patients with tubal pregnancy were randomized into two treatment groups: those treated with endoloop and those treated with electrocautery during laparoscopic salpingectomy. The use of an endoloop was associated with a shorter operating time (48.85 min +/- 21.019 vs 61.14 min +/- 22.603, 95% CI -20.864 to -3.724), lower visual analog scores for postoperative pain at day 1 (2.02 +/- 0.960 vs 2.74 +/- 0.828, 95% CI -1.074 to -0.368) and day 7 (0.85 +/- 0.802 vs 1.44 +/- 0.837, 95% CI -0.916 to -0.272), and lesser total analgesia required by patients at day 7 after the operation (7.65 +/- 6.119 vs 15.32 +/- 8.326, 95% CI -10.529 to -4.804). There was no significant difference in the ability to secure hemostasis when both techniques were compared. Duration of hospitalization (2.37 days +/- 0.817 vs 2.34 days +/- 0.519, 95% CI -0.245 to -0.296) and interval from operation to discharge were similar. The endoloop appeared to be as effective as electrocautery and is a safe alternative to electrocautery for laparoscopic salpingectomy in tubal pregnancy.
International Journal of Gynecology & Obstetrics, 1994
IEEE Vehicular Technology Magazine, 2012
ABSTRACT In this article, we propose a cooperative space-time coding (STC) protocol, amalgamating... more ABSTRACT In this article, we propose a cooperative space-time coding (STC) protocol, amalgamating the concepts of asynchronous cooperation, noncoherent detection, as well as distributed turbo coding (DTC), where neither symbol-level time synchronization nor channel-state information (CSI) estimation is required at any of the cooperating nodes, while attaining high performance even at low signal-to-noise ratios (SNRs). More specifically assuming the system configuration of a single source node, multiple relay nodes, and a single destination node, each having a single antenna element (AE)a practical cooperative differential space-time spreading (CDSTS) scheme is designed using interference rejection spreading codes, to eliminate the effect of synchronization errors between the relay nodes without the assistance of channel estimation or equalization.
2010 International Conference on Computational Intelligence and Software Engineering, 2010
In this contribution we study a range of turbo-coded cooperative diversity schemes in the context... more In this contribution we study a range of turbo-coded cooperative diversity schemes in the context of a Code Division Multiple Access (CDMA) system. The cooperative diversity architectures considered are the Amplify-and-Forward (AF), Decode-and-Forward (DF) and Soft Relay (SR) schemes. We derived the soft-decision metric for the turbo decoder based on the Minimum Mean Square Error (MMSE) detection when considering the
2007 IEEE 66th Vehicular Technology Conference, 2007
Bit-Interleaved Coded Modulation using Iterative Decoding (BICM-ID) is amalgamated with Luby Tran... more Bit-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.
Annals of the Academy of Medicine, Singapore, 2008
2005 IEEE 61st Vehicular Technology Conference, 2005
A full-rate, full-diversity Adaptive Space Time Block Coding (ASTBC) scheme based on Singular Val... more A full-rate, full-diversity Adaptive Space Time Block Coding (ASTBC) scheme based on Singular Value Decomposition (SVD) is proposed for transmission over Rayleigh fading channels. The ASTBC-SVD scheme advocated is capable of providing both full-rate and full-diversity for any number of transmit antennas, N t , provided that the number of receive antennas, N r , equals to N t . Furthermore, the ASTBC-SVD scheme may achieve an additional coding gain due to its higher product distance with the aid of the block code employed. In conjunction with SVD, the "water-filling" approach can be employed for adaptively distributing the transmitted power to the various antennas transmit according to the channel conditions, in order to further enhance the attainable performance. Since a codeword constituted by N t symbols is transmitted in a single time slot by mapping the N t symbols to the N t transmit antennas in the spatial domain, the attainable performance of the ASTBC-SVD scheme does not degrade, when the channel impulse response values vary from one time slot to the next. Hence, the proposed ASTBC-SVD scheme is attractive in the context of both uncorrelated and correlated Rayleigh fading channels. The performance of the proposed scheme was evaluated, when communicating over uncorrelated Rayleigh fading channels. Explicitly, an E b /N 0 gain of 2.5 dB was achieved by the proposed ASTBC-SVD scheme against Alamouti's scheme [1], when employing N t = N r = 2 in conjunction with 8PSK.
IEEE GLOBECOM 2008 - 2008 IEEE Global Telecommunications Conference, 2008
In this treatise Extrinsic Information Transfer (EXIT) charts are used to design binary Self-Conc... more In this treatise Extrinsic Information Transfer (EXIT) charts are used to design binary Self-Concatenated Convolutional Codes employing Iterative Decoding (SECCC-ID) for communicating over both uncorrelated Rayleigh fading and Additive White Gaussian Noise (AWGN) channels. Recursive Systematic Convolutional (RSC) codes are selected as constituent codes, an interleaver is used for randomising the extrinsic information exchange of the constituent codes, while a puncturer assists us in increasing the achievable bandwidth efficiency. At the receiver, self-iterative decoding is invoked for exchanging extrinsic information between the hypothetical decoder components. The convergence behaviour of the decoder is analysed with the aid of bit-based EXIT charts. Finally, we propose an attractive system configuration, which is capable of operating within about 1 dB of the information-theoretic limits.
Procedia Computer Science, 2014
In this contribution, a novel network coding (NC) aided multi-input multi-output (MIMO) scheme is... more In this contribution, a novel network coding (NC) aided multi-input multi-output (MIMO) scheme is proposed for providing reliable transmission from an ambulance assisting in an emergency situation by cooperating with relaying devices at an emergency scene. Our system is constituted by an Irregular Convolutional Coded Unity Rate Coded Space Time Trellis Coded M-ary Phase Shift Keying (IrCC-URC-STTC-MPSK) scheme invoked for exploiting the benefits of MIMO systems. The system is designed with the aid of Extrinsic Information Transfer (EXIT) charts for approaching the corresponding channel capacity in fast fading environments. The proposed scheme exhibits substantial benefits over conventional MIMO systems in hostile wireless channels.
IET Communications, 2013
The active cooperation between a primary user (PU) and a cognitive user (CU) has the potential of... more The active cooperation between a primary user (PU) and a cognitive user (CU) has the potential of leading to a transmission power reduction and transmission rate increase for both the PU and the CU. Alternatively, the required bandwidth may be reduced and the freed bandwidth may be leased to a group of CUs for their secondary communications. More explicitly, our cooperative protocol allows a CU to serve as a relay node (RN) for relaying the signal of the first PU, which is a source node (SN), to the second PU, which is a destination node (DN). Furthermore, we conceived adaptive turbo trellis coded modulation (ATTCM) for appropriately adjusting both the code rate and the modulation mode according I to the near-instantaneous channel conditions. More specifically, we propose an ATTCM aided two-way relaying cooperative CR scheme that maximises the CU's own data rate and improves the exploitation of the bandwidth released by the PUs. Our numerical and simulation results show that the bandwidth reduction attained by the proposed two-way relay based CR scheme is more than 80% of the PU's bandwidth.
IEEE Transactions on Wireless Communications, 2000
An Iteratively Decoded Variable Length Space Time Coded Modulation (VL-STCM-ID) scheme capable of... more An Iteratively Decoded Variable Length Space Time Coded Modulation (VL-STCM-ID) scheme capable of simultaneously providing both coding and iteration gain as well as multiplexing and diversity gain is proposed. Nonbinary unity-rate precoders are employed for assisting the iterative decoding of the VL-STCM-ID scheme. The discretevalued source symbols are first encoded into variable-length codewords that are mapped to the spatial and temporal domains. Then the variable-length codewords are interleaved and fed to the precoded modulator. More explicitly, the proposed VL-STCM-ID arrangement is a jointly designed iteratively decoded scheme contriving source coding, channel coding, modulation and spatial diversity/multiplexing. As expected, the higher the source correlation, the higher the achievable performance gain of the scheme becomes. Furthermore, the performance of the VL-STCM-ID scheme is more than 14 dB better than that of the Fixed Length STCM (FL-STCM) benchmarker at a source symbol error ratio of 10 −4 .
IEEE Transactions on Wireless Communications, 2000
In this paper we propose a novel Irregular Variable Length Coding (IrVLC) scheme for near-capacit... more In this paper we propose a novel Irregular Variable Length Coding (IrVLC) scheme for near-capacity joint source and channel coding. We employ a number of component Variable Length Coding (VLC) codebooks having different coding rates for encoding particular fractions of the input source symbol stream. These fractions may be chosen with the aid of EXtrinsic Information Transfer (EXIT) charts in order to shape the inverted EXIT curve of the IrVLC codec for ensuring that it does not cross the EXIT curve of a serially concatenated channel codec. In this way, an open EXIT chart tunnel may be created even at low E b /N0 values that are close to the capacity bound of the channel. We propose iteratively decoded serially concatenated IrVLC designs amalgamated with Trellis Coded Modulation (TCM). These schemes are shown to be capable of operating within 0.6 dB of the uncorrelated narrowband Rayleigh fading channel's capacity bound using an average interleaver length of 217,500 bits and an effective bandwidth efficiency of 1.56 bit/s/Hz, assuming ideal Nyquist filtering. By contrast, the equivalentrate regular VLC-based bench-marker schemes were found to be capable of operating at a higher distance of 1.1 dB from the capacity bound, which is nearly twice that of the proposed IrVLC-TCM scheme. Additionally, an Irregular Convolutional Coding (IrCC) based bench-marker was found to be capable of operating at 0.8 dB from the capacity bound, owing to its slightly eroded performance when operating with the considered interleaver length.
IEEE Transactions on Wireless Communications, 2000
A joint video and channel coded system employing an iteratively decoded serial concatenation of a... more A joint video and channel coded system employing an iteratively decoded serial concatenation of a Vector Quantization (VQ) based video codec and a Trellis-Coded Modulation (TCM) scheme is proposed. The video codec imposes VQ-induced code constraints, which may be completely described by a trellis structure, which is employed as the basis for optimal minimum mean-squared-error VQ-encoding and -decoding. In the latter case, the Bahl-Cocke-Jelinek-Raviv (BCJR) algorithm is employed to facilitate the iterative exchange of soft information between the VQ and TCM decoder. An error-free video reconstruction quality is supported using 16-level Quadrature Amplitude Modulation (16QAM) based TCM for transmission over Rayleigh-fading channels at a Signal-to-Noise Ratio (SNR) per bit of 5.25 dB. This value is within 1.29 dB of the Rayleigh channel's capacity at our system's effective bandwidth-efficiency of 2 bits/s/Hz. Owing to its ability to exploit the VQ-induced code constraints during iterative decoding, the joint video and channel coding approach is found to consistently outperform the Shannonian source and channel separation philosophy. This is achieved at the cost of a 1.6 times higher computational complexity. Finally, the convergence of the iterative decoder is investigated with the aid of a novel so-called EXtrinsic Information Transfer (EXIT) chart.
IEEE Transactions on Wireless Communications, 2000
This paper presents a novel turbo-detected multidimensional Sphere Packing (SP) modulation scheme... more This paper presents a novel turbo-detected multidimensional Sphere Packing (SP) modulation scheme using four transmit antennas combined with Differentially encoded Space-Time Spreading (DSTS). The DSTS scheme can be readily combined with PSK, QAM as well as SP modulation schemes. The SP-aided DSTS system advocated has low-complexity encoding and decoding algorithms that require no channel knowledge and it is capable of outperforming the DSTS system dispensing with sphere packing. 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. Explicitly, the turbo-detected precoded DSTS-SP system performs within 1.6 dB of the achievable multiple-input multiple output (MIMO) capacity. Finally, in contrast to an equivalent 0.5 bit/symbol throughput turbodetected DSTS-SP scheme using no precoding, the turbo-detected precoded DSTS-SP scheme exhibits no error floor.
IEEE Transactions on Vehicular Technology, 2000
A serially concatenated and iteratively decoded Irregular Variable Length Coding (IrVLC) scheme i... more A serially concatenated and iteratively decoded Irregular Variable Length Coding (IrVLC) scheme is amalgamated with a unity-rate precoded Time-Hopping (TH) Pulse Position Modulation (PPM) aided Ultra-Wide Bandwidth (UWB) Spread-Spectrum (SS) impulse radio design. The proposed design is capable of operating at low Signal-to-Noise Ratios (SNR) in Nakagami-m fading channels contaminated by Partial Band Noise Jamming (PBNJ) as a benefit of lossless IrVLC joint source and channel coding. Although this scheme may be readily used for lossless video or audio compression for example, we only used it here for lossless near-capacity data transmission. A number of component Variable Length Coding (VLC) codebooks having different coding rates are utilized by the IrVLC scheme for encoding specific fractions of the input source symbol stream. EXtrinsic Information Transfer (EXIT) charts are used to appropriately select these fractions in order to shape the inverted EXIT curve of the IrVLC and hence to match that of the inner decoder, which allows us to achieve an infinitesimally low Bit Error Ratio (BER) at near-capacity SNR values.
IEEE Transactions on Vehicular Technology, 2000
Based on extrinsic information transfer (EXIT) charts, the convergence behavior of a three-stage ... more Based on extrinsic information transfer (EXIT) charts, the convergence behavior of a three-stage serially concatenated multiuser beamforming receiver is presented. This system uses a linear minimum bit error rate (BER) multiuser detector as the inner module. Due to the nonrecursive nature of this inner module, a unity-rate memory-1 recursive precoder is placed in front of the channel to provide the required recursive structure. Irregular convolutional codes (IRCCs) are constructed to be used as the outer code to achieve near-capacity performance. Our simulations show that this system outperforms the traditional two-component iterative structure and is capable of significantly reducing the error floor.
IEEE Transactions on Vehicular Technology, 2000
In this paper, we propose a power-efficient distributed binary self-concatenated coding scheme us... more In this paper, we propose a power-efficient distributed binary self-concatenated coding scheme using iterative decoding (DSECCC-ID) for cooperative communications. The DSECCC-ID scheme is designed with the aid of binary extrinsic information transfer (EXIT) charts. The source node transmits self-concatenated convolutional coded (SECCC) symbols to both the relay and destination nodes during the first transmission period. The relay performs SECCC-ID decoding, where it may or may not encounter decoding errors. It then reencodes the information bits using a recursive systematic convolutional (RSC) code during the second transmission period. The resultant symbols transmitted from the source and relay nodes can be viewed as the coded symbols of a three-component parallel concatenated encoder. At the destination node, three-component DSECCC-ID decoding is performed. The EXIT chart gives us an insight into operation of the distributed coding scheme, which enables us to significantly reduce the transmit power by about 3.3 dB in signal-to-noise ratio (SNR) terms, as compared with a noncooperative SECCC-ID scheme at a bit error rate (BER) of 10 −5 . Finally, the proposed system is capable of performing within about 1.5 dB from the two-hop relay-aided network's capacity at a BER of 10 −5 , even if there may be decoding errors at the relay.
IEEE Transactions on Vehicular Technology, 2000
A novel space-time block-coding-assisted and sphere-packed multilevel-coded (STBC-SP-MLC) modulat... more A novel space-time block-coding-assisted and sphere-packed multilevel-coded (STBC-SP-MLC) modulation arrangement is proposed, which combines an MLC-based scheme with a twin-antenna-aided STBC for the sake of providing a transmit diversity gain. The SP modulation invokes a 4-D D 4 constellation space. A new bit-to-SP symbol mapper is designed for the sake of improving the system's performance. This involves mapping the MLC bits to the SP symbols of Layer-1 and Layer-2 in D 4 space. The Binary Switching Algorithm is used to determine the optimum cost function used for designing different mapping strategies. The so-called equivalent capacity-based design invoking the 4-D signal space is used to determine the optimum coding rate of the STBC-SP-MLC scheme's component codes. Finally, we investigate a hybrid bit-to-SP symbol-mapping strategy for the STBC-SP-MLC scheme, which is capable of providing unequal error protection.
IEEE Transactions on Vehicular Technology, 2000
A recently proposed space-time block-coding (STBC) signal construction method that combines ortho... more A recently proposed space-time block-coding (STBC) signal construction method that combines orthogonal design with sphere packing (SP) (referred to here as STBC-SP) has shown useful performance improvements over Alamouti's conventional orthogonal design. In this paper, we propose a purely symbol-based, low-density parity-check (LDPC)-coded scheme, demonstrating that the performance of STBC-SP systems can further be improved by concatenating SP-aided modulation with nonbinary LDPC and by performing symbol-based turbo detection between the nonbinary LDPC decoder and a rate-1 nonbinary inner precoder. We also investigate the convergence behavior of this symbol-based concatenated scheme with the aid of novel nonbinary extrinsic information transfer (EXIT) charts. Finally, we demonstrate that in the investigated scenarios, it requires 1-2 dB lower power in comparison with the equivalent effectivethroughput 0.5-, 0.75-, and 1-bit/symbol systems employing bit-based turbo detection.