In this paper, we consider the effect of impulsive noise on the performance of multicarrier code ... more In this paper, we consider the effect of impulsive noise on the performance of multicarrier code division multiple access (MC-CDMA) systems and analyze the performance by examining the MC-CDMA system model in time domain. We have discovered that conventional Walsh-code based MC-CDMA is less robust to the presence of impulsive noise than the corresponding direct sequence (DS) CDMA and multicarrier modulation based (MCM) systems. Furthermore, it is demonstrated that the performance of MC-CDMA depends strongly on the selection of the utilized spreading codes. A modified MC-CDMA structure, called MC-SI-CDMA, is proposed and investigated in impulsive noise that employs subcarrier interleaving (SI) to reduce the cross- correlation between the time-domain MC-CDMA waveforms and the impulsive noise. Computer simulation results conducted to support our analysis indicate that the proposed MC-SI- CDMA system in impulsive noise can provide a performance improvement of 2.5 dB at a bit error rate (BER) level of 10-3 compared with the DS-CDMA system.
In this paper, iterative detection is applied in the receiver for downlink of both direct sequenc... more In this paper, iterative detection is applied in the receiver for downlink of both direct sequence (DS) and multi-carrier (MC) code division multiple access (CDMA) systems in the flat Rayleigh fading channels. A joint iterative detection and phase recovery scheme is proposed. Unlike the conventional bit-interleaved coded modulation with iterative decoding (BICM-ID) structure, the proposed receiver feeds the extrinsic information from soft-input soft-output (SISO) decoder back to update both the adaptive minimum mean squared error (MMSE) correlator and phase locked-loop (PLL) instead of de-mapper. We also investigate how the second-order PLL benefits from the iterative process over the time-varying flat Rayleigh fading channel. Simulation results illustrate that the iterative process significantly improves the performance of the adaptive detector by suppressing multiple access interference (MAI). Additionally, the tracking capability of PLL is enhanced by reducing the equivalent noise power.
2009 IEEE Wireless Communications and Networking Conference, 2009
In this paper, we consider the effect of impulsive noise on the performance of multicarrier code ... more In this paper, we consider the effect of impulsive noise on the performance of multicarrier code division multiple access (MC-CDMA) systems and analyze the performance by examining the MC-CDMA system model in time domain. We have discovered that conventional Walsh-code based MC-CDMA is less robust to the presence of impulsive noise than the corresponding direct sequence (DS) CDMA and multicarrier
2011 IEEE Wireless Communications and Networking Conference, 2011
AbstractIn this paper, we consider interference cancellation (IC) schemes for uplink orthogonal ... more AbstractIn this paper, we consider interference cancellation (IC) schemes for uplink orthogonal frequency division multiple-access (OFDMA) systems with carrier frequency offsets (CFOs). To improve the detection performance without increasing the computational complexity of the ...
ABSTRACT In this paper, we develop a novel reduced-rank space-time adaptive processing (STAP) alg... more ABSTRACT In this paper, we develop a novel reduced-rank space-time adaptive processing (STAP) algorithm based on adaptive basis function approximation (ABFA) for airborne radar applications. The proposed algorithm employs the well-known framework of the side-lobe canceller (SLC) structure and consists of selected sets of basis functions that perform dimensionality reduction and an adaptive reduced-rank filter. Compared to traditional reduced-rank techniques, the proposed scheme works on an instantaneous basis, selecting the best suited set of basis functions at each instant to minimize the squared error. Furthermore, we derive stochastic gradient (SG) and recursive least squares (RLS) algorithm for efficiently implementing the proposed ABFA scheme. Simulations for a clutter-plus-jamming suppression application show that the proposed STAP algorithm outperforms the state-of-the-art reduced-rank schemes in convergence and tracking at significantly lower complexity.
ABSTRACT In this paper, we propose a novel blind CFO tracking algorithm for the OFDMA uplink syst... more ABSTRACT In this paper, we propose a novel blind CFO tracking algorithm for the OFDMA uplink systems with the generalized carrier assignment scheme (GCAS). The proposed blind CFO tracking technique is built on a low complexity grouped minimum mean squared error based multi-stage interference cancellation (G-MMSE-MIC) scheme, which feeds decisions to drive the CFO tracking. The CFO tracking is implemented by using a bank of closed-loops to track the time-varying CFOs in the decision-directed (DD) mode without pilot tones. The simulation results demonstrate that the proposed blind CFOs tracking scheme performs well in the presence of time-varying CFOs with affordable complexity.
ABSTRACT In this paper, we propose a low-complexity interference cancellation (IC) scheme for OFD... more ABSTRACT In this paper, we propose a low-complexity interference cancellation (IC) scheme for OFDMA uplink systems with CFOs. The proposed scheme employs a multi-stage structure, in which a subcarrier-grouped MMSE scheme is used in each stage. To make the proposed scheme more flexible to the tradeoff between the performance and the complexity, we generalize the subcarrier-grouped MMSE scheme and employ a novel IC strategy. The simulation results show that the proposed IC scheme outperforms other existing schemes with considerable low complexity.
2009 Conference Record of the Forty-Third Asilomar Conference on Signals, Systems and Computers, 2009
MIMO radar has received significant attention in the past five years. In this paper, we focus on ... more MIMO radar has received significant attention in the past five years. In this paper, we focus on the advantage of MIMO radars in achieving better spatial resolution by employing the colocated antennas and propose a reduced-rank knowledge-aided technique for MIMO radar space-time adaptive processing (STAP) design. The scheme is based on joint iterative optimization of knowledge-aided adaptive filters (JIOKAF) and
2008 42nd Asilomar Conference on Signals, Systems and Computers, 2008
... Joint Iterative Optimization of Adaptive Filters Rui Fa, Rodrigo C. de Lamare and Danilo Zana... more ... Joint Iterative Optimization of Adaptive Filters Rui Fa, Rodrigo C. de Lamare and Danilo Zanatta-Filho Communications Research Group, Department of Electronics, University of York, YO10 5DD, United Kingdom. ... The performance of (6) is given by PFA = exp( −β2 2 ) PD = ∫ ∞ ...
... Raymundo Ramirez Gutierrez, Li Zhang and Jaafar Elmirghani School of Electronic and Electrica... more ... Raymundo Ramirez Gutierrez, Li Zhang and Jaafar Elmirghani School of Electronic and Electrical Engineering University of Leeds Leeds, United Kingdom ... is related to the information transmitted by the antenna indices as in GSSK, the active antennae transmit M-ary phase shift ...
In this paper, we consider the effect of impulsive noise on the performance of multicarrier code ... more In this paper, we consider the effect of impulsive noise on the performance of multicarrier code division multiple access (MC-CDMA) systems and analyze the performance by examining the MC-CDMA system model in time domain. We have discovered that conventional Walsh-code based MC-CDMA is less robust to the presence of impulsive noise than the corresponding direct sequence (DS) CDMA and multicarrier modulation based (MCM) systems. Furthermore, it is demonstrated that the performance of MC-CDMA depends strongly on the selection of the utilized spreading codes. A modified MC-CDMA structure, called MC-SI-CDMA, is proposed and investigated in impulsive noise that employs subcarrier interleaving (SI) to reduce the cross- correlation between the time-domain MC-CDMA waveforms and the impulsive noise. Computer simulation results conducted to support our analysis indicate that the proposed MC-SI- CDMA system in impulsive noise can provide a performance improvement of 2.5 dB at a bit error rate (BER) level of 10-3 compared with the DS-CDMA system.
In this paper, iterative detection is applied in the receiver for downlink of both direct sequenc... more In this paper, iterative detection is applied in the receiver for downlink of both direct sequence (DS) and multi-carrier (MC) code division multiple access (CDMA) systems in the flat Rayleigh fading channels. A joint iterative detection and phase recovery scheme is proposed. Unlike the conventional bit-interleaved coded modulation with iterative decoding (BICM-ID) structure, the proposed receiver feeds the extrinsic information from soft-input soft-output (SISO) decoder back to update both the adaptive minimum mean squared error (MMSE) correlator and phase locked-loop (PLL) instead of de-mapper. We also investigate how the second-order PLL benefits from the iterative process over the time-varying flat Rayleigh fading channel. Simulation results illustrate that the iterative process significantly improves the performance of the adaptive detector by suppressing multiple access interference (MAI). Additionally, the tracking capability of PLL is enhanced by reducing the equivalent noise power.
2009 IEEE Wireless Communications and Networking Conference, 2009
In this paper, we consider the effect of impulsive noise on the performance of multicarrier code ... more In this paper, we consider the effect of impulsive noise on the performance of multicarrier code division multiple access (MC-CDMA) systems and analyze the performance by examining the MC-CDMA system model in time domain. We have discovered that conventional Walsh-code based MC-CDMA is less robust to the presence of impulsive noise than the corresponding direct sequence (DS) CDMA and multicarrier
2011 IEEE Wireless Communications and Networking Conference, 2011
AbstractIn this paper, we consider interference cancellation (IC) schemes for uplink orthogonal ... more AbstractIn this paper, we consider interference cancellation (IC) schemes for uplink orthogonal frequency division multiple-access (OFDMA) systems with carrier frequency offsets (CFOs). To improve the detection performance without increasing the computational complexity of the ...
ABSTRACT In this paper, we develop a novel reduced-rank space-time adaptive processing (STAP) alg... more ABSTRACT In this paper, we develop a novel reduced-rank space-time adaptive processing (STAP) algorithm based on adaptive basis function approximation (ABFA) for airborne radar applications. The proposed algorithm employs the well-known framework of the side-lobe canceller (SLC) structure and consists of selected sets of basis functions that perform dimensionality reduction and an adaptive reduced-rank filter. Compared to traditional reduced-rank techniques, the proposed scheme works on an instantaneous basis, selecting the best suited set of basis functions at each instant to minimize the squared error. Furthermore, we derive stochastic gradient (SG) and recursive least squares (RLS) algorithm for efficiently implementing the proposed ABFA scheme. Simulations for a clutter-plus-jamming suppression application show that the proposed STAP algorithm outperforms the state-of-the-art reduced-rank schemes in convergence and tracking at significantly lower complexity.
ABSTRACT In this paper, we propose a novel blind CFO tracking algorithm for the OFDMA uplink syst... more ABSTRACT In this paper, we propose a novel blind CFO tracking algorithm for the OFDMA uplink systems with the generalized carrier assignment scheme (GCAS). The proposed blind CFO tracking technique is built on a low complexity grouped minimum mean squared error based multi-stage interference cancellation (G-MMSE-MIC) scheme, which feeds decisions to drive the CFO tracking. The CFO tracking is implemented by using a bank of closed-loops to track the time-varying CFOs in the decision-directed (DD) mode without pilot tones. The simulation results demonstrate that the proposed blind CFOs tracking scheme performs well in the presence of time-varying CFOs with affordable complexity.
ABSTRACT In this paper, we propose a low-complexity interference cancellation (IC) scheme for OFD... more ABSTRACT In this paper, we propose a low-complexity interference cancellation (IC) scheme for OFDMA uplink systems with CFOs. The proposed scheme employs a multi-stage structure, in which a subcarrier-grouped MMSE scheme is used in each stage. To make the proposed scheme more flexible to the tradeoff between the performance and the complexity, we generalize the subcarrier-grouped MMSE scheme and employ a novel IC strategy. The simulation results show that the proposed IC scheme outperforms other existing schemes with considerable low complexity.
2009 Conference Record of the Forty-Third Asilomar Conference on Signals, Systems and Computers, 2009
MIMO radar has received significant attention in the past five years. In this paper, we focus on ... more MIMO radar has received significant attention in the past five years. In this paper, we focus on the advantage of MIMO radars in achieving better spatial resolution by employing the colocated antennas and propose a reduced-rank knowledge-aided technique for MIMO radar space-time adaptive processing (STAP) design. The scheme is based on joint iterative optimization of knowledge-aided adaptive filters (JIOKAF) and
2008 42nd Asilomar Conference on Signals, Systems and Computers, 2008
... Joint Iterative Optimization of Adaptive Filters Rui Fa, Rodrigo C. de Lamare and Danilo Zana... more ... Joint Iterative Optimization of Adaptive Filters Rui Fa, Rodrigo C. de Lamare and Danilo Zanatta-Filho Communications Research Group, Department of Electronics, University of York, YO10 5DD, United Kingdom. ... The performance of (6) is given by PFA = exp( −β2 2 ) PD = ∫ ∞ ...
... Raymundo Ramirez Gutierrez, Li Zhang and Jaafar Elmirghani School of Electronic and Electrica... more ... Raymundo Ramirez Gutierrez, Li Zhang and Jaafar Elmirghani School of Electronic and Electrical Engineering University of Leeds Leeds, United Kingdom ... is related to the information transmitted by the antenna indices as in GSSK, the active antennae transmit M-ary phase shift ...
Uploads