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Papers by antonis phasouliotis
VTC Spring 2009 - IEEE 69th Vehicular Technology Conference, 2009
In this paper, we analyze and compare the error rate performance of downlink coded multiple-input... more In this paper, we analyze and compare the error rate performance of downlink coded multiple-input multiple-output multi-carrier code division multiple access (MIMO MC-CDMA) and coded MIMO orthogonal frequency division multiple access (MIMO OFDMA) systems under frequency selective fading channel conditions. In particular, the pairwise error probabilities (PEP) for both systems are derived. Simulation results illustrate that when the number of users, hence the system load is low, MIMO MC-CDMA outperforms MIMO OFDMA. However when the system load increases, the performance of MIMO MC-CDMA deteriorates and becomes worse than MIMO OFDMA. This can be explained by the PEP analysis of MIMO MC-CDMA which shows that when the number of users is small, the multiuser interference is also small and frequency diversity is better exploited. Conversely at high system load, MIMO OFDMA outperforms MIMO MC-CDMA as it is insensitive to multiuser interference. Nevertheless if the other users' spreading sequences are available at the receiver of the desired user, the impact of multiuser interference can be minimised and MIMO MC-CDMA outperforms MIMO OFDMA at all system loads.
2010 IEEE 72nd Vehicular Technology Conference - Fall, 2010
In this paper, we propose user grouping algorithms to provide power minimization in grouped MC-CD... more In this paper, we propose user grouping algorithms to provide power minimization in grouped MC-CDMA systems. Depending on the channel fading conditions, power control is utilized to minimize the total transmitted power under a bit error rate (BER) constraint. When the allocation is performed without a fair data rate requirement, we provide the optimal solution to the minimization problem. However
VTC Spring 2008 - IEEE Vehicular Technology Conference, 2008
In this paper, a chip level ordered successive spatial and multiuser interference cancellation (O... more In this paper, a chip level ordered successive spatial and multiuser interference cancellation (OSSMIC) receiver architecture is presented for downlink multiple-input multipleoutput multi-carrier code division multiple access (MIMO MC-CDMA) systems. The proposed receiver performs ordered layer space-time detection. Unlike the existing ordered successive interference cancellation (OSIC) receiver, the proposed receiver cancels both spatial & multiuser interference in the SIC process. This allows detection in multiuser scenario, which is not possible in conventional chip level OSIC receiver. Simulation results show that the proposed receiver significantly outperforms both the existing chip level OSIC detector and the chip level linear receiver. As the proposed receiver only requires the knowledge of the desired user's spreading sequence, it is a viable solution for downlink MIMO MC-CDMA communications.
IET Communications, 2011
Energy efficiency has become increasingly important in wireless communications nowadays. Saving e... more Energy efficiency has become increasingly important in wireless communications nowadays. Saving energy will not only reduce operating cost but also reduces greenhouse gas emissions, which is important for combating climate change. The authors propose energy-efficient user grouping algorithms to provide power minimisation of grouped multi-carrier code division multiple access (MC-CDMA) and space-time block coding MC-CDMA systems in a cellular environment. Depending on the channel fading conditions, power control is utilised to minimise the total transmitted power under a bit error rate constraint. When the allocation is performed without a fair data rate requirement, the authors provide the optimal solution to the minimisation problem. However, when some fairness is considered, the optimal solution requires high computational complexity. Thus, the authors solve the problem by proposing two suboptimal algorithms. Simulation results illustrate a significantly reduced power consumption in comparison with other techniques.
IET Communications, 2011
Multi-carrier code division multiple access (MC-CDMA) allows multiuser communication with frequen... more Multi-carrier code division multiple access (MC-CDMA) allows multiuser communication with frequency diversity. To increase the system data rates, spatial multiplexing for multiple-input multiple-output (MIMO) MC-CDMA has been investigated. This study proposes a chip level layered space-time (LST) receiver architecture for coded downlink MIMO MC-CDMA systems. As the conventional chip level ordered successive interference cancellation (OSIC) receiver is unable to overcome multiple access interference and performs poorly in multiuser scenarios, the proposed receiver cancels both spatial and multiuser interference in an ordered LST detection process by requiring only the knowledge of the desired user's spreading sequence. Simulation results show that the proposed receiver not only performs better than the existing linear detectors but also outperforms both the chip and symbol level OSIC receivers. In this study the authors also compare the error rate performance between the proposed system and MIMO orthogonal frequency division multiple access (MIMO OFDMA) system and they justify the comparisons by deriving and analysing the pairwise error probability (PEP) for both systems. MIMO MC-CDMA demonstrates a better performance over MIMO OFDMA under low system load. If all users' spreading sequences are known, multiuser interference can be reduced and MIMO MC-CDMA performs better than MIMO OFDMA at all system loads.
VTC Spring 2009 - IEEE 69th Vehicular Technology Conference, 2009
In this paper, we analyze and compare the error rate performance of downlink coded multiple-input... more In this paper, we analyze and compare the error rate performance of downlink coded multiple-input multiple-output multi-carrier code division multiple access (MIMO MC-CDMA) and coded MIMO orthogonal frequency division multiple access (MIMO OFDMA) systems under frequency selective fading channel conditions. In particular, the pairwise error probabilities (PEP) for both systems are derived. Simulation results illustrate that when the number of users, hence the system load is low, MIMO MC-CDMA outperforms MIMO OFDMA. However when the system load increases, the performance of MIMO MC-CDMA deteriorates and becomes worse than MIMO OFDMA. This can be explained by the PEP analysis of MIMO MC-CDMA which shows that when the number of users is small, the multiuser interference is also small and frequency diversity is better exploited. Conversely at high system load, MIMO OFDMA outperforms MIMO MC-CDMA as it is insensitive to multiuser interference. Nevertheless if the other users' spreading sequences are available at the receiver of the desired user, the impact of multiuser interference can be minimised and MIMO MC-CDMA outperforms MIMO OFDMA at all system loads.
2010 IEEE 72nd Vehicular Technology Conference - Fall, 2010
In this paper, we propose user grouping algorithms to provide power minimization in grouped MC-CD... more In this paper, we propose user grouping algorithms to provide power minimization in grouped MC-CDMA systems. Depending on the channel fading conditions, power control is utilized to minimize the total transmitted power under a bit error rate (BER) constraint. When the allocation is performed without a fair data rate requirement, we provide the optimal solution to the minimization problem. However
VTC Spring 2008 - IEEE Vehicular Technology Conference, 2008
In this paper, a chip level ordered successive spatial and multiuser interference cancellation (O... more In this paper, a chip level ordered successive spatial and multiuser interference cancellation (OSSMIC) receiver architecture is presented for downlink multiple-input multipleoutput multi-carrier code division multiple access (MIMO MC-CDMA) systems. The proposed receiver performs ordered layer space-time detection. Unlike the existing ordered successive interference cancellation (OSIC) receiver, the proposed receiver cancels both spatial & multiuser interference in the SIC process. This allows detection in multiuser scenario, which is not possible in conventional chip level OSIC receiver. Simulation results show that the proposed receiver significantly outperforms both the existing chip level OSIC detector and the chip level linear receiver. As the proposed receiver only requires the knowledge of the desired user's spreading sequence, it is a viable solution for downlink MIMO MC-CDMA communications.
IET Communications, 2011
Energy efficiency has become increasingly important in wireless communications nowadays. Saving e... more Energy efficiency has become increasingly important in wireless communications nowadays. Saving energy will not only reduce operating cost but also reduces greenhouse gas emissions, which is important for combating climate change. The authors propose energy-efficient user grouping algorithms to provide power minimisation of grouped multi-carrier code division multiple access (MC-CDMA) and space-time block coding MC-CDMA systems in a cellular environment. Depending on the channel fading conditions, power control is utilised to minimise the total transmitted power under a bit error rate constraint. When the allocation is performed without a fair data rate requirement, the authors provide the optimal solution to the minimisation problem. However, when some fairness is considered, the optimal solution requires high computational complexity. Thus, the authors solve the problem by proposing two suboptimal algorithms. Simulation results illustrate a significantly reduced power consumption in comparison with other techniques.
IET Communications, 2011
Multi-carrier code division multiple access (MC-CDMA) allows multiuser communication with frequen... more Multi-carrier code division multiple access (MC-CDMA) allows multiuser communication with frequency diversity. To increase the system data rates, spatial multiplexing for multiple-input multiple-output (MIMO) MC-CDMA has been investigated. This study proposes a chip level layered space-time (LST) receiver architecture for coded downlink MIMO MC-CDMA systems. As the conventional chip level ordered successive interference cancellation (OSIC) receiver is unable to overcome multiple access interference and performs poorly in multiuser scenarios, the proposed receiver cancels both spatial and multiuser interference in an ordered LST detection process by requiring only the knowledge of the desired user's spreading sequence. Simulation results show that the proposed receiver not only performs better than the existing linear detectors but also outperforms both the chip and symbol level OSIC receivers. In this study the authors also compare the error rate performance between the proposed system and MIMO orthogonal frequency division multiple access (MIMO OFDMA) system and they justify the comparisons by deriving and analysing the pairwise error probability (PEP) for both systems. MIMO MC-CDMA demonstrates a better performance over MIMO OFDMA under low system load. If all users' spreading sequences are known, multiuser interference can be reduced and MIMO MC-CDMA performs better than MIMO OFDMA at all system loads.