Several space-time coding based transmit diversity techniques for wideband code division multiple access (WCDMA) systems with four transmitter antennas are investigated. Performances of the rake receivers are analyzed...Several space-time coding based transmit diversity techniques for wideband code division multiple access (WCDMA) systems with four transmitter antennas are investigated. Performances of the rake receivers are analyzed and compared with those of the multi-antenna receive diversity techniques. Theoretical analysis shows that the multi-antenna transmit diversity techniques provide considerable performance gain at the mobile receiver in the wireless channel with less inherent multipath diversity, especially the G4 coding based scheme. Compared with the multi-antenna receive diversity techniques with the same diversity order, the transmit diversity techniques introduce much more multi-access plus multipath interference and require measures of interference suppression in the multi-user environments.展开更多
In this paper,a two-way relay system which achieves bi-directional communication via a multiple-antenna relay in two time slots is studied.In the multiple access(MA) phase,the novel receive schemes based on Dempster-S...In this paper,a two-way relay system which achieves bi-directional communication via a multiple-antenna relay in two time slots is studied.In the multiple access(MA) phase,the novel receive schemes based on Dempster-Shafer(D-S) evidence theory are proposed at the relay node.Instead of traditional linear detection,the first proposed MIMO-DS NC scheme adopts D-S evidence theory to detect the signals of each source node before mapping them into network-coded signal.Moreover,different from traditional physical-layer network coding(PNC) based on virtual MIMO model,the further proposed MIMO-DS PNC comes from the vector space perspective and combines PNC mapping with D-S theory to obtain network-coded signal without estimating each source node signal.D-S theory can appropriately characterize uncertainty and make full use of multiple evidence source information by Dempster's combination rule to obtain reliable decisions.In the broadcast(BC) phase,the space-time coding(STC) and antenna selection(AS) schemes are adopted to achieve transmit diversity.Simulation results reveal that the STC and AS schemes both achieve full transmit diversity in the BC phase and the proposed MIMO-DS NC/PNC schemes obtain better end-to-end BER performance and throughputs compared with traditional schemes with a little complexity increasing and no matter which scheme is adopted in the BC phase,MIMO-DS PNC always achieves full end-to-end diversity gain as MIMO-ML NC but with a lower complexity and its throughput approaches the throughput of MIMO-ML NC in high SNR regime.展开更多
This paper represents a comparative performance evaluation of different diversity combining techniques for a SIMO-OFDM （single-input-multiple-output orthogonal frequency division multiplexing） system over Rayleigh f...This paper represents a comparative performance evaluation of different diversity combining techniques for a SIMO-OFDM （single-input-multiple-output orthogonal frequency division multiplexing） system over Rayleigh fading channel. OFDM is a key technique for achieving high data rates and spectral efficiency requirements for wireless communication systems. But in scattering environment, the system performances are severely degraded by the effects of multipath fading and inter-symbol interference. In wireless communication systems, antenna diversity is an important technique to combat multipath fading in order to improve the system performance and increase the channel capacity. In this paper, the performance of different diversity combining techniques-SC （selection combining）, EGC （equal gain combining） and MRC （maximal ratio combining） has been analyzed and compared in terms of SNR （signal to noise ratio） and BER （bit error rate） probability. The simulation results show that the maximal ratio combining technique provides maximum performance improvement relative to all other combining schemes by maximizing the SNR of SIMO-OFDM system at the combiner output. The analytic expressions of error probability and effective bit energy to noise ratio correlated with BPSK （binary phase shift keying） modulation have been derived and formulated for N-branch SC, EGC and MRC schemes. The BER characteristics for all three combining techniques are simulated in MATLAB （matrix laboratory） tool box for varying bit energy to noise ratio. Our results also derives that SNR can be improved if the number of receiving antenna is increased, which in turn reduces BER over a Rayleigh fading channel.展开更多
基金TheNationalNaturalScienceFoundationofChina (No .60 3 90 5 40 ) .
文摘Several space-time coding based transmit diversity techniques for wideband code division multiple access (WCDMA) systems with four transmitter antennas are investigated. Performances of the rake receivers are analyzed and compared with those of the multi-antenna receive diversity techniques. Theoretical analysis shows that the multi-antenna transmit diversity techniques provide considerable performance gain at the mobile receiver in the wireless channel with less inherent multipath diversity, especially the G4 coding based scheme. Compared with the multi-antenna receive diversity techniques with the same diversity order, the transmit diversity techniques introduce much more multi-access plus multipath interference and require measures of interference suppression in the multi-user environments.
基金jointly supported by the National Natural Science Foundation of China under Grant 61201198 and 61372089the Beijing Natural Science Foundation under Grant 4132015,4132007and 4132019
文摘In this paper,a two-way relay system which achieves bi-directional communication via a multiple-antenna relay in two time slots is studied.In the multiple access(MA) phase,the novel receive schemes based on Dempster-Shafer(D-S) evidence theory are proposed at the relay node.Instead of traditional linear detection,the first proposed MIMO-DS NC scheme adopts D-S evidence theory to detect the signals of each source node before mapping them into network-coded signal.Moreover,different from traditional physical-layer network coding(PNC) based on virtual MIMO model,the further proposed MIMO-DS PNC comes from the vector space perspective and combines PNC mapping with D-S theory to obtain network-coded signal without estimating each source node signal.D-S theory can appropriately characterize uncertainty and make full use of multiple evidence source information by Dempster's combination rule to obtain reliable decisions.In the broadcast(BC) phase,the space-time coding(STC) and antenna selection(AS) schemes are adopted to achieve transmit diversity.Simulation results reveal that the STC and AS schemes both achieve full transmit diversity in the BC phase and the proposed MIMO-DS NC/PNC schemes obtain better end-to-end BER performance and throughputs compared with traditional schemes with a little complexity increasing and no matter which scheme is adopted in the BC phase,MIMO-DS PNC always achieves full end-to-end diversity gain as MIMO-ML NC but with a lower complexity and its throughput approaches the throughput of MIMO-ML NC in high SNR regime.
文摘This paper represents a comparative performance evaluation of different diversity combining techniques for a SIMO-OFDM （single-input-multiple-output orthogonal frequency division multiplexing） system over Rayleigh fading channel. OFDM is a key technique for achieving high data rates and spectral efficiency requirements for wireless communication systems. But in scattering environment, the system performances are severely degraded by the effects of multipath fading and inter-symbol interference. In wireless communication systems, antenna diversity is an important technique to combat multipath fading in order to improve the system performance and increase the channel capacity. In this paper, the performance of different diversity combining techniques-SC （selection combining）, EGC （equal gain combining） and MRC （maximal ratio combining） has been analyzed and compared in terms of SNR （signal to noise ratio） and BER （bit error rate） probability. The simulation results show that the maximal ratio combining technique provides maximum performance improvement relative to all other combining schemes by maximizing the SNR of SIMO-OFDM system at the combiner output. The analytic expressions of error probability and effective bit energy to noise ratio correlated with BPSK （binary phase shift keying） modulation have been derived and formulated for N-branch SC, EGC and MRC schemes. The BER characteristics for all three combining techniques are simulated in MATLAB （matrix laboratory） tool box for varying bit energy to noise ratio. Our results also derives that SNR can be improved if the number of receiving antenna is increased, which in turn reduces BER over a Rayleigh fading channel.
