Joint Angular and Time Diversity of Multi-Antenna CDMA Systems in Wireless Fading Channels

2011 ◽  
Vol 1 (1) ◽  
pp. 1-14
Author(s):  
Feng She ◽  
Hsiao Hwa Chen ◽  
Hongyang Li
Keyword(s):  
Fading Channels ◽  
Performance Improvement ◽  
Multipath Fading ◽  
Antenna System ◽  
Space Time ◽  
Diversity Gain ◽  
Multipath Fading Channel ◽  
Time Diversity ◽  
Time Domains ◽  
Code Division Multiple

In this paper, a multi-antenna based receiver structure for direct sequence code division multiple access (DS/CDMA) system is proposed. The proposed scheme exploits the excellent time resolution of a CDMA RAKE receiver and uses an antenna array beamforming structure to resolve multipath returns in both angular and time domains. A much higher diversity gain than that based only on the time domain diversity can be achieved. This work suggests a new space-time diversity paradigm, namely angular-time diversity, which differs from traditional Alamouti-type space-time coded schemes. The impairments caused by multipath and multiuser interference are analyzed. The performance of the proposed receiver in multipath fading channel is explicitly evaluated. An expression for uncoded system bit error probability is derived. Simulation results show the performance improvement in terms of BER due to the use of multi-antenna in the receiver, and the results illustrate that the multi-antenna based receiver works effectively in resolving multipaths in both angular and time domains to achieve performance improvement due to angular and time diversity gain provided by the multi-antenna system.

Joint Angular and Time Diversity of Multi-Antenna CDMA Systems in Wireless Fading Channels

2013 ◽  
pp. 1-14
Author(s):  
Feng She ◽  
Hsiao Hwa Chen ◽  
Hongyang Li
Keyword(s):  
Fading Channels ◽  
Performance Improvement ◽  
Antenna System ◽  
Space Time ◽  
Diversity Gain ◽  
Multipath Fading Channel ◽  
Time Diversity ◽  
Time Domains ◽  
The Time Domain ◽  
Array Beamforming

In this paper, a multi-antenna based receiver structure for direct sequence code division multiple access (DS/CDMA) system is proposed. The proposed scheme exploits the excellent time resolution of a CDMA RAKE receiver and uses an antenna array beamforming structure to resolve multipath returns in both angular and time domains. A much higher diversity gain than that based only on the time domain diversity can be achieved. This work suggests a new space-time diversity paradigm, namely angular-time diversity, which differs from traditional Alamouti-type space-time coded schemes. The impairments caused by multipath and multiuser interference are analyzed. The performance of the proposed receiver in multipath fading channel is explicitly evaluated. An expression for uncoded system bit error probability is derived. Simulation results show the performance improvement in terms of BER due to the use of multi-antenna in the receiver, and the results illustrate that the multi-antenna based receiver works effectively in resolving multipaths in both angular and time domains to achieve performance improvement due to angular and time diversity gain provided by the multi-antenna system.

ROBUST JPEG2000 IMAGE TRANSMISSION THROUGH LOW SNR MULTI-CARRIER CDMA SYSTEM IN FREQUENCY-SELECTIVE RAYLEIGH FADING CHANNELS: A PERFORMANCE STUDY

2011 ◽  
Vol 09 (02) ◽  
pp. 283-303 ◽  
Author(s):  
KATHIYAIAH THIYAGU ◽  
T. H. OH
Keyword(s):  
Fading Channels ◽  
Signal To Noise Ratio ◽  
Image Transmission ◽  
Multipath Fading ◽  
Cdma System ◽  
Performance Study ◽  
Compression Technique ◽  
Multipath Fading Channel ◽  
Low Snr ◽  
Code Division Multiple

The demand for high data rate transmission is ever increasing every day. Multi-carrier code division multiple access (MC-CDMA) system is considered as the forerunner and advancement in the mobile communication system. In this paper, two types of JPEG2000 lossily-compressed test images are transmitted through an MC-CDMA channel in low SNR (as low as 4 dB) environment and their quality are evaluated objectively by using peak signal-to-noise ratio (PSNR) and root mean square error (RMSE). The test images are all compressed from ratio of 10 : 1 up to 70 : 1 and the system involves multi-user image transmission in near real-time low SNR (±5 dB). It is found that JPEG2000 image compression technique that applies wavelet transform performed quite well in the low SNR multipath fading channel — as low as 4 dB, and this looks promising for future applications.

scholarly journals Simple Channel Estimation Techniques Based on Pilot-Assistance for STBC-Based MIMO-OFDM Systems

2009 ◽  
Author(s):  
Tran Duc Tan ◽  
Ta Duc Tuyen ◽  
Trinh Anh Vu ◽  
Huynh Huu Tue
Keyword(s):  
Channel Estimation ◽  
Fading Channels ◽  
Performance Improvement ◽  
Additive Noise ◽  
Multipath Fading ◽  
Ofdm Systems ◽  
Multipath Fading Channels ◽  
Pilot Assistance ◽  
Mimo Ofdm ◽  
High Flexibility

With equipping multiple antennas at both transmitter and receiver ends, the signals in the wireless OFDM systems could be transmitted over multipath fading channels for achieving benefits and high flexibility. In this paper, we focus on MIMO-OFDM systems that simultaneously perform channel estimation in order to combat additive noise, and multipath fading. The performance improvement is confirmed by simulations. Results show that the proposed MIMOOFDM scheme is quite robust in practical environments.

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