Analysis and Contrast Between STC and Spatial Diversity Techniques for OFDM WLAN with Channel Estimation

Abstract In this paper, we study the performance improvement of free space optical (FSO) communication system with spatial diversity techniques employing hybrid pulse position modulation-binary phase shift keying-subcarrier intensity modulation (PPM-BPSK-SIM). The involvement of multiple photo-detectors in diversity based FSO systems offers an effective way to overcome scntillation. In this paper, we have simulated the bit error rate (BER) with respect to different parameters like average SNR, link distance at various weather conditions. The simulation results are verified in Matlab environment with the mathematical analysis. The simulation results show that higher order single input multiple output (SIMO) system achieves better BER performance and hybrid PPM-BPSK-SIM has significant improved performance than the common modulation schemes like PPM, BPSK-SIM.

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Blind SOS subspace channel estimation and equalization techniques exploiting spatial diversity in OFDM systems

Digital Signal Processing ◽

10.1016/s1051-2004(03)00008-3 ◽

2004 ◽

Vol 14 (2) ◽

pp. 171-202 ◽

Cited By ~ 25

Author(s):

Hassan Ali ◽

Arnaud Doucet ◽

Yingbo Hua

Keyword(s):

Channel Estimation ◽

Spatial Diversity ◽

Ofdm Systems ◽

Subspace Channel Estimation ◽

Channel Estimation And Equalization

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Capacity of Optical Wireless System over Log-Normal Channels with Spatial Diversity in Presence of Atmospheric Losses

Journal of Optical Communications ◽

10.1515/joc-2016-0151 ◽

2018 ◽

Vol 39 (3) ◽

pp. 349-357 ◽

Cited By ~ 1

Author(s):

Rahul Kaushik ◽

Vineet Khandelwal ◽

R.C. Jain

Keyword(s):

Atmospheric Turbulence ◽

Channel Capacity ◽

Random Variable ◽

Weather Conditions ◽

Spatial Diversity ◽

Closed Form Expression ◽

Atmospheric Conditions ◽

Optical Wireless ◽

Diversity Techniques ◽

Log Normal

Abstract In this paper, average channel capacity of optical wireless communication system is evaluated under the combined effect of geometrical loss, attenuation due to weather conditions and weak atmospheric turbulence using a simple closed form expression. Fading induced due to atmospheric turbulence is modeled by log-normal distribution. Considering the fact that the sum of log-normal random variables can be well approximated by another log-normal random variable, the proposed expression has been utilized to compute the channel capacity for spatial diversity reception employing maximum ratio combining and equal gain combining over uncorrelated turbulence-induced fading conditions. It is shown that spatial diversity is an effective technique to mitigate the impairments caused by various atmospheric conditions such as haze, rain and fog. The quantitative improvement in channel capacity achieved by using diversity techniques is investigated and compared. Accuracy of the results is validated with exact results computed using Monte Carlo simulation.

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Individual Channel Estimation in a Diamond Relay Network Using Relay-Assisted Training

International Journal of Digital Multimedia Broadcasting ◽

10.1155/2017/1320689 ◽

2017 ◽

Vol 2017 ◽

pp. 1-8

Author(s):

Xianwen He ◽

Gaoqi Dou ◽

Jun Gao

Keyword(s):

Channel Estimation ◽

Relay Node ◽

Spatial Diversity ◽

Relay Network ◽

Destination Node ◽

Training Design ◽

Amplify And Forward ◽

Relay Nodes ◽

Training Scheme ◽

Data Signal

We consider the training design and channel estimation in the amplify-and-forward (AF) diamond relay network. Our strategy is to transmit the source training in time-multiplexing (TM) mode while each relay node superimposes its own relay training over the amplified received data signal without bandwidth expansion. The principal challenge is to obtain accurate channel state information (CSI) of second-hop link due to the multiaccess interference (MAI) and cooperative data interference (CDI). To maintain the orthogonality between data and training, a modified relay-assisted training scheme is proposed to migrate the CDI, where some of the cooperative data at the relay are discarded to accommodate relay training. Meanwhile, a couple of optimal zero-correlation zone (ZCZ) relay-assisted sequences are designed to avoid MAI. At the destination node, the received signals from the two relay nodes are combined to achieve spatial diversity and enhanced data reliability. The simulation results are presented to validate the performance of the proposed schemes.

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