On channel estimation and detection for amplify-and-forward orthogonal frequency division multiplexing-based two-way relay systems under unknown non-reciprocal doubly selective fading channels

2014 ◽  
Vol 8 (3) ◽  
pp. 378-389 ◽  
Author(s):  
Ke Zhong ◽  
Xia Lei ◽  
Su Hu ◽  
Shaoqian Li
Keyword(s):  
Channel Estimation ◽  
Fading Channels ◽  
Orthogonal Frequency Division Multiplexing ◽  
Frequency Division Multiplexing ◽  
Frequency Division ◽  
Selective Fading ◽  
Amplify And Forward ◽  
Relay Systems

The Diversity Gains of Amplify-and-Forward Relay System with Frequency Selective Channels

2014 ◽  
Vol 644-650 ◽  
pp. 4297-4302
Author(s):  
Y.H. Ding ◽  
R.J. Tian ◽  
K. Xue ◽  
Y. Tian ◽  
X.C. Wang ◽  
...  
Keyword(s):  
Orthogonal Frequency Division Multiplexing ◽  
Frequency Division Multiplexing ◽  
Frequency Division ◽  
Amplify And Forward ◽  
Relay System ◽  
Relay Systems ◽  
Frequency Selective ◽  
Multiple Relay ◽  
Frequency Selective Channels ◽  
Diversity Gains

The diversity gains of amplify-and-forward (AF) relay system with frequency selective channels are discussed. The orthogonal frequency division multiplexing (OFDM) is applied to overcome the inter-symbol interference. The diversity gains are presented for single and multiple relay systems with detailed derivations.

Channel Estimation for OFDM System with Regularized Total Least-Squares Solution

2011 ◽  
Vol 467-469 ◽  
pp. 1621-1626
Author(s):  
Tong Liang Fan ◽  
Lian Qing Fu
Keyword(s):  
Channel Estimation ◽  
Least Squares ◽  
Fading Channels ◽  
Orthogonal Frequency Division Multiplexing ◽  
Total Least Squares ◽  
Coherent Detection ◽  
Frequency Division Multiplexing ◽  
Frequency Division ◽  
Ofdm Systems ◽  
Regularized Total Least Squares

Orthogonal frequency-division multiplexing (OFDM) combines the advantages of high performance and relatively low implementation complexity. However, for reliable coherent detection of the input signal, the OFDM receiver needs accurate channel information. The Doppler shift of fast-fading channels will generate inter-carrier interference (ICI) and, hence, degrade the performance of orthogonal frequency-division multiplexing (OFDM) systems. In this paper, we present regularized total least-squares (RTLS) scheme to eliminate the ICI and noise. A closed-form mathematical expression has been derived to express the channel estimation. It has been shown that the proposed channel estimation and data detect can effectively eliminate the ICI effect.

Proof of Optimality of Ordered Subcarrier Pairing in Amplify-and-Forward OFDM Relay Systems without Diversity

2013 ◽  
Vol 427-429 ◽  
pp. 1064-1067
Author(s):  
Qing Yi Quan
Keyword(s):  
Orthogonal Frequency Division Multiplexing ◽  
Relay Node ◽  
System Capacity ◽  
Frequency Division Multiplexing ◽  
Noise Power ◽  
Frequency Division ◽  
Amplify And Forward ◽  
Signal To Noise ◽  
Relay Systems ◽  
Subcarrier Pairing

Amplify-and-forward (AF) orthogonal frequency division multiplexing (OFDM) relay systems without diversity are studied, with emphasizing on the subcarrier pairing at the relay node. Using the subcarrier pairing based on the signal-to-noise power ratios (SNRs) of subcarriers, it is proven that the ordered subcarrier pairing (OSP), according to normalized channel gains of the subcarriers of OFDM at two hops, is optimal in terms of system capacity, without any assumption for SNRs of subcarriers and types of power constraints. The proof about the optimality of OSP shows that in this kind of relay systems, the subcarrier pairing and power allocation are completely decoupled.

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