Analysis of the Channel Capacity under OFDM System with Insufficient CP

2014 ◽  
Vol 986-987 ◽  
pp. 2052-2055
Author(s):  
Xin Ya Liu ◽  
Hong Wen Yang

The standard OFDM signal requires a cyclic prefix (CP) of length larger than the channel impulse response. This paper investigates the effect of CP length to the capacity of OFDM system. We have found that full CP or none CP may not be optimal in the sense of capacity. Specifically, the capacity is a monotonic function of CP length in the low and high SNR regime and is approximately concave down when SNR is about 3dB.

2012 ◽  
Vol 11 (1) ◽  
pp. 1-8 ◽  
Author(s):  
Dustin Maas ◽  
Mohammad H. Firooz ◽  
Junxing Zhang ◽  
Neal Patwari ◽  
Sneha K. Kasera

2018 ◽  
Vol 189 ◽  
pp. 04016
Author(s):  
Viet-Hung Nguyen ◽  
Minh-Tuan Nguyen ◽  
Yong-Hwa Kim

Orthogonal frequency division multiplexing (OFDM) is widely used in wired or wireless transmission systems. In the structure of OFDM, a cycle prefix (CP) has been exploited to avoid the effects of inter-symbol interference (ISI) and inter-carrier interference (ICI). This paper proposes a new approach to transmit the signals without CP transmission. Using the deep neural network, the proposed OFDM system transmits data without the CP. Simulation results show that the proposed scheme can estimate the CP at the receiver and overcome the effect of ISI.


Author(s):  
Sarah Zanafi ◽  
Noura Aknin

<span>In this work, the influence of the cyclic prefix on the performance of the OFDM system is studied. We worked out an OFDM transceiver using a 16 QAM modulation scheme, a comparison of the BER for various lengths of the cyclic prefix has been achieved, and the influence of the noise introduced in the channel has been highlighted, for both a Gaussian and Rayleigh noise. The simulation was carried out on MATLAB where the curves of the BER for various lengths of the cyclic prefix are given and compared. We also adopted as a metric the QAM constellation to show the dispersion of the carriers as a consequence of the transmission channel, the mitigation of this effect by the CP is noticeable.</span>


Author(s):  
Hussein A. Leftah ◽  
Huda N. Alminshid

<p>Multiple input-multiple output (MIMO) is a multipath diversity exploring approach which is emerged with orthogonal frequency division multiplexing (OFDM) to produce MIMO-OFDM that is widely used in wireless communications. This paper presents a discrete Hart-ley transform (DHT) precoded MIMO-OFDM system over multipath frequency-selective fading channel with large-size quadrature amplitude modulation (16-QAM, 64-QAM and 256-QAM). A mathematical models for the BER and channel capacity over mutlipath fading channels are also derived in this paper. Average Bit-error-rate (BER) and channel capacity of the presented system is considered and compared with that of the traditional MIMO-OFDM. Simulation results shows that the transmission performance and channel capacity of the proposed schemes is better than that of the traditional MIMO-OFDM without a pre-coder.</p>


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