Overcoming the SNR-wall for energy detection using the autocorrelation of cyclic prefix based OFDM signal

2013 ◽  
Author(s):  
Sandip Karar ◽  
Abhirup Das Barman
Keyword(s):  
Energy Detection ◽  
Cyclic Prefix ◽  
Ofdm Signal ◽  
Snr Wall

scholarly journals SPECTRUM SENSING USING CYCLIC PREFIX IN COGNITIVE RADIO WIRELESS SYSTEM

2013 ◽  
pp. 123-127
Author(s):  
T. NAGAMANI ◽  
M.V. SUDHAKAR ◽  
E. ADINARAYANA
Keyword(s):  
Cognitive Radio ◽  
User Satisfaction ◽  
Wireless Systems ◽  
Energy Detection ◽  
Substantial Improvement ◽  
Cyclic Prefix ◽  
Short Message ◽  
Spectrum Utilization ◽  
Primary Signal

The rapid growth of wireless communications has made the problem of spectrum utilization ever more critical. The increasing diversity (voice, short message, Web & multimedia) and demand of high quality-of-service (QoS) applications have resulted in overcrowding of the allocated (officially sanctioned) spectrum bands, leading to significantly reduced levels of user satisfaction. The concepts of GLRT algorithm and substantial improvement over the U-GLRT algorithm are explained. This paper presents a model which uses efficient CP method for CR in Wireless Systems. Primary signal has been detected in the OFDM transmission with both the CPCC and MP–based C-GLRT algorithms greatly outperform energy detection in multi path environment has been implemented using software design. The signal model in our analysis is to efficiently exploit the correlation among the transmitted signals due to the presence of CP. Proposed method of cognitive radio takes two steps of implementation .first named as MP based is to detect the noise and de-noise the signal and the second is cp based in which the signals are identified based on the cyclic prefix.

Effect of Raman Amplifier and Cyclic Prefix on O-OFDM System Using Phase Modulation

2015 ◽  
Vol 36 (3) ◽  
Author(s):  
Harmandeep Kaur ◽  
Kamajit Singh Bhatia
Keyword(s):  
Pump Power ◽  
System Performance ◽  
Phase Modulation ◽  
Single Channel ◽  
Electrical Power ◽  
Cyclic Prefix ◽  
Raman Amplifier ◽  
Transmission Distance ◽  
Gain Variation ◽  
Ofdm Signal

AbstractThe system performance of single channel OFDM at 10-Gbps data rate using phase modulation under the effect of Raman amplifier and varying cyclic prefix of OFDM signal is evaluated. Pump power of single pumping type co-propagating Raman amplifier is varied and the results are analyzed for different fiber length through simulation. Raman gain variation is observed with increasing Raman pump power and it shows that increasing the pump power will improve the system performance. Also it reveals the fact that with an application of Raman amplifier the transmission distance will increase. Further received electrical power is observed with variation in cyclic prefix. Electrical output power is detected in each case. Moreover optical spectrums are examined with and without amplifier.

Lowering the SNR Wall for Energy Detection Using Cross-Correlation

2011 ◽  
Vol 60 (8) ◽  
pp. 3748-3757 ◽  
Author(s):  
Mark S. Oude Alink ◽  
Andre B. J. Kokkeler ◽  
Eric A. M. Klumperink ◽  
Gerard J. M. Smit ◽  
Bram Nauta
Keyword(s):  
Cross Correlation ◽  
Energy Detection ◽  
Snr Wall

scholarly journals Optimal Selection of Cyclic-Prefix and Sub-Carrier for OFDM Signal in Mobile Satellite Communications Channel

2013 ◽  
Vol 756-759 ◽  
pp. 1194-1198
Author(s):  
Bin Li ◽  
Wei Zheng ◽  
Shu Bo Ren ◽  
Jian Jun Wu
Keyword(s):  
Performance Improvement ◽  
Satellite Communications ◽  
Cyclic Prefix ◽  
System Capacity ◽  
Delay Spread ◽  
Optimal Parameters ◽  
Ofdm Signal ◽  
Mobile Satellite ◽  
Ofdm Signals ◽  
Selection Of

Adapted parameters of OFDM signals can bring performance improvement in mobile satellite communications. This paper firstly analyzes the effect of cyclic-prefix (CP) length and sub-carrier bandwidth on system interference and capacity. This effect can be described by a formula which consists of system capacity, CP length and sub-carrier bandwidth. Then using this formula, a method to select the optimal parameters is given. In the end, a numerical calculation is performed to figure out the optimal parameters, considering the multipath delay spread and Doppler spread in satellite channel. It comes up that in satellite channel the CP is not very effective to improve the system performance and a wider sub-carrier bandwidth is desired.

scholarly journals Performance of Hybrid Sensing Method in Environment with Noise Uncertainty

2018 ◽  
Vol 1 ◽  
pp. 51-57 ◽  
Author(s):  
Mateusz Kustra ◽  
Krzysztof Kosmowski ◽  
Marek Suchański
Keyword(s):  
Spectral Density ◽  
Power Estimation ◽  
Energy Detection ◽  
System Model ◽  
Noise Power ◽  
Absolute Value ◽  
Ofdm Signal ◽  
Simulation Results ◽  
Hybrid Detector ◽  
Communications System

The paper presents a novel hybrid spectrum sensing method used in cognitive radio and presents a hybrid detector (HD) which improves the sensing performance. The proposed HD takes advantage of the energy detection (ED) principle and a method based on Covariance Absolute Value (CAV), as well as on Cyclic Autocorrelation Function (CAF). The paper shows the limitations of using ED, resulting from the uncertainty of spectral density of noise power estimation, known as the SNR wall. The paper describes a system model and presents simulation results for the OFDM signal of a WiMAX-based communications system. The simulation results refer to an ideal environment with well-known parameters, and to an environment with uncertain spectral density of noise power estimation.

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
Keyword(s):  
Impulse Response ◽  
Channel Capacity ◽  
Cyclic Prefix ◽  
Monotonic Function ◽  
Channel Impulse Response ◽  
Ofdm System ◽  
Ofdm Signal

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.

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