Non‐orthogonal frequency division multiplexing based on sparse representation

Fu, Xiaomei; Chen, Li; Yang, Jingyu

doi:10.1049/iet-com.2017.1260

Cited by 8 publications

(3 citation statements)

References 24 publications

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“…The received signal can be re-formulated as: (15) Where fT   ΗI , so ( 15) is regarded as non-orthogonal based received signal. We have applied time-domain equalizer, where equalizer length is chosen to be 3-5 times of channel delay spread, results in symbol estimation of ε: (16) where 𝛔 0 2 is the variance for the noise mentioned in (16). In our proposed non-orthogonal FDM, symbol estimation is done by averaging the signal power when subcarrier spacing is almost half of the traditional spacing of ∆f = 1/T.…”

Section: Time-domain Equalizermentioning

confidence: 99%

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A Novel Receiver Design of Nonorthogonal FDM Systems in Underwater Acoustics Communication

Anwar

Yuen

Sun

et al. 2020

IEEE Systems Journal

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While Orthogonal Frequency Division Multiplexing (OFDM) has been studied for a decade, the study of Non-Orthogonal Frequency Division Multiplexing (NOFDM) in underwater acoustics (UWA) communication has never been reported, to the best of our knowledge. Therefore, we investigate NOFDM technique for UWA communication considering the doubly-dispersive channel. The main feature of NOFDM is that it involves more closely packed subcarriers compared to OFDM, which results in higher spectral efficiency. However, this transmission suffers from severe Inter-Carrier-Interference (ICI). Since, we are considering doubly-dispersive channel, Inter-Symbol-Interference (ISI) is also encountered due to multipath propagation. Therefore, traditional receiver of NOFDM system in UWA channel, tends to have high computational complexity. Considering this problem, we design a receiver for NOFDM system, where Basis Expansion Model (BEM) is used along with Compressed Sensing (CS) channel estimation technique i.e., Orthogonal Matching Pursuit (OMP), which can effectively reduce the computational complexity. However, while implementing this technique in the real sea environment, the problem of long delay / Doppler spread is encountered due to guard intervals. Therefore, we propose the use of time domain equalizer, to mitigate the effect of long delay / Doppler spread. Simulation and experimental results based on Bit Error Rate (BER) demonstrate performance degradation due to severe interference in our proposed receiver. On the contrary, Mean Square Error (MSE) performance shows that our proposed receiver with OMP channel estimation outperforms OFDM receiver. Similarly, higher spectral efficiency gain is attained due to closely packed subcarriers.

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Section: Time-domain Equalizermentioning

confidence: 99%

“…Similarly, in [12], [4], [13], [14], the technique of NOFDM system is proposed for wireless communication. This interesting technique features non-orthogonality/overlapping of symbols/subcarriers, as can be seen in [15], [16], [17]. This overlapping results in ISI / ICI.…”

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confidence: 99%

A Novel Receiver Design of Nonorthogonal FDM Systems in Underwater Acoustics Communication

Anwar

Yuen

Sun

et al. 2020

IEEE Systems Journal

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“…Where [ ] is the carrier in the OFDM modulator, k and n represent the frequency index and time index of subcarriers, respectively and N is the sampling time and the total number of orthogonal subcarriers in OFDM [9]. To generate subcarriers of the proposed channel matched OFDM, we select a subset of K (K < N) OFDM subcarriers, and rows which represents non-selected subcarriers, in G matrix will be set to zero to obtain a new matrix defined by,…”

Section: System Modelmentioning

confidence: 99%

Channel-Matched OFDM (CM-OFDM) for Enhanced Performance of Multiuser Systems Operating in Underwater Acoustic Channels

El‐Khamy

Ibrahim²

EPiC Series in Computing

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The design of multiuser OFDM underwater acoustic (UWA) communication systems is very challenging due to the time-varying and frequency selective fading of UWA channels. The key for ensuring a reliable optimum transmission for every user is the suitable resource assignment for each. This paper proposes a new adaptive channel- matched OFDM scheme (CM-OFDM) to overcome the performance degradation caused by the frequency selective fading across the OFDM subcarriers. In the proposed scheme, the OFDM subcarriers are sorted depending on their corresponding channel gains. Then the resource assignment to the different users is accomplished according to their required quality of service (QOS). The user with the highest QOS is assigned the best subcarriers and the other users are similarly assigned the remaining subcarriers. This optimized resource assignment technique guarantees enhanced performance with no need of increasing the transmitted power or changing the modulation schemes. The performance of the proposed technique is investigated and is compared with uniform and random subcarriers’ assignment methods used for multiuser OFDM systems. The simulations are performed for a multipath frequency selective UWA channel model. The simulation results clearly show the advantages of CM-OFDM scheme for the users with high QOS on the expense of a slight degradation in the performance for the other user with lower QOS.

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Sparse Non-Orthogonal Frequency Division Multiplexing for Secure Transmission Over Broadcast Channels

El‐Khamy

Ibrahim²,

Banawan

2021

IEEE Access

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Non‐orthogonal frequency division multiplexing based on sparse representation

Cited by 8 publications

References 24 publications

A Novel Receiver Design of Nonorthogonal FDM Systems in Underwater Acoustics Communication

A Novel Receiver Design of Nonorthogonal FDM Systems in Underwater Acoustics Communication

Channel-Matched OFDM (CM-OFDM) for Enhanced Performance of Multiuser Systems Operating in Underwater Acoustic Channels

Sparse Non-Orthogonal Frequency Division Multiplexing for Secure Transmission Over Broadcast Channels

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