scholarly journals Multi-Media and Multi-Band Based Adaptation Layer Techniques for Underwater Sensor Networks

2019 ◽  
Vol 9 (15) ◽  
pp. 3187 ◽  
Author(s):  
Delphin Raj K M ◽  
Sun-Ho Yum ◽  
Eunbi Ko ◽  
Soo-Young Shin ◽  
Jung-Il Namgung ◽  
...  
Keyword(s):  
Communication Systems ◽  
Multiple Access ◽  
Sensor Nodes ◽  
Underwater Communication ◽  
Frequency Division ◽  
Selection Mechanism ◽  
Multi Media ◽  
Medium Selection ◽  
Adaptation Layer ◽  
Multi Band

In the last few decades, underwater communication systems have been widely used for the development of navy, military, business, and safety applications, etc. However, in underwater communication systems, there are several challenging issues, such as limitations in bandwidth, propagation delay, 3D topology, media access control, routing, resource utilization, and power constraints. Underwater communication systems work under severe channel conditions such as ambient noise, frequency selectivity, multi-path and Doppler shifts. In order to collect and transmit the data in effective ways, multi-media/multi-band-based adaptation layer technology is proposed in this paper. The underwater communication scenario comprises of Unmanned Underwater Vehicles (UUVs), Surface gateways, sensor nodes, etc. The transmission of data starts from sensor nodes to surface gateway in a hierarchical manner through multiple channels. In order to provide strong and reliable communication underwater, the adaptation layer uses a multi-band/multi-media approach for transferring data. Hence, in this paper, existing techniques for splitting the band such as Orthogonal Frequency-Division Multiple Access (OFDMA), Frequency-Division Multiple Access (FDMA), or Orthogonal Frequency-Division Multiplexing (OFDM) are used for splitting the frequency band, and the medium selection mechanism is proposed to carry the signal through different media such as Acoustic, Visible Light Communication (VLC), and Infrared (IR) signals in underwater. For the channel selection mechanism, two phases are involved: 1. Finding the distance of near and far nodes using Manhattan method, and 2. Medium selection and data transferring algorithm for choosing different media.

Resource Allocation in Orthogonal Frequency Division Multiple Access-Long Term Evaluation: Neural Network

2019 ◽  
Vol 16 (12) ◽  
pp. 5026-5031
Author(s):  
Kethavath Narender ◽  
C. Puttamadappa
Keyword(s):  
Neural Network ◽  
Resource Allocation ◽  
Communication Systems ◽  
Multiple Access ◽  
Large Scale ◽  
Cuckoo Search ◽  
Base Station ◽  
Frequency Division ◽  
Term Evaluation

Symmetrical Frequency Division Multiple Access (OFDMA) is utilized in the higher rate Wireless Communication Systems (WCSs). In the correspondence framework, a fem to cell is a little cell in building Base Station (BS), which devours less power, short range, and works in a minimal effort. The fem to cell has little separation among sender and recipient that give higher flag quality. In spite of the favorable position in fem to cell systems, there win critical difficulties in Interference Management. Specifically, impedance between the macro cell and fem to cell turns into the fundamental issue in OFDMA-Long Term Evaluation (OFDMA-LTE) framework. In this paper, the Neural Network and Hybrid Bee Colony and Cuckoo Search based Resource Allocation (NN-HBCCS-RA) in OFDMA-LTE framework is presented. The ideal power esteems are refreshed to dispense every one of the clients in the fem to cell and large scale cell. The NN-HBCCS strategy accomplished low Signal to Interference Noise Ratio (SINR), otherworldly proficiency and high throughput contrasted with customary techniques.

PAPR REDUCTION IN MIMO SC-FDMA- A SURVEY

2015 ◽  
Vol 2 (2) ◽  
Author(s):  
HARSHA PRAKASH ◽  
C.D. SURIYAKALA
Keyword(s):  
Power Amplifier ◽  
Communication Systems ◽  
Multiple Access ◽  
Average Power ◽  
Data Rate ◽  
High Data Rate ◽  
Modulation Method ◽  
Frequency Division ◽  
High Data ◽  
Power Amplifier Efficiency

To meet the requirements of high data rate, third generation partnership project (3GPP) has come across the development of long term evolution (LTE). High data rate can be achieved with the help of an advanced modulation method. Orthogonal Frequency Division Multiple Access (OFDMA) was considered as a modulation method especially in the downlink of the communication systems. It gives many advantages like frequency diversity, increased capacity and robustness against impulse noise. Besides these advantages, a major drawback of OFDMA is its high peak-to-average power ratio (PAPR). High PAPR affects the system by lowering the power amplifier efficiency, increased complexity as well as shorter battery life. In case of uplink communication, where better peak power characteristics benefit the mobile terminals with respect to power efficiency, OFDMA is not a possible solution. To handle such situations, 3GPP has introduced a modified form of OFDMA which is known as Single-Carrier Frequency Division Multiple Access (SC-FDMA). It provides same advantages as OFDMA along with low PAPR. To further improve the bit error rate (BER) performance of the system and power amplifier efficiency Multiple-Input Multiple-Output (MIMO) can be extended to SC-FDMA system. This paper surveys causes, effects and possible solutions of high PAPR in a communication system.

scholarly journals Sparse code multiple access on the generalized frequency division multiplexing

2020 ◽  
Vol 2020 (1) ◽  
Author(s):  
Guilherme P. Aquino ◽  
Luciano L. Mendes
Keyword(s):  
Communication Systems ◽  
Orthogonal Frequency Division Multiplexing ◽  
Multiple Access ◽  
Physical Layer ◽  
Spectrum Efficiency ◽  
Sparse Code ◽  
Frequency Division Multiplexing ◽  
Frequency Division ◽  
Time Frequency ◽  
Performance Loss

Abstract Recent advances in the communication systems culminated in a new class of multiple access schemes, named non-orthogonal multiple access (NOMA), where the main goal is to increase the spectrum efficiency by overlapping data from different users in a single time-frequency resource used by the physical layer. NOMA receivers can resolve the interference among data symbols from different users, increasing the overall system spectrum efficiency without introducing symbol error rate (SER) performance loss, which makes this class of multiple access techniques interesting for future mobile communication systems. This paper analyzes one promising NOMA technique, called sparse code multiple access (SCMA), where C users can share U<C time-frequency resources from the physical layer. Initially, the SCMA and orthogonal frequency division multiplexing (OFDM) integration is considered, defining a benchmark for the overall SER performance for the multiple access technique. Furthermore, this paper proposes the SCMA and generalized frequency division multiplexing (GFDM) integration. Since GFDM is a highly flexible non-orthogonal waveform that can mimic several other waveforms as corner cases, it is an interesting candidate for future wireless communication systems. This paper proposes two approaches for combining SCMA and GFDM. The first one combines a soft equalizer, called block expectation propagation (BEP), and a multi-user detection (MUD) scheme based on the sum-product algorithm (SPA). This approach achieves the best SER performance, but with the significant increment of the complexity at the receiver. In the second approach, BEP is integrated with a simplified MUD, which is an original contribution of this paper, aiming for reducing the receiver’s complexity at the cost of SER performance loss. The solutions proposed in this paper show that SCMA-GFDM can be an interesting solution for future mobile networks.

scholarly journals Performance Analysis of OFDMA vs. NOMA in Cognitive Radio Network

2021 ◽  
Vol 9 (VI) ◽  
pp. 2483-2488
Author(s):  
E. Alwin Richard
Keyword(s):  
Communication Systems ◽  
Orthogonal Frequency Division Multiplexing ◽  
Multiple Access ◽  
Spectrum Efficiency ◽  
Frequency Division Multiplexing ◽  
Frequency Division ◽  
Time Frequency ◽  
New Class ◽  
Overlapping Data ◽  
Multiple Access Schemes

Recent advancements in communication systems have resulted in a new class of multiple access schemes known as non-orthogonal multiple access (NOMA), the primary goal of which is to increase spectrum efficiency by overlapping data from different users in a single time-frequency resource used by the physical layer. NOMA receivers can resolve interference between data symbols from various users, hence increasing throughput. Initially, the combination of SCMA and orthogonal frequency division multiplexing (OFDM) is addressed, establishing a baseline for the overall SER performance of the multiple access strategy. Furthermore, this work suggests the merging of SCMA with generalised frequency division multiplexing (GFDM).GFDM is an intriguing possibility for future wireless communication systems since it is a very flexible non-orthogonal waveform that can imitate various different waveforms as corner cases. This research suggests two methods for integrating SCMA with GFDM.

scholarly journals Image Transmission in 4G LTE using DWT based SC-FDMA System

2018 ◽  
Vol 11 (3) ◽  
pp. 1633-1642
Author(s):  
Padmapriya V. M.
Keyword(s):  
Wireless Communication ◽  
Communication Systems ◽  
Multiple Access ◽  
Image Transmission ◽  
Performance Measure ◽  
Error Rates ◽  
Superior Performance ◽  
Frequency Division ◽  
Single Carrier ◽  
4G Lte

In recent trends, the image transmission over wireless communication system in 4G LTE (Long Term Evolution) grow into a challenging task. OFDMA (Orthogonal Frequency Division Multiple Access) plays a key role in data transmission (text, image and video) over wireless systems. In OFDMA several transformation techniques have been used for the transmission of images. But they have some drawbacks such as increased number of carriers, increased delay estimation, high ISI and ICI. Hence, to overcome these drawbacks, an image transmission over wireless communication is proposed using DWT technique. OFDMA has several benefits like less complexity, high flexibility and high spectral efficiency. However, still, it lacks in noise reduction and increased error rates. To avoid these issues, SC-FDMA (Single Carrier Frequency Division Multiple Access) techniques is introduced in this work for the image transmission over wireless communication systems. In this proposed work, a DWT based SC-FDMA system is implemented to reduce the noise and interference using wavelet transform analysis. The performance measure of SNR, PSNR, BER and MSE for the proposed DWT based SC-FDMA system is evaluated using MATLAB. The results indicate that the proposed technique affords superior performance with a reduced BER.

scholarly journals Design and Development of Novel Channel estimation method for OFDM based Underwater communication

2021 ◽  
Author(s):  
Asha M ◽  
T P Surekha
Keyword(s):  
Channel Estimation ◽  
Communication Systems ◽  
Orthogonal Frequency Division Multiplexing ◽  
Multipath Propagation ◽  
Research Work ◽  
Estimation Method ◽  
Underwater Communication ◽  
Frequency Division ◽  
Transmission Method ◽  
Shift Keying

Abstract The ocean is a constantly changing environment whose properties are still great Challenges to Developing Effective Underwater Wireless Communication represent. The high absorption of electromagnetic and optical signals in the water limits this Use and development of underwater electromagnetic communication systems. A possible approach to wireless underwater communication over longer distances (> 100m), offers acoustic signal transmission, modulation methods such as frequency shift keying are also used (FSK) and phase-shift keying (PSK) are used. In many areas the orthogonal frequency division multiplex method (Orthogonal Frequency Division Multiplexing, OFDM) is enforced for high data rates. It offers a multi-carrier transmission method Benefits in treating multipath propagation, nevertheless achieves a bandwidth efficiency similar to that of corresponding single-carrier processes. In recent studies, the OFDM methods are adopted for underwater communication. However the real time implementation is becoming a challenging part. The channel estimation plays vital role in underwater communication. In this research work, the novel sparse channel estimation in OFDM based underwater communication is proposed for long distances. The proposed algorithms are developed in fixed point manner which can be implemented in FPGA. The BER values are estimated for proposed algorithm and validated with the conventional algorithms. The proposed algorithms exhibits better results compared with the conventional algorithms.

scholarly journals Narrowband Interference Suppression in Wireless OFDM Systems

2009 ◽  
Vol 5 (1) ◽  
Author(s):  
Zlatka Nikolova ◽  
Georgi Iliev ◽  
Miglen Ovtcharov ◽  
Vladimir Poulkov
Keyword(s):  
Communication Systems ◽  
Multiple Access ◽  
Communication Channel ◽  
Digital Data ◽  
Communication Link ◽  
Narrowband Interference ◽  
Frequency Division ◽  
Ofdm Systems ◽  
Signal Distortions ◽  
Channel Distortion

Signal distortions in communication systems occur between the transmitter and the receiver; these distortions normally cause bit errors at the receiver. In addition interference by other signals may add to the deterioration in performance of the communication link. In order to achieve reliable communication, the effects of the communication channel distortion and interfering signals must be reduced using different techniques. The aim of this paper is to introduce the fundamentals of Orthogonal Frequency Division Multiplexing (OFDM) and Orthogonal Frequency Division Multiple Access (OFDMA), to review and examine the effects of interference in a digital data communication link and to explore methods for mitigating or compensating for these effects.

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