Modelling and Simulation of IDMA-OFDM for Underwater Acoustic Communication

2015 ◽  
Vol 65 (4) ◽  
pp. 307 ◽  
Author(s):  
Sangram More ◽  
K. Krishna Naik
Keyword(s):  
Time Delay ◽  
Acoustic Signal ◽  
Communication Systems ◽  
Orthogonal Frequency Division Multiplexing ◽  
Signal Transmission ◽  
Simulated Data ◽  
Delay Spread ◽  
Underwater Acoustic Communication ◽  
Long Time ◽  
Multi Access

<p>The Ocean exhibits phenomenon of changing acoustic signal transmission due to its non-stationary nature. Water columns in between transmitter and receiver are not fixed at any point of time. Thus, designing of a wireless communication systems for underwater applications becomes significantly challenging. The speed of sound in water is 1500 m/s which introduces large delay spread in acoustic signal due to multipath phenomenon. The large time delay causes Inter-symbol Interference; this ISI degrades the performance of many receivers. However orthogonal frequency division multiplexing is multi-tone modulation reduces long time delay spreads of acoustic channels. The interleave division multiple access distinguishes each user with the unique random interleaver code. The IDMA-OFDM is superior design for reducing error bursts in multi-access underwater applications. A Simulink based simulation modell of IDMA-OFDM system has been discussed in this paper. Satisfactory performance of the implementation was observed through analysis of BER with respect to SNR. The results have been concluded by comparing simulated data in BER tool of Simulink.</p><p><strong>Defence Science Journal, Vol. 65, No. 4, July 2015, pp. 307-311, DOI: http://dx.doi.org/10.14429/dsj.65.8606</strong></p>

scholarly journals Gaussian Pulse-Based Two-Threshold Parallel Scaling Tone Reservation for PAPR Reduction of OFDM Signals

2011 ◽  
Vol 2011 ◽  
pp. 1-9 ◽  
Author(s):  
Lei Guan ◽  
Anding Zhu
Keyword(s):  
Time Delay ◽  
Communication Systems ◽  
Orthogonal Frequency Division Multiplexing ◽  
Hardware Implementation ◽  
Average Power ◽  
Computational Cost ◽  
Gaussian Pulse ◽  
High Signal ◽  
Tone Reservation ◽  
Ofdm Signals

Tone Reservation (TR) is a technique proposed to combat the high Peak-to-Average Power Ratio (PAPR) problem of Orthogonal Frequency Division Multiplexing (OFDM) signals. However conventional TR suffers from high computational cost due to the difficulties in finding an effective cancellation signal in the time domain by using only a few tones in the frequency domain. It also suffers from a high cost of hardware implementation and long handling time delay issues due to the need to conduct multiple iterations to cancel multiple high signal peaks. In this paper, we propose an efficient approach, calledtwo-threshold parallel scaling,for implementing a previously proposed Gaussian pulse-based Tone Reservation algorithm. Compared to conventional approaches, this technique significantly reduces the hardware implementation complexity and cost, while also reducing signal processing time delay by using just two iterations. Experimental results show that the proposed technique can effectively reduce the PAPR of OFDM signals with only a very small number of reserved tones and with limited usage of hardware resources. This technique is suitable for any OFDM-based communication systems, especially for Digital Video Broadcasting (DVB) systems employing large IFFT/FFT transforms.

scholarly journals Interference Cancellation Using Replica Signal for HTRCI-MIMO/OFDM in Time-Variant Large Delay Spread Longer Than Guard Interval

2012 ◽  
Vol 2012 ◽  
pp. 1-10 ◽  
Author(s):  
Yuta Ida ◽  
Chang-Jun Ahn ◽  
Takeshi Kamio ◽  
Hisato Fujisaka ◽  
Kazuhisa Haeiwa
Keyword(s):  
Interference Cancellation ◽  
Communication Systems ◽  
Orthogonal Frequency Division Multiplexing ◽  
Transmission Rate ◽  
Delay Spread ◽  
High Time Resolution ◽  
Large Delay ◽  
Guard Interval ◽  
Maximum Delay ◽  
Mimo Ofdm

Orthogonal frequency division multiplexing (OFDM) and multiple-input multiple-output (MIMO) are generally known as the effective techniques for high data rate services. In MIMO/OFDM systems, the channel estimation (CE) is very important to obtain an accurate channel state information (CSI). However, since the orthogonal pilot-based CE requires the large number of pilot symbols, the total transmission rate is degraded. To mitigate this problem, a high time resolution carrier interferometry (HTRCI) for MIMO/OFDM has been proposed. In wireless communication systems, if the maximum delay spread is longer than the guard interval (GI), the system performance is significantly degraded due to the intersymbol interference (ISI) and intercarrier interference (ICI). However, the conventional HTRCI-MIMO/OFDM does not consider the case with the time-variant large delay spread longer than the GI. In this paper, we propose the ISI and ICI compensation methods for a HTRCI-MIMO/OFDM in the time-variant large delay spread longer than the GI.

RECURSIVE QR DECOMPOSITION ARCHITECTURE FOR MIMO-OFDM DETECTION SYSTEMS

2013 ◽  
Vol 22 (02) ◽  
pp. 1250078 ◽  
Author(s):  
ROBERT CHEN-HAO CHANG ◽  
HUNG-LIEH CHEN ◽  
KUANG-HAO LIN ◽  
MING-FAN WEI
Keyword(s):  
Communication Systems ◽  
Orthogonal Frequency Division Multiplexing ◽  
Mimo Systems ◽  
Signal Transmission ◽  
Estimation Method ◽  
Detection Algorithm ◽  
Qr Decomposition ◽  
Cordic Algorithm ◽  
Data Detection ◽  
Mimo Ofdm

This paper presents a modified implementation of QR decomposition for multiple input multiple output-orthogonal frequency division multiplexing (MIMO-OFDM) detection based on the Givens rotation method. The QR decomposition hardware is constructed using the coordinate rotation digital computer (CORDIC) algorithm operating with fewer gate counts and lower power consumption than do triangular systolic array (TSA) structures. Accurate signal transmission is essential to wireless communication systems. Thus, a more effective data detection algorithm and precise channel estimation method play vital roles in MIMO systems. Implementing data detection with QR decomposition helps reduce the complexity of MIMO-OFDM detection. Implementation results reveal that the proposed recursive QR decomposition (RQRD) architecture has lower clock latency than do TSA structures, and has a smaller hardware area than do Gram–Schmidt structures.

scholarly journals Triangular Slot-Loaded Wideband Planar Rectangular Antenna Array for Millimeter-Wave 5G Applications

Electronics ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 778
Author(s):  
Iftikhar Ahmad ◽  
Houjun Sun ◽  
Umair Rafique ◽  
Zhang Yi
Keyword(s):  
Antenna Array ◽  
Millimeter Wave ◽  
Communication Systems ◽  
Ground Plane ◽  
Simulated Data ◽  
Impedance Bandwidth ◽  
Antenna Element ◽  
Single Antenna ◽  
Rectangular Patch ◽  
Half Power

This paper presents a design of a triangular slot-loaded planar rectangular antenna array for wideband millimeter-wave (mm-wave) 5G communication systems. The proposed array realizes an overall size of 35.5 × 14.85 mm2. To excite the array elements, a four-way broadband corporate feeding network was designed and analyzed. The proposed array offered a measured impedance bandwidth in two different frequency ranges, i.e., from 23 to 24.6 GHz and from 26 to 45 GHz. The single-antenna element of the array consists of a rectangular patch radiator with a triangular slot. The partial ground plane was used at the bottom side of the substrate to obtain a wide impedance bandwidth. The peak gain in the proposed array is ≈12 dBi with a radiation efficiency of >90%. Furthermore, the array gives a half-power beamwidth (HPBW) of as low as 12.5°. The proposed array has been fabricated and measured, and it has been observed that the measured results are in agreement with the simulated data.

Long-time dynamics of a class of nonlocal extensible beams with time delay

2021 ◽  
pp. 108128652110194
Author(s):  
Fengjuan Meng ◽  
Cuncai Liu ◽  
Chang Zhang
Keyword(s):  
Time Delay ◽  
Stability Property ◽  
Beam Equation ◽  
Exponential Attractors ◽  
Time Dynamics ◽  
Bounded Smooth Domain ◽  
Finite Dimensional ◽  
Long Time ◽  
Bounded Smooth ◽  
Long Time Dynamics

This work is devoted to the following nonlocal extensible beam equation with time delay: [Formula: see text] on a bounded smooth domain [Formula: see text]. The main purpose of this paper is to consider the long-time dynamics of the system. Under suitable assumptions, the quasi-stability property of the system is established, based on which the existence and regularity of a finite-dimensional compact global attractor are obtained. Moreover, the existence of exponential attractors is proved.

scholarly journals Measurement-device-independent quantum key distribution with leaky sources

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Weilong Wang ◽  
Kiyoshi Tamaki ◽  
Marcos Curty
Keyword(s):  
Quantum Key Distribution ◽  
Communication Systems ◽  
Signal Transmission ◽  
Information Leakage ◽  
Key Distribution ◽  
Time Frame ◽  
Measurement Device ◽  
Decoy State ◽  
Unrealistic Assumption ◽  
Measurement Device Independent

AbstractMeasurement-device-independent quantum key distribution (MDI-QKD) can remove all detection side-channels from quantum communication systems. The security proofs require, however, that certain assumptions on the sources are satisfied. This includes, for instance, the requirement that there is no information leakage from the transmitters of the senders, which unfortunately is very difficult to guarantee in practice. In this paper we relax this unrealistic assumption by presenting a general formalism to prove the security of MDI-QKD with leaky sources. With this formalism, we analyze the finite-key security of two prominent MDI-QKD schemes—a symmetric three-intensity decoy-state MDI-QKD protocol and a four-intensity decoy-state MDI-QKD protocol—and determine their robustness against information leakage from both the intensity modulator and the phase modulator of the transmitters. Our work shows that MDI-QKD is feasible within a reasonable time frame of signal transmission given that the sources are sufficiently isolated. Thus, it provides an essential reference for experimentalists to ensure the security of implementations of MDI-QKD in the presence of information leakage.

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