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Device-to-device (D2D) communication is a salient function of public safety networks for enabling communications, even in a disaster environment where the communication infrastructures are fully or partially destroyed. In order that devices directly communicate, they must first find and identify each other. Especially, in a disaster environment where wireless channel conditions may be very poor, discovery...
In this paper, characteristics of transmission and receive of RGB (Red/Green/Blue) light emitting diodes (LEDs) are analyzed for LED identification (LED-ID) systems. LED is considered as a future light technology because of advantages of LED such as the long life time, low power consumption and high power efficiency. Moreover, LED is used to lighting device also, it can be used a communication device,...
In this paper, we propose clipping scheme and equalizer as methods to reduce the effects of impulsive noise and channel attenuation in power line communication (PLC) system. Clipping is cutting off amplitude of the received signal over threshold level without its phase change and the equalizer compensates effects of PLC channel. The performance is evaluated in terms of bit error rate (BER). From simulation...
In this paper, we propose and simulate double binary turbo code for high speed power line communication (PLC) system. In order to make power line channel environments, Bernoulli-Gaussian noise is considered. The performance is evaluated in terms of bit error probability. From the simulation results, it is demonstrated that the double binary turbo coding scheme offers considerable coding gain with...
In indoor visible light communication channels and LED road illumination communications for the Intelligent Transport Systems (ITS), inter symbol interference (ISI) due to multipath propagation prevents high data rate transmission. Indoor wireless optical communication systems utilizing white LED lights and on the road illumination have been studying about it. Generally, plural lights are installed...
As the demand of high quality service in next generation wireless communication systems, a high performance of data transmission requires an increase of spectrum efficiency and an improvement of error performance in wireless communication systems. In this paper, we propose a multi-user multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) system with cyclic delay...
High transmission data rate, spectral efficiency, and reliability are necessary for future wireless communications systems. In this paper, we study the performance of multi-user multiple-input multiple-output channel estimation methods using training sequences. We consider the popular linear least square (LS) and minimum mean-square-error (MMSE) approaches. The results of computer simulation show...
As the demand of high quality service in next generation wireless communication systems, a high performance of data transmission requires an increase of spectrum efficiency and an improvement of error performance in wireless communication systems. In this paper, we propose a multi-user multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) system with cyclic delay...
There are a few core technologies to enable high-performance 4th generation (4G) broadband wireless communication system. A multiple input multiple output (MIMO) provides high-rate transmission through expended channels by multiple array antennas in both sender and receiver side. Also orthogonal frequency division multiplexing (OFDM) is well-known as the most appropriate technique for high data rate...
In this paper, performance of double binary turbo coded orthogonal frequency division multiplexing (OFDM) system is analyzed and simulated in power line communications (PLC) channel. In order to make power line channel environments, Bernoulli-Gaussian noise is considered. The performance is evaluated in terms of bit error probability. From the simulation results, it is demonstrated that the double...
In this paper, we present and analyze efficient frame synchronization and frequency offset compensation scheme with ternary sequences for an orthogonal frequency division multiplexing (OFDM) system in Rayleigh fading channels. Frame synchronization is an essential procedure for normal operation of the OFDM system because of sensitivity to synchronization errors. And when there are frequency offsets...
In this paper, performance of double binary turbo coded orthogonal frequency division multiplexing (OFDM) system is analyzed and simulated in power line communications (PLC) channel. In order to make power line channel environments, Bernoulli-Gaussian noise is considered. The performance is evaluated in terms of bit error probability. From the simulation results, it is demonstrated that the double...
Orthogonal frequency division multiplexing (OFDM) modulation using orthogonal subcarriers reduces the delay spread by increasing robustness to multipath fading and can use overlapped bandwidth due to orthogonality on frequency domain. Thus, OFDM has been adopted for high speed data transmission of multimedia traffic such as HomePlug A/V and Mobile WiMax. However, OFDM also has a drawback of a high...
Today, the improved wireless communication technique for increasing demand for the next generation communication system is developed variously to transmit a long distance and high data. Visible light communication (VLC) system uses radiated light of LEDs. However, VLC have weak points which deteriorate performance of communication. Because there is multi-path fading that occurs propagation delay by...
Orthogonal frequency division multiplexing (OFDM) modulation using orthogonal subcarriers reduces the delay spread by increasing robustness to multipath fading and can use overlapped bandwidth due to orthogonality on frequency domain. Thus, OFDM has been adopted for high speed data transmission of multimedia traffic. However, OFDM also has a drawback of a high peak-to-average-power-ratio (PAPR). This...
As the demand of high quality service in next generation wireless communication systems, a high performance of data transmission requires an increase of spectrum efficiency and an improvement of error performance in wireless communication systems. In this paper, we propose a multi-user multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) system with adaptive modulation...
Cognitive radio technology is proposed for using the unused spectrum band efficiently because of the spectrum scarcity problem. Among the cognitive radio technologies, a key technology is signal detection through spectrum sensing that detects reliably primary user signal. Then, cooperative spectrum sensing has been proposed to enhance the signal detection performance. In this paper, we focus on the...
Frame synchronization is an critical factor for an effective operation of OFDM(orthogonal frequency division multiplexing) schemes. In this paper, we propose and analyze an efficient frame synchronization method based on m-sequence of OFDM format for high-speed power line communication systems. Repeated m-sequence is superimposed directly to OFDM frames in the time domain. By utilizing the autocorrelation...
This paper presents a solution for the frame boundary detection to support all band groups at the overall bandwidth of 3.1-10.6 GHz in the multiband-OFDM system. This solution is based on the sign variations of the autocorrelation outputs of the received signals according to the carrier frequency offset and covers the full-range frequency tolerance for all band groups.
Frame synchronization is an critical factor for an effective operation of OFDM (orthogonal frequency division multiplexing) based communication systems. In this paper, we present and analyze an efficient frame synchronization method based on m-sequence for OFDM-based mobile multimedia communication systems. Repeated m-sequence is superimposed directly to OFDM frames in the time domain. By utilizing...
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