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In this paper, we propose and analyze an turbo coding scheme for optical CDMA systems. It is assumed that optical channel is an intensity modulated (IM) channel and direct-detection scheme is employed to detect the received optical signal. From simulation results, it is demonstrated that bit error probability (BEP) and throughput performance is substantially improved with the number of iterations...
In this paper, we propose a efficient primary user detection method in cognitive radio (CR). We adopt a delay diversity receiver for solving problems of the conventional spectrum detector utilizing multiple antennas, which are the increase in hardware complexity and cost. From simulation results, it is demonstrated that the primary user detector with delay diversity receiver has almost half complexity...
In this paper, we propose co-channel interference (CCI) cancellation strategy for cooperative communication systems in wireless communication network. In the proposed strategy, CCI is mitigated by zero forcing (ZF) or minimum mean square error (MMSE) receivers. Moreover, successive interference cancellation (SIC) efficiently. And we analyzed and simulated the proposed system performance in Rayleigh...
According to dramatic increase of wireless communication demand, more spectrum resources are needed to support considerable and various wireless services. However, limited spectrum resources are regulatory assigned to licensed user and no interference needs to occur from unlicensed user to licensed user. In this paper, we propose efficient decision rule in order to get better chance to detect the...
We propose a Z-HBT line coding for a visible light communication (VLC) system. Z-HBT line coding is defined as follows. First, we apply half bit transition to one bit. Second, we decode encoded bits using difference of bit transition level in one bit duration. As a result, we obtain advantages about synchronization problem and noise effect mitigation at the receiver. We set up outdoor the VLC simulation...
In this paper, the performance of a double binary turbo coded space time block code-ultra wide band (STBC-UWB) system is analyzed and simulated in multi-user environments. From the simulation results, it is demonstrated that the double binary turbo coding technique offers considerable coding gain with reasonable encoding and decoding complexity. It is confirmed that the double binary turbo coding...
Cognitive radio (CR), which is proposed as a technology that utilizes the frequency resources effectively, has studied to relive scarcity of the frequency resources. CR provides opportunistically under-utilize licensed frequency to the secondary user. Spectrum sensing is the most important technology to detect primary user. However, in the wireless channels, according to the effect of fading and shadowing...
In this paper, we analyze and simulate the iterative decoding performance of space time block coded (STBC) pulse position modulation-time hopping (PPM-TH) ultra-wideband (UWB) systems in indoor environments. The indoor wireless channel is modeled as a modified Saleh and Valenzuela (SV) channel, which is proposed as a UWB indoor channel model by IEEE 802.15.SG3a. In order to reduce the iterative decoding...
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...
We propose a modified high density bipolar 3-zeros (HDB3) line coding for a visible light communication (VLC) system. Modified HDB3 line coding is defined as follows. First, we apply half bit transition to HDB3. Second, we decode encoded bits using difference of bit transition level in one bit duration. As a result, we obtain advantages about synchronization problem and noise effect mitigation at...
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...
In this paper, the performance of a non-binary turbo coded ultra wide band (UWB) system is analyzed and simulated in multi-user environments. A binary pulse position modulation-time hopping (BPPM-TH) UWB system is considered. The performance is evaluated in terms of bit error probability. Simulation results demonstrate that the performance of such a UWB system can be substantially improved by increasing...
In this paper we present a new approach for the detection of lip centers based on eye localization that is adopted into a lip reading system in mobile environments. First, the centers of left eyes and right eyes are localized directly. Then we use the geometry characteristics of faces to extract rough lip regions. Next, we use 2 steps of threshold adaptation to binarize lip images. The first threshold...
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