• Journal of information and communication convergence engineering
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• v.8 no.5
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• pp.498-501
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• 2010

In this paper, we extend ultra-wideband (UWB) single input single output (SISO) systems with a hybrid pulse amplitude and position modulation (PAPM) to single input multiple output (SIMO) systems using receive antenna diversity. The performance of a rake receive diversity combining scheme for UWB SIMO systems with a PAPM is examined in a log-normal multipath fading channel and also compared with that of a time-switched transmit diversity (TSTD) multiple input single output (MISO) system. It is seen that as the number of receive antennas increases, the receive diversity combining system improves the error performance. It is shown that the TSTD UWB MISO systems offer the performance equivalent to the receive diversity combining scheme for SIMO systems.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.4A
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• pp.307-314
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• 2010

In this paper, a receive diversity combining technique is proposed for single-carrier frequency division multiple access (SC-FDMA)-based cooperative relay systems when discrete Fourier transform (DFT) spreading sizes for mobile station (MS) and relay station (RS) are different. The proposed technique is composed of a DFT spreading size adjustment block, a phase rotation compensation block, a channel phase compensation block, and a receive diversity combining block. The proposed technique is robust to multipath channels and can be operated with a relatively small computational complexity because receive diversity combining is performed with scalar operations in the frequency-domain. It is shown by computer simulation that the proposed receive diversity combining techniques achieve a performance gain over the conventional maximal ratio combining (MRC) techniques for SC-FDMA-based cooperative relay systems.

• Journal of Industrial Technology
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• v.24 no.B
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• pp.187-192
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• 2004

In this paper, we introduce a packet diversity scheme to increase uplink channel utilization in a wireless network where forward error correction is used. The packet diversity allows neighbor base stations to receive uplink packets from a mobile terminal in order to increase the utilization of the uplink channel. By allowing multiple base stations to receive the same packets, we can improve the error correction capability in an uplink channel. By incorporating the packet diversity we can reduce the parity overhead of each packet for a given tolerable loss probability, which improves the link efficiency.

• Journal of Broadcast Engineering
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• v.11 no.2 s.31
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• pp.222-228
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• 2006

In this paper, we propose a receive diversity method for orthogonal frequency division multiplexing (OFDM) systems with cochannel interference. In the method, combining is done in the frequency domain by using the subcarrier based maximum ratio combining (MRC) method. For MRC, we exploit the power of cochannel interference as well as the power of channel noise. The accuracy of the power estimate of interference plus noise is enhanced by averaging the initial estimates over the correlated subchannels where the coherency between the subchannel gains comes from the limited delay spread of the channel. Simulation results show that the proposed method yields 2-3.5dB gain of signal to noise ratio compared to the conventional MRC method and less than 1 dB difference to the ideal case.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.6 no.11
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• pp.3026-3045
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• 2012

In this paper, diversity-multiplexing tradeoff (DMT) of three-user wireless multiple-antenna cooperative systems is investigated in general fading channels when half-duplex and decode-and-forward relay is employed. Three protocols, i.e., adaptive protocol, receive diversity protocol, and dual-hop relaying protocol, are considered. The general fading channels may include transmit and/or receive correlation and nonzero channel means, and are extensions of independent and identically distributed Rayleigh or Rician fading channels. Firstly, simple DMT expressions are derived for general fading channels with zero channel means and no correlation when users employ arbitrary number of antennas. Explicit DMT expressions are also obtained when all users employ the same number of antennas and the channels between any two users are of the same fading statistics. Finally, the impact of nonzero channel means and/or correlation on DMT is evaluated. It is revealed theoretically that the DMTs depend on the number of antennas at each user, channel means (except for Rayleigh and Rician fading statistics), transmit and/or receive correlation, and the polynomial behavior near zero of the channel gain probability density function. Examples are also provided to illustrate the analysis and results.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.3 no.4
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• pp.49-69
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• 2010

In this paper, we propose a class of spectrum sensing schemes for cognitive radio with receive diversity. By considering the generalized likelihood ratio test detector in each branch and exploiting non-linear diversity combining strategy, the proposed scheme exhibits reasonable performance for spectrum sensing even in the environment of heavier-tailed noise. From the results of analysis and computer simulations, it is observed that the proposed scheme provides significant performance gain and performance stability over the conventional schemes, especially in impulsive noise environment.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.15 no.3
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• pp.1156-1173
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• 2021

In this paper, we propose a new joint precoder and postcoder design strategy to support multiple streams per user in multiuser multiple-input multiple-output (MIMO) systems. We propose two step precoding strategies using equal channel gain decomposition and block diagonalization at the transmitter. With the proposed precoder, the multiuser MIMO channel can be decomposed into multiple parallel channels with equal channel gain per user. After applying receive postcoder which is generated and sent by the transmitter, we can use ML based decoder per stream to achieve full receive diversity. Achievable sum rate bound and diversity performance of the proposed algorithm are presented with feedback signaling design and quantitative complexity analysis. Simulation results show that the proposed algorithm asymptotically approaches to the sum rate capacity of the MIMO broadcast channel while maintaining full diversity order.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.4A
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• pp.302-308
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• 2009

In this paper, two receive diversity combining techniques are proposed for single-carrier Sequency division multiple access (SC-FDMA)-based cooperative relay systems when DFT spreading sizes for mobile station (MS) and relay station (RS) are different. A simplified-MRC (5-MRC) technique performs diversity combining in the time domain using the estimated channel weight and initial values obtained by SC-FDMA signal detection. An interference rejection-MRC (IR-MRC) technique performs diversity combining in the frequency domain by adjusting DFT spreading size in the receiver. It is shown by computer simulation that the proposed receive diversity combining techniques achieve a significant performance gain over the conventional MRC technique with zero forcing (ZF) detector.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.8B
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• pp.1348-1356
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• 2000

In this paper, we proposed a trellis coded Multi-Carrier CDMA 16 QAM system with multiple transmit/receive antenna diversity technique, which is simple and suitable for indoor wireless communications. The proposed multiple transmit/receive antenna diversity technique is that the transmitter sends a trellis coded Multi-Carrier CDMA 16 QAM signal from multiple transmitting antennas with intentional time delays, which makes a receiver possible to distinguish and combine the signals from different antennas. In wireless indoor communication system, if we allow the increase of the complexity of the system, it is also possible to achieve additional diversity gain in the performance with the combination of the proposed technique and the conventional receiving antenna diversity. Furthermore, we have found that the proposed trellis coded Multi-Carrier CDMA 16 QAM system, which employs multiple transmit/receive antenna, is less sensitive to the multiple user interference and fading than conventional receiving antenna diversity systems.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.3
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• pp.355-362
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• 2003

In this paper, we analyzed the DS/CDMA System with Hybrid SC/MRC diversity, as a method to achieve a good performance by reducing the complexity of system, when PLL gain value was revised a phase gulf among branches to make perfect coherent receive signal. The channel is a multipath Nakagami-m fading channel, we consider user(K), processor gain(N), number of paths(Lp) in DS/CDMA system with hybrid SC/MRC diversity. We found that PLL gain values exist to make perfect coherent receive signal. We verified that DS/CDMA system with Hybrid SC/MRC diversity can improve performance when the proper PLL gain values is used in the system. As a result, we verified that the upper limit of PLL gain value is 5dB to make perfect coherent receive signal in the DS/CDMA system with hybrid SC/MRC diversity.