We consider several hybrid ARQ (H-ARQ) control schemes for high speed downlink packet access (HSDPA) with 16 symbols quadrature amplitude modulation (16QAM). These schemes consist of a sequence of values for the X/sub...
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We consider several hybrid ARQ (H-ARQ) control schemes for high speed downlink packet access (HSDPA) with 16 symbols quadrature amplitude modulation (16QAM). These schemes consist of a sequence of values for the X/sub rv/ parameter to be used at sequential retransmissions when a block is not decoded correctly. A choice of an H-ARQ control scheme influences two parameters: quality of service (QoS) and user equipment (UE) buffer requirements. Based on several link level simulations, we propose an optimal control scheme using maximum space, as well as two slightly suboptimal ones that allow to reduce the UE buffer size.
In this paper, 8-ary Elliptical Phase Shift Keying (8EPSK) Trellis-Coded modulation and set partitioning based on the sum of soft metric distance are proposed and developed. The criterion to design and search for good...
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In this paper, 8-ary Elliptical Phase Shift Keying (8EPSK) Trellis-Coded modulation and set partitioning based on the sum of soft metric distance are proposed and developed. The criterion to design and search for good TCM codes is also presented. The performance of 8EPSK-TCM has been evaluated through Matlab simulation in terms of BER. The results show that the performance of 8EPSK-TCM outperforms the conventional 8PSK-TCM and 8EPSK convolutional codes.
The performance of quasi-synchronous CDMA (QS-CDMA) system, which can allow an increased timing error in synchronized access, is discussed. The QS-sequences are selected from an M-sequence set or a Gold-sequence set c...
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The performance of quasi-synchronous CDMA (QS-CDMA) system, which can allow an increased timing error in synchronized access, is discussed. The QS-sequences are selected from an M-sequence set or a Gold-sequence set considering the cross-correlation property, and the average BER is calculated for the system with QS-sequences. As a result, the average BER of the system with QS-sequences is improved considerably compared with asynchronous CDMA when the access timing error is within a few chip durations.< >
Space-Time coding and MIMO wireless systems are two recent technological breakthroughs in modern communications. The promises of information theoretic MIMO analysis has ignited the study of related areas such as MIMO ...
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Space-Time coding and MIMO wireless systems are two recent technological breakthroughs in modern communications. The promises of information theoretic MIMO analysis has ignited the study of related areas such as MIMO channel modeling, Space-Time coding, Space-Time signal processing, etc. One of the most popular models because of its simplicity is the Kronecker mode1. In this paper we analyze the Alamouti coding scheme and study the impact of antenna correlation for this scheme using BPSK modulation and a 2 x 2 MIMO channeI. The MIMO Kronecker model was used in the simulation for various spatial correlation factors and the associated Doppler shifts in each branch. The results in this paper are new in this context and have not been found elsewhere.
Two techniques for deriving the power spectral density (PSD) of digitally modulated signals are examined. Both concentrate on the autocorrelation function of modulated sequences, and one of them makes use of the discr...
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Two techniques for deriving the power spectral density (PSD) of digitally modulated signals are examined. Both concentrate on the autocorrelation function of modulated sequences, and one of them makes use of the discrete Fourier transform coefficients of this function. These methods provide general expression for PSDs which can be useful in a variety of situations; for example, in the case of the product pseudonoise (PN) codes with arbitrary modulating waveforms. Specific examples are given, where the dependence of the PSD on the relative shift between the two versions of a PN sequence is demonstrated. This could have implications on all systems which use the standard correlation operation (despreading) of PN codes and different pulse shapes.< >
In this paper, we consider the uplink of a coded MIMO-OFDM multiuser system with transmitting precoding in frequency-selective fading channels, where the transmitters (user) as well as the receiver (base station) are ...
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ISBN:
(纸本)0780390156
In this paper, we consider the uplink of a coded MIMO-OFDM multiuser system with transmitting precoding in frequency-selective fading channels, where the transmitters (user) as well as the receiver (base station) are equipped with multiple antennas. Each user's information bit sequence is independently encoded by a turbo encoder, spatial multiplexed and then spread by orthogonal Walsh code (OWC), interleaved, linear precoded, OFDM modulated and transmitted through its transmit antennas. At the receiver, we combine interference cancellation (IC) detection of multiple antennas and multiuser and turbo decoding to form a system iterative feedback structure, which jointly optimizes and improves the performance of detection and decoding. In this paper, we also consider a scheme for transmitting linear precoding to balance the complexity of transmitter and receiver and help to improve the ability of IC detection. Through computer simulation results, we verify the system performance in frequency-selective fading channels.
Direct-sequence spread-spectrum (DS/SS) system has been extensively studied for land mobile communications because of the notable and attractive features such as its robustness and applicability to code division multi...
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Direct-sequence spread-spectrum (DS/SS) system has been extensively studied for land mobile communications because of the notable and attractive features such as its robustness and applicability to code division multiple access (CDMA). We propose a DS/SS modulation method which employs Gaussian-filtered minimum-shift-keying (GMSK) and permits simple code acquisition. The modulated signal can be demodulated by a four-phase correlator which can obtain the correlation value of the received signal even if a phase difference between the transmitter and the receiver exists. The bit error performance obtained by the hardware experiments ensures the validity of this modulation method.
A serially concatenated system with DUSTM (differential unitary space-time modulation) as an inner code and LDPC (low density parity check codes) as outer code is proposed. And a combined iterative soft decoding algor...
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A serially concatenated system with DUSTM (differential unitary space-time modulation) as an inner code and LDPC (low density parity check codes) as outer code is proposed. And a combined iterative soft decoding algorithm is presented based on serially concatenated structure and turbo principle. This proposed scheme outperforms the trellis coded DUSTM scheme studied previously for the usage of good LDPC codes and the combined iterative decoding algorithm.
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