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ABSTRACT: We provide some examples of our proposed APSK constellations in this technique report, whereby the mutual information between the channels' inputs and outputs associated with such APSK constella-tions is also presented. Results show that well-designed APSK constellations according to our procedure have indistinguishable mutual information at low-to-median SNR, while the mutual information at high SNR is dominated by the minimum Euclidean distance between adjacent constellation points.
Technical Report; 08/2012
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ABSTRACT: It has been widely believed that phased array antenna should use at least 3-bit (as phase controlling bit) phase shifter to
provide the satisfactory scanning capability and the unnoticeable parasitic sidelobes. In this paper, we proposed a novel
phase perturbation method, namely, virtual feed approach, derived from the general concept of the phase randomization, to
improve the performance for the low-cost electronic scanning antennas with 2-bit phase shifters. By using this method, problems
of scanning error at small scanning angle as well as the relatively high parasitic sidelobes at large scanning angle are solved
simultaneously at acceptable performance degradation.
Wireless Personal Communications 04/2012; 52(1):29-41. · 0.46 Impact Factor
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ABSTRACT: The simple differential designs on both space-time coded OFDM (STC-OFDM) and space-frequency coded OFDM (SFC-OFDM) are introduced
when neither the transmitter nor the receiver has the channel state information. In the differential STC-OFDM (DSTC-OFDM)
and the differential SFC-OFDM (DSFC-OFDM) systems, the block differential encodings are adopted in the time dimension and
the frequency dimension, respectively. We give the detailed description and theoretical analysis of the two schemes. The effectiveness
in achieving the transmitter diversity is illustrated by simulations in both slow and fast fading environments. By taking
the advantage of the characteristics of the OFDM frame structure, the computational complexity of the introduced schemes is
greatly reduced.
Wireless Personal Communications 04/2012; 52(1):195-208. · 0.46 Impact Factor
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ABSTRACT: In the conventional digital television terrestrial multimedia broadcasting (DTMB) systems, all the transport streams (TS) from various programs are multiplexed in the level of TS packets, which have the same interleaving, constellation mapping, channel coding, and thus the same quality of service (QoS). Moreover, due to the convolutional interleaving mode, the receivers have to be turned on all the time to obtain the designated data until all the received signals are de-interleaved. In this paper, for DTMB systems, the concept of the physical sub-channel (PSC) in time-frequency domain is proposed, and the scheme to support services with different QoS requirements is also addressed. Based on these techniques, a novel approach to support multimedia services over DTMB systems in a backward compatible manner is proposed and evaluated by computer simulations.
IEEE Transactions on Broadcasting 10/2011; · 1.70 Impact Factor
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ABSTRACT: The state-of-the-art time domain synchronous OFDM (TDS-OFDM) transmit diversity schemes are only suitable either for fast time-varying but weakly frequency-selective channels, or deeply frequency-selective but slowly time-varying channels. In this paper, a novel TDS-OFDM transmit diversity scheme based on the space-time shifted constant amplitude zero autocorrelation (CAZAC) sequence is proposed over doubly selective broadcasting channels. The space-shifted CAZAC sequence is used for the unbiased maximum likelihood (ML) channel estimation. The time-shifted sequence is utilized for the low-complexity cyclicity reconstruction of the received inverse discrete Fourier trans form (IDFT) block. Compared with the existing solutions, the signal-to-noise ratio (SNR) gain of about 2.5 dB can be achieved by the proposed scheme at the uncoded bit error rate (BER) of 10<sup>-2</sup> over the deeply frequency-selective single frequency network (SFN) broadcasting channel when the receiver velocity is 140 km/h, at the cost of the spectral efficiency penalty of about 2.88%.
IEEE Transactions on Broadcasting 04/2011; · 1.70 Impact Factor
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ABSTRACT: Time domain synchronous OFDM (TDS-OFDM) with higher spectral efficiency than cyclic prefix OFDM (CP-OFDM)was originally proposed for downlink broadcasting transmission. To support multi-user uplink scenarios, this paper proposes a novel multiple access scheme called time domain synchronous frequency division multiple access (TDS-FDMA), wherein an uniform frame structure and its corresponding receiver algorithms are presented for both single-carrier and multicarrier signal transmission. Compared with typical OFDMA systems, TDS-FDMA has higher spectral efficiency. The multi-user TDS-FDMA receiver has lower complexity than the conventional single-user TDS-OFDM receiver, and it can achieve better bit error rate (BER) performance under the slow to medium time-varying channels.
Global Telecommunications Conference (GLOBECOM 2010), 2010 IEEE; 01/2011
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IEEE ISIT; 01/2011
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IEICE Transactions. 01/2011; 94-B:1118-1121.
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IEICE Transactions. 01/2011; 94-B:282-284.
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IEICE Transactions. 01/2011; 94-B:793-795.
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IEICE Transactions. 01/2011; 94-B:1472-1475.
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ABSTRACT: Labeling is crucial for bit-interleaved coded modulation with iterative demapping and decoding (BICM-ID) systems. Based on extrinsic information transfer (EXIT) charts, a novel adaptive binary switch algorithm (ABSA) in searching for labeling to well match the outer channel code is proposed. ABSA can be applied to arbitrary constellations, meanwhile it makes the proposed BICM-ID systems hold a near-capacity performance.
IEEE Communications Letters 12/2010; · 0.98 Impact Factor
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ABSTRACT: By adopting the pseudo-random noise (PN) sequences as the guard interval (GI) as well as the training sequence, time domain synchronous orthogonal frequency division multiplexing (TDS-OFDM) outperforms the conventional OFDM using the cyclic prefix (CP) in the spectral efficiency at the cost of the iterative padding subtraction (IPS) in channel estimation (CE). To avoid the high computational complexity of the IPS, an improved frequency domain CE scheme based on a newly designed frame structure is proposed. To further improve the CE accuracy, the time domain training sequences, which are frequency binary (FB) after the fast Fourier transform (FFT), are flexibly padded as the frame header instead of the PN sequences. Theoretical analyses and computer simulations show that the proposed scheme can improve the system performance under the time frequency doubly selective channels, even in the presence of large channel delays in the single frequency networks.
IEEE Transactions on Broadcasting 10/2010; · 1.70 Impact Factor
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ABSTRACT: Single carrier frequency division multiple access (SC-FDMA) is one well-known scheme, which has recently become a preferred choice for uplink channels. Due to the usage of single carrier, the performance of SC-FDMA systems degrades in deep frequency selective fading channels. In this paper, we propose a structure of equalizer based on frequency domain decision feedback which could be used for multi-user SC-FDMA systems. Specific parameters of the equalizer are analyzed as well. This algorithm is applicable to various carrier allocations in multi-user systems such as localized allocation, distributed allocation, and frequency-hopping (FH) allocation. To reduce the complexity, it is not necessary to derive the inversion of matrix, which is required in the traditional decision feedback equalizer for single carrier frequency domain equalization (SC-FDE-DFE). It is shown by the simulation results that perfect performance could be achieved under all kinds of situations for multi-user systems. This structure can be used in the broadcasting uplink channels with SC-FDMA scheme.
IEEE Transactions on Broadcasting 07/2010; · 1.70 Impact Factor
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ABSTRACT: A carrier frequency offset estimation algorithm based on Pseudo-random Noise (PN) sequence correlation property is presented in this paper. Correlation peaks of the whole sequence and segment sequence are obtained respectively. Their ratio is used to develop a closed-form solution to frequency offset estimation in a certain range and acquire frequency in a bigger scope. Frequency offset estimation may be completed by one PN training sequence or two identical sequences and the algorithm is suitable to use in extensive situations.
Wireless Mobile and Computing (CCWMC 2009), IET International Communication Conference on; 01/2010
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ABSTRACT: To improve the overall performance of time-domain synchronous (TDS) orthogonal frequency division multiplexing (OFDM) systems, novel iterative decoding and channel estimation algorithm with Nordstrom-Robinson (NR) code is proposed in this paper. Compared to the non-iterative case, the system performance can be significantly improved by the proposed iterative algorithm at the cost of a little complexity and latency increase. Simulation results show that, for example, with maximum Doppler spread of 25 Hz under two typical multipath channels at bit error rate (BER) of 10<sup>-4</sup>, the signal to noise ratio (SNR) performance of the proposed iterative algorithm is only 0.2 to 0.3 dB away from the ideal case, and about t dB or more better than the non-iterative one.
Global Telecommunications Conference, 2009. GLOBECOM 2009. IEEE; 01/2010
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Proceedings of the 6th International Wireless Communications and Mobile Computing Conference, IWCMC 2010, Caen, France, June 28 - July 2, 2010; 01/2010
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Proceedings of the 72nd IEEE Vehicular Technology Conference, VTC Fall 2010, 6-9 September 2010, Ottawa, Canada; 01/2010
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Proceedings of IEEE International Conference on Communications, ICC 2010, Cape Town, South Africa, 23-27 May 2010; 01/2010
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IEICE Transactions. 01/2010; 93-B:207-210.
