-
[show abstract]
[hide abstract]
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
-
[show abstract]
[hide abstract]
ABSTRACT: Signal space diversity (SSD) is a well-known power- and bandwidth-efficient diversity technique with constellation rotation and coordinate interleaving. This paper investigates issues of combining SSD with coded modulation systems (CMSs), e.g., bit-interleaved coded modulation (BICM) and its iterative version, BICM-ID. It demonstrates that the average mutual information (AMI) between the signal after rotated constellation mapping and the signal before or after the soft demapper varies with the rotation angle. A new criterion for determining the optimal rotation angle by maximizing such AMI is therefore proposed. Specific considerations of combining SSD with BICM (BICM-SSD) and BICM-ID (BICM-ID-SSD) are addressed. The demapper's extrinsic information transfer (EXIT) curve in traditional BICM-ID systems exhibits different slopes under different channels, which consequently prevents traditional BICM-ID systems from having simultaneously excellent performance under different channels. It is shown that such a different-slope problem can be simply mitigated by a proper use of SSD. Analysis and simulation show that the proposed BICM-ID-SSD systems hold a near-capacity performance under both additive white Gaussian noise (AWGN) and Rayleigh fading channels simultaneously.
IEEE Transactions on Wireless Communications 03/2011; · 2.59 Impact Factor
-
IEEE ISIT; 01/2011
-
IEICE Transactions. 01/2011; 94-B:282-284.
-
Proceedings of the 7th International Wireless Communications and Mobile Computing Conference, IWCMC 2011, Istanbul, Turkey, 4-8 July, 2011; 01/2011
-
IEICE Transactions. 01/2011; 94-B:2158-2160.
-
Proceedings of the 7th International Wireless Communications and Mobile Computing Conference, IWCMC 2011, Istanbul, Turkey, 4-8 July, 2011; 01/2011
-
IEICE Transactions. 01/2011; 94-A:2027-2030.
-
Proceedings of the 7th International Wireless Communications and Mobile Computing Conference, IWCMC 2011, Istanbul, Turkey, 4-8 July, 2011; 01/2011
-
[show abstract]
[hide abstract]
ABSTRACT: Time domain synchronous orthogonal frequency division multiplex (TDS-OFDM) is an effective multi-carrier modulation scheme to improve the spectrum efficiency. However, conventional synchronization algorithm based on the correlation property of the time-domain pseudo-noise (PN) sequence may not work well over severe multipath fading channels when large carrier frequency offset (CFO) exits. In this paper, a robust synchronization algorithm is proposed where the PN sequence in the frame head is considered as a cyclic prefix (CP) OFDM training symbol. The time-domain slide auto-correlation based on the cyclic structure of the PN sequence is adopted for timing and fine CFO estimation, while in the frequency domain, a differential correlation is applied for large CFO estimation. Simulations demonstrate that the proposed method could achieve the satisfactory performance over multipath fading channels. In addition, to reduce the implementation complexity, the frame head of the TDS-OFDM system is preferred to be binary PN sequences in the frequency domain with cyclic structure in the time domain.
IEEE Transactions on Consumer Electronics 12/2010; · 0.94 Impact Factor
-
[show abstract]
[hide abstract]
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
-
IEICE Transactions. 01/2010; 93-B:3189-3192.
-
Proceedings of the 72nd IEEE Vehicular Technology Conference, VTC Fall 2010, 6-9 September 2010, Ottawa, Canada; 01/2010
-
IEEE Globecom; 01/2010
-
Proc. IEEE Int Broadband Multimedia Systems and Broadcasting (BMSB) Symp; 01/2010
-
[show abstract]
[hide abstract]
ABSTRACT: In order to improve the system performance over both frequency- and time-selective fading channels, orthogonal frequency division multiplexing (OFDM) system with transmit diversity technique is an effective and attractive solution. However, the received signal is the superposition of the signals from different transmit antennas. Hence, to obtain accurate channel state information (CSI) is difficult but very important to recover transmitted OFDM symbols. Conventional channel estimation methods use subcarrier pilots or training sequences as the channel sounding signal to obtain the estimation of channel frequency response (CFR). Actually, decision-directed channel estimation (DDCE) method which takes advantage of the fact that m-QAM constellation subcarriers in OFDM symbol also contain much valuable hidden-information and can be used to perform the channel estimation as well as tracking of time-varying channel. In this paper, a simple and effective partial hard decision method for m-QAM is investigated. Furthermore, a simplified DDCE method based on an accurate initial CFR and partial decision results of OFDM subcarriers for transmit diversity system is proposed. Simulation results demonstrate that the proposed algorithm works well over the slow-varying frequency-selective fading channel.
Vehicular Technology Conference, 2009. VTC Spring 2009. IEEE 69th; 05/2009
-
IEICE Transactions. 01/2009; 92-A:1704-1707.
-
IEICE Transactions. 01/2009; 92-B:1901-1903.
-
IEICE Transactions. 01/2009; 92-B:2308-2311.
-
Proceedings of the 69th IEEE Vehicular Technology Conference, VTC Spring 2009, 26-29 April 2009, Hilton Diagonal Mar, Barcelona, Spain; 01/2009
