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Proceedings of the Global Communications Conference, 2010. GLOBECOM 2010, 6-10 December 2010, Miami, Florida, USA; 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 the 71st IEEE Vehicular Technology Conference, VTC Spring 2010, 16-19 May 2010, Taipei, Taiwan; 01/2010
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ABSTRACT: Focusing on high order multiple-input multiple-output (MIMO) systems, this paper presents an orthogonal grouping-based near optimal detection algorithm (OGNO). Compared to existing detection algorithms, the proposed algorithm provides a new viewpoint of reducing the receiver detection complexity in high order MIMO systems. With the proper parameters, the OGNO can achieve the almost same performance as the optimal maximum likelihood detection (MLD) algorithm but much lower complexity. Meanwhile, the fixed computational complexity offers a practical real-time hardware implementation. The advantage of complexity reduction comes from the orthogonal grouping, which can convert a higher order MIMO system into several lower order MIMO systems, where each subsystem can also be viewed a group. These groups perform detection separately. Due to more than one candidate sequence output from each group, the overall optimal sequence is obtained through ranking combination static group search. The bit error performance evaluation of the proposed algorithm is given by computer simulation and its complexity is evaluated by measuring the total number of floating-point operations (flops). Furthermore, it will be implemented into our real-time FGPA 8Ã8 MIMO-OFDM test-bed and the results from RF experiments will be given in the future.
Personal, Indoor and Mobile Radio Communications, 2009 IEEE 20th International Symposium on; 10/2009
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IEICE Transactions. 01/2009; 92-B:254-267.
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Proceedings of the Global Communications Conference, 2009. GLOBECOM 2009, Honolulu, Hawaii, USA, 30 November - 4 December 2009; 01/2009
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Proceedings of the Global Communications Conference, 2009. GLOBECOM 2009, Honolulu, Hawaii, USA, 30 November - 4 December 2009; 01/2009
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Proceedings of the 70th IEEE Vehicular Technology Conference, VTC Fall 2009, 20-23 September 2009, Anchorage, Alaska, USA; 01/2009
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ABSTRACT: Multiple-input multiple- output (MIMO) and orthogonal frequency division multiplexing (OFDM) are two key techniques for broadband wireless mobile communications. In order to provide accurate channel state information (CSI) to support MIMO-OFDM transmission in doubly-selective fading channels, we propose the robust channel estimator based on two-dimensional enhanced discrete-time Fourier transform interpolation (2D-EDFTI), which needs no channel statistics and can improve the channel estimation accuracy significantly. In order to validate its performance in practice, we implement it into our real-time FPGA testbed of 4-by-4 MIMO-OFDM. Also, channel estimator based on two-dimensional linear interpolation (2D-LI) is implemented for comparison. Experiments demonstrate that our proposed 2D-EDFTI channel estimator is robust to doubly-selective fading channels and its performance is always superior to 2D-LI channel estimator. Therefore, MIMO-OFDM transmission by spatial multiplexing with different kinds of MIMO detector, i.e., zero-forcing (ZF) and dynamic layer-ordering m-path detection (DOM), can be well supported.
Communications, 2008. APCC 2008. 14th Asia-Pacific Conference on; 11/2008
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ABSTRACT: This paper proposes a novel preamble structure and a timing synchronization method for OFDM systems. The preamble structure has both properties of delayed and symmetric correlations which can afford accurate time and frequency synchronization simultaneously. A new timing metric is also proposed according to the preamble structure, which is the production of the modulus of delayed and symmetric correlation profiles. The proposed algorithm has been implemented with FPGA in MIMO-OFDM testbed. The measured timing performances are well accordance with the simulation results. The timing performance is very accurate when SNR is larger than 5 dB, that the probability of timing shift compared to the first path less than 10 samples is above 99.5% in 3GPP case 2 channel. And the timing shifts only distribute on several discrete positions. Furthermore, the timing synchronization can work well in high mobility environment up to 500 km/h.
Communications, 2008. APCC 2008. 14th Asia-Pacific Conference on; 11/2008
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ABSTRACT: During the past decade, multiple-input-multiple-output (MIMO) systems have received a significant attention because of its promising capacity increase over single-input-single-output (SISO) systems. In this paper, as a key technology, we present a novel M-paths MIMO detection algorithm with dynamic-layer-ordering for spatial-multiplexing MIMO systems over rich scattering wireless environment. This algorithm obtains a near-ML detection performance (e.g., only 0.2 dB performance degradation for 4-TX and 4-RX MIMO with 16 QAM) with a much lower computational complexity compared to the ML detection. We also develop an recursive procedure for dynamic-layer-ordering and reduce the ordering complexity from O(N<sub>T</sub> <sup>4</sup>) to O(N<sub>T</sub> <sup>3</sup>), where N<sub>T</sub> is the number of TX antennas. In order to verify the feasibility and performance, a pipelined structure is designed and implemented in FPGA with limited hardware resources and a 200 Mbps throughput.
Communications, 2008. APCC 2008. 14th Asia-Pacific Conference on; 11/2008
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Proceedings of the IEEE 19th International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC 2008, 15-18 September 2008, Cannes, French Riviera, France; 01/2008
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Proceedings of the 67th IEEE Vehicular Technology Conference, VTC Spring 2008, 11-14 May 2008, Singapore; 01/2008
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Proceedings of the 68th IEEE Vehicular Technology Conference, VTC Fall 2008, 21-24 September 2008, Calgary, Alberta, Canada; 01/2008
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Proceedings of the 68th IEEE Vehicular Technology Conference, VTC Fall 2008, 21-24 September 2008, Calgary, Alberta, Canada; 01/2008
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Proceedings of the 68th IEEE Vehicular Technology Conference, VTC Fall 2008, 21-24 September 2008, Calgary, Alberta, Canada; 01/2008
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ABSTRACT: Traditional discrete Fourier transform (DFT) based channel estimation will suffer from significant performance degradation due to the edge effect in practical orthogonal frequency division multiplexing (OFDM) systems with virtual subcarriers. In this paper, a novel enhanced DFT-based channel estimation method is proposed, which can effectively mitigate the edge effect caused by virtual subcarriers via edge value repetition in the frequency domain and zero insertion in the time domain, thus to improve the overall channel estimation performance for the usable subcarriers. Moreover, it does not need a priori statistical characteristics of the wireless channel and the complexity of channel estimation is not increased. Therefore, it is especially suitable for hardware implementation.
Personal, Indoor and Mobile Radio Communications, 2007. PIMRC 2007. IEEE 18th International Symposium on; 10/2007
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Proceedings of the International Conference on Wireless Communications and Mobile Computing, IWCMC 2007, Honolulu, Hawaii, USA, August 12-16, 2007; 01/2007
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ABSTRACT: Channel state information (CSI) is critical for the performance of orthogonal frequency division multiplexing (OFDM) systems. In this paper, we propose time-domain minimum mean square error (MMSE) channel estimation based on subspace tracking for OFDM systems, which can increase the channel estimation accuracy as well as lower the computational complexity. Furthermore, it requires little prior channel statistical information and can track the time-varying wireless channel effectively. With proper training sequences design on transmitter antennas, it can be easily applied to multiple inputs multiple outputs (MIMO) OFDM systems. Computer simulations demonstrate its good performance
Vehicular Technology Conference, 2006. VTC 2006-Spring. IEEE 63rd; 06/2006
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Proceedings of the IEEE 17th International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC 2006, 11-14 September 2006, Helsiniki, Finland; 01/2006
