Time filter

Source Type

Guangzhou, China

Hou W.,University of Western Ontario | Jiang M.,New Postcom Equipment Co.
IEEE Signal Processing Letters | Year: 2012

In amplify-and-forward (AF) type relaying assisted orthogonal frequency division multiplexing (OFDM) systems, channel estimation (CE) is a challenging task due to the increased frequency selectivity caused by the cascaded source-to-relay-to-destination $(S\rightarrow R\rightarrow D)$ multipath channel. Typically, such cascaded channels result in severe time dispersion. Consequently, it requires additional pilot overhead for CE as well as longer cyclic prefix (CP) for eliminating the inter-symbol interference (ISI), which will inevitably reduce the achievable diversity provided by cooperative transmissions. In this letter, a three-step CE scheme is proposed without the need of increasing pilot overhead. Furthermore, by reconstructing the CP at the relay node, the CP length does not necessarily need to be extended for the cascaded channel. Simulation results demonstrate the effectiveness of our proposed scheme even in severely time-dispersive multipath fading channels. © 1994-2012 IEEE.

Ke F.,South China University of Technology | Geng H.-X.,South China University of Technology | Feng S.-L.,South China University of Technology | Jiang M.,New Postcom Equipment Co.
Huanan Ligong Daxue Xuebao/Journal of South China University of Technology (Natural Science) | Year: 2012

Proposed in this paper is an opportunistic relaying strategy for decoding-and-forwarding wireless cooperative relay networks based on power weighting. In this strategy, the power weight is determined according to the residual energy of each node in the network, and the optimal cooperative relay of each source node is selected according to the minimum weighted-energy criterion. Moreover, the optimal power allocation between the source node and the relay node is obtained via the simplex method. Thus, the energy utilization is improved and the energy consumption of each node in the network is balanced. Simulated results show that the proposed strategy is superior to other strategies in terms of prolonging the lifetime of cooperative relay networks.

Hou W.,University of Western Ontario | Jiang M.,New Postcom Equipment Co.
IEEE Communications Letters | Year: 2013

This letter presents an enhanced joint channel and in-phase and quadrature-phase (IQ) imbalance parameter estimation method for communication systems. The proposed method first estimates the channel impulse response (CIR) with integrated IQ imbalance parameters, which contains twice the number of the original CIR parameters. To exploit the additional redundancy in the initial estimate, the alternating least square (ALS) algorithm is used to estimate the channel and the IQ imbalance parameters in an iterative manner. Particularly, the proposed method can exploit the beneficial linear structure of the initial estimate and largely reduce the required number of the estimated parameters, thereby enhancing the estimation performance. Simulation results demonstrate the efficacy of our proposed scheme in multipath fading channels even with severe IQ imbalance impairments. © 1997-2012 IEEE.

Wen W.,New Postcom Equipment Co. | Xia M.,University of Hong Kong | Wu Y.-C.,University of Hong Kong
IEEE Transactions on Wireless Communications | Year: 2010

The zero-padded block transmission with linear time-domain pre-equalizer is studied in this paper. A matched filter is exploited to guarantee the stability of the zero-forcing (ZF) and minimum mean square error (MMSE) pre-equalization. Then, in order to compute the pre-equalizers efficiently, an asymptotic decomposition is developed for the positive-definite Hermitian banded Toeplitz matrix. Compared to the direct matrix inverse methods or the Levinson-Durbin algorithm, the computational complexity of the proposed algorithm is significantly decreased and there is no bit error rate degradation when data block length is large. © 2010 IEEE.

Jiang M.,New Postcom Equipment Co. | Hanzo L.,University of Southampton
IEEE Signal Processing Letters | Year: 2010

Linear Dispersion Codes (LDCs) have recently attracted numerous research interests. Thanks to their efficient spreading of data across both the time and spatial domains, LDCs are capable of achieving a desired Diversity-Multiplexing Trade-off (DMT) in Multiple Input Multiple Output (MIMO) broadband wireless access systems. This paper proposes a novel LDC design method, which relies on the unitary matrix theory combined with a Genetic Algorithm (GA) aided optimization procedure. The proposed design provides a flexible framework, where new LDCs attaining higher data rates and better error resilience than a number of classic MIMO schemes can be generated. © 2010 IEEE.

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