Chi Hieu Ta

A Design of Precoding and Equalisation for Broadband MIMO Systems

We propose a new approach to precoding and equalisation for frequency selective MIMO channels by applying a recently proposed broadband singular value decomposition to decouple the MIMO channel matrix into independent frequency selective SISO subchannels. In a second step, ISI present in the subchannels is eliminated using methods reported in the literature. The first step helps to remove not only co-channel interference but also eliminates part of the inter-symbol interference with a very small loss in channel power gain. It also helps to use the system resource more effectively, leading to a better performance. The numerical example given in the paper shows that our proposed method can provide better bit error rate performance than that of the benchmark design. Under a quality of service constraint, our design can achieve higher data throughput and mutual information than that of the benchmark design while maintaining a similar error performance.

Shortening the order of paraunitary matrices in SBR2 algorithm

The second order sequential best rotation (SBR2) algorithm has recently been proposed as a very effective tool in decomposing a para-Hermitian polynomial matrix R(z) into a diagonal polynomial matrix T(z) and a paraunitary matrix B(,z), extending the eigenvalue decomposition to polynomial matrices, R-(z) = B(z)T(z)~B(z). However, the algorithm results in polynomials of very high order, which limits its applicability. Therefore, in this paper we evaluate approaches to reduce the order of the paraunitary matrices, either within each step of SBR2, or after convergence. The paraunitary matrix B(z) is replaced by a near-paraunitary quantity BN(z), whose error will be assessed. Simulation results show that the proposed truncation can greatly reduce the polynomial order while retaining good near-paraunitariness of BN(z).

Broadband SVD and non-linear precoding applied to broadband MIMO channels

We address the problem of precoding and equalisation of broadband MIMO systems. A new non-block based methods is based on a broadband singular value decomposition, which can decouple a broadband MIMO channel into independent dispersive SISO subchannels. We thereafter apply Tomlinson-Harashima precoding to mitigate the dispersiveness of these SISO subchannels. We present arguments why this is a suitable approach compared to existing methods, underlined by some simulation results.

Joint Precoding and Equalisation Design Using Oversampled Filter Banks for Dispersive Channels with Correlated Noise

Oversampled filter banks (OSFBs) have recently been considered for channel coding since their redundancy introduced into the transmitted signal permits more freedom in the design of joint transmitter and receiver. Further specifically, they can be exploited to transmit over low noise subspaces or even mitigate dispersiveness of the channel. In this paper we propose a joint precoding and equalisation design using OSFBs, which find a compromise between transmitting over the low-noise subspace of channel noises polyphase components, and the high-gain subspace of the channels polyphase components. Polynomial building blocks are permitted and the minimisation of the mean square error (MSE) at the receiver output is achieved. We describe the design, and highlight the communalities and differences of this approach to existing methods. Simulation results show the benefit of the proposed system design compared to existing design approaches.

An approach for block transmission based precoding and equalisation with improved performance

Block transmission is very efficient method to combat with inter-symbol interference. However, the way it uses the guard intervals reduces spectral efficiency of the system. In this paper, we propose a new approach to block transmission based precoding and equalisation for frequency selective channels. Different with standard block transmission schemes, our method employs redundancy in a different way so that the channel energy can be better employed, thus leading to improved performance under the same code rate.