A new low-cost discrete bit loading using greedy power allocation

In this paper we consider a low cost bit loading based on the greedy power allocation (GPA). Compared to the standard GPA, which is optimal in terms of maximising the data throughput, three suboptimal schemes are suggested, which perform GPA on subsets of subchannels only. We demonstrate how these schemes can reduce complexity. Two of the proposed algorithms can achieve near optimal performance by including a transfer of residual power between subsets at the expense of a very small extra cost. By simulations, we show that the two near optimal schemes perform best in two separate and distinct SNR regions

Comparison of precoding methods for broadband MIMO systems

In this paper we investigate non-linear precoding solutions for the problem of broadband multiple-input multipleoutput (MIMO) systems. Based on a broadband singular value decomposition (BSVD) we can decouple a broadband MIMO channel into independent dispersive spectrally majorised singleinput single-output (SISO) subchannels. Bit loading is proposed to optimally utilise these SISO subchannels after mitigating their individual inter-symbol-interference (ISI) using Tomlinson- Harashima precoding (THP). This method is benchmarked against recent results of both MMSE linear and THP designed for frequency-selective MIMO channels. Simulation results show that better bit-error-ratio (BER) can be achieved especially for higher throughput targets when compared to the benchmar

Efficient Tomlinson-Harashima precoding ordering using QR decomposition

In this paper, we investigate the effect of precoding ordering on systems with successive interference cancellation for multiple-input multiple-output (MIMO) ,i.e., Tomlinson-Harashima precoding (THP). Based on the well known QR decomposition, a simple precoding ordering scheme based on a per-layer mean square error (M SE) criterion of the diagonal entries of the R-factor is proposed. In addition, an efficient point-to-point communications while in [8,9] transmit feed forward filter is used, allowing point-to-multi-point communications (downlink scenarios) with decentralised and noncooperatives implereceivers

A concurrent blind receiver for STBC over doubly dispersive channels

Space-time block coding (STBC) achieves the maximum diversity gain of a flat fading multiple input multiple output (MIMO) transmission link. For frequency selective fading, only a few receivers can be found in the literature. These are mainly trained and block based, such as time reversal STBC (TRSTBC). A non-block based blind receiver for STBC over dispersive channels has been derived previously, adding a new term to the cost function of the constant modulus algorithm to orthogonalise the outputs. In this paper a decision directed (DD) equalizer is used concurrently with the CMA receiver to achieve faster convergence. Simulation results demonstrate the benefit of the proposed approach in terms of convergence speed and bit error ratio in a doubly-dispersive scenario

An oversampled modulated filter bank transmultiplexer with precoding and equalisation

This paper addresses an oversampled filter bank transmultiplexer applied to a power line commmunications scenario. We proposed structure has a low oversampling ratio and therefore introduces only a small amount of redunancy. Of particular interest are the possibility to iterate the filter bank in order to shorten the overall response, which is traded-off against the use of precoding or equalisation in order to target remaining ISI is only a low number of multiplexed bands are used. However, we demonstrate the iteration of the filter banks does not reduce the problme of timing synchronisation