Optimal Design of Noisy Transmultiplexer Systems
- PDF / 426,978 Bytes
- 8 Pages / 600.03 x 792 pts Page_size
- 33 Downloads / 208 Views
Optimal Design of Noisy Transmultiplexer Systems Huan Zhou1 and Lihua Xie2 1 Signal 2 School
Processing Group, Institute of Physics, University of Oldenburg, 26111 Oldenburg, Germany of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 639798
Received 31 October 2004; Revised 26 August 2005; Accepted 19 September 2005 Recommended for Publication by Yuan-Pei Lin An optimal design method for noisy transmultiplexer systems is presented. For a transmultiplexer system with given transmitters and desired crosstalk attenuation, we address the problem of minimizing the reconstruction error while ensuring that the crosstalk of each band is below a prescribed level. By employing the mixed H2 /H∞ optimization, we will ensure that the system with suboptimal reconstruction error is more robust and less sensitive to the changes of input signals and channel noises. Due to the overlapping of adjacent subchannels, crosstalk between adjacent channels is expected. And the problem of crosstalk attenuation is formulated as an H∞ optimization problem, solved in terms of linear matrix inequalities (LMIs). The simulation examples demonstrate that the proposed design performs better than existing design methods. Copyright © 2006 Hindawi Publishing Corporation. All rights reserved.
1.
INTRODUCTION
Transmultiplexers (TMUX) were studied in the early 1970’s by Bellanger and Daguet [1] for telephone applications, with original intention to convert data between time division multiplexed (TDM) format and frequency-division multiplexed (FDM) format. They have been successfully utilized for multiuser communications. A multi-input multi-output (MIMO) M-band conventional TMUX system (Figure 1) with critical sampling (i.e., all interpolation factors equal to band number, also called as minimally interpolated TMUX in [2]) is well suited for simultaneous transmission of many data signals through a single channel by using the frequency-division multiplexing (FDM) technique. In traditional distortion-free (C(z) = 1 and r(n) = 0 in Figure 1) TMUX system, the transmitters (the left filter bank) {Fi (z)} traditionally cover different uniform regions of frequency. So the signals ui (n), i = 0, 1, . . . , M − 1, are packed into M adjacent frequency bands (passbands of the filters) and added to obtain the composite signal q(n). With the transmitters Fi (z), i = 0, 1, . . . , M − 1, chosen as ideal bandpass filters, we can regard p(n) as a frequency-division multiplexed or FDM version of the separate signals ui (n), and the receivers (the right filter bank) {Hk (z)} decompose this signal into vi (n), i = 0, 1, . . . , M − 1, with the decimated version of vi (n) being the reconstructed signal si (k). So, the TMUX system can be seen as a complete TDM → FDM → TDM converter which is exactly the dual system of the subband filter bank system [3].
However, in the TMUX system, if the transmitters Fi (z) are nonideal, the adjacent spectra will actually tend to overlap. Similarly, if the receivers Hi (z) are nonideal, then the output
Data Loading...
