Noncoherent Decorrelative Multiuser Detection for Nonlinear Nonorthogonal Modulation

<body background="_themes/varhome/hadamard.gif" bgcolor="#FFFFFF" text="#000000" link="#3366CC" vlink="#666666" alink="#FF3300"><font face="trebuchet ms, arial, helvetica">  <p> <a href="http://dsp.colorado.edu"><img src="images/dsplogo.gif" alt="dsplogo.gif (3930 bytes)" border="0" align="middle" WIDTH="153" HEIGHT="50"></a> <a href="http://ece-www.colorado.edu"><img src="_borders/ecebutton.gif" alt="ECE Homepage" align="middle" border="0" WIDTH="63" HEIGHT="56"></a> <a href="http://www.colorado.edu"><img src="_borders/colorado.jpg" alt="University Homepage" align="middle" border="0" WIDTH="91" HEIGHT="54"></a></p> <div align="left"> </font><table border="0" cellpadding="5" cellspacing="0"> <tr> <td width="150" valign="top" align="center"><font face="trebuchet ms, arial, helvetica"><strong><small><small>This paper falls into the Research Interests:</small></small></strong><p> </p> <p><small><a href="res-ncmu.htm" target="main"><strong><small>Noncoherent Multiuser Detecion</small></strong></a></small></font></td> <td valign="top" align="left" width="750"><font face="trebuchet ms, arial, helvetica"><h2><font color="#CC6666">Noncoherent Decorrelative Multiuser Detection for Nonlinear Nonorthogonal Modulation</font></h2> <p>M. K. Varanasi and A. Russ, Proc of the 1997 IEEE Intl Conf Communications, Montreal, Quebec, Canada, June 1997.</p> <p>Coherent multiuser detection for linear modulation has been the subject of intense research in the past decade. Noncoherent detection for linear differentially phase shift keyed modulation has also received much attention in the last few years. This paper considers for the first time the problem of noncoherent detection for M-ary nonlinear nonorthogonal modulation in the Gaussian correlated-waveform multiple-access channel. </p> <p>A key idea proposed here is that of a noncoherent decorrelative front end for nonlinear modulation. Like its counterpart in linear modulation, that front-end eliminates multiuser interference (at the price of noise enhancement) and reduces the multiuser detection problem into that of single-user detection over an equivalent (noise-enhanced) single-user channel. </p> <p>However, the M effective signals of the equivalent single-user channel are correlated and of unequal energy. Noncoherent detection even in this effective single-user channel has been an open problem to date. We derive the optimum detector for this channel. It is unfortunately too complicated to implement or analyze. Two suboptimal detectors are proposed as a result depending on whether knowledge of the energies of the M signals are known or unknown at the receiver. For unknown energies, the generalized likelihood ratio test leads to a detector which is easy to implement. Error probability bounds are obtained for this detector. It is shown to be near-far resistant (in contrast to the conventional detector). For known energies, an asymptotic series expansion of a special function involved in the optimum noncoherent decision rule leads to the other suboptimum detector. Its analysis is more difficult but we nevertheless obtain exact expressions for error probability for binary modulation and bounds on error probability in the M-ary case. This detector can outperform the GLRT detector by a significant margin. Both detectors far outperform the conventional single-user detector.</p> <p><strong><small>This material is presented to ensure timely dissemination of scholarly and technical work. Copyright and all rights therein are retained by authors or by other copyright holders. All persons copying this information are expected to adhere to the terms and constraints invoked by each author's copyright. In most cases, these works may not be reposted without the explicit permission of the copyright holder.</small></strong></p> <p><strong><small>© 2000 <a href="http://www.ieee.org/">IEEE</a>. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the <a href="http://www.ieee.org/">IEEE</a>.</small></strong></p> </font></td> </tr> </table><font face="trebuchet ms, arial, helvetica"> </div> <p><small><small>Last modified: 2000-03-31T22:32</small></small></p>  </font></body>