By Topic

Joint sequential channel estimation and multiuser detection for uplink CDMA over multipath fading

Sign In

Cookies must be enabled to login.After enabling cookies , please use refresh or reload or ctrl+f5 on the browser for the login options.

Formats Non-Member Member
$31 $13
Learn how you can qualify for the best price for this item!
Become an IEEE Member or Subscribe to
IEEE Xplore for exclusive pricing!
close button

puzzle piece

IEEE membership options for an individual and IEEE Xplore subscriptions for an organization offer the most affordable access to essential journal articles, conference papers, standards, eBooks, and eLearning courses.

Learn more about:

IEEE membership

IEEE Xplore subscriptions

3 Author(s)
Qinghua Li ; Intel Corp., Santa Clara, CA, USA ; Georghiades, C.N. ; Xiaodong Wang

We consider joint channel estimation and data detection in uplink asynchronous CDMA systems employing aperiodic (long) spreading sequences in the presence of unknown multipath fading. Since maximum-likelihood sequence estimation is too complex to perform, multiuser receivers are proposed based on the sequential expectation-maximization (EM) algorithm. With prior knowledge of only the signature waveforms, the delays and the second-order statistics of the fading channel, the receivers sequentially estimate the channel using the sequential EM algorithm. The snapshot estimates of each path are further tracked by linear minimum-mean-squared-error (MMSE) filters and the user data are detected by a maximum-likelihood sequence detector, given the channel estimates. The proposed receivers that use the exact expressions have a computational complexity O(2K) per bit, where K is the number of users. Using the traditional EM algorithm, we derive low-complexity approximations which have a complexity of O(K2) per bit. Simulation results demonstrate that the proposed receivers offer substantial performance gains over conventional pilot-symbol assisted techniques and achieve a performance close to the known-channel bounds. Furthermore, the proposed receivers even outperform the single-user RAKE receiver with Nyquist pilot-insertion rate in a single-user environment.

Published in:

Vehicular Technology Conference, 2002. Proceedings. VTC 2002-Fall. 2002 IEEE 56th  (Volume:3 )

Date of Conference:

2002