Long codes for generalized FH-OFDMA through unknown multipathchannels
Shengli Zhou; Giannakis, G.B.; Scaglione, A.
Communications, IEEE Transactions on
Volume 49, Issue 4, Apr 2001 Page(s):721 - 733
Digital Object Identifier 10.1109/26.917778
Summary:A generalized frequency-hopping (GFH) orthogonal
frequency-division multiple-access (OFDMA) system is developed in this
paper as a structured long code direct-sequence code-division
multiple-access (DS-CDMA) system in order to bridge frequency-hopped
multicarrier transmissions with long code DS-CDMA. Through judicious
code design, multiuser interference is eliminated deterministically in
the presence of unknown frequency-selective multipath channels. Thanks
to frequency-hopping, no single user suffers from consistent fading
effects and constellation-irrespective channel identifiability is
guaranteed regardless of channel nulls. A host of blind channel
estimation algorithms are developed trading off complexity with
performance. Two important variants, corresponding to slow- and
fast-hopping, are also addressed with the latter offering symbol
recovery guarantees. Performance analysis and simulation results
illustrate the merits of GFH-OFDMA relative to conventional OFDMA and
long code DS-CDMA with pseudorandom noise codes and RAKE reception
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