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 indentifiability 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.
|Original language||English (US)|
|Number of pages||13|
|Journal||IEEE Transactions on Communications|
|State||Published - Apr 2001|
Bibliographical noteFunding Information:
Paper approved by L. Wei, the Editor for CDMA Systems of the IEEE Communications Society. Manuscript received November 1, 1999; revised April 16, 2000 and July 30, 2000. This work was supported by the National Science Foundation Wireless Initiative Grant 99-79443 and the ARL under Grant DAAL01-98-Q-0648. This paper was presented in part at the Wireless Communications and Networking Conference (WCNC), Chicago, IL, September 23–28, 2000.
- Blind channel estimation
- Multicarrier CDMA
- Multipath fading channels
- Spread spectrum systems