Receivers with chip-level decision feedback equalizer for CDMA downlink channels

  • Authors:
  • Jinho Choi;Seong Rag Kim;Cheng-Chew Lim

  • Affiliations:
  • Sch. of Electr. Eng. & Telecommun., Univ. of New South Wales, NSW, Australia;-;-

  • Venue:
  • IEEE Transactions on Wireless Communications
  • Year:
  • 2004

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Abstract

For the code division multiple access (CDMA) downlink channel, we investigate the decision feedback equalizer (DFE) at chip-level to effectively suppress multiple-access interference (MAI) when the spreading sequences are orthogonal. The structure of the receiver with the chip-level DFE has been investigated and the minimum mean-square error solution has been derived. Due to the inherent structure of the chip-level DFE, some iterative techniques with hard and soft decisions have been proposed. It is shown that the proposed receivers with the chip-level DFE can provide satisfactory performance. In comparison with the adaptive chip-level linear equalizer, the number of users can be doubled by using adaptive chip-level DFE at a bit-error rate of 10-3. Throughout the paper, we assume that scrambled orthogonal codes are used for spreading sequences.