Packet access using DS-CDMA with frequency-domain equalization

D. Garg, F. Adachi

Research output: Contribution to journalArticlepeer-review

25 Citations (Scopus)


The next-generation mobile communications system is anticipated to support very high-speed data rates exceeding several tens megabits per second. In this paper, we consider high-speed downlink packet access for direct-sequence code-division multiple access (DS-CDMA) as in third-generation wideband code-division multiple-access systems. Adaptive modulation and coding (AMC), multicode operation and hybrid automatic repeat request (HARQ) will be the enabling technologies. With such high-speed data transmissions, however, multicode operation severely suffers from the loss of orthogonality among the spreading codes since the wireless channel becomes severely frequency-selective. In this paper, we apply frequency-domain equalization (FDE) based on minimum mean-square error (MMSE) criterion instead of conventional rake combining for receiving the packet. A new MMSE-FDE weight is derived for packet combining. The throughput in a frequency-selective Rayleigh-fading channel is evaluated by computer simulation for Chase combining and incremental redundancy (IR) packet combining. It is shown that the use of MMSE-FDE for the reception of multicode DS-CDMA packet gives an improved throughput irrespective of the channel's frequency-selectivity.

Original languageEnglish
Pages (from-to)161-170
Number of pages10
JournalIEEE Journal on Selected Areas in Communications
Issue number1
Publication statusPublished - 2006 Jan


  • Adaptive modulation-coding
  • AMC
  • Data transmission
  • Direct-sequence code-division multiple access
  • HARQ
  • High-speed downlink packet access
  • Hybrid automatic repeat request
  • Multicode operation
  • Next-generation mobile communication
  • Wireless channel


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