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Summary: 900 IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY, VOL. 50, NO. 4, JULY 2001
Noncoherent MLSE Detection of M-DPSK for
DS-CDMA Wireless Systems
Andrea Abrardo, Member, IEEE
Abstract--This paper focuses on maximum-likelihood sequence
estimation of noncoherent -ary differential phase-shift keying
( -DPSK) receivers for code division multiple-access (CDMA)
systems, which make use of direct-sequence spread-spectrum
modulations. A typical frequency-selective Rayleigh environment
with multipath diversity at the receiver is considered. In this sce-
nario, the optimum noncoherent decision metric, which requires
an estimation of the channel tap weights envelope, is derived. Then,
in order not to increase the receiver implementation complexity, a
joint channel and data estimation strategy is proposed, which does
not require the transmission of a known training sequence (blind
estimation). In this case, the decision metric becomes a simple
equal gain combining of multiple-symbol square-law detection
decision metrics. For this suboptimum noncoherent detector,
useful bounds on the bit error probability are provided through a
theoretical analysis. Nonconstant and constant multipath intensity
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