NDLI: MAP equalization for DQPSK in multi-pass demodulation

Content Provider	IEEE Xplore Digital Library
Author	Khayrallah, A.S. Fulghum, T. Hui, D.
Copyright Year	2000
Description	Author affiliation: Ericsson, Research Triangle Park, NC, USA (Khayrallah, A.S.)
Abstract	This paper investigates the effect of pilot bits on the performance of a MAP equalizer for DQPSK modulation. This study pertains to IS-136 and the ACELP vocoder error control coding scheme. We present analysis and simulation results that explain the impact of pilot bits in detail. In multi-pass demodulation (MPD), a number of re-encoded bits are available as pilot bits to a 2nd pass demodulator. Previous studies indicate that pilots helps both the channel tracking process and the bit detection process. Here, we assume perfect knowledge of the channel, and we concentrate on the effect of pilots on the decision process. Specifically, we use a MAP equalizer, which is the optimal bit-by-bit decision process. We find that the Class 2 bit error rate (BER) with pilots improves by about 1.5 dB over the baseline with no pilots. This is the case in a non-dispersive channel as well as in a dispersive channel. Since the channel is known, this gain is fully attributable to the decision process. The main application is to improve the performance of IS-136 terminals using MPD.
Starting Page	2249
Ending Page	2256
File Size	477526
Page Count	8
File Format	PDF
ISBN	0780365070
ISSN	10903038
DOI	10.1109/VETECF.2000.883264
Language	English
Publisher	Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Publisher Date	2000-09-24
Access Restriction	Subscribed
Rights Holder	Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Subject Keyword	Demodulation Equalizers Decoding AWGN Vocoders Analytical models Bit error rate Fading Cyclic redundancy check Dispersion
Content Type	Text
Resource Type	Article

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