Novel Low-Density Signature for Synchronous CDMA Systems Over AWGN Channel

Novel low-density signature (LDS) structure is proposed for transmission and detection of symbol-synchronous communication over memoryless Gaussian channel. Given N as the processing gain, under this new arrangement, users' symbols are spread over N chips but virtually only d v < N chips tha...

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Vydáno v:	IEEE transactions on signal processing Ročník 56; číslo 4; s. 1616 - 1626
Hlavní autoři:	Hoshyar, R., Wathan, F.P., Tafazolli, R.
Médium:	Journal Article
Jazyk:	angličtina
Vydáno:	New York, NY IEEE 01.04.2008 Institute of Electrical and Electronics Engineers The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Témata:	Applied sciences AWGN channels Beta Channels Chip-level iterative SISO MUD Chips Code Division Multiple Access Code division multiplexing Coding, codes Detection, estimation, filtering, equalization, prediction Exact sciences and technology Forward error correction Gaussian channel Gaussian channels Information, signal and communications theory Intersymbol interference Iterative algorithms low-density signature Message passing message passing algorithm Multiaccess communication Multiple access interference Multiuser detection Optimization overloaded condition Signal and communications theory Signal, noise Signatures Spread spectrum Spreads Symbols Telecommunications and information theory Multiuser detection Performance evaluation Multiple access overloaded condition Gaussian channel Wireless telecommunication Iterative method message passing algorithm Decoding Optimal detection Algorithm AWGN channels Memoryless channel Message passing Simulation Overload Synchronous transmission Code division multiple access Chip-level iterative SISO MUD Robustness low-density signature Signal detection
ISSN:	1053-587X, 1941-0476
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Popis
Shrnutí:	Novel low-density signature (LDS) structure is proposed for transmission and detection of symbol-synchronous communication over memoryless Gaussian channel. Given N as the processing gain, under this new arrangement, users' symbols are spread over N chips but virtually only d v < N chips that contain nonzero-values. The spread symbol is then so uniquely interleaved as the sampled, at chip rate, received signal contains the contribution from only d c < K number of users, where K denotes the total number of users in the system. Furthermore, a near-optimum chip-level iterative soft-in-soft-out (SISO) multiuser decoding (MUD), which is based on message passing algorithm (MPA) technique, is proposed to approximate optimum detection by efficiently exploiting the LDS structure. Given beta = K/N as the system loading, our simulation suggested that the proposed system alongside the proposed detection technique, in AWGN channel, can achieve an overall performance that is close to single-user performance, even when the system has 200% loading, i.e., when beta = 2. Its robustness against near-far effect and its performance behavior that is very similar to optimum detection are demonstrated in this paper. In addition, the complexity required for detection is now exponential to dc instead of K as in conventional code division multiple access (CDMA) structure employing optimum multiuser detector.
Bibliografie:	ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 14 ObjectType-Article-2 ObjectType-Feature-1 content type line 23
ISSN:	1053-587X 1941-0476
DOI:	10.1109/TSP.2007.909320