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ABSTRACT: The authors construct a new family of 2<sup>n</sup> codes, called
2<sup>n</sup> extended prime codes, for all-optical code-division
multiple access (AOCDMA) applications. Such 2<sup>n</sup> codes are
obtained by “extending” prime codes. As a result, the
cross-correlation constraint of the new codes is equal to one, as
opposed to two in the original prime codes or 2<sup>n</sup> prime codes.
Moreover the bit error rate (BER) of AOCDMA systems using the new codes
is analysed. It is shown that the new codes can support a larger number
of active users than the 2<sup>n</sup> prime codes for a given BER
IEE Proceedings - Communications 11/1998; · 0.32 Impact Factor
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J.-G. Zhang
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ABSTRACT: In code-division multiple-access (CDMA) systems using all-optical
signal processing, the optical multiple-access interference (OMAI)
degrades the system performance and can ultimately limit the number of
active users. To reduce the effect of OMAI, error-correction codes are
used in both asynchronous and synchronous fibre-optic CDMA systems. It
is shown that the use of asymmetric error-correction binary block codes
can not only effectively reduce the bit-error rate, but also increase
the maximum number of active users in a constant-bandwidth network more
efficiently than using symmetric error-correction binary block codes.
Therefore, this permits implementation of a cost-effective fibre-optic
CDMA network
IEE Proceedings - Communications 11/1997; · 0.32 Impact Factor
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ABSTRACT: A new family of 2(n) codes, called 2(n) extended-prime codes, is proposed for all-optical code-division multiple-access networks. Such 2(n) codes are derived from so-called extended-prime codes so that their cross-correlation functions are not greater than 1, as opposed to 2 for recently proposed 2(n) prime codes. As a result, a larger number of active users can now be supported by the new codes for a given bit-error rate than can be by 2(n) prime codes, while power-efficient, waveguide-integrable all-serial coding and correlating configurations proposed for the 2(n) prime codes can still be employed.
Applied Optics 10/1997; 36(26):6664-7. · 1.41 Impact Factor
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ABSTRACT: In optical code-division multiple access (OCDMA) networks using a
well-known prime code, the code weight w is always fixed to the maximum
number of users M (i.e. the code size). When M becomes very large the
resulting cost and optical power losses of OCDMA encoder/decoder can be
very high. To overcome this difficulty, an efficient design is presented
for OCDMA networks, which is based on the modified prime (MPR) codes.
The use of MPR codes can maintain the fixed w for a given bit error rate
and any M. While MPR codes still preserve the same cross-correlation
constraint as prime codes
Electronics Letters 03/1997; · 0.96 Impact Factor
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J.-G. Zhang
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ABSTRACT: The authors present new address codes for all-optical code
division multiple access (CDMA) systems. The use of the proposed code
can strictly guarantee the peaks of all the cross-correlation functions
and all the sidelobes of any auto-correlation function to be `l' in such
applications as purely asynchronous data transmission and ultrafast
switching. The theory of the new codes is also reported
Electronics Letters 07/1996; · 0.96 Impact Factor
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ABSTRACT: A special class of 2<sup>n</sup> code, derived from the well-known
prime-sequence code, for optical code-division multiple-access (CDMA) is
constructed. A hybrid coding architecture, comprising a `modified'
tunable prime encoder and 2<sup>n</sup> decoder, is proposed and
particularly suitable for waveguide implementation for the future
optical CDMA networks, with potentially 3 dB ideal power loss
Electronics Letters 04/1994; · 0.96 Impact Factor
