Evaluation of coherent homodyne and heterodyne optical CDMA structures

Mohammad Karbassian, Hooshang Ghafouri-Shiraz

Research output: Contribution to journalArticle

3 Citations (Scopus)


This paper evaluates the coherent optical code-division multiple-access (OCDMA) techniques and examines the overall system performance in terms of signal-to-noise ratio (SNR) penalty as a function of simultaneous users accommodated to maintain an appropriate value of the bit-error rate (BER) for homodyne and heterodyne detections. As spreading codes, the proposed structures are utilizing a recently introduced prime code family hereby referred to as double-padded modified prime code (DPMPC). As a coherent modulation, binary phase-shift keying (BPSK) format is deployed. In homodyne detection, two different phase modulations are studied including either an external phase-modulator or injection-locking methods. The phase limitation and the performance for two methods plus multiple-access interferences (MAI) and receiver noise in a shot-noise limited regime are investigated. In heterodyne detection, BER analysis of the system based on only external phase modulator is examined. It is found that by maintaining BER = 10(-9), this system can accommodate an increased number of simultaneous users to compare with systems which employ conventional bipolar codes.
Original languageEnglish
Pages (from-to)513-524
Number of pages12
JournalOptical and Quantum Electronics
Issue number7
Publication statusPublished - 1 Jan 2008


  • limited phase excursion
  • injection-locking
  • coherent OCDMA
  • prime code family
  • multiple access interference


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