American Journal of Networks and Communications

Volume 3, Issue 4, August 2014

  • Optimal Power Allocation and Power Constraint in OFDM-Based Cognitive Radio Systems

    Nguyen Van Vinh, Pham Ngoc Thang

    Issue: Volume 3, Issue 4, August 2014
    Pages: 49-55
    Received: 29 July 2014
    Accepted: 15 August 2014
    Published: 30 September 2014
    Abstract: Cognitive Radio (CR), which aims to improve spectrum utilization by accessing the spectrum originally licensed to a primary system, is a promising concept. In cognitive radio system based on orthogonal frequency division multiplexing (OFDM), the optimized algorithms for sub-carrier power allocation share the problems of complex iterative calculatio... Show More
  • Signal Shaping to Achieve OOK and PSK Co-Existence for Improved Optical Access Network Performance

    Yasuyuki Okumura, Maki Kato, Katsuyuki Fujii

    Issue: Volume 3, Issue 4, August 2014
    Pages: 56-62
    Received: 28 September 2014
    Accepted: 13 October 2014
    Published: 20 October 2014
    Abstract: This paper proposes a novel symbol mapping that uses signal shaping to alleviate the BER problem in constellation sharing with the use of phase information. This mapping solves one of the most critical problems; the small Euclid distance of the PSK symbols in the constellation sharing of OOK and PSK in Passive Optical Networks (PONs). Constellation... Show More