Open AccessSpectrally encoded code‐division multiple access for cognitive radio networks
Author(s) -
Najafi Shahla,
Shayesteh Mahrokh G.
Publication year - 2014
Publication title -
iet communications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.355
H-Index - 62
eISSN - 1751-8636
pISSN - 1751-8628
DOI - 10.1049/iet-com.2013.0116
Subject(s) - cognitive radio , underlay , computer science , code division multiple access , computer network , additive white gaussian noise , overlay , fading , spectral efficiency , spread spectrum , telecommunications , electronic engineering , signal to noise ratio (imaging) , wireless , engineering , channel (broadcasting) , programming language
Recent studies have revealed that spectrum congestion is due to the inefficient usage of spectrum against the availability. Cognitive radio is viewed as an approach for improving the utilisation of radio spectrum. The spectrally encoded (spread‐time) code‐division multiple access (SE‐CDMA) technique (which is regarded as the dual of spread spectrum CDMA) is considered and its performance in cognitive radio networks is studied. In cognitive network spectrum, overlay and underlay techniques are employed to enable the primary and secondary users to coexist while improving the overall spectrum efficiency. It is shown that SE‐CDMA provides considerable flexibility to design overlay and underlay waveforms that are scenario‐dependent. The performance of SE‐CDMA method is evaluated in additive white Gaussian noise and fading channels in terms of both primary and secondary users. Moreover, its performance is compared with cognitive radio using soft‐decision spectrally modulated spectrally encoded waveforms. The results indicate the efficiency of SE‐CDMA.