A spectrally modulated, spectrally encoded (SMSE) framework is adopted for implementing code division multiple access (CDMA) with partial band interference suppression. SMSE signals are constructed within an architecture governed by cognitive radio (CR) principles and supported by software defined radio (SDR) implementation, a union referred to as CR- based SDR. Orthogonal frequency division multiplexing (OFDM) signals, a foundational part of future 4G systems, are collectively classified as SMSE because data modulation and encoding are applied in the spectral domain. Framework applicability was demonstrated for realistic 4G signals by illustrating consistency between resultant analytic SMSE expressions and published results. Framework implementability and flexibility is further demonstrated herein using more complex CDMA signal structures. Modeling and simulation results are presented for a form of multi-carrier CDMA using polyphase codes with adaptive spectral notching (interference avoidance). Collectively, the SMSE implementation of this system correlates very well with theoretical predictions for multiple access scenarios.
[Show abstract][Hide abstract] ABSTRACT: If radios could somehow use a portion of the broadcast TV spectrum without causing interference, cellular telephony and other important services would be able to exploit those bands. With more room to operate, cellphone calls would be a lot cheaper, as would mobile Internet access, which would get faster as well. Your handset would be able to pull in audio and visual entertainment from all over the globe, and videophoning would finally be a reality. To manage such feats, cellphone handsets would have to be able to shift their frequency of operation on demand and without packing in lots of extra hardware. Telecommunications engineers have a name for that goal software-defined radio. And the more visionary among them see it as a stepping-stone to an even more distant ideal. Their goal is a wireless device that is smart enough to analyze the radio environment and decide for itself the best spectral band and protocol to reach whatever base station it needs to communicate with, at the lowest level of power consumption. The name for such remarkable systems is "cognitive radios," and some are already emerging from the laboratory to be field-tested by the US military, which has long sponsored research in the area
[Show abstract][Hide abstract] ABSTRACT: A wavelet domain communication system architecture is shown,
capable of providing acceptable communication performance while
`avoiding' spectral regions containing interference. Demonstrated bit
error rate improvement averaged 5.7 and 12.4 dB using orthogonal and
antipodal data modulation, respectively, over a range of interference
energy-to-signal energy (I/E) ratios of 0 to 16 dB
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