Mobile communication systems have evolved over the past decades and each new generation brought new experience to the users enabled by technology innovations, while keeping some well established principles from previous generations. This trend continued up to LTE (Long Term Evolution) Advanced, the predominant 4thgeneration system which has just been standardized in 3GPP and is being rolled out soon. How will this trend continue to future systems which will be deployed in some 10 years from now which will be advanced enough to be called “Beyond 4G” (B4G)? This article presents how such B4G systems will look like and some key technologies they will rely on including versatile numerology, massive virtual MIMO from many base stations, both centralized and distributed architectures using fiber optics as backbone, advanced interference mitigation, cognitive self organization, and wideband RF radios.

The paper discusses block coded multilevel QAM radio systems having nonlinear distortions. The noise induced by the nonlinearity is characterized by histograms calculated from the simulated sampler of the received signal. The overall noise distribution is given both for independent and dependent block symbols. Using this distribution the remaining bit error probability after decoding can be calculated in closed form analysis. The calculation results show that the vulnerability of multilevel QAM radio systems to nonlinear distortions can significantly be reduced by the application of even simple block coded modulation schemes.>

A general error analysis for the noncoherentM-ary orthogonal keyed receiver in the presence of arbitrary Gaussian interference is presented. Relations to well-known formulas which apply to the broadband white Gaussian noise environment are given. Numerical results for various special interference situations are presented, and the impact of unequal values of the noise power in the different receiver channels on the error performance is discussed.