SUMMARYThis paper presents a simple, quasi-static, non-linear (saturated mode) NMOS drain-current model for Volterra-series analysis. The model is based on a linear transconductance, a linear drain-source conductance and a purely non-linear drain-source current generator. The drain-current dependency on both drain-source and gate-source voltages is included. Model parameters are then extracted from direct numerical di erentiation of DC I=V measurements performed on a 160 脳 0:25 m NMOS device. This paper presents the Volterra analysis of this model, including algebraic expressions for intercept points and output spectrum. The model has been veri每ed by comparing measured two-tone iIP 2 and iIP 3 with the corresponding model predictions over a wide range of bias points. The correspondence between the modelled and measured response is good.
This article proposes a novel way of grouping users in an orthogonal frequency division multiplexing (OFDM) communication link based on predefined criteria. The total available spectrum is divided into a number of bands equal to the number of groups. For efficient time-frequency resource allocation, sub-carrier and band hopping are used simultaneously. Under some constraints, sub-carriers can also be assigned to different users based on known channel characteristics using dynamic sub-carrier allocation. Sub-carrier and band hopping are used for mitigating the frequency selectivity of the wireless channel and for minimizing and avoiding interference in the system. The proposed scheme is equally applicable to both downlink and uplink.
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