This research presents development of a novel algorithm for a continuous wave 24GHz Doppler radar DSP module, intended to estimate land-based vehicle traffic parameters - velocity, lane, shape. Proposed signal processing algorithm uses well known zero crossing method, filtering, least mean square method and scattering center models to estimate counted parameters. Our previous publications [1], [2], [3] describe this algorithm in details and design FPGA chip. As it is shown in [3] FPGA chip complexity and accuracy of result is directly proportional to number of scattering center. Because of here we concentrate on simplified scattering center models, and estimate possible parameters extraction for simplified models to reduce complexity, but don't lose the accuracy. For prototyping the algorithm, the Matlab/Simulink software has been used. In this research it is shown that radical limiting of number of scattering centers can be useful for simplified detection of the shape and velocity of vehicle.