def efficientdet_params(model_name):
    """ Map EfficientDet model name to parameter coefficients. """
    params_dict = {

        'efficientdet-d0': {
            'compound_coef': 0,
            'backbone': 'efficientnet-b0',
            'R_input': 512,
            'W_bifpn': 64,
            'D_bifpn': 3,
            'D_class': 3,
            'params': '3.9M'
        },

        'efficientdet-d1': {
            'compound_coef': 1,
            'backbone': 'efficientnet-b1',
            'R_input': 640,
            'W_bifpn': 88,
            'D_bifpn': 4,
            'D_class': 3,
            'params': '6.6M'
        },

        'efficientdet-d2': {
            'compound_coef': 2,
            'backbone': 'efficientnet-b2',
            'R_input': 768,
            'W_bifpn': 112,
            'D_bifpn': 5,
            'D_class': 3,
            'params': '8.1M'
        },

        'efficientdet-d3': {
            'compound_coef': 3,
            'backbone': 'efficientnet-b3',
            'R_input': 896,
            'W_bifpn': 160,
            'D_bifpn': 6,
            'D_class': 4,
            'params': '12.0M'
        },

        'efficientdet-d4': {
            'compound_coef': 4,
            'backbone': 'efficientnet-b4',
            'R_input': 1024,
            'W_bifpn': 224,
            'D_bifpn': 7,
            'D_class': 4,
            'params': '20.7M'
        },

        'efficientdet-d5': {
            'compound_coef': 5,
            'backbone': 'efficientnet-b5',
            'R_input': 1280,
            'W_bifpn': 288,
            'D_bifpn': 7,
            'D_class': 4,
            'params': '33.7M'
        },

        'efficientdet-d6': {
            'compound_coef': 6,
            'backbone': 'efficientnet-b6',
            'R_input': 1280,
            'W_bifpn': 384,
            'D_bifpn': 8,
            'D_class': 5,
            'params': '51.9M'
        }

    }

    return params_dict[model_name]