We introduce and characterize the operational diversity order (ODO) in fading channels, as a proxy to the classical notion of diversity order at any arbitrary operational signal-to-noise ratio (SNR). Thanks to this definition, relevant insights are brought up in a number of cases: (i) We quantify that in line-of-sight scenarios an increased diversity order is attainable compared to that achieved asymptotically; (ii) this effect is attenuated, but still visible, in the presence of an additional dominant specular component; (iii) we confirm that the decay slope in Rayleigh product channels increases very slowly and never fully achieves unitary slope for finite values of SNR.

翻译：我们引入并表征了衰落信道中的操作分集阶数（ODO），并将其作为经典分集阶数概念在任意操作信噪比（SNR）下的近似替代。借助这一定义，我们在若干情形下得出了相关洞见：（i）量化表明，在视距传播场景中可实现比渐近条件下更高的分集阶数；（ii）该效应在存在额外主导镜面分量时会减弱但依然可见；（iii）我们证实，在瑞利乘积信道中，衰落斜率随有限SNR值增加极为缓慢，且永远无法完全达到单位斜率。