Examples of Multipath Fading Channels As discussed, when a signal is transmitted through a multipath fading channel, a channel model, which we assume, gives its received characteristics. For instance, the . such as Rayleigh distribution and Ricean distribution describes the envelope fluctuation for an individual multipath component in the channel, the multipath intensity profile or spaced-frequency correlation function determines the frequency selectivity of the channel, and the Doppler power spectrum or spaced-time correlation function determines the time selectivity of the channel. Figure shows examples of multipath delay profiles to describe frequency selectivity of a channel, which we often use in. | 22 Multicarrier Techniques for 4G Mobile Communications Examples of Multipath Fading Channels As discussed when a signal is transmitted through a multipath fading channel a channel model which we assume gives its received characteristics. For instance the . such as Rayleigh distribution and Ricean distribution describes the envelope fluctuation for an individual multipath component in the channel the multipath intensity profile or spaced-frequency correlation function determines the frequency selectivity of the channel and the Doppler power spectrum or spaced-time correlation function determines the time selectivity of the channel. Figure shows examples of multipath delay profiles to describe frequency selectivity of a channel which we often use in this book for computer simulation. Here we can assume that the fading characteristic of each path is independent because ofWSSUS and we often assume a Rayleigh distribution for each envelope and a uniform distribution for each phase. In Figure a there are a fixed number of paths with equidistant delays and the average received powers of multipaths are exponentially decaying. We often encounter this kind of profile in indoor environments 9 10 and we call it an exponentially decaying profile. On the other hand in Figure b there are also a fixed number of paths with equidistant delays but the average received powers of multipaths are all the same. We often use this kind of profile to test a system performance 6 and we call it an independent and identically distributed . profile. The time variation of a channel is determined by a lot of factors such as the height of transmitter receiver antenna the speed of transmitter receiver Figure Examples of multipath delay profiles a an exponentially decaying multipath delay profile and b an . multipath delay profile. Team-Fly Characteristics of Multipath Fading Channels 23 in motion the shape of the antenna the height of surrounding structures and so
