The Indoor Propagation Channel

Conclusions

In this chapter, we have investigated the characteristics of the in-door propagation channel, since it represents a key boundary condition of our WLAN application. Its main characteristic is that it features strong multipath propagation at both ends of the communication link. Multipath propagation leads to frequency and spatial selectivity, that are commonly quantified in terms of the coherence bandwidth Δf_c and coherence distance Δp_crespectively.

Since this book concerns the use of antenna array processing, we are particularly interested in the spatial characteristics of the propagation channel. In this context, we discussed two-dimensional ray-tracing, which allows to generate spatio-temporal channel responses of representative WLAN environments. Not only do they provide us with typical values for the aforementioned multipath parameters (,Δf _c ≈ 10MHz and Δp _c ≈λ/4), but also, they are used in all our performance simulations, hence precluding unrealistic assumptions concerning the spatial correlation among the antenna elements (≈0.23, for an inter-element distance of λ/2).

Finally, we have described the statistical Rayleigh model, which is widely used to model the channel in analytical derivations. It was demonstrated that it is a somewhat optimistic approximation of the ray tracing channel responses.