In this chapter we discuss some of the problems already covered so far in the book in the case when the number of network elements (terminals and access points) becomes extremely large, theoretically infinite. In this case we use Mean Field Theory (MFT) as a tool for the sysytem analysis.
20.1 MFT for Large Heterogeneous Cellular Networks
As already discussed in Chapter 11, intercell interference is a crucial issue in heterogeneous networks where different transmitter–receiver pairs compete for system resources. As indicated throughout the book so far, future wireless networks will be of a heterogeneous type whose base stations (BSs) are of different sizes and coherently coexist. Small BSs are to support higher capacity in small areas, while macro BSs are to support large scale mobility. However, such a promising solution has its own implementation obstacles. One of the most difficult problems facing a successful small cells deployment is intercell interference, which may damage the whole network if it is not carefully controlled.
In a heterogeneous network (HetNet), there are two sources of intercell interference. The first interference source arises when a macro BS coverage area is overlapping with many small BSs’ coverage areas, causing cross layer interference. The second interference source manifests when the small BSs’ coverage areas are themselves partially overlapping with each other causing co-layer interference. In such ...