Connected-mode Mobility in LTE Heterogeneous Networks
In this chapter we consider networks with open subscriber group (OSG) heterogeneous nodes of two types: macro and metro eNBs. It is worth reviewing some definitions that the reader may not be familiar with.
OSG cells can be selected by everyone with a subscription to the mobile operator. This contrasts to closed subscriber group (CSG) cells, such as femtocells, that can be selected by only specific subscribers.
Metros are OSG eNBs with lower maximum transmission power than macros, usually employing antenna configurations that are simpler than those of the macro eNBs but exhibit certain compactness that is usually achieved with increased integration with other space-consuming radio components such as in active antenna arrays.
We consider a mixture of these nodes where the operator macro network is already in place, already achieving some capacity and coverage targets, and metros are deployed as an underlay, usually aiming to fill coverage holes or local throughput improvements. Only simple antenna configurations are considered because the aim in this chapter is to highlight the effect of inter-eNB mobility procedures in connected mode. The connected mode is the mode where the UE has established a connection with its peer radio resource control (RRC) layer at the serving eNB and is actively engaged in user-plane traffic transmission/reception with this ...