Home eNB

It is possible to use an additional element set, which is called Home eNB and 
Home eNB Gateway. Specific aspects for the Home eNB, that is, HeNB, are the following:


. HeNB are equipment that can be utilized in the customer’s premises and that uses the licensed operator’s spectrum;
. HeNB is meant for the enhancing of the network coverage and/or capacity;
. includes all the eNB functionalities, added by the HeNB-specific functions that are related to the configuration and security.

The Home eNB Gateway (HeNB GW), which is related to the HeNB, solves the problem of support for a possibly very large number of S1 interfaces. It is thus an additional element that can be used for the balancing of the interfaces.

Furthermore, the HeNB concept can be utilized in the following access scenarios:
. in the closed access mode, only predefined Closed Subscriber Group (CSG) members can access the respective HeNB;
. in the hybrid access mode, both the members and nonmembers of the closed subscriber group can access the HeNB, but the members are prioritized over the nonmembers,

 for example,
if there is congestion;
. in the open access mode, HeNB is seen by the members and nonmembers exactly as a normal eNB.
The correct functioning of the closed and hybrid modes requires additional parameters in order to support the identification and search of the HeNB by UE. The mobility management should also be aware of the HeNBs in order to perform the handovers.



Release 9 of LTE includes enhancements for the HeNB concept. Some of the most important radio access additions are [5]:

. Inbound Mobility;
. Access Control;
. new Hybrid Cell concept;
. management of out-of-date CSG info;
. Operation, Administration and Maintenance for HeNB elements;
. operator controlled CSG list;
. RF Requirements for TDD and FDD HeNBs.


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