At present Cell Broadcast is used for ETWS/CMAS/PWS area warning systems. For the macro network this presents little problem, despite the fact that a warning area may contain a large number of cells in a macro network. Moreover the radio access parameters broadcast over the air in a 3G macro network have traditionally been planned before deployment and change only rarely. The same as above is also applicable for deployments with HNBs, and also in this deployment it is possible to plan that the radio access parameters broadcasted over the air. The use of the Emergency Area ID list concept has a number of benefits to operators that are not currently present in 3G, including:

1. The address list size may be controlled by the use of Emergency Area IDs;
2. The Emergency Area ID allows the grouping of cells other than by TAI.

Increased harmonization between LTE and 3G would also allow an operator to re-use their Emergency Area ID list across RATs, which is particularly beneficial in the case of co-located cell sites or cell supporting multi-RAT operation.

The present document captures the result of the Study on HNB Emergency Warning Area for UTRA (RP-131258 [2]).

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