LTE Release 12: Small Cell Enhancements – Higher Layer Aspects

16 Jul

One of the 3GPP Rel-12 Study Items focuses on Small Cell Enhancements.from the perspective of higher layers. There are 3 scenarios under consideration:

Scenario 1:  Macro and small cells on the same carrier frequency, connected via non-ideal backhaul.

Scenario 2: Macro and small cells on different carrier frequencies, connected via non-ideal backhaul.

Scenario 3: Only small cells on one or more carrier frequencies, connected via non-ideal backhaul.

The challenges posed by these scenarios are summarized in the table below.

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To address these challenges, 3GPP’s RAN Working Group 2, is currently working towards a set of solutions, with the following design goals in mind:

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The idea of ‘dual connectivity’ has more or less been accepted as the way forward. This term refers to operation where a given UE consumes radio resources provided by at least two different network points connected with non-ideal backhaul. Each eNB involved in dual connectivity for a UE may assume different roles and these roles do not necessarily depend on the eNB’s power class and can vary among UEs.

Within the dual-connectivity framework, there are two potential solutions being discussed:

Inter-node radio resource aggregation: This solution is aimed at improving per-user throughput by aggregating radio resources in more than one eNB for user plane data transmission.ImageRRC Diversity: This solution is targeted at improving mobility robustness by transmitting handover related RRC signalling could from/to a potential target cell. The RRC diversity scheme could also be applied for handovers from the macro to pico cells, between macro or between pico cells.

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Further details of these solutions can be found in TR36.842.

Source: http://allabout4g.wordpress.com/2013/07/14/lte-release-12-small-enhancements-higher-layer-aspects/

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