Content for TS 28.104 Word version: 18.3.0

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7.2.5 MDA assisted mobility management 7.2.5.1 Mobility performance analysis 7.2.5.2 Handover optimization analysis 7.2.5.3 Inter-gNB beam selection optimization
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7.2.5 MDA assisted mobility management p. 31

7.2.5.1 Mobility performance analysis p. 31

7.2.5.1.1 Description p. 31

This MDA capability is for the mobility performance analysis.

The mobility performance related problems may result from too-early/too-late/ping-pong handovers due to inappropriate handover parameters. MDAS can be used to analyse service experience and network performance during handover period in different mobility scenarios. MDAS producer may also be capable to provide the recommendations of optimal handover parameters to MDAS consumer.

In different NSA and SA deployment architecture scenarios, handover mechanisms (e.g. DAPS, CHO or RACH-less handover) will have different impacts on the mobility performance. The analytics report to identify the most optimal handover mechanism may be provided by MDAS producer.

7.2.5.1.3 Requirements p. 32

Table 7.2.5.1.3-1

Requirement label	Description	Related use case(s)
REQ-MRO_MDA-01	MDA capability for mobility performance issue analysis shall include providing the mobility performance in NSA and SA deployment architectures.	Mobility performance issue analysis.
REQ-MRO_MDA-02	MDA capability for mobility performance issue analysis shall include providing the mobility issue analysis including too-early handovers, too-late handovers and ping-pong handovers.	Mobility performance issue analysis.
REQ-MRO_MDA-03	MDA capability for mobility performance issue analysis shall include identifying the most optimal handover mechanism including DAPS, CHO or RACH-less handover.	Mobility performance issue analysis.
REQ-MRO_MDA-04	MDA capability for mobility performance issue analysis shall include providing the area specific mobility performance analysis.	Mobility performance issue analysis.

7.2.5.2 Handover optimization analysis p. 32

7.2.5.2.1 Description p. 32

This MDA capability is for the handover optimization analysis.

7.2.5.2.2 Use cases p. 32

7.2.5.2.2.1 Handover optimization p. 32

Current handover procedures are mainly based on radio conditions for selecting the target gNB upon a handover. The target gNB accepts or rejects the Handover (HO) request depending on various conditions. In virtualized environment, the HO may be rejected due to inadequate available resources within the target gNB. The notion of resources may include virtual resources (e.g. compute, memory) and/or radio resources (e.g. PRB, RRC connected users). If the HO request is rejected, a UE will try to connect to a different gNB until the request is successfully accepted. Several target gNBs can be tried until the request is successfully accepted. This process can result in wastage of UE and network resources, while it may also introduce service disruption due to increased latency and Radio Link Failures (RLFs). It also introduces inefficiency in the HO or other network procedures.

To address this handover optimization issue, it is desirable to use MDA (Management Data Analytics) to provision and/or select a particular target gNB for handover in order to reduce or even avoid HO rejections. The MDAS producer provides a HO optimization analytics output containing the current and future/predicted resource consumption, resources capabilities and other KPIs' status for the available target gNB(s). The analytics output also provides recommended actions to optimize the target gNB for handover. This may include resource re-configuration or the updated selection criteria for target gNB. Based on the output, the MDAS consumer adjusts (e.g. scale-out/up the virtual resource, re-schedule/optimize radio resource) the resources before continuing with the handover and/or adjusts the selection criteria of the target gNB by also considering the overlapping coverages of inter-frequency and inter-RAT deployments.

7.2.5.2.2.2 Handover optimization based on UE Load p. 32

The target node, eNB, may not have adequate resources to accept certain handover requests. In the context of network virtualization, these resources may include not only legacy radio resources, but also virtual resources such as processor and memory. Handover optimization can benefit from knowledge about the projected UE load on the target cell including additional radio and virtual resources.

7.2.5.2.3 Requirements p. 33

Table 7.2.5.2.3-1

Requirement label	Description	Related use case(s)
REQ-MOB_MDA-01	MDA capability for handover optimization shall include providing the analytics output related to current statistics and future predictions of virtual resource consumption of gNB.	Handover optimization
REQ-MOB_MDA-02	MDA capability for handover optimization shall include providing the analytics output related to current statistics and future predictions of radio resource consumption of gNB.	Handover optimization.
REQ-MOB_MDA-03	MDA capability for handover optimization shall include providing an analytics output indicating a selection priority for the target cell, among a set of candidate inter-frequency cells.	Handover optimization.
REQ-MOB_MDA-04	MDA capability for handover optimization shall include providing an analytics output indicating a list of target cells to spare, i.e. avoid, a handover for an indicated time period.	Handover optimization.
REQ-MOB_MDA-05	MDA capability for handover optimization shall include providing the analytics output describing inter-frequency target cell selection for handover including information for provisioning or selecting a target gNB with respect to a specific service or slice, if the same Network Slice Instance (NSI) is available in both the current and target gNB.	Handover optimization.
REQ-MOB_MDA-06	MDA capability for handover optimization shall include providing the analytics output describing inter-frequency target cell selection for handover including indication of current and expected QoE (for the UE) at the current and target gNB.	Handover optimization.
REQ-MOB_MDA-07	MDA capability for handover optimization shall include providing the analytics output including the following information that can be used to optimize handover decisions: Indication on whether the target gNB is optimal for handover. Recommended action to optimize the target gNB and/or the selection of the target gNB for handover.	Handover optimization.
REQ-MOB_MDA-08	MDA capability for handover optimization shall include providing an analytics output indicating the projected UE load with respect to virtual resource and radio resource on the target cell.	Handover optimization based on UE Load.

7.2.5.3 Inter-gNB beam selection optimization p. 33

7.2.5.3.1 Description p. 33

This MDA capability is for inter-gNB beam selection optimization.

7.2.5.3.2 Use case p. 33

With the deployment of 5G networks, Massive MIMO has been used on a large scale. Beamforming, as a key technology to reduce user interference, which can suppress interference signals in non-target directions and enhance sound signals in target directions, is always combined with Massive MIMO to further decrease interference. A cell can make use of multiple beams for serving residing users (SSB or CSI-RS) with each user served by a single beam at a time. The cell level quality can be represented as an aggregated metric over one or more beams. So, although handover is performed between two 5G cells, the granularity of handover can be further broken down to beam level.

The handover of beams could be performed if the network resource or the user's state have changed to obtain better network performance. Beam optimization includes the handover between different beams and configuration of beam parameters.

In order to avoid selecting the wrong beam to perform RACH on the target cell and causing RLF of the UE, MDA can be used to recommend a means to prioritize and/or select the beam in case of handover for a specific target cell. MDA can provide a beam level HO optimization analysis considering information on the handover performance of different beam combinations between the source and target cell pairs. Beams of the target cell with a successful handover are preferred in the selection.

MDA could also provide recommended actions and priority options for beam selection. Based on the recommended actions, the MDA MnS consumer adjusts the priorities for the beam selection at HO, i.e. the beam combinations that are likely to succeed are prioritized, less optimal beam combinations are down prioritized. The target cell may also obtain analytics to allocate RACH resources in a way that ensures HO success.

In order to optimize antenna and beam configuration, so as to reduce energy loss and enhance network performance, MDA can be used to analyze the current network status.

7.2.5.3.3 Requirements p. 34

Table 7.2.5.3.3-1

Requirement label	Description	Related use case(s)
REQ-HO_BEAM_OPT-01	MDA capability for inter-gNB beam selection optimization shall include providing the analytics of the handover performance of beam pair combinations between cell pairs.	Inter-gNB beam selection optimization.
REQ-HO_BEAM_OPT-02	MDA capability for inter-gNB beam selection optimization shall include providing an indication if a beam pair is to be prioritized or down prioritized.	Inter-gNB beam selection optimization.
REQ-HO_BEAM_OPT-03	MDA capability for inter-gNB beam selection optimization shall include providing feasible antenna and beam configuration analysis.	Inter-gNB beam selection optimization.