Optimisation of Home eNodeBs ~ Management of Relays and Repeaters - - PowerPoint PPT Presentation

FP7 ICT-SOCRATES

Optimisation of Home eNodeBs ~ Management of Relays and Repeaters

Ove Linnell Ericsson Research 2009-09-30

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Optimisation of Home eNodeBs – Introduction

• Extensive use of indoor solutions, e.g. HeNBs, foreseen

Up to 70% of the traffic load is indoor

• Used to improve or create coverage and/or capacity in small areas
• Support open and closed subscriber groups
• Minimal human intervention
• Self-optimisation needed
• Two use cases are studied:

– Home eNodeB Handover Optimisation – Decide if handover should take place – Optimise handover parameters – Home eNodeB Interference and Coverage Optimisation – Optimise the coverage area while minimising interference

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Optimisation of Home eNodeBs – Control Parameters and Operator Policy

Prioritized Control parameters

• For handover optimization

– Hysteresis – Cell Offset

Operators may have different marketing priorities and performance targets that should be reflected in the self-optimisation. Attributes proposed for prioritisation:

• Accessibility (e.g. call setup success ratio)
• Retainability (e.g. call dropping ratio)
• Quality (e.g. user throughput)
• Coverage
• Other possible requirements

– Limit on change in macro performance – Ability to over-ride the self-optimisation

Utility function proposed

• For interference and coverage optimization

– Maximum HeNB power – Reference signal power – Maximum UE power – Desired received power in HeNB (P0)

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Optimisation of Home eNodeBs – Assessment Criteria

• Need for metrics and methods to assess the gain of self-optimisation

HeNB objectives:

• High throughput for data
• Satisfactory speech quality for voice
• Avoid blocked/dropped calls
• Minimise negative impact of HeNB on macro network
• Overall metric based on comparison between HeNB with self-organisation

and a reference case

Overall metric for assessment of algorithm X (Alg_X) Weighted sum of various blocking and dropping metrics Weighted sum of various QoS metrics Coverage metric Capacity metric Reference value for coverage Reference value for capacity

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Optimisation of Home eNodeBs – Simulations

Prioritized scenarios

• For handover optimization

– Open/Closed Access HeNBs – Varying UE speed – Varying HeNB signal strength relative

to eNB strength

– Varying load – Varying service type – Simplified test scenario:

• For interference and coverage optimization

– Closed Access HeNBs – Varying eNB-HeNB distance – Hexagonal scenario, one area with

houses and HeNBs HeNB UE mobility

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Optimisation of Home eNodeBs – HO Simulations

• Best server is determined based purely
• n received signal strength
• Illustration of coverage of HeNBs

(one color per HeNB)

• Using 3GPP HO model

Macro Femto Another femto Macro Femto Back to macro Back to macro

Serving cell Pilot SINR (dB)

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Optimisation of Home eNodeBs – ICO Simulations

• 7 sites with 21 cells, one area with a grid
• f houses and HeNBs
• HeNB placement

varies within the house

• Requested DL

bitrate 1 Mbps

• Impact of varying HeNB DL power, DL Throughput

Maximum Gain Mbps

Pmax = 80 mW Pmax = 200 mW

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Management of Relays and Repeaters – Introduction I (II)

• Relays and repeaters are used to increase coverage and/or capacity of a

eNodeB

• Repeaters receive and amplify the received signal, including received

interference.

• Relays receive the actual data and then retransmit it

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Management of Relays and Repeaters – Introduction II (II)

• A new relay/repeater needs to be connected to the network and to be

configured

• In some situations, the relay/repeater may disturb the network without

improving coverage/capacity

• The following areas have been identified as suitable for self-organisation;

– Selecting locations for Relays and Repeaters – Automatic generation of configuration parameters – Interference coordination – Self-healing aspects – Load balancing aspects – Handover aspects

• For now, the MRR work in SOCRATES has been put on hold due to lack
• f resources and status in standardization

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Management of Relays and Repeaters – Background and Objectives I

• Intelligently Selecting Locations for Relays and Repeaters

– Avoid time-consuming and costly measurements and/or usage of prediction tools – Automatically identify areas with no coverage or low performance – Generate proposals of repeater and relay positions in order to improve coverage and/or

performance

• Automatic Generation of Configuration Parameters

– For repeaters a strong deviation of parameters from mother eNodeB applies – For relays some parameters are to be set up by default values, others are to be deviated from

settings of mother eNodeB

• Interference coordination

– The introduction of relays and repeaters introduces new interference scenarios, which are

significantly different to conventional macro cell networks.

– Manage interference so that both macro and relaying links provide satisfactory throughput and

latency

• Self-healing

– Detection of outages of relays / repeaters – Compensation of outages using relays / repeaters

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Management of Relays and Repeaters – Background and Objectives II

• Resource Sharing

– Relays and Repeaters provide connection for UEs with at least two hops on radio interface,

resources can be shared in time and frequency domain

– Optimisation of resources used in links to/from repeater with regards to – Throughput – Interference

• Load balancing aspects

– Additional load on backhaul link (eNB – RN) should be considered in load balancing

problems

– Load balancing between eNB direct user links and backhaul links of the RNs

• Handover aspects

– With Relays and Repeaters, handover settings should be adjusted for handover between – Macro to macro – Macro to relay – Relay to macro – Relay to relay