# US 2014/0153545 A1 · Handover in a soft cell network

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- Number: US 2014/0153545 A1
- Document ID: US20140153545A1
- Status: Published application
- Kind: A1
- Application number: 13/705,007
- Filed: 2012-12-04
- Published: 2014-06-05
- Earliest claimed: 2012-12-04
- Assignees: Telefonaktiebolaget L M Ericsson (publ)
- Applicants: Telefonaktiebolaget L M Ericsson (Publ)
- Inventors: Konstantinos DIMOU; Stefano Sorrentino
- Web page: https://patentgrep.com/patent/US20140153545A1

## CPC

- H04W 36/302: {due to low signal strength}
- H04W 36/04: Reselecting a cell layer in multi-layered cells
- H04W 84/045: {using private Base Stations, e.g. femto Base Stations, home Node B}
- H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72)

## Abstract

Devices and methods for making a determination whether or not to handover a user equipment (UE) from a serving cell to a target cell are disclosed. The decision is based on a comparison that includes both control plane and data plane link quality considerations. The disclosed devices and methods may be applied to handover determinations in heterogeneous networks that implement a soft cell configuration.

## Claims

### Claim 1

A method for improving the quality of service in a communication network having a serving cell and a target cell, comprising:
receiving at a first network node:
a serving cell control plane value indicating a control plane link quality between a user equipment (UE) and the serving cell,
a serving cell data plane value indicating a data plane link quality between the UE and the serving cell,
a target cell control plane value indicating a control plane link quality between the UE and a target cell detected by the UE, and
a target cell data plane value indicating a data plane link quality between the UE and the target cell;
comparing said serving cell control plane value and said serving cell data plane value to said target cell control plane value and said target cell data plane value; and
initiating a handoff of said UE based on said comparison,
wherein said target cell control plane value and said target cell data plane value are based at least in part on transmissions from one or more target network nodes in said target cell.

### Claim 2 (depends on 1)

The method of claim 1, wherein said serving cell control plane value and said target cell control plane value are based on one or more reference signal received power (RSRP) measurements by said UE.

### Claim 3 (depends on 1)

The method of claim 1, wherein at least one of said serving cell data plane value and said target cell data plane value are based on at least one of measurements of a channel state information reference signal (CSI-RS), reference signal received power (RSRP) measurements, received signal reference quality (RSRQ) measurements, and channel quality indicator (CQI) estimates for feedback.

### Claim 4 (depends on 1)

The method of claim 1, wherein at least one of said serving cell data plane value and said target cell data plane value are based on measurements of a synchronization signal.

### Claim 5 (depends on 1)

The method of claim 1, wherein said serving cell control plane value, said serving cell data plane value, said target cell control plane value, and said target cell data plane value are received from said UE.

### Claim 6 (depends on 1)

The method of claim 1, wherein said handoff is initiated if said comparing step indicates that:
α·ControlPlaneValueTarget+β·DataPlaneValueTarget>α·ControlPlaneValueServing+β·DataPlaneValueServing+γ·X+δ·Y,
where α, β, γ, and δ are handover weighting factors, ControlPlaneValueTarget is said target cell control plane value, ControlPlaneValueServing is said serving cell control plane value, DataPlaneValueTarget is said target cell data plane value, DataPlaneValueServing is said serving cell data plane value, and X and Y are handover values.

### Claim 7 (depends on 6)

The method of claim 6, wherein said handover value X is a handover hysteresis value and said handover value Y is a cell specific offset value.

### Claim 8 (depends on 6)

The method of claim 6, wherein said handover weighting factor a is greater than or equal to said handover weighting factor β.

### Claim 9 (depends on 6)

The method of claim 6, wherein said handover weighting factor a is less than said handover weighting factor β.

### Claim 10 (depends on 6)

The method of claim 6, wherein said handover weighting factors range from 0 to 1.

### Claim 11 (depends on 1)

The method of claim 1, wherein said serving cell is a soft cell and includes a second network node, and
said serving cell data plane value is based on a data signal transmitted by said second network node.

### Claim 12 (depends on 1)

The method of claim 1 wherein said one or more target network nodes includes a first target network node and a second target network node,
said target cell control plane value is based on a signal transmitted by said first target network node, and
said target cell data plane value is based on a data signal transmitted by said second target network node.

### Claim 13 (depends on 2)

The method of claim 2, further comprising:
determining whether said serving cell control plane value exceeds an RSRP threshold level, and
wherein said initiating step is based at least in part on said determination that said serving cell control plane value exceeds said RSRP threshold level.

### Claim 14 (depends on 13)

The method of claim 13, wherein said first network node initiates a handoff of said UE if said serving cell control plane value is less than said RSRP threshold level.

### Claim 15

A method for improving the quality of service in a communication network having a serving cell and a target cell, comprising:
receiving at a first network node:
a serving cell control plane downlink value indicating a downlink control plane link quality between a user equipment (UE) and the serving cell,
a serving cell data plane uplink value indicating an uplink data plane link quality between the UE and the serving cell,
a target cell control plane downlink value indicating a downlink control plane link quality between the UE and a target cell detected by the UE, and
a target cell data plane uplink value indicating an uplink data plane link quality between the UE and the target cell;
determining at said first network node a serving cell data plane uplink value indicating an uplink data plane link quality between the UE and the serving cell,
comparing said serving cell control plane downlink value and said serving cell data plane uplink value to said target cell control plane downlink value and said target cell data plane uplink value; and
initiating a handoff of said UE based on said comparison,
wherein said serving cell data plane uplink value is received from a second network node in said serving cell, said target cell data plane uplink value is received from one or more target network nodes in said target cell, and said target cell control plane downlink value is based at least in part on transmissions from said one or more target network nodes in said target cell.

### Claim 16 (depends on 15)

The method of claim 15, wherein said serving cell data plane uplink value is determined based on a received uplink sounding reference signal (SRS) or uplink signal to interference to noise ratio (SINR).

### Claim 17 (depends on 15)

The method of claim 15, wherein said serving cell control plane downlink value and said target cell control plane downlink value are based on one or more reference signal received power (RSRP) measurements by said UE.

### Claim 18 (depends on 15)

The method of claim 15, wherein said handoff is initiated if said comparing step indicates that:
α·ControlPlaneValueTarget+β·DataPlaneValueTarget>α·ControlPlaneValueServing+β·DataPlaneValueServing+γ·X+δ·Y,
where α, β, γ, and δ are handover weighting factors, ControlPlaneValueTarget is said target cell control plane downlink value, ControlPlaneValueServing is said serving cell control plane downlink value, DataPlaneValueTarget is said target cell data plane uplink value, DataPlaneValuesServing is said serving cell data plane uplink value, and X and Y are handover values.

### Claim 19 (depends on 18)

The method of claim 18, wherein said handover value X is a handover hysteresis value and said handover value Y is a cell specific offset value.

### Claim 20 (depends on 18)

The method of claim 18, wherein said handover weighting factor a is greater than or equal to said handover weighting factor β.

### Claim 21 (depends on 18)

The method of claim 18, wherein said handover weighting factor a is less than said handover weighting factor β.

### Claim 22 (depends on 18)

The method of claim 18, wherein said handover weighting factors range from 0 to 1.

### Claim 23

A network node operable in a communication network having a serving cell and a target cell, comprising:
a receiver configured to receive:
a serving cell control plane value indicating a control plane link quality between a user equipment (UE) and the serving cell,
a serving cell data plane value indicating a data plane link quality between the UE and the serving cell,
a target cell control plane value indicating a control plane link quality between the UE and a target cell detected by the UE, and
a target cell data plane value indicating a data plane link quality between the UE and the target cell; and
a processor configured to:
compare said serving cell control plane value and said serving cell data plane value to said target cell control plane value and said target cell data plane value; and
initiate a handoff of said UE based on said comparison,
wherein said target cell control plane value and said target cell data plane value are based at least in part on transmissions from one or more target network nodes in said target cell and said network node is located within said serving cell.

### Claim 24 (depends on 23)

The network node of claim 23, wherein said serving cell control plane value and said target cell control plane value are based on one or more reference signal received power (RSRP) measurements by said UE.

### Claim 25 (depends on 23)

The network node of claim 23, wherein at least one of said serving cell data plane value and said target cell data plane value are based on at least on of measurements of a channel state information reference signal (CSI-RS), reference signal received power (RSRP) measurements, received signal reference quality (RSRQ) measurements, and channel quality indicator (CQI) estimates for feedback.

### Claim 26 (depends on 23)

The network node of claim 23, wherein at least one of said serving cell data plane value and said target cell data plane value are based on measurements of a synchronization signal.

### Claim 27 (depends on 23)

The network node of claim 23, wherein said serving cell control plane value, said serving cell data plane value, said target cell control plane value, and said target cell data plane value are received from said UE.

### Claim 28 (depends on 23)

The network node of claim 23, wherein said processor is configured to initiate a handoff if:
α·ControlPlaneValueTarget+β·DataPlaneValueTarget>α·ControlPlaneValueServing+β·DataPlaneValueServing+γ·X+δ·Y,
where α, β, γ, and δ are handover weighting factors, Control/PlaneValueTarget is said target cell control plane value, ControlPlaneValueServing is said serving cell control plane value, DataPlaneValueTarget is said target cell data plane value, DataPlaneValueServing is said serving cell data plane value, and X and Y are handover values.

### Claim 29 (depends on 28)

The network node of claim 28, wherein said handover value X is a handover hysteresis value and said handover value Y is a cell specific offset value.

### Claim 30 (depends on 28)

The network node of claim 28, wherein said handover weighting factor a is greater than or equal to said handover weighting factor β.

### Claim 31 (depends on 28)

The network node of claim 28, wherein said handover weighting factor a is less than said handover weighting factor β.

### Claim 32 (depends on 28)

The network node of claim 28, wherein said handover weighting factors range from 0 to 1.

### Claim 33 (depends on 23)

The network node of claim 23, wherein said serving cell is a soft cell and includes a second network node, and
said serving cell data plane value is based on a data signal transmitted by said second network node.

### Claim 34 (depends on 23)

The network node of claim 23, wherein said one or more target network nodes includes a first target network node and a second target network node,
said target cell control plane value is based on a signal transmitted by said first target network node, and
said target cell data plane value is based on a data signal transmitted by said second target network node.

### Claim 35 (depends on 24)

The network node of claim 24, wherein said processor is further configured to:
determine whether said serving cell control plane value exceeds an RSRP threshold level, and
initiate a handoff of said UE if said serving cell control plane value is less than said RSRP threshold level.

### Claim 36

A network node operable in a communication network having a serving cell and a target cell, comprising:
a receiver configured to receive:
a serving cell control plane downlink value indicating a downlink control plane link quality between a user equipment (UE) and the serving cell,
a serving cell data plane uplink value indicating an uplink data plane link quality between the UE and the serving cell,
a target cell control plane downlink value indicating a downlink control plane link quality between the UE and a target cell detected by the UE, and
a target cell data plane uplink value indicating an uplink data plane link quality between the UE and the target cell;
a processor configured to:
compare said serving cell control plane downlink value and said serving cell data plane uplink value to said target cell control plane downlink value and said target cell data plane uplink value; and
initiate a handoff of said UE based on said comparison,
wherein said network node is located in said serving cell, said serving cell data plane uplink value is received from a second network node in said serving cell, said target cell data plane uplink value is received from one or more target network nodes in said target cell, and said target cell control plane downlink value is based at least in part on transmissions from said one or more target network nodes in said target cell.

### Claim 37 (depends on 36)

The network node of claim 36, wherein said target cell data plane uplink value and said serving cell data plane uplink value are uplink sounding reference signal (SRS) values or uplink signal to interference to noise ratios (SINR).

### Claim 38 (depends on 36)

The network node of claim 36, wherein said serving cell control plane downlink value and said target cell control plane downlink value are based on one or more reference signal received power (RSRP) measurements by said UE.

### Claim 39 (depends on 36)

The network node of claim 36, wherein said processor is configured to initiate a handoff if:
α·ControlPlaneValueTarget+β·DataPlaneValueTarget>α·ControlPlaneValueServing+β·DataPlaneValueServing+γ·X+δ·Y,
where α, β, γ, and δ are handover weighting factors, ControlPlaneValueTarget is said target cell control plane downlink value, ControlPlaneValueServing is said serving cell control plane downlink value, DataPlaneValueTarget is said target cell data plane uplink value, DataPlaneValueServing is said serving cell data plane uplink value, and X and Y are handover values.

### Claim 40 (depends on 39)

The network node of claim 39, wherein said handover value X is a handover hysteresis value and said handover value Y is a cell specific offset value.

### Claim 41 (depends on 39)

The network node of claim 39, wherein said handover weighting factor α is greater than or equal to said handover weighting factor β.

### Claim 42 (depends on 39)

The network node of claim 39, wherein said handover weighting factor α is less than said handover weighting factor β.

### Claim 43 (depends on 39)

The network node of claim 39, wherein said handover weighting factors range from 0 to 1.