Load sharing in a cellular radio communication system

1. A method for facilitating load sharing between a serving cell and a neighboring cell of a cellular radio communication system, the serving cell serving a plurality of radio devices, the method comprising a network node of the cellular radio communication system:

defining a first group of radio devices, wherein the first group is a subgroup of the plurality of radio devices served by the serving cell;

associating the first group of radio devices with a load sharing boundary to a load sharing zone between the serving cell and the neighboring cell, beyond which load sharing boundary any of the radio devices in the first group is regarded as being able to be handed over to the neighboring cell;

gathering statistics relating to connection failures experienced by the radio devices in the first group; and

adjusting the load sharing boundary based on the gathered statistics, wherein the adjusting is group-specific so as to account for characteristics of the radio devices within the first group independently of characteristics of radio devices in any other groups of the plurality of radio devices, wherein the load sharing zone supported by the radio devices of the first group is configurable to be of a different size than a load sharing zone supported by another group of radio devices of the plurality of radio devices.

2. The method of claim 1 , wherein the adjusting the load sharing boundary comprises adjusting the load sharing boundary in view of an allowed connection failure ratio.

3. The method of claim 1 , wherein the defining the first group comprises dividing the plurality of radio devices served by the serving cell into at least a first group and a second group.

4. The method of claim 3 , wherein the dividing the plurality of radio devices comprises dividing the radio devices into the groups based on any of: connection status, mobility pattern, quality of service configuration for active bearers, service or application used, and capabilities of the plurality of radio devices.

5. The method of claim 1 , wherein the gathering statistics comprises receiving information about at least one of the following experienced by the radio devices in the first group:

signal quality;

type of connection failure;

cause of connection failure;

number of connection failures during a predetermined time period;

number of connection failures per radio device in the first group; and

number of connection failures per radio device when positioned in the load sharing zone.

6. The method of claim 1 , wherein the network node is comprised in either a serving radio access network (RAN) node providing the serving cell or a radio network controller (RNC), or a base station controller (BSC), or an operations, administration and management (OAM) node.

7. The method of claim 1 , further comprising performing a handover, from the serving cell to the neighboring cell, of a radio device comprised in the first group when the radio device is beyond the load sharing boundary.

8. The method of claim 1 , wherein the method further comprises:

determining that a radio device of the first group has passed the load sharing boundary; determining that load sharing is desired;

deciding to hand over the radio device to the neighboring cell; and

performing a handover from the serving cell to the neighboring cell.

9. The method of claim 1 , wherein the network node is a network node of a core network.

10. The method of claim 1 ,

wherein the method further comprises defining a second group of radio devices that is a subgroup of the plurality of radio devices, wherein the second group is comprised of radio devices with different capabilities than radio devices of the first group, and the second group is associated with a second load sharing boundary to a second load sharing zone overlapping with the first load sharing zone, beyond which second load sharing boundary any of the radio devices in the second group is regarded as being able to be handed over to the neighboring cell; and

wherein the adjusted load sharing boundary is different than the second load sharing boundary.

11. A computer program product stored in a non-transitory computer readable medium for facilitating load sharing between a serving cell and a neighboring cell of a cellular radio communication system, the serving cell serving a plurality of radio devices, the computer program product comprising software instructions which, when run on processing circuitry of a network node of the cellular radio communication system, causes the network node to:

define a first group of radio devices, wherein the first group is a subgroup of the plurality of radio devices served by the serving cell;

associate the first group of radio devices with a load sharing boundary to a load sharing zone between the serving cell and the neighboring cell, beyond which load sharing boundary any of the radio devices in the first group is regarded as being able to be handed over to the neighboring cell;

gather statistics relating to connection failures experienced by the radio devices in the first group; and

adjust the load sharing boundary based on the gathered statistics in a group-specific manner so as to account for characteristics of the radio devices within the first group independently of characteristics of radio devices in any other groups of the plurality of radio devices, wherein the load sharing zone supported by the radio devices of the first group is configurable to be of a different size than a load sharing zone supported by another group of radio devices of the plurality of radio devices.

12. A network node in a cellular radio communication system, configured for facilitating load sharing between a serving cell and a neighboring cell of the cellular radio communication system, the serving cell serving a plurality of radio devices, the network node comprising:

processing circuitry; and

memory storing instructions that, when executed by the processing circuitry, cause the network node to:

define a first group of radio devices, wherein the first group is a subgroup of the plurality of radio devices served by the serving cell;

associate the first group of radio devices with a load sharing boundary to a load sharing zone between the serving cell and the neighboring cell, beyond which load sharing boundary any of the radio devices in the first group is regarded as being able to be handed over to the neighboring cell;

gather statistics relating to connection failures experienced by the radio devices in the first group; and

adjust the load sharing boundary based on the gathered statistics in a group-specific manner so as to account for characteristics of the radio devices within the first group independently of characteristics of radio devices in any other groups of the plurality of radio devices, wherein the load sharing zone supported by the radio devices of the first group is configurable to be of a different size than a load sharing zone supported by another group of radio devices of the plurality of radio devices.

13. The network node of claim 12 , wherein the memory stores instructions that, when executed by the processing circuitry, cause the network node to:

determine that a radio device of the first group has passed the load sharing boundary;

determine that load sharing is desired;

decide to hand over the radio device to the neighboring cell; and

perform a handover from the serving cell to the neighboring cell.

14. The network node of claim 12 , wherein the network node is a network node of a core network.

15. The network node of claim 12 , wherein the memory stores instructions that, when executed by the processing circuitry, cause the network node to:

define a second group of radio devices that is a subgroup of the plurality of radio devices, wherein the second group is comprised of radio devices with different capabilities than radio devices of the first group, and the second group is associated with a second load sharing boundary to a second load sharing zone overlapping with the first load sharing zone, beyond which second load sharing boundary any of the radio devices in the second group is regarded as being able to be handed over to the neighboring cell;

wherein the adjusted load sharing boundary is different than the second load sharing boundary.