Method for performing a handover of a mobile device

1. A method for performing a handover of a mobile device from a source cell to a target cell in a cellular wireless telecommunication network, the method comprising:

configuring the mobile device to transmit a first handover trigger signal to the source cell, when a difference between a signal strength of the target cell and a signal strength of the source cell as measured by the mobile device is above a first threshold;

determining traffic load in the source cell;

in response to the cell traffic load in the source cell being above a cell traffic load threshold, in addition to the configuration regarding the first handover signal and the first threshold, configuring the mobile device to transmit a second handover trigger signal to the source cell, in response to a difference between a signal strength of the target cell and a signal strength of the source cell as measured by the mobile device being above a second threshold, wherein the first threshold is larger than the second threshold;

storing information about the mobile device that the handover has been performed from the source cell to the target cell after reception of the second handover trigger signal, in response to the handover being performed from the source cell to the target cell after reception of the second handover trigger signal, thereby recording an indication that the handover from the source cell to the target cell has occurred; and

making a further handover of the mobile device from the target cell back to the source cell less likely based on the recorded indication.

2. The method according to claim 1 , wherein the method further comprises:

determining a mobile device traffic load generated by the mobile device in the source cell;

determining if the mobile device traffic load is higher than a mobile device traffic load threshold; and

performing a handover of the mobile device from the source cell to the target cell, if the mobile device traffic load is higher than the mobile device traffic load threshold, when the second handover trigger signal is received by the source cell.

3. The method according to claim 2 , wherein the mobile device traffic load is determined by a minimum bit rate required by the mobile device.

4. The method according to claim 1 , wherein the second handover trigger signal is indicative of at least one cell being located in the vicinity of the mobile device, the at least one cell comprising the target cell.

5. The method according to claim 1 , wherein a location of the mobile device is determined by the source cell and wherein the second handover trigger signal is transmitted only if the location of the mobile device lies outside of a centre region of the source cell.

6. The method according to claim 1 , wherein the second threshold is increased when the cell traffic load in the source cell decreases, and wherein the second threshold is decreased when the cell traffic load in the source cell increases.

7. The method according to claim 1 , wherein the cell traffic load in the source cell is determined by using weighting factors for scheduling a plurality of mobile devices in the source cell, the plurality of mobile devices comprising the mobile device, wherein the weighting factors for scheduling said mobile devices are dependent on a relation of a required minimum bit rate to a transmission bit rate of the mobile devices or dependent on a ratio of the required minimum bit rate and the transmission bit rate of the mobile devices.

8. The method according to claim 1 , the method comprising further:

determining resources used by the mobile device;

determining if the used resources exceed a resource threshold;

performing a handover of the mobile device from the source cell to the target cell, if the used resources exceed a resource threshold, when the second handover trigger signal is received by the source cell.

9. The method according to claim 1 , wherein the information is generated by the source cell, stored in a base station of the source cell, transmitted from the source cell to the target cell and stored in a base station of the target radio cell.

10. The method according to claim 1 , wherein the information is stored in the mobile device, and wherein the information is transmitted from the mobile device to the target cell.

11. The method according to claim 9 , wherein the information is transmitted in a history list of the mobile device, and wherein the handover from the target cell back to the source cell is made less likely if the second last visited cell in the history list is the source cell.

12. The method according to claim 1 , wherein additional information is transmitted during the handover procedure triggered by the second handover trigger signal from the source cell to the target cell, the additional information comprising:

the second threshold, and/or

the traffic load in the source cell;

wherein the target cell determines to accept the handover using the second threshold and/or the traffic load in the source cell.

13. A base station apparatus comprising:

a processor configured to

configure an associated mobile device to transmit a first handover trigger signal to a source cell being served by the base station apparatus, when a difference between a signal strength of an associated target cell and a signal strength of the source cell as measured by the mobile device is above a first threshold;

receive the first handover trigger signal from the mobile device;

determine a cell traffic load in the source cell;

in response to the cell traffic in the source cell being above a cell traffic threshold, in addition to the configuration regarding the first handover signal and the first threshold, configure the mobile device to transmit a second handover trigger signal to the source cell in response to a difference between a signal strength of the target cell and a signal strength of the source cell as measured by the mobile device being above a second threshold, wherein the first threshold is larger than the second threshold;

receive the second handover trigger signal from the mobile device; and,

store information about the mobile device that the handover has been performed from the source cell to the target cell after reception of the second handover trigger signal, in the case that the handover has been performed from the source cell to the target cell after reception of the second handover trigger signal, thereby recording an indication that the handover from the source cell to the target cell has occurred; and

make a further handover of the mobile device from the target cell back to the source cell less likely based on the recorded indication.

14. A non-transient computer-readable storage medium comprising instructions that when executed by a base station apparatus cause the base station apparatus to perform the following:

configuring an associated mobile device to transmit a first handover trigger signal to a source cell served by the base station, when a difference between a signal strength of an associated target cell and a signal strength of the source cell as measured by the mobile device is above a first threshold;

determining a cell traffic load in the source cell;

in response to the cell traffic load in the source cell being above a cell traffic threshold, in addition to the configuration regarding the first handover and first threshold, configuring the mobile device to transmit a second handover trigger signal to the source cell, in response to a difference between a signal strength of the target cell and a signal strength of the source cell as measured by the mobile device being above a second threshold, wherein the first threshold is larger than the second threshold; and,

storing information about the mobile device that the handover has been performed from the source cell to the target cell after reception of the second handover trigger signal, in response to the handover being performed from the source cell to the target cell after reception of the second handover trigger signal, thereby recording an indication that the handover from the source cell to the target cell has occurred; and

making a further handover of the mobile device from the target cell back to the source cell less likely based on the recorded indication.