Method and System for Transitioning Between Radio Access Technologies (RATS)

A wireless communications device having a first protocol stack for use with a first radio access technology, a second protocol stack for use with a second radio access technology, the first protocol stack comprising a reordering component associated with a first layer of the first protocol stack and arranged to implement a data reordering queue, and a processor operable according to a computer program to cause the wireless communications device to:

• determine that the device should perform a handover from the first radio access technology to the second radio access technology;
• in response to determining that the device should perform a handover and before handover commences:
• determine that data is present in a reordering queue implemented by the reordering component;
• and
• send the data present in the reordering queue to a second layer of the first protocol stack which is higher than the first layer of the first protocol stack;
• and
• thereafter attempt a handover from the first radio access technology to the second radio access technology.

A computer program product comprising program code stored on a non-transitory computer readable medium for use in a wireless communications device, the wireless communications device having a first protocol stack for use with a first radio access technology and a second protocol stack for use with a second radio access technology, the first protocol stack comprising a reordering component associated with a first layer of the first protocol stack and arranged to implement a data reordering queue, the computer program arranged, in use, to cause the wireless communications apparatus to:

• determine that the device should perform a handover from the first radio access technology to the second radio access technology;
• in response to determining that the device should perform a handover and before handover commences:
• determine that data is present in a reordering queue implemented by the reordering component;
• and
• send the data present in the reordering queue to a second layer of the first protocol stack which is higher than the first layer of the first protocol stack;
• and
• thereafter attempt a handover from the first radio access technology to the second radio access technology.