Uplink cell changes in a mobile communication network

A system comprising:

• a first radio base station;
• a second radio base station;
• and
• a user equipment (UE) wirelessly connectable to a cellular mobile communication network adapted to perform uplink cell change of the UE from the first radio base station to the second radio base station, wherein the UE is configured to:
• transmit multiple Internet Protocol (IP) packets each comprising one or more protocol data units (PDUs) to the first radio base station;
• receive one or more feedback indications from the first radio base station, each feedback indication indicating whether a corresponding PDU was successfully received by the first radio base station;
• transmit one or more retransmissions of at least one of the PDUs based on the received feedback indications;
• coordinate a time point for performing a cell change with controlling ongoing retransmissions of outstanding PDUs, where before performing the cell change, finalizing outstanding retransmissions of PDUs for all IP-packets where a complete IP-packet has been transmitted by continuing to make the retransmissions until either acknowledgments are received for the outstanding PDUs or a maximum number of retransmissions is reached for the outstanding PDUs, wherein for any of the IP packets where only parts of the PDUs have been transmitted then retransmissions are not performed for those IP packets;
• after the controlled ongoing retransmissions are performed, perform the cell change to the second radio base station and transmitting PDUs to the second radio base station starting from the first IP packet that was not delivered to the first radio base station, wherein the PDUs that were still outstanding after retransmissions at time of the cell change due to that the maximum number of retransmissions was reached are not transmitted to the second radio base station.

A method implemented by a user equipment (UE) wirelessly connectable to a cellular mobile communication network adapted to perform uplink cell change of the UE from a first radio base station to a second radio base station, the method comprising the steps of:

• transmitting multiple Internet Protocol (IP) packets each comprising one or more protocol data units (PDUs) to the first radio base station;
• receiving one or more feedback indications from the first radio base station, each feedback indication indicating whether a corresponding PDU was successfully received by the first radio base station;
• transmitting one or more retransmissions of at least one of the PDUs based on the received feedback indications;
• coordinating a time point for performing a cell change with controlling ongoing retransmissions of outstanding PDUs, where before performing the cell change, waiting until receiving feedback indications from all the outstanding PDUs and then performing the cell change regardless if the feedback indications are positive or negative, wherein the UE only waits for one feedback indication for each of the outstanding PDUs;
• and
• after performing the cell change to the second radio base station, transmitting the first IP packet that was not completely received in the first radio base station, where in case a negative feedback indication was received for at least one PDU carrying segments of an IP packet, the UE knows that this IP packet was not received completely in the first base station thus the UE can transmit the same IP packet to the second radio base station without risk for data duplication.

A system comprising:

• a first radio base station;
• a second radio base station;
• and
• user equipment (UE) wirelessly connectable to a cellular mobile communication network adapted to perform uplink cell change of the UE from the first radio base station to the second radio base station, wherein the UE is configured to:
• transmit multiple Internet Protocol (IP) packets each comprising one or more protocol data units (PDUs) to the first radio base station;
• receive one or more feedback indications from the first radio base station, each feedback indication indicating whether a corresponding PDU was successfully received by the first radio base station;
• transmit one or more retransmissions of at least one of the PDUs based on the received feedback indications;
• coordinate a time point for performing a cell change with controlling ongoing retransmissions of outstanding PDUs, where before performing the cell change, waiting until receiving feedback indications from all the outstanding PDUs and then performing the cell change regardless if the feedback indications are positive or negative, wherein the UE only waits for one feedback indication for each of the outstanding PDUs;
• and
• after performing the cell change to the second radio base station, transmit the first IP packet that was not completely received in the first radio base station, where in case a negative feedback indication was received for at least one PDU carrying segments of an IP packet, the UE knows that this IP packet was not received completely in the first base station thus the UE can transmit the same IP packet to the second radio base station without risk for data duplication.

A method implemented by a user equipment (UE) wirelessly connectable to a cellular mobile communication network adapted to perform uplink cell change of the UE from a first radio base station to a second radio base station, the method comprising the steps of:

• transmitting multiple Internet Protocol (IP) packets each comprising one or more protocol data units (PDUs) to the first radio base station, wherein each of the protocol data units (PDUs) is associated with an Internet Protocol (IP) packet;
• receiving one or more feedback indications from the first radio base station, each feedback indication indicating whether a corresponding PDU was successfully received by the first radio base station;
• transmitting one or more retransmissions of at least one of the PDUs based on the received feedback indications;
• adaptively choosing between behavior of a first process or a second process when coordinating a time point for performing a cell change with controlling ongoing retransmissions of outstanding PDUs;
• wherein the first process includes steps of:
• before performing the cell change, finalizing outstanding retransmissions of PDUs for all IP-packets where a complete IP-packet has been transmitted, by continuing to make the retransmissions until either acknowledgments are received for the outstanding PDUs or a maximum number of retransmissions is reached for the outstanding PDUs, wherein for any of the IP packets where only parts of the PDUs have been transmitted then retransmissions are not performed for those IP packets;
• and
• after the controlled ongoing retransmissions are performed, performing the cell change to the second radio base station and transmitting PDUs to the second radio base station starting from the first IP packet that was not delivered to the first radio base station, wherein the PDUs that were still outstanding after retransmissions at time of the cell change due to that the maximum number of retransmissions was reached are not transmitted to the second radio base station;
• wherein the second process includes steps of:
• before performing the cell change, waiting until receiving feedback indications from all the outstanding PDUs and then performing the cell change regardless if the feedback indications are positive or negative, wherein the UE only waits for one feedback indication for each of the outstanding PDUs;
• and
• after performing the cell change to the second radio base station, transmitting the first IP packet that was not completely received in the first radio base station, where in case a negative feedback indication was received for at least one PDU carrying segments of an IP packet, the UE knows that the same IP packet was not received completely in the first base station thus the UE can transmit the same IP packet to the second radio base station without risk for data duplication;
• and
• the adaptively choosing step includes:
• estimating an amount of radio resources and time needed to finalize outstanding retransmissions to the first radio base station by estimating at least one of a radio channel quality, an amount of energy that has already been transmitted and a number of active retransmission processes;
• estimating an amount of radio resources needed to transmit data to the second radio base station by estimating a radio channel quality to the second radio base station;
• and
• deciding to act according to the behavior of the first process or the second process based on results of the two estimating steps.

A system comprising:

• a first radio base station;
• a second radio base station;
• and
• a user equipment (UE) wirelessly connectable to a cellular mobile communication network adapted to perform uplink cell change of the UE from the first radio base station to the second radio base station, wherein the UE is configured to:
• transmit multiple Internet Protocol (IP) packets each comprising one or more protocol data units (PDUs) to the first radio base station;
• receive one or more feedback indications from the first radio base station, each feedback indication indicating whether a corresponding PDU was successfully received by the first radio base station;
• transmit one or more retransmissions of at least one of the PDUs based on the received feedback indications;
• adaptively choose between behavior of a first process or a second process when coordinating a time point for performing a cell change with controlling ongoing retransmissions of outstanding PDUs;
• wherein the first process includes steps of:
• before performing the cell change, finalizing outstanding retransmissions of PDUs for all IP-packets where a complete IP-packet has been transmitted, by continuing to make the retransmissions until either acknowledgments are received for the outstanding PDUs or a maximum number of retransmissions is reached for the outstanding PDUs, wherein for any of the IP packets where only parts of the PDUs have been transmitted then retransmissions are not performed for those IP packets;
• and
• after the controlled ongoing retransmissions are performed, performing the cell change to the second radio base station and transmitting PDUs to the second radio base station starting from the first IP packet that was not delivered to the first radio base station, wherein the PDUs that were still outstanding after retransmissions at time of the cell change due to that the maximum number of retransmissions was reached are not transmitted to the second radio base station;
• wherein the second process includes steps of:
• before performing the cell change, waiting until receiving feedback indications from all the outstanding PDUs and then performing the cell change regardless if the feedback indications are positive or negative, wherein the UE only waits for one feedback indication for each of the outstanding PDUs;
• and
• after performing the cell change to the second radio base station, transmitting the first IP packet that was not completely received in the first radio base station, where in case a negative feedback indication was received for at least one PDU carrying segments of an IP packet, the UE knows that this IP packet was not received completely in the first base station thus the UE can transmit the same IP packet to the second radio base station without risk for data duplication;
• and
• the adaptively choosing step includes:
• estimate an amount of radio resources and time needed to finalize outstanding retransmissions to the first radio base station by estimating at least one of a radio channel quality, an amount of energy that has already been transmitted and a number of active retransmission processes;
• estimate an amount of radio resources needed to transmit data to the second radio base station by estimating a radio channel quality to the second radio base station;
• and
• decide to act according to the behavior of the first process or the second process based on results of the two estimating steps.