A communication system is described in which user plane communication and control plane communication for a particular mobile communication device can be split between a base station that operates a small cell and a macro base station. Appropriate security for the user plane and control plane communications is safeguarded by ensuring that each base station is able to obtain or derive the correct security parameters for protecting the user plane or control plane communication for which it is responsible.

One embodiment of the present invention provides an apparatus comprising a transceiving unit and a control unit, and a communication method using the same, wherein the transceiving unit is configured to perform communication with at least one network node in a macro cell, the macro cell comprising at least one small cell and communicating in an FDD mode, and wherein the control unit is configured to control the small cell to communicate in a TDD mode, generate control information for preventing the occurrence of handover when a terminal moves between the small cells within the macro cell, and perform control to transmit the control information to the terminal.

Apparatuses, methods, and systems are disclosed for determining data available for transmission. One method includes associating a packet data convergence protocol entity with a first radio link control entity and a second radio link control entity belonging to two different cell groups. The method includes determining an amount of data available for transmission, the amount of data available for transmission including packet data convergence protocol data and radio link control data pending for initial transmission in the first radio link control entity and the second radio link control entity. The method includes comparing the amount of data available for transmission with a threshold. The method includes submitting the packet data convergence protocol data to a first radio link control entity in response to the amount of data available for transmission being below the threshold.

A base station of a dual connectivity cellular network is provided. The base station provides a first wireless connectivity of a first regulated wireless communication standard to a user equipment (UE) of a cellular network via a master node of the base station. User plane data is forwarded to the UE through the master node according to a first user plane path. The base station requests a secondary node to provide a second wireless connectivity of a second regulated wireless communication standard to the UE. When the master node is configured by a first configuration, the user plane data is forwarded to the UE through the secondary node according to the second user plane path that is established with the cellular network. When the master node is configured by a second configuration, the user plane data is forwarded to the UE through the secondary node according to the first user plane path.

For switching between packet duplication operating modes, methods, apparatus, and systems are disclosed. One apparatus includes a processor and a transceiver that communicates with a mobile communication network via a radio bearer. The processor determines whether PDCP packet duplication associated with the PDCP protocol entity is to be activated and, if so, communicates with a mobile communication network according to a packet duplication mode of operation. Otherwise, the processor determines whether a split threshold value of the PDCP protocol entity is set to a predefined value, communicates with the mobile communication network according to a first split bearer mode of operation in response to determining that the split threshold value is set to the predefined value, and communicates with the mobile communication network according to a second split bearer mode of operation in response to determining that the split threshold value is not set to the predefined value.

Apparatuses, methods, and systems are disclosed for determining data available for transmission. One method includes associating a packet data convergence protocol entity with a first radio link control entity and a second radio link control entity belonging to two different cell groups. The method includes determining an amount of data available for transmission, the amount of data available for transmission including packet data convergence protocol data and radio link control data pending for initial transmission in the first radio link control entity and the second radio link control entity. The method includes comparing the amount of data available for transmission with a threshold. The method includes submitting the packet data convergence protocol data to a first radio link control entity in response to the amount of data available for transmission being below the threshold.

There are provided measures for improvements in small cell mobility with dual/multi connectivity. Such measures exemplarily comprise terminating at least one control plane signaling connection from said terminal for said at least first network access entity and second network access entity, maintaining a terminal related access stratum context commonly for radio accesses of said terminal to said at least first network access entity and second network access entity, and initiating switching of said radio access of said terminal from said first network access entity to said second network access entity for user plane data transfer with said control plane signaling connection for said second network access entity being applied unchanged, thereby providing, in a control plane for a terminal, connection management for at least a first network access entity and a second network access entity, wherein said at least first network access entity and second network access entity providing radio access for user plane data transfer for said terminal, wherein said terminal being capable of having radio access to said at least first network access entity and second network access entity for user plane data transfer.

A service continuity implementation method, a device, and a service continuity implementation system, to ensure service continuity in a handover process, where the method includes: selecting, by a session management function entity, a target user plane function entity to serve a terminal; sending, by the session management function entity, a first message to a control device; receiving, by the session management function entity, indication information of a first application server (AS) from the control device; and sending, by the session management function entity, a first routing rule to the target user plane function entity based on the indication information of the first AS, where the first routing rule specifies that data whose destination address is an address of the first AS is to be sent to the first AS.

Apparatuses, methods, and systems are disclosed for determining data available for transmission. One method includes associating a packet data convergence protocol entity with a first radio link control entity and a second radio link control entity belonging to two different cell groups. The method includes determining an amount of data available for transmission, the amount of data available for transmission including packet data convergence protocol data and radio link control data pending for initial transmission in the first radio link control entity and the second radio link control entity. The method includes comparing the amount of data available for transmission with a threshold. The method includes submitting the packet data convergence protocol data to a first radio link control entity in response to the amount of data available for transmission being below the threshold.

A communication device for handling a bearer type change comprises at least one storage device for storing instructions and at least one processing circuit coupled to the at least one storage device. The at least one processing circuit is configured to execute the instructions stored in the at least one storage device. The instructions comprise receiving a first RRC message from a first BS; transmitting a first RRC response message to the first BS; establishing a PDCP entity; transmitting a first plurality of PDCP SDUs to the first BS; receiving a second RRC message from the first BS, wherein the second message configures the MCG bearer type to a SCG bearer type or a split bearer type; transmitting a second RRC response message to the first BS; reconfiguring the PDCP entity; and transmitting a second plurality of PDCP SDUs to a second BS when connecting to the first BS.