TECHNICAL FIELD

The disclosure relates to a method and system for providing communication in a wireless communication network and, in particular, to a method and system for providing communication to a terminal in a dual connectivity mode.

BACKGROUND ART

To meet the increased demand for wireless data traffic since the deployment of 4G communication systems, efforts have been made to develop an improved 5G or pre-5G communication system. Therefore, the 5G or pre-5G communication system is also called a “Beyond 4G Network” or a “Post LTE System”. Implementation of the 5G communication system in higher frequency (mmWave) bands, e.g., 60 GHz bands, is being considered in order to accomplish higher data rates. To decrease propagation loss of radio waves and increase the transmission distance, beamforming, massive multiple-input multiple-output (MIMO), Full Dimensional MIMO (FD-MIMO), array antenna, analog beam forming, and large scale antenna techniques are being discussed for the 5G communication system. In addition, in the 5G communication system, there are developments under way for system network improvement based on advanced small cells, cloud Radio Access Networks (RANs), ultra-dense networks, device-to-device (D2D) communication, wireless backhaul, moving network, cooperative communication, Coordinated Multi-Points (CoMP), reception-end interference cancellation, and the like. In the 5G system, Hybrid FSK and QAM Modulation (FQAM) and sliding window superposition coding (SWSC) as advanced coding modulation (ACM) and filter bank multi carrier (FBMC), non-orthogonal multiple access (NOMA), and sparse code multiple access (SCMA) as advanced access technology have been developed.

The Internet, which is a human centered connectivity network where humans generate and consume information, is now evolving into the Internet of Things (IoT) where distributed entities, such as things, exchange and process information without human intervention. The Internet of Everything (IoE), which is a combination of IoT technology and Big Data processing technology through connection with a cloud server, has emerged. As technology elements, such as “sensing technology”, “wired/wireless communication and network infrastructure”, “service interface technology”, and “security technology” have been demanded for IoT implementation, recently there has been research into a sensor network, Machine-to-Machine (M2M) communication, Machine Type Communication (MTC), and so forth. Such an IoT environment may provide intelligent Internet technology services that create new values for human life by collecting and analyzing data generated among connected things. The IoT may be applied to a variety of fields including smart home, smart building, smart city, smart car or connected car, smart grid, health care, smart appliances, and advanced medical services through convergence and combination between existing Information Technology (IT) and various industrial applications.

In line with these developments, various attempts have been made to apply the 5G communication system to IoT networks. For example, technologies such as a sensor network, Machine Type Communication (MTC), and Machine-to-Machine (M2M) communication may be implemented by beamforming, MIMO, and array antennas. Application of a cloud Radio Access Network (RAN) as the above-described Big Data processing technology may also be considered to be an example of convergence between the 5G technology and the IoT technology.

In a wireless communication network, a terminal may be in a state of being connected to two different base stations, i.e., dual connectivity state. Dual connectivity is useful for various purposes such as boosting the data rate of the terminal. In the dual connectivity mode, the terminal may be connected to two or more base stations (or access points equivalent thereto) belonging to the same network or heterogeneous networks.

In the dual connectivity mode, the network and the terminal may operate in association with a master cell belonging to a certain base station (or equivalent thereto) and a secondary cell belonging to the same base station as the master cell or a different base station (or equivalent thereto). As the terminal in the dual connectivity mode moves, the master cell may be changed, or the secondary cell is added, deleted, or modified. In this case, the terminal and the network have to perform a secondary cell release and addition procedure.

The movement of the terminal may cause change of the master cell while maintaining the secondary cell. According to the current standard, if the movement of the terminal causes change of the master cell or addition/deletion/modification of the secondary cell, it is inevitable for a secondary cell release and addition procedure to be performed. However, if the secondary cell release and addition procedure is performed unnecessarily, this is likely to cause user data loss or service delay. In particular, the result of a service breakdown or delay caused by performance of such an unnecessary procedure is significant service quality degradation for users who are consuming a real-time or pseudo real-time data service. Particularly in inter-radio access technology dual connectivity (inter-RAT DC) for an LTE base station as the master cell and a 5G base station as the secondary cell, if the secondary cell is in use for providing a massive data service, a service delay is likely to cause significant service breakdown.

The disclosure presents research conducted with the financial support of the “Government-wide Giga KOREA project” led by the Ministry of Science, ICT, and Future Planning in 2017.

DISCLOSURE OF INVENTION

Technical Problem

The disclosure provides seamless data transmission/reception methods and apparatuses of a terminal in a dual connectivity mode in a wireless communication system.

The disclosure also provides methods and devices for reducing unnecessary secondary cell release and addition operations.

The disclosure also provides methods and apparatuses for utilizing resources efficiently by reducing unnecessary secondary cell release and addition operations.

The disclosure also provides methods and apparatuses for improving service quality by reducing unnecessary secondary cell release and addition operations.

The disclosure also provides methods and apparatuses for reducing power consumption of a terminal by reducing unnecessary secondary cell release and addition operations.

Solution to Problem

According to a disclosed embodiment, a method for a master node control plane to provide dual connectivity to a user terminal in a wireless communication network includes transmitting a secondary node addition request message to a secondary control plane based on a user terminal in an RRC connected state to the master node control plane needing dual connectivity, transmitting an RRC connection reconfiguration message to the user terminal based on receiving a secondary node addition request response message from the secondary control plane, transmitting a secondary node reconfiguration complete message to the secondary control plane based on receiving an RRC connection reconfiguration complete message from the user terminal, and performing a path update procedure for the user terminal with an access and mobility function entity.

According to another disclosed embodiment, a method for a secondary node control plane to provide dual connectivity to a user terminal in a wireless communication network includes receiving a secondary node addition request message for a user terminal in a connected state to a master node control plane from the master node control plane, generating and transmitting a secondary node addition request response message to the master node control plane in response to the secondary node addition request message, and performing a random access procedure with the user terminal based on receiving a secondary node reconfiguration complete message from the master node control plane.

According to another disclosed embodiment, a method for a common anchored user plane to provide dual connectivity to a user terminal in a wireless communication network includes maintaining a bearer configured to the user terminal based on receiving a radio bearer control request message including a keep indicator from a master node control plane or a secondary node control plane for the user terminal in an RRC connected state to the master node control plane, generating and transmitting a radio bearer control response message to the control plane that transmitted the radio bearer control request message, generating and transmitting a radio bearer resume response message to the master node control plane and the secondary node control plane based on receiving a radio bearer resume request message from the master node control plane and the secondary node control plane, performing a bearer path update for transmitting data from an access and mobility function entity to the user terminal, and transmitting user data to the user terminal through an updated bearer.

According to another disclosed embodiment, a wireless communication system for supporting dual connectivity includes a plurality of master radio communication units that have respective communication areas equal or different in size and support the dual connectivity for at least one user terminal and that include at least part of a communication area of at least one secondary node radio communication unit, a common anchored user plane configured to communicate user data with the plurality of radio communication units, forward the user data to the user terminal located in the communication area of one of the plurality of radio communication units, and perform an operation for maintaining a bearer for transmitting the user data to the user terminal for at least one of secondary node addition, secondary node release, secondary node's master node modification, secondary node change, handover, bearer type change, and inter-master node handover, a secondary node control plane configured to control the radio communication unit of the secondary node to transmit the user data via the common anchored user plane and maintain the bearer for transmitting the user data to the user terminal for at least one of the secondary node addition, secondary node release, secondary node's master node modification, secondary node change, handover, bearer type change, and inter-master node handover, and a master node control plane configured to control the plurality of master radio communication units to transmit the user data vis the common anchored user plane and maintain the bearer for transmitting the user data to the user terminal for at least one of the secondary node addition, secondary node release, secondary node's master node modification, secondary node change, handover, bearer type change, and inter-master node handover.

Advantageous Effects of Invention

The disclosed embodiments are advantageous in terms of providing a terminal in a dual connectivity mode with a seamless data communication service and improving resource utilization efficiency by reducing unnecessary secondary cell release and addition operations in a wireless communication system. The disclosed embodiments are also advantageous in terms of providing a service seamlessly, improving a service quality, and reducing power consumption of a terminal by reducing unnecessary secondary cell release and addition operations.

