KR20110046817A - Mobile Communication System and Method for Implementing HandOver of User Equipment - Google Patents

Abstract

PURPOSE: A mobile communication system and handover method of a user device using the same are provided to maximally save a cost according to a design of a communication network. CONSTITUTION: An FDD(Frequency Division Duplex) mobile communication network enable a communication of an FDD and has a base station(110). A first TDD mobile communication network(200) has a communication available area of the small size by contrasting with the FDD mobile communication network. The first TDD mobile communication is available for communication of a TDD by enabling the FDD mobile communication network and a partial area to be overlapped.

Description

Mobile communication system and method for handover of user equipment using the same {Mobile Communication System and Method for Implementing HandOver of User Equipment}

An embodiment of the present invention relates to a mobile communication system and a handover method of a user device using the same, and more particularly, to strengthen the third generation partnership project long term evolution standard, that is, an LTE system. In the mobile communication system and a handover method of a user device using the same, a handover can be performed in the LTE mode and a handover in the LTE mode can be supported by generating protocol messages therefor. Related.

Conventional mobile communication systems are well known. In order to provide the global connectivity of wireless systems, many standards of standards have been developed and are being implemented, among which the General Purpose System for Mobile Communications (GSM) is the widely used standard. This is considered the so-called second-generation mobile radio system standard, followed by a 2.5 generation revision.

General Packet Radio Service (GPRS) and EDGE are examples of 2.5G technologies that provide relatively fast data services over (2G) GSM networks. Each of these standards sought to enhance the previous standard with additional features and enhancements. In January 1998, the European Telecommunications Standard Institute-Special Mobile Group (ETSI SMG), part of the European Telecommunications Standards Association, planned for wireless access to a third-generation wireless system called Universal Mobile Telecommunications Systems (UMTS). Agree on To further implement the UMTS standard, 3GPP was formed in December 1998. 3GPP continues to work on generic third generation mobile radio standards.

1 is a diagram illustrating a typical UMTS system structure of a conventional 3GPP.

As shown in FIG. 1, the UMTS network structure includes a Core Network (CN) interconnected with a UTMS Terrestrial Radio Access Network (UTRAN) via an interface known as Iu. The UTRAN (UMTS Terrestrial Radio Access Network) uses mobile communication services through Wireless Transmit Receive Units (WTRUs), known as User Equipments (UEs) in 3GPP, via a radio interface known as Uu. It is configured to provide.

The UTRAN has one or more Mobile Network Controllers (RNCs) and base stations that collectively provide geographical coverage for mobile communication with UEs known as Node Bs of 3GPP, and one or more Node Bs to the Iubs of 3GPPs. It is connected to each RNC via a known interface. The UTRAN has a plurality of Node B groups connected to different RNCs, and when more than one RNC is provided to the UTRAN, inter-RNC communication is performed via an Iur interface.

Communication out of network components is performed by the Node B via the Uu interface at the user level, and by the CN via multiple CN connections to external systems at the network level.

In general, the primary function of a base station, such as Node B and access point, is to provide a wireless connection between the network of base stations and the WTRU. Typically, a base station sends out a generic channel signal that allows an unconnected WTRU to be synchronized to the base station's timing, and in 3GPP, Node B performs a physical radio connection with the UE. Node B receives a signal from the RCN via the Iub interface and the RNC controls the signal transmitted by Node B via the Uu interface.

The CN is responsible for routing information to the correct destination. For example, the CN sends voice traffic received by UMTS via one of the Node Bs as packet data allocated from the UE to the public switched telephone network (PSTN) or the Internet. In 3GPP, the CN consists of six main components: 1) serving GPRS support node, 2) gateway GPRS support node, 3) border gateway, 4) visitor location register, 5 A) a mobile service exchange center, and 6) a gateway mobile service exchange center.

The serving GPRS support node provides access to a packet switched domain, such as the Internet. The gateway GPRS support node is a gate node for connection to another network. All data traffic going to another operator's network or the Internet goes through the gateway GPRS support node. The perimeter gateway acts as a firewall to prevent intruders outside the network from attacking subscribers within the network area. The visitor location register is a currently provided network 'copy' of the subscriber data needed to provide the service. This information is initially obtained from the database managing the mobile subscriber. The Mobile Service Switching Center is responsible for the 'changed circuit' connection from the UMTS terminal to the network. The gateway mobile service switching center performs delivery of necessary functions based on the current location of the subscriber. The gateway mobile service switching center also receives and manages connection requests from subscribers to external networks.

The RNC generally controls the internal functions of the UTRAN. The RNC also provides a relay service with a local element via the Uu interface connection to Node B and an external element via the connection between the CN and an external system, for example via an international call to a mobile phone of a domestic UMTS.

Typically, the RNC oversees multiple base stations, manages radio resources within the geographic area of radio service coverage serviced by Node B, and controls physical radio resources for the Uu interface. In 3GPP, the Iu interface of the RNC provides two connections to the CN. One is the connection to the domain being packet switched and the other is the connection to the domain being circuit switched. Another important feature of RNC is reliability and integrity protection. In communication systems such as 3GPP Time Division Duplex (TDD) and Frequency Division Duplex (FDD) systems, multiple shared and dedicated channels for data at various rates are combined for transmission. Almost all mobile communication systems use two different channels for uplink (UL) and downlink (DL) traffic.

In a TDD type system, the UL and DL channels are in the same frequency domain. Separation of the UL and DL channels occurs in the time domain. Therefore, for a particular frequency carrier, the specific link direction of that frequency carrier alternates between UL and DL depending on whether the UL or DL traffic is currently being processed on one frequency carrier. In contrast, in an FDD type system, two frequency bands are used for the UL and DL connections. Most systems, including conventional cordless phones, North American cellular radios, microwave point-to-point radios and satellite systems, implement FDD-type technology.

With the development of mobile communication systems, the types of traffic handled by such systems have evolved to include not only voice communications, but also various types of data transmission. For example, multimedia data transmission over a mobile communication system often causes asymmetry in the traffic load between UL and DL connections.

In this regard, both TDD and FDD type systems increase overlap in the coverage area available to wireless users. In a TDD type system, the number of UL channels and DL channels is dynamically adjusted according to traffic conditions at specific times and places. Therefore, TDD type systems are more suitable for handling traffic with high data rates that are asymmetric (or otherwise unbalanced). On the other hand, the FDD system has an advantage over the TDD type system in dealing with a fixed data rate service by appropriately lowering the data rate like voice traffic due to predetermined allocation of UL and DL resources.

By the way, radio resource management between a TDD type system and an FDD type system is individually performed in each system type according to their own allocation method. This configuration hinders potential optimizations that can be made by integrating resource allocation between TDD and FDD in a mobile communication system. Therefore, there is a need to integrate radio resource management between TDD and FDD in a mobile communication system.

For example, when the mobile communication system cannot provide information for handover between TDD and FDD, the user device, i.e., the terminal, is disconnected or disconnected from the LTE in the existing mode. Will occur.

And radio resource management integration between TDD and FDD increases the design cost of a mobile communication system depending on how to integrate radio resource management between the TDD and FDD. This will soon lead to increased costs for mobile operators.

Accordingly, a first object of an embodiment of the present invention is to provide a mobile communication system for enabling handover between FDD and TDD, and a second object is to enable handover between FDD and TDD of a user device, that is, FDD and TDD dual mode terminal. The present invention provides a handover method of a user device using a mobile communication system.

A mobile communication system according to an embodiment of the present invention has an FDD mobile communication network having a base station and capable of FDD communication, a small communication area compared to the FDD mobile communication network, and overlaps the FDD mobile communication network with at least a partial region. At least one first TDD mobile communication network capable of communicating with the TDD, and the FDD mobile communication network or the first TDD mobile communication network according to information on the FDD and the TDD included in the protocol message and communicating with the base station through a protocol message; It characterized in that it comprises a user device that is a handover between each other.

In addition, a handover method of a user equipment using a mobile communication system according to an embodiment of the present invention has a base station and a communication area of a small size compared to the FDD mobile communication network and the FDD mobile communication network capable of FDD communication, A mobile communication system including at least one first TDD mobile communication network capable of overlapping an FDD mobile communication network with at least a partial region, and capable of handover between the FDD mobile communication network or the first TDD mobile communication network. The measurement check step of instructing the base station to measure the FDD or the TDD from the base station and the measurement of the adjacent FDD or the TDD as received from the measurement check step. A measurement report step of reporting measurement values to a base station, and the base station Selecting the best cell in the FDD or TDD for handover according to the measurement value, characterized by comprising a RRC (Radio Resource Control) connection reconfirmed step of instructing the user equipment to hand-over the serving cells.

As a result of the above configuration and method, an embodiment of the present invention can be designed by arranging FDD LTE and TDD LTE in consideration of LTE frequency allocation cost, geographic information, traffic requirement, peripheral interference, etc. in LTE development. Therefore, the cost according to the design of the communication network will be saved as much as possible.

In addition, since FDD LTE and TDD LTE overlap each other, a protocol message related to mobility in LTE is generated accordingly, thereby enabling efficient handover between LTE in different modes, thereby enabling communication connection when the user equipment is used. Will not be broken.

Furthermore, since the protocol message is changed in software (S / W) without changing the hardware (H / W) of the system for handover of the user device, the execution of the system can be simplified.

Hereinafter, exemplary embodiments of the present invention will be described in detail. In adding reference numerals to the elements of each drawing, it should be noted that the same elements may be denoted by the same reference numerals as much as possible because they may be displayed on different drawings. In addition, in describing the present invention, when it is determined that the detailed description of the related well-known configuration or function may obscure the gist of the present invention, the detailed description thereof will be omitted.

In addition, in describing the component of this invention, terms, such as 1st, 2nd, A, B, (a), (b), can be used. These terms are only for distinguishing the components from other components, and the nature, order or order of the components are not limited by the terms. If a component is described as being "connected", "coupled" or "connected" to another component, that component may be directly connected to or connected to that other component, but there may be another configuration between each component. It is to be understood that the elements may be "connected", "coupled" or "connected".

FIG. 2 is a diagram illustrating a mobile communication system according to an exemplary embodiment of the present invention, and FIG. 3 is a diagram illustrating an application example of a TDD LTE relay in the FDD-based communication network illustrated in FIG. 2.

As shown in FIG. 2, the mobile communication system according to the embodiment of the present invention has a wide communication area of a relatively superior technology type (compared to the first and second TDD LTE networks) and enables the FDD LTE communication of FDD LTE. 100 and a plurality of first TDD LTE networks (TDD-LTE in Hot Zone) 200 in which at least a portion of the FDD LTE communication network 100 overlaps and is available at a higher data rate and enables LTE communication of TDD. consist of. In this case, the mobile communication network system may include a second TDD LTE communication network 220 having a communicable area of the same size as the first TDD LTE communication network and overlapping at least some areas, and the FDD LTE and the TDD LTE may include at least one cell. Can be done. In addition, a hot zone herein indicates an area available at a higher data rate in the FDD LTE communication network 100 and may be represented by a network hole (N / W hole).

In more detail, TDD compared to FDD uses the same frequency band without distinguishing between UL and DL, but distinguishes by time, thereby showing strength in channel estimation, which is important in broadband high-speed data communication. As a result, redundancy for channel estimation can be reduced, for example, TDD is more efficient than FDD in buildings or short distances. In addition, TDD is considered in the development of communication network because the frequency acquisition cost is relatively much lower than FDD.

For example, if an operator or operator acquires four frequencies, instead of using all four frequencies in all regions, only one to three macros are used, but high-traffic hotspots or dense sites All four frequencies may be used in the back. Therefore, the operator obtains only two or three frequencies for FDD, and the other one or two frequencies acquire frequencies for TDD. For this purpose, it is desirable to deploy TDD LTE in a hot spot or building when deploying a communication network.

Furthermore, since the mobile communication system according to the embodiment of the present invention uses FDD LTE and TDD LTE for a relay system or the like for connection between individual users, it can be sufficiently considered. I will not.

Meanwhile, in the mobile communication system according to the embodiment of the present invention, as shown in FIG. 3, a first TDD in which at least a portion of the base station 110 and the FDD LTE communication network 100 are installed in the FDD LTE communication network 100 overlaps. At least one user device 300 located in the LTE communication network 200 and communicating with the base station 110, and provided in the first TDD LTE communication network 200 to relay communication between the base station 110 and the user device 300 It may include a relay 210.

The base station 110 in the FDD LTE communication network 100 is included in an Evolved Universal Mobile Telecommunication System (EUMTS) and may be applied to an Evolved Universal Terrestrial Radio Access Network (EUTRAN) system, which is a key control node in the LTE access network. It may also be linked with a mobility management entity (MME) of the network.

Accordingly, the MME controls the user device 300 to enable handover between the FDD LTE communication network 100 or the first TDD LTE communication network 200. However, although the embodiment of the present invention has been described taking an MME that uses LTE as an example, it will not be particularly limited thereto.

In addition, user equipment 300 may include, for example, a mobile station such as a portable terminal, a fixed or mobile subscriber device, a pager, or other type of device operable in a wireless environment. . In this case, the user device 300 is preferably an FDD and TDD LTE dual mode terminal.

The relay 210 may be disposed in at least one of a boundary area where the FDD LTE communication network 100 and the first TDD LTE communication network 200 overlap each other and a non-boundary area that do not overlap each other, and perform high-speed data transmission. For the purpose of this purpose, it is introduced for the purpose of coverage extension and transmission rate improvement at the cell edge. In this case, the connection interface between the relay 210 and the user device 300, that is, the terminal may be a Uu interface, and the connection interface between the relay 210 and the base station 110 may be defined as an Un interface. In the example, the definition is the same.

4 is a flowchart illustrating a handover process between an RRC connected terminal and a system in an LTE system, and FIG. 5 is a diagram illustrating a protocol message of a measurement confirmation step of FIG. 4. 6 is a diagram illustrating a protocol message of the measurement report step of FIG. 4, and FIG. 7 is a diagram illustrating a protocol message of the RRC connection reconfirmation step of FIG. 4.

As shown in FIG. 4, a handover process between a UE and a system in an RRC (Radio Resource Control) connected state in an LTE system according to an embodiment of the present invention is performed in 1) a user equipment at a base station (more precisely an eNodeB). A measurement configuration step, a 2) measurement report step from the user equipment to the base station, and 3) an RRC connection reconfiguration step from the base station to the user equipment.

Here, 1) in the step of checking the measurement from the base station to the user device, the system, that is, the RNC, requests the terminal through a message, an object necessary for determining a handover of the user device, that is, the terminal. At this time, the terminal is to command to measure for both FDD LTE and TDD LTE.

FIG. 5 shows a protocol message for a measurement confirming step for performing a function thereof, and the frequency and bandwidth of an LTE cell to be measured in a 'Measurement Object E-UTRAN' field in a measurement confirmation. (bandwidth), measurement triggering conditions, and the like, and furthermore, by including information about the FDD or TDD mode in the field of measurement EUTRAN, i.e., MeasObjectEUTRA, when the system requests measurement from the terminal, TDD LTE can be commanded to distinguish and measure.

In addition, 2) the measurement reporting step from the user equipment to the base station is measured by the terminal and the reporting triggering conditions (receiving triggering condition) received through the above measurement step to report the information on the cell and the neighboring cell to the system Done. At this time, the measurement value is reported to the system by measuring both adjacent FDD and TDD LTE cells as commanded in the measurement confirmation step. Here, the FDD and TDD LTE is composed of at least one cell.

6 shows a protocol message for a measurement report step for performing this, wherein a user device, i.e., a terminal, measures information of a cell and reports it to a system, and LTE (E-UTRA) and WCDM are included in a Measurement Report '' Measurement Result message. (UTRA), GSM (GERAN), CDMA2000 system will include a field to identify. At this time, the protocol message for measurement report includes information on FDD or TDD in the Measurement Result field so that the terminal can distinguish and report FDD LTE and TDD LTE when reporting the measured value to the system.

3) In the step of re-confirming the RRC connection from the base station to the user equipment, the system, which has determined whether the handover is performed through the measurement report step, instructs the terminal to perform the handover. In this case, the system selects an optimal cell for handover in consideration of traffic load or interference, and instructs the terminal to handover to an optimal cell, for example, a TDD LTE hot zone. .

FIG. 7 illustrates a protocol message of an RRC connection re-establishment step for performing such a command scheme, and includes 'MobilityControlInfo' including information on a target cell such as a physical cell ID, a carrier frequency, and a bandwidth required for handover. In this case, the system determines a handover to another cell in LTE of the terminal through the measurement reporting step reported by the terminal, and then informs the target cell information in the RRC Connection Reconfiguration '' MobilityControlInfo message. Will be. In this case, the protocol message of the RRC connection reconfirmation step includes information on the mode FDD or TDD in the MobilityControlInfo message included in the RRC connection reconfirmation, so that the FDD and TDD as well as information such as frequency when the system delivers the target cell information to the terminal. The distinction is to LTE.

As described above, according to the configuration of the mobile communication network according to the embodiment of the present invention, the cost saving effect by providing an optimal design and deployment method for integrating the mobile communication network of FDD LTE and TDD LTE to the developer or operator of the communication network Will bring it. In addition, according to the configuration of the mobile communication network, the handover for communication between the system, that is, the base station (or MME) and the user device will be natural, thereby improving the call quality.

In addition, the terms "comprise", "comprise" or "having" described in the specification mean that a corresponding component may be included unless otherwise stated, and thus, other components are excluded. It should be construed that it may further include other components. All terms, including technical and scientific terms, have the same meanings as commonly understood by one of ordinary skill in the art unless otherwise defined. Terms used generally, such as terms defined in a dictionary, should be interpreted to coincide with the contextual meaning of the related art, and shall not be interpreted in an ideal or excessively formal sense unless explicitly defined in the present invention.

The foregoing description is merely illustrative of the technical idea of the present invention, and various changes and modifications may be made by those skilled in the art without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are not intended to limit the technical idea of the present invention but to describe the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. The protection scope of the present invention should be interpreted by the following claims, and all technical ideas within the equivalent scope should be interpreted as being included in the scope of the present invention.

As described above, the embodiment of the present invention can be applied to the mobile communication system as a whole to save the cost according to the mobile communication system design, and according to the design of the handset between the FDD and TDD of the user device, for example, the portable terminal. By enabling over, call quality will be improved.

1 is a diagram showing a typical UMTS system structure of a conventional 3GPP

2 illustrates a communication network structure according to an embodiment of the present invention.

FIG. 3 is a diagram illustrating an example of using a TDD LTE relay in the FDD-based communication network illustrated in FIG. 2.

4 is a flowchart illustrating a handover process between a UE and a system in an RRC connected state in an LTE system;

5 is a diagram illustrating a protocol message of a measurement confirmation step of FIG. 4.

6 is a diagram illustrating a protocol message of a measurement report step of FIG. 4.

7 is a diagram illustrating a protocol message for an RRC connection reconfirmation step of FIG. 4.

Claims (10)

An FDD mobile communication network having a base station and capable of communicating a frequency division duplex (FDD); At least one first TDD mobile communication network having a small size capable of communicating with the FDD mobile communication network, wherein at least a partial region overlaps with the FDD mobile communication network to enable time division duplex (TDD) communication; And A user device communicating with the base station through a protocol message and having a handover between the FDD mobile communication network or the first TDD mobile communication network by information on the FDD and TDD included in the protocol message; Mobile communication system comprising a. The method of claim 1, The user device is a mobile communication system, characterized in that the FDD and TDD dual mode terminal. The method of claim 1, And the base station is connected to a mobility management entity (MME) included in an evolved terrestrial radio access network (EUTRAN), which serves as a control node of the EUTRAN, wherein the MME controls the handover. The method of claim 3, And a second TDD mobile communication network having a communicable area of the same size as the first TDD mobile communication network and overlapping at least some areas. The method of claim 4, wherein At least one of the first TDD mobile communication network and the second TDD mobile communication network includes a relay for relaying communication between the user device and the MME. An FDD mobile communication network having a base station and capable of communicating a frequency division duplex (FDD), a communicable area having a smaller size compared to the FDD mobile communication network, and overlapping the FDD mobile communication network with at least a partial region; A mobile communication including at least one first TDD mobile communication network capable of communicating time division duplex (TDD), and a user device capable of handover between the FDD mobile communication network or the first TDD mobile communication network. In the system, A measurement checking step of instructing the base station to make a measurement for both FDD and TDD from the base station; A measurement report step of measuring all adjacent FDDs or TDDs as received in the measurement checking step and reporting the measured values from the user equipment to the base station; And The base station selects an optimal cell in the FDD or TDD for handover according to the measurement value, and performs a radio resource control (RRC) re-confirmation step of instructing the user equipment to handover to the optimal cell. A handover method of a user device using a mobile communication system comprising. The method of claim 6, The base station is connected to a mobility management entity (MME) which is included in an evolved terrestrial radio access network (EUTRAN) and serves as a control node of the EUTRAN, wherein the MME controls handover of the base station. Handover method of the user device using the. The method of claim 6, The protocol message of the measurement confirmation step includes measurement configuration and measurement object EUTRA information, and further includes information on the LTE in the measurement confirmation and measurement object EUTRA information. A handover method of a user device using a mobile communication system. The method of claim 6, The protocol message of the measurement report step includes measurement report information, and the measurement report information further comprises the information on the LTE handover method of a user device using a mobile communication system. The method of claim 6, The RRC connection reconfirmation step includes mobility control information (MobilityControlInfo) having information of a target cell for handover, and further includes information on the LTE in the mobility control information. How to handover a device.

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