KR20090084384A - System for providing interworking heterogeneous network, and method therefor, and the recording media storing the program performing the said method - Google Patents

Abstract

A system for providing interworking heterogeneous network and a method thereof, and a recording media storing program performing the method are provided to process QoS(Quality of Service) negotiation and radio resource reservation prior to handover. A parameter at the physical layer or data link layer is extracted as a radio resource parameter(S400). An NDR(Net Data Rate) is calculated by GDR(Gross Data Rate), and a virtual NDR at the calculated NDR as described above is generated(S410). A valid NDR is calculated by a radio resource parameter which is provided by the opposite side network or a radio resource parameter extracted as described above(S425). If the valid NDR is greater than or same as the NDR or the virtual NDR, the radio resource reservation is performed using the radio resource parameter(S435).

Description

System for providing interworking heterogeneous network, and method therefor, and the recording media storing the program performing the said method

The present invention relates to a heterogeneous network interworking system, a method thereof, and a recording medium on which a program for implementing the method is recorded. More specifically, to negotiate seamless handover between heterogeneous networks (eg, 3G-LTE network and WiMAX network), QoS negotiation and radio resource reservation are preceded by the handover between the two networks. A heterogeneous network interworking system and method thereof, and a recording medium having recorded thereon a program for implementing the method.

In general, an orthogonal frequency division multiple access (OFDMA) time division duplex (TDD) frame structure used in WiMAX has the following configuration. First, there is a burst structure of each mobile node (MN) or a cyclic prefix (CP) for each symbol. Second, the bandwidth used by WiMAX is 10 MHz, and the number of sub-carriers is 1024. Third, the frequency spacing of each subcarrier is the bandwidth divided by the number of subcarriers, which is about 9.77 kHz. Fourth, there are 42 OFDMA symbols in one TDD frame. The period of each symbol is 115.2 ms, TTG (Transmit Transition Gap) is 121.2 ms, and Receive Transition Gap (RTG) is 40.4 ms. Therefore, the TDD frame period is 5 ms. Fifth, WiMAX slots can be used in Full Usage of Sub-Channels (FUSC) and Partial Usage of Sub-Channels (PUSC) in downlink, and use only PUSC in uplink. The number of subcarriers per symbol varies according to each method, and the bandwidth per subcarrier varies according to each method because the position and the number of pilots are different. Sixth, the downlink FUSC has 52 carriers and one symbol slot. The number of dual effective carriers is 48, which is the same for downlink and uplink PUSCs. Seventh, the structure of the downlink PUSC is composed of 28 carriers and two symbols. The number of valid carriers is 48, 24 each. The structure of an uplink PUSC consists of 24 carriers and 3 symbols. The number of valid carriers is 12 for the first and third symbols, and 24 for the second symbol, a total of 48.

On the other hand, the OFDMA TDD frame structure used in 3G-LTE has the following configuration. First, a CP exists for each physical resource block (PRB) and resource unit (RU). Second, the radio frame period of 3G-LTE is 10 ms. The radio frame is divided into two 5 ms radio sub-frames. The radio subframe is divided into 10 subframes, and each subframe has a period of 0.5 ms. Third, ten subframes are composed of PRBs and RUs, and may have ratios of 1: 4, 2: 3, 3: 2, and 4: 1. A single PRB can have seven symbols using the Short Cyclic Prefix (SCP) and six symbols when using the Long Cyclic Prefix (LCP). In contrast, a single RU uses six symbols. Fourth, the number of carriers in both PRB and RU is 25, and 8 of the total subcarriers are used for the reference symbol. The frequency spacing per carrier is 15 kHz. Fifth, if the PRB uses SCP, it can have a total of 175 subcarriers. Since eight subcarriers are used as the double reference symbol, the number of valid carriers is 167. On the other hand, when the PRB uses the LCP, it may have 150 subcarriers per PRB, and the number of valid subcarriers is 142 except for the reference symbol.

However, in case of MN's vertical handover from 3G-LTE network to WiMAX network (or WiMAX network to 3G-LTE network), in order to maintain QoS provided in existing network in target network, PHY layer And specs in the MAC layer should support this. Therefore, when receiving a handover request from a serving network, a base station and an access router of a target network need an appropriate resource reservation method to maintain the service level that the MN was currently providing. Do. In addition, there is a need for a QoS negotiation method for determining an appropriate QoS level when the QoS level of the MN is not maintained.

However, the existing 3G-LTE network or WiMAX network does not present a specific method for radio resource reservation and does not consider the QoS negotiation method to be performed during vertical handover.

Disclosure of Invention The present invention has been made to solve the above-described problem, and a heterogeneous network interworking system and a method for performing QoS negotiation and radio resource reservation between heterogeneous networks prior to handover, and a record recording a program for implementing the method. The purpose is to provide the medium.

The present invention has been made to achieve the above object, in the handover support method between heterogeneous networks, (a) for matching the NDR (Net Data Rate) of the serving network and the target network (target network) Performing a QoS negotiation; And (b) performing a radio resource reservation to support seamless handover between the heterogeneous networks by using radio resource parameters derived according to the QoS negotiation. It provides a handover support method between heterogeneous networks characterized in that.

Preferably, the QoS negotiation for NDR matching in step (a) is performed until the effective NDR of the target network from which the bit component corresponding to the overhead is removed is greater than or equal to the NDR of the serving network. It is repeatedly performed while changing the radio resource parameters.

Advantageously, step (a) comprises: (aa) receiving a NDR of the serving network or generating a virtual NDR having an NDR outlier value of the serving network; (ab) calculating an effective NDR in the target network using the received NDR or radio resource parameter used to calculate the virtual NDR; (ac) comparing the calculated effective NDR with the received NDR or the virtual NDR; And (ad) performing the step (b) if the calculated effective NDR is greater than or equal to the received NDR or the virtual NDR, and if the calculated valid NDR is less than the received NDR or the virtual NDR; And performing feedback after changing the radio resource parameter.

In another aspect, the present invention provides a handover method between heterogeneous networks, the method comprising: (a) establishing a communication channel between a user terminal to which a user connects through a serving network and a counterpart terminal corresponding thereto; (b) when the user terminal or the counterpart terminal enters a target network area, performs QoS negotiation for NDR (Net Data Rate) matching between the serving network and the target network, and performs the QoS negotiation. Performing radio resource reservation to support seamless handover between the heterogeneous networks using radio resource parameters derived accordingly; (c) in addition to step (b), an IP network performing bi-casting on the serving network and the target network; And (d) when both step (b) and step (c) are completed, establishing a communication channel between the user terminal and the counterpart terminal through the target network. Provide an over method.

Advantageously, step (b) comprises the step of the target network calculating and predicting a handover timing using radio resource parameters derived according to the QoS negotiation.

In addition, the present invention is a heterogeneous network interworking system including two networks having a different communication method, comprising: a serving network provided to form a communication channel with another terminal before a specific terminal moves to another network; And when the specific terminal reaches or leaves the boundary of the serving network, performs QoS negotiation for NDR (Net Data Rate) matching with the serving network, and a radio resource parameter derived according to the QoS negotiation. ) To perform a radio resource reservation to support seamless handover between heterogeneous networks, and to provide a handover to the specific terminal and the other terminal. It provides a heterogeneous network interworking system.

Preferably, the heterogeneous network interworking system further includes an IP network storing data packets of the counterpart terminal and performing bi-casting on the serving network and the target network.

The present invention produces the following effects in accordance with the configuration and method described below. First, seamless handover can be realized in heterogeneous networks (eg, 3G-LTE networks and WiMAX networks). Second, accurate mathematical modeling is possible by analyzing each network in units of Automatic Repeated ReQuest (ARQ) and Protocol Data Unit (PDU) using parameters of the PHY and MAC layers.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. First of all, in adding reference numerals to the components of each drawing, it should be noted that the same reference numerals are used as much as possible even if displayed on different drawings. In addition, in describing the present invention, when it is determined that the detailed description of the related known configuration or function may obscure the gist of the present invention, the detailed description thereof will be omitted. In addition, the following will describe a preferred embodiment of the present invention, but the technical idea of the present invention is not limited thereto and may be variously modified and modified by those skilled in the art.

1 is a conceptual diagram of a heterogeneous network interworking system according to a preferred embodiment of the present invention. As shown in FIG. 1, the heterogeneous network interworking system 100 according to a preferred embodiment of the present invention interoperates a Third Generation-Long Term Evolution (3G-LTE) network and a worldwide interoperability for microwave access (WiMAX) network. A system for a user terminal (MN) 110, a 3G-LTE network 120, a WiMAX network 130, an Operators IP Service (140) and a Correspondence Node (CN) ( 150).

The heterogeneous network interworking system 100 according to the present invention is a system for interworking the 3G-LTE network 120 and the WiMAX network 130, but the network to be interworked is not necessarily limited thereto. The network capable of interworking with the heterogeneous network interworking system 100 may be a network having different communication methods. For example, 3GPP UMB (The 3rd Generation Partnership Project Ultra Mobile Broadband) or UMTS (Universal Mobile Telecommunications System) are possible.

The heterogeneous network interworking system 100 according to the present invention serves to create a condition for handover between the user terminal 110 and the counterpart terminal 150 smoothly. The handover at this time is a seamless handover, and is characterized in that it is a vertical handover.

The heterogeneous network interworking system 100 according to the present invention provides orthogonal frequency division multiplexing (OFDM) and multiple input multiple output (MIMO). In addition, the heterogeneous network interworking system 100 may apply an adjacent cell interference cancellation technique to prevent the QoS degradation when crossing the boundary of the base station. In addition, the heterogeneous network interworking system 100 applies a multi-hop reception algorithm that seeks signal stability through software defined radio (SDR), low density parity check (LDPC), smart antenna, and relay station (RS). It is possible.

The user terminal 110 is a terminal to which a service user connects, and in the present invention, refers to a caller-side mobile device. On the other hand, the counterpart terminal 150 is a terminal to which the counterpart of the service user is connected. In the present invention, the counterpart terminal refers to the receiver-side mobile device. The user terminal 110 and the counterpart terminal 150 is characterized in that the mobile terminal is guaranteed mobility in the embodiment of the present invention. Meanwhile, the counterpart terminal 150 may be a counterpart of the user terminal 110 and may be implemented as a general server for processing a request of the user terminal 110.

In the embodiment of the present invention, the 3G-LTE network 120 may include a first base station (BS1) 121, a home subscriber system (HSS) server 122, a mobility management entity (MME) device 123, and a serving gateway (S). Serving GateWay (GW) 124 and Process (Packet) Data Network (PDN) gateway 125.

The HSS server 122 is a server functioning as a home agent (HA), and includes a database that stores profile information of the terminals 110 and 150 in a standby, incoming or outgoing state. The HSS server 122 is developed from the home location register (HLR) in the conventional mobile communication system, and performs functions such as user registration / change management, authentication, authorization, location, session routing, and billing. On the other hand, the database stores the identification number (MIN; Mobile Identification Number), unique number (ESN: Electronic Serial Number) of the terminal (110, 150), information about the type of mobile communication services subscribed.

The MME device 123 may include a parameter extracting unit extracting a PHY parameter and a MAC parameter, a GDR calculating unit calculating a GDR (Gross Data Rate), an NDR calculating unit calculating a Net Data Rate (NDR), A bandwidth calculation unit for calculating a bandwidth, an ARQ block size measurement unit for measuring an Automatic Repeat reQuest (ARQ) block size, an effective NDR calculation unit for calculating an effective NDR, and a calculated effective NDR It includes an NDR comparison unit for determining whether the NDR is abnormal, a radio resource reservation unit for performing radio resource reservation, an iteration execution unit for performing an iteration, a communication unit, a control unit, and the like. . A function performed by each component of the MME device 123 will be described later in detail with reference to FIG. 3, which will be omitted. Meanwhile, the MME device 123 may also be implemented as a user plane entity (UPE) in an embodiment of the present invention.

The serving gateway 124 and the PDN gateway 125 serve as a gateway. In the embodiment of the present invention, the serving gateway 124 is connected to the first base station 121, and the PDN gateway 125 is It is connected with the IP service network 140.

Meanwhile, in the present invention, the 3G-LTE network 120 is described for convenience. However, this is a 3G-LTE / SAE (System Architecture Evolution) in consideration of indicating the next generation high performance mobile broadband network based on 3GPP (The 3rd Generation Partnership Project) Release 8 Can be understood as a standard.

The WiMAX network 130 may include a second base station (BS2) 131, an access service network (ASN) gateway 132, a connectivity service network (CSN) device 133, and a home-aaa (H-AAA) in an embodiment of the present invention. Authentication Authorization Accounting) server 134 and CSN device 133 having a CSN (133). The WiMAX network 130 follows IEEE 802.16e (ie, mobile WiMAX) to which mobility is granted in an embodiment of the present invention. However, the WiMAX network 130 may also apply IEEE 802.16-2004 (ie, fixed WiMAX).

The H-AAA server 134 is a server having an HA function with the HSS server 122. Specifically, the H-AAA server 134 performs subscriber authentication, authority verification, and charging. Regarding the H-AAA server 134, for example, PCT International Application Publication No. 2004-80096 (name of the invention: User plane-based location services system, method and apparatus), and the detailed description thereof will be omitted below. do.

In an embodiment of the present invention, the CSN device 133 may include a parameter extractor, a GDR calculator, an NDR calculator, a bandwidth calculator, an ARQ block size measurer, a PDU size measurer that measures a size of a protocol data unit (PDU), And an ARQ block computing unit, an effective NDR calculating unit, an NDR comparing unit, a radio resource reservation unit, an iteration execution unit, a communication unit, a control unit, etc. for calculating the number of ARQ blocks. A function performed by each component of the CSN device 133 will be described later in detail with reference to FIG. 4, which will be omitted.

The ASN gateway 132 and the CSN 135 serve as a gateway. In the embodiment of the present invention, the ASN gateway 132 is connected to the second base station 131, and the CSN 135 is the IP service network 140. ).

Meanwhile, in the exemplary embodiment of the present invention, the 3G-LTE network 120 and the WiMAX network 130 respectively constitute separate base stations and networks, but are not necessarily limited thereto. That is, the 3G-LTE network 120 and the WiMAX network 130 may share one base station.

IP service network 140 refers to a conventional IP network (ie, an IP network), and may be implemented as a packet switching network in an embodiment of the present invention. Preferably, IP service network 140 is implemented with an Internet Protocol Multimedia Sub-system (IMS) or Packet Switch Stream (PSS).

Next, a handover support method between the 3G-LTE network 120 and the WiMAX network 130 according to a preferred embodiment of the present invention will be described. First, the handover support method from the 3G-LTE network 120 to the WiMAX network 130 will be described, and the handover support method from the WiMAX network 130 to the 3G-LTE network 120 will be described next. 3 is a flowchart illustrating a method for supporting handover from a 3G-LTE network to a WiMAX network according to a preferred embodiment of the present invention.

Referring to FIG. 3, a Quality of Service negotiation is first performed for seamless handover from the 3G-LTE network 120 to the WiMAX network 130. The QoS negotiation is for matching a Net Data Rate (NDR) between two networks 120 and 130. Here, the WiMAX network 130 provides the QoS provided by the 3G-LTE network 120 to the user terminal 110. Is deployed as a process of securing. Specifically, the CSN device 133 of the WiMAX network 130 performs the following functions for QoS negotiation.

First, the CSN device 133 refers to the NDR in the WiMAX network 130 with reference to a stored table to align the NDR (Net Data Rate) in the 3G-LTE network 120. In the embodiment of the present invention, the assumed NDR will be referred to as a virtual NDR. Specifically, the NDR is performed according to the following procedure. On the other hand, the above-mentioned NDR value is also described in PCT International Application Publication No. 2005-101731 (name of the invention: Wireless communication protocol), detailed description thereof will be omitted.

The first parameter extractor extracts PHY parameters in the physical layer or MAC parameters in the datalink layer (S300). In this case, the parameters extracted by the first parameter extractor include the number of slots, the number of symbols belonging to each slot, the number of effective sub-carriers belonging to each symbol, and each symbol. Number of bits, a code rate, a time division duplex (TDD) frame period, and the like. In addition, the first parameter extractor may additionally extract a bandwidth that can be maximized, a protocol data unit (PDU) size, the number of slots in the PDU, and the like. The parameter in the physical layer and the parameter in the data link layer are characterized in that the radio resource parameter (radio resource parameter) to be reserved as a radio resource in the embodiment of the present invention, which will be briefly referred to as a parameter in the following description.

Next, the first GDR calculator calculates a GDR (Gross Data Rate) value supported by the WiMAX network 130 (S305). Calculation of the GDR value of the first GDR calculation unit is specifically performed according to the following procedure. In a first step, the first GDR calculator calculates the total number of bits of a single TDD frame using the data extracted by the first parameter extractor. In this case, the data used by the first GDR calculator includes the number of slots belonging to a TDD frame, the number of symbols belonging to a single slot, the number of valid subcarriers belonging to a single symbol, and the like. If the first GDR calculator fails to secure these data prior to the execution of the first step, the data calculation process may proceed. In the second step, the first GDR calculator calculates a GDR value by dividing the total number of bits of a single TDD frame by a TDD frame period.

Next, the first NDR operator calculates a virtual NDR by reflecting a code rate on the previously calculated GDR value (S310). The virtual NDR in the WiMAX network 130 is a value set to be higher than the NDR in the 3G-LTE network 120 and can be embodied through Equation 1 below. Each element shown in [Equation 1] and its definition are described in FIG. 2A, and detailed description thereof is omitted here.

When the virtual NDR is calculated through steps S300 to S310, the CSN device 133 then calculates the actual NDR in the WiMAX network 130. The specific procedure is as follows.

First, the first bandwidth calculator calculates a bandwidth in consideration of a sub-channelization method corresponding to a system environment in the WiMAX network 130 (S315). Sub-channelization methods include a partial usage sub-channel (PUSC) and a full usage sub-channel (FUSC). Accordingly, the first bandwidth calculation unit calculates the number of sub-channels in each bandwidth and each sub-channel. The number of carriers belonging to each other, frequency spacing between carriers, and the like are used. Step S315 may be embodied through Equation 2 below, and each element shown in Equation 2 and its definition may be referred to FIG. 2A. Hereinafter, each element shown in [Equation 3] to [Equation 8] described below and its definition will of course refer to FIG. 2A.

Next, the first ARQ block size measuring unit measures the size of an Automatic Repeat reQuest (ARQ) block according to a system condition required by the WiMAX network 130 (S320). In detail, it is as shown in [Equation 3].

Here, the range of b value is 1-7.

Next, the first PDU size measurement unit calculates the number of PDUs in the iteration j-th attempt and the number of slots included in each PDU, and measures the size of the PDUs based on this (S325). If you specify the step S325 is shown in Equation 4.

Next, the first ARQ block number calculator is encapsulated in a specific PDU at an iteration j th attempt (where j is an arbitrary integer value) based on the parameters provided and the measured size of the ARQ block. The number of ARQ blocks is calculated (S330). The embodiment of the S330 step is as shown in [Equation 5].

In the above, i is the number of slots included in a specific PDU.

Next, the first effective NDR calculator calculates an effective NDR in the WiMAX network 130 at the j-th iteration (S335). The specific procedure is as follows. In a first step, the first valid NDR calculator calculates the lengths of the tail bits component and the cyclic redundancy check bits. Thereafter, in the second step, the first effective NDR calculator calculates an effective NDR by using the values extracted, measured, and calculated by the components 300 to 330 described above. This effective NDR corresponds to the actual NDR in the WiMAX network 130, and is specifically calculated using Equation 6.

In the above description, the effective NDR value calculated by the first valid NDR calculator is calculated by deducting a tail bit component and a CRC bit component corresponding to an overhead from a media access control (MAC) PDU. Only components that are valid for the value will be present. In addition, in the embodiment of the present invention, it is preferable that the effective NDR also considers a channel quality indicator (CQI) value of the second base station 131.

Next, the first NDR comparison unit compares the effective NDR to determine whether the effective NDR has a value equal to or greater than the virtual NDR calculated by the first NDR calculator (S340). If the effective NDR is greater than or equal to the virtual NDR, the first radio resource reservation unit performs radio resource reservation using the parameters extracted by the first parameter extraction unit (S345). In the embodiment of the present invention, the radio resource reservation is for supporting seamless handover between two networks 120 and 130, and is identical to the communication channel environment provided by the 3G-LTE network 120 to the user terminal 110. In order to create an environment in the WiMAX network 130, a method of reserving a parameter meeting a condition is referred. Meanwhile, the resource reserved in step S345 includes the number of slots in the iteration jth attempt, the number of valid subcarriers belonging to a single symbol, the number of symbols belonging to a single slot, and the number of bits in each symbol in the iteration jth attempt. , Code rate on the j-th iteration, and so on.

On the other hand, if the effective NDR is smaller than the virtual NDR, the first iteration execution unit additionally executes the iteration in cooperation with the second base station 131 or the ASN gateway 132 (S350). In the present invention, two methods are proposed to execute the step S350, which refers to an incremental number of slots (INS) method and an adaptive modulation and coding (AMC) method for increasing the number of slots in a TDD frame period.

According to the electronic method, the number of PDUs, the number of slots included in each PDU, the size of the PDUs, etc. are changed, and the details are shown in Equation 7 below.

In the above, M is an integer value.

When the step S350 is performed according to the electronic method, the first control unit then returns to step S325, and steps S325 to S340 are executed.

Meanwhile, according to the latter method, the modulation scheme and code rate in the WiMAX network 130 are changed. The details are shown in Equation 8 below.

When the step S350 proceeds according to the latter method, it is then fed back to the step S305 by the first controller, and steps S305 to S340 are executed.

As described above, the serving network is a 3G-LTE network 120 and the target network is a WiMAX network 130. However, the system according to the present invention (ie, the system in FIG. 1) may support handover even when the serving network is the WiMAX network 130 and the target network is the 3G-LTE network 120. The following description is for this. 4 is a flowchart illustrating a method for supporting handover from a WiMAX network to a 3G-LTE network according to an exemplary embodiment of the present invention.

Referring to FIG. 4, the method for supporting handover from the WiMAX network 130 to the 3G-LTE network 120 is generally the same as the method of FIG. 3, which will be described below. First, QoS negotiation is performed between the WiMAX network 130 and the 3G-LTE network 120 to match the NDR. The specific procedure of this process is as follows.

The second parameter extractor of the MME device 123 extracts the PHY parameter or the MAC parameter (S400). In an embodiment of the present invention, the PHY parameter and the MAC parameter are values stored in a table, but are not necessarily limited thereto. For example, the PHY parameter and the MAC parameter may be provided from a partner network (here, the 3G-LTE network).

The parameters extracted by the second parameter extractor may include the number of channels, the number of physical resource blocks (PRBs) required for a single channel, the number of valid carriers belonging to a single PRB, and a single symbol at the iteration j th attempt. The number of bits to be configured, the coding rate at the jth iteration of the iteration, and the like. In addition to this, the second parameter extractor may additionally extract the maximum expandable bandwidth, the size of the ARQ block, and the like. Meanwhile, in an embodiment of the present invention, the second parameter extractor may extract a resource unit (RU) instead of a PRB in a channel.

Next, the second GDR calculator calculates a GDR supported by the 3G-LTE network 120 (S405). Then, the second NDR operator calculates the virtual NDR in the 3G-LTE network 120 by reflecting the coding rate to this value (S410). The NDR calculation can be embodied as shown in Equation 9 below, and each element shown in Equation 9 and its definition refer to FIG. 2B. Of course, the following equation is also referred to Figure 2b.

The actual NDR calculation of the MME device 123 then follows.

First, the second bandwidth calculator calculates a bandwidth by using the number of PRBs belonging to a single channel, the number of carriers assigned to a single PRB, and the frequency interval between carriers (S415). The bandwidth calculation can be specified as shown in [Equation 10].

Next, the second ARQ block size measurement unit measures the size of the ARQ block according to the system state required by the 3G-LTE network 120 (S420). Since the size of the ARQ block measured in step S420 is determined according to the size of the PRB, it may be calculated by multiplying the number of valid subcarriers belonging to a single PRB by the number of bits of a single symbol in the iteration jth attempt. The size of the ARQ block is measured according to [Equation 11].

Next, the second effective NDR calculator calculates an effective NDR in the 3G-LTE network 120 at the ith j-th attempt (S425). The effective NDR calculation can be specified as shown in [Equation 12].

Next, the second NDR comparison unit compares these to determine whether the effective NDR is a value greater than or equal to the virtual NDR (S430). If the effective NDR is greater than or equal to the virtual NDR, the second radio resource reservation unit performs radio resource reservation using the parameters extracted by the parameter extractor (S435). In this case, the reserved radio resources include the number of channels, the number of PRBs per channel, the number of valid subcarriers belonging to the PRB, the number of bits of symbols in the iteration jth attempt, the coding rate in the iteration jth attempt, Total number of PRBs in a TDD frame period.

On the other hand, if the effective NDR is smaller than the virtual NDR, the second iteration execution unit additionally executes the iteration in association with the first base station 121 or the serving gateway 124 (S440). As in the case of FIG. 3, there are two methods proposed to execute step S440. One is the Increment the Size of PRB (ISPR) method for increasing the number of PRBs per single channel of the TDD frame period, and the other is the AMC method. to be.

According to the electronic method, the number of PRBs per single channel and the total number of PRBs in a TDD frame period are changed, and the details thereof are shown in Equation 13 below.

When the step S440 is performed according to the electronic method, it is then fed back to the step S415 by the second controller, and steps S415 to S430 are executed.

On the other hand, according to the latter method, the modulation scheme and coding rate in the 3G-LTE network 120 is changed, the details thereof are as shown in [Equation 14].

When the step S440 is performed according to the latter method, it is then fed back to the step S405 by the second controller, and steps S405 to S430 are executed.

Next, a seamless handover method performed in a vertical handover environment between the 3G-LTE network 120 and the WiMAX network 130 will be described. The seamless handover method to be described below is a handover method performed when the user terminal 110 enters a target network from a serving network in a heterogeneous network interworking system 100. In this case, the serving network may be set as the 3G-LTE network 120 or the WiMAX network 130, and the target network may be set as a network having a different communication method from the serving network.

5 is a flowchart illustrating a seamless handover method of a heterogeneous network interworking system according to a preferred embodiment of the present invention. The seamless handover method to be described with reference to FIG. 5 is characterized by considering the handover support method described above with reference to FIGS. 3 and 4. In addition, the seamless handover method in FIG. 5 assumes that the serving network is the WiMAX network 130 and the target network is the 3G-LTE network 120.

Referring to FIG. 5, the user terminal 110 and the counterpart terminal 150 access the WiMAX network 130 to form a communication channel (S500). Then, the user terminal 110 receives the data packet generated at the counterpart terminal 150 via the H-AAA server 134 which is an HA.

When the user terminal 110 moves from the WiMAX network 130 to the 3G-LTE network 120, the 3G-LTE network 120 starts to prepare for the handover execution (S505). In this case, the 3G-LTE network 120 may perform soft handover, but may also execute hard handover. Meanwhile, in step S505, the 3G-LTE network 120 needs a process of checking an interworking target network, which is a process of checking a neighbor cell state and a radio access station (RAS) ID in a neighbor advertisement message. It can be omitted because it can be recognized.

After operation S505, the 3G-LTE network 120 interworkes with the WiMAX network 130 to execute QoS negotiation, radio resource reservation, etc. for handover support (S510). Step S510 is described in detail with reference to FIGS. 3 and 4.

However, since the 3G-LTE network 120 executes the soft handover, the connection between the user terminal 110 and the counterpart terminal 150 should be maintained even while step S510 is executed. To this end, the heterogeneous network interworking system 100 according to the present invention executes bi-casting (S515). Step S515 continues until the end of step S510, specifically proceeds as follows. Preferably, step S515 is simultaneously performed and completed simultaneously with step S510.

In the first step, the IP service network 140 receives and stores the data packet generated by the counterpart terminal 150. This is in consideration of the LPM (Last Packet Marker) method, and is for seamless handover. In a second step, IP service network 140 connects to PDN gateway 125 of 3G-LTE network 120 and transmits a data packet. In this case, the IP service network 140 may access the CSN 135 and transmit a data packet. In a third step, the PDN gateway 125 transmits the data packet to the first base station 121 through the serving gateway 124. In addition, the PDN gateway 125 accesses the ASN gateway 132 of the WiMAX network 130 and transmits a data packet. Then, the ASN gateway 132 transmits the data packet to the second base station 131.

Through the above first to third steps, the user terminal 110 can receive a data packet from the first base station 121 or the second base station 131, and can implement seamless handover.

Meanwhile, in step S510, the 3G-LTE network 120 may calculate and predict handover timing by using the calculated parameter value. When the 3G-LTE network 120 predicts the handover timing, it is possible to optimize the bicasting and eliminate the loss of data packets.

When step S510 ends, step S515 ends, and then the user terminal 110 forms a communication channel with the counterpart terminal 150 through the 3G-LTE network 120 (S520). Meanwhile, in an embodiment of the present invention, the heterogeneous network interworking system 100 may consider a PSS (Portable Subscriber Station) movement prediction algorithm to easily grasp the movement of the user terminal 110.

Next, for example, the QoS negotiation and radio resource reservation process required for handover from the 3G-LTE network 120 to the WiMAX network 130 are calculated according to the actual PHY parameter value and the MAC parameter value.

경우 when the effective NDR is smaller than the virtual NDR in step S340 of FIG. 3

NDR in serving network: 1 Mbps

Modulation scheme: 64QAM: b _w ^(j) = 6 bits

Code rate:

ARQ Block Size: 16bytes = 128bits

DL-FUSC: C _W = 48, S _W = 1

CRC _W ^(j) = 16 bits, TR _W = 0 bits

BW _W = N _{sub _W} * C _OW * f _W = 2 * 54 * 9.765625 = 1.0546875MHz

b = 1 so A _W = 2 ^{b + 6} = 2 ⁷ = 128bits

N ₍₁₎ ^(j) = 21, N ₍₂₎ ^(j) = 3, m = 2

N _P ^(j) = 21 + 3 = 24

From above R _NT ^(j) = 0.8448 Mbps

therefore,

According to the result, the target network does not guarantee the effective NDR provided by the serving network to the user terminal 110, and thus performs the above recursive process through the following two processes.

First course:

Slot-> N _W ^{(j + 1)} = N _W ^(j) + M (where M is an integer)

(i) R _NT ^{(j + 1)} = 0.952533 Mbps (M = 1) Therefore, R _NT ^{(j + 1)} <R _NS

(ii) R _NT ^{(j + 2)} = 0.986666 Mbps (M = 2) Thus, R _NT ^{(j + 2)} <R _NS

(iii) R _NT ^{(j + 3)} = 1.0208 Mbps (M = 3) Thus, R _NT ^{(j + 31)} > R _NS

The first process is a method of measuring and comparing effective NDRs by gradually increasing the number of slots in a TDD frame and recursively increasing the number of slots so that the target network guarantees the NDRs provided by the serving network to the user terminal 110. Procedures are carried out. In the above process, the iteration j + 1 is performed to increase the number of slots from the existing 27 to 28 (M = 1). In this step, the serving network is still provided to the user terminal 110 by the serving network. It can be seen that less than the NDR. Therefore, after performing the next step, iteration j + 2, the number of slots was increased to 29 (M = 2) and the NDR operation process was performed. It can be seen that less than the NDR provided to the terminal 110. Next, in the iteration j + 3 process of increasing the number of slots to 30 (M = 3), it can be seen that the target network is finally larger than the NDR provided by the serving network to the user terminal 110. Through this process, the target network enters into a substantial handover timing prediction option by providing a system base that minimizes the NDR provided by the serving network to the user terminal 110.

Second Step: Adaptive Modulation and Coding Rate (AMC)

Modulation Scheme: b _W ^{(j + 1)} = b _W ^(j)

Code rate: K _W ^{(j + 1)} = 4/5

R _NT ^{(j + 1)} = 1.1027 Mbps, therefore R _NT ^{(j + 1)} > R _NS

The second process is a method of measuring and comparing NDRs using AMC that adjusts modulation or code rate appropriately for a channel environment and changes the modulation so that the target network guarantees NDRs provided by the serving network to the user terminal 110. Thereby increasing the number of bits in the slot or adjusting the code rate. In the second process, since 64QAM (6 bits / symbol) is used in accordance with the specification of the WiMAX network (spec), a method of increasing the code rate based on the WiMAX specification is performed without further adding a bit. . The existing code rate was 2/3, increase it to 4/5, and then again obtain the NDR of the target network and compare it with the serving network. In the iteration j = 1 process, it can be seen that the target network is finally larger than the NDR provided by the serving network to the user terminal 110. Through this process, the target network enters the actual handover timing calculation prediction by providing a system base that minimizes the NDR provided by the serving network to the user terminal 110.

경우 If the effective NDR is larger than the virtual NDR in step S340 of Figure 3 does not perform step S350

NDR in serving network: 1 Mbps

Modulation Scheme: 64QAM: b _L ^(j) = 6bits

Code rate: K _L ^(j) = 2/3

Short Cyclic prefix used: C _L = 167

ARQ block size in WiMAX networks: P _L ^(j) = C _L * b _L ^(j) = 167 * 6 = 1002 bits

Channel condition: only 2 channel enabled

SDU _L ^(j) = 4800 bits

By the above

CH _L ^(j) = 2, CRC _L ^(j) = 24 bits, TR _L = 12 bits

BW _L = PRB _CH ^(j) * C _OL * f _L = 4 * 25 * 15 = 1500 kHz

Thus, R _NT ^(j) > R _NS

At this time, the target network enters into the realistic handover timing calculation prediction by ensuring the minimum effective NDR provided by the serving network to the user terminal 110. If the target network fails to guarantee the NDR provided by the serving network to the user terminal 110, the NDR provided by the target network to the user terminal 110 is at least as large as that of the first embodiment described above. Until the NDR or more provided to the terminal 110 is performed recursively.

Meanwhile, the above-described embodiments of the present invention can be written as a program that can be executed in a computer, and can be implemented in a general-purpose digital computer that operates the program using a computer-readable recording medium. The computer-readable recording medium may include a magnetic storage medium (for example, a ROM, a floppy disk, a hard disk, etc.), an optical reading medium (for example, a CD-ROM, a DVD, etc.) and a carrier wave (for example, Storage media such as transmission over the Internet).

The above description is merely illustrative of the technical spirit of the present invention, and those skilled in the art to which the present invention pertains various modifications, changes, and substitutions without departing from the essential characteristics of the present invention. will be. Accordingly, the embodiments disclosed in the present invention and the accompanying drawings are not intended to limit the technical spirit 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 the embodiments and the accompanying drawings. . The scope of protection of the present invention should be interpreted by the following claims, and all technical ideas within the scope equivalent thereto should be construed as being included in the scope of the present invention.

Currently, a network selection method or apparatus required for handover between two networks using the same communication method has been developed to some extent. However, the development of technologies, methods, and devices related to vertical handover is insignificant among heterogeneous networks using different communication methods (for example, an internet data based communication network and a cellular voice based communication network). Therefore, if the present invention implements various hierarchical approaches such as physical layer, data link layer, and IP layer, and executes QoS negotiation and radio resource reservation prior to handover, seamless handover between heterogeneous networks is possible. The market value is expected to be very high. In addition, the present invention can affect a wide range of mobile communication networks, mobile communication base stations, mobile communication terminals, etc., the market value is expected to further double.

1 is a conceptual diagram of a heterogeneous network interworking system according to a preferred embodiment of the present invention;

2A and 2B are tables defining parameters in two networks supporting handover according to a preferred embodiment of the present invention.

3 is a flowchart illustrating a handover support method from a 3G-LTE network to a WiMAX network according to a preferred embodiment of the present invention;

4 is a flowchart illustrating a method for supporting handover from a WiMAX network to a 3G-LTE network according to an embodiment of the present invention;

5 is a flowchart illustrating a seamless handover method of a heterogeneous network interworking system according to a preferred embodiment of the present invention.

<Description of Symbols for Main Parts of Drawings>

100: heterogeneous network interworking system 110: user terminal

120: 3G-LTE network 121: the first base station

122: HSS server 123: MME device

124: Serving Gateway 125: PDN Gateway

130: WiMAX network 131: second base station

132: ASN gateway 133: CSN device

134: H-AAA server 135: CSN

140: IP service network 150: counterpart terminal

Claims (21)

In the handover support method between heterogeneous networks, (a) performing QoS negotiation for Net Data Rate (NDR) matching between a serving network and a target network; And (b) performing radio resource reservation to support seamless handover between the heterogeneous networks by using radio resource parameters derived according to the QoS negotiation; Handover support method between heterogeneous networks comprising a. The method of claim 1, QoS negotiation for NDR matching in step (a) is set such that an effective NDR of the target network from which the bit component corresponding to the overhead is removed is equal to or greater than the NDR of the serving network or the NDR of the serving network. The handover support method between heterogeneous networks, wherein the radio resource parameters are repeatedly performed until they are greater than or equal to a virtual NDR. The method of claim 1, In step (a), (aa) receiving a NDR of the serving network or generating a virtual NDR having an NDR higher value of the serving network; (ab) calculating an effective NDR in the target network using a radio resource parameter used to calculate the received NDR or the virtual NDR; (ac) comparing the calculated effective NDR with the received NDR or the virtual NDR; And (ad) performing the step (b) if the calculated effective NDR is greater than or equal to the received NDR or the virtual NDR, and if the calculated valid NDR is less than the received NDR or the virtual NDR, the wireless Feedback after performing an iteration to change resource parameters Handover support method between heterogeneous networks comprising a. The method of claim 3, wherein The (aa) step, (aaa) extracting a parameter in a physical layer or a parameter in a data link layer as the radio resource parameter; (aab) calculating a cross data rate (GDR) using the extracted radio resource parameter; And (aac) calculating the virtual NDR using the calculated GDR Handover support method between heterogeneous networks, characterized in that for generating the virtual NDR using. The method of claim 3, wherein The virtual NDR in step (aa) uses Equation 1 below when the target network is a WiMAX network and Equation 2 below when the target network is a 3G-LTE network. How to support handover between heterogeneous networks. [Equation 1]

In the above _description , R _NW ^(j) is an NDR in a WiMAX network, R _GW ^(j) is a GDR (Gross Data Rate) in a WiMAX network, and K _W ^(j) is an iteration a certain number of times in a WiMAX network. Code rate, N _W ^(j) is the number of slots when iteration is performed a certain number of times in the WiMAX network, and C _W is the effective sub-carrier belonging to a single symbol in the WiMAX network. ), S _W is the number of symbols belonging to a single slot in the WiMAX network, b _W ^(j) is the number of bits in each symbol when iteration is performed a certain number of times in the WiMAX network, and T _W is the WiMAX network. Division Time Division Duplex (TDD) frame period [Equation 2]

In the above, R _NL ^(j) is the NDR in the 3G-LTE network, R _GL ^(j) is the GDR in the 3G-LTE network, K _L ^(j) is the number of times to perform iteration in the 3G-LTE network. If the code rate, CH _L ^(j) is the number of channels in the 3G-LTE network, PRB _CH ^(j) is the number of physical resource blocks (PRB) per channel in the 3G-LTE network, C _L is the PRB in the 3G-LTE network Or the number of valid subcarriers per resource unit (RU), b _L ^(j) is the number of bits of symbols when iteration is performed a certain number of times in the 3G-LTE network, and T _L is the TDD frame period in the 3G-LTE network. The method of claim 3, wherein (Ab) step, (aba) calculating a bandwidth that can be maximized in the target network; (abb) measuring a size of an ARQ block in consideration of a system state of the target network; And (abc) calculating the effective NDR obtained by subtracting a tail bit component and a CRC bit component using the radio resource parameter Handover support method between heterogeneous networks comprising a. The method of claim 3, wherein In the step (ab), the effective NDR calculation may be performed using Equation 1 below when the target network is a WiMAX network and Equation 2 below when the target network is a 3G-LTE network. How to support handover between networks. [Equation 1]

In the above, R _NT ^(j) is the effective NDR in the WiMAX network,

Is the number of slots in the WiMAX network, N _{ARQ (i)} ^(j) is the number of Automatic Repeat reQuest (ARQ) blocks in the WiMAX network, A _W is the size of the ARQ block in the WiMAX network, and TR _W is the size of the WiMAX network. Length of the tail bits, K _W ^(j) is the code rate in the WiMAX network, CRC _W ^(j) is the length of the CRC bits (Cyclic Redundancy Check bits) in the WiMAX network, T _W is the time division duplexing (TDD) frame period in a WiMAX network [Equation 2]

In the above, R _NT ^(j) is the effective NDR (NDR) in the 3G-LTE network, N _L ^(j) is the number of Physical Resource Block (PRB) or Resource Units (RU ⁾ in the 3G-LTE network, C _L is the number of valid subcarriers per PRB or RU in the 3G-LTE network, b _L ^(j) is the number of bits of the symbol in the 3G-LTE network, TR _L is the tail bits in the 3G-LTE network ), K _L ^(j) is the code rate in the 3G-LTE network, CRC _L ^(j) is the length of the Cyclic Redundancy Check bits in the 3G-LTE network, and T _L is Time Division Duplexing (TDD) frame period in 3G-LTE networks. The method of claim 6, The intermediate step between the (abb) step and the (abc) step, (abba) measuring the size of the PDU using the number of PDUs (Protocol Data Units) extracted and the number of slots when iteration is performed a predetermined number of times; And (abbb) calculating the number of ARQ blocks concealed in a specific PDU using the radio resource parameter provided by the serving network and the measured size of the ARQ block Handover support method between heterogeneous networks comprising a. The method of claim 1, The radio resource parameter registered when performing the radio resource reservation in the step (b) may include the number of slots, the number of valid subcarriers belonging to a single symbol, and the number of symbols belonging to a single slot when iteration is performed a predetermined number of times. Number, the number of bits of each symbol when iteration is performed a certain number of times, and the number of first group or channels including the code rate when the iteration is performed a certain number of times, the number of physical resource blocks (PRB) per channel, The number of valid subcarriers belonging to the PRB, the number of bits of the symbol if iteration is performed for a certain number of times, the coding rate if iteration is performed for a certain number of times, and the PRB in a time division duplexing (TDD) frame period Handover support method between heterogeneous networks, characterized in that the second group including the total number of. The method of claim 3, wherein The iteration operation in the step (ad) includes the Increment the Number of Slots (INS) method for increasing the number of slots in a TDD frame period, and the Increment the Size of PRB for increasing the number of PRBs per single channel in a TDD frame period. A handover support between heterogeneous networks, and any one of an AMC (Adaptive Modulation and Coding) method of varying a modulation scheme and a code rate in the target network. Way. The method of claim 10, The INS method and the ISPRB method feed back to the step (ab) after the step (ad), and the AMC method feeds back to the step (aa) after the step (ad). How to apply. The method of claim 1, And the serving network is one of a 3G-LTE network and a WiMAX network, and the target network is the other. In the handover method between heterogeneous networks, (a) establishing a communication channel between a user terminal to which a user accesses through a serving network and a counterpart terminal corresponding thereto; (b) when the user terminal or the counterpart terminal enters a target network area, performs QoS negotiation for NDR (Net Data Rate) matching between the serving network and the target network, and performs the QoS negotiation. Performing radio resource reservation to support seamless handover between the heterogeneous networks using radio resource parameters derived accordingly; (c) in addition to step (b), an IP network performing bi-casting on the serving network and the target network; And (d) when both step (b) and step (c) are completed, establishing a communication channel between the user terminal and the counterpart terminal through the target network Handover method between heterogeneous networks comprising a. The method of claim 13, The serving network is any one of a 3G-LTE network and a WiMAX network, wherein the target network is the other handover method between heterogeneous networks. The method of claim 13, In step (c), (ca) the IP network transmitting a data packet of the counterpart terminal to at least one of a process data network (PDN) gateway of the 3G-LTE network and a connectivity service network (CSN) of the WiMAX network; (cb) when the IP network transmits the data packet only to the PDN gateway in step (ca), the PDN gateway provides the data packet to an access service network (ASN) gateway of the CSN or the WiMAX network; Providing the data packet to the PDN gateway or a serving gateway (S-GW) of the 3G-LTE network when the IP network transmits the data packet only to the CSN in step (ca); And (cc) the ASN gateway or the serving gateway receiving the data packet transmitting the data packet to the user terminal Handover method between heterogeneous networks comprising a. The method of claim 13, Step (b) includes the step of the target network to calculate and predict the handover timing using the radio resource parameters derived according to the QoS negotiation, handover between heterogeneous networks. In a heterogeneous network interworking system including two networks having different communication methods, A serving network provided to establish a communication channel with another terminal before the specific terminal moves to another network; And When the specific terminal reaches or leaves the boundary of the serving network, QoS negotiation for NDR (Net Data Rate) matching with the serving network is performed, and a radio resource parameter derived according to the QoS negotiation. A target network that performs radio resource reservation to support seamless handover between heterogeneous networks using the network and provides handover to the specific terminal and the other terminal. Heterogeneous network interworking system comprising a. The method of claim 17, An IP network storing data packets of the counterpart terminal and performing bi-casting on the serving network and the target network. Heterogeneous network interworking system further comprising a. The method of claim 17, And the serving network is one of a 3G-LTE network and a WiMAX network, and the target network is the other. The method of claim 17, The serving network or the target network, A parameter extraction unit for extracting a parameter in the physical layer or a parameter in the data link layer as a radio resource parameter; A GDR calculator configured to calculate a cross data rate (GDR) using the extracted radio resource parameter; An NDR calculator configured to calculate an NDR (Net Dara Rate) using the calculated GDR, and generate a virtual NDR from the calculated NDR; An effective NDR calculator configured to calculate an effective NDR from which a bit component corresponding to an overhead is removed using a radio resource parameter provided by a partner network or a radio resource parameter extracted by the parameter extractor; An NDR comparison unit comparing the calculated effective NDR with an NDR provided by the counterpart network or the virtual NDR; A radio resource reservation unit configured to perform radio resource reservation by using a radio resource parameter used for calculating the effective NDR when the calculated effective NDR is greater than or equal to the provided NDR or the virtual NDR; And An iteration execution unit that executes an iteration to change the radio resource parameter used in the effective NDR calculation if the calculated effective NDR is less than the provided NDR or the virtual NDR Heterogeneous network interworking system comprising a. In a computer-readable recording medium, A recording medium storing a program for implementing the method according to any one of claims 1 to 16.

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