KR100594947B1 - The method of seamless packet sequence control to support for mobility in mobile network - Google Patents

Abstract

1. TECHNICAL FIELD OF THE INVENTION

The present invention relates to a continuous packet sequence control method for mobility support in a wireless communication network.

2. The technical problem to be solved by the invention

The present invention is to increase the efficiency of the network by minimizing the time taken for handoff while reducing the overhead of the buffer and considering the mobility between the PDSN (Packet Data Serving Node) as well as the Radio Network (RN) in a wireless communication network. To provide endless packet sequence control method for mobility support.

3. Summary of Solution to Invention

According to an aspect of the present invention, there is provided a method of controlling a packet sequence for mobility support in a wireless communication network, wherein a PDSN (Packet Data Serving Node) uses a movement direction and a speed of a mobile station to generate radio networks (RNs) on an expected movement path of the mobile station. A multicast group configuration step of constructing a multicast group; An expected handoff time notification step, wherein the PDSN notifies each estimated handoff time to each multicast group member RN; Transmitting, by the PDSN, a packet to be transmitted to the mobile station to member RNs of a multicast group; A packet storing step in which the RN in which the mobile station is currently located transmits a packet to the mobile station, and the other multicast group member RNs store the packet after each estimated handoff time; A packet number informing step, in which the mobile (new) RN is informed of the number of the packet last received by the mobile station from the mobile station as the mobile station moves to an adjacent RN and an inter-RN handoff occurs; And a second packet transmission step of transmitting a packet after a last number among the packets in which the new RN is stored to the mobile station.

4. Important uses of the invention

The present invention is used in wireless communication networks and the like.

Mobility Support, Handoff, Seamless Packet Sequence Control, Macro Mobility, Micro Mobility, Up Stream, Down Stream

Description

The method of seamless packet sequence control to support for mobility in mobile network}             

1 is a configuration diagram of an embodiment of a wireless communication network to which the present invention is applied.

FIG. 2A is an exemplary diagram illustrating a process of loss and reordering of down stream data packets according to the prior art. FIG.

2B is an exemplary view illustrating a procedure for changing an order of an upstream packet according to the prior art.

3 is a flowchart illustrating a method for controlling a downstream packet sequence for mobility support when a handoff occurs between PDSNs according to the present invention.

4 is a flowchart illustrating a method of controlling an upstream packet sequence for mobility support when a handoff occurs between PDSNs according to the present invention.

5 is a flowchart illustrating a method of controlling a packet sequence for mobility support when an inter-RN handoff occurs in a PDSN according to the present invention.

* Explanation of symbols for the main parts of the drawings

101: mobile station 102: RNx

103: PDSN 104: Home Agent

The present invention relates to a method of continuously controlling a packet sequence for supporting mobility in a wireless communication network, and more particularly, when a handoff occurs in a next generation mobile communication network of a standard established by 3GPP2 (Third Generation Partnership Project 2) or the like. Support for mobility in a wireless communication network for continuous handoff to support mobility so that continuous service is provided without reordering or losing data received from a mobile station (MS) or a correspondent node (CN). It relates to a continuous packet sequence control method for the.
In the following embodiment, the PDSN and RN which newly manages the mobile station when the handoff occurs are referred to as "New PDSN" and "New RN", and the PDSN and RN which has been responsible for the mobile station before the handoff occurrence are referred to as "Old PDSN" and "Old RN". Will be called.

Currently, handoff occurs in the next generation mobile communication network of the standard established by 3GPP2, etc. between PDSNs (Packet Data Serving Nodes) or between RNs (Radio Networks) in one PDSN, and mobility is represented by macro mobility (PD mobility) between PDSNs. Macro mobility is divided into micro mobility between RN. When a mobile station receives data from another mobile station or CN through PDSN and RN, it provides location transparency when there is a movement of mobile stations between PDSNs or RNs. Continuous connection service, ie, continuous handoff must be provided.

To this end, the next-generation mobile communication network of 3GPP2, etc., provides mobility by applying Mobile IP (MIP), and handoff Aware Wireless Access Internet Infrastructure (HAWAII) and cellular IP (Cellular IP) to support micro mobility. ) Method and the like have been proposed. However, the above mentioned methods are not sufficient to provide a continuous handoff, such as delaying a handoff when the packet is lost or the order of the packets is changed. The above is described with reference to FIG. 2 as follows.

FIG. 2A illustrates an example of a loss and reordering process of a down stream data packet according to the prior art. FIG.

As shown in FIG. 2A, when handoff occurs from "0ld PDSN" 202 to "New PDSN" 204 while data is downstream, problems of reordering and loss of data packets may occur. Can be. Among the data packets 1, 2, 3, 4, and 5 sent from the home agent (HA), the mobile station receives packet 1, and the remaining 2, 3 data packets are 0ld PDSN (202). If the handoff occurs while the 4th and 5th data packets have not been sent yet, the home agent 203 transmits the remaining 4th and 5th data packets to the "New PDSN" 204. At this time, data packets 2 and 3, which have been transmitted to the " 0ld PDSN " 202, are not transmitted to the mobile station through the " Old RN " 201, resulting in packet loss.

2B is an exemplary view illustrating a procedure for changing an order of an upstream packet according to the prior art.

As shown in FIG. 2B, in the case of upstream, a data packet 1 is forwarded to the home agent 203 before a handoff occurs from “Old PDSN” 202 to “New PDSN” 204. When a handoff occurs in a state in which data packets 2 and 3 are transmitted to 0ld PDSN "202, data packets 4 and 5 are transmitted to" New PDSN "204 through" New RN "205. At this time, when the traffic conditions of the "0ld PDSN" 202 is congested, a case in which data packets 4 and 5 of the "New PDSN" 204 arrive at the home agent 203 before data packets 2 and 3 may occur. Can be.

In addition, when a handoff occurs while the mobile station receives data from the "Old RN" 201 and moves to the "New RN" 205, the "New RN" 201 starts from the data immediately following the data received from the "Old RN" 201. RN "205, but since" New RN "205 does not have that data," New RN "205 notifies" 0ld PDSN "202 that a handoff has occurred. The data packet is received from the " Old PDSN " 202 and transmitted to the mobile station. Thus, in this case, service interruption occurs. As a way to resolve this service interruption, the "New RN" 205 should store data in advance. However, since the mobile station does not know which RN to move to, all of the neighboring RNs must store data in advance so that endless handoff processing can be performed. However, this method can provide a continuous handoff process, but may cause a buffer overhead problem with regard to data storage.

Thus, many studies are being actively conducted, one of which is the Korean Patent Registration No. 301704, "Packet Handoff Control Method with No Packet Loss in a Wireless Data Mobile Communication Network," which is registered on June 27, 2001. The contents are briefly described as follows.

Prior arts prior to the prior patent have been developed in various countries for packet-switched wireless communication network for providing packet data services such as Internet access in the IMT-2000 network. Here, an alternative method for supporting third generation mobile packet data service is an "Overlay Network Service" type. When the mobile IP of the mobile IP moves to the area of another agent in the IMT-2000 network, Smooth handoff is proposed as a handoff scheme. However, smooth handoff of mobile IPs has some problems for use in mobile network environments such as IMT-2000. When handoff is implemented in the mobile network according to the smooth handoff control method of the mobile IP, the mobile station receiving a packet receives a care-of address (COA) from an agent in the newly entered area and informs the previous agent. All packets between them will be lost until the location change registration is made. The lost packet is then retransmitted by retransmission request of higher protocol. In addition, frequent retransmission requests in the mobile network cause the other host (or mobile station) to reduce the size of the transmission window to reduce the efficiency of the network even though no actual data congestion occurs. Thus, the prior patents have a plurality of COAs through two Point-to-Point Protocol (PPP) connections at the time of handoff to solve this problem, with no packet loss and guaranteed quality of service (QoS) We propose a handoff control method.

However, although the prior patent is a packet handoff control method without packet loss in a wireless data mobile communication network, only a macro mobility control method for packet handoff between PDSNs is presented. In addition, the prior patent does not minimize the time taken during handoff and the way to minimize the capacity of the buffer.

Therefore, there is a demand for a method capable of minimizing the capacity of the buffer and minimizing the handoff time in consideration of mobility between RNs as well as between PDSNs.

The present invention has been proposed to meet the above requirements, and considers the mobility between RN (Radio Network) as well as PDSN (Packet Data Serving Node) in a wireless communication network, while reducing the overhead of the buffer handoff It is an object of the present invention to provide a method of continuously controlling a packet sequence for supporting mobility to minimize network time and increase network efficiency.

In accordance with an aspect of the present invention, there is provided a method of controlling a packet sequence for mobility support in a wireless communication network, wherein a PDSN multicasts RNs on an expected movement path of the mobile station by using the movement direction and speed of the mobile station. Multicast group configuration step of organizing into groups; An expected handoff time notification step, wherein the PDSN notifies each estimated handoff time to each multicast group member RN; Transmitting, by the PDSN, a packet to be transmitted to the mobile station to member RNs of a multicast group; A packet storing step in which the RN in which the mobile station is currently located transmits a packet to the mobile station, and the other multicast group member RNs store the packet after each estimated handoff time; A packet number informing step, in which the mobile (new) RN is informed of the number of the packet last received by the mobile station from the mobile station as the mobile station moves to an adjacent RN and an inter-RN handoff occurs; And a second packet transmission step of transmitting a packet after a last number among the packets in which the new RN is stored to the mobile station.

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As described above, in the present invention, a mobile IP is used to support macro mobility of a next generation mobile communication network, and a PDSN performs a function of a foreign agent. In this case, the mobility supported when the mobile station moves from one PDSN to another PDSN is referred to as macro mobility, and the mobility supported when moving from one RN to another RN in the PDSN management area is referred to as micro mobility. It is called.

The present invention is a method to compensate for problems such as packet loss and packet order change that may occur in macro mobility, when handoff for each case of the down stream and the up stream of the packet. The present invention relates to a continuous handoff algorithm between PDSNs using packet sequence control.

The present invention also relates to a continuous handoff algorithm based on a multicast group construction mechanism for micro mobility support when the mobile station moves between RN and RN in PDSN.

The continuous handoff algorithm based on the multicast group mechanism calculates a moving direction and a speed of the mobile station, configures RNs adjacent to the mobile station's expected movement path into a multicast group, and delays the multicast group joining point as much as possible. Increase the efficiency of the network

In addition, in order to solve the problem of the buffer overhead of the existing multicast connection method, the PDSN transmits only data after the expected handoff time, and the RN also buffers only data after the expected handoff time.

The above objects, features and advantages will become more apparent from the following detailed description taken in conjunction with the accompanying drawings. Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a configuration diagram of an embodiment of a wireless communication network to which the present invention is applied.

As shown in FIG. 1, data from the home agent 104 to the mobile station 101 is transferred by the RNx 102 from the home agent 104 via the PDSN 103. Data from the mobile station 101 to the home agent 104 is also sent to the home agent 104 via the PDSN 103 via the RNx 102.

In FIG. 1, handoff occurs when the mobile station 101 moves between RNx 102 and RNx 102 or when moving between PDSN 103 and PDSN 103, where constant packet sequence control is required. Do.

3 is a flowchart illustrating a method of controlling a downstream packet sequence for mobility support when a handoff occurs between PDSNs according to the present invention.

Message names and buffer names used below are merely examples in applying the present invention.

Referring to FIG. 3, in the case of the downstream, when the handoff occurs, the packet sequence control process is performed. Before the handoff occurs, the "Old PDSN" stores the packets coming from the home agent in the "Down_Buffer" (301), and the "Old RN". "302". If a handoff occurs, the "New PDSN" delivers a "Handoff_Gen" message indicating the handoff occurrence to the "Old PDSN" (303). Then, the "Old PDSN" receives "Handoff_Gen" from the "New PDSN" and forwards this message back to the home agent (304), and delivers a "Handoff_Ack" message to the "New PDSN" informing of receiving a handoff occurrence message ( 305).

On the other hand, the home agent transmits the packet to the "Old PDSN" until it receives the "Handoff_Gen". After receiving the "Handoff_Gen" message, the home agent sends the "Handoff_DownEnd" message to the "Old PDSN" (306), and then transmits the next packet to the "New PDSN" (307), and the "New PDSN" is data from the home agent. Is stored in Down_Buffer.
The packet stored in "Down_Buffer", which is a buffer for storing data from the home agent, is transmitted to the "New PDSN" by the "Old PDSN" (308). Here, if "Old PDSN" transmits all packets in "Down_Buffer" to "New PDSN", "Old PDSN" transmits "Handoff_DownEnd" message to "New PDSN" (309) and is in an idle state. Becomes
Then, "New PDSN" stores the packet received from "Old PDSN" in "Ho_Buffer". Then, the "New PDSN" preferentially transmits the packet stored in the "Ho_Buffer" to the "New RN" (310).

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Also, after receiving "Handoff_DownEnd" message, "New PDSN" checks "Ho_Buffer" and if there is no packet to send, terminates handoff sequence control and sends the packet stored in "Down_Buffer" to "New RN" under normal data transmission. (311).

4 is a flowchart illustrating an upstream packet sequence control method for mobility support when a PDSN handoff occurs according to the present invention.

Referring to FIG. 4, a method of controlling a packet sequence when a handoff occurs in the upstream case is as follows. First, the "Old PDSN" stores the packet received from the "Old RN" in the "Up_Buffer" (401) and forwards it to the home agent (402).

If a handoff occurs, the "New PDSN" delivers a "Handoff_Gen" message to the "Old PDSN" (403), and stores a packet received from the "New RN" in the "Up_Buffer" (405). When the "Old PDSN" receives the "Handoff_Gen" message from the "New PDSN", it forwards the message back to the home agent (404) and the "Handoff_Ack" message to the "New PDSN" (406). At this time, the "New PDSN" waits for a "Handoff_UpEnd" message from the "Old PDSN" while storing a packet coming from the "New RN" in the "Up_Buffer".

And, "Old PDSN" transmits the packets stored in "Up_Buffer" to the home agent, and ends the packet sequence control by sending a "New PDSN" and a "Handoff_UpEnd" message to the home agent when the transmission is completed (407, 408). After that, it is idle.

On the other hand, the "New PDSN" receives the "Handoff_UpEnd" message from the "Old PDSN", terminates the packet sequence control, switches to the normal data transmission state, and transmits the packet stored in the "Up_Buffer" to the home agent (409). .

5 is a flowchart illustrating a method of controlling a packet sequence for mobility support when an RN handoff occurs in a PDSN according to the present invention, and shows a multicast group for supporting micro mobility when a mobile station moves between RNs and RNs in a PDSN. It represents a mechanism-based endless handoff algorithm.

The mobile station is serviced by the PDSN and the RN managing the area where the mobile station exists. When the mobile station is moving the RN area, the mobile station can obtain the signal strength of the RN adjacent to the area where the mobile station exists. Suppose that to report to, the handoff processing procedure of the proposed multicast group-based handoff algorithm is as follows.

First, the mobile station reports its location information to the PDSN (501), which stores the information about it. Here, the location information consists of the number of the mobile station, the reporting time, and the signal strength of the adjacent RN. The PDSN predicts the moving direction and the speed of the mobile station by using the location information reported from the mobile station and the location information and the moving environment information including the location information of the RN in the PDSN (502).

Next, the PDSN configures the RNs on the expected movement path of the mobile station into a multicast group by using the predicted movement direction and speed of the mobile station (503). At this time, the PDSN records the expected handoff time of each member RN and informs it to each RN (504). Next, the PDSN sends the packet to be sent to the mobile station to the member RNs of the multicast group, and the RN where the mobile station is currently located sends the packet to the mobile station. The member RNs store only the packet after each handoff expected time (505).

The mobile station then moves to the adjacent RN, which informs the RN to which the last received packet number was transferred (new) (506).

The new RN then transmits the packet after the last number among the stored packets to the mobile station (507). Since the handoff is handled using the multicast connection, the mobile station can receive a continuous service of data from the RN, and the RN stores only packets after the expected handoff, thereby reducing the buffer overhead of the RN.

Looking at the process of predicting the expected handoff time in more detail as follows.

In the present invention, when the handoff occurs, the mobile station predicts an expected handoff time to provide a continuous handoff. To this end, the mobile station periodically informs the PDSN of the location information, which has factors such as signal strength and reporting time of adjacent RNs. The estimated handoff time is estimated using the location information and the signal strength, which is the database having the actual measured RN signal strength in the RN region, and predicts the position of the mobile station, and reaches the RN boundary having the largest value among the signal strengths reported from the mobile station. Find the distance and then divide it by the speed of the mobile station to predict the expected handoff time. At this time, the mobile station speed prediction of the PDSN predicts the position according to the signal strength of the RN among the position information periodically reported by the mobile station by using the placement information, and divides the difference of the position according to the reporting time of the mobile station by the mobile station reporting time difference. Find the speed. Based on this, the PDSN transmits only data after the expected handoff time to the RN, and the RN also stores only data after its expected handoff time in the buffer.

Looking at the multicast group configuration process in more detail as follows.

Multicast group configuration means that the mobile station selects adjacent RNs based on the RN currently being serviced and sets them as a group. At this time, in order to provide a continuous service to the mobile station, the size of the group and the overhead of the buffer of each member belonging to the group have the following correlation.

In the present invention, when the PDSN determines a multicast group, the mobile station does not determine the group member from adjacent RNs of the RN currently being serviced, but the location information reported periodically by the mobile station and the placement information of the RNs of the PDSN. By predicting the moving direction and the speed of the mobile station by using the RN having the signal value with the largest RN signal strength among the expected paths of the mobile station as a moving object, the adjacent RNs are selected as a multicast group. At this time, the network efficiency can be increased and the overhead can be reduced by determining, as members, up to RN having an appropriate signal strength value according to the predicted speed of the mobile station. In addition, the multicast group member join time is determined by subtracting the estimated handoff time from the sum of the time for selecting the RN members of the group and the time for joining the member RNs.

In order to apply the proposed algorithm for continuous handoff based on multicast group configuration between RNs in PDSN, the following connection management information is maintained in PDSN, RN and mobile station.

First, the connection management information of the mobile station is as follows.

The mobile station establishes a connection with the fixed host (FH) through the RN and the PDSN to communicate. The connection related information maintained by the mobile station is a current PDSN number, a current RN number, information on a current connection, a connection number, and a number of a last received packet. This is described as follows.

The current RN number and the current PDSN number refer to the current position of the mobile station, and the PDSN number can be obtained using the RN number. In addition, since the mobile station can establish a call with several counterpart hosts, the mobile station maintains information on the connection currently connected by the connection number CONID and the last packet number. The last packet number field is the number of packets successfully received by the mobile station from the RN. It is used to determine the packet that the next RN will send to the mobile station during handoff processing. It is also used to control the packet sequence between the RN and the mobile station to avoid duplication of data. do.

Second, look at the connection management information of the RN as follows.

In the RN-managed area, the following connection information table is maintained in order to store the multicast packets in advance in preparation for movement on the mobile station and the expected path of the current connection. Are connection information table, group number, mobile station number, connection number, expected handoff time, and the like. Since the mobile stations existing in the area managed by the RN constitute respective multicast groups corresponding thereto, the RN configures group number, mobile station number, and connection number fields in order to maintain connection information of each mobile station. These are used to identify the mobile station's connection, and the Forecasted Handoff Time (FHOT) is used by the RN to store packets after the expected handoff time. This can determine the amount of data that the RN buffers.

Third, the connection management information of the PDSN is as follows.

The PDSN manages all mobile station connection information and multicast group information in the area managed by the PDSN, and maintains a location information table for tracking the location of the mobile station and a mobile environment table for estimating the expected path of the mobile station. Here, the mobile environment table includes a group number, an RN number, a mobile station number, an expected handoff time, a join request time, a location information table, a mobile environment table, and the like.

The location information table includes the mobile station number, report time, RN number, and signal strength. The Position Information Table (PINFORTABLE) shows the signal strength (SS) of the adjacent RN, which is periodically reported by the mobile station, the reported time (RT: Report Time), and the number of the RN currently connected. RNID) and mobile station number (mobile station ID). In addition, by using a multicast group table (MGTABLE) to maintain information about the expected handoff time (FHOT) of each RN belonging to the group in the area managed by the PDSN.

The mobile environment table includes a location of a mobile station, an estimated location, an estimated speed, and a list of group members. The mobile environment table (MENVTABLE) is a static table that calculates a moving direction and speed of a mobile station to determine a mobile host. Used to form a multicast group. The mobile environment table is constructed by the signal strength of the RNs measured at each location according to the actual mobile station's movement.

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The present invention described above is not limited to the above-described embodiment and the accompanying drawings, and it is common in the art that various substitutions, modifications, and changes can be made without departing from the technical spirit of the present invention. Will be evident to those who have knowledge of

As described above, when the mobile station moves out of the current PDSN region to another PDSN region and a handoff occurs, handoff sequence control is applied to reduce the reordering and loss of data. .

In addition, the present invention has an effect that by applying a multicast group configuration mechanism when the mobile station moves between RNs in the PDSN, the RN stores the data to be transmitted to the mobile station in the buffer in advance to support the continuous handoff when a handoff occurs .

In addition, the present invention has the effect of increasing the efficiency of the network by slowing down the multicast group join time as much as possible within the range that does not interfere with the continuous connection service.

In addition, the present invention can suppress unnecessary transmission since the PDSN transmits data only after the expected handoff time after the multicast join, and since the RN also stores only the data after the expected handoff time, the buffer overhead is reduced. There is an effect that can be reduced.

Claims (16)

In the continuous packet sequence control method for mobility support in a wireless communication network, A multicast group constructing step in which a packet data serving node (PDSN) configures RNs (Radio Networks) on an expected movement path of the mobile station by using a movement direction and a speed of the mobile station; An expected handoff time notification step, wherein the PDSN notifies each estimated handoff time to each multicast group member RN; Transmitting, by the PDSN, a packet to be transmitted to the mobile station to member RNs of a multicast group; A packet storing step in which the RN in which the mobile station is currently located transmits a packet to the mobile station, and the other multicast group member RNs store the packet after each estimated handoff time; A packet number informing step, in which the mobile (new) RN is informed of the number of the packet last received by the mobile station from the mobile station as the mobile station moves to an adjacent RN and an inter-RN handoff occurs; And A second packet transmission step of transmitting a packet after a last number among the packets in which the new RN is stored to the mobile station; Endless packet sequence control method for mobility support in a wireless communication network comprising a. The method of claim 1, The multicast group configuration step, The PDSN receiving and storing location information of the mobile station; Predicting, by the PDSN, a moving direction and a speed of the mobile station using location information, area information, and moving environment information; And Configuring, by the PDSN, RNs on the expected movement path of the mobile station into a multicast group by using the predicted movement direction and speed of the mobile station; Endless packet sequence control method for mobility support in a wireless communication network comprising a. The method of claim 2, The location information of the mobile station is And a signal strength of a neighboring RN, the number of mobile stations, a reporting time, and a continuous packet sequence control method for mobility support in a wireless communication network. The method according to any one of claims 1 to 3, The estimated handoff time is The location of the mobile station is estimated using the location information and the signal strength, which is a database having the actual measured RN signal strength in the RN region, and the distance from the mobile station to the RN boundary having the largest value is reported. A method of controlling a continuous packet sequence for mobility support in a wireless communication network, wherein the value is obtained by dividing the result by the speed of the mobile station. The method of claim 4, wherein The mobile station speed prediction process, It estimates the position according to the signal strength of the RN of the position information periodically reported by the mobile station by using the batch information, and obtains the mobile station speed by dividing the difference of the position according to the reporting time of the mobile station by the difference of the mobile station reporting time. Continuous packet sequence control method for mobility support in wireless communication network. The method according to any one of claims 1 to 3, The multicast group configuration process, Rather than determining the group member by neighboring RNs of the RN currently being serviced, the mobile station uses the location information reported periodically by the mobile station and the arrangement information of the RNs of the PDSN. Endless packets for mobility support in a wireless communication network which predicts speed and selects RNs having the largest signal value of the RN signal strength among the predicted paths of the mobile station as moving objects and selects RNs adjacent to the multicast group. Sequence control method. The method of claim 6, Members of the multicast group are: In a wireless communication network, the joining time is determined by subtracting the sum of the time for selecting the RN member of the multicast group and the time taken to join the multicast member RN from the estimated handoff time of the mobile station. Continuous packet sequence control method for mobility support. delete delete delete delete delete delete delete delete delete

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