KR100869812B1 - Method for allocating a location registration channel at a node-b of wcdma, and mobile communication system using this method - Google Patents

Abstract

The present invention relates to a method for allocating a location registration channel at a node B of a WCDMA, and facilitates location registration even when a call is congested in a WCDMA network, thereby minimizing interference with neighboring terminals due to repeated attempts of location registration. It is aimed at making it possible. The channel allocation method according to the present invention comprises the steps of measuring call occupancy for traffic channels and occupying by call among the traffic channels when the call occupancy rate for the traffic channels increases by more than a predetermined value. And assigning a predetermined number of channels, which are not, to a dedicated channel for location registration.

Description

METHODO FOR ALLOCATING A LOCATION REGISTRATION CHANNEL AT A NODE-B OF WCDMA, AND MOBILE COMMUNICATION SYSTEM USING THIS METHOD}

1 is a block diagram of a WCDMA mobile communication system to which the present invention is applied.

2 is a flowchart illustrating a location registration process in a WCDMA mobile communication system to which the present invention is applied.

3 is a flowchart for explaining a method for allocating a location registration channel according to the first embodiment of the present invention.

4 is a flowchart for explaining a method for allocating a location registration channel according to a second embodiment of the present invention.

5A and 5B are diagrams illustrating a channel occupation state according to the present invention.

The present invention relates to a method for allocating a location registration channel in a mobile communication system. In particular, the present invention relates to a method for allocating a location registration channel in a mobile communication system in which a channel element is allocated from a base station system to send and receive a location registration message. It is about.

In conventional CDMA, since only an overhead channel is used for location registration, a separate channel element does not need to be allocated. However, in WCDMA network, the traffic channel for the call and the channel for location registration are not distinguished, and the mobile communication terminal is allocated a channel element from the base station for the location registration and occupies a signaling radio bearer (SRB), and then the location with the base station. You must send and receive registration messages. Therefore, when the subscriber calls of certain base stations are congested due to event events such as graduations and performances, the location registration is not successful because of the lack of DPCH (Dedicated Physical Channel) channel elements, and the retry of location registration is performed by a mechanical mechanism. If it is made continuously, the interference to the surrounding user terminal is continuously increased, the wireless environment is worse. In addition, subscribers who do not register their location may not be able to receive a phenomenon.

In other words, there is a narrowing of coverage of the uplink from the user terminal to the base station and the downlink from the base station to the user terminal during call congestion. This is because, in the downlink side, the Ec / Io (signal-to-noise ratio) of the terminal is sharply lowered because the base station allocates power to each of the user terminals. In terms of uplink, the same number of terminals simultaneously transmits a certain amount of power, so the interference is increased proportionally, and in order to overcome this interference (i.e., to satisfy the target block error rate), This is because power must be increased at the same time. In a situation where the uplink is very poor during congestion, continuous power-up of a terminal for location registration may further require power of another terminal. Thus, the overall uplink coverage can be greatly reduced.

Accordingly, an object of the present invention is to smoothly register a location even when a call is congested in a WCDMA network so that interference with neighboring terminals due to repeated attempts of location registration by a terminal is minimized.

In order to achieve the above object, the present invention variably secures several dedicated channels for location registration among channel elements when a subscriber call of a specific base station is congested.

The present invention provides a method for allocating a location registration channel at Node B of WCDMA, comprising: measuring a call state for traffic channels; and when an event indicating call congestion occurs as a result of the measurement of the call state, And allocating a predetermined number of channels not occupied by the call to a dedicated channel for location registration.

Advantageously, the state of the measured call is call occupancy for the traffic channels, and the event is when call occupancy for the traffic channels is greater than or equal to a predetermined value. If the call occupancy rate for the traffic channels is less than a predetermined value, the channel for traffic and the channel for location registration are shared. In addition, the state of the call to be measured is whether the call is incomplete or not, and the event is a case where the cause of the call incomplete occurs more than a predetermined number of times. In particular, the call incomplete is due to the connection failure of the call.

In addition, the present invention is a mobile communication system in which a mobile communication terminal is assigned a traffic channel and transmits and receives a location registration message with a base station, the means for measuring the call state of the traffic channels, and displays the call congestion result of the call state measurement And a means for allocating a predetermined number of channels not occupied by a call among the traffic channels as a dedicated channel for location registration.

According to the present invention, even when a call is congested in the WCDMA network, location registration can be smoothly performed, and the interference effect on the neighboring terminal caused by the repeated location registration attempt of the terminal can be greatly reduced.

Hereinafter, with reference to the accompanying drawings will be described embodiments of the present invention; In the drawings, the same reference numerals are used to indicate the same or similar components.

1 is a block diagram of a wideband code division multiple access (WCDMA) mobile communication system 20 to which the present invention is applied. As shown, the WCDMA mobile communication system 20 includes Node B / RNC 210, SGSN 270, GPRS 280, GGSN 290, Asynchronous MSC 220, and No. 7 common signaling network 230, SMSC (Short Message Service Center: 240), SCP (250), HLR (Home Location Register: 260).

First, the Node B serves as a base station for wireless section communication with the mobile communication terminal 10, and a Radio Network Controller (RNC) controls the Node B. The asynchronous exchange 220 is connected to the wireless network controller 210 performs a call exchange for providing a service to the mobile communication terminal (10). No. 7 The common signal network 230 is connected to a short service center (SMSC: 240), intelligent network controller (SCP: 250), home location register (HLR: 260). The Serving GPRS Support Node (SGSN) 270 is connected between the radio network controller 210 and the General Packet Radio Service (GPRS) 280 and maintains a location track of the mobile communication terminal 10 and performs access control and security functions. do. The Gateway GPRS Support Node (GGSN) 290 is connected between the GPRS 280 and the Internet 30 to support interworking with external packets.

2 is a flowchart illustrating a location registration process in WCDMA. As shown, location registration is mainly RRC (Radio Resource Control) connection (S102 to S106), Routing Area Update (Rout) Request (RAU) request (S108), authentication (S110), RAU approval and completion (S112, S114) ), Is performed through the steps of RRC disconnection (S116).

RRC (Radio Resource Control) connection is a step that must be made before call setup, and establishes a radio path for transmitting and receiving control information between the RNC 210 and the user terminal 10. The RRC connection process can be viewed as a Signaling Radio Bearer (SRB) occupation process.

First, when attempting to establish an RRC connection due to location registration, call attempt, or response to paging of the network, the user terminal 10 in the standby state transmits an RRC connection request message to the Node B / RNC 210 (S102). ). In this case, the RRC connection request message includes an initial UE identifier of the user terminal and an RRC establishment cause. The initial terminal identifier is a terminal unique identifier, so that the terminal can be identified anywhere in the world. The user terminal 10 transmits an RRC connection request message and simultaneously drives a timer, and rejects an RRC connection setup message or an RRC connection from the node B / RNC 210 until the timer expires. If no Reject) message is received, the RRC connection request message is retransmitted. At this time, the maximum number of transmission of the RRC connection request message is limited to a specific value.

Next, the Node B / RNC 210 receiving the RRC connection request message from the user terminal 10 accepts the RRC connection request of the user terminal when there is sufficient radio resources, and transmits an RRC connection establishment message, which is a response message, to the terminal. (S104). At this time, the RRC connection setup message includes an initial terminal identifier and a radio network temporary identity (RNTI) and radio bearer setup information. The radio network temporary identifier is a terminal identifier assigned by the Node B / RNC 210 to identify a terminal in a connected state, and is used only when an RRC connection exists, and is used only in a network. As such, after the RRC connection is established, the terminal 10 communicates with the network using the temporary network identifier instead of the initial terminal identifier. The reason is that the initial terminal identifier is a unique identifier of the terminal because it may be leaked if it is frequently used. Therefore, for security reasons, the initial terminal identifier is used only temporarily during the RRC connection process, and then the temporary network identifier is used.

The user terminal 10 receiving the RRC connection setup message first compares the initial terminal identifier included in the message with its own identifier and checks whether the received message is a message transmitted to the user. If the message is transmitted to itself as a result of the check, the terminal 10 stores the radio network temporary identifier assigned by the network, and transmits an RRC connection setup complete message to the network by using this (S104). At this time, the RRC connection setup complete message includes the degree of performance of the terminal. When the terminal successfully transmits the RRC connection setup complete message, the terminal establishes an RRC connection with the network and transitions to the RRC connection state.

In case of insufficient radio resources, the network transmits an RRC Connection Reject message that rejects the RRC connection request of the user terminal. At this time, the RRC connection rejection message includes the initial terminal identifier and the reason for rejection, so that the terminal can know why it was rejected. Upon receiving the RRC connection rejection message, the terminal stops the RRC connection attempt after confirming that it is its message through the initial terminal identifier. If the initial terminal identifier including the RRC connection rejection message is different from its initial terminal identifier, the terminal discards the received message and continues to receive the RRC connection establishment message or the RRC connection rejection message.

After the RRC connection is completed, the service or location registration process for the general call is performed. First, when a service for a general call is performed, a radio bearer setup process is performed after authentication, which is a process of establishing a path between the user terminal 10 and the core network 40. . However, in the location registration, the user terminal 10 and the core network 40 exchange a routing area update message via the node B / RNC 210 without undergoing the radio bearer setup process after the authentication process (S110) (S112, S114), the call is released immediately (S116).

The concept of routing area was introduced into the General Packet Radio System (GPRS) network for data packet routing and mobility management. The routing area is used by the network to locate the user terminal when data packet transmission to the user terminal is initiated. The routing area consists of a plurality of cells. When the user terminal is powered on, the user terminal reports the location area and the routing area to the network, and switches from the idle state to the standby state. In the standby state, only the routing area of the user terminal is recognized by the network, and no traffic channel on the air interface is allocated for the user terminal. When a Serving GPRS Support Node (SGSN) transmits a packet to a user terminal in a standby state, the user terminal should be paged. Upon receiving the packet paging message, the user terminal transmits its cell location to the SGSN and enters the active state. Only when the user terminal is in an active state does the network allocate resources necessary for data transmission between the user terminal and the network. If no data transfer occurs between the user terminal and the network for a period of time (commonly referred to as a "ready timer"), the user terminal may transition to a standby state, thereby allowing the network to allocate resources for other user terminals. have. The ready timer is always set to a few to several tens of seconds, so the user terminal is in a standby state most of the time. Thus, in order to locate the user terminal for data transmission, the network generally must page all the cells in the routing area.

The RAU request message includes a Temporary Ligic Link Identity (TLLI), a new Cell Indentity (CI), a former Routing Area Identity (RAI), and a new RAI. CI is added at NodeB / RNC 210 to reduce the load on the air interface. The core network 40 validates the presence of the user terminal 10 in the new routing area. If the existence of the user terminal 10 is not valid in the new routing area due to regional, national, or inter-country constraints, the core network 40 rejects location registration for an appropriate reason. On the other hand, if all the checks are successful, the core network 40 performs location registration for the new routing area, and a new TLLI may be allocated. The RAU response message may include the TLLI and the reason for rejection. If the TLLI has been changed, the user terminal 10 approves the new TLLI by sending a RAU complete message including the changed TLLI to the CN 40. If the RAU procedure fails despite the maximum allowable number of attempts, or if the RAU grant message sent by the CN 40 to the user terminal 10 indicates a rejection, the user terminal 10 returns to the idle state. Enter

Routing area update (RAU) is performed in an active state and a standby state. The RAU is triggered or periodically triggered when the user terminal 10 crosses into a new routing area (RA). If triggered periodically, the time interval is set by the network. The RAU is also performed when the user terminal 10 changes from the idle state to the standby state. This typically occurs when the user terminal 10 is powered on.

3 is a flowchart illustrating a location registration channel allocation method according to a first embodiment of the present invention.

First, the ratio of the traffic channel occupied by the call among the traffic channels of the node B / RNC 210 is measured (S202).

Next, the measurement results are used to calculate the percentage of traffic channels occupied by the call (call occupancy), and if the call occupancy for the traffic channels is less than 95%, for example in normal mode (i.e. ) Channels are allocated (S204, S206). That is, the channel elements are shared with a channel for traffic and a channel for location registration. However, when the call is congested and the call occupancy rate of the traffic channels increases to 95% or more, for example, a predetermined number of channels among the traffic channels not occupied by the call are allocated as dedicated channels for location registration. (S204, S208). Through this, in any case, by securing a channel for location registration only, even if the call is congested, the location registration by the new terminal is smoothly performed.

The problem in designating a channel for location registration as in the present invention is that the number of traffic channels is somewhat reduced. However, since there are only one or two location registration channels, the damage is not significant. In addition, since traffic is posted by a user, but location registration is self-raised by a mechanical mechanism, the effect of interference on nearby users is more likely to repeatedly attempt location registration in consideration of persistence. Therefore, even if the number of traffic channels is slightly reduced, it is advantageous to reduce the effect of interference on neighboring users.

Here, 95% of call occupancy, which is the standard for dedicated channel allocation, is just one example, and it varies depending on the network characteristics, so it can be changed by the operator's know-how. This is because the amount of interference on each base station is different even if the same traffic channel occupancy. Therefore, it is possible to detect a case where a large number of specific cause of call incompleteness such as cause of call connection failure that occurs in the system as allocation criteria occurs.

4 is a flowchart illustrating a method for allocating a location registration channel according to a second embodiment using a rate of occurrence of a call connection failure instead of a channel occupancy rate.

First, the number of times a cause of a call connection failure occurs among the traffic channels of the Node B 210 is measured (S302).

Next, the measurement result is used to calculate the rate at which the cause of the call failure occurs (call failure rate), and if the call failure rate for the traffic channels is less than 95%, for example, the channels are allocated in all regular operations (S304, S306). That is, the channel elements are shared with a channel for traffic and a channel for location registration. However, when the call congestion increases and the call failure rate for traffic channels increases to 95% or more, for example, a predetermined number of channels among traffic channels not occupied by the call are allocated as dedicated channels for location registration. (S304, S308). Through this, in any case, by securing a channel for location registration only, even if the call is congested, the location registration by the new terminal is smoothly performed. In this case, the 95% call failure rate is just one example and can be changed by the operator's know-how.

5 is a view illustrating a channel occupancy state according to the present invention, FIG. 5A illustrates a case where a dedicated channel for location registration is not designated, and FIG. 5B illustrates a case where a dedicated channel for location registration is designated. .

In general, Node B's Digital Signal Processor (DSP) uses six of the 96 channel elements as overhead channels and 90 as traffic channels. The shaded portions in FIGS. 5A and 5B indicate the occupied channels. In the channel allocation shown in FIG. 5A, a channel for traffic and a channel for location registration are shared. However, in the channel allocation shown in FIG. 5B, a channel used only for location registration is allocated and used.

The foregoing embodiments are given by way of example to enable those skilled in the art to easily understand and to practice the present invention, and are not intended to limit the scope of the invention. Therefore, those skilled in the art should note that various modifications or changes can be made to the above-described embodiment. The scope of the invention is determined in principle by the claims that follow.

According to the present invention, even when a call is congested in the WCDMA network, location registration can be performed smoothly, and the effect of interference to neighboring terminals due to repeated location registration attempts of the terminal can be greatly reduced.

Claims (10)

In the method of allocating a location registration channel at Node B of WCDMA, Measuring the state of the call for the traffic channels; Allocating a predetermined number of channels not occupied by a call among the traffic channels as a dedicated channel for location registration when an event indicating call congestion occurs as a result of measuring the call state; And a location registration channel assignment method. The method of claim 1, The measured call state is a call occupancy rate for the traffic channels, and the event is a call occupancy rate for the traffic channels. The method of claim 2, And if the call occupancy rate for the traffic channels is less than a predetermined value, a channel for traffic and a channel for location registration are shared. The method of claim 1, The status of the measured call is whether the call is incomplete or not, and the event is a case where the cause of the call incomplete has occurred more than a predetermined number of times. The method of claim 4, wherein The incompleteness of the call is due to the failure of the call connection. In a mobile communication system in which a mobile communication terminal is assigned a traffic channel and transmits and receives a location registration message with a base station, Means for measuring the state of the call for the traffic channels; Means for allocating a predetermined number of channels not occupied by a call among the traffic channels as a dedicated channel for location registration when an event indicating call congestion occurs as a result of the measurement of the call state; Mobile communication system characterized in that it comprises. The method of claim 6, The measured call state is a call occupancy rate for the traffic channels, and the event is a case in which the call occupancy rate for the traffic channels is greater than or equal to a predetermined value. The method of claim 7, wherein And if the call occupancy rate for the traffic channels is less than a predetermined value, a channel for traffic and a channel for location registration are shared. The method of claim 6, The state of the measured call is whether the call is incomplete or not, and the event is a case where the cause of incompleteness of the call occurs more than a predetermined number of times. The method of claim 9, The incompleteness of the call is due to the failure of the call connection.

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