WO2008041816A1

WO2008041816A1 - System and method for reducing size of initial uplink message in mobile communication system

Info

Publication number: WO2008041816A1
Application number: PCT/KR2007/004821
Authority: WO
Inventors: Gert Jan Van Lieshout; Himke Van Der Velde
Original assignee: Samsung Electronics Co., Ltd.
Priority date: 2006-10-03
Filing date: 2007-10-02
Publication date: 2008-04-10
Also published as: GB2442601B; GB0719353D0; GB2442514A; KR20080031131A; GB0619509D0; KR101378629B1; GB2442601A

Abstract

Provided is a system and method for reducing the size of an initial uplink message in a mobile communication system. The initial uplink message is configured by omitting at least one of an identity (ID) indicating a Public Land Mobile Network (PLMN), i.e., a PLMN ID, and an ID indicating a Tracking Area (TA), i.e., a TA ID, thereby reducing the size of the initial uplink message.

Description

SYSTEM AND METHOD FOR REDUCING SIZE OF INITIAL UPLINK MESSAGE IN MOBILE COMMUNICATION SYSTEM

Technical Field

The present invention relates to an initial access procedure of a mobile communication system, and in particular, to a system and method for reducing the size of an initial uplink message transmitted and received between a mobile terminal and network elements.

Background Art

A Universal Mobile Telecommunications System (UMTS) is a 3^rd- Generation (3G) asynchronous mobile communication system that is based on a European mobile communication system Global System for Mobile Communications (GSM) and General Packet Radio Services (GPRS) and uses wideband Code Division Multiple Access (CDMA).

At present, the 3 G Partnership Project (3 GPP) in charge of UMTS standardization is discussing about a Long Term Evolution (LTE) system as a next generation mobile system for the UMTS system.

The LTE system focuses on feature enhancement of Universal Terrestrial Radio Access (UTRA) and optimization of a UTRA Network (UTRAN) architecture. The LTE system also aims to provide, for example, high data rates, flexibility in frequency allocation, and continued cost reduction.

Considering such a service environment, it is desirable to avoid the use of an additional uplink message in an initial uplink message transmission/reception procedure in order to reduce a delay in transition of a Radio Resource Control (RRC) state of a User Equipment (UE).

In other words, considering a current situation where a desirable initial uplink message structure and a desirable initial uplink message transmission/reception procedure in the state transition of the UE in a next generation mobile communication system are not defined in detail, a detailed scenario for an uplink message transmission procedure during an initial access procedure is required. There is also a need for detailed discussion about how the initial uplink message is to be configured.

Technical Objects

To solve the foregoing problems, the present invention provides a system and method for configuring an initial uplink message having an optimized size in an initial access procedure of a mobile communication system.

The present invention also provides a system for configuring an initial uplink message by optimizing the size of the initial uplink message and transmitting the initial uplink message having the optimized size in the state transition of a UE in a next-generation mobile communication system.

The present invention also provides an initial access method for configuring an initial uplink message by optimizing the size of the initial uplink message and transmitting the initial uplink message having the optimized size in the state transition of a UE in a next-generation mobile communication system.

The present invention also provides a system and method for configuring and transmitting an initial link message by minimizing a time delay in the state transition of a UE in a next-generation mobile system.

Technical Solutions

To achieve the foregoing objects, there is provided a method for reducing a size of an initial uplink message transmitted and received between a mobile terminal and network elements in a mobile communication network system. The method includes configuring the initial uplink message by omitting at least one of an identity (ID) indicating a Public Land Mobile Network (PLMN), which will hereinafter be referred to as a PLMN ID, and an ID indicating a Tracking Area (TA), which will hereinafter be referred to as a TA ID, within the initial uplink message and transmitting and receiving the configured initial uplink message.

Preferably, the configuring of the initial uplink message includes configuring the initial uplink message by omitting at least one of the PLMN ID and the TA ID, if one of a first condition that a network element of a cell in which the mobile terminal that transmits the initial uplink message is located broadcasts a single PLMN ID or a single TA ID, and a second condition that an ID to be signaled by the mobile terminal using the initial uplink message is equal to a value broadcasted in the first condition is satisfied.

Preferably, the configuring of the initial uplink message includes configuring the initial uplink message by omitting at least one of the PLMN ID and the TA ID, if one of a third condition that a network element of a cell in which the mobile terminal that transmits the initial uplink message is located broadcasts a plurality of PLMN IDs or a plurality of TA IDs, and a fourth condition that an ID to be signaled by the mobile terminal using the initial uplink message is equal to at least one of values broadcasted in the third condition is satisfied.

Effects of the Invention

According to the present invention, in an initial access procedure of a mobile communication system, it is not necessary to include full IDs of a network element in an initial uplink message for transmission, thereby reducing the size of the initial uplink message. By doing so, in an initial access procedure of a next- generation mobile communication system, a requirement for transmission of an initial message having a limited size can be satisfied. Moreover, due to no need to separately transmit an initial message, the efficiency of radio resources can be provided.

In other words, by checking an identical tracking area (TA) ID, it is not necessary to signal a corresponding value, thereby reducing the size of the initial uplink message. -A-

Therefore, according to the present invention, the size of the initial uplink message is further reduced in the next-generation mobile communication system, thereby sufficiently satisfying a requirement for a limited message size.

Brief Description of the Drawings

FIG. 1 schematically illustrates a flow of information transmitted and received between network elements in a next-generation mobile communication system to which the present invention is applied;

FIG. 2 schematically illustrates an initial access procedure between a User Equipment (UE) and a base station (eNB) in a next-generation mobile communication system to which the present invention is applied; and

FIG. 3 schematically illustrates an initial access procedure between the UE and the eNB in a next-generation mobile communication system to which the present invention is applied.

Best mode for carrying out the Invention

Hereinafter, an exemplary embodiment of the present invention will be described in detail with reference to the annexed drawings. Like reference numerals and symbols refer to like elements throughout drawings. In the following description, a detailed description of known functions and configurations incorporated herein has been omitted for conciseness.

The present invention relates to an initial access procedure and defines a process of transmitting and receiving an initial message by minimizing a delay in the transition of a User Equipment (UE) from a Long Term Evolution (LTE) IDLE state (LTEJDLE) to a LTE ACTIVE state (LTE ACTIVE).

First, an LTE system under discussion by the 3 G Partnership Project (3GPP) will be briefly defined.

A basic one among a plurality of requirements for the LTE system is fast transition from LTE IDLE to LTE ACTIVE. In relation to the fast transition, C-plane latency has to be considered as follows. Significantly reduced C-plane latency a) Transition time (excluding downlink paging delay and NAS signaling delay) of less than 100ms from a camped state such as Release 6 Idle Mode to an active state such as Release 6 CELL DCH is set in a user plane.

LTE IDLE and LTE ACTIVE can be defined as follows. In the LTE system, a Radio Resource Control (RRC) protocol state in an E-UTRAN can be defined as 1) LTEJDLE, 2) LTE ACTIVE, and 3) an LTE DETACHED state (hereinafter, 'LTE DETACHED').

Inactivity

- Release Cell Radio Network Temporary Identity (C-RNTI)

- Allocate DRX for Paging Channel (PCH) New traffic

- Allocate C-RNTI

2) LTE_ACTIVE

*RRC: RRC CONNECTED

* RRC Context in network:

- Includes all information necessary for communication

* Allocated UE-Id(s):

- International Mobile Station Identity (IMSI)

- ID unique in Tracking Area (TA-ID)

- ID unique in Cell (C-RNTI)

- one or more Internet Protocol (IP) addresses

* UE position:

- Known by network at Tracking Area (TA) level

* Mobility:

- Handover

* Downlink (DL)/Uplink (UL) activity:

- UE is configured with Discontinuous Reception (DRX)/Discontinuou: Transmission (DTX) periods.

Perform Registration

- Allocate C-RNTI, TA-ID, IP address

- Perform Authentication

- Establish security relation

Change of PLMN/deregistration

- Deallocate C-RNTI, TA-ID, IP address 3) LTE_DET ACHED

* RRC: NULL

* RRC Context in network:

- Does not exist

* Allocated UE-Id(s):

- International Mobile Station Identity (IMSI)

* UE position:

- Not known by network

* Mobility

- PLMN/ Cell reselection

* Downlink (DL)AJplink (UL) activity: - None

Timeout of periodic TA-update

- Deallocate C-RNTI, TA-ID and IP address

A Mobility Management Entity (MME) of a communication system configures and manages a UE context in relation to the state of the UE. On the other hand, an enhanced Node B(eNB or base station), does not configure a UE context for a UE in LTE IDLE and configures and manages only a UE context for a UE in LTE_ACTIVE.

In the state transition of the UE, the UE re-establishes a previous IP connectivity service. Although a detailed operating procedure of each network element of a mobile communication system for the service connectivity establishment have not yet been defined, a schematic procedure for high-level connectivity establishment can be described as illustrated in FIG. 1. FIG. 1 schematically illustrates an information flow in an initial access procedure of a next-generation mobile communication system to which the present invention is applied. FIG. 1 illustrates a procedure for reducing a delay in state transition, including a procedure for transmitting and receiving information for paging and C-plane establishment.

Referring to FIG. 1, a UE 100 is in LTE IDLE in step 130. A Mobility Management Entity (MME)/User Plane Entity (UPE), which is a network node of a system, maintains a service context for the UE 100 for a minimum default IP connectivity service.

The MME/UPE 120 senses the reception of data packet from an upper layer or another UE in step 135 and checks the state of the UE 100 and a current TA in step 140.

In step 145, the UE 100 is paged.

In step 150, the UE 100 transmits a radio resource connection request message to the MME/UPE 120. The radio resource connection request message includes Non Access Stratum (NAS) equivalent information for a service request for data/signaling.

In step 155, the radio resource connection request message from the UE and the paging procedure are correlated and then DL data transmission starts on default radio resources.

In step 160, the MME/UPE 120 transmits a radio resource setup message to the UE 100. The radio resource setup message contains NAS equivalent information for service accept and activate PDP context, and Access Stratum (AS) equivalent information for radio resource connection Acknowledgement (Ack) information, a security mode command, and a Radio Access Bearer (RAB) assignment request/Radio Bearer (RB) setup. Upon receipt of the radio resource setup message, the UE 100 transmits a radio resource setup Ack message to the MME/UPE 120 in step 165. The radio resource setup Ack message contains NAS equivalent information for activate PDP context accept and AS equivalent information for security mode complete, and RAB assignment response/RB setup complete.

Steps 160 and 165 involve resource setup for the default IP access service and a service having a different Quality of Service (QoS) than that of the default IP access service.

Procedures that are sequentially performed in existing 3 G mobile communication systems, which will hereinafter be referred to as legacy systems, in association with the radio access procedure can be performed in parallel in a next-generation mobile communication system such as an LTE system and a System Architecture Evolution (SAE) system.

An AS procedure for establishing radio connection can be combined with an NAS procedure for re-activating previously established SAE bearers. Hereinafter, the service request/accept message will be referred to as the NAS equivalent information.

An initial radio access procedure between the UE and the eNB has not also been agreed. A high level for the initial radio access procedure will be described briefly with reference to FIG. 2.

FIG. 2 schematically illustrates an initial access procedure between a UE and an eNB in a next-generation mobile communication system according to an exemplary embodiment of the present invention.

Referring to FIG. 2, a UE 200 transmits a random access preamble message to an eNB 210 in step 215.

In step 220, the eNB 210 transmits a random access response message to the UE 200. The random access response message contains timing advance, scheduling grant, C-RNTI information, and the like.

The UE 200 transmits an L3 message to the eNB 210 in step 225 and receives an L3 message response message from the eNB 210, thereby completing the initial access procedure in step 230.

In initialization of the initial access procedure, the UE 200 is not allocated dedicated resources and is not assigned a short cell specific ID, and its uplink timing is not aligned with the network. Thus, an initial message transmitted by the UE 200 uses a contention-based channel for asynchronous uplink transmission and information that can be transmitted on such a channel is limited to 4 - 6 bits. Although information that can be included in step 225 may be set larger, it is still quite limited for a UE at a cell edge.

Some initial analysis shows that a UE can transmit approximately 100 bits when using 2 HARQ retransmission. The 2 HARQ retransmission is performed in a bandwidth of 1.25 MHz with a Transmission Time Interval (TTI) of lms.

In other words, considering such a scenario, it is desirable to avoid the use of an additional uplink message in an initial uplink message in order to reduce a delay in the state transition of a UE. The initial uplink message may be, for example, the radio resource connection request message mentioned with reference to FIG. 1.

In other words, mostly for transition from LTE IDLE to LTE ACTIVE, it is desirable to limit the size of the initial uplink message to 100 bits.

When the RRC state transition of a UE is initiated by a service request for uplink/downlink data transmission (UL/DL data), information as shown in Table 1 can be contained in the radio resource connection request message.

[Table 1]

When state transition is initiated due a 'Tracking Area update' the following information elements are contained in the radio resource connection request message.

[Table 2]

The LTE system is discussing about reduction of the size of integrity check information from among the information elements and reduction of the size of the initial uplink message by omitting initial UE AS capabilities. This method may reduce a size of about 30 bits. Although this result is close to an assumed limit of 100 bits, further reduction is still required.

In relation to the initial radio access procedure of the LTE system, the present invention newly defines a TA code and a method of a PLMN ID, thereby significantly contributing to reduction of the size of the initial uplink message. The TA code and the PLMN ID are information that allows reduction of the size of the initial uplink message according to an exemplary embodiment of the present invention. The TA code and the PLMN IDs suggested in the LTE system are partially similar to a location area code and PLMN IDs that are specific IDs of a legacy mobile communication system.

The location area code and the PLMN ID of the legacy system will be defied in brief.

* Location Area ID

This identifies uniquely a location area for a GSM-MAP type PLMN as below.

[Table 3]

* PLMN ID

This information element identifies a Public Land Mobile Network (PLMN) for a GSM-MAP type PLMN as below. Table 4

* Further information about related IDs

This section briefly discusses IDs that are newly suggested in association with optimization of the size of the initial uplink message, which is a solution suggested by the present invention.

* TA ID

In order to resolve potential contentions in an initial access procedure, a UE needs to include a globally unique UE ID in an initial uplink message.

In particular, most UEs in LTE IDLE are assumed to have stored on a Subscriber Identity Module (SIM) a temporary ID that the network has previously assigned, i.e., Packet-Temporary Mobile Subscriber Identifier (P-TMSI). Since the temporary ID is unique within a TA, the UE also has to identify the TA in which it was assigned when using the P-TMSI. The TA-ID is composed of a TA code that uniquely identifies a TA within a PLMN, and a PLMN ID.

* PLMN ID

When the UE uses 'P-TMSF, the PLMN ID of the TA where this temporal ID was assigned is needed to provide a globally unique UE ID.

In the case of network sharing, a cell may broadcast multiple PLMN IDs out of which the UE selects one. In this case, the UE will have to indicate the selected PLMN to enable an eNB to route a connection request to an appropriate CN node.

Hereinafter, broadcasting of concerned IDs in a UMTS system will be described. Generally, in the UMTS system, PLMN IDs are contained in a master information block to be broadcasted as in Table 5 A and Table 5B.

[Table 5A]

Table 5B

A multiple PLMN list will now be described in more detail.

* Multiple PLMN list

This information element identifies multiple Public Land Mobile Networks (for a PLMN of a GSM-MAP type) of a cell in a shared network as below.

This information element identifies the multiple Public Land Mobile Networks (for a GSM-MAP type of PLMN) of a cell in a shared network.

[Table 6]

As mentioned above, in the UMTS system, a single Location Area Code (LAC) is signaled even when network sharing, i.e., multiple PLMN IDs, is used. This LAC is contained in a system information block type 1 as follows.

* System information block type 1

The system information block type 1 contains NAS system information as well as UE timers and counters to be used in an idle mode and a connection mode. [Table 7]

Hereinafter, GSM-MAP NAS system information will be described in detail.

* NAS system information (GSM-MAP)

This information element contains system information that belongs to a non-access stratum for a PLMN of a GSM-MAP type. This information is transparent to RRC. It may contain either information specific to one CN domain (CS or PS) or information common for both CN domains.

Considering such a scenario, size reduction of UE and PLMN' s IDs within the initial uplink message according to an exemplary embodiment of the present invention can be implemented by a message structure and a procedure to be described below.

FIG. 3 illustrates an initial uplink message transmission/reception procedure that is newly suggested according to an exemplary embodiment of the present invention. In other words an initial uplink message whose size is reduced according to the subject of the present invention is transmitted and received.

Referring to FIG. 3, in particular, an L3 message including a combination of AS and NAS information defined according to the present invention, i.e., radio resource connection request messages in steps 345 and 350 of FIG. 3 can be transmitted. In other words, a signaling procedure illustrated in FIG. 3 is optimized by reducing the size of a concerned message.

In step 330, a UE 300 has yet not initiated an initial access procedure and acquires a portion of system information broadcasted in a cell the UE 300 has selected. The system information includes one PLMN ID or, in the case of network sharing, more PLMN IDs and NAS-system information that carries a TA code.

A procedure of an LTE/SAE system that is a next-generation mobile communication system according to the present invention may be partially similar to that of a UMTS system, but the structures of actually used messages are independent of each other. For example, the LTE/SAE system may broadcast a plurality of TA codes.

In this regard, Table 9 and Table 10 illustrate examples of system information that can be transmitted in step 330 according to the present invention. Table 9 illustrates a structure of the system information when the system information is transmitted in the form of a master information block and Table 10 illustrates a structure of the system information as a system information block type l.

[Table 9]

In step 335, the UE 300 transmits a random access preamble message to an eNB 310.

In step 340, upon detection of the random access preamble message, the eNB 310 transmits a random access response message to the UE 300 to respond to the random access preamble message. The random access response message may contain, for example, timing advance, scheduling grant (allowing the UE 300 to transmit a first uplink message), and cell specific temporary ID (C-RNTI).

Upon receipt of the random access response message from the eNB 310 in step 340, the UE 300 transmits a radio resource connection request message, i.e., a first uplink L3 message, to the eNB 310 in step 345.

In most transitions from LTE IDLE to LTE ACTIVE, the UE 300 performs the following operations. When a PLMN ID and/or a TA code to be included in the radio resource connection request to be transmitted correspond with one of corresponding IDs that are broadcasted in a cell, i.e., acquired by the UE 300 in step 330, the UE 300 does not include the full ID in the radio resource connection request message. Instead, the UE 300 performs the following operations.

* UE 's operations

1. When a cell in which the UE 300 sends a radio resource connection request message broadcasts a single corresponding ID,

1.1 When an ID to be signaled is identical to a broadcasted value, i.e., a broadcasted value is applied as a mandatory default value, the UE 300 omits the ID.

1.2 Otherwise, the UE 300 signals a message including the full ID.

2. When a cell in which the UE 300 initiates an initial uplink message broadcasts a plurality of corresponding IDs,

2.1 If an ID to be signaled is identical to one of values that are broadcasted, the UE 300 includes an index, i.e., a pointer to a matching ID.

2.2 Otherwise, the UE 300 signals a message including the full ID.

A message structure suggested in the present invention in relation to the operations of the UE 300 is shown below.

[Table 11]

A mandatory default (MD) value implies that no value is signaled when a value to be indicated is equal to a default value.

The message structure according to an exemplary embodiment of the present invention, i.e., a message including the above-described IEs can reduce the size of an initial message by 30 - 34 bits. In other words, the size of a PLMN ID is 20 bits, whereas the size of a TA code may be 16 bits. In other words, according to an exemplary embodiment of the present invention, by further reducing the size of an initial uplink message by 30 - 36 bits, a requirement for a limited message size can be sufficiently satisfied.

In step 350, the eNB 310 transmits the radio resource connection request message to an MME 320. The radio resource connection request message can be transmitted by including only some of IEs.

When the radio resource connection request message includes a size- optimized version of the PLMN ID or the TA code, the eNB 310 has to convert the PLMN ID or the TA code into a full version thereof before transmitting the radio resource connection request message to the MME 320.

In step 355, the MME 320 transmits a radio resource connection response message to the eNB 310.

In step 360, the eNB 310 transmits the radio resource connection response message to the UE 300.

Example

In the following description, system information broadcasted in a cell according to an exemplary embodiment of the present invention includes 4 PLMN IDs and a single TA code. In this case, a master information block can be configured as in Table 12 and a system information block type 1 can be configured as in Table 13.

[Table 12]

As in this example, a PLMN ID 'P-A' the UE 300 indicates in the radio resource connection request message is the same as the first entry of a list of PLMN IDs included in the master information block. Thus, the UE 300 selects a 'Same as MIB entry' value of a CHOICE PLMN ID type and sets it to a value of ' T.

In addition, a TA code 'T-A' the UE 300 indicates in the radio resource connection request message is the same as a value of a TA code included in the system information block type 1. Since this value is a default value, the UE 300 does not need to signal the actual value.

Thus, the UE 300 does not have to include the full PLMN IDs in the radio resource connection request message, thereby reducing the size of the initial uplink message. For the TA code, the UE 300 does not have to separately signal a corresponding value, thereby reducing the size of the initial uplink message.

Applicability

In the following description, a signaling procedure of a next-generation mobile communication system for transmitting and receiving the initial uplink message will be discussed. Concerned IDs according to an exemplary embodiment of the present invention are to be included in the initial uplink message, provided that a UE is required to update the contents of the message when it needs to re-transmit the message in another cell. This assumption is also applied to a UE in a UMTS system. In the following description, cell re- selection and a timer operation of the UE will be defined in brief.

* Cell re-selection. T300 or T318 timeout

If a UE has not yet received an RRC CONNECTION SETUP response message having the value of an IE "initial UE ID" that is equal to the value of the variable INITIAL UE IDENTITY and cell re-selection or expiry of timer T300 or T318 occurs, the UE checks the value of a counter V300. If V300 is equal to or smaller than preset N300, the UE checks if cell re-selection occurs and sets CFN in relation to SFN of a current cell. The UE sets the RRC CONNECTION REQUEST message. At this time, the UE maps an access class to an access service class. When accessing a Random Access Channel (RACH), the UE uses a given access service class. The UE transmits a new RRC CONNECTION REQUEST message to lower layers for transmission on an uplink Common Control Channel (CCCH). The UE operates the counter V300 and restarts the timer T300 when an MAC layer indicates success or failure to transmit the RRC CONNECTION REQUEST message.

A visiting/roaming UE that has stored a 'P-TMSP on an SIM will apply this as an initial ID. The roaming UE will not reuse the IMSI due to the ID confidentiality of the UE. For visiting UEs, the connection request may not be routed solely based on Network Routing Information (NRI), i.e., a TMSI of 14 - 23 bits.

Consequently, a UE roaming into a shared network may have to indicate both a PLMN ID associated with the P-TMSI stored in the SIM and a PLMN ID corresponding to a selected PLMN. In such a scenario, size optimization for the uplink message according to the present invention can be used.

Even when the IMSI is used as an initial ID in the present invention, the desirable size of the initial uplink message may not be 100 bits because the IMSI is larger than the P-TMSI. In this case, the IMSI is assumed to be used as the initial ID only in a limited number of cases.

Applicability of the present invention to legacy systems The following respects have to be considered for legacy networks, e.g., existing UMTS systems.

1. In legacy networks, AS and NAS procedures used in transition from UE IDLE to UE CONNECTED are performed sequentially. Thus, the initial uplink message includes only AS information. When these networks are designed, less stringent delay requirements may be applied.

2. The size limitation of the initial uplink message is 168 bits in R99 UMTS networks and 238 bits from REL-6 onwards.

In principle, message optimization suggested according to an exemplary embodiment of the present invention can be equally applied to an RRC CONNECTION REQUEST message of a UMTS system. However, message optimization suggested according to an exemplary embodiment of the present invention cannot be used for a PLMN ID included in an INITIAL DIRECT TRANSFER message. This is because the INITIAL DIRECT TRANSFER message can be received in a cell other than one the UE had selected when preparing the message.

When cell re-selection occurs, the UE will prepare a new RRC CONNECTION REQUEST message. As mentioned above, in the case of cell re-selection, a situation in legacy networks, e.g., a UMTS, is different. Thus, in this case, the proposed solution is assumed not to be applicable to legacy networks.

While the present invention has been shown and described with reference to an exemplary embodiment thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention.

Claims

What is claimed is:

1. A method for reducing a size of an initial uplink message transmitted and received between a mobile terminal and network elements in a mobile communication network system, the method comprising: configuring the initial uplink message by omitting at least one of an identity (ID) indicating a Public Land Mobile Network (PLMN), which will hereinafter be referred to as a PLMN ID, and an ID indicating a Tracking Area (TA), which will hereinafter be referred to as a TA ID, within the initial uplink message; and transmitting and receiving the configured initial uplink message.

2. The method of claim 1, wherein the configuring of the initial uplink message comprises configuring the initial uplink message by omitting at least one of the PLMN ID and the TA ID, if one of a first condition that a network element of a cell in which the mobile terminal that transmits the initial uplink message is located broadcasts a single PLMN ID or a single TA ID, and a second condition that an ID to be signaled by the mobile terminal using the initial uplink message is equal to a value broadcasted in the first condition is satisfied.

3. The method of claim 1, wherein the configuring of the initial uplink message comprises configuring the initial uplink message by omitting at least one of the PLMN ID and the TA ID, if one of a third condition that a network element of a cell in which the mobile terminal that transmits the initial uplink message is located broadcasts a plurality of PLMN IDs or a plurality of TA IDs, and a fourth condition that an ID to be signaled by the mobile terminal using the initial uplink message is equal to at least one of values broadcasted in the third condition is satisfied.

4. The method of claim 3, wherein the mobile terminal transmits the initial uplink message containing a pointer to an ID of a serving cell in which the mobile terminal is located.

5. The method of claim 1, wherein the mobile terminal transmits a radio resource connection request message as the initial uplink message.

6. The method of claim 5, wherein when the network elements send portions of the initial uplink message to a second network element, they include the omitted PLMN ID or TA ID.

7. A mobile terminal for reducing a size of an initial uplink message transmitted and received between a mobile terminal and network elements in a mobile communication network system, wherein the mobile terminal configures the initial uplink message having a reduced size by omitting at least one of an identity (ID) indicating a Public Land Mobile Network (PLMN), which will hereinafter be referred to as a PLMN ID, and an ID indicating a Tracking Area (TA), which will hereinafter be referred to as a TA ID.

8. The mobile terminal of claim 7, wherein the mobile terminal configures the initial uplink message by omitting at least one of the PLMN ID and the TA ID, if one of a first condition that a network element of a cell in which the mobile terminal that transmits the initial uplink message is located broadcasts a single PLMN ID or a single TA ID, and a second condition that an ID to be signaled by the mobile terminal using the initial uplink message is equal to a value broadcasted in the first condition is satisfied.

9. The mobile terminal of claim 7, wherein the mobile terminal configures the initial uplink message by omitting at least one of the PLMN ID and the TA ID, if one of a third condition that a network element of a cell in which the mobile terminal that transmits the initial uplink message is located broadcasts a plurality of PLMN IDs or a plurality of TA IDs, and a fourth condition that an ID to be signaled by the mobile terminal using the initial uplink message is equal to at least one of values broadcasted in the third condition is satisfied.

10. The mobile terminal of claim 9, wherein the mobile terminal is arranged to contain a pointer to an ID of a serving cell in which the mobile terminal is located.

11. The mobile terminal of claim 10, wherein the initial uplink message transmitted by the mobile terminal is a radio resource request message.

12. A network element which receives an initial uplink message from a mobile terminal in a mobile communication network system, wherein the network element receives the initial uplink message having a reduced size by omitting at least one of an identity (ID) indicating a Public Land Mobile Network (PLMN), which will hereinafter be referred to as a PLMN ID, and an ID indicating a Tracking Area (TA), which will hereinafter be referred to as a TA ID.

13. The network element of claim 12, wherein the network element receives the initial uplink message configured by omitting at least one of the PLMN ID and the TA ID, if one of a first condition that a network element of a cell in which the mobile terminal that transmits the initial uplink message is located broadcasts a single PLMN ID or a single TA ID, and a second condition that an ID to be signaled by the mobile terminal using the initial uplink message is equal to a value broadcasted in the first condition is satisfied.

14. The network element of claim 12, wherein the network element receives the initial uplink message configured by omitting at least one of the PLMN ID and the TA ID, if one of a third condition that a network element of a cell in which the mobile terminal that transmits the initial uplink message is located broadcasts a plurality of PLMN IDs or a plurality of TA IDs, and a fourth condition that an ID to be signaled by the mobile terminal using the initial uplink message is equal to at least one of values broadcasted in the third condition is satisfied.

15. The network element of claim 14, wherein the network element receives the initial uplink message containing a pointer to an ID of a serving cell in which the mobile terminal is located.

16. The network element of claim 15, wherein when the network element transmits portions of the initial uplink message to a second network element, the network element includes the omitted PLMN ID or TA ID.