WO2007052968A1

WO2007052968A1 - Method and apparatus for assigning temporary id and scrambling code of ue through initial access procedure in wireless system

Info

Publication number: WO2007052968A1
Application number: PCT/KR2006/004548
Authority: WO
Inventors: Kyeong-In Jeong; Gert Jan Van Lieshout; Youn-Hyoung Heo; Ju-Ho Lee; Soeng-Hun Kim
Original assignee: Samsung Electronics Co., Ltd.
Priority date: 2005-11-02
Filing date: 2006-11-02
Publication date: 2007-05-10
Also published as: KR20070047669A; KR101119247B1

Abstract

A method and apparatus for initial access between a user equipment and a network node in a wireless system are provided. The present invention includes the steps of transmitting, by a first transceiver, a sync request message including a preamble through a physical channel, receiving a response message including a temporary identifier for identifying the first transceiver within a cell from a second transceiver through a physical channel, transmitting scheduling information message including the temporary identifier to the second transceiver, and receiving a message including an allocated radio resource mapped to the temporary identifier from the second transceiver.

Description

DESCRIPTION Invention Title

METHOD AND APPARATUS FOR ASSIGNING TEMPORARY ID AND SCRAMBLING CODE OF UE THROUGH INITIAL ACCESS PROCEDURE IN WIRELESS SYSTEM Technical Field

The present invention generally relates to a wireless system, and more particularly to an apparatus and method for assigning a temporary identifier and a scrambling code of a user equipment (UE) through an initial access procedure between the UE and a network node. Background Art

A universal mobile telecommunication service (UMTS) system is a third-generation asynchronous wireless system using wideband code division multiple access (WCDMA) based on general packet radio services (GPRS) and a global system for mobile communications (GSM) serving as a European wireless system.

Wireless systems use an international mobile subscriber identity (IMSI) to identify the mobility of each user equipment (UE). However, because a size of the IMSI is actually large or increases for security, a radio interface communicates using a temporary identifier (ID) of the UE assigned within a cell in place of the IMSI. This temporary ID of the UE is temporary identification information used in place of the IMSI of each UE. Various types of temporary

IDs of UEs can be provided according to service types supportable in the UEs or control areas for the UEs.

For example, there are a high speed data packet service (HSDPA) radio network temporary ID (H-RTNI) used to support HSDPA, an enhanced uplink dedicated channel (E-DCH) radio network temporary ID (E-RNTI) used to support an E-DCH, a cell radio network temporary ID (C-RNTI) used to transmit signalling or data to UEs within a cell, and so on.

On the other hand, in a code division multiplexing (CDM) system, a scrambling code is a unique code assigned to a UE and is used as a code for allowing a network node to identify the UE upon uplink transmission.

In relation to this, FIG. 1 illustrates a procedure for allocating a temporary ID and a scrambling code of a UE in a 3^rd generation partnership project (3 GPP) system responsible for UMTS standardization.

Referring to FIG. 1, reference numerals 101, 102, and 103 denote a UE, a Node B, and a network node (or radio network controller (RNC)), respectively.

The Node B 102 is a wireless base station for directly participating in communication with the UE 101 and manages cells. The RNC 103 controls multiple Node Bs 102 and controls radio resources.

Steps 111 and 112 are a physical random access channel (PRACH) procedure for random access channel (RACH) message transmission. An RACH is used in UEs for transmitting uplink data without a dedicated channel. The UEs without the dedicated channel are typically in CeIl FACH, Cell_PCH, URA_PCH or idle mode. The PRACH can be defined as a set of radio resources used for an RACH transmission and the radio resources are constructed as follows.

1. A preamble scrambling code: this is one scrambling code mapped to a specific PRACH. For use of the PRACH, a preamble and RACH data to be sent in uplink are scrambled and transmitted with a preamble scrambling code.

2. A signature set: this is orthogonal variable spreading factor (OVSF) codes with a spreading factor (SF) of 16 in which 16 codes per PRACH can be assigned and is used to code a preamble and RACH data. 3. An access slot set: this is constructed with two time slots. A preamble transmission is started at a start point of each access slot.

Further, the UE 101 performs a persistence value test using a persistence value mapped to an associated access service class (ASC). The persistence value is a real number between 0 and 1 and basically indicates the probability of a successful persistence value test. For example, assuming that the persistence value is 0.5, the probability of a successful persistence value test is 50%.

When the persistence value test is successful, the UE 101 transmits a preamble to the Node B 102 in step 111. At this time, the UE 101 randomly selects one of available signatures mapped to the ASC. After the preamble is coded with the selected signature, initial power is set and the coded preamble is transmitted at the set initial power. Since the initial power setting is described in detail in 3GPP technical specification (TS) 25.331, its detailed description is omitted.

In step 112, the Node B 102 transmits an acquisition indication channel (AICH) signal mapped to the preamble transmitted by the UE 101 in step 111. The AICH signal notifies the UE having transmitted the specific signature that the preamble signal has been successfully received and simultaneously indicates the permission of a message transmission on the RACH.

FIG. 1 illustrates the case where the Node B 102 has successfully received the preamble transmitted by the UE 101. Since others for the PRACH procedure is described in detail in 3GPP TS 25.214, their detailed description is omitted.

When receiving acknowledgement (ACK) from the Node B 102 in response to the preamble transmitted through the PRACH procedure in steps 111 and 112, the UE 101 provides the RNC 103 with a radio resource control (RRC)

CONNECTION REQUEST message using an RACH message in step 121.

Herein, the RRC CONNECTION REQUEST message is transmitted from the UE to the RNC to set up an RRC connection in a wireless system.

When the RRC connection setup is completed, the UE and the RNC can set up a signalling radio bearer (SRB). At this time, the UE notifies the RNC of capability information. Information such as a unique ID of the UE and so on can be contained in the RRC CONNECTION REQUEST message. Further, the UE can receive, from the RNC, basic information such as temporary ID information of a C-RNTI to be used in the UE within a cell. Thus, the RNC 103 provides the UE 101 with an RRC CONNECTION

SETUP message serving as a response message to the transmitted message of step 121 in step 122. At this time, the RNC 103 assigns a C-RNTI to be used in the UE 101 within the cell, a scrambling code to be used in the UE, SRB configuration information, and so on. If the UE 101 supports a high-speed packet data service, an H-RNTI can be received.

In step 123, the UE 101 transmits a confirm message to the RNC 103 in response to the message of step 122. At this time, the RNC 103 is notified of capability information of the UE 101 capable of being requested by the RNC

103 in step 122. Message transmissions of steps 121 to 123 are a message flow for setting up the RRC connection and FIG. 1 illustrates an example in which the

RRC connection has been successfully set up.

On the other hand, when the RRC connection has failed in relation to the

RRC CONNECTION REQUEST message of step 121, the RNC 103 can reject a connection related to the message of step 121 by transmitting an RRC CONNECTION REJECT message rather than the RRC CONNECTION SETUP message of step 122. Since others for the RRC connection setup are described in detail in 3GPP TS 25.331, their detailed description is omitted. For reference, the messages of steps 121 to 123 are radio resource control (Layer 3) messages. In step 131, the UE 101 transmits signalling or data to the RNC 103 using a scrambling code of the UE 101 and a temporary ID within the cell of the UE 101 assigned in step 122. For example, the H-RNTI can be assigned in radio bearer setup/reconfiguration for HSDPA radio bearer setup in step 131 rather than step 122. Upon signalling transmission through an HSDPA shared control channel (HS-SCCH) or data transmission through an HSDPA dedicated physical data channel (HS-DPDCH), the notification of signalling or data transmission to the UE 101 is provided using the H-RNTI.

Thus, the UE 101 compares an H-RNTI value included in the signalling or data with an H-RNTI value assigned to the UE 101 and determines whether the transmitted signalling or data is destined for the UE 101. If the H-RNTI values are the same as each other as a comparison result, the signalling or data of step 131 is received.

As described above, the conventional wireless system has a structure in which a temporary ID within a cell and a scrambling code are not transmitted on physical channels of steps 111 and 112, but are transmitted after acquiring sync while considering elements such as power and so on between the UE 101 and the RNC 103 after the procedure of steps 111 and 112 is completed.

In other words, the UE 101 is assigned a temporary ID within a cell or a scrambling code after an RRC connection is set up through the procedure of steps 121 to 123, such that there is a problem in that signalling or data transmission between the UE and the RNC is delayed.

Thus, a need exists for a scheme for efficiently assigning a temporary ID within a cell and a scrambling code that can address the above-described problem of data transmission delay in a wireless system for a high-speed, large- capacity data service.

Disclosure of Invention

Technical Problem

Accordingly, the present invention has been designed to solve the above and other problems occurring in the prior art. Therefore, the present invention provides an apparatus and method for assigning a temporary identifier within a cell of a user equipment (UE) and a scrambling code of the UE through an initial access procedure between the UE and a network node in a wireless system.

Technical Solution

In accordance with an embodiment of the present invention, there is provided a method for initial access between a user equipment and a network node in a wireless system, including the steps of: transmitting, by a first transceiver, a sync message including a preamble; receiving a response message including information mapped to the preamble and a temporary identifier from a second transceiver; and providing the second transceiver with a scheduling request message coded with a code mapped to the temporary identifier or a scheduling request message to which the temporary identifier is added.

In accordance with another embodiment of the present invention, there is provided a method for initial access between a user equipment and a network node in a wireless system, including the steps of: receiving, by a second transceiver, a sync message including a preamble from a first transceiver; providing the first transceiver with a response message including information mapped to the preamble and a temporary identifier; and receiving, from the first transceiver, a scheduling request message coded with a code mapped to the temporary identifier or a scheduling request message to which the temporary identifier is added.

Advantageous Effects

Therefore, the present invention can efficiently and quickly transmit signaling or data for a UE by assigning a temporary identifier within a cell of the UE and a scrambling code of the UE through an initial access procedure. Brief Description of the Drawings

FIG. 1 illustrates a procedure for assigning a temporary ID and a scrambling code of a UE in a 3GPP system;

FIG. 2 illustrates a structure of an evolution wireless system to which the present invention is applied; FIG. 3 illustrates a procedure for assigning a temporary ID and a scrambling code of a UE through an initial access procedure in accordance with a preferred embodiment of the present invention;

FIG. 4 illustrates a structure of a network node in accordance with a preferred embodiment of the present invention; and FIG. 5 illustrates a structure of a UE in accordance with a preferred embodiment of the present invention.

Best Mode for Carrying Out the Invention

Now, operation principles of preferred embodiments of the present invention will be described in detail herein below with reference to the accompanying drawings. In the following description, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention unclear. Further, the terms to be described below are defined according to functions associated with the present invention. The terms can be varied by an intention or practice of a user or operator. Accordingly, term definitions should be determined based on the following description.

As described below, a method proposed in the present invention is not limited to a 3^rd generation partnership project (3 GPP) universal mobile telecommunication service (UMTS) system, and will be described with reference to an example of an evolution system of the 3GPP system currently being discussed in 3GPP. The present invention is applicable to every wireless system to which a base station's scheduling is applied without special modification. Further, the present invention is applicable to a system for supporting an uplink service. Therefore, the present invention proposes a more efficient initial access procedure and a scheme for assigning a temporary identifier (ID) within a cell of a user equipment (UE) and a scrambling code of the UE. Further, the present invention proposes a scheme for minimizing delay of signalling or data transmission between the UE and a network node through a newly proposed initial access procedure.

FIG. 2 illustrates a structure of a 3GPP evolution system to which the present invention is applied.

Referring to FIG. 2, a UE 210 is a terminal and an evolved radio access network (E-RAN) 240 is a network node including a Node B and a radio network controller (RNC) in the 3GPP system. In the E-RAN 240 of the 3GPP system, functions of an evolved Node B (E-Node B) 220 and an evolved RNC

(E-RNC) 230 can be physically separated in different nodes.

An evolved core network (E-CN) 250 is a node in which functions of a serving general packet radio services (GPRS) support node (SGSN) and a gateway GPRS support node (GGSN) of the 3GPP system are integrated into one unit, and is placed between a packet data network (PDN) 260 and the E-

RAN 240. The E-CN 250 assigns an Internet protocol (IP) address to the UE 210 and functions as a gateway for connecting the UE 210 to the PDN 260. In FIG. 3, an initial access procedure of the UE in the newly proposed 3GPP evolution system of FIG. 2 is defined.

FIG. 3 illustrates a procedure for assigning a temporary ID and a scrambling code through an initial access procedure in accordance with a preferred embodiment of the present invention.

Referring to FIG. 3, reference numeral 301 denotes a UE and reference numeral 302 denotes an E-RAN. In step 311, the UE 301 provides the E-RAN

302 with a physical channel sync request (PCSR) message corresponding to an initial physical message for physical channel sync. In step 311, the PCSR message is transmitted on a physical channel.

The PCSR message is transmitted to acquire timing sync or transmission power sync between the UE 301 and the E-RAN 302. At this time, the PCSR message containing a preamble or a random code can be transmitted.

Alternatively, the preamble and the random code can be transmitted together.

If the preamble and the random code are transmitted together, multiple

UEs using the same preamble can be identified by the random code. Thus, congestion between the multiple UEs using the same preamble can be prevented.

In step 312, the E-RAN 302 provides the UE 301 with a PHYSICAL

CHANNEL SYNC RESPONSE message in response to the message of step 311.

When acquiring timing and power syncs with the UE 301, the E-RAN 302 provides the UE 301 with the PHYSICAL CHANNEL SYNC RESPONSE message containing a radio network temporary ID (RNTI) to be used within a cell of the UE 301, for example, a cell RNTI (C-RNTI), and a scrambling code.

Herein, the C-RNTI serving as the temporary ID available within the cell of the

UE 301 can be used as identification information within the cell to identify each

UE for downlink/uplink signalling/data transmission. Further, the E-RAN 302 transmits a response message containing the preamble or random code received in step 311 without modification in order to indicate a specific UE for receiving the message of step 312, i.e., the UE 301.

On the other hand, when timing or power sync with the UE 301 is not acquired, the E-RAN 302 can include and transmit additional information for acquiring the timing or power sync. In this case, information about the temporary ID within the cell of the UE 301 or the scrambling code may not be included. When the additional information for acquiring the timing or power sync is included, the UE 301 having received the response message of step 312 again sets timing or power on the basis of the additional information and retransmits the message of step 311. At this time, the message retransmitted by the UE 301 can be provided using a newly selected preamble or random code without reusing the random code or preamble used in the previous message of step 311.

However, the transmission of the response message of step 312, i.e., the transmission of the response message containing the random code or preamble received in the message of step 311 without modification, can be equally applied to the case where the timing or power sync with the UE 301 is acquired or not acquired.

When determining that the random code or preamble received in the response message of step 312 is the same as that transmitted in step 311, the UE 301 recognizes the message of step 312 as the message transmitted to itself and can continuously perform step 313. On the other hand, when a random code or preamble different from that transmitted in step 311 is received in the message of step 312, the UE 301 determines that the received response message is not its own message and then repeats step 311.

In a method for optimizing the PHYSICAL CHANNEL SYNC RESPONSE message between the E-RAN 302 and the UE 301, the E-RAN 302 can perform step 312 by including only a C-RNTI value. At this time, a scrambling code to be used in the UE 301 is automatically assigned by the given C-RNTI value and an implicit mapping rule. That is, the scrambling code to be used in the UE 301 is automatically assigned by the C-RNTI value transmitted in step 312 and a one-to-one mapping rule. Thus, the scrambling code of the UE 301 does not need to be explicitly assigned in the message of step 312. In this case, there is an advantage in that a size of the response message of step 312 can be reduced.

The implicit mapping rule for the C-RNTI and the scrambling code can be applied by defining one universal rule or can be applied by broadcasting system information within a cell for the mapping rule. When one universal mapping rule is applied, it is applied to hard coding within the UE. Further, when the mapping rule received in the system information is applied, the UE can apply the mapping rule for the C-RNTI and the scrambling code through the system information reception from the E-RAN.

Alternatively, the two methods may be simultaneously applied. That is, if any mapping rule is not included in the system information, the universal mapping rule is applied. If the mapping rule is included in the system information, the mapping rule based on the system information can be first applied.

Use of the C-RNTI and the scrambling code of the UE 301 can be variously applied according to multiple access schemes. In a radio resource interval to which a code division multiple access (CDMA) scheme is applied, signalling or data is coded and transmitted with the assigned scrambling code.

On the other hand, in a radio resource interval to which the CDMA scheme is not applied, signalling or data is transmitted with the C-RNTI.

For example, using a scrambling code implicitly mapped to the C-RNTI assigned in step 312, signalling or data is transmitted on a contention based channel. At this time, use of the CDMA scheme in the radio resource interval should be predefined between the UE and the network node (e.g., the E-RAN) according to rule or should be known to the UE and the network node through signalling. In step 313, the UE 301 makes a scheduling request for signalling or data to be transmitted by providing the E-RAN 302 with a scheduling information (SI) message.

As described above, if the CDMA scheme is applied between the E-

RAN and the UE in the radio resource interval for the SI message transmission of step 313, the SI message is coded and transmitted with a scrambling code mapped to the given C-RNTI value or explicitly indicated by the E-RAN.

Otherwise, the SI message is transmitted using the C-RNTI given in step 312 without modification. At this time, the message of step 313 may not need to be coded. In step 314, the E-RAN 302 gives notification of assigned radio resources in a response message to the SI message of step 313 after assigning the radio resources for signalling or data transmission of the UE 301. Herein, step

314 shows an example to which the CDMA scheme is not applied. That is, information about the radio resources is transmitted using a scrambling code and so on without coding, such that a resource allocation message for a UE is identified using the C-RNTI value given in step 312.

Since the E-RAN 302 can know a C-RNTI mapped to the scrambling code even when a message coded with the scrambling code is transmitted in step 313, there is no problem in transmitting a response message using the C-RNTI in step 314.

Then, in step 321, signalling or data is transmitted using the C-RNTI assigned in step 312 between the UE 301 and the E-RAN 302 corresponding to the network node. At this time, the C-RNTI indicates a UE for which the signalling or data is transmitted. If there is a radio resource interval to which the CDMA scheme is applied also in step 321, signalling or data is coded and transmitted with a scrambling code implicitly mapped to the C-RNTI received in step 312.

The scrambling code can be used to transmit an aperiodic message such as an SI message for an aperiodic scheduling request in uplink, a cell update message (for notifying when a cell is changed), a measurement report message (for reporting radio strength of a current cell or adjacent cell), or so on. Herein, a message range to which the scrambling code is applied is for illustrative purpose only, and is not limited in the present invention. A radio resource interval to which the CDMA scheme is applied should be predefined by an implicit rule or signalling between the E-RAN 302 and the UE 301. Herein, the signalling can include all of broadcast system information, signalling through a common control channel, and dedicated signalling transmitted only to a specific UE.

In FIG. 3, if the message of step 313 containing the C-RNTI or using a scrambling code mapped to the C-RNTI is not transmitted from the UE 301 even when the E-RAN 302 assigns the C-RNTI value to be used in the UE 301 through the message of step 312, an operation for continuously maintaining the C-RNTI of the UE 301 assigned by the E-RAN may lead to a radio resource waste. This is because the number of C-RNTIs or scrambling codes that the E- RAN 302 can assign within a cell is limited. This scenario may occur because of many reasons when the UE 301 moves to another cell while performing steps 311 and 312 or the UE 301 suddenly enters a shading area.

Therefore, when the E-RAN 302 assigns the C-RNTI value in the message of step 312 after receiving the message of step 311 in the present invention, a specific timer operates. If the message of step 313 is not received until the timer expires, the E-RAN determines that the C-RNTI value assigned for the UE 301 is no longer valid and assigns the C-RNTI to another UE without continuously maintaining/occupying the C-RNTI.

A value of the timer should be known to both the E-RAN and the UE through an implicit rule or signalling. If the UE has to transmit the message of step 313 after the timer expires even though the C-RNTI has been successfully received in step 312, it has to again receive a new C-RNTI by repeating the steps from step 311 in place of the message transmission of step 313. Further, if the timer value is signalled, it can be signalled to the UE through system information broadcast within the cell or through a common control channel of the message of step 312 or dedicated channel signalling.

At this time, the timer value can use the number of valid transmission time intervals (TTIs) until the message of step 313 is transmitted using the C- RNTI, a system frame number, an absolute time value, or so on. FIG. 3 illustrates the case where the message of step 313 is transmitted before the time expires after the UE 301 receives the message of step 312.

The timer for checking the validity of the C-RNTI can be used to check a reception time of the message of step 313 and also can be used while signalling or data is transmitted in step 321. For example, when the signalling or data transmission (step 321) of the specific UE 301 does not occur for a specific long time, a radio resource waste can be caused as described above. That is, when considering that the C-RNTI or scrambling code is the limited radio resource, it is not preferable that the UE 301 occupies the radio source even though the signalling or data transmission does not occur for the specific long time. Therefore, the above-described type of timer operates also during the signalling or data transmission of step 321 in the present invention. Only the timer applied to step 321 may have a different value from a timer applied between steps 312 and 313 even when they are used for the same purpose.

For example, the timer applied between steps 312 and 313 can use a short timer value and the timer applied during the signalling or data transmission in step 321 can use a long timer value. The timer applied during the signalling or data transmission should be also predefined between the UE 301 and the E-RAN 302 by the signalling or implicit rule.

Hereinafter, the timer applied between steps 312 and 313 is referred to as the timer 1 and the timer applied during the signalling or data transmission of step 321 is referred to as the timer 2. The timer 2 is newly updated whenever the signalling or data transmission for the UE 301 occurs, which is different from the timer 1 (i.e., the timer 2 is updated and restarted whenever the signalling or data transmission occurs before the timer 2 expires). Only an exact update time or condition of the timer can be newly updated on the basis of a signalling or data transmission time or on the basis of a time at which acknowledgment (ACK) for the signalling or data transmission is received from a peer node. The update condition or time of the timer can be applied in many methods.

When the timer 2 expires like the timer 1, the E-RAN determines that the C-RNTI value assigned for the UE 301 is no longer valid and can assign the C-RNTI to be used in another UE. The UE 301 determines that the C-RNTI is no longer valid and should receive a new C-RNTI by repeating steps 311 and 312 if the signalling or data transmission is required thereafter.

On the other hand, steps 331 and 332 are a procedure for transmitting a PCSR in event occurrence when detecting that the PCSR is periodically transmitted while the C-RNTI is valid after the C-RNTI is initially received in steps 311 and 312 and the UE enters an out-of-service area. That is, the UE 301 can periodically use PCSR messages of steps 331 and 332 to continuously acquire power or timing sync with the E-RAN 302 even when the power or timing sync has been acquired in steps 311 and 312. Further, the UE can use the PCSR messages of steps 331 and 332 for resync when determining that the sync has been missed.

No problem occurs if a new C-RNTI is received in step 312 of steps 311 and 312 when the UE 301 does not have a valid C-RNTI in steps 331 and 332. However, if the UE 301 has a valid C-RNTI upon transmission of step 331, an operation for receiving a new C-RNTI assigned in step 332 leads to signalling overhead in which the C-RNTI is signalled in step 332. This is because the new C-RNTI does not need to be assigned when the UE 301 already has the valid C- RNTI.

Therefore, if the UE 301 has the valid C-RNTI or scrambling code assigned to itself when the PCSR transmission is performed for resync or for a periodic PCSR rather than an initial PCSR, the UE 301 sets and transmits a C- RNTI indication in the PCSR message as in step 331. The C-RNTI indication indicates that the C-RNTI does not need to be newly assigned since the UE 301 already has the valid C-RNTI and scrambling code. Use of the C-RNTI indication can be variously applied as follows. Example 1 : Interpretation of Presence/Absence of C-RNTI Indication The C-RNTI indication (or the C-RNTI in step 331) is present: the UE has the valid C-RNTI and scrambling code.

The C-RNTI indication (or the C-RNTI in step 311) is absent: the UE does not have the valid C-RNTI and scrambling code.

Example 2: Interpretation of True/False Value Set in C-RNTI Indication The C-RNTI indication is set to a true value (in step 331): the UE has the valid C-RNTI and scrambling code. The C-RNTI indication is set to a false value (in step 311): the UE does not have the valid C-RNTI and scrambling code.

Example 3: Use of different preamble sets when C-RNTI allocation is required and not required A preamble set to be used in the PCSR when the UE has the valid C-

RNTI and scrambling code is defined, which is different from that when the UE does not have the valid C-RNTI and scrambling code. A preamble is selected and used from the preamble set mapped to each case.

When the example 1 is applied among the examples of the C-RNTI indication in FIG. 3, the C-RNTI indication is not present in step 311. The C- RNTI indication is present in step 331 if the UE 301 has the valid C-RNTI and scrambling code.

When the example 2 is applied, the C-RNTI indication is present and set to the false value in step 311. The C-RNTI indication is present and set to the true value in step 331 if the UE has the valid C-RNTI and scrambling code.

When the example 3 is applied, a preamble is selected from a preamble set to be used when the UE does not have the valid C-RNTI and scrambling code and the selected preamble is applied to step 311. A preamble is selected from a preamble set to be used when the UE has the valid C-RNTI and scrambling code and the selected preamble is applied to step 331. At this time, the E-RAN 302 can detect the presence/absence of a new C-RNTI allocated to the UE by interpreting the preamble used for the PCSR.

If the interpreted PCSR preamble is included in the preamble set to be used when the UE does not have the valid C-RNTI and scrambling code, the E- RAN 302 includes and transmits a new C-RNTI in a response message to the PCSR. If the interpreted PCSR preamble is included in the preamble set to be used when the UE has the valid C-RNTI and scrambling code, the E-RAN 302 does not include a new C-RNTI in a response message to the PCSR and transmits the response message without the new C-RNTI.

To apply the example 3, the two types of preamble sets should be predefined between the UE and the E-RAN by an implicit rule or signalling. The signalling can use broadcast system information, signalling through a common control channel, or dedicated signalling. FIG. 3 illustrates the case where an C-RNTI indication is present when the example 1 is applied to step 331, the E-RAN 302 does not assign a new C- RNTI for the UE 301, and a C-RNTI value is not included in the response message of step 332 to the message of step 331. The above-described operation can be performed also in the examples 2 and 3. FIG. 4 illustrates a structure of the network node (or E-RAN) in accordance with a preferred embodiment of the present invention.

In FIGS. 4 and 5, it is assumed that the UE indicates new C-RNTI allocation in the PCSR in the example 3 (by separately using a preamble set to be used in the PCSR when a new C-RNTI is requested (hereinafter, referred to as a preamble set 1) and a preamble set to be used in the PCSR when a valid C- RNTI and scrambling code are already possessed (hereinafter, referred to as a preamble set 2).

A scrambling to be used in the UE is not explicitly assigned in a response message to the PCSR in FIGS. 4 and 5, and FIGS. 4 and 5 are exemplary block diagrams under assumption that the UE performs a method for acquiring an associated scrambling code using an implicit one-to-one mapping rule related to a C-RNTI given by the response message to the PCSR. Herein, devices illustrated in FIGS. 4 and 5 are logical functional blocks that those skilled in the art can design in software or hardware. The devices of the UE or network node are not limited to the illustrated functional blocks, and can be integrated and constructed with one or more blocks.

Referring to FIG. 4, a PCSR reception section 401 is a block for receiving a PCSR message from the UE. That is, the PCSR message transmitted from the UE is acquired through the PCSR reception section 401. A timing and power control section 411 controls timing and power for timing and power sync acquisition of the UE through the PCSR message received and delivered by the PCSR reception section 401.

A PCSR response transmission section 421 receives timing and power control information from the timing and power control section 411 and then actually includes and transmits the timing and power control information in the PCSR response message.

A preamble extraction section 431 extracts a preamble used in the PCSR from the PCSR message received from the PCSR reception section 401. The preamble extracted by the preamble extraction section 431 is input to an available preamble set determination section 441. The available preamble set determination section 441 determines whether the preamble of the preamble extraction section 431 is included in a preamble set 1 or 2. That is, the available preamble set determination section 441 determines whether the detected preamble belongs to the preamble set to be used in the PCSR when new C-RNTI allocation is requested or the preamble set to be used in the PCSR when a valid C-RNTI and scrambling code are possessed.

When the available preamble set determination section 441 detects a type of used preamble set, a C-RNTI/scrambling code allocation/management section 451 assigns the new C-RNTI in the PCSR response message. The C- RNTI/scrambling code allocation/management section 451 further manages the validity of the C-RNTI or scrambling code using the timers 1 and 2 as described with reference to FIG. 3.

When the timing and power control section 411 outputs the timing and power control information and the C-RNTI/scrambling code allocation/management section 451 allocates the new C-RNTI, they are included in the response message to the PCSR message received from the PCSR reception section 401 and are transmitted to the UE through a PCSR response transmission section 421 in the form of the PCSR response message.

A signalling/data transmission/reception section 461 is a block for transmitting signalling or data to or receiving signalling or data from the UE when the PCSR procedure is not performed, and processes signalling or data received from or to be transmitted to the UE. At this time, a C-RNTI/scrambling code extraction section 471 extracts a C-RNTI or scrambling code used in a received or transmitted message or signalling. For example, in order to identify a UE from which signalling is received upon reception of the signalling, a C-RNTI value included in the signalling is extracted. If the signalling is received in a radio resource interval to which the CDMA scheme is applied, a type of coded scrambling code is extracted. This is equally applied upon reception and transmission. When signalling is transmitted to a specific UE, a C-RNTI for the UE is inserted into the signalling.

The C-RNTI/scrambling code extraction section 471 can detect a C-

RNTI or scrambling code mapped to a specific UE by exchanging a message with the C-RNTI/scrambling code allocation/management section 451. Also the validity of the C-RNTI and scrambling code can be detected by exchanging a message with the C-RNTI/scrambling code allocation/management section 451.

FIG. 5 illustrates a structure of a UE in accordance with a preferred embodiment of the present invention.

Referring to FIG. 5, a PCSR transmission section 501 is a block for transmitting a PCSR to an E-RAN. The PCSR transmission section 501 provides a network node with a preamble, to be used in a PCSR message, selected from a proper preamble set in a preamble setting/selection section 511 in a state in which timing and power are set by exchanging a message with a timing and power control section 541.

A C-RNTI/scrambling code management section 521 manages a C- RNTI and a scrambling code held in the UE, and further manages the validity of the C-RNTI and scrambling code using the timers 1 and 2 as described with reference to FIG. 3.

The preamble setting/selection section 511 receives management information from the C-RNTI/scrambling code management section 521 and then selects a specific preamble to be used in the PCSR message from a proper preamble set of the preamble sets 1 and 2.

For example, when a valid C-RNTI and scrambling code are absent in the C-RNTI/scrambling code management section 521, the preamble setting/selection section 511 selects a preamble to be used in the PCSR from the preamble set 1.

A PCSR response reception section 531 is a block for receiving a response message to the PCSR from the E-RAN. The PCSR response reception section 531 compares a preamble extracted from the received PCSR response message with a preamble setting value used in the PCSR of the preamble setting/selection section 511 and determines whether the PCSR response message has been transmitted for the UE.

If the preamble used in the PCSR of the preamble setting/selection section 511 is equally included in the PCSR response message received by the PCSR response reception section 531 and timing and power control information is included in the PCSR response message, the timing and power control information is sent to the timing and power control section 541. If C-RNTI information is included, it is extracted by a C-RNTI/scrambling code extraction section 551.

The C-RNTI/scrambling code extraction section 551 further extracts a one-to-one mapped scrambling code from the extracted C-RNTI information. The C-RNTI and scrambling code extracted by the C-RNTI/scrambling code extraction section 551 are sent to the C-RNTI/scrambling code management section 521. The C-RNTI/scrambling code management section 521 manages the C-RNTI and scrambling code. Reference numeral 561 denotes a signalling/data transmission/reception section communicating with the E-RAN when the PCSR procedure is not performed. The signalling/data transmission/reception section 561 receives signalling or data from and transmits signalling or data to the E-RAN. At this time, the C-RNTI/scrambling code management section 521 inserts or extracts a C-RNTI or scrambling code used in a transmitted and received message or signalling.

For example, when signalling is received from the E-RAN, a C-RNTI value included in the signalling is extracted and compared with a valid C-RNTI managed in a UE in order to determine whether the signalling is destined for the UE. If the C-RNTI values are the same as each other, the signalling is determined to be destined for the UE and the signalling is continuously processed.

If the UE transmits signalling or data in a radio resource interval to which a CDMA scheme is applied, the signalling or data is coded and transmitted with a valid scrambling code kept in the C-RNTI/scrambling code management section 521. If the UE transmits signalling or data in a radio resource interval to which no CDMA scheme is applied, a valid C-RNTI kept in the C-RNTI/scrambling code management section 521 is inserted into the signalling or data. Although the concrete embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions, and substitutions are possible, without departing from the scope of the present invention. Therefore, the present invention is not limited to the above-described embodiments, but is defined by the following claims, along with their full scope of equivalents.

Claims

1. A method for initial access between a first transceiver and a second transceiver in a wireless system, comprising the steps of: transmitting, by the first transceiver, a sync request message comprising a preamble through a physical channel; receiving a response message comprising a temporary identifier for identifying the first transceiver within a cell from the second transceiver through a physical channel; transmitting scheduling information message comprising the temporary identifier to the second transceiver; and receiving a message comprising an allocated radio resource mapped to the temporary identifier from the second transceiver.

2. The initial access method of claim 1, further comprising the step of: transmitting, by the first transceiver, a scheduling information message scrambled with a code mapped to the temporary identifier to the second transceiver.

3. The initial access method of claim 2, further comprising the step of: receiving, by the first transceiver, a mapping relation between the temporary identifier and the scrambling code through system information.

4. The initial access method of claim 1, further comprising the step of: operating, by the second transceiver, a first timer for checking validity of the temporary identifier after transmitting the response message comprising the temporary identifier.

5. The initial access method of claim 4, further comprising the step of: operating, by the second transceiver, a second timer having a time length different from that of the first timer for checking the validity of the temporary identifier after transmitting the message comprising the allocated radio resource.

6. The initial access method of claim 5, further comprising the step of: reallocating and transmitting, by the second transceiver, the temporary identifier to a different first transceiver when a scheduling request message is not received from the first transceiver during a time set at the first timer.

7. The initial access method of claim 5, further comprising the step of: updating, by the second transceiver, the second timer when data is transmitted from the first transceiver using the allocated radio resource.

8. The initial access method of claim 1, wherein the sync request message further comprises a random code for distinguishing the first transceiver from other first transceivers using the same preamble as the first transceiver.

9. The initial access method of claim 1, wherein the response message comprises the same preamble as the sync request message.

10. The initial access method of claim 8, wherein the response message further comprises the same random code as the sync request message.

11. The initial access method of claim 1, further comprising the step of: transmitting, by the first transceiver, data using the temporary identifier in the allocated resource to the second transceiver.

12. The initial access method of claim 1, further comprising the step of: transmitting, by the first transceiver, the sync request message to the second transceiver through a physical channel.

13. The initial access method of claim 12, further comprising the step of: periodically transmitting, by the first transceiver, a sync request message comprising identification information for indicating presence of the temporary identifier to the second transceiver through a physical channel.

14. The initial access method of claim 1, further comprising the step of: transmitting, by the first transceiver, a sync request message comprising identification information for indicating validity of the temporary identifier to the second transceiver through a physical channel.

15. The initial access method of claim 14, further comprising the step of: periodically transmitting, by the first transceiver, the sync request message to the second transceiver through a physical channel.

16. The initial access method of claim 1, further comprising the steps of: selecting, by the first transceiver, a preamble from a preamble set based on a valid temporary identifier distinguished from a previous preamble set based on an invalid temporary identifier and transmitting a sync request message comprising identification information for indicating a change of the temporary identifier based on the selected preamble to the second transceiver through a physical channel.

17. The initial access method of claim 16, further comprising the step of: periodically transmitting, by the first transceiver, the sync request message to the second transceiver through a physical channel.

18. The initial access method of claim 17, further comprising the steps of: determining, by the second transceiver, whether the temporary identifier is valid using identification information about the temporary identifier and transmitting a response message comprising the same preamble as the sync request message to the first transceiver.

19. A user equipment for performing initial access in a wireless system, comprising: a preamble selection section for selecting a specific preamble to transmit a sync request message; a detection section for extracting a temporary identifier for identifying the user equipment within a cell from a response message that a network node transmits in response to the sync request message; and a management section for managing validity of the temporary identifier.

20. The user equipment of claim 19, wherein the preamble selection section further selects a specific preamble from a different preamble set distinguished from a set comprising a previously selected preamble on a basis of a result of a validity determination by the management section.

21. The user equipment of claim 19, wherein the management section further manages the temporary identifier and a scrambling code having a mapping relation with the temporary identifier.

22. The user equipment of claim 19, further comprising: a timing control section for determining whether the temporary identifier is valid during a time set at a first timer and providing the management section with a determination result.

23. The user equipment of claim 22, wherein the timing control section further determines whether a temporary identifier extracted from a message comprising a radio resource allocated from the network node is valid during a time set at a second timer.

24. The user equipment of claim 19, further comprising: a response reception section for determining whether the preamble selected from the preamble selection section is identical with a preamble detected from the response message.

25. A network node for performing initial access in a wireless system, comprising: a preamble extraction section for receiving a sync request message from a user equipment and detecting a preamble from the received sync request message; a determination section for detecting presence of a valid temporary identifier of the user equipment using the detected preamble and determining a preamble set to which the preamble belongs; a code allocation management section for allocating a temporary identifier on a basis of a determination result; and a code extraction section for identifying the user equipment by detecting the allocated temporary identifier from a transmitted uplink message.

26. The network node of claim 25, further comprising: a response transmission section for transmitting a response message comprising the allocated temporary identifier to the user equipment.

27. The network node of claim 25, further comprising: a management section for determining validity of the allocated temporary identifier using a time set at a timer.