WO2009035243A2

WO2009035243A2 - Apparatus and method for determining radio access technology (rat) for high-speed data service in a mobile communication system

Info

Publication number: WO2009035243A2
Application number: PCT/KR2008/005304
Authority: WO
Inventors: Ki-Hyun Do; Dong-Jun Kang
Original assignee: Samsung Electronics Co., Ltd.
Priority date: 2007-09-10
Filing date: 2008-09-09
Publication date: 2009-03-19
Also published as: KR20090026442A; WO2009035243A3; KR101429091B1

Abstract

An apparatus and a method for determining a Radio Access Technology (RAT) supporting a high-speed data service in a mobile communication system are provided. The method includes periodically broadcasting, at a Radio Network Controller (RNC), system information which comprises an RAT list and an RAT access threshold; examining, at a User Equipment (UE), neighbor RATs supporting the high-speed data service using the RAT list; and determining an RAT to connect a Mobile Origination (MO) call by comparing an energy to noise ratio (Ec/N0) of the examined RAT signal with the RAT access threshold.

Description

APPARATUS AND METHOD FOR DETERMINING RADIO

ACCESS TECHNOLOGY (RAT) FOR HIGH-SPEED DATA

SERVICE IN A MOBILE COMMUNICATION SYSTEM

Technical Field

[1] The present invention relates generally to an apparatus and a method for determining a Radio Access Technology (RAT) to support a high-speed data service in a mobile communication system. More particularly, the present invention relates to an apparatus and a method for determining an RAT to support a high-speed data service using a threshold for a network access in a Universal Mobile Telecommunication Service (UMTS) system. Background Art

[2] Recently, in response to diverse communication systems using different communication schemes, methods for compatibility between the different communication systems are under development. For example, when systems using different communication schemes lie adjacent to each other, researches are conducted on a method for a User Equipment (UE) to reselect a cell and to hand over from a current servicing system to a system of the different communication scheme and the different frequency according to its conditions. The cell reselection and the handover can be classified into an Inter-frequency method and an Inter-Radio Access Technologies (RAT) method.

[3] According to the cell reselection of the Inter-RAT in a conventional Universal

Mobile Telecommunication Service (UMTS) system, the UE determines a measurement threshold for the Inter-RAT cell reselection by referring to System Information Block (SIB) received over a network in an idle mode, and compares an energy to noise ratio (EJNo) of a Common Pilot Channel (CPICH) of the current cell with the measurement threshold. According to a result of the comparison, the UE reselects a cell of the different RAT by measuring a signal of the different RAT. When the E_c/No of the current cell is less than or equal to the measurement threshold as shown in FIG. 1, the UE measures the signal of the different RAT. When the E_c/N₀ of the current cell is greater than the measurement threshold, the UE does not measure the signal of the different RAT. Herein, whether to measure the signal of the different RAT using the Inter-RAT measurement threshold can be expressed as Equation (1).

[4] MathFigure 1

[Math.l]

Qqualmeas - Qqualmin > S searchRATm • • •(!) [5] In Equation (1), Qqualmeas denotes a cell quality of the received signal and is represented using E_c/N₀ [dB] of the CPICH. SsearchRATm denotes a threshold for determining whether to measure the signal in the cell of RAT 'm' ; that is, denotes the Inter-RAT measurement threshold. SsearchRATm ranges -32 ~ +20[dB]. Qqualmin denotes a minimum quality level required in the cell and ranges -24 ~ 0[dB].

[6] In the conventional UMTS system, the handover method of the Inter-RAT is performed as shown in FIG. 2.

[7] FIG. 2 illustrates signal flows for the Inter-RAT handover of the UE in the conventional UMTS system.

[8] In FIG. 2, upon receiving a high-speed data service call request from a user, the UE

200 performs an RRC connection by transmitting and receiving an RRC connection request message 210, an RRC connection setup message 212, and an RRC connection setup complete message 214 to and from an RNC 204 via a Node B 202. Next, the UE 200 sends a message of a Non Access Stratum (NAS) to the RNC 204 using an initial direct transfer message 216, and selects a radio access bearer and a radio bearer between a core network and the RNC 204 by setting an authentication and security mode. When the UE 200 determines whether to measure the different RAT based on the message information received from the RNC 204 and sends the measurement result of the different RAT to the RNC 204, the RNC 204 determines based on the measurement result whether to hand over to the different RAT which supports the highspeed data service and sends a cell change order message 222 from the UTRAN to the UE 200. The UE 200 transits to the different RAT determined by the RNC 204 and maintains the call.

[9] As above, when the UE determines whether to reselect the cell of the different RAT using the measurement threshold obtained from the SIB in the idle mode and the high threshold is set, the frequent cell reselection between the RATs may be caused. Since the cell reselection between the RATs requires the network access of the UE, the frequent cell reselections are likely to increase the network load and the power consumption of the UE.

[10] As discussed above, upon receiving the call request for the high-speed data service from the user, the UE performs the call connection in the existing UMTS network, measures the different RAT, and then hands over to the RAT of the high-speed data service. As a result, resources are wasted. The unnecessary RRC connections and the additional procedures such as radio access bearer selection increase the network load. Disclosure of Invention Technical Solution

[11] An aspect of the present invention is to address at least the above mentioned problems and/or disadvantages and to provide at least the advantages described below. Accordingly, an aspect of the present invention is to provide an apparatus and a method for determining a Radio Access Technology (RAT) which supports a highspeed data service in a mobile communication system.

[12] Another aspect of the present invention is to provide an apparatus and a method for determining an RAT to support a high-speed data service using a threshold for a network access when a User Equipment (UE) requests a call connection for the highspeed data service in a mobile communication system.

[13] Yet another aspect of the present invention is to provide an apparatus and a method for determining to access a different RAT without accessing a Universal Mobile Telecommunication Service (UMTS) system using a network access threshold when a UE requests a call connection for a high-speed data service in the UMTS system.

[14] The above aspects are achieved by providing a method for determining an RAT which supports a high-speed data service in a mobile communication system. The method includes periodically broadcasting, at a Radio Network Controller (RNC), system information which comprises an RAT list and an RAT access threshold; examining, at a UE, neighbor RATs supporting the high-speed data service using the RAT list; and determining an RAT to connect a Mobile Origination (MO) call by comparing an energy to noise ratio (EJNo) of the examined RAT signal with the RAT access threshold.

[15] According to one aspect of the present invention, a method of a UE for determining an RAT which supports a high-speed data service in a mobile communication system includes periodically receiving system information which comprises an RAT list and an RAT access threshold from a Radio Network Controller (RNC); examining neighbor RATs supporting the high-speed data service using the RAT list; measuring an energy to noise ratio (EJN ₀) of the examined RAT signal; and determining an RAT to connect a Mobile Origination (MO) call by comparing the RAT access threshold with the measured energy to noise ratio.

[16] According to another aspect of the present invention, an apparatus for a UE for determining an RAT which supports a high-speed data service in a mobile communication system includes a communicator for periodically receiving system information which comprises an RAT list and an RAT access threshold from an RNC; a measurer for measuring an energy to noise ratio (E_c/N₀) of neighbor RAT signals supporting the high-speed data service; and an RAT controller for examining neighbor RATs supporting the high-speed data service using the RAT list and determining an RAT to connect an MO call by comparing the energy to noise ratio (EJNo) of the measured RAT signals with the RAT access threshold.

[17] According to yet another aspect of the present invention, a method of am RNC for determining an RAT which supports a high-speed data service in a mobile communication system includes generating a system information message comprising an RAT list and an RAT access threshold; and broadcasting the system information message.

[18] According to still another aspect of the present invention, an apparatus for an RNC for determining an RAT which supports a high-speed data service in a mobile communication system includes a system information message generator for generating a system information message comprising an RAT list and an RAT access threshold; and a communicator for broadcasting the system information message.

[19] Other aspects, advantages, and salient features of the invention will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses exemplary embodiments of the invention. Brief Description of the Drawings

[20] The above and other aspects, features and advantages of certain exemplary embodiments the present invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which:

[21] FIG. 1 illustrates a conventional Inter-RAT measurement threshold;

[22] FIG. 2 illustrates signal flows for Inter-RAT handover of a UE in a conventional

UMTS system;

[23] FIG. 3 illustrates system information periodically broadcast in a mobile communication system according to an exemplary embodiment of the present invention;

[24] FIG. 4 illustrates correlation between the conventional Inter-RAT measurement threshold and an RAT access threshold in the mobile communication system according to an exemplary embodiment of the present invention;

[25] FIG. 5 illustrates structures of an RNC and a UE in the mobile communication system according to an exemplary embodiment of the present invention;

[26] FIG. 6 and FIG. 7 illustrates a call connection method for the high-speed data service at the UE in the mobile communication system according to an exemplary embodiment of the present invention; and

[27] FIG. 8 illustrates operations of the RNC for the high-speed data service in the mobile communication system according to an exemplary embodiment of the present invention.

[28] Throughout the drawings, like reference numerals will be understood to refer to like parts, components and structures. Best Mode for Carrying Out the Invention

[29] The following description with reference to the accompanying drawings is provided to assist in a comprehensive understanding of exemplary embodiments of the present invention as defined by the claims and their equivalents. It includes various specific details to assist in that understanding but these are to be regarded as merely exemplary. Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the embodiments described herein can be made without departing from the scope and spirit of the invention. Also, descriptions of well-known functions and constructions are omitted for clarity and conciseness.

[30] Exemplary embodiments of the present invention provide an apparatus and a method for determining a Radio Access Technology (RAT) to support a high-speed data service using a threshold for network access when a Mobile Origination (MO) call connection for the high-speed data service is requested in a mobile communication system. Hereinafter, signals transmitted and received between a User Equipment (UE) and a Radio Network Controller (RNC) pass through a base station (Node B).

[31] FIG. 3 illustrates system information periodically broadcast in a mobile communication system according to an exemplary embodiment of the present invention.

[32] In FIG. 3, the RNC 304 transmits system information including an RAT information list and an RAT access threshold to each UE 300 via the Node B 302, or transmits only the RAT access threshold to each UE 300.

[33] When a user requests an MO call for the high-speed data service, the UE 300 determines an RAT to support the high-speed data service using the RAT information list and the RAT access threshold of the system information and connects the call using the determined RAT. In more detail, the UE 300 examines neighbor RATs supporting the high-speed data service using the RAT information list, measures an energy to noise ratio (E_c/N₀) of the examined RATs, and compares the E_c/N₀ with the RAT access threshold, and then connects the call through the RAT having the greatest energy to noise ratio amongst the RATs having the energy to noise ratio greater than the RAT access threshold.

[34] Herein, the conventional Inter-RAT measurement threshold and the RAT access threshold of the present invention have the correlation as shown in FIG. 4.

[35] For instance, to move to the RAT supporting the higher-speed data service than the current service, the UE can be serviced by the corresponding RAT by making the inter- RAT measurement threshold higher. By making the RAT access threshold of the present invention higher than the conventional Inter-RAT measurement threshold, the UE can determine to move to the RAT supporting the better data service than the current RAT in the call connection attempt for the high-speed data service. Also, by setting the conventional Inter-RAT measurement threshold lower than the RAT access threshold of the present invention, the frequent cell reselections between the RATs can be reduced.

[36] FIG. 5 is a block diagram of an RNC and a UE in the mobile communication system according to an exemplary embodiment of the present invention.

[37] As shown in FIG. 5, the UE includes a communicator 500, a message processor 502, an SIB processor 504, a call controller 506, an RAT controller 508, and a measurer 510. The RNC includes a communicator 520, a message processor 522, a call controller 524, and an SIB generator 526.

[38] First, the structure of the UE is described below.

[39] The communicator 500 of the UE processes signals transmitted and received over an antenna. Particularly, the communicator 500 periodically receives system information including the RAT list and the RAT access threshold from the RNC and provides the received system information to the message processor 502.

[40] The message processor 502 processes the message output from the communicator

500, provides the call related message to the call controller 506, provides the system information message to the SIB processor 504, processes the call related message output from the call controller 506, and provides the processed message to the communicator 500.

[41] The SIB processor 504 receives the system information message from the message processor 502, acquires the RAT list and the RAT access threshold by analyzing the received system information message, and provides the acquired data to the RAT controller 508.

[42] The call controller 506 controls and processes the MO call requested from the user and the MT call requested from another UE. Particularly, when the user requests the MO call for the high-speed data service, the call controller 506 requests the RAT controller 508 to determine the RAT for the call connection. Upon receiving the determined RAT, the call controller 506 controls and processes the MO call connection through the determined RAT.

[43] When the call controller 506 requests to determine the RAT for the call connection, the RAT controller 508 determines the RAT which supports the high-speed data rate using the RAT list and the RAT access threshold provided from the SIB processor 504. More specifically, the RAT controller 508 examines neighbor RATs supporting the high-speed data service in the RAT list, measures the energy to noise ratio (E_c/N₀) of the examined RATs at the measurer 510, compares the measured energy to noise ratio with the RAT access threshold, selects the RAT having the greatest energy to noise ratio amongst the RATs having the greater energy to noise ratio than the RAT access threshold, and determines the selected RAT as the RAT for the call connection.

[44] The measurer 510 measures the signal energy to noise ratio of a particular RAT under the control of the RAT controller 508 and provides the measured ratio to the RAT controller 508.

[45] Next, the structure of the RNC is explained. [46] The communicator 520 of the RNC processes signals transmitted and received via an antenna. Particularly, the communicator 520 broadcasts the system information message provided from the message processor 522. The message processor 522 processes the message fed from the communicator 520 and provides the processed message to the call controller 524, processes the system information message fed from the SIB generator 526 and provides the processed message to the communicator 500.

[47] The call controller 524 controls and processes the function for the call connection of the corresponding UE by analyzing the message output from the message processor 522.

[48] The SIB generator 526 periodically generates the system information message to be broadcast to the UEs and provides the generated system information message to the message processor 522. Particularly, according to the present invention, the SIB generator 526 generates the system information message including the RAT list and the RAT access threshold.

[49] FIG. 6 and FIG. 7 illustrates a call connection method for the high-speed data service at the UE in the mobile communication system according to an exemplary embodiment of the present invention.

[50] Referring to FIG. 6 and FIG. 7, when the user requests the MO call connection for the high-speed data service in step 601, the UE confirms the RAT list and the RAT access threshold in the system information broadcast from the RNC in step 603.

[51] In step 605, the UE checks whether there are neighbor RATs supporting the highspeed data service in the confirmed RAT list. When there are no RATs supporting the high-speed data service, the UE proceeds to step 623. When there are RATs supporting the high-speed data service, the UE checks whether it is moving fast in step 607.

[52] When the UE is moving fast according to the result of the check, the UE proceeds to step 623. Not moving fast, the UE measures the energy to noise ratio of the signal received from the RAT supporting the high-speed data service in step 609. In step 611, the UE checks whether there are RATs having the energy to noise ratio greater than the RAT access threshold by comparing the measured energy to noise ratio of the RATs with the RAT access threshold.

[53] When there are no RATs having the energy to noise ratio greater than the RAT access threshold, the UE goes to step 623. When there are RATs having the energy to noise ratio greater than the RAT access threshold, the UE selects an RAT having the greatest energy to noise ratio amongst the RATs having the greater energy to noise ratio in step 613 and attempts to acquire the system after moving to the selected RAT in step 615.

[54] In step 617, the UE checks whether the system acquisition is successful or not. When the system acquisition fails, the UE proceeds to step 623. When the system acquisition succeeds, the UE checks whether the cell corresponding to the RAT is available or not in step 619. When the cell is available, the UE connects the call in the cell using the selected RAT in step 621 and then finishes this algorithm. When the cell is not available, the UE connects the call through the available RAT in the region of the UE in step 623 and then finishes this algorithm.

[55] FIG. 8 illustrates operations of the RNC for the high-speed data service in the mobile communication system according to an exemplary embodiment of the present invention.

[56] Referring to FIG. 8, the RNC periodically generates the system information message to be broadcast to the UEs in step 701. According to the present invention, the system information message includes the RAT list and the RAT access threshold. Next, the RNC periodically broadcasts the system information message including the RAT list and the RAT access threshold in step 703 and finishes this algorithm.

[57] When the user of the UE requests the call connection for the high-speed data service in the mobile communication system, the access to the RAT supporting the high-speed data service is determined using the RAT access threshold received over the network and the corresponding call is connected. Therefore, the load to the current network of the UE can be reduced and the high-speed data service can be provided to the user within an even shorter time.

[58] While the invention has been shown and described with reference to certain exemplary embodiments 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 as defined by the appended claims and their equivalents.

Claims

[1] A method for determining a Radio Access Technology (RAT) which supports a high-speed data service in a mobile communication system, the method comprising: periodically broadcasting, at a Radio Network Controller (RNC), system information which comprises an RAT list and an RAT access threshold; examining, at a User Equipment (UE), neighbor RATs supporting the high-speed data service using the RAT list; and determining an RAT to connect a Mobile Origination (MO) call by comparing an energy to noise ratio (E_c/N₀) of the examined RAT signal with the RAT access threshold.

[2] The method of claim 1, wherein the determining of the RAT comprises: measuring an energy to noise ratio of the examined RAT signal; confirming RATs having an energy to noise ratio greater than the RAT access threshold amongst the examined RATs by comparing the measured energy to noise ratio with the RAT access threshold; and determining an RAT having the greatest energy to noise ratio amongst the confirmed RATs as an RAT to perform the MO call connection for the highspeed data service.

[3] The method of claim 2, further comprising: when there are no RATs having the energy to noise ratio greater than the RAT access threshold amongst the examined RATs, connecting the MO call using an existing RAT.

[4] The method of claim 1, further comprising: acquiring a system of the determined RAT; checking whether a corresponding cell of the RAT is available; and connecting an MO call for the high-speed data service using the RAT in the corresponding cell.

[5] A method of a User Equipment (UE) for determining a Radio Access

Technology (RAT) which supports a high-speed data service in a mobile communication system, the method comprising: periodically receiving system information which comprises an RAT list and an RAT access threshold from a Radio Network Controller (RNC); examining neighbor RATs supporting the high-speed data service using the RAT list; measuring an energy to noise ratio (E_c/N₀) of the examined RAT signal; and determining an RAT to connect a Mobile Origination (MO) call by comparing the RAT access threshold with the measured energy to noise ratio.

[6] The method of claim 5, wherein the determining of the RAT comprises: confirming RATs having an energy to noise ratio greater than the RAT access threshold amongst the examined RATs by comparing the RAT access threshold with the measured energy to noise ratio; and determining an RAT having the greatest energy to noise ratio amongst the confirmed RATs as an RAT to perform the MO call connection for the highspeed data service.

[7] The method of claim 6, further comprising: when there are no RATs having the energy to noise ratio greater than the RAT access threshold amongst the examined RATs, connecting the MO call using an existing RAT.

[8] The method of claim 5, further comprising: acquiring a system of the determined RAT; checking whether a corresponding cell of the RAT is available; and connecting an MO call for the high-speed data service using the RAT in the corresponding cell.

[9] An apparatus for a User Equipment (UE) for determining a Radio Access

Technology (RAT) which supports a high-speed data service in a mobile communication system, comprising: a communicator for periodically receiving system information which comprises an RAT list and an RAT access threshold from a Radio Network Controller (RNC); a measurer for measuring an energy to noise ratio (E_c/N₀) of neighbor RAT signals supporting the high-speed data service; and an RAT controller for examining neighbor RATs supporting the high-speed data service using the RAT list and determining an RAT to connect a Mobile Origination (MO) call by comparing the energy to noise ratio (E₀ZNo) of the measured RAT signals with the RAT access threshold.

[10] The apparatus of claim 9, wherein the RAT controller confirms RATs having an energy to noise ratio greater than the RAT access threshold amongst the examined RATs by comparing the RAT access threshold with the measured energy to noise ratio, and determines an RAT having the greatest energy to noise ratio amongst the confirmed RATs as an RAT to perform the MO call connection.

[11] The apparatus of claim 9, wherein, when there are no RATs having the energy to noise ratio greater than the RAT access threshold amongst the examined RATs, the RAT controller connects the MO call using an existing RAT.

[12] A method of a Radio Network Controller (RNC) for determining a Radio Access

Technology (RAT) which supports a high-speed data service in a mobile communication system, the method comprising: generating a system information message comprising an RAT list and an RAT access threshold; and broadcasting the system information message.

[13] An apparatus for a Radio Network Controller (RNC) for determining a Radio

Access Technology (RAT) which supports a high-speed data service in a mobile communication system, comprising: a system information message generator for generating a system information message comprising an RAT list and an RAT access threshold; and a communicator for broadcasting the system information message.