Abstract:
A method of handling an attach procedure for a MTC device in a wireless communication system is disclosed. The method comprises performing the attach procedure; and not sending an information element in an attach request message associated with the attach procedure.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application No. 61/390,620 filed on Oct. 7, 2010 and entitled “Method to handle attach procedure for the MTC devices”, the contents of which are incorporated herein. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The application relates to a method and a related communication device used in a wireless communication system and related communication device, and more particularly, to a method of handling an attach procedure and a related communication device in a wireless communication system. 
         [0004]    2. Description of the Prior Art 
         [0005]    Machine-type communication (MTC) is one type of data communication including one or more entities not requiring human interactions. That is, the MTC refers to the concept of communication based on a network such as the existing GERAN, UMTS, long-term evolution (LTE), or the like used by a machine device instead of a mobile station (MS) used by a user. The machine device used in the MTC can be called an MTC device. There are various MTC devices such as a vending machine, a machine of measuring a water level at a dam, etc. That is, the MTC is widely applicable in various fields. The MTC device has features different from that of a typical MS. Therefore, a service optimized to the MTC may differ from a service optimized to human-to-human communication. In comparison with a current mobile network communication service, the MTC can be characterized as a different market scenario, data communication, less costs and efforts, a potentially great number of MSs for communication, wide service areas, low traffic per MS, etc. 
         [0006]    Meanwhile, the number of MTC devices is expected to be much greater than the number of legacy devices, and a probability of performing operations of the plurality of MTC devices simultaneously is high due to a feature of atypical machine-to-machine (M2M) service. M2M communication (also referred to as “machine-type communications” or “MTC”) maybe used in a variety of areas. In the area of security, M2M communication may be used in surveillance systems, in backup of telephone landlines, in the control of physical accesses (e.g. to buildings), and in car/driver security. In the area of tracking and tracing, M2M communication may be used for fleet management, order management, Pay As You Drive (PAYD) applications, asset tracking, navigation, traffic information applications, road tolling, traffic optimization, and steering. In the area of payment systems, M2M communication may be used in point of sales, vending machines, customer loyalty applications, and gaming machines. In healthcare, M2M communication may be used for remotely monitoring vital signs, supporting the elderly or handicapped, in web access telemedicine points, and in remote diagnostics. In the area of remote maintenance/control, M2M communication may be used in programmable logic controllers (PLCs), sensors, lighting, pumps, valves, elevator control, vending machine control, and vehicle diagnostics. In the area of metering, M2M communication may be used in applications related to power, gas, water, heating, grid control, and industrial metering. Additionally, M2M communication based on machine type communication (MTC) technology may be used in areas such as customer service. 
         [0007]    M2M communications may take advantage of deployed wireless networks based on Third Generation Partnership Project (3GPP) technologies such as Global System for Mobile Communications (GSM), Universal Mobile Telecommunications System (UMTS), Long Term Evolution (LTE), Long Term Evolution Advanced (LTE-Advanced), and/or other technologies such as WiMAX (Worldwide Interoperability for Microwave Access) or those developed by the Institute for Institute of Electrical and Electronics Engineers (IEEE) and 3GPP2. M2M communications may use networks based on these technologies to deliver business solutions in a cost-effective manner. In a circumstance involving ubiquitous deployment of wireless networks, the availability of the wireless networks may facilitate and/or encourage the deployment and use of M2M WTRUs. Additionally, further enhancements to these technologies may provide additional opportunities for the deployment of M2M-based solutions. 
         [0008]    To receive services, e.g. evolved packet system (EPS) services, the UE needs to register with the network. During a registration procedure, e.g. attach procedure, the UE may first send an “ATTACH REQUEST” message to a core network (e.g. MME). The “ATTACH REQUEST” message includes an international mobile subscriber identity (IMSI), which is stored in a subscriber identity module (SIM) card inside the mobile device, e.g. UE. Because the IMSI uniquely addresses each subscriber, it is seen as critical information from a security point of view and its transmission clearly has to be avoided as much as possible. By spying on and monitoring the IMSI, eavesdropper may track a subscriber&#39;s location, movement, and activities. So the network allocates a temporary UE identity, for example a system architecture evolution (SAE) temporary mobile subscriber identity (S-TMSI), to the UE and renews it frequently in order to reduce the use of IMSI. 
         [0009]    According to subclause 5.3.2.1 and 5.3.3.0 of section 1 of 3GPP specification, a MTC device will perform an attach procedure when the MTC devices selects a PLMN which is not in the equivalent PLMN list of the registered PLMN. In this attach procedure, the MTC device shall always identifies itself with IMSI i.e. It always sends IMSI in mobile Identity parameter. 
         [0010]    Since a mobile station (MS) is sending IMSI in this case, then Information Elements in ATTACH REQUEST Message related to the MS&#39;s temporary Identifier are not needed as the network will proceed with IMSI and ignore the temporary identifier. These Information Elements are redundant. 
       SUMMARY OF THE INVENTION 
       [0011]    A method of handling an attach procedure for a machine type communication (MTC) device in a wireless communication system is provided. 
         [0012]    A method of handling an attach procedure for a MTC device in a wireless communication system is disclosed. The method comprises performing the attach procedure; and not sending an information element in an attach request message associated with the attach procedure. 
         [0013]    A communication device for handling an attach procedure for a MTC device in a wireless communication system, the communication device comprising means for performing the attach procedure; and means for not sending an information element in an attach request message associated with the attach procedure. 
         [0014]    These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]      FIG. 1  illustrates an exemplary MTC ((Machine Type Communication) architecture. 
           [0016]      FIG. 2  is a schematic diagram of an exemplary communication device. 
           [0017]      FIG. 3  is a flow chart of an exemplary process. 
       
    
    
     DETAILED DESCRIPTION 
       [0018]    Please refer to  FIG. 1 , which illustrates an exemplary MTC ((Machine Type Communication) architecture of a wireless communication system  10 . The wireless communication system  10  includes a plurality of MTC devices  100 , a network  110 , a plurality of mobile stations (MSs)  120 , a MTC server  130  and a MTC user  140 . The plurality MTC devices  100  and the plurality of MSs  120  are connected to the network  110 . The MTC server  130  receives information of the MTC devices  100  through the network  110 , and provides the information to the MTC user  140 . The MTC server  130  is located outside of the network  110  or inside of the network  110  and managed by the network operator. 
         [0019]    The network  110  may be referred as to Global System for Mobile Communications (GSM), Universal Mobile Telecommunications System (UMTS), GSM EDGE Radio Access Network (GERAN), Long Term Evolution (LTE), Long Term Evolution Advanced (LTE-Advanced), and/or other technologies such as WiMAX (Worldwide Interoperability for Microwave Access) or those developed by the Institute for Institute of Electrical and Electronics Engineers (IEEE). Please note that MTC devices  320  also can be referred as to user equipments (UEs) in a wireless communication system, which includes mobile phones, computer systems, etc. 
         [0020]    Please refer to  FIG. 2 , which is a schematic diagram of an exemplary communication device  20 . The communication device  20  can be the MTC devices  100 , the network  110 , the MSs  120  or the MTC sever  130  shown in  FIG.1  and may include a processing means  200  such as a microprocessor or ASIC, a memory unit  210 , and a communication interfacing unit  220 . The memory unit  210  may be any data storage device that can store program code  214  for access by the processing means  200 . Examples of the memory unit  410  include but are not limited to a subscriber identity module (SIM), read-only memory (ROM), random-access memory (RAM), CD-ROMs, magnetic tapes, floppy disks, and optical data storage devices. According to processing results of the processing means  200 , the communication interfacing unit  220  can be a radio transceiver or a wire/logical link for communicating with the network  110 . 
         [0021]    Please refer to  FIG. 3 , which is a flow chart of an exemplary process  30 . The process  30  is used for handling an attach procedure for a MTC device. Preferably, the MTC device could be one of the MTC devices  100  in wireless communication system  10 . The process  30  can be compiled into the program code  214  and includes the following steps: 
         [0022]    Step  300 : Start. 
         [0023]    Step  302 : Choose a public land mobile network (PLMN) X, wherein the PLMN X is not in an equivalent PLMN list of registered PLMNs. 
         [0024]    Step  304 : Perform an attach procedure. 
         [0025]    Step  306 : Send an International Mobile Subscriber Identity (IMSI) in an attach request message associated with the attach procedure. 
         [0026]    Step  308 : Do not send an information element in the attach request message. 
         [0027]    Step  310 : End. 
         [0028]    According to the process  30 , the MTC device chooses the PLMN X other than the registered PLMN or the equivalent PLMN of the registered PLMN. The MTC device may support a S1 mode and Iu mode or Gb mode or both. In this situation, the MTC performs the attach procedure instead of RAU/TAU (Routing Area/tracking area) procedure. Then, the MTC device sends the IMSI in the attach request message. Since the MTC device identifies itself with the IMSI, the MTC device does not send the information element in the attach request message. The information element is related to a temporary identifier of a mobile station (MS) and/or information related to last location. Consequently, the MTC device no long send the information element in the attach request message when the MTC device choose the PLMN X other than the registered PLMN or the equivalent PLMN. This reduces redundant additional parameters which are not needed. 
         [0029]    In some examples, the MTC device may camp on the network  110  such as E-UTRAN or UTRAN/GERAN. When the MTC device camps on E-UTRAN, the MTC device is prohibited to send the information element such as at least one of additional TMSI (Temporary Mobile Subscriber Identity) status, old location area identification, additional GUTI (Globally Unique Temporary UE Identity) and last visited registered TAI (Tracking Area Identity). When the MTC device camps on UTRAN/GERAN, the MTC device is prohibited to send the information element such as at least one of at least one of TMSI status, additional mobile identity and additional old routing area identification. 
         [0030]    Please note that the abovementioned steps including suggested steps can be realized by means that could be hardware, firmware known as a combination of a hardware device and computer instructions and data that reside as read-only software on the hardware device, or an electronic system. Examples of hardware can include analog, digital and mixed circuits known as microcircuit, microchip, or silicon chip. Examples of the electronic system can include system on chip (SOC), system in package (Sip), computer on module (COM), and the communication device  20  in which the processing means  200  processes the program code  214  related to the abovementioned processes and the processed results can handle an attach procedure for a MTC device in the wireless communication system  10 . 
         [0031]    To sum up, when a MTC device chooses a PLMN other than the registered PLMN or an equivalent PLMN of the registered PLMN, the MTC device will perform an attach procedure. The MTC device identifies itself with IMSI in an attach request message associated with the attach procedure. So in the attach request message message, the MTC device is prohibited to send an information element related to temporary identifiers of the MS and/or information related to last location. Consequently, the redundant additional parameters can be reduced. 
         [0032]    Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.