Abstract:
A method and apparatus for providing an ETWS message to a wireless transmit receive unit (WTRU). The WTRU is configured to receive a paging message indicating a change in system information, wherein in response to the paging message to receive a system information block (SIB) 1 to determine a schedule for reception of earthquake and tsunami warning system (ETWS) information in system information blocks (SIBs). The WTRU is further configured to receive the SIBs with the ETWS information and to separately receive segments of an ETWS message and to combine the segments to reproduce the ETWS message.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Non-Provisional application Ser. No. 12/486,029 filed Jun. 17, 2009 and Provisional Application No. 61/074,229 filed Jun. 20, 2008, which is incorporated by reference as if fully set forth. 
     
    
     FIELD OF INVENTION 
       [0002]    This application is related to wireless communications. 
       BACKGROUND 
       [0003]    The Third Generation Partnership Project (3GPP) has initiated the Long Term Evolution (LTE) program to bring new technology, new network architecture, new configurations and new applications and services to wireless networks in order to provide improved spectral efficiency and faster user experiences. 
         [0004]      FIG. 1  shows an overview of an Evolved Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access Network (E-UTRAN)  100  in accordance with the prior art. As shown in  FIG. 1 , E-UTRAN  100  includes three eNodeBs (eNBs)  102 , however, any number of eNBs may be included in E-UTRAN  100 . The eNBs  102  are interconnected by an X2 interface  108 . The eNBs  102  are also connected by an S1 interface  106  to the Evolved Packet Core (EPC)  104  that includes a Mobility Management Entity (MME)  112  and a Serving Gateway (S-GW)  110 . 
         [0005]    System information (SI) is information that is broadcast within a cell and provides information about configurations and parameters that are common to at least some of the wireless transmit receive units (WTRUs) in the cell. 
         [0006]    System information messages may include parameters such as network identification, neighbouring cells, channel availability and power control requirements, for example. 
         [0007]    An LTE network may include a severe earthquake and tsunami warning service (ETWS). The ETWS may warn wireless telephone users of an imminent or nearby man-made or natural disaster. In the LTE radio access network, ETWS information is distributed via system information broadcast. 
       SUMMARY 
       [0008]    Disclosed is a method and apparatus for providing an ETWS message to a wireless transmit receive unit (WTRU). The WTRU is configured to receive a paging message indicating a change in system information, wherein in response to the paging message to receive a system information block (SIB) 1 to determine a schedule for reception of earthquake and tsunami warning system (ETWS) information in system information blocks (SIBs). The WTRU is further configured to receive the SIBs with the ETWS information and to separately receive segments of an ETWS message and to combine the segments to reproduce the ETWS message. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    A more detailed understanding may be had from the following description, given by way of example in conjunction with the accompanying drawings wherein: 
           [0010]      FIG. 1  shows an overview of an E-UTRAN in accordance with the prior art; 
           [0011]      FIG. 2  shows an example wireless communication system including a plurality of WTRUs and an eNB in accordance with one embodiment; 
           [0012]      FIG. 3  is a block diagram of a WTRU and the eNB of  FIG. 2 ; 
           [0013]      FIG. 4  shows a method of non-overlapping emergency SI message transmission in accordance with one embodiment; and 
           [0014]      FIG. 5  shows a method of overlapping transmission of emergency SI messages in accordance with another embodiment. 
       
    
    
     DETAILED DESCRIPTION 
       [0015]    When referred to hereafter, the term “wireless transmit/receive unit (WTRU)” includes, but is not limited to, a user equipment (UE), a mobile station, a fixed or mobile subscriber unit, a pager, a cellular telephone, a personal digital assistant (PDA), a computer, or any other type of user device capable of operating in a wireless environment. When referred to hereafter, the term “base station” includes, but is not limited to, a Node B, a site controller, an access point (AP), or any other type of interfacing device capable of operating in a wireless environment. 
         [0016]      FIG. 2  shows a wireless communication system  200  including a plurality of WTRUs  210  and an e Node B (eNB)  220 . As shown in  FIG. 2 , the WTRUs  210  are in communication with the eNB  220 . Although three WTRUs  210  and one eNB  220  are shown in  FIG. 2 , it should be noted that any combination of wireless and wired devices may be included in the wireless communication system  200 . 
         [0017]      FIG. 3  is a functional block diagram  300  of a WTRU  210  and the eNB  220  of the wireless communication system  200  of  FIG. 2 . As shown in  FIG. 2 , the WTRU  210  is in communication with the eNB  220 . The WTRU  210  is configured to receive and process emergency and non-emergency SI messages. 
         [0018]    In addition to the components that may be found in a typical WTRU, the WTRU  210  includes a processor  315 , a receiver  316 , a transmitter  317 , and an antenna  318 . The WTRU  210  may also include a user interface  321 , which may include, but is not limited to, an LCD or LED screen, a touch screen, a keyboard, a stylus, or any other typical input/output device. The WTRU  210  may also include memory  319 , both volatile and non-volatile as well as interfaces  320  to other WTRU&#39;s, such as USB ports, serial ports and the like. The receiver  316  and the transmitter  317  are in communication with the processor  315 . The antenna  318  is in communication with both the receiver  316  and the transmitter  317  to facilitate the transmission and reception of wireless data. 
         [0019]    In addition to the components that may be found in a typical eNB, the eNB  220  includes a processor  325 , a receiver  326 , a transmitter  327 , and an antenna  328 . The receiver  326  and the transmitter  327  are in communication with the processor  325 . The antenna  328  is in communication with both the receiver  326  and the transmitter  327  to facilitate the transmission and reception of wireless data. The eNB  220  is configured to transmit and process emergency and non-emergency SI messages. 
         [0020]    A natural or man-made disaster may occur within an area that is served by a wireless telephone service. Users located in a particular serving cell area may require immediate information and/or evacuation. If so, emergency system information messages may be used to transmit emergency instructions and information to users in the affected areas, such as evacuation information, for example. The emergency system information messages may also be used to inform users adjacent to the evacuation area that an emergency is occurring, and to inform users who are located in an area not directly affected by the emergency, but who may require information updates regarding the disaster. 
         [0021]    The system information can include an emergency information indicator. The emergency information indicator may be, for example, a flag, a particular bit or string of bits that may indicate the type of emergency information being received by the WTRU. The emergency information indicator may be placed, for example, in the cell entries in the neighboring cell list or a block list. 
         [0022]    Emergency information may require larger data bandwidth for possible disaster handling, that is, more resource blocks, than non-emergency information. Due to the relatively large size of emergency information, a WTRU may require larger resources to receive the necessary emergency information. Emergency information indicators are carried in system information, which is carried on a downlink shared channel, such as the physical downlink shared channel (PDSCH), for example. Resources for the PDSCH are carried on a downlink control channel, such as the physical downlink control channel (PDCCH). The resource scheduling for emergency information may be different than the scheduling required for non-emergency information due to the relatively large size of the emergency information. This may require the use of a number scale representation or format that is different from that used for non-emergency information resource scheduling. 
         [0023]    Therefore a specialized ETWS radio network temporary identifier (ETWS_RNTI) may be used with emergency information notification, and may be used to obtain the PDSCH resources for reading the system information blocks (SIBs) carrying emergency information notification. A radio network temporary identifier (RNTI) may be used to identify a WTRU when a radio resource control (RRC) connection is present, or used to identify special network service information available to all the WTRUs. The ETWS_RNTI may be used to identify to all WTRUs that network or public emergency information is available for retrieval. As emergency information may be broadcast with a primary notification and a secondary notification, the ETWS_RNTI may be used to receive emergency information when the primary ETWS notification is on, and may take higher priority than other RNTI signal processing. 
         [0024]    Non-emergency SIB transmission is periodic. Emergency information SIB transmission may also have a particular period (T ETWS-SI ). The period may be at least, for example, 128 or 256 frames, so that transmission is easier and to accommodate potential retransmission segments. Furthermore, the emergency information SI transmission may employ a voluntary retransmission scheme that automatically sends redundant information without waiting for a negative acknowledgement signal (NACK) so that each WTRU can reliably receive the emergency information SIB(s) in one defined period. 
         [0025]    Non-emergency SI messages are transmitted within periodically occurring time domain windows using dynamic scheduling. Each SI message is associated with a SI-window. SI-windows containing different SI messages do not overlap. That is, within one SI-window only the corresponding SI message is transmitted. The length of the SI-window is common for all SI messages, and is configurable. Within the SI-window, the corresponding SI message can be transmitted a number of times in any subframe. The WTRU may acquire the detailed time and frequency domain scheduling from decoding the SI-RNTI on the PDCCH. 
         [0026]    In one embodiment, emergency SI messages may be scheduled in a non-overlapping manner, which means that emergency SI messages and non-emergency SI messages are not transmitted simultaneously. Non-overlapping emergency SI message transmission may be scheduled at the same time, interleaved as segments, as with non-emergency SI message transmission. The emergency SI messages may be carried in relatively small consecutive sub-frames that are not significantly larger than the non-emergency SI transmission window length. The transmission of emergency SI messages may be scheduled according to the formula: 
         [0000]        SFN T   ETWS-SI =0 and  X= ( n− 1)* Y;   Equation (1)
 
         [0027]    wherein T ETWS-SI  is the emergency SI message periodicity, X is the non-emergency SI message offset, n is the number of non-emergency SI messages and Y is periodicity of the non-emergency SI messages. 
         [0028]    The emergency SI information messages may be placed in at the end of the non-emergency SI messages. Alternatively, the emergency SI messages can be placed in the beginning or in the middle of the non-emergency messages. The location of the emergency SI messages may be signaled to the WTRU in a system information block, such as SIB-1, for example. 
         [0000]    An offset (ETWS_Offset denoted as X ETWS-SI ) can be applied to the emergency SI messages. The ETWS_Offset allows the transmission of the emergency SI messages without overlapping non-emergency SI messages. 
         [0000]        SFN  mod  T   ETWS-SI   =X   ETWS-SI   Equation (2)
 
         [0029]    where the X ETWS-SI  is a frame offset [0, . . . , P] for the emergency SI messages and P is the shortest periodicity among all SIs. The X ETWS-SI  could be signaled from the network. 
         [0030]      FIG. 4  shows a method of non-overlapping emergency SI messages transmission  400  in accordance with one embodiment. The emergency SI messages  402  are transmitted after the non-emergency SI messages  404 . 
         [0031]    Alternatively, emergency SI messages may be transmitted up to a point where the non-emergency SI messages begin. No offset is required. If there are more emergency SI messages to be transmitted after the non-emergency SI message point is reached, the balance of the emergency SI messages may be transmitted as segments between the non-emergency SI messages. The emergency SI message segments may be transmitted in sub-frames in the T ETWS-SI  period that do not contain non-emergency SI messages. The WTRU may receive a signal from a network node, such as an eNodeB, for example, that contains an indication as to which of the sub-frames to use. The indication may be a bitmap, for example. Alternatively, the WTRU may receive the indication in a primary ETWS notification message or an SIB, such as SIB-1 for example. 
         [0032]    The Tx-window-size for emergency SI messages (Y ETWS-SI ) can be made equal to or less than the Tx-window size of non-emergency SI messages (Y) if more frequency spectrum bandwidth, or resource blocks (RBs), can be assigned to transmit the emergency SI messages. Y ETWS-SI  can be signaled and transmitted in an SIB, such as SIB-1, for example. It may be signaled only when the primary ETWS notification is activated or can be always be part of the SIB. Alternatively, Y ETWS-SI  can also be sent in the primary ETWS notification message or in a paging message used to indicate that a change in system information is upcoming. 
         [0033]    If the emergency SI messages are scheduled to be transmitted in the beginning or in the middle of the non-emergency SI messages, and Y ETWS-SI  is not the same as Y, then the offset X=(n−1)*Y can be computed as: 
         [0000]        X =( n− 2)* Y  for  n  before  n ′ of the ETWS SI,
 
         [0000]      or 
         [0000]        X =( n′− 2)* Y+Y   ETWS-SI +( n− 1− n ′)* Y;  for  n  after  n′. 
 
         [0034]    In another embodiment, emergency SI messages may be broadcast overlapped with non-emergency SI messages. This means that an anticipated large volume of emergency data may be handled by WTRUs configured to receive emergency SI messages while the WTRU is also receiving a non-emergency signal. 
         [0035]    Transmission of emergency SI messages may be concentrated or distributed. If the transmission is concentrated, consecutive sub-frames may be equal to or larger than Y, the non-emergency SI Tx-window-size. The scheduling of emergency SI messages may not be restricted by non-emergency SI messages, as defined by the equation: 
         [0000]        SFN  mod  T   ETWS-SI   =X   ETWS-SI , 
         [0036]    where X ETWS-SI  is a frame offset (0, . . . , P). 
         [0037]    If transmission of emergency SI messages is distributed, the emergency SI messages may be segmented into SIBs and/or sub-SIBs based on the content and size of the emergency SI message. The emergency information SI transmission unit may use M consecutive sub-frames with J RBs each, where M and J are integers, such that the amount of data transmitted equals J*M for each emergency information receiving occasion. The total size of the emergency SI message includes the size of any retransmission redundancy, if scheduled. The number of reception occasions (O ETWS-IS ) equals ceiling[total ETWS-SI size div (J*M)]. If J varies, then the number of reception occasions equals ceiling[(T ETWS-SI ×10) div M in subframes]. 
         [0038]      FIG. 5  shows a method of overlapping transmission of emergency SI messages  500  in accordance with another embodiment. The emergency SI messages  502  are segments and are evenly distributed throughout the emergency SI message period T ETWS    506 . The emergency SI messages  502  are overlapped with the non-emergency SI messages  504 . 
         [0039]    The distance between the start of two emergency information Tx-windows between repeat transmission occasions is known as the Occasion frame offset (ETWS-OF). In units of sub-frames, ETWS-OF=(T ETWS-SI *10) div O ETWS-IS . Alternatively, the ETWS-OF may be configured such that ETWS-OF*(O ETWS-SI )&lt;=(T ETWS-SI *10). 
         [0040]    The reception occasions for a WTRU are at frames, starting at SFN mod T ETWS-SI =X ETWS-SI , defined by the equation: 
         [0000]      [ X   ETWS-SI   , X   ETWS-SI +ETWS-OF/10,  X   ETWS-SI +(2*ETWS-OF)/10,  X   ETWS-SI +(3*ETWS-OF)/10, . . . ,  X   ETWS-SI −1)*ETWS-OF/10].
 
         [0000]    The subframe offset in the respective frame is equal to (n*ETWS-OF) mod  10 . 
         [0041]    Emergency SI message segments can be transmitted over non-emergency traffic in a specified pattern. The pattern can be signaled in an SIB, such as SIB-1, for example, starting at a frame defined by: 
         [0000]        SFN  mod  T   ETWS-SI   =X   ETWS-SI . 
         [0042]    The pattern may be Ax+By+Cz+ . . . where A, B and C . . . are the number of repeated occurrences of offset-x, offset-y and offset-z respectively, such that A+B+C&gt;=O ETWS-IS . For example, the signaling may show that A=3, B=1, C=5, x=24, y=40, z=38. This indicates that from the start, there will be three transmission occurrences in occurrence group A. The start of the second occurrence in occurrence group A is 24 sub-frames from the beginning of the first occurrence. There is one occurrence in occurrence group B, which is 40 sub-frames from the beginning of the last occurrence of occurrence group A, and the five occurrences in occurrence group C are each 38 sub-frames from the beginning of the last occurrence. Given the patterned distribution, one ETWS-RNTI may be able to describe all emergency SI message reception occasions and resource block (RB) allocations. It is used only when the primary ETWS notification is ON. 
         [0043]    The PDCCH format to describe the ETWS-SI resources can be in a format similar to PDCCH format 1C, which is currently used to for random access channel (RACH) response, paging, and notification of dedicated broadcast channel (D-BCH). The PDCCH format used for the ETWS-SI will multiply the ETWS-RNTI on the cyclic redundancy check (CRC) of the PDDCH. Hence, when the UE decodes the PDCCH, it can verify whether their PDCCH is addressed to the ETWS-RNTI. 
         [0044]    Although features and elements are described above in particular combinations, each feature or element can be used alone without the other features and elements or in various combinations with or without other features and elements. The methods or flow charts provided herein may be implemented in a computer program, software, or firmware incorporated in a computer-readable storage medium for execution by a general purpose computer or a processor. Examples of computer-readable storage mediums include a read only memory (ROM), a random access memory (RAM), a register, cache memory, semiconductor memory devices, magnetic media such as internal hard disks and removable disks, magneto-optical media, and optical media such as CD-ROM disks, and digital versatile disks (DVDs). 
         [0045]    Suitable processors include, by way of example, a general purpose processor, a special purpose processor, a conventional processor, a digital signal processor (DSP), a plurality of microprocessors, one or more microprocessors in association with a DSP core, a controller, a microcontroller, Application Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs) circuits, any other type of integrated circuit (IC), and/or a state machine. 
         [0046]    A processor in association with software may be used to implement a radio frequency transceiver for use in a wireless transmit receive unit (WTRU), user equipment (UE), terminal, base station, radio network controller (RNC), or any host computer. The WTRU may be used in conjunction with modules, implemented in hardware and/or software, such as a camera, a video camera module, a videophone, a speakerphone, a vibration device, a speaker, a microphone, a television transceiver, a hands free headset, a keyboard, a Bluetooth® module, a frequency modulated (FM) radio unit, a liquid crystal display (LCD) display unit, an organic light-emitting diode (OLED) display unit, a digital music player, a media player, a video game player module, an Internet browser, and/or any wireless local area network (WLAN) or Ultra Wide Band (UWB) module.