Abstract:
A method and apparatus for performing inter-radio access technology (RAT) measurements includes receiving a long term evolution (LTE) measurement quantity. A measurement gap is received. Measurements for available global system for mobile communication (GSM) cells are performed, and the measurement results are reported.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application No. 60/945,962, filed Jun. 25, 2007, 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 recently initiated a long term evolution (LTE) program to bring new technology, new network architecture, new configuration and new applications and services to the wireless cellular network in order to provide improved spectral efficiency and faster user experiences. In LTE, the reliance on the network-provided neighboring cell information is reduced in order to offload the network burdens and user equipments (UEs) may need to find neighboring cells in other RAT by itself or may be commanded by an eNodeB to locate neighboring base stations and cells or to collect their radio coverage conditions for the purpose of LTE access network self-configuration and self-optimization. Therefore, in an RRC_CONNECTED state, a measurement command and a measurement gap configuration may come for the UE to perform a global system for mobile communication (GSM) band scan/search task to locate or verify available GSM cells. 
         [0004]    However, there is no current measurement quantity or measurement gap purpose allocated to a UE for a GSM Enhanced Data rates for Global Evolution (EDGE) radio access network (GERAN) band scan operation. A complete GERAN band scan or search for identifiable GSM cells may aid an LTE network to reduce broadcast signaling space on the GERAN neighboring cell list and may provide more accurate and timely GSM neighboring cell information. 
         [0005]    In addition, in order to support the LTE self-configuration and self-optimization of an evolved Node B (eNB), individual user equipments may perform neighboring cell scans for the eNB. It would therefore be beneficial to provide a method and apparatus for performing inter-radio access technology (RAT) measurements to support a GERAN band scan. 
       SUMMARY 
       [0006]    A method and apparatus for performing inter-radio access technology (RAT) measurements is disclosed. The method includes receiving a long term evolution (LTE) measurement quantity. A measurement gap is received. Measurements for available global system for mobile communication (GSM/GERAN) cells are performed, and the measurement results are reported. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0007]    A more detailed understanding may be had from the following description, given by way of example in conjunction with the accompanying drawings wherein: 
           [0008]      FIG. 1  shows an example wireless communication system including a plurality of wireless transmit/receive units (WTRUs) and an evolved Node B (eNB); 
           [0009]      FIG. 2  is an example functional block diagram of a WTRU and the eNB of  FIG. 1 ; 
           [0010]      FIG. 3  is a flow diagram of a method for performing inter-RAT measurements; 
           [0011]      FIG. 4  shows an example compressed mode gap pattern parameter; and 
           [0012]      FIG. 5  shows an example diagram depicting gap distances. 
       
    
    
     DETAILED DESCRIPTION  
       [0013]    When referred to hereafter, the terminology “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 terminology “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. 
         [0014]      FIG. 1  shows an example wireless communication system  100  including a plurality of WTRUs  110 , and an evolved Node B (eNB)  120 . As shown in  FIG. 1 , the WTRUs  110  are in communication with the eNB  120 . It should be noted that, although an example configuration of WTRUs  110  and an eNB  120  is depicted in  FIG. 1 , any combination of wireless and wired devices may be included in the wireless communication system  100 . For example, although only one base station (eNB  120 ) is depicted in the wireless communication system  100 , additional base stations may be present, such as in a GERAN system. 
         [0015]      FIG. 2  is an example functional block diagram  200  of a WTRU  110  and the eNB  120  of the wireless communication system  100  of  FIG. 1 . As shown in  FIG. 2 , the WTRU  110  is in communication with the eNB  120 . 
         [0016]    In addition to the components that may be found in a typical WTRU, the WTRU  110  includes a processor  115 , a receiver  116 , a transmitter  117 , and an antenna  118 . The receiver  116  and the transmitter  117  are in communication with the processor  115 . The antenna  118  is in communication with both the receiver  116  and the transmitter  117  to facilitate the transmission and reception of wireless data. The processor  115  of the WTRU  110  is configured to perform inter-RAT measurements to support GERAN band scan, and may be an LTE WTRU. 
         [0017]    In addition to the components that may be found in a typical Node B, the eNB  120  includes a processor  125 , a receiver  126 , a transmitter  127 , and an antenna  128 . The receiver  126  and the transmitter  127  are in communication with the processor  125 . The antenna  128  is in communication with both the receiver  126  and the transmitter  127  to facilitate the transmission and reception of wireless data. 
         [0018]      FIG. 3  is a flow diagram of a method  300  for performing inter-RAT measurements. In step  310 , an LTE measurement quantity is provided to the WTRU  110 . This measurement quantity may aid the WTRU  110  in performing a neighboring cell scan for the eNB  120 . In order to provide this measurement quantity, an E-UTRAN may set a corresponding measurement quantity for inter-RAT measurements. Table 1 below shows an example table format. 
         [0000]    
       
         
               
               
             
               
               
               
               
               
             
           
               
                   
                 TABLE 1 
               
             
             
               
                   
                   
               
               
                   
                 Information Element 
               
             
          
           
               
                 Group name 
                 Need 
                 Multi 
                 Type and reference 
                 Semantics description 
               
               
                   
               
               
                 Measurement quantity for 
                 OP 
                   
                 Intra-frequency measurement 
                   
               
               
                 UTRAN quality estimate 
                   
                   
                 quantity 10.3.7.38 
               
               
                 CHOICE system 
                 MP 
               
               
                 &gt;GSM 
               
               
                 &gt;&gt;Measurement quantity 
                 MP 
                   
                 Enumerated(GSM Carrier 
                 When the measurement quantity 
               
               
                   
                   
                   
                 RSSI, GSM Band Scan/Search) 
                 is GSM Band Scan/Search, the UE 
               
               
                   
                   
                   
                   
                 at provided measurement gaps 
               
               
                   
                   
                   
                   
                 searches the GSM band(s) that it 
               
               
                   
                   
                   
                   
                 supports (see Classmark-II or 
               
               
                   
                   
                   
                   
                 Classmark-III that the UE has 
               
               
                   
                   
                   
                   
                 indicated to the network) for 
               
               
                   
                   
                   
                   
                 available GSM cells 
               
               
                 &gt;&gt;Filter coefficient 
                 MP 
                   
                 Filter coefficient 10.3.7.9 
               
               
                 &gt;&gt;BSIC verification required 
                 MP 
                   
                 Enumerated(required, 
               
               
                   
                   
                   
                 not required) 
               
               
                 &gt;IS2000 
               
               
                 &gt;&gt;TADD E c /I 0   
                 MP 
                   
                 Integer(0 . . . 63) 
                 Admission criteria for neighbours, 
               
               
                   
                   
                   
                   
                 see subclause 2.6.6.2.6 of 
               
               
                   
                   
                   
                   
                 TIA/EIA/IS-2000.5 
               
               
                 &gt;&gt;TCOMP E c /I 0   
                 MP 
                   
                 Integer(0 . . . 15) 
                 Admission criteria for neighbours, 
               
               
                   
                   
                   
                   
                 see subclause 2.6.6.2.5.2 of 
               
               
                   
                   
                   
                   
                 TIA/EIA/IS-2000.5 
               
               
                 &gt;&gt;SOFT SLOPE 
                 OP 
                   
                 Integer(0 . . . 63) 
                 Admission criteria for neighbours, 
               
               
                   
                   
                   
                   
                 see subclause 2.6.6.2.3 and 
               
               
                   
                   
                   
                   
                 2.6.6.2.5.2 of TIA/EIA/IS-2000.5 
               
               
                 &gt;&gt;ADD_INTERCEPT 
                 OP 
                   
                 Integer(0 . . . 63) 
                 Admission criteria for neighbours, 
               
               
                   
                   
                   
                   
                 see subclause 2.6.6.2.5.2 of 
               
               
                   
                   
                   
                   
                 TIA/EIA/IS-2000.5 
               
               
                   
               
             
          
         
       
     
         [0019]    It should be noted that Table 1 is an example format using a UMTS table as an example. 
         [0020]    A measurement gap is then assigned to the WTRU  110  (step  320 ). In order to achieve this, a purpose entry may be set for the GERAN band scan or search. Table 2 below shows an example purpose entry setting for GSM Band Scan/Search. 
         [0000]    
       
         
               
               
               
               
             
           
               
                 TABLE 2 
               
               
                   
               
             
             
               
                 &gt;Transmission 
                 OP 
                   
                   
               
               
                 gap pattern 
               
               
                 sequence 
               
               
                 configuration 
               
               
                 parameters 
               
               
                 &gt;&gt;TGMP 
                 MP 
                 Enumerated(TDD measurement, 
                 Transmission 
               
               
                   
                   
                 FDD measurement, GSM carrier 
                 Gap pattern 
               
               
                   
                   
                 RSSI measurement, GSM Initial 
                 sequence 
               
               
                   
                   
                 BSIC identification, GSM BSIC 
                 Measurement 
               
               
                   
                   
                 re-confirmation, Multi-carrier 
                 Purpose. 
               
               
                   
                   
                 measurement, GSM Band 
               
               
                   
                   
                 Scan/Search) 
               
               
                   
               
             
          
         
       
     
         [0021]    The E-UTRAN may assign to the WTRU  110  measurement gaps with longer gap lengths for the purpose of GSM Band Scan, (e.g., TGL 1  and TGL 2  could be different) with a patterned varying transmit gap distance (TGD) in order for the WTRU  110  to adjust its alignment to different frame timings of the frequency correction channel (FCCH) and synchronization channel (SCH) from different GSM cells. 
         [0022]    Patterned varying TGDs may indicate the time between measurement gaps, (e.g., gap- 1  and gap- 2 ), and vary in distance lengths in a fixed way within the pattern repetition length (TGPL 1 ). For example, a pattern may be ABCABC, where A is equal to ten subframes, B is equal to 6 subframes and C is equal to 15 subframes. The values of A, B and C can be specified in the TGD sub-fields of a TGD-pattern to depict the repeating varying gap distances between gap- 1  and gap- 2  until TGPRC is done. This pattern can be predefined, such as in Standards or it could be determined by the network and signaled to the WTRU  110 . Table 3 below shows a predefined gap pattern. 
         [0000]    
       
         
               
               
               
               
               
             
           
               
                 TABLE 3 
               
               
                   
               
             
             
               
                 &gt;Transmission gap 
                 OP 
                   
                   
                   
               
               
                 pattern sequence 
               
               
                 configuration parameters 
               
               
                 &gt;&gt;TGMP 
                 MP 
                   
                 Enumerated(TDD measurement, FDD 
                 Transmission Gap pattern 
               
               
                   
                   
                   
                 measurement, GSM carrier RSSI 
                 sequence Measurement Purpose. 
               
               
                   
                   
                   
                 measurement, GSM Initial BSIC 
               
               
                   
                   
                   
                 identification, GSM BSIC re-confirmation, 
               
               
                   
                   
                   
                 Multi-carrier measurement, GSM Band 
               
               
                   
                   
                   
                 Scan/Search) 
               
               
                 &gt;&gt;TGPRC 
                 MP 
                   
                 Integer 
                 The number of transmission 
               
               
                   
                   
                   
                   
                 gap patterns within the 
               
               
                   
                   
                   
                   
                 Transmission Gap Pattern 
               
               
                   
                   
                   
                   
                 Sequence. 
               
               
                 &gt;&gt;TGSN 
                 MP 
                   
                 Integer 
                 Transmission Gap Starting 
               
               
                   
                   
                   
                   
                 Slot Number 
               
               
                   
                   
                   
                   
                 The slot number 
               
               
                   
                   
                   
                   
                 of the first transmission 
               
               
                   
                   
                   
                   
                 gap slot within the TGCFN. 
               
               
                 &gt;&gt;TGL1 
                 MP 
                   
                 Integer 
                 The length of the first 
               
               
                   
                   
                   
                   
                 Transmission Gap within the 
               
               
                   
                   
                   
                   
                 transmission gap pattern 
               
               
                   
                   
                   
                   
                 expressed in number of slots 
               
               
                 &gt;&gt;TGL2 
                 MD 
                   
                 Integer 
                 The length of the second 
               
               
                   
                   
                   
                   
                 Transmission Gap within the 
               
               
                   
                   
                   
                   
                 transmission gap pattern. If 
               
               
                   
                   
                   
                   
                 omitted, then TGL2 = TGL1. 
               
               
                   
                   
                   
                   
                 The value of TGL2 shall be 
               
               
                   
                   
                   
                   
                 ignored if TGD is set to “undefined” 
               
               
                 &gt;&gt; TGD-pattern 
                   
                 Integer 
                   
                 One or more Transmission gap 
               
               
                   
                   
                 (1, . . . maxTGDs, 
                   
                 distances as a repeating 
               
               
                   
                   
                 undefined) 
                   
                 pattern in the transmitted order 
               
               
                   
                   
                   
                   
                 of the following TGDs indicating 
               
               
                   
                   
                   
                   
                 the number of LTE sub-frames 
               
               
                   
                   
                   
                   
                 between starting slots of two 
               
               
                   
                   
                   
                   
                 consecutive transmission gaps 
               
               
                   
                   
                   
                   
                 within a transmission gap pattern. 
               
               
                   
                   
                   
                   
                 If there is only one transmission 
               
               
                   
                   
                   
                   
                 gap in the transmission gap pattern, 
               
               
                   
                   
                   
                   
                 this parameter shall be set to 
               
               
                   
                   
                   
                   
                 “undefined”. 
               
               
                 &gt;&gt;&gt;TGD 
                 MP 
                   
                 Integer 
               
               
                   
                   
                   
                 (10, . . . maxTGD) 
               
               
                 &gt;&gt;TGPL1 
                 MP 
                   
                 Integer 
                 The duration of transmission gap 
               
               
                   
                   
                   
                 (1 . . . maxPatternDuration) 
                 pattern 1 in number of frames. 
               
               
                   
               
             
          
         
       
     
         [0023]      FIG. 4  shows an example compressed mode gap pattern parameter  400 .  FIG. 5  shows an example diagram depicting gap distances  500 . As shown in  FIGS. 4 and 5 , gap- 1  and gap- 2  are of different gap lengths. There are 3 TGDs in the TGD-pattern, A, B and C. As shown in the Figures, the distance between the beginning of gap- 1  and the beginning of gap- 2  varies from A to B to C and back to A and such within the TGPL 1 . 
         [0024]    In step  330 , the WTRU  110  searches for an available GSM cell, for example, when the inter-RAT (GERAN) measurement commands the WTRU  110  for “GERAN band scan/search”. The WTRU  110  schedules the GSM band search, (e.g., on the supported GSM frequencies indicated in its Classmark-II/Classmark-III or their LTE equivalent to the network), during the measurement gap allocated in step  320  by the LTE network for the specific “GERAN band scan/search” purpose. 
         [0025]    In one example, the scan/search includes the WTRU  110  tuning to each relevant specific absolute radio frequency channel number (ARFCN) within the band, measuring the waveform to determine whether or not it is above a predefined threshold, synchronizing with the FCCH and SCH of the GSM cell, acquiring the base station identity code (BSIC), and the carrier GSM received signal strength indicator (RSSI). In addition, the WTRU  110  may acquire the public land mobile network identity (PLMN-ID). 
         [0026]    Once an available cell is identified and measurements are completed with respect to that cell, the WTRU  110  may continue to scan/search for the next available GSM frequency/cell, (e.g., using the ARFCN increment approach), with the remaining time of the same measurement gap pattern in the same band until exhausted. For example, when there are no more GSM frequencies in the supported band(s) or when the allocated total length of the gap pattern is depleted. 
         [0027]    If the WTRU  110  supports more than one GERAN band, the WTRU  110  may also use the remaining time of the same measurement gap pattern to continue searching for GSM cells in a different GERAN band until the assigned time is exhausted. The WTRU  110  may complete measurements at the end of a whole measurement gap pattern or at the end of a period specified by the E-UTRAN. 
         [0028]    Once the GERAN band scan/search is complete, the WTRU  110  reports the measurement results along with an indication of the completion of the measurement to the E-UTRAN, and relinquishes any subsequent remaining gaps (step  340 ). Some of the data that the WTRU  110  may report are the GERAN/GSM band, (e.g., GSM 850, P-GSM900, DCS 1800, PCS 1900, and the like), the ARFCN for available cells found, or the GSM carrier RSSI for the ARFCN. Additionally, the WTRU  110  may report the BSIC for the GSM cell, the PLMN-ID for the GSM cell, or the measured RXLEV and/or RXQUAL for the GSM cell. The WTRU  110  may also indicate that measurements are completed. 
         [0029]    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). 
         [0030]    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. 
         [0031]    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.