Abstract:
This application is related to a method and apparatus for optimizing the transmission of PLMN-IDs in a wireless network. This is accomplished by reducing the amount of bandwidth required to transmit a given set of PLMN-IDs.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application Ser. No. 60/912,068 filed on Apr. 16, 2007, which is incorporated by reference as if fully set forth. 
     
    
     FIELD OF INVENTION 
       [0002]    The present invention is related to wireless communication systems. More particularly, the present invention is related to methods of optimizing the transmission of multiple public land mobile network identifiers (PLMN-ID)s by compressing one or more PLMN-ID components. 
       BACKGROUND 
       [0003]    The third generation partnership project (3GPP) has initiated the 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. As part of that program, LTE system information on the evolved-Universal Mobile Telecommunications Service (UMTS) Terrestrial Radio Access Network (E-UTRAN) should also support the network sharing feature by publishing multiple Public Land Mobile Network-Identifiers (PLMN-IDs) on the broadcast channels (BCH) on each of the LTE cells, and therefore on the primary-BCH (P-BCH) or dynamic-BCH, often enough so that a wireless transmit/receive unit (WTRU) can receive the PLMN-IDs in time to decide which PLMN it should access. 
         [0004]    A PLMN-ID consists of a mobile country code (MCC) component and a mobile network code (MNC) component. A MCC may range numerically from 0 to 999. Therefore, a 10-bit field is required to represent (store) this 3-digit number. A MNC may also range from 0 to 999. It could be a 2 or 3-digit number. To facilitate network sharing in LTE, as well as other types of networks such as UMTS, a list of PLMN-IDs should be broadcasted to all of the wireless WTRUs in a cell. 
         [0005]    UMTS Release-6 and 3GPP Work Group 2 proposals specify that multiple PLMN-IDs should be transmitted in the system information broadcast in the Master Information Block or the Broadcast Channel (BCH). In UMTS the MCC is marked OPTIONAL. If the PLMN-ID&#39;s MCC is the same as a previous PLMN-ID&#39;s MCC, then the MCC is not repeated in the message. Consequently, the present/not-present indicator takes one-bit in the formatted message, as shown in Table 1. 
         [0000]    
       
         
               
             
               
               
               
             
           
               
                 TABLE 1 
               
             
             
               
                   
               
               
                 Prior Art for multiple PLMN-ID List formatting 
               
             
          
           
               
                 MCC field value 
                 MCC field length 
                 Comment 
               
               
                   
               
               
                 MCC1 
                 10-bit 
                   
               
               
                 MCC2 
                   
                 Presence bit (P-bit) exist in 
               
               
                   
                   
                 Abstract Syntax Notation.One 
               
               
                   
                   
                 (ASN.1) form, if 1, 
               
               
                   
                   
                 field length = 10, 
               
               
                   
                   
                 if 0, MCC2 == MCC1, MCC-2 
               
               
                   
                   
                 is not sent, and field length = 0 
               
               
                 MCC3 
                 10-bit 
                 Same as above 
               
               
                 ;;; 
                 10-bit 
                 ;; 
               
               
                 MCCn 
                 10-bit 
                 ;; 
               
               
                   
               
             
          
         
       
     
         [0006]    In LTE, P-BCH bandwidth is very limited. Sending up to a maximum of 6 PLMN-IDs in a system block on the P-BCH is considered very expensive. Therefore, it would be desirable to optimize the use of bandwidth for efficient transmission of multiple PLMN-IDs. 
       SUMMARY 
       [0007]    This application is related to a method and apparatus for optimizing the transmission of PLMN-IDs in a wireless network. This is accomplished by reducing the amount of bandwidth required to transmit a given set of PLMN-IDs. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]    A more detailed understanding may be had from the following description, given by way of example in conjunction with the accompanying drawings wherein: 
           [0009]      FIG. 1  is a flow chart of a method for optimizing PLMN-ID field lengths; and 
           [0010]      FIG. 2A-2B  is a flow chart of an alternative method of optimizing PLMN-ID field lengths using deltas. 
           [0011]      FIG. 3  shows one example of an implementation of an embodiment in a WTRU. 
           [0012]      FIG. 4  illustrates an embodiment in wireless network with different WTRUs (mobile device and an evolved Node B). 
       
    
    
     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, a base station, or any other type of 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, an evolved Node-B, a site controller, an access point (AP), or any other type of interfacing device capable of operating in a wireless environment. When referred to hereafter, the terminology “format” is used interchangeably with the word “store.” When referred to hereafter, the terminology “data” refers to any type of information including but not limited to PLMN-IDs, PLMN-ID components, MNCs, MCCs, numbers, numerical identifiers, numerical values, symbols, symbolic values, etc. Throughout this application, the use of following notation: MCC-n and MCC n , are equivalent and interchangeable. 
         [0014]    A MCC may have a value ranging from 0 to 999. Therefore, the minimum field length required to represent (store) a given MCC is 10-bits. However, not every MCC needs a full 10-bit field to convey its value. For example, a MCC of 111 may be stored in a 7-bit field. By using ┌Log 2  MCC┐ (a ceiling function for rounding up to the next smallest integer, e.g.: 3.23 to 4), the field length required to store a MCC may be reduced to less than 10 bits. Moreover, this technique does not require a field length indicator to be sent to a receiver (WTRU, mobile phone, etc.). A receiver, may predict the actual field length by using the following property: if a≧b≧0 then log 2  a≧log 2  b. 
         [0015]    Since log 2  a≧log 2  b, multiple PLMN-IDs can be sorted into descending order, such that MCC-a is greater than or equal to MCC-b, and so on. When the first PLMN-ID is transmitted, it will contain MCC-a and the MCC-a component of the PLMN-ID will use the largest possible MCC field length (10-bits) and each subsequent PLMN-ID is transmitted containing a different MCC (say MCC-b) using a field length derived from the previous MCC value, ┌Log 2  MCC-a┐-bit field length. Therefore, each of the subsequent MCCs will use a field length derived from the previous MCC that is always less than or equal to the conventional 10-bit fixed field length. As previously noted, this solution also eliminates the need for a separate length indicator when transmitting PLMN-IDs. Thus, the field length of a given PLMN-ID (other than the first PLMN-ID with largest MCC) is reduced, and the aggregate field length and the time required for the transmission of PLMN-IDs is reduced. 
         [0016]      FIG. 1  displays an example of a method in accordance with one embodiment. At step  110 , all PLMN-IDs are sorted based upon their respective MCC into descending numerical order, such that MCC-1&gt;=MCC-2&gt;=. . . &gt;=MCC-n and so on, into a list (e.g.: a table or equivalent structure). This results in a list of PLMN-IDs [MCC-1, . . . MCC-n], where n is less than or equal to six (6) (the value six (6) is based upon existing standards, however, this embodiment works equally well with any value of n), with MCC-1 having the greatest MCC value. At step  120 , the MCC field of the first PLMN-ID (the one containing MCC-1) is formatted (stored) into a 10-bit field. Next, the rest of the PLMN-ID (the MNC) is stored into a corresponding fixed field (since the MNC can be a 2 or 3 digit number, the length of the MNC field will be 7-bits or 10-bits and may also require an additional one or two bit length indicator). At step  130 , the MCC field of the next PLMN-ID (the one containing MCC-2) is stored into a field of length ┌Log 2  MCC-1┐ if Log 2  MCC-1 is not an integer, otherwise the MCC field of the next PLMN-ID (MCC-2) is stored into a field of length ┌Log 2  MCC-1┐+1. Then the corresponding MNC (the rest of the PLMN-ID) is stored into its fixed field. Next, the MCC field of the next PLMN-ID (the one containing MCC-3) is stored into a field of length ┌Log 2  MCC-2┐ if Log 2  MCC-2 is not an integer, otherwise the MCC field of the next PLMN-ID (the one containing MCC-3) is stored into a field of length ┌Log 2  MCC-2┐+1, then the corresponding MNC is stored into its fixed field and so on until the end of the list is reached at step  140 . In general, the MCC field of PLMN-ID-n (the one containing MCC-n) is formatted (stored) into a field of length ┌Log 2  MCC-(n−1)┐ if Log 2  MCC-(n−1) is not an integer, otherwise the MCC field of PLMN-ID-n (the one containing MCC-n) is stored into a field of length ┌Log 2  MCC-(n−1)┐+1. In every case, the full field length of a PLMN-ID will be the sum of the following: 
         [0017]    1 bit (for the p-bit); 
         [0018]    ┌Log 2  MCC-(n−1)┐ bits if Log 2  MCC-(n−1) is not an integer, or otherwise ┌Log 2  MCC-(n−1)┐+1 bits; and 
         [0019]    the field length, in bits, of the MNC field. 
         [0000]                                  TABLE 2                   Implicit MCC Field Length Reduction       illustration (without MNC or p-bit)            MCC field value   MCC field length   Comment               MCC-1   10-bit   Greatest MCC value       MCC-2   ┌Log 2  MCC-1┐ if   Presence bit (P-bit)           Log 2  MCC-1 ≠ integer, else   still exist           ┌Log 2  MCC-1┐+1       MCC-3   ┌Log 2  MCC-2┐ if   Presence bit (P-bit)           Log 2  MCC-2≠ integer, else   still exist           ┌Log 2  MCC-2┐+1       ; ; ;       Presence bit (P-bit)               still exist       MCC-n   ┌Log 2  MCC-(n−1)┐ if   Presence bit (P-bit)           Log 2  MCC-(n−1)≠ integer,   still exist           else           ┌Log 2  MCC-(n−1)┐+1                    
After this processing completes the list is transmitted to one or a plurality of mobile devices (WTRU, mobile phone, etc.). In general, for MCC-2, the field length saving is (10−┌Log 2  MCC-1┐), for MCC-3 the field length saving is (10−┌Log 2  MCC-2┐) and for MCC-n the field length saving is (10−┌Log 2  MCC-(n−1)┐). The combined savings achieved by this optimization method can be expressed as
 
         [0000]    
       
         
           
             
               
                 [ 
                 
                   
                     
                       ( 
                       
                         N 
                         - 
                         1 
                       
                       ) 
                     
                     × 
                     10 
                   
                   - 
                   
                     
                       ∑ 
                       
                         m 
                         = 
                         1 
                       
                       
                         n 
                         - 
                         1 
                       
                     
                      
                     
                       
                         Log 
                         2 
                       
                        
                       
                         MCC 
                         m 
                       
                     
                   
                 
                 ) 
               
               ] 
             
             . 
           
         
       
     
         [0000]    Therefore, if the individual MCC values in the multiple PLMN-ID list are numerically small, that is, less than or equal to 255 (7-bits), then this method is very efficient. 
         [0020]    Referring now to  FIG. 2 , if the individual values of MCCs in the multiple PLMN-ID List are in the high value range, that is, greater than or equal to 256, while the value differences between them are relatively small (less than or equal to 63), another embodiment shown in  FIG. 2  may be used. This embodiment results in a delta/offset field length that will be smaller than the typical field length required to store a MCC value in a PLMN-ID transmission. 
         [0021]    The method  200  begins at step  205  in  FIG. 2A , where given a list of PLMN-IDs, the method sets MCC-1 to the MCC value of the PLMN-ID in the list containing the largest MCC (the one with the greatest numerical value). If more than one greatest MCC exists, the one with the largest MNC is chosen. At step  210 , the rest of the PLMN-IDs are sorted in ascending order based upon their respective MCC value such that MCC-2≦MCC-3≦ . . . ≦MCC-n (if any PLMN-IDs have MCCs that are equal, then they are placed in the list in ascending order based upon their respective MNC value). At step  215 , the value differences or deltas δ MCC-1,m  (m=2, . . . , n) between MCC-1 and each of the other MCCs (e.g.: δ MCC-1,2 =MCC-1−MCC-2) are calculated and at step  220 , each result is stored into a delta-list (e.g.: a table or equivalent structure) in descending order, such that, δ MCC-1,2 &gt;=δ MCC-1,3 &gt;=, . . . , δ MCC-1,n , where n=2, 3, . . . , N (where N≦6 in LTE). In particular if there are deltas (δ MCC-1,m ) equal to 0, which means that some MCCs are equal to MCC-1, then the zero-delta(s) are placed in the front of the delta-list, such that δ MCC-1,2 =0, δ MCC-1,3 &gt;=δ MCC-1,4 &gt;=, . . . , δ MCC-1,n ; this condition only occurs if one or more sequential delta values, beginning with the second delta value, are zero (one or more MCCs are equal to MCC-1). 
         [0022]    At step  225 , the multiple PLMN-IDs are arranged starting with MCC-1 and the rest according to their order in the delta-list, such that [MCC-1, MCC-2 . . . MCC-n], where n is &lt;=6 (typically, n=5 or 6 in LTE or WCDMA respectively, however, this embodiment will work with any value for n) and that MCC-2=MCC-1−δ MCC-1,2 , MCC-3=MCC-1δ MCC-1,3 , and so on. The aranging procedure may use a new list. In general, MCC-n=MCC-1−δ MCC-1,n ; utilizing this relationship, a receiver is able to derive the MCC values from the transmitted MCC-1 and the transmitted deltas. 
         [0023]    At step  230 , the MCC-1 is formatted (stored) into a 10-bit field and the rest of the PLMN-ID (the MNC component) is stored in a corresponding additional field (the total field length will be 10 bits+the length required to store the MNC component). The p-bit is not in the MCC-1 entry. 
         [0024]    At steps  240  and  244 , any zero-delta, for example, δ MCC-1,2 , MCCs are formatted by setting the presence-bit to 0 (no MCC or delta values are stored in the field (i.e.: a field length=0)), if any zero-delta-MCCs exist, the rest of the PLMN-ID (the MNC component) is stored in a corresponding additional field (thus the total field length for a PLMN-ID in this case is the length required to store the MNC component +1 (for the p-bit)); 
         [0025]    At step  242 , the first non-zero delta, say δ MCC-1,3  is formatted into a ┌Log 2  MCC-1┐ length field, if (Log 2  MCC-1) is not an integer, otherwise the first non-zero delta is formatted into a ┌Log 2  MCC-1┐+1 length field, the presence bit (p-bit) is set to 1 and the rest of the PLMN-ID (the MNC component) is stored in a corresponding additional field (the total field length will be ┌Log 2  MCC-1┐ bits if (Log 2  MCC-1) is not an integer, otherwise the total field length will be ΠLog 2  MCC-1┐+1 bits, + the length required to store the MNC component +1 bit (for the p-bit)); 
         [0026]    Continuing in  FIG. 2B  at step  260 , subsequent deltas are formatted (until the end of the list is reached) such that: 
         [0027]    At step  250 , if the δ MCC-1,n  equals the previous delta δ MCC-1,(n−1) , at  252 , the presence bit is set to 0, a delta value is not stored (no bits are used to store the delta value, e.g. a 0-bit field length) and the rest of the PLMN-ID (the MNC component) is stored in a corresponding additional field (the total field length in this case is the length required to store the MNC component +1 bit (for the p-bit)); 
         [0028]    At step  254 , if the δ MCC-1,n  differs from the previous delta δ MCC-1,(n−1) , the presence bit is set to 1, the delta value δ MCC-1,n  is stored into a field of length ┌Log 2  δ MCC-1,n−1┐ if ( Log   2  δ MCC-1,(n−) ) is not an integer, otherwise the delta value is stored into a field of length ┌Log 2  δ MCC-1,n− ┐+1 and the rest of the PLMN-ID (the MNC component) is stored in a corresponding additional field (the total field length will be ┌Log 2  ≡ MCC-1,n−1 ┐ bits if (Log 2  δ MCC-1,(n−1) ) is not an integer, otherwise the total field length will be ┌Log 2  δ MCC-1,n−1 ┐+1 bits, + the length required to store the MNC component +1 bit (for the p-bit)). At step  270 , after the entire list has been processed, the PLMN-IDs are transmitted to one or plurality of mobile devices (WTRUs, mobile phones or other mobile devices, etc.). 
         [0029]    Table 3 displays an example of the multiple PLMN-ID list (without the MNC component) when no zero-deltas exist between any MCCs and the MCC-1. 
         [0000]    
       
         
               
             
               
               
               
             
           
               
                 TABLE 3 
               
             
             
               
                   
               
               
                 Offset Field Reduction format with no zero-deltas 
               
               
                 (without p-bit or MNC) 
               
             
          
           
               
                 Field value 
                 Field length 
                 Comment 
               
               
                   
               
               
                 MCC-1 
                 10-bit 
                 Greatest MCC value (No p-bit is 
               
               
                   
                   
                 needed for the first entry) 
               
               
                 δ MCC-1, 2   
                 ┌Log 2  MCC-1┐ if 
                 Presence bit (p-bit) exists and set 
               
               
                   
                 Log 2  MCC-1≠ integer, 
                 (= 1). 
               
               
                   
                 else ┌Log 2  MCC-1┐ +1 
                 If p-bit set, then MCC-2 = 
               
               
                   
                   
                 MCC-1 − δ MCC-1, 2  ; 
               
               
                 δ MCC-1, 3   
                 ┌Log 2 δ MCC - 1,2 ┐if 
                 P-bit = 1; MCC-3 = MCC-1 − 
               
               
                   
                 Log 2  δ MCC-1, 2  ≠ integer, 
                 δ MCC-1, 3  ; 
               
               
                   
                 else ┌Log 2 δ MCC - 1,2 ┐+1 
               
               
                 ; ; ; 
                   
                 P-bit = 1; MCC-3 = MCC-1 − 
               
               
                   
                   
                 δ MCC-1, 3  ; 
               
               
                 δ MCC-1, n   
                 ┌Log 2 δ MCC - 1,n − 1 ┐ if 
                 MCC-n = MCC-1 − δ MCC-1, n   
               
               
                   
                 Log 2  δ MCC-1,(n−1) ≠ 
               
               
                   
                 integer, else 
               
               
                   
                 ┌Log 2 δ MCC - 1,n − 1 ┐+1 
               
               
                   
               
             
          
         
       
     
         [0030]    The following is an example of multiple PLMN-ID (without the MNC component) list compression when a zero-delta exists between MCC-2 and MCC-1. The virtual representative of MCC-2 (i.e. the P-bit=0, see Table 4) is inserted between the MCC-1 and the MCC with the largest delta to MCC-1 (note the usage of the presence bit P-bit in the example). The p-bit rule for this method is as follows: if the p-bit right after MCC-1 is not set, then MCC-2==MCC-1, and so on, until the first p-bit is set. The field length is now ┌Log 2  MCC-1┐ if Log 2  MCC-1 is not an integer, otherwise the field length is ┌Log 2  MCC-1┐+1, plus the p-bit. Store δ MCC-1,n  into a field of length ┌Log 2  δ MCC-1,n−1 ┐ if (Log 2  δ MCC-1,(n−1) ) is not an integer, otherwise store δ MCC-1,n  into a field of length ┌Log 2  δ MCC-1,n−1 ┐+1, plus the p-bit. 
         [0000]    
       
         
               
             
               
             
           
               
                 TABLE 4 
               
             
             
               
                   
               
               
                 Offset Field Reduction format with zero-deltas (without MNC or p-bit) 
               
             
          
           
               
                 
                   
                             
                     
                         
                         
                     
                   
                 
               
               
                   
               
               
                 
                   
                             
                     
                         
                         
                     
                   
                 
               
               
                   
               
               
                 
                   
                             
                     
                         
                         
                     
                   
                 
               
               
                   
               
               
                 
                   
                             
                     
                         
                         
                     
                   
                 
               
               
                   
               
               
                 
                   
                             
                     
                         
                         
                     
                   
                 
               
               
                   
               
             
          
         
       
     
         [0031]    In Table 4, row 4 demonstrates that when the P-bit=0, MCC-3 and MCC-4 have the same MCC value and therefore the same delta value with respect to MCC-1. An example would be MCC-1=866, MCC-2=866, MCC-3=502, MCC-4=502. So with respect to MCC-1, the δ MCC-1,2 =0, the δ MCC-1,3 =364, the δ MCC-1,4 =364. So both deltas are equal to  384  (not zero). But the two deltas (364 vs. 364) are equal, so we can take advantage of this fact to further reduce multiple (with equal MCCs) PLMN-ID transmission by setting the p-bit=0. This instructs the mobile device (WTRU, mobile phone, etc.) to use the previous delta value, in deriving the MCC for this particular delta value, as shown in Table 5, row 4, below (in actual transmission, only Presence-bit is transmitted to the mobile device; the field length equal to zero (0) is derived by the rules previously set forth above): 
         [0000]    
       
         
               
             
           
               
                 TABLE 5 
               
               
                   
               
               
                 
                   
                             
                     
                         
                         
                     
                   
                 
               
               
                   
               
             
             
               
                 
                   
                             
                     
                         
                         
                     
                   
                 
               
               
                   
               
               
                 
                   
                             
                     
                         
                         
                     
                   
                 
               
               
                   
               
               
                 
                   
                             
                     
                         
                         
                     
                   
                 
               
               
                   
               
               
                 
                   
                             
                     
                         
                         
                     
                   
                 
               
               
                   
               
             
          
         
       
     
         [0032]    Given that certain methods, as set forth above, are applicable to particular combinations of PLMN-IDs and that the PLMN-IDs for network sharing in LTE are not often changed, the E-UTRAN may pre-test the PLMN-IDs using different compression methods, as set forth above, and publish the PLMN-IDs in the most efficient method appropriate to the given PLMN-IDs combinations. The E-UTRAN could announce the compression method (using a method indicator) in the system information block (SIB) broadcast together with the compressed multiple PLMN-IDs, so that the WTRUs in the cell know how to decode the network sharing PLMN-IDs. 
         [0033]    Given that a MCC is unique, and given that there are less than 256 countries represented in the MCC lists, many values in the 3-digit MCC value range are not used. Therefore the MCC 3-digit value may be remapped into a new-MCC-entry-list of 256 or less, for example, 128, world-wide. Further, if that list can be divided by continent, then for each continent-MCC-entry-list, less that 128 values can be used. 
         [0000]    
       
         
               
             
               
               
               
             
               
               
             
           
               
                 TABLE 5 
               
             
             
               
                   
               
               
                 Remap the MCC value to an Entry List 
               
             
          
           
               
                 Entry- 
                 Original MCC 
                   
               
               
                 Index 
                 Value 
                 Comment 
               
               
                   
               
             
          
           
               
                 0 
                 MCC value 127 
               
               
                 1 
                 MCC value 135 
               
               
                 2 
                 MCC value 354 
               
               
                 3 
                 MCC value 788 
               
               
                 ;; 
               
               
                 127  
                 MCC value ??? 
               
               
                   
               
             
          
         
       
     
         [0034]    The MCC values may be remapped to an Entry-List. In the multiple PLMN-ID list transmission, only the relevant Entry-Indexes may be used. 
         [0035]    The same principles as described above equally apply to the MNC component of the PLMN-ID, i.e. the MNC may be similarly remapped into another entry-list and only the relevant MNC entry-index will be used in conjunction with the MCC entry-index for the transmission of multiple PLMN-IDs. 
         [0036]    The aforementioned remapping methods may also be used in conjunction with the field length reduction techniques described above. 
         [0037]    The aforementioned methods may be implemented in a variety of hardware devices. One implementation is in a an evolved Node-B (eNB)  300  shown in  FIG. 3 . The eNB  300  contains a compressor  310  and a transmitter  320 . The eNB  300  obtains a list (typically from the network or a component of the network) of PLMN-IDs. The PLMN-IDs are passed to the compressor  310  which compresses one or both of the components of the PLMN-ID (MCC and MNC) according to the aforementioned techniques. The compressor  310  contains a processor  312 , a sorter  314 , a formatter  316  and an arranger  318 . The processor  312  performs a variety of calculations and manipulation of PLMN-ID components and data. The sorter  314  sorts PLMN-ID components and data in ascending or descending order. The formatter  316  stores PLMN-ID components and data, into lists, tables, and any other data structure. These lists, tables, and any other data structures may reside in volatile memory, nonvolatile memory or any other type of storage device. The arranger  318  is configured to arrange PLMN-ID components and data, moving such information around within and among the previously described data structures (or within a new data structure). 
         [0038]      FIG. 4  illustrates an example of a wireless network  400  made up of WTRUs  420 ,  430 ,  440 ,  450  and an evolved Node B (eNB)  460  with the eNB&#39;s coverage area  410  being illustrated. WTRUs generally include various components such as a transmitter component  420   T , a receiver component  420   R , a processor component  420   P  and a memory component  420   M  which are illustrated with respect to WTRU  420 . In this example, eNB  460  processes the PLMN-ID list according to the aforementioned methods and transmits a message containing an indication of the compression method and the compressed PLMN-ID list to any MD that requires the list such as MD  420 . MD  420  receives the message containing the compression method indicator and compressed PLMN-ID list in its receiver  420   R  and then the MD  420  processor  420   P  stores the compressed PLMN-ID list into its memory  420   M  and uses the compression indicator to “decode” the compression list. 
         [0039]    Although the features and elements of the present invention are described in the preferred embodiments in particular combinations, each feature or element can be used alone without the other features and elements of the preferred embodiments or in various combinations with or without other features and elements of the present invention. The methods or flow charts provided in the present invention may be implemented in a computer program, software, or firmware tangibly embodied 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). 
         [0040]    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. 
         [0041]    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) module.