Abstract:
A wireless terminal dynamically positions itself into a call pickup group based on the location of the wireless terminal. Similarly, a wireless terminal dynamically removes itself from a call pickup group on the basis of the location of the wireless terminal. A wireless terminal can be excluded from joining a call pickup group in a specific location. The wireless terminal positions itself into the call pickup group by communicating information with other wireless terminals already in the call pickup group. This communication is controlled by a controlling wireless terminal with which the wireless terminal first communicates upon entering the location. The wireless terminal determines its position by communication with a fixed unit assigned to the location of call pickup group. Upon determining that it is leaving the location, the wireless terminal transmits a message to controlling wireless terminal to inform it of this fact. In turn, the controlling wireless terminal transmits messages to the other wireless terminals to inform them of the departure of the wireless terminal.

Description:
TECHNICAL FIELD 
     This invention relates generally to wireless switching systems and, in particular, to telephone call management within such a system. 
     BACKGROUND OF THE INVENTION 
     When a number of telephones are situated in a common open area, a situation often arises where the user of one of the ringing telephones does not answer. It is highly desirable for another individual within the area to utilize their own telephone to answer the incoming call for the other telephone. Within the prior art this has been accomplished by placing the telephones within the common area into a call pickup group. If a first telephone within the call pickup group is being rung, a user of a second telephone of the call pickup group can actuate a designated button on their telephone or dial a special code to answer the call that is directed to the first telephone. 
     The prior art pickup groups have functioned well with wired telephone sets. Such pickup groups are manually administered on the telecommunication switching system providing service for the telephones within the pickup group. In particular, the prior art pickup groups and their administration have functioned well for the traditional business environment where an employee is assigned a desk or a specific location and performs their principle work function at that telephone or location. The traditional environment is slowly changing. In the emerging business environment, individuals do not have a wired telephone but rather they have a wireless telephone that they carry with them at all times and that is their only telephone. In addition, employees during the course of a day perform many functions at different locations. 
     SUMMARY OF THE INVENTION 
     The foregoing problems are solved, and a technical advance is achieved by an apparatus and method in which a to wireless terminal dynamically positions itself into a call pickup group based on the location of the wireless terminal. Similarly, a wireless terminal dynamically removes itself from a call pickup group on the basis of the location of the wireless terminal. Advantageously, a wireless terminal can be excluded from joining a call pickup group in a specific location. The wireless terminal positions itself into the call pickup group by communicating information with other wireless terminals already in the call pickup group. Advantageously, this communication is controlled by a controlling wireless terminal with which the wireless terminal first communicates upon entering the location. The wireless terminal determines its position by communication with a fixed unit assigned to the location of call pickup group. Upon determining that it is leaving the location, the wireless terminal transmits a message to controlling wireless terminal to inform it of this fact. In turn, the controlling wireless terminal transmits messages to the other wireless terminals to inform them of the departure of the wireless terminal. 
     Other and further aspects of the present invention will become apparent during the course of the following description and by reference to the accompanying drawing. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     FIG. 1 is a block diagram of a wireless system for implementing the invention; 
     FIGS. 2-7 illustrate Table 1 that is maintained by a wireless switching system in implementing the invention; 
     FIG. 8 illustrates, in block diagram form, a fixed unit; 
     FIG. 9 illustrates, in block diagram form, a wireless terminal; 
     FIG. 10 illustrates, in flow chart form, steps performed by a fixed unit; 
     FIGS. 11-15 illustrate, in flow chart form, steps performed by a wireless terminal; and 
     FIG. 16 illustrates the format of a transceiver alert message. 
    
    
     DETAILED DESCRIPTION 
     FIG. 1 illustrates, in block diagram form, a wireless system for implementing the invention. Wireless switching system  101  via base stations  121 - 122  provides wireless service for wireless terminals  102 - 109  that are free to roam throughout cubicle areas  112 - 114 . Wireless terminals  102 - 109  determine which cubicle area they are in by receiving transmissions from the fixed unit located in each of these areas. Each fixed unit transmits at predefined intervals the identification of the fixed unit via a different transmission medium than utilized by the base stations  121 - 122 . This transmission medium may be an infrared transmission. Wireless terminals  102 - 109  have a receiver for receiving the infrared transmission from the fixed units. When a wireless terminal receives the identification code from a fixed unit, the wireless terminal then utilizes the identification code to access an internal table to determine operations with respect to that fixed unit. FIGS. 2-7 illustrate Table 1 which is accessed with the identification of the fixed unit. One skilled in the art could readily see that other methods could be utilized to determine the location of a wireless terminal. For example, global positioning satellite (GPS) devices or base stations could be used to determine a position of a wireless terminal. 
     In accordance with the invention, it is possible to establish a call pickup group based on the location of the wireless terminals. To understand this operation, consider the following example. A call pickup group is established for cubicle areas  113  and  114  but not for cubicle area  112 . In addition, as will be explained later in greater detail, it is possible for a wireless terminal to be marked in Table 1 indicating that when the wireless terminal enters a cubicle area having a call pickup group that the marked wireless terminal will not become part of this group. At the start of the example, the wireless terminals are in the cubicle areas as illustrated in FIG.  1 . FIGS. 2 and 3 illustrate Table 1 for wireless terminal  106 , FIGS. 4 and 5 illustrate Table 1 for wireless terminal  104 , and Tables 6 and 7 illustrate Table 1 for wireless terminal  108 . FIGS. 2,  4 , and  6  illustrate the contents of Table 1 for each of these wireless terminals when the wireless terminals are in the positions as illustrated in FIG.  1 . In any given area, one wireless terminal is the controlling wireless terminal with respect to controlling the transfer of data between wireless terminals within that area. The controlling wireless terminal is determined by the wireless terminal in the area having the largest telephone number. One skilled in the art could readily envision that other algorithms could be utilized to determine the controlling wireless terminal. 
     For example, the controlling wireless terminal could be the terminal that had been in the area for the longest period of time. In addition, the controlling wireless terminal could be designated by a predefined priority scheme. For example, FIG. 2 illustrates that the controlling wireless terminal in cubicle area  113  is wireless terminal  106 . This fact is indicated by a 1 in column  205  of FIG. 2 for wireless terminal  106 . Also, FIG. 2 indicates that Table 1 is the table for wireless terminal  106  by the entry of a 1 in column  203  on the same line as the entry of wireless terminal  106  in column  201 . Column  206  indicates with which fixed unit a wireless terminal is in communication. Further, each of the fixed unit has an assigned telephone number that is unique to the fixed unit and to which wireless terminals in communication with the fixed unit will respond unless a 1 is entered into column  204  indicating an excluded fixed unit. Note, that in FIG. 2, only fixed unit  117  is marked as being an excluded fixed unit. FIG. 4 illustrates Table 1 for wireless terminal  104  and indicates that the controlling wireless terminal is wireless terminal  106 . Table 1 of FIG. 4 also indicates in column  403  of FIG. 4 that the telephone number for wireless terminal  104  is 2804. FIG. 6 illustrates Table 1 for wireless terminal  108  and defines that wireless terminal  109  is the controlling wireless terminal of the pickup group for fixed unit  116  located in cubicle area  114 . 
     If an incoming call is received by wireless switching system  101  for wireless terminal  106 , wireless switching system  101  broadcasts a page message specifying telephone number 2806. Wireless terminal  106  is responsive to this paging message to generate an alerting signal. This determination is made by examining column  202  of FIG.  2 . Wireless terminals  104  and  105  respond to this paging message by indicating that a wireless terminal that is part of the call pickup group is generating an alerting signal. Similarly, if wireless switching system  101  generates a page message for telephone number 2903 which is assigned to fixed unit  115 , wireless terminals  104 - 106  each generate an alerting signal. One skilled in the art could readily see that an alerting signal could only be generated by one of the wireless terminals selected by a predefined algorithm such as length in communication with the fixed unit or having the highest or lowest telephone number of the wireless terminals in communication with the fixed unit. The entries in Table 1 corresponding to the fixed units are preloaded into a wireless terminal via wireless switching system  101 , manually loaded, or down loaded by attaching the wireless terminal to a computer not illustrated. The information in Table 1 pertaining to wireless terminals other than the information pertaining to the wireless terminal in the table of the storing wireless terminal is added or subtracted as a wireless terminal comes in contact with a fixed unit. When a wireless terminal loses contact with the fixed unit with which it is presently communicating, it transmits to the controlling wireless terminal the fact that it is no longer in contact with the fixed unit. The controlling wireless terminal then informs the other wireless terminals of the pickup group. If the departing wireless terminal is the controlling wireless terminal, it transmits to the wireless terminal having the is next highest telephone number the fact that it has lost contact with the fixed unit. When a wireless terminal comes in contact with a new fixed unit, it transmits a transceiver alerting message directed to a reserved predefined telephone number. The controlling wireless terminal in the new pickup group responds to this message with a data call to the new wireless terminal and informs the new wireless terminal of the other wireless terminals in the pickup group. After the necessary information has been obtained from the new wireless terminal, the controlling wireless terminal transmits this information to the other wireless terminals in the pickup group. If the new wireless terminal has a higher priority than the current controlling wireless terminal, then the new wireless terminal becomes the controlling wireless terminal. If the transceiver alert message is not responded to by a controlling wireless terminal, the new wireless terminal assumes that it is the only wireless terminal in the pickup group for this fixed unit and designates itself as the controlling wireless terminal. As each wireless terminal in a pickup group receives information concerning a new wireless terminal from the controlling wireless terminal, each wireless terminal makes the necessary updates to its Table 1. 
     To further understand how Table 1 for each wireless terminal is modified by the addition or loss of a wireless terminal to a pickup group consider the following example. Wireless terminal  106  leaves area  113  losing contact with fixed unit  115  and moves to area  114  establishing contact with fixed unit  116 . When wireless terminal  106  determined that it has lost contact with fixed unit  115 , it established a data call to wireless terminal  105  and informed it that wireless terminal  105  is the new controlling wireless terminal for the pickup group for fixed unit  115 . Wireless terminal  105  makes the necessary adjustments to its Table 1 and transmits the fact that wireless terminal  106  is no longer part of the group to wireless terminal  104 . FIG. 5 indicates that wireless terminal  104  modifies Table 1 to delete reference to wireless terminal  106  and to indicate that wireless system  105  is the controlling wireless terminal by entry of a 1 in column  505  of FIG.  5 . Note, if wireless terminal  106  is unable to establish a data call to wireless terminal  105 , wireless terminal  105  realizes that wireless terminal  106  has departed from the pickup group when it does not receive a periodic data call from wireless terminal  106 . The controlling wireless terminal periodically establishes data calls to the other wireless terminals of the pickup group so that these other wireless terminals can ascertain that the controlling wireless terminal is still present and so that the controlling wireless terminal can ascertain that the other wireless terminals are still present. 
     Continuing with the example, when wireless terminal  106  comes in contact with fixed unit  116 , wireless terminal  106  transmits a transceiver alert message. Wireless terminal  109 , the controlling wireless terminal for the pickup group for fixed unit  116 , responds to this transceiver alert message in accordance with the protocol and establishes a data call to wireless terminal  106 . Via the data call, wireless terminal  109  transmits to wireless terminal  106  the identities of wireless terminals  107  and  108 . Wireless terminal  106  is responsive to this information to modify Table 1 as illustrated in FIG.  3 . Wireless terminal  108  is responsive to the information from controlling wireless terminal  109  to add wireless terminal  106  to Table 1 for wireless terminal  108  as illustrated in FIG.  7  and to transmit this information to wireless terminals  107  and  108 . 
     FIGS. 11-15 illustrate, in flow chart form, the steps performed by a wireless terminal. After being started, decision block  1101  determines if contact has been made with a new fixed unit. If the answer is yes, control is transferred to block  1100 . In block  1100 , the wireless terminal determines if on the previous fixed unit with which it was in communication whether or not it was part of a call pickup group. If the wireless terminal was part of a call pickup group, it informs the call pickup group of its departure. Note, if the wireless terminal was not the controlling wireless terminal of the former call pickup group, the departing wireless terminal simply transmits to the controlling wireless terminal the fact that it has departed from the call pickup group. However, if the wireless terminal was the controlling wireless terminal of the call pickup group from which it just departed, the wireless terminal informs the next highest priority wireless terminal of the call pickup group of its departure. The next highest priority wireless terminal will then establish itself as the controlling wireless terminal of the former call pickup group and inform the other wireless terminals of the departure. After execution of block  1100 , control is transferred to block  1102 . The wireless terminal establishes contacts with the present controlling wireless terminal by transmission of a transceiver alert message (illustrated in FIG. 16) in block  1102 . The present controlling wireless terminal responds to this message with a disconnect and then transmits a data call to the present wireless terminal. After execution of block  1102 , control is transferred to decision block  1103  which determines if the present wireless terminal is the new controlling wireless terminal. Note, that the transceiver alert message from the present controlling wireless terminal identified the telephone number of the present wireless terminal allowing the controlling wireless terminal to setup a data call. If no response is received to the transceiver alert message, the present wireless terminal executes block  1104 . If the present wireless terminal is the new controlling wireless terminal, which means that it has a higher priority than the current controlling wireless terminal, control is transferred to block  1104  which informs the other wireless terminals in the call pickup group that the present wireless terminal is now the controlling wireless terminal and obtains call pickup group data. Then, block  1106  updates Table 1 of the present wireless terminal before returning control to decision block  1101 . 
     If the present wireless terminal is not the new controlling wireless terminal, control is transferred from decision block  1103  to block  1107  which establishes contact with the controlling wireless terminal. Then, block  1108  receives the list and data of other wireless terminals in the call pickup group from the controlling wireless terminal, and block  1109  updates Table 1 of the present wireless terminal before returning control to decision block  1101 . 
     Returning to decision block  1101 , if communication has not been established with a new fixed unit, control is transferred to decision block  1201  of FIG.  12 . Decision block  1201  determines if the time has expired for the periodic check of the wireless terminals presently in a call pickup group. If the answer is yes, control is transferred to decision block  1202  which determines if the present wireless terminal is a controlling wireless terminal in a call pickup group. If the answer is yes in decision block  1202 , block  1203  transmits data calls to each of the other wireless terminals in the call pickup group. Decision block  1204  determines if any of these wireless terminals failed to respond to the data call. If the answer is no, control is transferred back to decision block  1101  of FIG.  11 . If the answer is yes in decision block  1204 , block  1206  updates the Table 1 of the present wireless terminals and transmits messages to the remaining wireless terminals in the call pickup group informing them of the missing wireless terminal before transferring control back to decision block  1101  of FIG.  11 . 
     If the answer in decision block  1202  is that the present wireless terminal is not the controlling wireless terminal of the call pickup group, control is transferred to decision block  1207 . The latter decision block determines if a periodic data call has been received. If the answer is yes, block  1208  transmits back an acknowledgment message before returning control to decision block  1101  of FIG.  11 . If the answer in decision block  1207  is no, it indicates that the controlling wireless terminal has left the call pickup group. Decision block  1209  determines if the present wireless terminal is the new controlling wireless terminal. If the answer is no, control is transferred back to decision block  1101  of FIG.  11 . If the answer is yes, block  1211  transmits the new configuration of the call pickup group to the other wireless terminals in the call pickup group, and block  1212  updates Table 1 for the present wireless terminal before transferring control back to decision block  1101  of FIG.  11 . 
     Returning to decision block  1201 , if the answer is no, control is transferred to decision block  1301  of FIG.  13 . Decision block  1301  determines if a transceiver alert message has been received from another wireless terminal. If the answer is yes, decision block  1302  determines if the present wireless terminal is the controlling wireless terminal for the call pickup group. If the answer is no, the present wireless terminal makes no response to the transceiver alert message but transfers control back to decision block  1101  of FIG.  11 . If the answer is yes in decision block  1302 , block  1303  transmits a disconnect message to the new wireless terminal, and block  1304  establishes a data call to the new wireless terminal. Decision block  1306  determines if the new wireless terminal is to be the new controlling wireless terminal of the call pickup group. If the answer is yes, block  1309  transmits the data of the wireless terminals in the call pickup group to the new wireless terminal and updates Table 1 of the present wireless terminal to reflect the new controlling wireless terminal before transferring control back to decision block  1101  of FIG.  11 . If the answer in decision block  1306  is no, block  1307  transmits the data of the wireless terminals in the call pickup group to the new wireless terminal, and block  1308  transmits data calls to the other wireless terminals of the call pickup group informing them of the data of the new wireless terminals and updates Table 1 of the present wireless terminal with the data of the new wireless terminal before transferring control back to decision block  1101  of FIG.  11 . 
     Returning to decision block  1301 , if the answer is no, control is transferred to decision block  1311 . If a data call has been received from the controlling wireless terminal with call pickup group data, the answer is yes in decision block  1311 . If the answer is yes, block  1312  updates Table 1 of the present wireless terminal with the new call pickup group data before returning control back to decision block  1101  of FIG.  11 . If the answer is no in decision block  1311 , control is transferred to decision block  1401  of FIG.  14 . 
     Decision block  1401  determines if a page has been transmitted by wireless switching system  101  for a group call pickup number. If the answer is yes in decision block  1401 , decision block  1402  determines if the page contains the telephone number of the wireless terminal. This would mean that a call is being directed to the wireless terminal. If the answer is yes, block  1403  generates an alerting signal on the wireless terminal and transfers control to block  1408 . Block  1408  responds to the page. Block  1409  then performs normal processing before transferring control back to block  1101  of FIG.  11 . If the answer in decision block  1402  is no, block  1404  indicates on the wireless terminal that a call is pending for a wireless terminal in the call pickup group before transferring control to decision block  1405 . The latter decision block determines if the wireless terminal has performed a call origination operation. If the answer is no, decision block  1406  determines if the pickup button has been actuated. If the answer is yes in decision block  1406 , control is transferred to block  1408  whose operations have already been described. If the answer is no in decision block  1406 , control is transferred back to decision block  1101  of FIG.  11 . If the answer in decision block  1405  is yes, decision block  1407  determines if the pickup access code has been dialed on the wireless terminal. If the answer is no, control is transferred back to decision block  1101  of FIG.  11 . If the answer is yes in decision block  1407 , control is transferred to block  1408  whose operations have been previously described. 
     If the answer in decision block  1401  is no, decision block  1502  of FIG. 9 determines if communication has been lost with the fixed unit. If the answer is yes, control is transferred to decision block  1507 . The latter decision block determines if the present wireless terminal is the controlling wireless terminal for the call pickup group. If the answer is no, control is transferred to block  1509  which transmits a message to the controlling wireless terminal for the call pickup group informing it that the present wireless terminal has left the call pickup group. If the answer is yes in decision block  1507 , block;  1508  transmits a message to the next highest priority wireless terminal in the call pickup group informing that wireless terminal that it is the new controlling wireless terminal. From either block  1508  or  1509 , control is returned to decision block  1101  of FIG.  11 . Returning to decision block  1502 , if the answer is no, block  1511  performs normal processing before returning control back to decision block  1101  of FIG.  11 . 
     FIG. 8 illustrates, in block diagram form, a fixed unit. The fixed unit of FIG. 8 is powered by battery  801 . However, one skilled in the art could readily see that normal building AC power could also be utilized to power the fixed unit. Controller  803  periodically transmits the identification code for the fixed unit via transmitter  804 . Advantageously, transmitter  804  can be transmitting utilizing infrared transmission or ultrasonic transmission. Transmitters for transmitting either infrared or ultrasonic are well known in the art. If controller  803  detects that battery  801  is at a low power level via conductor  807 , battery monitor  802 , and conductor  808 , controller  803  sets alarm indicator  805  and transmits the low power indication along with the identification code via transmitter  804 . 
     Wireless terminal  112  is illustrated in greater detail in FIG.  9 . Wireless terminal  112  implements a wireless protocol that allows wireless terminal  112  to maintain a wireless signal link with wireless switching system  101  via base stations  121 - 122 . One air interface that can be used is the Japanese PHS protocol as set forth in “User-Network Interface and Inter-Network Interface Standards for PHS”, the Telecommunication Technology Committee, 1995, and “Personal Handy Phone System RCR Standard”, Version 1, RCR STD-28, Dec. 20, 1993. The message set of the PHS protocol is similar to the ISDN message set. Overall control of the wireless terminal is provided by control unit  901 . Units  902 ,  903 ,  906 ,  907 ,  908 , and  909  provide the RF communication capabilities for the wireless terminal. Elements  904 ,  910 , and  911 - 914  provide the audio information received and transmitted to the user; whereas, elements  916 - 918  and  905  provide the basic user interface. The PHS protocol allows control unit  901  to establish a logical data channel with wireless switching system  101 . Control unit  901  utilizes this logical data channel to transmit identification information for fixed units to wireless switching system  101 . Fixed unit receiver  921  receives the identification code of a fixed unit and transfers this identification code to control unit  901  for transmission to wireless switching system  101 . Fixed unit receiver  921  is of a design well known in the art for either infrared or ultrasonic transmission media. One skilled in the art could readily see that fixed unit receiver  921  could provide to control unit  901  the signal strength of the received signal. Further, control unit  901  could also tune fixed unit receiver  921  to receive different frequencies or other variations of the transmission media using well known techniques in the art. 
     FIG. 10 illustrates the steps performed by a fixed unit. Decision block  1001  determines if it is time to transmit the identification code of the fixed unit. Advantageously, the identification code is transmitted every tenth of a second. If the answer is no, control is transferred back to decision block  1001 . If the answer is yes, decision block  1003  determines if battery monitor  1002  of FIG. 10 is indicating a low battery. If the answer is no, block  1004  simply transmits the identification code of the fixed unit before transferring control back to decision block  1001 . If the answer in decision block  1003  is yes, block  1006  transmits a message that includes the identification code and a low battery indication before transferring control back to decision block  1001 . 
     Of course, various changes in modification to the illustrated embodiment described above will be apparent to those skilled in the art. These changes and modifications can be made without departing from the spirit and scope of the invention and without diminishing its intended advantages. It is therefore intended that such changes and modifications be covered by the following claims.