Abstract:
A mobile unit deployed in a wireless telecommunications system includes a network mute feature. Activation of the network mute feature initiates a signaling protocol in which a network mute activation request is extended by the mobile unit to a serving base station. Deactivation of the network mute feature also requires the mobile unit to generate a signal which is extended to the serving base station. Advantageously, the network mute feature not only mutes the microphone of the mobile unit but also eliminates disruptive noise associated with wireless transmissions.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is related to the application of Alex Lawrence Wierzbicki and Randall Joe Wilson entitled “Network Mute Feature In Wireless Telecommunications Systems” which application is assigned to the assignee of the present application and which is being filed concurrently herewith. 
     TECHNICAL FIELD 
     This invention relates to telecommunications systems, and more particularly to the mute function associated with mobile units deployed in wireless telecommunications systems. 
     BACKGROUND OF THE INVENTION 
     The explosive growth of wireless telecommunications is evidence of modem society&#39;s expectation for almost instantaneous access to information. The decreased cost associated with wireless (mobile) handsets and the enhanced reliability of wireless transmissions has made mobile telecommunications a viable option for almost everyone. Indeed, it is now common for mobile subscribers to use wireless telecommunications services for all types of transactions. Traditional voice and data transmissions (e.g., facsimiles) are commonplace for even unsophisticated mobile subscribers. For others (e.g., those subscribers who conduct business via their mobile units), wireless telecommunications serves as a lifeline to customers and the office. 
     A well known staple of the business world is the conference call. A conference call is a meeting in which typically one or more parties participates in the discussion via telephone. As more business people travel and conduct their lives from airports and automobiles, it is becoming increasingly common for at least one conference call participant to be using a mobile unit served by a wireless telecommunications network. Although improvements have been made, the quality of a conference call is often a deterrent to a successful meeting. The less-than-optimal quality of a conference call, coupled with the ambient background noise associated with transmission by a wireless telecommunications network, is sometimes so intolerable that mobile conference call participants are asked to drop off from the call so that the rest of the participants may discuss matters with decreased distraction. Although most mobile units have a “mute” function, this function only deactivates the microphone of the mobile unit. Ambient noise associated with wireless transmission still flows to the other party via the wireless telecommunications network. 
     For the foregoing reasons, there is a need in the art to enhance the ability of a mobile user to participate in a conference call. 
     SUMMARY OF THE INVENTION 
     This need has been addressed and a technological advance is achieved in the wireless telecommunications art by a network mute feature on a mobile unit. 
     More particularly, a network mute function button is found on a mobile unit. Typically, the network mute function is used by a mobile user during participation in a conference call in which the other parties participating in the call are subject to the ambient noise associated with the mobile user&#39;s environment and the wireless telecommunications network. Activation of the network mute function causes the mobile unit to send a signaling message to the mobile switching center which decouples a voice path interconnecting the mobile user to another party. The mobile switching center subsequently interconnects the voice path to a noise generator. The noise generator provides non-obtrusive background noise which is heard only by the other party. The purpose of the background noise is to assure the other party that the mobile user is still on the line and can hear the conversation. 
     Advantageously, the network mute function actually mutes the mobile unit microphone and noise associated with the wireless telecommunications systems. In other words, the network mute function not only mutes the microphone with the mobile unit but also eliminates wireless network noise associated with the wireless telecommunications system interconnecting the mobile user to another party. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIGS. 1A and 1B are simplified block diagrams of a wireless telecommunications system in which the present invention may be practiced; 
     FIG. 2A is a front view of a typical mobile handset with mute function; 
     FIG. 2B is a simplified block diagram of the internal components of the mobile handset shown in FIG. 2A; 
     FIG. 3 is a flow diagram depicting the steps performed by a mobile handset for activating a network mute function; 
     FIG. 4 is a flow diagram depicting the steps performed by a wireless telecommunications system for activating a network mute function; 
     FIG. 5 is a flow diagram depicting the steps performed by a wireless telecommunications system for dial access code activation of a network mute function; and 
     FIG. 6 is a flow diagram depicting the steps performed by a wireless telecommunications system for deactivation of a network mute function. 
    
    
     DETAILED DESCRIPTION 
     FIG. 1A shows wireless telecommunications system  100  including mobile unit  110 , base station  120  and mobile switching center  140 . Also shown is public switched telephone network (PSTN)  180  which serves all other wireline and wireless subscribers. 
     In this example, mobile unit  110  (including network mute button  113 ) is served by base station  120 . Base station  120  includes processor  122  interconnected to air interface  123 , radio resource interface  124  and database  126  via links  121 ,  125  and  127 , respectively. Also shown is antenna  128  interconnected to air interface  123  via link  131 . Air interface  123  is interconnected to radio resources  124  via link  133 . 
     Mobile switching center (MSC)  140  comprises controller  142  interconnected to announcement/tone generation circuit  160  via link  141 . Timeslot interchanger (TSI)  144  is interconnected to the controller via link  143 . Also shown are voice decoder  146  and noise generator  148  interconnected to TSI  144  via voice paths. 
     During operation, voice paths are established from radio resources  124  through TSI  144  to PSTN  180 . In this example, non-muted voice paths  151 ,  153  are shown emanating from radio resource interface  124 , passing through voice decoder  146  and terminating at PSTN  180 . More particularly, voice path  151  interconnects the mobile user to the called party served by the PSTN while voice path  153  interconnects the called party to the mobile user. Alternatively, voice paths  151 ,  153  could have been shown as a single bidirectional voice path. Voice decoder  146  is used in digital wireless systems (e.g., CDMA or TDMA systems) for processing the normally compressed voice signals received. The voice decoder decompresses the voice signals and converts these signals to a pulse code modulation format recognizable by the PSTN. Significantly, voice decoder  146  is not present in analog wireless telecommunications systems. Also shown is network me voice path  155  and its counterpart voice path  157 . In this case, voice path  155  (from the mobile user to the called party) emanates from radio resource interface  124 , passes through voice decoder  146  and is opened prior to connection to the called party served by the PSTN. The remaining portion of voice path  155  (that is, the portion of the path still interconnected to the called party) is interconnected to link  149 . Link  149 , emanating from noise generator  148 , is interconnected to voice path  155  so that non-obtrusive background noise is supplied to voice path  155  by the noise generator before termination to the called party. By opening voice path  155  within TSI  144 , the ambient noise associated with the mobile user&#39;s environment and wireless transmission is not passed to the called party served by the PSTN. Instead the called party hears non-obtrusive background noise so that the called party is aware that the mobile user is still on the line without being subject to the disturbances associated with wireless transmission. Significantly, voice path  157  interconnecting the called party to the mobile user is not opened. In other words, the mobile user can hear all conversation initiated by the called party. 
     FIG. 1B shows an alternative embodiment for TSI  144 , voice decoder  146  and noise generator  148 . In this embodiment, the noise generator is disposed within the voice decoder. In this example, first leg  175  of a network muted voice path terminates in voice decoder  146  while second leg  177  of the network muted voice path emanates from noise generator  148  and terminates to the called party. Voice path  179  interconnecting the called party to the mobile unit is not affected by the network mute function. In other words, the mobile unit user is able to hear all transmissions originated by the called party. 
     FIG. 2A shows a front view of a typical mobile unit  200 . Mobile unit  200  comprises visual display screen  202 , antenna  204 , a plurality of function buttons, collectively referenced as function buttons  206 , and mute network function button  208 . 
     FIG. 2B shows the internal components of mobile unit  200  shown in FIG.  2 A. More particularly, mobile unit  200  comprises processor  210  interconnected to memory  212  via link  213 . Radio frequency receiver  214 , dual tone multifrequency (DTMF) tone generator  216  and signal generator  218  are shown interconnected to the processor via links  215 ,  217  and  219 , respectively. Processor  210  is responsible for administering and managing all functions of the mobile unit. Radio receiver  214  receives radio frequency signals via antenna  204 . DTMF tone generator  216  is interconnected to function buttons  206  for generating a specific DTMF tone for each button. DTMF tone generator  216  is also interconnected and generates a particular DTMF tone for network mute function button  208 . Signal generator  218  extends radio frequency signals from the mobile unit to the PSTN via antenna  204 . Memory  212  stores data associated with mobile unit  200 . 
     In the preferred embodiment, memory  212  includes memory segment  220  which stores a signaling protocol relating to operation of network mute function button  208 . More particularly, the signaling protocol stored in segment  220  is accessed by processor  210  upon receipt of a network mute request. When the network mute button is activated, processor  210  extends a network mute request to a serving mobile switching center (via a base station) in an established signaling format such as IS 95, “blank and burst” signaling or IS 136. 
     FIG. 3 is a flow diagram depicting the steps performed in a mobile unit for activation of the network mute function. The process begins in step  300  in which the user of the mobile unit activates the network mute feature by depressing a mute button. In step  302 , a DTMF tone corresponding to the network mute function is received in the processor of the mobile unit. In mobile unit  200 , DTMF tone generator  216  generates a specific tone associated with network mute function button  208  and extends this specific tone to processor  210  over link  217 . In step  304 , the processor receives the mute request and accesses its memory to retrieve a signaling protocol associated with the network mute function. In this example, processor  210  accesses memory segment  220  for the network mute signaling protocol. In step  306 , processor  210  instructs signal generator  218  to extend a network mute request signal to a serving base station. The network mute request signal is extended to the serving base station via a radio frequency protocol such as IS 95, IS 136, “blank and burst” signaling or direct transfer application part (DTAP) signaling. 
     FIG. 4 is a flow diagram depicting the steps performed in a wireless telecommunications system for activation of the network mute function. For purposes of example, assume that the network mute function is activated in wireless telecommunications system  100 . 
     The process begins in step  400  in which a base station receives a network mute request signal from a mobile unit and extends this request to its serving mobile switching center. In this example, base station  120  receives a network request mute signal and extends it to MSC  140 . In step  402 , MSC  140  receives the network mute request. If the mobile user is roaming, standard inter-MSC handoff signaling is used to ensure that the serving MSC receives the network mute request from the mobile user. 
     The process continues to decision step  404  in which the MSC determines whether the ongoing call is an emergency (e.g., E911) call. If the outcome of decision step  404  is a “YES” determination, the process continues to step  405  in which the network mute request is denied and the MSC issues a tone or announcement to the mobile user indicating such. If the outcome of decision step  404  is a “NO” determination, the process continues to step  406  in which the MSC determines whether the noise generator is available to handle the newly received network mute request. MSC  140  checks on the status of the noise generator because these resources are intentionally limited to minimize space requirements. If the outcome of decision step  406  is a “NO” determination, the process returns to step  405  in which the MSC denies the network mute request and issues an announcement or tone to the mobile user via announcement/tone circuit  160 . For example, the announcement or tone issued to the mobile user via serving base station  120  may indicate that the network mute function is not available but that the user may try again at a later time. If the outcome of decision step  406  is a “YES” determination, the process continues to step  408  in which the MSC opens the voice path from the mobile unit to the PSTN (or the called party) but holds the voice path resources. In the same step, the MSC activates a path from a portion of the open voice path to a noise generator for the insertion of non-obtrusive background noise to be played to the called party. The process continues to step  410  in which a network mute activated message or tone is issued to the mobile user via the announcement/tone circuit for indicating that the network mute function has been turned “on” and will remain active until the user elects to deactivate the function. Alternatively, a network mute signal may be visually displayed on the mobile unit. 
     FIG. 5 is a flow diagram depicting the steps performed in a wireless telecommunications system in which the network mute function is activated by a dial access code. A dial access code is a predetermined set of signals (e.g., *77) which indicates to the wireless telecommunications system that a mobile unit user wishes to invoke the network mute feature. 
     Dial access code activation of a network mute feature begins in step  500  in which the serving MSC receives a dialed access code from a mobile user. This particular access code identifies activation of a network mute function. In step  502 , the MSC recognizes the access code as the network mute request. The process continues to decision step  504  in which the MSC determines if the ongoing call is an E911 call. If the outcome of decision step  504  is a “YES” determination, the process continues to step  505  in which the network mute function request is denied. An announcement or tone from circuit  160  is issued to the mobile user to indicate the denial. If the outcome of decision step  504  is a “YES” determination, the process continues to decision step  506  in which the MSC determines if a noise generator is available to satisfy the network mute request. If the outcome of decision step  504  is a “NO” determination, the process returns to step  505  in which the network mute request is denied and an announcement or tone indicating such is issued to the mobile user. If the outcome of decision step  506  is a “YES” determination, the MSC opens the voice path interconnecting the mobile user to a called party served by the PSTN but holds the voice path resource. After opening the voice path to the called party, the called party is interconnected to a path associated with a noise generator. During activation of a network mute function, the called party does not hear ambient noise associated with the environment of the mobile user or wireless telecommunications transmission. Instead, the called party hears an unobtrusive background noise indicating that the mobile user is still on the call and can hear transmissions from the called party. The process ends in step  508  in which activation of the network mute function is confirmed by issuing an announcement or tone to the mobile user. 
     FIG. 6 shows a flow diagram of the steps required in a wireless telecommunications system to deactivate the network mute function. The process begins in step  600  in which the MSC receives a deactivate signal or deactivate dial access code associated with the network mute function. In step  602 , the MSC recognizes the deactivate signal and releases the link from the voice path to the noise generator. In step  604 , the MSC reconnects the previously opened voice path to the called party. In other words, this step, the MSC reestablishes a voice path as if the network mute function was not in effect. Simultaneously, in step  606 , the MSC extends a mute deactivated announcement or tone to the mobile user. 
     Advantageously, implementation of the network mute feature in a wireless telecommunications system allows a mobile user to truly eliminate the ambient noise associated with the environment of the mobile unit and wireless telecommunications transmission. This feature may be deployed whether the mobile user is the calling or called party. Although this invention has been described with respect to a preferred embodiment, those skilled in the art may devise numerous other arrangements without departing from the scope of the invention as defined in the following claims.