Method and apparatus for monitoring link activity to prevent system deadlock in a dispatch system

Description: TECHNICAL FIELD [Detailed description of the invention]

Link activity to prevent system deadlock in the dispatch system How and equipment to squeeze Background of the invention I. Field of invention The present invention generally relates to a diapatch system and will be further specified. , Concerning the implementation of the dispatch system within the cellular system. II. Explanation of related technologies In radiotelephone communication systems, many users communicate on wireless channels And connect to other wireless and wired telephone systems. wireless channel Communication above may be one of a wide variety of multi-dimensional access techniques. this These multiple access techniques include time division multiple access (TDMA) and frequency division multiplexing. Includes Access (FDMA) and Code Division Multiple Access (CDMA). CDMA The technique has many advantages. An exemplary CDMA system, February 1990 Issued to K. Gilhousen et al. On the 13th, assigned to the assignee of the present invention, and participated. In light of this, "Spectra using satellite repeater or terrestrial repeater" Spread Multiplex Access Communication System (SPREAD SPECTRUM MULT) IPLE ACCESS COMMUNICATION SYSTEM USI NG SATELLITE OR TERRESTRIAL REPEATER Explained in US Pat. No. 4,901,307 entitled "S)". In the aforementioned patent, the majority of mobile phone systems, each with its own transceiver Satellite repeaters and aircraft that use CDMA spread spectrum communication signals Many that communicate through on-board repeaters or ground base station transceiver subsystems The original access technique is disclosed. Frequency spectrum when using CDMA communication Can be reused multiple times, allowing system users to increase capacity To. In a CDMA cellular system, each base station transceiver subsystem Provides scope to a limited geographic area and is remote within that range Link the device to the Public Switched Telephone Network (PSTN) via a cellular system switch. When the remote unit moves to the effective range of the new base station transceiver subsystem , The user's call routing is the new base station transceiver subsystem Transferred to. The signal transmission path from the base station to the remote device is called a forward link, and is far away. The signal transmission path from the remote device to the base station is called a reverse link. In a typical radiotelephone network, the remote device is voice in variable speed format. A bocoding system that encodes information may be used. Variable speed cis In the system, the data rate should be reduced due to pauses in voice activity. There is. The lower the data rate, the other you caused by remote device transmission. The level of interference with the user is reduced. In the base station, bocoding The stem is used to reconstruct the audio information. Data in addition to voice information Information alone, or a mixture of the two, may be transmitted by a remote device. When the remote device is creating its own data for transmission, the built-in vocoder is 20 Based on audio activity in milliseconds (ms) frames, for example, about 8,000 bits / Seconds (bps), 4,000bps, 2,000bps and 1,000bps Data encoded at four different speeds from a digital sample of audio information produce. Each frame of vocoder data is 9,600bps, 4,800bp Overs like s, 2,400bps, and 1,200bps data frames Formatted by the head bit. Equivalent to 9,600 bps frames The fastest data frame is called a "full rate" frame. 4,800 bps data frames are called "half-rate" frames. 2,400 Bps data frames are called "1/4 rate" frames. And A 1,200 bps data frame is called a "1/8 rate" frame. A vocoder suitable for use in this environment was published on May 9, 1995 and is a book. "VARIABLE RAT" transferred to the assignee of the invention Explained in U.S. Pat. No. 5,414,796 entitled "E VOCODER)" .. When the remote device receives data from an external source such as a terminal equipment unit, The remote device outputs the data in this variable speed frame format. Continue processing. The original cellular phone spectrum license was issued by the government When, one of the constraints on the use of spectra is that carriers are dispatchers. The point was that we could not provide the bis. However, of the CDMA system Significant benefits and inherent costs and issues of deploying and maintaining private dispatch systems Because of this, the government is reviewing this issue. The government itself has such a service Will greatly benefit from. Typical radiotelephone and wired services provide fixed-line services However, the dispatch service provides a one-to-many service. Dispatch service Common use of su is local police radio system, taxi courier system, federal search Operations of the Inspection Bureau and the Confidential Investigation Department, and general military communication systems. The basic model of the dispatch system is the user's broadcast network. It is composed of Each broadcast net user has one common browser Monitor the loadcast forward link signal. Internet users had a conversation If you want to, press the push-to-talk button and press the button. Stem Talker privilege is granted. Usually the sound of the sending user Voices are sent from the reverse link on the broadcast forward link. Ideally The dispatch system provides land and wireless access to the system. It will be possible. The remote device user releases the PTT button when the conversation ends. Response The remote device terminates its privileges and uses the system by other system users. Create a push-to-talk-off display to release for. When the push-to-talk button on the remote device stops and gets stuck (stuck) down), the remote device is granted system caller privileges. System resources (resou rce) was consumed in this way, and other remote devices stopped and stuck. Sith because a remote device with a swoosh-to-talk button is blocking the system You are prevented from accessing the system. This kind of scenario is a system deadlock Called (deadlock), not to mention this is a highly undesirable condition. Absent. The present invention detects a system deadlock and cuts off harmful effects on the body and mind. Methods and equipment for truncate. Outline of the invention When the remote device user presses the push-to-talk button, the communication manager System caller privileges can be granted to remote devices. Remote device makes a system call When he has personal privileges, his voice signal is a member of the dispatch system Broadcast to one other remote device. Remote device user push boots -When the talk button is released, the communication manager gains system caller privileges on the remote device. Deny, thus because other remote devices have system caller privileges Release the system. The push-to-talk button on the remote device stops and moves When it is gone, the remote device retains system caller privileges and thus other remotes. Prevents the device from obtaining a grant of system caller privileges. The present invention is a base station Monitor the audio activity of the signal received from the remote device. Level with constant voice activity Assuming that the remote device no longer requires system caller privileges below And the base station releases the push-to-talk button, which is sent to the communication manager Create a surrogate display to the effect that it has been done. In this way, communication money Ja is free to grant system caller privileges to another remote device. A brief description of the drawing The features, objectives and advantages of the present invention, when construed with the drawings, are as follows: It will become clearer from the detailed explanation given in. Figure 1 is a block diagram of a typical dispatch system. FIG. 2 is a floater showing an exemplary set of steps to achieve the present invention. It is Description of preferred embodiments Figure 1 shows a typical dispatch system. In a preferred embodiment , Remote devices 10, 20, 22 and 24 are both dispatch devices and two-point telephones Can function as a person. In Figure 1, remote device 10 is currently active The remote devices 20, 22, and 24 are currently passive listeners. Base station a Enters 30, 32, and 34 are broadcast forward links Channels may be provided to remote devices 20, 22, and 24. Base station a Enterer 30 has a dedicated forward traffic channel and reverse traffic char Sends and receives tunnels to and from the remote device 10. Dedicated traffic channel For example, the remote device 10 is another remote device special signature such as a power control command. Forward link, except that it can receive signaling information Similar to a broadcast channel. Mobile Exchange Center (MSC) 38 , Base Station Transceiver Subsystems 44, 48, and 50, including Base Station Tra Is it a set of system transceivers and a base station transceiver subsystem? Coordinate their signaling. Base station antennas 30, 32, and 34, and Base station transceiver subsystems 44, 48 and 50, as well as MSC38 The system provided is called base station 28. Communication manager 40 is that you Sys to a remote device where the user pressed the "Push-to-Talk" (PTT) button Manage the Internet, such as granting caller privileges. Preferred embodiment odor Air interface signaling and modulation is commonly referred to simply as IS-95. "Dual Mode Wideband Spread Spectrum Cellular System Mobile Station-Base Station Compatibility Standard (Mobile Station-Base Station Compatibility Standard for Dual-Mode Wideband Spread Spectrum Cellular S ystems) Code division multiple access described in TIA / EIA / IS-95 Compliant with CDMA systems. In IS-95, the remote device is a mobile station be called. The base station transceiver subsystem is sectorized into, for example, three sectors. It is technically well known that there is. Base station or base station transceiver subsystem When the term mu is used here, the term is a base station transceiver subsidy. To refer to the entire stem or a single sector of the base station transceiver subsystem It is implied that there is. In FIG. 1, the active remote device 10 is the base station transceiver subsystem. Has an established bidirectional link with the system 44. To be active The remote device 10 is an access channel message requesting a traffic channel. Send the page to the base station transceiver subsystem 44. The access message is Sent on the access channel. The access channel communicates with the base station Therefore, it is a reverse link channel used by remote devices. Access Cha A channel is a shared slotted random access channel. frequency Base station transceiver per channel Transceiver One remote device per sector You can safely use the access channel at one time. Access Cha Tunnels are short signaling messages such as calling, responding to pages and registering. Used for exchange. An access attempt is a series of access probes (access prob) It is sent by a remote device in e). Each access probes has the same information It carries information, but is transmitted at a higher power level than in the past. access The probe continues until a base station acknowledgment is received by the remote device. When the remote device 10 establishes a communication link, the dedicated forward link traffic Receives signaling that exists on the forward broadcast channel on the channel Believe. In this way, the remote device 10 is a forward link broadcaster. Does not monitor the tunnel, but it has its own dedicated forward link traffic channel Receives all of the dispatch system information on the system. The remote device 10 is dedicated It communicates back to the base station transceiver subsystem 44 on the reverse channel. Remote equipment Since the device 10 has its own dedicated forward link signal path, it is a remote device special message. Sage communication may be included in signaling. For example, the remote device 10 is If it can act as both a patch system remote device and a two-point telephone device , Remote device 10 is a two-point incoming call on the forward link traffic channel. May be informed that is aimed at the remote device 10. On the other hand, in FIG. 1, the passive remote devices 20, 22 and 24 are the base stations. Do not have an established reverse link signal for any of the Lanceva subsystems I. Remote devices 20, 22, and 24 are passive but still accessible Use channels to communicate with base stations. In a preferred embodiment, the passi Remote devices 20, 22 and 24 use access channels and base station trucks. Whether they are forward link broadcast channels to the system subsystem A signal tells you if you need more power. Base station Tran The sheba subsystem responds to power request access messages with forward linking. May increase the transmit power level of the loadcast channel. In standard CDMA systems, allowing remote devices to be active The number of processes that allocate resources, not just a significant amount of processing resources It can take seconds. Save system resources and avoid corresponding delays Therefore, in a preferred embodiment, the remote device is a push-to-talk button. Press to assign a set of resources. Remote device push-to-to When you release the button, the resource remains dedicated to the remote device for a period of time. The remote device is activated while the user is not pressing the push-to-talk button. It is designated as a tib and is said to be hanging. Hang The remote device sends and receives a series of low-speed idle messages to control link power. save. In this way, remote device users will subsequently push-to-talk At the push of a button, the link is fully established and responds immediately. This kind of behavior Handles the use of the dispatch system's natural dialog. Push-to-two Resources are released when the pause between talk launches exceeds the threshold. There is. After the resources are released, the remote device will occur on the access channel. You have to send a message and reestablish the connection. At any point in time , It is true that only one remote device can talk, but multiple remote devices are active It can be tib. The behavior of the system described above is very different from the standard push-to-talk behavior. May be different. A typical push-to-talk system has one thing in common It is realized by using the same frequency or a set of two frequencies. Remote device user Once you press the push-to-talk button, it will send at a common frequency and everything else Block access to the channel. Also, the user is another user Press your push-to-talk button even when the first talk Block the channel by. Normally, while the caller is talking, that person's receiver is defeated. Issable and avoids feedback. In this way, the remote device you The person presses the push-to-talk button and his receiver is disabled Then the user will not hear his own voice. Therefore, one If the push-to-talk button on your device stops and doesn't move, another user Not only is the system inaccessible, but the user himself also receives an invalid message. You may not be able to hear the warning message when it is sent. In a standard push-to-talk system, system caller privileges and corresponding There is no authorization for system caller privileges. In addition, the remote device is a push-to-talk button. There is no way to deny system caller privileges after pressing. Also a typical Sith It is difficult to detect speech activity in the system. The present invention is very different. In a preferred embodiment, a CDMA multiple access technique is used. (Alternative fruit Other multi-dimensional access techniques may be used in the examples). CDMA system In the stem, multiple remote devices can transmit at the same frequency at the same time. Remote device Even if it continuously sends, other remote devices in the area will access as well as others. Channels, dedicated traffic channels, and forward link broadcasters Until the same frequency can be used to communicate on the strike channel Up to. Also, the remote device sends and reverses the link traffic channel signal. While creating the forward link traffic channel signal Also note that you will continue to receive. Remote device user's voice is forward link trough If it is not included in the ic channel signal, the speaker on the remote device will say that the remote device is a system. Remains enabled while designated as a system caller. this In this way, the privileged device is pressed by the person's push-to-talk button. You will be able to compose voice messages on remote devices while you are. When the user first presses the push-to-talk button, the PTT_on display appears. It is sent from the remote device to the base station. User releases push-to-talk button Then, the PTT_off display is sent from the remote device to the base station. Usually PTT_off table Other users will be granted push-to-talk access until the indication is received There is nothing. One aspect of the invention is to prevent the PTT_off indication from being transmitted. Address situations where the push-to-talk button malfunctions. In a preferred embodiment, the remote device comprises a multirate vocoder. Eh. Multi-speed vocoders have minimal voice or data activity Send at low speed, and at high speed when level voice activity or data activity is high Believe. In a preferred embodiment, the built-in vocoder is 20 milliseconds (ms). Based on voice activity during the ram, for example about 8,000 bits per second (bps), 4 Four different things: 000bps, 2,000bps, and 1,000bps Create encoded data from a digital sample of audio information at the same speed. Bo Each frame of coder data is 9,600bps, 4,800bps, 2,40 Former with overhead bits like 0bps and 1,200bps Will be The fastest data frame equivalent to 9,600 bps frames Called a "full rate" frame. The 4,800bps data frame is "c" It is called a "freight" frame. The 2,400 bps data frame is "1 / Called a "4 rate" frame. And a 1,200 bps data frame Called a "1/8 rate" frame. A vocoder suitable for use in this environment "Variable Speed Boko" issued on May 9, 1995 and assigned to the assignee of the present invention. US Pat. No. 5,4 entitled "VARIALE RATE VOCODER" Explained in Nos. 14,796. The remote device is an external source such as a terminal device unit The remote device is also in variable speed frame format when receiving data from Continue processing data. The present invention, in the presence of minimal link data, We may take advantage of the fact that vocoders send 1/8 rate frames. There are two different scenarios addressed by the present invention. In the first scenario The user presses the push-to-talk button. Remote device is PTT_on table Send an indication and receive a channel assignment. However, intentionally or unexpectedly, The user does not speak. In addition, the PTT_off indication is not received at the base station. base The station will turn off PTT_ if the user does not release the push-to-talk button You may not receive the display. The base station also if the button stops and does not move Receives PTT_off indication if the remote device is otherwise malfunctioning You may not believe it. In a similar but slightly different second scenario, the user pushes Press the two-talk button. The remote device sends a PTT_on display and assigns a channel To receive. The user speaks and sends voice traffic to other net members .. However, intentionally or unexpectedly, the user speaks for an extended period of time. Stop. Again, the PTT_off indication is not received at the base station. The base station is Yu Receive PTT_off display if the user does not release the push-to-talk button May not. The base station can be remote-controlled if the button stops and does not move. If the device is malfunctioning in other cases, the PTT_off display will not be received. there is a possibility. In both scenarios, one of the net members has a higher priority Unless designated as a user and the wrong remote device can be "suspended", the system will be defeated. It will be locked. In such cases, other remote devices on the net become "callers". It cannot, and therefore disables the network. The present invention Such deadlocks by monitoring link (voice or data) activity Prevent The invention was filed on June 24, 1996 and is assigned to this assignee. "Methods for system protection of access control and dispatch systems And equipment (METHOD AND APPRATUS FOR ACCESS REGULATION AND SYSTEM PROTECTION OF A DISPATCH SYSTEM) , US patent application consecutive 08/6 No. 71,132, and filed June 24, 1996, assigned to this consignee "How to access the system efficiently in a dispatch system And equipment (METHODD AND APPRATUSS FOR EFFIC) IENT SYSTEM ACCESS IN A DISPATCH SYS Explained in U.S. Patent Application Consecutive No. 08 / 671,131 entitled "TEM)" Other mechanisms for blocking deadlocks and regulating system access, such as May be used with. There are multiple ways to detect link activity. Similar to the vocoder described above The average number of slow frames received over a period of time when a vocoder is used Is required. This method can also be applied to data transmission. in this way And sometimes background noise causes even faster frames , The lack of a valid continuous audio signal is still detected. Other low speed digital boco The data depends on whether the voice signal is voice or non-voice noise. Coding methods may be used. The base station encodes the signal and inspects the link activity You can monitor the display of the type of encoding used to output. Another idea Monitors the content of the spectrum of the encoded signal and determines the presence or absence of audio locate. Absence of data on the data connection can be even easier to detect There is also the possibility. For example, a base station may transmit an incoming signal or the number of incoming signals as compared to the total number of bits. Sometimes we just look at the average number of bits for which the value "1" is specified. FIG. 2 is a flowchart illustrating the basic operation of the present invention. preferable In an embodiment, the system is run by base station 28 (Figure 1). Sith The system is always resident in the MSC38 (Fig. 1), but some of its operations are in the base station. It can occur within the Lanceva subsystem. In the most common example The system may be located at any part of the communication system. In Figure 2 The system shown is real once for each remote device for which system caller privileges are granted. Will be done. From the start block 100, the operation is that the system caller privilege is authorized by the remote device. Block 102, which starts when received for. Such authorizations are usually remote. Responds to the PTT_on display received from the device. The two counts are still Lock 102 sets the initial value. The first data is transferred from the Ekaku device to the base station The base station is then sufficient to indicate that it is receiving active voice or data communications. Block 106 to determine if there is any linking activity. If not, T One count is incremented to reflect the passage of time, block 108. Block 11 0 asks if a denial of system caller privileges has been received. Remote equipment If the device releases the push-to-talk button, or the remote device moves to another remote device Therefore, such a denial may be received if interrupted. Denial received If so, the flow ends at block 114. If no denial is received The flow continues to block 112. T1 count is threshold, block 1 If threshold 1 is not crossed at 12, the flow returns to block 106 and continues. To. When the T1 count exceeds the threshold, the threshold 1 in block 112, the base The station creates an alternative PTT_off display and sends it to the communications manager, block 1 34 Thereby freeing the system for use by other remote devices. When link activity is detected in block 106, the flow that deals with the second scenario -Enter the second stage of the chart. If data continues to be transferred from the remote device to the base station , Block 116 monitors for link activity. Active voice or day If there is not enough link activity to indicate the reception of the communication, the T2 count will be incremented. , Reflects the passage of time within block 118. Block 120 is a system call Ask if a denial of personal privileges has been received. If a denial is received, the flow will be Exit with lock 128. If no denial is received, the flow blocks 12 Continue to 2. T2 count exceeds threshold, block 122 exceeds threshold 2 If not, the flow returns to block 116 and continues. T2 count is the threshold , In block 112, when the threshold 122 is exceeded, the base station replaces PTT_o. Create a display and send it to the communication manager, block 134 thereby other distant Release the system for use by the isolation device and the flow ends at block 138 To. If link activity is detected in block 116, the T2 count will be reset. Block 126. Block 130 receives a denial of system caller privileges Ask if it was. If a denial is received, the flow ends at block 136 To do. If no denial is received, the flow continues to block 116. The mechanisms deployed in blocks 106 and 116 for detecting link activity are the same. May be the same or different. One example of a link detection mechanism is received over a period of time It is to count the average number of slow frames. In this way, back Effective continuous sound when ground noise occasionally causes higher speed frames Lack of voice signal is still detected. In a preferred embodiment, a vocoder The frame is transferred in the air at a rate of 1 per 20 msec. block The 106 and 116 mechanisms may monitor 16 consecutive frames. Fure If 15 of the 16 in the game contains 1/8 rate data, the link activity is active. Not enough to show ugly use. When the base station sends an alternative PTT_off indication to the communications manager, the communications are managed. Can distinguish the alternative display from the PTT_off display received directly from the remote device. Sometimes it can't be done. The communication manager is an alternative PTT_o Upon receiving the display, the system caller privilege denial is sent to the remote device. May respond. Communication manager replaces PTT_off display and remote device If the PTT_off display created by is indistinguishable, the communication manager will May send denial in response to any PTT_off indication it receives .. If the send manager can distinguish between the two, an alternative PTT_off is received You only need to send a denial when it is done. In a preferred embodiment, the denial is It is sent to the remote device over the reverse link traffic channel. Remote device is no In response to approval, it stops sending active audio signals and becomes inactive. Either hangs or hangs. Remote device to the user It may respond by warning or taking corrective action. Note what the flowchart shown in Figure 2 works to achieve .. Top that usually consists of blocks 106, 108, 110 and 112 The loop is related to the first scenario. The top loop is the active voice Monitors link activity until data communication is received. The upper loop ends And below, which generally consists of blocks 116, 118, 120 and 122 The part loop is related to the second scenario. The lower loop receives as the call progresses Continue to monitor signal link activity. Threshold 1 and threshold 2 have the same value Note that it does not need to be. If these values are selected as the same value, a loop Collapses into a single loop. In the most common situation, threshold 1 is A value smaller than the threshold value 2 is set. User first push-to-talk When pressing a button, it has something that user wants to communicate with It is assumed that this is because. The user should not start communicating messages immediately If not, it probably tries to deadlock the error or system This is because there was a deliberate attempt. Once the user starts talking Threshold 2 is longer because it is assumed that the user will pause during the conversation. Threshold 1 may be set to a value such as 5-10 seconds. Threshold 2 , 10-20 seconds may be set. In the most common implementation, the invention prevents system deadlock. Moni the absence of voice or data information in the push-to-talk system It is a method and equipment for the operation. Needless to say, the general shown in Figure 2. The principle could be applied to a large number of different embodiments. For example, the lowest speed The ram may not be a 1/8 rate frame in the alternative embodiment. The present invention , Microphone or other audio path component, audio signal from remote device It will prevent deadlock in case of remote device failure so that it will not be transmitted .. There are many modifications and practices that fall within the scope of the invention. Implementation is all of the present invention May contain all elements, but does not exactly follow the flowchart in Figure 2. example For example, when the base station receives the PTT_off display from the remote device at any time, the flow The fact that the entire charting process is terminated is evident in the figure above. clear In addition, the same effect can be achieved by using interruptions instead of regular queries. Let's go. Also, rearrange the blocks in the flow without affecting the operation of the system. May be good. Also, if the text here refers to a "remote" device, some of the devices Also note that may be a wired device. The above description of a preferred embodiment will be made or used by one of ordinary skill in the art. Provided to be able to. Various modifications to these examples Is easily apparent to those skilled in the art, and the general principles set out here are the books. It can be applied to other embodiments without using the power of the invention. Therefore, the present invention is here. Consistent with the principles and new features disclosed herein, not limited to the examples shown. Must be given the widest range to do.