MXPA98010548A - Method and apparatus for accelerated response to a petition for allocation of resources in a cdma receiving push-cdma receiving system using a cdma interconnection subsystem to range flame - Google Patents

Abstract

In a "push to talk" dispatch system, a method and apparatus for providing an accelerated response to a message originating from the "push to talk" system are discussed. A first base station (110A) allocates a first group of equipment (112A) to support a "push to talk" type connection. A first system controller (118) assigns a second group of equipment (12A, 126) to support a "push to talk" type connection. Upon receipt of a message originating from the "push to talk" system, coming from a first remote station (100), the first base station (110A) transmits the intermediate response to the first remote unit (199), instructing it to communicate to through the first team group (112A) and the second assigned team group (120A, 12

Description

METHOD AND APPARATUS FOR ACCELERATED REPLACEMENT TO A PETITION FOR ALLOCATION OF RESOURCES IN THE SYSTEM OF PRESS TO SPEAK OF CDMA USING A SUBSYSTEM OF INTERCONNECTION OF CDMA TO ROUTE CALLS.

BACKGROUND OF THE INVENTION I. Field of the Invention This invention relates in general to the allocation of resources in a dispatch system and, more particularly, to a rapid response to a resource allocation request from a remote unit.

II. BACKGROUND OF THE INVENTION In a wireless telephone communication system, many users communicate over the wireless channel to connect to other wired and wireless telephone systems. Communication over the wireless channel can be any of a variety of multiple access techniques. These multiple access techniques include time division multiple access (TDMA), frequency division multiple access (FDMA), and code division multiple access (CDMA). The CDMA technique has many advantages. An exemplary CDMA system is described in the Patents of the States P179S / 98MX United States No. 4,901,307 issued February 13, 1990 to K. Gilhousen et al., Entitled "SPREAD SPECTRUM MULTIPLE ACCESS COMMUNICATION SYSTEM USING SATELLITE OR TERRESTRIAL REPEATERS", assigned to the assignee of the present invention and incorporated herein as reference. In the aforementioned patent, a multiple access technique is presented, where a large number of users of the mobile telephone system, of which each has a transceiver, communicate through satellite repeaters, aerial repeaters or land base stations using broad spectrum communication signals from CDMA. By using CDMA communications, the frequency spectrum can be reused multiple times allowing for an increase in the capacity of "system users." In the CDMA cellular system, each base station provides coverage of a limited geographic area and links the remote units within. of its coverage area through a cellular system switch with the public switched telephone network (PSTN) When a remote unit moves to the coverage area of a new base station, the call routing of the remote unit is transferred to the new base station The path of transmission of the signal from the base station to the remote unit is referred to as the uplink and P1795 / 98MX The transmission path of the signal from the remote unit to the base station is referred to as the downlink. In an exemplary CDMA system, each base station transmits a pilot signal having a common pseudo-random noise (N N) dispersion or propagation code that is shifted in the code phase of the pilot signal from other base stations. During the operation of the system, the remote unit is provided with a list of the shifts of the code phase corresponding to the neighboring base stations surrounding the base station through which the communication was established. The remote unit is equipped with a search element with which it tracks the signal strength of the pilot signal from a group of base stations that include the neighboring base stations. A method and system for providing communication with a remote unit through more than one base station during the transfer process set forth in U.S. Patent No. 5,267,261 entitled "MOBILE ASSISTED SOFT HANDOFF IN A CDMA CELLULAR COMMUNICATIONS" are presented. SYSTEM ", granted on November 30, 1993 and assigned to the assignee of the present invention. Using this system, communication between the remote unit and the end user is not interrupted by P1795 / 98MX the eventual transfer from the original base station to a subsequent base station. This type of transfer can be considered as a "soft" transfer, since communication with the subsequent base station is established before communication with the original base station is terminated. When the remote unit is in communication with two base stations, the remote unit combines the signals received from each base station in the same way as multipath signals from a common base station are combined. In a typical macrocell system, a system controller can be used to create a single signal for the end user from the signals received by each base station. Within each base station, the signals received from a common remote unit can be combined before they are decoded and, thus, take full advantage of the multiple received signals. The decoded result of each base station is supplied to the system controller. Once a signal has been decoded, it can not be "combined" with other signals. In this way, the system controller must select among the plurality of decoded signals produced by each base station with which communication was established by P1795 / 98MX part of a single remote unit. The most advantageous decoded signal is selected from the set of signals of the base stations and the unselected signals are simply discarded. The soft handoff of the remote unit operates based on the strength of the pilot signal from several sets of base stations, as measured by the remote unit. The Active Set is a set of base stations through which active communication is established. The Candidate Set is a set of base stations selected from the Neighbor Set or the Remaining Set, which have a pilot signal strength at a signal level sufficient to establish communication. The Neighbor Set is a set of base stations that surround an active base station, comprising base stations that have a high probability of having a signal strength of sufficient level to establish communication. The Remaining Set comprises all the base stations of the system that are not members of the active, candidate or neighbor sets. When the communication is initially established, a remote unit communicates through a first base station and the Active Set contains only the first base station. The remote unit monitors the P1795 / 98 X intensity of the pilot signal of the base stations of the Active Set, of the Candidate Set, of the Neighbor Set and of the Remaining Set. When a pilot signal from a base station in the Neighbor Set or in the Remaining Set exceeds a level up ± > By default, the base station is added to the Candidate Set. The remote unit communicates a message to the first base station that identifies the new base station. A system controller decides whether to establish communication between the new base station and the remote unit. If the system controller decides to do so, the system controller sends a message to the new base station with the identification information about the remote unit and a command to establish communications with it. A message is also transmitted to the remote unit through the first base station. The message identifies a new Active Set that includes the first base station and the new base station. The remote unit searches for the new base station that transmitted the information signal and establishes communication with the new base station without terminating the communication through the first base station. This process can continue with additional base stations. When the remote unit is communicating through multiple base stations, it continues to monitor P1795 / 98MX the signal strength of the base stations of the Active Set, of the Candidate Set, of the Neighbor Set and of the Remaining Set. If the intensity of the signal corresponding to a base station of the Active Set falls below a predetermined threshold for a predetermined period of time, the remote unit generates and transmits a message to report this event. The system controller receives this message through at least one of the base stations with which the remote unit is communicating. The system controller may decide to terminate communications through the base station that has a weak pilot signal strength. The system controller, when deciding to terminate communications through a base station, generates a message identifying a new Active Set of base stations. The new Active Set does not contain the base station through which the communication ended. The base stations through which communication is established, send a message to the remote unit. The system controller also communicates information to the base station to terminate communications with the remote unit. In this way, communications from the remote unit are routed only through the base stations identified in the new P1795 / 98MX Active Set. Because the remote unit is communicating with the end user through at least one base station all the time through the smooth transfer process, there is no interruption in communication between the remote unit and the end user. A smooth transfer provides significant benefits in its inherent "set before cutting" technique over and above the conventional "cut before set" technique used in other cellular communication systems. In a wireless telephone system, maximizing the capacity of the system in terms of the number of simultaneous telephone calls that can be handled is extremely important. The capacity of the system in a wide-spectrum system can be maximized if the transmission power of each remote unit is controlled in such a way that each transmitted signal reaches the receiver of the base station at the same level. In a real system, each remote unit can transmit the minimum signal level that produces a signal-to-noise ratio that allows for acceptable data recovery. If a signal transmitted by a remote unit reaches the receiver of the base station at a power level that is very low, the bit error rate can be very high to allow communications from P1795 / 98MX high quality, due to the interference coming from the other remote units. On the other hand, if the signal transmitted from the remote unit is at a power level which is very high when it is received at the base station, communication with this particular remote unit is acceptable but this high power signal acts as an interference to the other remote units. This interference can adversely affect communications with other remote units. Therefore, to maximize the capacity in an exemplary CDMA broad spectrum system, the transmit power of each remote unit within the coverage area of a base station is controlled by the base station to produce the same signal strength received nominal at the base station. In the ideal case, the total power of the signal received at the base station is equal to the nominal power received from each remote unit multiplied by the number of remote units that transmit within the coverage area of the base station plus the power received at the base station. the base station from the remote units in the coverage area of the neighboring base stations. The path loss in the radio channel can be characterized by two separate phenomena: path loss and average fading. He P1795 / 98MX uplink, from the base station to the remote unit, operates at a different frequency than the downlink, from the remote unit to the base station. However, because the uplink and downlink frequencies are within the same general band of frequencies, there is a significant correlation between the average path loss of the two links. On the other hand, fading is an independent phenomenon for the uplink and the downlink and varies as a function of time. In an exemplary CDMA system, each remote unit estimates the path loss of the uplink, based on the total power at the input to the remote unit. The total power is the sum of the power of all the base stations operating in the same frequency assignment as perceived by the remote unit. From the estimate of the average uplink path loss, the remote unit sets the transmission level of the downlink signal. If the downlink channel of a remote unit improves suddenly compared to the uplink channel for the same remote unit, due to the independent fading of the two channels, the signal as received at the base station from this remote unit would increase its power. This increase P1795 / 98MX in the power causes additional interference to all signals that share the same frequency assignment. In this way, a rapid response from the remote unit transmitting the power to the sudden improvement in the channel would improve the performance of the system. Therefore, it is necessary to make the base station continuously contribute to the power control mechanism of the remote unit. The transmission power of the remote unit can also be controlled by one or more base stations. Each base station with which the remote unit is in communication, measures the intensity of the signal received from the remote unit. The intensity of the measured signal is compared to a desired signal strength level for that particular remote unit. A power adjustment command is generated by each base station and sent to the remote unit in the uplink. In response to the power adjustment command of the base station, the remote unit increases or decreases the transmission power of the remote unit by a predetermined amount. Through this method, a rapid response to a change in the channel is made and the average performance of the system is improved. Note that in a typical cellular system, the base stations are not intimately connected and each base station in the system is not P1795 / 98MX prevented or aware of the power level at which the other base stations receive the signal from the remote unit. When a remote unit is in communication with more than one base station, the power adjustment commands are supplied from each base station. The remote unit acts on these power base adjustment commands of the multiple base stations to avoid transmitting power levels that can adversely interfere with other communications of remote units and still provide sufficient power to support the communication of the remote unit with at least one of the base stations. This power control mechanism is achieved by causing the unit to raise the level of the transmission signal only if each base station with which the remote unit is in communication requests an increase in the power level. The remote unit decreases its transmission signal level if any base station with which the remote unit is in communication requests that the power be decreased or reduced. A system for the base station and power control of the remote unit is disclosed in U.S. Patent No. 5,056,109 entitled "METHOD AND APPARATUS FOR CONTROLLING TRANSMISSION PCWER IN A CDMA CELLULAR MOBILE TSLEPHONE SYSTEM", granted on October 8. of 1991, assigned to the Assignee of the present invention.

P1795 / 98 X It is also desirable to control the relative power used in each data signal transmitted by the base station in response to the control information transmitted by each remote unit. The primary reason for providing this control is to admit the fact that in certain places, the uplink channel may, in an unusual way, have disadvantages. Unless the power that will be transmitted to the remote unit at a disadvantage is increased, the quality of the signal may become unacceptable. An example of this location or place is a point where the path loss to one or two neighboring base stations is almost the same as the path loss with the base station communicating with the remote unit. In this place or location, the total interference would increase by three over the interference observed by a remote unit at a point relatively close to its base station. In addition, the interference from the neighboring base stations does not fade in unison with the signal from the active base station as would be the case for the interference from the active base station. A remote unit in this situation may require 3 to 4 dB of additional signal strength from the active base station to obtain or achieve adequate performance. At other times, the remote unit may be P1795 / 98 X located where the ratio of signal to interference is unusually good. In this case, the base station could transmit the desired signal using a transmission power lower than normal, reducing interference with other signals that are transmitted by the system. To achieve the above objectives, the ability to measure the signal to interference within the receiver of the remote unit can be provided. This measurement is made by comparing the power of the desired signal with the total interference and the power of the noise. If the measured proportion is less than a predetermined value, the remote transmits a request to the additional power base station in the uplink signal. If the ratio exceeds the predetermined value, the remote unit transmits a request for power reduction. One method by which the receiver of the remote unit can monitor the signal to interference ratios is by monitoring the frame error rate v (FER) of the resulting signal. Another way is by measuring the number of erasures received. The base station receives the power adjustment requests from each remote unit and responds by adjusting the power allocated to the corresponding uplink signal by a predetermined amount. The adjustment P1795 / 98MX is normally small, such as it may be, on the order of 0.5 to 1.0 dB, or about 12%. The rate or rate of power change may be a bit slower than that used for the downlink, perhaps once per second. In the preferred embodiment, the dynamic range of the adjustment is normally limited, such as, for example, 4 dB less than the nominal one to about 6 dB greater than the nominal transmission power. The base station must also consider the power demands that will be made by other remote units when deciding if the requests of a particular remote unit are met. For example, if the base station is charged to capacity, additional power requests can be granted but only 6% or less, instead of 12% normal. In this regime, a request for a reduction in power would also be granted at the normal 12% change. When the original cellular telephony licenses were granted by the government, one of the restrictions for the use of the spectrum was that the operators would not provide dispatch system services. However, due to the great advantages of the CDMA system and the inherent expense and problems of deployment and maintenance of private shipping systems, the government is re-examining this P1795 / 98 X question. The government itself would benefit greatly from these services. While the typical wired and wireless telephone service provides point-to-point service, the forwarding services provide one-to-many service. The common use of the expedition services are the local police radio systems, taxi dispatch systems, operations of the Federal Bureau of Investigation (FBI) and the secret service, and military communication systems in general. The basic model of an expedition system consists of a network of user dissemination. Each user of the broadcast network monitors a common broadcast uplink signal. If a user of the network wants to speak, press a "push to talk" (PTT) button. Normally, the voice of the talking user is routed from the downlink through the broadcast uplink. Ideally, the dispatch system allows landline and wireless access to the system. When a user of a remote unit that is part of a dispatch system presses the "push to talk" button or simply "talk button", he would like to start talking immediately. However, in conventional wireless systems, an amount of time is necessary P1795 / 98MX noticeable to establish a link before the user can start talking. The present invention is a solution for reducing to an acceptable level the amount of perceptible time that is necessary to establish a link.

SUMMARY OF THE INVENTION The present invention is a method and an apparatus for providing an accelerated response to a message originated by the conversation button, in a dispatch system. A set of resources in a base station and in a controller are pre-assigned to create a communication connection from the base station to the equipment that creates the uplink broadcast signal. When a remote unit presses the conversation button, the base station responds immediately with a radiolocation message corresponding to the preassigned path.

BRIEF DESCRIPTION OF THE DRAWINGS The features, objects and advantages of the present invention will be more evident from the detailed description set forth below when considered together with the drawings, wherein: Figure 1 shows a typical system of P1795 / 98MX shipment; and Figure 2 shows a more detailed representation of a typical dispatch system.

DESCRIPTION OF THE PREFERRED MODALITIES Figure 1 shows a typical dispatch system. In the preferred embodiment, the remote units 10, 20, 22 and 24, can operate both as dispatch units and point-to-point telephones. In Figure 1, the remote unit 10 is currently a calling unit or an originating unit of the active call and the remote units 20, 22 and 24 are at this time passive listeners. The base stations 30, 32 and 34 can provide the broadcast uplink channel to the remote units 20, 22 and 24. The base station 30 connects a dedicated or exclusive upstream and downstream channel to the remote unit 10. The channel Dedicated or exclusive traffic is similar to the uplink broadcast channel with the exception of, for example, that the remote unit 10 can receive specific signaling information from another remote unit such as power control commands. The dedicated or exclusive traffic channel also carries power control and signaling information. The base station 30 is also receiving a downlink signal P1795 / 98MX from the remote unit 10 active. In the preferred embodiment, the power control in the dedicated traffic channel link of the renota unit 10 is achieved as described above. The mobile switching center (MSC) 38 coordinates the signaling to and from the base stations. The communication handler 40 controls the network in such a way that the generalization of the requests if two of the remote units press the "push to talk" or "talk" (PTT) button at the same time. In the preferred embodiment, signaling and modulation of the air interface is in accordance with the code division multiple access (CDMA) system described in "Mobile Station-Base Station Compatibility Standard for Dual-Mode ideband Spread Spectrum Cellular Systems" TIA / EIA / IS-95, generally referred to simply as IS-95. In IS-95, the remote unit is referred to as a mobile station. It is well known in the art that base stations can be sectorized, such as, for example, in three sectors. In the present, where the term base station is used, it is implied that the term may refer to a complete base station or to a single sector of a multi-sector or multisector base station. In Figure 1, the active remote unit 10 has P1795 / 98MX a bidirectional link established with the base station 30. To activate, the remote unit 10 sends an access channel message requesting a traffic channel to the base station 30. The access message is sent on the access channel. The access channel is a downlink channel used by the remote units to communicate with the base station. The access channel is used for exchange of short signaling messages, such as call origins, responses to radiolocations and registration. An access attempt is sent by the remote unit in a series of access probes. Each access probe carries the same information but is transmitted at a higher power level than the previous one. The access probe continues until an acknowledgment or acknowledgment from the base station is received in the remote unit. The access channel is a slotted and shared random access channel. Only a remote unit can successfully use the access channel at a time. Also, because each successive access probe is sent at an increasing power level compared to the previous one and that the access channel is not controlled power, the access channel acts as interference for the other link signals falling. For these reasons, it is advantageous to keep the number of P1795 / 98 X access attempts at a minimum. When the remote unit 10 has established a communication link, it receives signaling from the upstream broadcast channel in a dedicated or exclusive downlink traffic channel. In this way, the remote unit 10 does not monitor the uplink broadcast channel and receives all the dispatch system information on its own dedicated uplink traffic channel. The remote unit 10 communicates back to the base station 30 in a dedicated down channel. In the preferred embodiment, the power control in the uplink and downlink is performed as described above in accordance with IS-95. Because the remote unit 10 has its own dedicated uplink signal path, the specific message of the remote unit can be included in the signaling. For example, if the remote unit 10 has the ability to operate or operate both as a remote unit of a dispatch system and as a point-to-point telephone unit, the remote unit 10 can be informed on the uplink traffic channel. that an incoming point-to-point call is being directed to the remote unit 10. On the other hand, in Figure 1, the massive remote units 20, 22 and 24 do not have a link signal Descending P1795 / 98MX established with none of the base stations. Note that if the remote units 20, 22 and 24 are completely passive, the individual base stations may not be aware of whether the remote units are in their corresponding coverage areas. Even if a remote unit registers with the base station when it enters the coverage area of a base station, the base station has no way of knowing at what point the remote unit has left the coverage area of the base station. Even if the remote units 20, 22 and 24 are passive, they can still use the access channel to communicate with the base stations. In the preferred embodiment, the passive remote units 20, 22 and 24 use the access channel to signal to the base station whether they need more power from the uplink broadcast channel. Within the power request access message, various level or signal quality indications may be included. For example, there may be a field indicating the intensity at which the remote unit perceives the pilot signal from the base station. A standard cellular system is comprised of a plurality of base stations, each of which provides communication for remote units located within a limited coverage area. Together with P1795 / 98MX plurality of base stations, provides coverage to an entire service area. When an expedition system is leased by a leasing entity, the leasing party may wish to provide coverage over the entire service area. However, if the uplink broadcast signal is transmitted from each base station in the system at all times, the cost of the system can be very high. A more efficient and economical way that provides superior global capacity. for the system it is to transmit the uplink broadcast channel only from those base stations in which a remote unit is located and transmit the uplink broadcast channel to the minimum level required to provide reliable communication. If the uplink broadcast channel has not been transmitted, the corresponding resources are available to other point-to-point or broadcast users. In addition, the other users in the coverage area of the base stations that are not transmitting the uplink broadcast channel are not subject to interference from them. Remember that the pilot signal is continuously transmitted from each base station without considering whether the uplink broadcast channel is being transmitted. The present invention is a method of procreating P1795 / 98 X a path before the press to speak button is pressed. The preassigned path can comprise all the resources needed for an air interface connection through the switch and back to the resource that is creating the uplink broadcast channel. The pre-assigned path can comprise only a subset of all the necessary resources. For example, normally the connection to and from the switch can be assigned very fast. Therefore, the portion of the link to and from the switch may not need to be pre-allocated in order to have a sufficiently low response time. In the preferred embodiment explained below, the terminology used is associated with the specific apparatus and method for implementing the base station and the mobile switching center. However, the present invention relates in general to the pre-allocation of resources and can be applied to a variety of different architectures and operating systems. When a remote unit initiates a point-to-point connection, a series of transactions must occur to allocate resources. For example, Figure 2 shows a more detailed representation of a typical dispatch system. In Figure 2, the CDMA interconnect subsystem 116, the control processor 124 The P1795 / 98MX call and the system controller 118 may be included within the MSC 38 of Figure 1. The remote unit 100 has the ability to operate or operate both as a dispatch unit and as a point-to-point unit. To initiate a point-to-point connection, remote unit 100 sends a source message on an access channel that designates the identity of the remote unit, the type of service requested and the party to which the call should be connected. The base station 110A receives the message and sends a message to the system controller 118 through the CDMA interconnection subsystem 116. The system controller 118 sends a message back to the base station 110A, which in response sends a message on the radiolocation channel to the remote unit 100 recognizing the reception of the access message. The system controller 118 should notify the call control processor (CCP) 124, which monitors the call. The call control processor 124 handles any variety of services that may be requested (e.g., point-to-point services, push to talk services, data services or secure voice services). The call control processor 124 allocates system resources among the various entities or requesting parties. To manage the call, both hardware and software resources are assigned. For example, P1795 / 98MX the modulator / demodulator pair 112 is signed to the base station 110A. The CDMA interconnection system (CIS) 116 connects the modulator / demodulator pair 112 to the system controller 118. Within the system controller 118, the selector 120A is assigned to handle the call. From selector 120A, switch 126 is used to connect the call to the PSTN or to connect the call back to the system controller 118. The address designations of the allocated resources and the control information must be passed between the various entities or parts to establish a path from the remote unit 100 to the PSTN. As said, more than 30 messages should be sent to establish a traffic channel from point to point. The communication of the messages and the allocation of the resources can require from one to three seconds. For a normal point-to-point call, even a delay of three seconds is tolerable and will probably go unnoticed by the end user. Normally, when a user places a point-to-point call, they must wait while the destination phone rings. Three additional seconds do not greatly affect the amount of time you should wait for the answer. In a prior art expediting system, when a remote unit initially oppresses the P1795 / 98MX push button to talk, a series of analogous transactions must occur to allocate the resources to support the connection. By contrasting the operation of a point-to-point system with the operation of a push-to-speak dispatch system, in an issuing system, when the user of the remote unit presses the push button to speak, he would like to start talking immediately. A delay of three seconds is not acceptable to the user. A typical dispatch system specifies a maximum delay time of 300 or 400 milliseconds. But note another difference between an expedition system and a point-to-point system. With a point-to-point connection, there is no a priori knowledge of the destination of the requested connection before the call source message is received from the remote unit. In the dispatch system, the destination of the requested connection is known before the conversation button is pressed. Also in an issuing system, each passive remote unit can register and, therefore, when a remote unit presses the talk button, it is already authorized and its profile has been approved by the call control processor 124. For example, in a dispatch system of Figure 2, assume that the remote unit 98 is a member of the network and is located in the coverage area of the antenna P1795 / 98MX 106B of base station 110B. Assume also that the remote unit 96 is a member of the network and is located within the coverage area of the 106X antenna of the 110X base station. Assume further that the remote unit 100 is a member of the network and is located within the coverage area of the antenna 106A of the base station 110A. Therefore, it is known that the uplink broadcast channel will be transmitted from each of the base stations 110A, 110B and 110X. Assume further, for example, that a connection of the switch 126 has been established via the selector 120A, through the CIS 116 through the modulator / demodulator 112A on the antenna 106A to transmit the uplink broadcast channel in the area of coverage of the base station 110A. Because the signal transmitted by the modular / demodulator 112A is the common updraft signal, only the modulator portion of the chip / demodulator pair 112A is in use. In the case of broadcasting, the corresponding broadcast return link channel is not established. Therefore, the demodulator portion of the modulator / demodulator pair 112A is left unoccupied as well as the downlink processing components of the selector 120A. Note that if more than one remote unit is monitoring the link broadcast signal P1795 / 98MX ascending common in the coverage area of the base station 110A, each remote unit monitors the same uplink broadcast signal and additional resources will not be required to support the multiple remote units. For each of the remote units 96 and 98 there may be a similar path. Alternatively, because the uplink broadcast signal is the same for all passive remote units, a single selector can control a plurality of different modulator / demodulator pairs in different base stations. For example, the selector 120B can control a modulator / demodulator in the base station 110B and a modulator / demodulator in the base station 110X. The CIS 116 connects the signal coming from the selector 120B with the base stations 110B and 110X. If the remote unit 100 presses the conversation button, a connection of the remote unit 100 with the switch 126 must be established. Then, the signal of the remote unit 100 is routed from the switch 126 back to the selector or selectors that are creating the signal uplink broadcasting Note that this path is determinable even before the remote unit 100 presses the talk button. In the most general mode, a pre-assigned P1795 / 98MX dedicated or exclusive path. For example, in the base station 110A, the modulator / demodulator 112B is assigned and connected by the CIS 116 to the selector 120C. As indicated above, a connection of the selector 120C with the switch 126 can also be established. An additional connection of the switch 126 can be preassigned back to the selector (s) (ie, the selector 120A and the selector 120B) that are creating the uplink diffusion. These pre-allocated resources are left unoccupied or free until a remote unit in the coverage area of the base station 110A sends an access message that designates that the talk button has been pressed. Instead of starting the series of three-second transactions required to allocate a set of resources, the base station 110A immediately sends a response to the remote unit in the paging channel that designates the traffic channel corresponding to the pre-allocated resources. Immediately, the preassigned uplink resources begin to send the modified uplink broadcast channel in the corresponding uplink traffic channel. The signal transmitted to an active remote unit in a dedicated traffic channel is modified from the diffusier channel, uplink in several aspects. By P1795 / 98MX example, an originating unit of the active call may not want to hear its own voice coming from the air-connection. Also the dedicated upstream traffic channel sends the downlink power control information to the remote unit, as well as other signaling information. As indicated above, the system operates at the highest capacity when the power level of each remote unit is precisely controlled by the base station. Normally, the remote units that are monitoring the uplink broadcast channel are not transmitting and, therefore, do not need the downlink power control information. The uplink signal transmitted in the dedicated traffic channel is power controlled by the active remote unit, such that it is at the minimum level required for the proper operation of the active remote unit. When a remote unit presses the conversation button, a set of resources is assigned, as described above. When the remote unit releases the talk button, the resources remain dedicated to the remote unit for some period of time. During the time when the user is not pressing the talk button, the remote unit sends a series of null messages at low speed to preserve the control of P1795 / 98MX link power. In this way, when the user of the remote unit subsequently presses the conversation button, the link is fully established and responds immediately. This type of operation supports the natural use of an expedition system. The natural use of an expedition system is for a remote unit to initiate a dialogue. After a remote unit initiates a connection, it sends a series of push messages to talk. When the pause between activating press to speak exceeds a threshold, resources can be released. After the resources have been released, the remote unit must send a source message on an access channel to re-establish the connection. If there is more than one remote unit within the coverage area of the base station 110A while the remote unit 100 is active, a new set of pre-allocated resources may be established. Although it is true that at any time only one remote unit may be talking, more than one remote unit may be active. If the immediate response of the system to a source access message will be retained, a new set of resources must be assigned to support a subsequent active remote unit in the same base station. The allocation of an independent and unique resource set for each sector of each station P1795 / 98MX base that is transmitting the uplink broadcast channel, consumes a considerable amount of resources. In an alternative modality, instead of providing an independent and unique set of resources, a variety of overlapping trajectories are established. For example, each of the base stations 110A, 110B and 110X can each pre-assign a modulator / demodulator pair. However, a single selector can be assigned in the system controller 118 as the pre-assigned resource for each of the three connections. Only one of the base stations 110A, 110B and 110X can actually allocate the resource to an active remote unit. When the first of the base stations 110A, 110B and 110X allocates the preassigned resource to a remote unit connection, a new preassigned connection is established using a different selector. An improved and more elegant alternative mode makes use of the replacement demodulator associated with the modulator / demodulator pair that the uplink broadcast channel is providing. In the improved and more elegant alternative mode, the following actions occur. When the uplink broadcast channel is established, a corresponding downlink path is preassigned but unoccupied. When an indication of pressing is received to speak from P1795 / 98MX of a remote unit, the corresponding base station responds immediately by sending a radiolocation message. The radiolocation message designates that the remote unit must begin to transmit on the downlink traffic channel associated with the uplink broadcast channel. The remote unit uses approval to become an active unit and begin transmitting immediately on the designated downlink channel. The new active remote unit monitors the uplink broadcast channel. The base station begins to provide the power control information to the remote unit in the uplink broadcast channel. Any other remote unit that may be monitoring the uplink broadcast channel of this base station simply ignores the power control information, because they ordinarily do not have the downlink signal to which the control commands of the base station are applied. downlink power. Meanwhile, the base station requests the resources for the active remote unit through a process similar to the three-second process described above. When resources are available, the base station sends a channel allocation message to the remote unit in the uplink broadcast channel. The remote unit performs P1795 / 98MX a channel pair switching and begins to use the new dedicated uplink and downlink traffic channel. The uplink broadcast channel no longer needs to include the downlink power control information. The downlink resources associated with the uplink broadcast channel resource are again unoccupied and available to address a subsequent push-to-talk source message. During the time in which the new active remote unit is transmitting in the downlink traffic channel associated with the uplink broadcast channel, any power control mechanism within the base station that autonomously decreases the power level of the downlink channel. Uplink broadcast channel in the particular sector in which the originating unit of the call is located may need to be temporarily disabled. For example, if the power control is achieved in a manner consistent with the power control mechanism described in copending patent application No. 08 / 660,618 entitled "METHOD AND APPARATUS OF POWER CONTROL IN A CDMA DISPATCH SYSTEM" presented on 6 June 1996 and assigned to the assignee of the present invention, then the base station monitors an access channel for the power increase commands. Yes one P1795 / 98 X passive remote unit requires more power from the uplink broadcast channel, transmits a power request access message to the base station in the access channel. The base station responds to the power request access message by increasing the power level of the uplink broadcast channel in the sector. If access: power request messages are not received, the base station slowly decreases the power to which the uplink broadcast channel transmits. The recently active remote unit communicates in the traffic channel and is unable to simultaneously transmit an access message. In order to ensure that the remote unit continues to receive an adequate power level, the base station can pause for the slow decrease in power during the time that the new active remote unit is transmitting on the downlink traffic channel associated with the uplink broadcast channel. Of course, the power control process must still respond with an increase in the power level if a power request access message is received from another remote unit within the same coverage area. The previous description of the preferred embodiments is provided to allow any P1795 / 98 X person skilled in the art makes or uses the present invention. The various modifications to these modalities will be readily apparent to those skilled in the art and the generic principles defined herein can be applied to other modalities without using the inventive faculty. Thus, it is not intended that the present invention be limited to the embodiments shown herein but be in accordance with the broadest scope consistent with the novel principles and features disclosed herein.

P1795 / 98MX

Claims (16)

1. NOVELTY OF THE INVENTION Having described the present invention, it is considered as a novelty and, therefore, the content of the following claims is claimed as property: 1. A method for providing an accelerated response to a source message of type oppress for speak, in an expedition system, the dispatch system has a plurality of remote units, a plurality of base stations and a mobile system controller, the method comprises the passes of: preassigning a first set of equipment to support the oppressive connection to speak in each of the plurality of base stations; preassign a second set of equipment to support the oppress connection to speak to the mobile system controller; receiving at a first base station an origin message of oppress to speak, coming from a first remote unit; and transmitting from the first base station directly, in response to the push-to-talk source message, a radiolocation to the first remote unit that directs the first remote unit to establish communication through the equipment sets First and second P1795 / 98MX, wherein the step of pre-assigning the second set of equipment comprises the step of pre-assigning at least one mobile system controller selector to route calls between a switch and a CDMA interconnect subsystem. The method according to claim 1, wherein the step of assigning the first set of equipment comprises the step of pre-selecting a modulator / demodulator in each of the plurality of base stations corresponding to an upward broadcast link and a forward link. Descending traffic that will be used to communicate with the first remote unit. The method according to claim 1, further comprising the step of pre-selecting a communication path from one of the control selectors of the preselected mobile system to the switch and from the switch, with at least one of the selectors of the mobile system controller . The method according to claim 1, further comprising the step of providing a power control signal to the first remote unit. 5. An apparatus for providing an accelerated response to a source message of oppression to speak in a dispatch system, the dispatch system has P1795 / 98MX a plurality of remote units, a plurality of base stations and a mobile system controller, the apparatus comprises: a first pre-assigned set of equipment for communicating with a first remote unit; a second pre-assigned set of equipment to support the push-to-talk connection in the mobile system controller; a first base station for receiving the source message of oppressing to speak and, directly in response, transmitting a radiolocation to the first remote unit, indicative of the pre-assigned modulator / demodulator through which it communicates; a CDMA interconnection subsystem for routing calls between the plurality of base stations and the mobile system controller; and a central call processor, located in the mobile system controller, for pre-assigning the modulator / demodulator located in each of the plurality of base stations, wherein the second pre-assigned equipment set is at least one pre-assigned selector for routing calls between a switch and the CDMA interconnection subsystem. 6. The apparatus according to claim 5, in P1795 / 98MX where the first pre-assigned equipment set is a modulator / demodulator located at each of the base stations to provide an uplink broadcast link and a downlink traffic link to the first remote unit. The apparatus according to claim 5, further comprising a pre-assigned switch for routing communications between a pre-assigned first selector and at least one other pre-assigned selector. 8. A method to provide an accelerated response to an origin message of oppress to speak in an expedition system, the dispatch system has a plurality of remote units, a plurality of base stations and a mobile system controller, the method comprises the steps of: pre-assigning a first modulator / demodulator in each of the plurality of base stations to provide a link of upstream broadcasting to the plurality of remote units and to provide a downlink traffic to a first remote unit; preassign a first set of equipment to support the accelerated response in the mobile system controller; receive in a first base station the origin message of oppress to speak, coming from the first P1795 / 98MX remote unit; transmit from the first base station directly in response to the originating message of oppressing to speak, a radiolocation message to the first remote unit directing the first remote unit to establish a communication link through the first pre-assigned modulator / demodulator and the first set of equipment; assigning a second modulator / demodulator in the first base station and a second set of equipment in the mobile system controller; and transferring the communication link to the second modulator / demodulator and the second set of equipment and terminating the communication link with the first pre-assigned modulator / demodulator and the first set of equipment, wherein the step of pre-assigning the set of equipment comprises the step of pre-assigning at least one mobile system controller selector to route calls between a switch and a CDMA interconnection subsystem. The method according to claim 8, further comprising the step of preselecting a communications path from one of the control selectors of the preselected mobile system to a switch and from the switch to at least one of the selectors. P1795 / 98MX mobile system drivers. The method according to claim 8, wherein the step of transmitting further comprises the steps of: sending power control information to the first remote unit using the pre-assigned modulator / demodulator; and ignoring the power control information by all remote units, with the exception of the first remote unit. The method according to claim 10, further comprising the step of sending power control information to the first remote unit, using the second modulator / demodulator after the communication link has been transferred to the second modulator / demodulator and the second set of equipment. The method according to claim 8, wherein the step of transferring further comprises: sending a channel assignment message to the first remote unit, indicative of a second modulator / demodulator through which it communicates; switching the communication link of the pre-assigned modulator / demodulator and the first set of equipment to the second modulator / demodulator and to the second set of equipment; and discontinue the control information of P1795 / 98MX power through the pre-assigned modulator / demodulator. 13. An apparatus for providing an accelerated response to an originating message of oppression to speak in a dispatch system, the dispatch system has a plurality of remote units, a plurality of base stations and a mobile system controller, the apparatus comprises: a pre-assigned modulator / demodulator in each of the plurality of base stations to provide an uplink broadcast link to the plurality of remote units and to provide a downstream traffic link to be used by a first remote unit; a pre-assigned set of 'equipment in the mobile system controller to support the accelerated response to the source message of pressing to speak; a second modulator / demodulator, located in each of the plurality of base stations, to accept a communication in progress between the first remote unit and the pre-assigned modulator / demodulator; a second set of equipment in the mobile system controller to accept the communication of the first equipment set-a first base station in communication with the first remote unit to request the second P1795 / 98MX modulator / demodulator and the second set of equipment with the reception of the origin message to press to speak; a central processor of Hadasdas to pre-assign the pre-assigned modulator / demodulator and to assign a second modulator / demodulator with the request of the first base station; and means for switching the communications of the first modulator / demodulator and the pre-assigned equipment set to the second modulator / demodulator and the second set of equipment. wherein the preassigned set of equipment comprises at least one selector located in the mobile system controller for routing calls between the switch and a CDMA interconnection subsystem. 14. The apparatus according to claim 13, which further comprises a communication path from one of the selectors to the switch and from the switch to at least one of the selectors. The apparatus according to claim 13, wherein the second set of equipment comprises at least one selector located in the mobile system controller for routing calls between a switch and a CDMA interconnection subsystem. 16. The apparatus according to claim 15, further comprising a communication path from one of P1795 / 98MX the selectors to the switch and from the switch to at least one of the selectors. P179S / 98MX