Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W84/00—Network topologies
  • H04W84/02—Hierarchically pre-organised networks, e.g. paging networks, cellular networks, WLAN [Wireless Local Area Network] or WLL [Wireless Local Loop]
  • H04W84/04—Large scale networks; Deep hierarchical networks
  • H04W84/08—Trunked mobile radio systems
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04B—TRANSMISSION
  • H04B7/00—Radio transmission systems, i.e. using radiation field
  • H04B7/14—Relay systems
  • H04B7/15—Active relay systems
  • H04B7/155—Ground-based stations
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W4/00—Services specially adapted for wireless communication networks; Facilities therefor
  • H04W4/06—Selective distribution of broadcast services, e.g. multimedia broadcast multicast service [MBMS]; Services to user groups; One-way selective calling services
  • H04W4/10—Push-to-Talk [PTT] or Push-On-Call services
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W76/00—Connection management
  • H04W76/40—Connection management for selective distribution or broadcast
  • H04W76/45—Connection management for selective distribution or broadcast for Push-to-Talk [PTT] or Push-to-Talk over cellular [PoC] services

Definitions

• This invention relates to trunked communication systems, including but not limited to repeater control in a trunked communication systems.
• Trunked communication systems are known to comprise a plurality of communication units, a limited number of communication resources that are transceived via a predetermined number of repeaters, or base stations, and a communication resource allocator that allocates the limited number of communication resources among the plurality of communication units.
• the communication units may be portable radios and/or mobile radios.
• the communication resources may comprise a TDM (time-division multiplexed) bus, a carrier frequency, a pair of carrier frequencies, or any RF (radio frequency) transmission means.
• TDM time-division multiplexed
• carrier frequency carrier frequency
• RF radio frequency
• trunked two-way communication systems provide mobile and portable communication units with wireless services similar to many wired communication networks.
• a typical trunked communication system site where each different site has a different physical location, is composed of a number of full- duplex repeaters, each coupled to a variety of devices to support interconnection to the public telephone network, mobile-to-mobile calling, and to one or more dispatcher console positions. These devices typically provide a centralized control for the repeaters. For example, a single central controller provides radio channel signalling encode and decode functions, authorization functions, resource determination functions, and communication activity logging.
• a single telephone interconnect switch typically provides the repeaters with an interface to one or more telephone lines to support telephone interconnect communication.
• a failure of the single device may render one or more of the desired services or functions inoperable, thus impairing communications in the system.
• Placing redundant devices within the system is expensive and an inefficient use of space and resources.
• FIG. 1 is a block diagram of an intelligent repeater in a trunked communication system in accordance with the invention.
• FIG. 2 is a diagram of an intelligent repeater in a trunked communication system with public network and private off-site network interfaces in accordance with the invention.
• FIG. 3 is a flowchart showing operation of a trunked communications system using a single intelligent repeater in accordance with the invention.
• FIG. 4 and FIG. 5 depict a flowchart showing operation of a trunked communications system using multiple intelligent repeaters in accordance with the invention.
• FIG. 6 is a flowchart showing testing of intelligent repeater functions in accordance with the invention.
• FIG. 7 is a flowchart showing distribution of system control functions amongst a plurality of intelligent repeaters in accordance with the invention.
• Each of a plurality of intelligent repeaters is equipped with an arrangement of components that uniquely distribute these service functions.
• the functions of radio channel signaling encode and decode functions, authorization functions, resource determination functions, and communication activity logging are distributed among the repeaters such that function placement adaptation insures continued service operation.
• An intelligent repeater 101 and a communication unit 102 interact with radio frequency (RF) signals 114 and 115, as illustrated in FIG. 1.
• the intelligent repeater includes a transmitter 105, a receiver 106, a signal processor 104, a central processing unit (CPU) 103, memory 108 for storage of information, and a switch 107.
• interfaces for interfacing control information and processed signals directly to an external communication network include, for example, a public interface 117, a private off-site interface 118, and a private on-site interface 119.
• RF signals 115 transmitted by the communication unit 102 are received by the receiver 106 of the intelligent repeater 101 through receive antenna 116. These transmissions may be modulated using a variety of techniques known in the art, such as, frequency modulation (FM), ampUtude modulation (AM), or a combination of the two. Further, the signals carried by the modulation may be frequency and or time division multiplexed. After reception, the signals are transferred to the signal processor 104, which may be a digital signal processor or DSP (e.g., a DSP56001 available from Motorola, Inc.), for further demodulation, decoding, and processing.
• DSP digital signal processor
• Control information is extracted from the signal and transferred to the CPU 103, which may be a microprocessor (e.g., an MC68302 microprocessor available from Motorola, Inc.).
• Other information present in the signal such as voice, images, and user data are transferred to the switch 107, which may be a cross-point matrix, time slot interchanger, or multiple-access packet link for routing.
• the switch provides a means to transfer control signals and information signals between the radio channel, the public network, the private off-site network, and the private on-site local area network (LAN).
• the other information may also be transferred, if necessary, to memory 108, which may be random access memory (RAM), for temporary storage.
• RAM random access memory
• the extracted control information may contain such things as the communication unit's individual and group identifications (IDs), and type of service requested.
• the CPU 103 uses this information in a manner described in FIG. 3, FIG. 4, and FIG. 5 to allocate resources and communicate with other system elements in order to appropriately serve the communication unit 102.
• the memory 108 is also used by the CPU 103 during the normal course of its processing to store and retrieve control information and program steps, as those represented in FIG. 3, FIG. 4, FIG. 5, FIG. 6, and FIG. 7, system database information, and any dynamic parameters needed during program execution.
• the switch 107 under control of the CPU 103, routes information from the signal processor 104 to one or more of the interfaces 109, 110, and 111.
• the content of the information and the configuration of the external network(s) determine to which interface(s) the information is routed.
• the public interface 109 if needed, is connected to one or more of many different public networks 117.
• the public interface 109 may be a standard telephone subscriber loop line, or it may be a standard data network line, such as one from an X.25 standard public packet data network.
• the private off-site interface 110 if needed, is typically connected to a private communications network 118 that is used to connect other sites of a multi-site radio network.
• the private off-site network 118 may be constructed of 4-wire analog lines, time division multiplex carriers, packet data links, and so forth.
• the private on-site interface 111 is connected to a LAN 119 that forms a communication link shared by other intelUgent repeaters of the system that are located at the same communication site, i.e., the same physical space where the intelUgent repeaters are located.
• the LAN 119 that the private on-site interface 111 is connected to may be a standard LAN, such as a LocalTalk LAN, an Ethernet
• LAN or FDDI (Fiber-Optic Distribution Data Interconnect) LAN.
• FDDI Fiber-Optic Distribution Data Interconnect
• the switch 107 is also used to route information that flows into the intelUgent repeater 101 from the interfaces 109, 110, and 111, to the signal processor 104. These signals are then processed by the signal processor 104 and transferred to the transmitter 105, where they are transmitted to the communication unit 102 through a transmit antenna 113.
• the RF signal 114 that is transmitted to the communication unit 102 may be modulated using any of the modulation techniques described above.
• a control bus 112 which may be a a multi-drop parallel data bus, serial data bus, or a time division multiplexed parallel or serial bus.
• each of the interfaces 109, 110, and 111 contains a microprocessor (e.g., an MC68302 microprocessor) that monitors the signal flow and determines whether the signals should be transferred to the CPU
• Intelligent repeaters 201 and 202 and their communication with one or more communication units 203 is illustrated in FIG. 2.
• in a trunked radio system there may be one or more intelUgent repeaters 201 and 202 located at one or more physical locations or sites.
• the number of intelUgent repeaters needed per location is based on the required capacity of the sum of the interfaces provided in terms of radio channel and external network interfaces.
• the locations of sites are chosen based on the desired RF coverage of a particular geographical area.
• Communication between intelligent repeaters 201 and 202 is necessary to enable the repeaters to operate in concert to provide consistent services.
• This communication is provided by assigning each component of the call estabUshment process to the communication unit(s) 203, because those units roam throughout the RF coverage area.
• a particular intelligent repeater at a site may be dedicated to transceiving control information to and from the communication unit(s) 203.
• This particular repeater is considered to provide the "control channel," a term well known in the art.
• Other intelUgent repeaters may be present at the site to be used for transceiving the typical voice, data, or image messages to and from the communication units 203.
• a communication unit 203 When a communication unit 203 makes a request for service on the control channel, that information is passed via the private on-site network 206 to the other intelUgent repeaters 201 and 202 at the site for request authentication and appropriate resource aUocation in accordance with the methods described below.
• a communication unit 203 when a communication unit 203 roams from the coverage area of one site into the coverage area of another, information is passed via the private off-site network 209 using communication links 207 and 208 such that appropriate resources may be placed into service at the new site, while the resources that were in service at the old site are deactivated.
• a communication unit 203 may request a telephone interconnect call. To connect this type of service to the communication unit 203, the intelUgent repeater that is transceiving the communication unit's RF signal 204 is typically connected directly into the public telephone network 212 via a standard telephone Une 211.
• the intelUgent repeater receives a request for service from a communication unit at step 301.
• the intelUgent repeater decodes the request at step 302 using the signal processor 104 and CPU 103 to determine what type of service is required by the communication unit.
• the request is authorized at step 303 by scanning a list stored in memory and comparing the ID of the communication unit sourcing the resource request to the stored Ust, which is a predetermined Ust of authorized IDs and the resources each ID may access, as different communication units may be authorized to use only certain communication resources. If the communication unit that sourced the request is not authorized for the requested communication resource, the request is rejected at step 305, which entails transmitting a rejection message to the requesting communication unit, and the processing ends for this call request.
• the appropriate resources needed to service the request are determined at step 306. If at step 307 the resource required is a pubUc resource, the pubUc interface is connected to the public resource via the switch 107 at step 308. If at step 309 the resource required is a private off-site resource, the private off-site interface is connected via the switch 107 at step 310.
• the radio transceiver, transmitter 105 and receiver 106, in the intelligent repeater, operably coupled to the signal processor 104, is also connected via the switch 107 at step 311, and processed signals are transferred between the communication unit and the requested resources, thus communications occur.
• the call is logged at step 314 by storing information such as the communication unit's individual and/or talkgroup IDs, the duration of the call, and the types of resources used.
• FIG. 4 and FIG. 5 A flowchart depicting operation of a trunked communications system using multiple intelUgent repeaters at a trunked communication site is shown in FIG. 4 and FIG. 5.
• An intelUgent repeater supporting control channel communications where resource requests are received from communications units and resource grants and transmitted in response, receives a resource request from a communication unit at step 401.
• the communication unit encodes the information in the resource request with an error control coding method to provide reliable operation in the RF environment.
• the intelUgent repeater supporting the control channel operations decodes 402 the information in the requesting transmission.
• the request information contains an ID of the requesting communication unit and also indicates what type of service is requested.
• the present invention enables the distribution of the component tasks of the call estabUshment process. Accordingly, the intelUgent repeater supporting the control channel operations decides which of the intelUgent repeaters will authorize access for the r- .T-T-iT-.ra-.-nT- resource request at step 403.
• Each intelUgent repeater has a Ust of which intelUgent repeater is assigned to carry out each component of the caU estabUshment process so that each step is directed to the appropriate intelUgent repeater.
• the appropriate intelUgent repeater is either the same repeater, the local choice, or another intelUgent repeater.
• the request information is transmitted via the private on-site interface over the site LAN to the intelUgent repeater that will carry out the authorization at step 404.
• the intelligent repeater assigned to carry out the authorization compares the identity of the requesting communication unit against a predetermined Ust of authorized communication unit IDs at step 405, as was previously described. If at step 406 the requesting communication unit's ID is not authorized for access, the request is rejected at step 407, which entails transmitting a rejection message to the requesting communication unit, and the processing ends for this call request.
• the intelUgent repeater supporting the control channel operations establishes at step 408 which of the intelUgent repeaters will determine required communication resources to fulfill the communication resource request.
• the appropriate intelUgent repeater is either the same repeater, the local choice, or another intelUgent repeater. If the resource determination function is carried out by another of the intelUgent repeaters, then the request information is transmitted via the private on-site interface over the site LAN to the intelUgent repeater that will carry out the resource determination at step 409.
• the intelUgent repeater assigned to carry out the resource determination analyzes what resources are required by looking at the type of service requested and matching it against a predetermined Ust of resources required for that service and checking if the resource(s) is available for that type of call, and the process continues with step 501 of FIG. 5.
• a radio channel resource is chosen to serve the requesting communication unit.
• the intelUgent repeater providing the radio channel resource may also be interconnected to the pubUc telephone network and/or to a private network to estabUsh the desired service.
• the interconnect may be routed through the private on-site interface to the LAN and to another on-site intelUgent repeater with an available public network or private off-site network resource. In this way, the distributed resources of the pluraUty of intelUgent repeaters at the trunked communication site are utiUzed to maintain communications at all times.
• the intelUgent repeater supporting resource allocation decides whether pubUc and private network resources are to be used, and if so, whether the resources are local or non-local.
• the public resource being assigned locally is considered. If at step 501 the pubUc network interface is not available within the same inteUigent repeater, then a connection is made at step 502 through the on-site LAN to an on-site intelUgent repeater with an available pubUc network resource (interface 109). If at step 501 the local pubUc network interface is available, it is connected within the same intelUgent repeater at step 503.
• the off-site private resource being assigned locally is considered. If at step 504 the off-site private network interface to an off-site private resource is not available within the same intelUgent repeater, then a connection is made through the on-site
• LAN to an on-site intelUgent repeater with an available off-site private network resource at step 505. If at step 504 the local off-site private network interface is available, it is connected within the same intelUgent repeater at step 506.
• the network interfaces chosen and assigned are connected at step 507 to the chosen radio resource, such as a frequency-pair channel to complete the requested call which transfers processed signals.
• Processed signals may be voice, data, and image information carried in any one of many formats by different physical media.
• the intelUgent repeater tests to see if the call is done at step 508.
• the communication unit transmits a call end signal that is detectable by the intelUgent repeater that provided the resources.
• the resources allocated to the call are disconnected by stopping the transfer of processed signals at step 509.
• a decision is made where to log the call activity. Logging typically involves storing key statistics related to the call into the memory of the intelUgent repeater. If the intelligent repeater that is assigned the logging function is not the intelligent repeater that provided the radio link, then the call information is passed to that logging intelUgent repeater over the on-site LAN at step 511.
• each intelUgent repeater may be capable of performing each component of the call establishment process, e.g., receiving a resource request over a radio channel, decoding the request, authorizing access, determining the required resources, connecting the resources, and logging the call summary.
• the components of the call estabUshment process may be distributed among the intelUgent repeaters that are capable of each component task.
• Such an arrangement is desired to provide non-stop system operation in the event that one of the intelligent repeaters suffers a partial or complete failure. It is therefore desirable to determine the capabiUties of these inteUigent repeaters by testing the status of their associated major components. Taking into account the results of such status testing, an assignment of the call components may be carried out such that the combination of the inteUigent repeaters work efficiently together to provide the desired communication services.
• FIG. 6 A flowchart depicting the status testing operation of each intelUgent repeater is shown in FIG. 6.
• the intelUgent repeater powers up at step 601. Alternatively and or additionally, this procedure could be activated on a demand basis in response to an status soU ⁇ tation request from a device external to the intelligent repeater.
• the core elements are tested at step 602.
• the core elements of an intelUgent repeater include the CPU 103, signal processor 104, memory 108, and switch 107. These core elements are critical to the operation of the intelUgent repeater and are tested and their status summarized together as each must be operational in order that the intelUgent repeater be assigned to any of the call estabUshment component tasks. Methods of testing each of these individual core elements are known in the art.
• the results of each test are checked to determine if all core elements passed at step 603. If all of the core elements pass their test, a status record in the memory is marked as pass at step 604. If one or more of the core elements fail its test, the status record is marked as fail at step 605.
• the status test of the radios e.g., transmitter 105 and receiver 106 associated with the intelUgent repeater is performed.
• Methods to individually test radio devices are known in the art.
• the radios or transceivers may operate at any frequency with any type of modulation and access method as supported by the CPU 103 and signal processor 104.
• the results of each test are checked to determine if all radios passed at step 607. If all of the radios passed, a status record in the memory is marked as pass at step
• a status test of the pubUc network interface associated with the inteUigent repeater is performed. Methods to individually test such interfaces are known in the art.
• the interface may be coupled to a pubUc network by way of any one of many physical line types, e.g., a standard telephone subscriber loop line or a standard data network line.
• the results of each test are checked to determine if the pubUc network interface passed. If all of the pubUc network interface tests pass, a status record in the memory is marked as pass at step 612. If one or more of the tests fail, the status record is marked as fail at step 613.
• a status test of the private off-site network interface associated with the inteUigent repeater is performed. Methods to individually test such interfaces are known in the art.
• the interface may be coupled to a private off-site network by way of one of many physical line types, e.g., 4-wire analog Unes, time division multiplex carriers, or packet data links.
• the results of each test are checked to determine if the public network interface passed. If all of the private off-site network interface tests pass, a status record in the memory is marked as pass at step 616. If one or more of the tests fail, the status record is marked as fail at step 617.
• a status test of the private on-site network interface associated with the intelUgent repeater is performed.
• Methods to individually test such interfaces are known in the art.
• the interface may be coupled to a private on-site network by way of one of many physical line types, e.g., a standard LAN, such as a LocalTalk LAN, an Ethernet LAN, or FDDI LAN.
• the results of each test are checked to determine if the private on-site network interface passed 619. If all of the private on-site network interface tests pass, a status record in the memory is marked as pas ⁇ at step 620. If one or more of the tests fail, the status record is marked as fail at step 621.
• the test results, or status information is transmitted at step 622 to the site resource manager, and the process continues with step 602 in order to keep the status information current.
• the site resource manager is a predetermined designation maintained by one of the intelUgent repeaters at each communication site.
• FIG. 7 A flowchart depicting the resource manager operation of an inteUigent repeater is shown in FIG. 7.
• the resource management function is a process that runs in a CPU 103 of one of the intelUgent repeaters at a trunked communication system site.
• the resource manager powers up.
• the resource manager receives status information reports from each of the intelUgent repeaters at step 702. In the preferred embodiment, the transmission of status information is carried over the private on-site LAN.
• the resource manager analyzes the status of the first inteUigent repeater at step 703.
• the status of the core element tests are checked to determine if aU core elements passed at step 704. If there was no pass at step 705, and the resource manager has not looked at all of the intelUgent repeaters' status reports at step 705, the resource manager checks the next inteUigent repeater in the Ust at step 706. If aU of the inteUigent repeater status records have indicated failure of the core elements at steps 704 and 705, the site is non-operational and a failure condition is declared at step 707. Such a situation is highly unUkely and results in an alarm being triggered to notify the appropriate personnel.
• an inteUigent repeater is found, at step 704, to have passed aU of its core element tests, that inteUigent repeater is selected at step 708 to perform the authorization of access functions and resource allocation functions associated with estabUshing communication services.
• the resource manager analyzes the status of the next inteUigent repeater at step 709.
• the status of the core element tests are checked to determine if aU core elements passed at step 710. If there was no pas ⁇ at step 710, and the resource manager has not looked at all of the intelUgent repeaters' status reports at step 711, the resource manager checks the next inteUigent repeater in the
• step 712 When an intelUgent repeater is found, at step 710, to have passed aU of its core element tests, that inteUigent repeater is selected at step 713 to perform logging functions associated with the estabUshing communication services. If aU of the intelligent repeater status records have indicated failure of the core elements at steps 710 and 711, the intelUgent repeater that was chosen to carry out authorization and resource allocation is also selected to carry out the logging function at step 713. At step 714, the resource manager informs the inteUigent repeaters of the assignment of authorize, allocation, and logging functions to the particular repeaters.
• Each intelUgent repeater is thus able to route caU establishment information to the proper inteUigent repeater assigned to carry out each function of the call process.
• the resource manager also informs the resource aUocation inteUigent repeater of the status information associated with each of the intelUgent repeaters at step 714.
• the resource allocator is thus able to aUocate communication resources from the available pool of site resources, such as radio channels, public network interfaces, or private off-site network interfaces.
• New status information is received from each of the inteUigent repeaters by the resource manager at step 715.
• Critical failure indications are checked at step 716. If a critical failure occurs, such as a core element failure in an intelUgent repeater assigned to the authorization, aUocation, or logging functions, the analysis and selection process repeats from step 703. If at step 716 there is no critical failure, the process continues with step 714.
• the resource manager may assign all functions to one inteUigent repeater, each function to a different repeater, or any combination in between. Because each repeater is capable of each control function, the resource manager is able to distribute the needed system functions throughout the system as needed, thus providing a highly flexible and reUable communication system.
• the flowchart of FIG. 7 does not reflect aU of these many possibiUties, for the sake of simpUcity and brevity of the drawings.
• the resource manager may also assign other control functions not Usted here.

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• Engineering & Computer Science (AREA)
• Computer Networks & Wireless Communication (AREA)
• Signal Processing (AREA)
• Mobile Radio Communication Systems (AREA)
• Radio Relay Systems (AREA)
• Facsimiles In General (AREA)
• Exchange Systems With Centralized Control (AREA)
• Interface Circuits In Exchanges (AREA)

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• 1992
  • 1992-06-29 US US07/905,925 patent/US5459761A/en not_active Expired - Lifetime
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• 1993
  • 1993-06-07 GB GB9403150A patent/GB2273633B/en not_active Expired - Fee Related
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  • 1993-06-07 BR BR9305561A patent/BR9305561A/pt not_active Application Discontinuation
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