WO1997020401A1 - Systeme perfectionne de service radio relie a un satellite - Google Patents

Systeme perfectionne de service radio relie a un satellite Download PDF

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Publication number
WO1997020401A1
WO1997020401A1 PCT/US1996/019165 US9619165W WO9720401A1 WO 1997020401 A1 WO1997020401 A1 WO 1997020401A1 US 9619165 W US9619165 W US 9619165W WO 9720401 A1 WO9720401 A1 WO 9720401A1
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WO
WIPO (PCT)
Prior art keywords
met
net
group
central controller
satellite
Prior art date
Application number
PCT/US1996/019165
Other languages
English (en)
Inventor
C. Edward Sigler
Richard S. Sweet
Original Assignee
Amsc Subsidiary Corporation
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from US08/657,479 external-priority patent/US5717830A/en
Application filed by Amsc Subsidiary Corporation filed Critical Amsc Subsidiary Corporation
Priority to CA002238646A priority Critical patent/CA2238646C/fr
Priority to AU12763/97A priority patent/AU1276397A/en
Publication of WO1997020401A1 publication Critical patent/WO1997020401A1/fr
Priority to US09/114,289 priority patent/US6477370B1/en

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Classifications

    • 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
    • H04B7/185—Space-based or airborne stations; Stations for satellite systems
    • H04B7/1853—Satellite systems for providing telephony service to a mobile station, i.e. mobile satellite service
    • H04B7/18567—Arrangements for providing additional services to the basic mobile satellite telephony service
    • 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
    • H04B7/185—Space-based or airborne stations; Stations for satellite systems
    • H04B7/18578—Satellite systems for providing broadband data service to individual earth stations

Definitions

  • the present invention relates generally to a satellite trunked radio service system for satellite communication, and more particularly, to a satellite trunked radio service system for satellite communication utilizing a shared satellite demand period circuit associated with private voice networks .
  • NCS Network Control System
  • the satellites each transmit and receive signals to and from METs at L-band frequencies and to and from Network Communications Controllers (NCCs) and
  • Feederlink Earth Stations at Ku-band frequencies. Communications at L-band frequencies is via a number of satellite beams which together cover the service area.
  • the satellite beams are sufficiently strong to permit voice and data communications using inexpensive mobile terminals and will provide for frequency reuse of the L-band spectrum through inter- beam isolation.
  • a single beam generally covers the service area .
  • the satellite network system provides the capability for mobile earth terminals to access one or more multiple beam satellites located m geostationary orbit for the purposes of providing mobile communications services.
  • the satellite network system is desired to provide the following general categories of service:
  • MTS Mobile Telephone Service
  • PSTN public switched telephone network
  • MRS Mobile Radio Service
  • PN private network
  • MTCRS Mobile Telephone Cellular Roaming Service
  • MTCRS Mobile Data Service
  • DTE data terminal equipment
  • DCE data communications equipment
  • the satellites are designed to transmit signals at L-band frequencies in the frequency band 1530-1559 MHz. They will receive L-band frequencies in the frequency band 1631.5 - 1660.5 MHz. Polarization is right nand circular in both bands. The satellites will also transmit in the Ku frequency band, 10,750 MHz to 10,950 MHz, and receive Ku-band signals in the frequency band 13,000 to 13,250 MHz.
  • the satellite transponders are designed to translate communications signals accessing the satellite at Ku-band frequencies to an L-band frequency m a given beam and vice versa.
  • the translation will be such that there is a one-to-one relation between frequency spectrum at Ku-band and frequency spectrum in any beam at L-band.
  • the satellite transponders will be capable of supporting L-band communications in any portion of the 29 MHz allocation m any beam.
  • Transponder capacity is also provided for Ku-band uplink to Ku-band down-link for signalling and network management purposes between FESs and NCCs .
  • the aggregate effective isotropic radiated power (AEIRP) is defined as that satellite e.i.r.p. that would result if the total available communications power of the communications subsystem was applied to the beam that covers that part of the service area.
  • the satellite network system interfaces to a number of entities which are required to access it for various purposes.
  • Figure 3 is a context diagram of the satellite network system illustrating these entities and their respective interfaces.
  • Three major classes of entities are defined as user of communications services, external organizations requiring coordination, and network management system.
  • the users of satellite network communications services are MET users who access the satellite network system either via terrestrial networks (PSTN, PSDN, or Private Networks) or via METs for the purpose of using the services provided by the system.
  • FES Frequency Division Multiple Access
  • Owner/Operators are those organizations which own and control FESs that provide a terrestrial interface to the satellite network. When an FES becomes a part of the satellite network, it must meet specified technical performance criteria and interact with and accept real ⁇ time control from the NCCs. FES Owner/Operators determine the customized services that are offered and are ultimately responsible for the operation and maintenance of the FES. Customers and service providers interact with the Customer Management Information System within the Network Management System.
  • the satellite network system interfaces to, and performs transactions with, the external organizations described below:
  • Satellite Operations Center (SOC) : The SOC is not included m the satellite network ground segment design. However, the satellite network system interfaces with the SOC m order to maintain cognizance of the availability of satellite resources (e.g. m the event of satellite health problems, eclipse operations, etc.) and, from time to time, to arrange for any necessary satellite reconfiguration to meet changes m traffic requirements NOC The satellite network system interfaces with the satellites located therein via the NOC for a variety of operational reasons including message delivery and coordination.
  • satellite resources e.g. m the event of satellite health problems, eclipse operations, etc.
  • the satellite network system interfaces with outside organizations which lease resources on satellite network satellites and which are responsible for managing and allocating these resources m a manner suited to their own needs.
  • This external entity represents outside organizations which do not lease resources on satellite network satellites but with whom operational coordination is required.
  • the satellite network management system (NMS) is normally located at an administration's headquarters and may comprise three major functional entities;
  • CMIS Customer Management Information System
  • NE/SE Sy ⁇ tem Engineering
  • Customer Management Information System This entity provides customers and service providers with assistance and information including problem resolution, service changes, and billing/usage data.
  • Customers include individual MET owners and fleet managers of larger corporate customers .
  • Service providers are the retailers and maintenance organizations which interact face to face with individual and corporate customers .
  • Network Engineering This entity develops plans and performs analysis m support of the system. Network Engineering analyzes the requirements of the network. It reconciles expected traffic loads with the capability and availability of space and ground resources to produce frequency plans for the different beams within the system. In addition, Network Engineering defines contingency plans for failure situations.
  • the satellite network system comprises a number of system elements and their interconnecting communications links as illustrated m Figure 4.
  • the system elements are the NOC, the NCC, the FES, the MET, the Remote Monitor Station (RMS) , and the System Test
  • the interconnecting communications links are the satellite network Internetwork, terrestrial links, the MET signaling channels, the Interstation signaling channels, and the MET-FES communications channels.
  • the major functions of each of the system elements are as follows: NOC.
  • the NOC manages and controls the resources of the satellite network system and carries out the administrative functions associated with the management of the total satellite network system.
  • the NOC communicates with the various internal and external entities via a local area network (LAN) /wide area network (WAN) based satellite network Internetwork and dial-up lines.
  • LAN local area network
  • WAN wide area network
  • the NCC manages the real time allocation of circuits between METs and FESs for the purposes of supporting communications.
  • the available circuits are held m circuit pools managed by Group Controllers (GCs) within the NCC.
  • GCs Group Controllers
  • the NCC communicates with the NOC via the satellite network Internetwork, with FESs via Ku-to-Ku band interstation signaling channels or terrestrial links, and with mobile terminals via Ku-to- L band signaling channels.
  • the FES supports communications links between METs, the PSTN, private networks, and other MTs . Once a channel is established with an MET, call completion and service feature management is accomplished via In-Band signaling over the communication channel .
  • Two types of FESs have been defined for the satellite network system; Gateway FESs and Base FESs. Gateway FESs provide MTS, MRS, MTCRS and NR services. Base FESs are for like services and/or value added services.
  • the MET provides the mobile user access to the communications channels and services provided by che satellite network system.
  • a range of terminal types has been defined for the satellite network system.
  • the RMS monitors L-band RF spectrum and transmission performance in specific L-band beams.
  • An RMS is nominally located in each L-band beam.
  • Each RMS interfaces with the NOC via either a satellite or terrestrial link.
  • the STS provides an L-band network access capability to support FES commissioning tests and network service diagnostic tests.
  • the STS is collocated with, and interfaced to, the NOC.
  • Communications channels transport voice, data and facsimile transmissions between METs and FESs via the satellite. Connectivity for MET-to-MET calls is accomplished by double hopping the communications channels via equipped FESs. Signaling channels are used to set up and tear down communications circuits, to monitor and control FES and MET operation, and to transport other necessary information between network elements for the operation of satellite network
  • the system provides Out-of-Band and Interstation signaling channels for establishing calls and transferring information. In-Band signaling is provided on established communications channels for supervisory and feature activation purposes.
  • a detailed description of the satellite network signaling system architecture is provided in L. White, et al . , "North American Mobile Satellite System Signaling Architecture," AIAA 14th International Communications Satellite Conference, Washington, DC (March 1992) , incorporated herein by reference .
  • the satellite network Internetwork provides interconnection among the major satellite network ground system elements such as the NOCs, NCCs, and Data Hubs, as well as external entities.
  • Various leased and dial-up lines are used for specific applications within the satellite network system such as backup interstation links between the NCC and FESs and interconnection of RMSs with the NOC.
  • the primary function of che NOC is to manage and control the resources of the satellite network system
  • Figure 5 is a basic block diagram of the NOC and its interface.
  • the NOC computer is shown with network connections, peripheral disks, fault tolerant features, and expansion capabilities to accommodate future growth.
  • the NOC software is represented as two major layers, a functional layer and a support layer.
  • the functional layer represents the application specific portion of the NOC software.
  • the support layer represents software subsystems which provide a general class of services and are used by the subsystems in the functional layer.
  • the application specific functions performed by the NOC are organized according to five categories: fault management, accounting management, configuration management, performance management, and security management .
  • the general NCC Terminal Equipment (NCCTE) configuration showing constituent equipment includes: processing equipment, communications equipment, mass storage equipment, man-machine interface equipment, and optional secure MET Access Security Key (ASK) storage equipment.
  • the Processing Equipment consists of one or more digital processors that provide overall NCC control, NCS call processing, network access processing and internetwork communications processing.
  • the Communications Equipment consists of satellite signaling and communications channel units and FES terrestrial communication link interface units.
  • the Mass Storage Equipment provides NCC network configuration database storage, call record spool buffering an executable program storage.
  • the Machine Interface Equipment provides operacor command, display and hard copy facilities, and operator access to the computer operating systems.
  • the MET ASK storage Equipment provides a physically secure facility for protecting and distributing MET Access Security Keys.
  • the NCCTE comprises three functional subsystems: NCCTE Common Equipment Subsystem, Group Controller Subsystem, and Network Access Subsystem.
  • the NCCTE Common Equipment subsystem comprises an NCC Controller, NCCTE mass storage facilities, and the NCCTE man- machine interface.
  • the NCC Controller consists of processing and database resources which perform functions which are common to multiple Group Controllers. These functions include satellite network Internetwork communications, central control and monitoring of the NCCTE and NCCRE, storage of the network configuration, buffering of FES and Group Controller call accounting data, transfer of transaction information to the Off-line NCC and control and monitoring of FESs.
  • the Mass Storage element provides NCC network configuration database storage, call accounting data spool buffering, and NCCTE executable program storage
  • the Man-machine Interface provides Operator command and display facilities for control and monitoring of NCC operation and includes hard copy facilities for logging events and alarms.
  • a Group Controller (GC) is the physical NCC entity consisting of hardware and software processing resources that provides real time control according to the CG database received from the NOC
  • the Group Controller Subsystem may incorporate one to four Group Controllers.
  • Each Group Controller maintains state machines for every call m progress withm the Control Group It allocates and de- allocates circuits for FES-MET calls withm each beam of the system, manages virtual network call processing, MET authentication, and provides certain elements of call accounting When required, it provides satellite bandwidth resources to the NOC for AMS (R) S resource provisioning.
  • the Group Controller monitors the performance of call processing and satellite circuit pool utilization. It also performs MET management, commissioning and periodic performance verification testing.
  • the Network Access Subsystem consists of satellite interface channel equipment for Out-of-Band signaling and Interstation Signaling which are used to respond to MET and FES requests for communications services.
  • the Network Access Processor also includes MET communications interfaces that are used to perform MET commission testing.
  • the subsystem mcludes terrestrial data link equipment for selected FES Interstation Signaling.
  • FES The principal function of the FES is to provide the required circuit switched connections between the satellite radio channels, which provide communications links to the mobile earth terminals, and either the PSTN or PN.
  • FESs will be configured as Gateway Stations (GS ) to provide MTS and MTCRS services or Base Stations to provide MRS and Net Radio services (described m detail below) .
  • Gateway and Base functions can be combined m a smgle station.
  • the FES operates under the real time control of the Network Communications Controller (NCC) to implement the call set-up and take-down procedures of the communications channels to and from the METs.
  • NCC Network Communications Controller
  • Control of the FES by the NCC is provided via the interstation signaling channels.
  • An FES will support multiple Control Groups and Virtual Networks.
  • the FES is partitioned into two major functional blocks, the FES RF Equipment (FES-RE) and the FES Termmal
  • FES-TE The principal function of the FES- RE is to provide the radio transmission functions for the FES.
  • FES- RE In the transmit direction it combines all signals from the communications and interstation signaling channel unit outputs from the FES-TE, and amplifies them and up-convert these to Ku-Band for transmission to the satellite via the antenna.
  • signals received from the satellite In the receive direction, signals received from the satellite are down-converted from Ku-Band, amplified and distributed to the channel units within the FES-TE. Additional functions include satellite induced Doppler correction, satellite tracking and uplmk power control to combat rain fades.
  • the principal function of the FES-TE is to perform the basic call processing functions for the FES and to connect the METs to the appropriate PSTN or PN port.
  • the FES Under control of the NCC, the FES assigns communications channel units to handle calls initiated by MET or PSTN subscribers.
  • the FES-TE also performs alarm reporting, call detail record recording, and provision of operator interfaces.
  • an FES may m some cases be collocated with the NCC.
  • the NCC RF Equipment will be shared by the two system elements and the interstation signaling may be via a LAN. Connection to and from the PSTN is via standard
  • North American interconnect types as negotiated with the organization providmg PSTN interconnection. This will typically be a primary rate digital interconnect . Connection to and from private networks is via standard North American interconnect types as negotiated with the organization requesting satellite network service. This will typically be a primary rate digital interconnect for larger FESs or an analog interconnect for FESs equipped with only a limited number of channels may be employed.
  • CUG Closed User Group
  • Each member of the group can also talk when needed.
  • the system behaves like a radio multi-party line where several parties communicate over the same communication channel.
  • Public services and law enforcement agencies are typical users of this service, which is normally provided by either traditional terrestrial radio networks or by the more recent trunked radio systems.
  • These trunked systems generally m the 800-900 MHz band, provide groups of end users with virtual private systems by assigning frequencies to CUGs on a demand basis.
  • CCG User Group
  • MET user while communicating m a first closed user group, to have the capability to efficiently transmit a priority message to a predetermmed closed user group. It is another feature and advantage of the present invention to generally effectively and efficiently effectuate transmissions between mobile communication devices and the satellite network in a closed user group environment by utilizing an efficient communication protocol It is another feature and advantage of the invention to provide the capability for the Closed User Group arrangement to be used alternately with a private point-to-point voice communication between two parties It is another feature and advantage of the invention to provide a nationwide and regional pomt- to-multipomt mobile communication service that is not limited in coverage
  • the present invention is based, part, on the desirability of providing point to multipoint circuit switched connections between mobile termmal subscriber stations and a central base station Mobile users are able to listen to two-way conversations and to transmit usmg a push-to-talk mode of operation.
  • a mobile communication system mcludes a satellite communication switching office having a satellite antenna for receiving/transmitting a satellite message via a satellite from/to a vehicle using a mobile communication system, a satellite interface system, a central controller receiving/transmitting the satellite message from/to the satellite communication switching office issued from the vehicle via the satellite and the satellite interface system
  • the mobile communication system includes a user interface system providing a user interface through which a user has access to services supported by the mobile satellite system, and an antenna system providing an interface between the mobile communication system and the mobile satellite system via the satellite interface system, and receiving a first satellite message from the satellite and transmitting a second satellite message to the satellite
  • the antenna system includes an antenna including one of a directional and an omnidirectional configuration, a diplexer, an amplifier, a low noise amplifier, a beam steering unit when the antenna is of the directional configuration, and at least one of a compass and sensor to determme vehicle orientation.
  • the mobile communication system also includes a transceiver system, operatively connected to the antenna system, including a receiver and a transmitter
  • the transmitter converts the second satellite message mcludmg at least one of voice, data, fax and signaling signals mto a modulated signal, and transmits the modulated signal to the antenna system
  • the transmitter mcludes an amplifier, a first converter and associated first frequency synthesizer, a modulator, an encoder, multiplexer, scrambler and frame formatter for at least one of voice, fax, and data
  • the receiver accepts the first satellite message from the antenna system and converts the first satellite message mto at least one of voice, data, fax and signaling signals, at least one of the voice, data and fax signals routed to the usei interface system
  • the receiver includes a second converter with an associated second frequency synthesizer, a demodulator, a decoder, demultiplexer, descrambler and frame unformatter for at least one of voice, fax, and
  • the mobile communication system also mcludes a logic and signaling system, operatively connected to the transceiver, controlling initialization of the mobile communication system, obtaining an assigned outbound signaling channel from which updated system information and commands and messages are received.
  • the logic and signaling system configures the transceiver for reception and transmission of at least one of voice, data, fax and signaling messages, and controls protocols between the mobile communication system and the mobile satellite system, and validating a received signalling messages and generating codes for a signaling message to be transmitted.
  • a system for providing satellite communication between multiple users a closed user group arrangement mcludes first and second mobile earth terminals (METs) responsively connected to and registering with the mobile satellite system.
  • the first MET selects a closed user group network identifier (NET ID) representing a NET group mcludmg the first and second METs to establish voice communication therewith and transmits the NET ID to a central controller.
  • the central controller receives the NET ID from the first MET, validates the first MET for communication, validates the NET ID, allocates a frequency for the NET group, and broadcasts the message to the NET group including the second MET informing the
  • a method of providing satellite communication between multiple users a closed user group arrangement mcludes the steps of first and second mobile earth terminals (METs) registering with the mobile satellite system, the first
  • the method also mcludes the steps of the first MET transmitting the NET ID to the central controller, the central controller receiving the NET ID, validating the first MET for communication, validating the NET ID, allocating a frequency for the NET group, and broadcasting the message to the NET group mcludmg the second MET informing the NET group of the allocated frequency and the voice communication associated therewith.
  • the method also includes the steps of the second MET tuning to the frequency m response to the message broadcast by the central controller, and assigning by the central controller the first MET as current speaker for the NET group.
  • the method also mcludes the step of monitoring by the first and second METs whether at least one of a dispatcher message, a priority message and a release of speaker message has been issued, and if so, interrupting the current speaker with the at least one of the dispatcher message, the priority message and a new speaker.
  • the method also includes the steps of monitoring by the central controller whether the current speaker is active, and if not, removing the current speaker and setting the current speaker to vacant, notifying by the central controller the first and second METs that the current speaker is vacant, and initiating by one of the first and second METs a request to be the new speaker.
  • the method further includes the steps of receiving by the central controller the request from a first of the one of the first and second METs to be the new speaker, and assigning the first of the one of the first and second METs as the new speaker, and releasing the closed user group communication when no request from the one of the first and second METs is made to be the new speaker for a predetermined period of time.
  • the method also mcludes the steps of a third MET mcluded in the NET group registering with the mobile satellite system, and the central controller broadcasting the message to tne NET group mcludmg the third MET informing the NET group of the allocated frequency and the voice communication associated therewith
  • the method also mcludes the steps of the third MET tuning to the frequency m response to the message broadcast by the central controller by generating a scrambling vector for access thereto.
  • the third MET gams access to the frequency and the voice communication of the NET group using the scrambling vector.
  • the central controller advantageously controls the closed user group satellite communication mcludmg net radio parameters used by the first and second METs.
  • the central controller also selectively downloads the NET IDs to the first and second METs according to predetermmed user criteria
  • the central controller advantageously collects billing information regarding the closed user group satellite communication and transmits the billing information to the mobile satellite system.
  • the mobile satellite system optionally charges a service fee to a customer that has requested the closed user group arrangement instead of each of the individual users in the NET group thereby consolidating the billing transactions and permitting a single customer to monitor communication charges.
  • the method mcludes the steps of a non-MET accessing the mobile satellite system via either a public switched telephone network or a cellular network to initiate a closed user group communication with the NET group including at least one of the first and second METs, the central controller broadcasting the message to the NET group informing the NET group of the allocated frequency and the voice communication associated therewith, and the at least one of the first and second METs tuning to the frequency response to the message broadcast by the central controller to communicate with the non-MET the closed user group arrangement .
  • the method mcludes the steps of the first MET selecting the closed user group network identifier (NET ID) representing a NET group mcludmg the first MET and a non-MET serviced by one of a public switched telephone network and a cellular network to establish voice communication therewith, and the first MET transmitting the NET ID to the central controller.
  • NET ID closed user group network identifier
  • the method mcludes the central controller receiving the NET ID, determmmg that the NET group mcludes the non-MET, and broadcasting a non-MET message to either the public switched telephone network or the cellular network mcludmg the voice communication associated therewith, and either the public switched telephone network or the cellular network receiving the non-MET message from the central controller and transmitting the non-MET message to the non-MET to establish the closed user group arrangement between the MET and the non-MET.
  • the first MET beneficially mcludes a push to talk (PTT) device for generating the release of speaker message
  • PTT push to talk
  • the first MET activates the PTT device generating a PTT signal only when the PTT device is activated after the current speaker is vacant, relieving congestion on the satellite by selectively transmitting the PTT signal .
  • the central controller advantageously selectively downloads monitor codes to the first and second METs according to predetermined user criteria.
  • the monitor code functions to lock the first and second METs to the NET group preventing the NET group from being released when no request has been made by the first or second METs to be the current speaker after the predetermined period of time.
  • a priority default operation is provided.
  • the first MET and the central controller implement the following operations: (1) assigning, by the first MET, a default priority NET group for receiving a priority message when a priority button of the first MET is activated;
  • NAUCRSU NAU Control Unit
  • NRCHASU a predetermined number of times in a predetermmed number of consecutive superframes for a NET Radio channel assignment
  • a MET storing a first security key generates a scrambling vector for access to the voice communication.
  • the scrambling vector is generated m accordance with the followmg operations:
  • the system further provides dual standby operation permitting voice communication alternately between a closed user group arrangement (NET radio) and a mobile telephone service (MTS) .
  • NET radio closed user group arrangement
  • MTS mobile telephone service
  • At least one of the first and second METs implement the function of responding either to a MTS page request indicating the mobile telephone service s being requested or to a NET radio channel assignment request as transmitted on a GC-S channel
  • the first or second METs responds to a service request of either the closed user group arrangement or the mobile telephone service, the first or second MET is not required to monitor the GC-S channel for service requests for the other service.
  • Fig- 1 is a diagram illustrating an overview of the satellite network system
  • Fig. 2 is a diagram illustrating key performance parameters of the satellite used in the satellite network system
  • Fig. 3 is a diagram of the satellite network system illustrating components and respective inter aces
  • Fig. 4 is a diagram of a satellite network system illustrating a number of system elements and their interconnecting communications links;
  • Fig. 5 is a basic block diagram of the NOC and its interfaces,-
  • Fig. 6 is a basic block diagram of the physical architecture of the mobile earth terminal
  • Fig. 7 is a basic block diagram of the functions of the mobile earth terminal
  • Fig. 8 illustrates the basic concept and elements mvolved in establishment of communications and control m the Net Radio system
  • Fig. 9 is a diagram of an example of a Net Radio service subscribing organization with several communication nets;
  • Figs. 10A-10C are flowcharts of the overall process conducted by the various components in establishment of communications and control in the Net Radio system;
  • Fig. 11 illustrates the service categories for Net Radio
  • Fig- 12 illustrates the additional GC-S messages m each group
  • Fig 13 is an illustration of the format of the NID_SU
  • Fig. 14 is an illustration of the content of the NID-SU
  • Fig. 15 is an illustration of the format of the NA_SU
  • Fig. 16 is an illustration of the content of the NA_SU
  • Fig 17 is an illustration of the format of the NRCHA_SU
  • Fig. 18 is an illustration of the content of the NRCHA-SU
  • Fig. 19 is an illustration of the MET-ST messages that are of the Network Management Category
  • Fig. 20 is an illustration of the format oi the
  • Fig 21 is an illustration of the content of the MMA-SU
  • Fig 22 is an illustration of the format of the NRACR_SU
  • Fig 23 is an illustration of the content of the NRACR-SU
  • Fig. 24 is an illustration identifying the messages m each call control group
  • Fig. 25 is an illustration of the content of the
  • FIG. 26 is an illustration identifying MET timing requirements
  • Fig. 27 is an illustration identifying MET call monitor codes
  • Fig 28 is an illustration of a MET originated net radio call message flow
  • Fig 29 is an illustration of a MET originated Net Radio call setup event tree
  • Fig 30 is an illustration of a symbol key for use m the various figures including the event tree figures;
  • Fig. 31 is an illustration of a MET call monitoring event tree
  • Fig. 32 is an illustration of a MET call supervision event tree
  • Fig 33 is an illustration of a MET PTT frame structure
  • Figs. 34 (a) -(c) are illustrations of a Net Radio call release message flow and frame structure;
  • Fig. 35 is an illustration of a perceived hangtimer for MET users;
  • Fig. 36 is an illustration of a MET originated private mode call setup message flow
  • Fig. 37 s an illustration of a MET Priority 1 event tree
  • Fig. 38 is a diagram of the Net ID ASK security key generation process
  • Fig 39 is a diagram of the Authentication Security Key generation process
  • Fig 40 is a diagram of the Access Security Check
  • Fig 41A is a flow chart of the keying process
  • Fig 41B is an illustration of the keying process m the satellite communication system
  • Fig. 41C is a signal/data diagram of the keying process
  • Fig. 42 is a diagram of a bulletin board in the satellite communication system
  • Fig. 43 is a diagram of the scrambling vector generation process for the NET Radio service
  • Figs. 44A and 44B are diagrams of the authentication process using the authentication security key generated by the process described in Figs. 41A-41C;
  • Fig. 45 is a diagram of the form of the "plain text input" used in the PIN-inclusive ASCF generation process
  • Fig. 46 is a glossary of additional commonly used acronyms.
  • the present invention provides point-to-multipoint circuit switched connections between mobile terminal subscriber stations and a central base station.
  • Mobile users are able to listen to two-way conversations and to transmit using a push-to-talk mode of operation.
  • the MET includes all of the communication and control functions necessary to support communications from a vehicle or fixed remote site using the resources of the satellite network system.
  • Figs. 6 and 7 are basic block diagrams of the physical architecture and functions of the mobile earth terminal.
  • the basic functional diagram of Fig. 7 is implemented by baseband processing and RF electronics of Fig. 6.
  • a standard voice coder/decoder receives coded messages from the baseband processing and RF electronic system and decodes the message received from the satellite antenna unit for delivery to the interface unit that includes standard user interfaces.
  • Baseband processing and RF electronics receive satellite communications responsive with low noise amplifier (LNA) and output signals for transmission using the diplexer of the antenna unit Baseband processing and RF electronics also outputs signals for use with beam steering antennas as will be discussed blow
  • the mobile earth termmal is functional with antennas that are either steerable or nonsteerable .
  • the functional subsystems comprising the MET are shown m Fig 7 and include the user interface, transceiver, antenna, logic and signaling, power supply subsystems, and Position Determination subsystem.
  • the baseline MET will have a low gam directional antenna the antenna subsystem.
  • the satellite network system supports communications with METs using omnidirectional and higher gain directional antennas
  • the user interface subsystem provides the user interfaces through which the user has access to the services supported by the satellite network system.
  • the MET will be equipped with one or more of the devices or ports
  • the transceiver subsystem consists of a receiver and a transmitter
  • the transmitter accepts voice, data, fax and signaling signals and converts them to a modulated RF signal.
  • the transmit RF signal is routed to the antenna subsystem
  • the transmitter typically consists of the high power amplifier (HPA) , the upconverter with its associated frequency synthesizer, the modulators and the modules for voice, Fax, or data encodmg, multiplexing, scrambling, FEC encodmg, interleaving and frame formatting.
  • HPA high power amplifier
  • the receiver accepts modulated RF signals from the antenna subsystem and converts them mto voice, data, fax or signaling signals as appropriate
  • the voice, data and fax signals are routed to the user interface subsystem
  • the receiver typically consists of the downconverter with its associated frequency synthesizer, the demodulator, and the modules for frame de-formatt g, de-interleavmg, FEC decoding, descramblmg, demultiplexing and voice, Fax, or data decoding.
  • the transceiver communicates over one channel in each direction at any one time.
  • the transceiver subsystem will typically consist of only one receiver and one transmitter.
  • the MET may also incorporate a pilot receiver for antennas and frequency tracking purposes, or a complete receiver dedicated to the continuous reception of the signaling channel from the Group Controller.
  • the antenna subsystem provides the MET interface to the satellite network and is responsible for receiving the RF signal from the satellite and transmitting the RF signal generated by the MET towards the satellite.
  • the subsystem typically mcludes an antenna which may be either directional or omnidirectional, a diplexer, a low noise amplifier (LNA) , an optional beam steering unit (BSU) if a directional antenna is used, a device such as a compass or an inertial sensor for the determination of the orientation of the vehicle, and an antenna for the position determination receiver.
  • LNA low noise amplifier
  • BSU beam steering unit
  • the logic and signaling subsystem acts as the central controller for the MET. Its basic functions are to initialize the MET by performing a self test at power up and control, based on a resident system table, the acquisition of one of the METs assigned outbound signaling channels from which updated system information and commands and messages from the GC are derived
  • the logic and signaling subsystem sets up and configures the transceiver for the reception and transmission of voice, data, fax or signaling messages as appropriate
  • the logic and signaling subsystem also handles the protocols between the MET and the FES and between the MET the GC via signaling messages, and checks the validity of the received signaling messages (Cyclic Redundance Check (CRC) ) and generates the CRC codes for the signaling message transmitted by the MET
  • CRC Cyclic Redundance Check
  • the logic and signaling subsystem also interprets the commands received from the local user via the user interface subsystem (e.g on/off hook, dialled numbers, etc.) and take the appropriate actions needed, and generate
  • the power supply subsystem provides power to all other subsystems
  • the external voltage source to which this subsystem interfaces depends on the type of vehicle on which the MET is mounted (e g. 12/24 Volts
  • a standard receiver such as a GPS or a Loran-C receiver is also provided for the determination of the position of the vehicle This information is used by the logic and signaling subsystem for beam steering (if used) or for applications such as position reporting.
  • the position determination system is implemented externally to the MET and interfaced through a dedicated data port m the user interface subsystem
  • the function of the Remote Monitor System is to continuously monitor the activity on each GC-S channel and to monitor the activity with the downlink L-band spectrum the beam m which it s located
  • An RMS will be located m every beam carrying satellite network traffic
  • An RMS may be a stand alone station or collocated with the NCC or an FES
  • the RMS is controlled by the NOC and communicates via leased lines or the interstation signaling channels if collocated with an FES.
  • the RMS detects anomalous conditions such as loss of signal, loss of frame sync, excessive BER, etc. on the GC-S channels and generates alarm reports which are transmitted to the NOC via the leased lme interface. In addition, it monitors BER on any channel and power and frequency m any band as instructed by the NOC.
  • STS is to provide commission testing capability for every channel unit m a FES and to provide readiness testing for the Off-Lme NCC.
  • the STS is collocated with and controlled by the NOC and will comprise one or more specifically instrumented METs
  • the STS provides a PSTN dial-up port for making terrestrial connections to FESs to perform MET to terrestrial end-to-end testing.
  • the STS also provides a LAN interconnection to the NOC to provide access to operator consoles and peripheral equipment.
  • the MET combines three different features for the delivery and transmission of voice and data These three features include: the ability to initiate and transmit a data call, the ability to initiate and transmit a facsimile digital call, and the ability to roam between satellite and terrestrial based wireless communication systems.
  • the followmg documents, representing applicable transmission protocols, are hereby mcorporated by reference: EIA/IS-41B Cellular Radio Telecommunications Inter-
  • MSS Mobile Radio Service
  • CUG User Group
  • the system behaves like a radio multi-party lme Public services and law enforcement agencies are typical users of this service, which is normally provided by either traditional terrestrial radio networks or by the more recent trunked radio systems
  • These trunked systems generally m the 800-900 MHz band, provide groups of end users with virtual private systems by assigning frequencies to CUGs on a demand basis
  • the Net Radio service is meant to be the satellite equivalent of terrestrial trunked systems ("trunking" for short) , and could be pictured as a "Satellite Trunked Radio Service", or "Satellite Trunking".
  • the Net Radio service provides the capability described in the previous paragraph in a cost effective manner as one shared satellite demand period circuit per CUG is utilized rather than one circuit per mobile user, the cost per mmute of a group conversation would be much less expensive to the owner of the group, and as the call set-up time for one shared circuit per CUG compared to an MRS multi-user conference set ⁇ up time is likely to be more acceptable to a group end user/operator, who normally expects to be able to talk as soon as the handset/microphone is taken off-hook.
  • An overview of the MSS system with Net Radio service is illustrated Fig 8.
  • Fig 8 illustrates the basic concept and elements involved in establishment of communications and control in the Net Radio system.
  • METs access the system via one or more L-band beams. Each beam contains one or more signaling channels for network control and call establishment and a number of communications channels for provision of Net Radio services to METs.
  • the L-band frequencies are translated to Ku-band frequencies by the satellite 12.
  • the Network Control Center 14 is responsible for the real time allocation of channels to support Net Radio calls.
  • the base Feederlink Earth Station 16 is responsible for re ⁇ transmission on the outbound channel of the MET transmissions received on the inbound channel, control of the Net Radio call, and interfacing the Net Radio call to terrestrial private networks.
  • a subscribing organization may comprise a number of METs grouped by their communication needs.
  • a virtual private communication net is established for each of these groups or subgroups .
  • the base FES 16 can interconnect the Net Radio call to terrestrial private networks so that a dispatcher located within the private network can participate in the conversation.
  • a Dispatch facility may be directly connected to the base FES 16, or may use leased PSTN or dial-up access, or may use a Mobile Radio Service (MRSA) circuit.
  • MRSA Mobile Radio Service
  • the Net Radio MET operates in CUG and receives voice transmissions from all other MET users in the same CUG, and the base FES.
  • the MET supports Net Radio service on a single demand period circuit per beam, which is shared by the entire CUG.
  • the MET requiring communications will be given the Net ID for the net and smce different nets may be necessary for different purposes, the MET may be given a number of different NET IDs.
  • NET IDs may represent organizational groups such as fleets or sub-fleets
  • NET IDs may represent functional groups such as a command unit which draws on mobile users from more than one fleet or sub-fleet NET IDs may represent geographic configurations such as an east or west area, or both.
  • a mobile user requests a channel on a Push-To-Talk
  • the MET receives an assignment of demand period satellite resources consisting of an outbound channel frequency and an inbound channel frequency relevant to the particular NET ID (per defmed CUG beam) .
  • the mobile user is alerted by a tone when the channel is available and the base FES manages the contention on the communications channel. Since the base FES retransmits the signal received from the mobile, the MET operates m a half duplex PTT mode, turning off the speaker while the microphone is engaged. When the user releases the PTT, the MET ceases transmission. On receipt of a release message from the base FES, the MET retunes to the signaling channel Figs.
  • FIGS. 10A-10C are flowcharts of the overall process conducted by the various components m establishment of communications and control m the Net Radio system.
  • a mobile earth termmal registers in step S2 and the user of the mobile earth terminal selects a particular net to establish voice communication therewith m step S4.
  • the user then activates the push-to-talk (PTT) button of the MET m step S5.
  • PTT push-to-talk
  • step S6 the MET sends the net number to the communication ground segment.
  • the communications ground segment receives the net number, checks the message for transmission errors, validates the specific MET user and also validates the requested net group in step S8.
  • the communications ground segment allocates a specific frequency for the net group and broadcasts the message to the net group informing the net group of the allocated frequency m step SIO.
  • the group controller m the communications ground segment will also send the net frequency to the feeder link earth station in step S12.
  • the METs that are idle, powered and logically consistent with respect to monitor codes and lock discussed below will tune to the net frequency indicated by the communication ground segment.
  • Channel assignment is thereupon completed and no further validation for the net group is performed in step S16.
  • a scrambling vector is next used to permit additional METs to join the selected net group in step S18. All METs are assumed to have joined the net group m step S20.
  • CGS will continue to broadcast NET group activation mformation at predetermined time intervals while the
  • NET group is active.
  • the MET user which initiates the Net Radio call is considered to be the current speaker m step S22 permitting the initiator to communicate with the various MET users that have joined the net group.
  • MET monitors whether a dispatcher message has been received in step S24, and if so the current speaker is set to the dispatcher, and the communication is broadcast to all METs in the NET group m step S26.
  • the MET also monitors receipt of the priority message step S28, and if a priority message is received, sets the current speaker to the identifier of the priority MET, and the communication is broadcast to all METs m the NET group m step S29. If no dispatcher message or priority message is received, the MET also monitors whether the current speaker is active in step S30. If speaker is active for the requisite period of time, the MET also determines whether the push-to-talk button has been released in step S32.
  • the current speaker is removed by the communications ground segment step S34, and the current speaker is set to vacant in step S36.
  • the communication ground segment will then notify the METs in the net group that the speaker is vacant m step S38.
  • the METs will then be permitted to initiate a request to be the next current speaker.
  • the communications ground segment Upon receipt of the first valid reque ⁇ t from a MET to be the next speaker m step S40, the communications ground segment will assign the new speaker to that particular MET m step S42. If, however, no request from a MET is made to Pe the next speaker, the communications ground segment will determine whether or not the hang timer has expired m step S44. If the hang timer has expired, the communications ground segment will release the call to the METs of the net group in step S46.
  • the feeder link earth station will also initiate a call release to the ground controller in step S48 and the ground controller will release the frequency channel which was bemg used for the net group m step S50.
  • the MET supports the service categories for Net Radio listed in Fig. 11.
  • MSS will support addressing methods that permit private communications between a mobile end-user and groups or sub-groups of end users, or an individual, where the individual is part of the same group.
  • NET IDs are utilized, where a NET ID can represent either a group, sub-group or individual.
  • MSS supports addressing methods that permit a mobile end user to engage in a private conversation with another mobile where the called mobile is part of the same virtual network as the calling mobile.
  • the MET monitors the NET Radio Channel Assignment SUs (NRCHA_SU) s on the GC-S channel for those containing any of its stored NET IDs and, if not engaged in a Priority call or set-up procedure, responds to assignments m accordance with the current setting of the call monitoring.
  • NRCHA_SU NET Radio Channel Assignment SUs
  • the MET provides a User ID display for the purpose of displaying the NET ID the MET is currently tuned to, and the MET DN of the current speaker.
  • the MET optionally displays an alpha-numeric display or user programmable label associated with a NET ID.
  • the MET When suitably equipped with a second receiver capable of continuously receiving the GC-S channel, the MET provides the user with notification of incoming calls, which the user may accept or reject
  • This section provides the formats of several SUs used by the MET that are additional for Net Radio service.
  • a separate section is generally provided for each channel type (GC-S, MET-SR, FES-C, MET-C)
  • the SUs transmitted on the GC-S signaling channel that are additional for Net Radio shall conform to the content and format specified in this section
  • the messages are required for Network Management and Call Control.
  • Fig. 12 identifies the additional GC-S messages each group.
  • the NID ⁇ SU is transmitted by the NCC to a MET on the GC-S channel
  • the NID SU is used to download a NET ID assignment to a MET subscribing to Net Radio Service .
  • the NID_SU has the format illustrated in Fig. 13.
  • the content of the NID-SU conforms to Fig. 14.
  • the NA message is used to allocate and de-allocate NET IDs assigned to a MET, to change a METs Directory Number (DN) , or to change the user defmed characteristics of a NET ID assigned to a MET.
  • DN METs Directory Number
  • NA_SU has the format illustrated in Fig. 15.
  • the content of the NA-SU conforms to Fig. 16.
  • the NRCHA message is used by the GC to broadcast the channel assignments to the METs for a Net Radio call.
  • the SU is broadcast on all GC-S channels defmed for the NET ID.
  • the NRCHA_SU has the format illustrated m Fig. 17.
  • the content of the NRCHA_SU conforms to Fig. 18. This message is rebroadcast on the GC-S channel every predetermined time interval (e.g., every 10 seconds) for the duration of activity of the NET communication.
  • the MET-SR messages are of the Call Control category.
  • the MET-ST messages are of the Network
  • Fig. 19 identifies the messages.
  • the MMA_SU is used by METs to acknowledge NID and NA messages received from the GC.
  • the MMA_SU has the format illustrated m Fig. 20.
  • the content of the MMA_SU conforms to Fig. 21.
  • NRACR_SU shall be used by METs to initiate Net
  • the SU message has the format illustrated m Fig 22
  • the content of the NRACR_SU conforms to Fig. 23
  • the messages are of the Call Control category Fig 24 identifies the messages m each group
  • the NRCR_SU shall be used to broadcast the NET ID to the METs durmg a Net Radio call and to indicate to the METs that the channel assignment for the Net Radio call is about to be released
  • the NRCR_SU has similar format and content as described above
  • the PTT_SU is used to request acces ⁇ to the inbound channel for a Net Radio call
  • the PTT_SU has the content conformed to Fig 25
  • the Response SU shall be used by the MET to respond to FES-C Command SUs received on the FES-C channel
  • the Response SU shall have the same format and contents as specified for the FES-C Command SU.
  • the Reserved field is reserved for future user defined requirements.
  • the MET timing requirements for Net Radio service are illustrated in Fig. 26.
  • Depressing the PTT switch while the selected NET ID is active and the speaker ID is vacant shall result in the transmission of a PTT_SU request on the communications channel followed by the transmission of voice frames in accordance with the standard MET call supervision procedures If the MET has not selected a NET ID and the MET is not active m a NET Radio Call, then the MET ignores the PTT request
  • Depressing of the PTT results m transmission of a PTT_SU only if the PTT is pressed after the speaker ID is equal to the vacant code or the METs DN. This will relieve congestion on the MET-C channel by adding a natural delay. If the MET user depresses the PTT before the speaker ID is vacant or matches the METs DN, the MET ignores the request .
  • Priority 1 service is granted to a MET, not based on the PTT, but only by activation of the Priority 1
  • Priority 1 Button Activation of the Priority 1 Button shall result m a Priority 1 call .
  • the user is given immediate access to the channel and retains it until he releases his PTT, is preempted by another Priority request generated by another MET user, or is preempted by a dispatcher PTT. If he wishes to make another Priority 1 transmission it shall be necessary to repeat the procedure.
  • the re-transmitted signal appears to the MET user as a delayed echo where the delay time is the double satellite link trans i ⁇ sion delay time. For this reason, the speaker is disabled while the user is talking.
  • the MET operates in half duplex from the user's viewpoint, but operates in full duplex over the satellite channels.
  • MSS Network Management assigns each communication net a Net Radio Identification (NET ID) number when the subscribing organization defines the net.
  • a MET is also assigned a number of NET IDs to use.
  • the MET stores in non-volatile RAM a GSl code for Net Radio service. The MET uses this G ⁇ I in selecting a GC-S channel while providing Net Radio service.
  • the MET also stores a directory number (DN) with a maximum of 4 digits.
  • the MET DN is downloaded to the MET at the completion of the commissioning process. If the MET receives an NA_SU with operator field equal to 3, the
  • MET stores the specified DN as its new DN.
  • the MSS Network Management assigns a unique 16 bit access security code to each NET ID defined.
  • the MET uses the NET access security code (NET ID ASK) to determine a standard scrambling vector used to initialize the channel unit scrambler for transmit and receive Net Radio calls.
  • the MET determines the scrambling vector using as input: the NET ID Access Security Key (ASK) the transmit Frequency Assignment the Receive Frequency Assignment.
  • a Net Radio subscriber can customize the organization of communications nets.
  • User defined NET ID attributes, a NET ID Tag number, and a Monitor code, are associated with the NET ID for this purpose.
  • Tag number is used to designate a selector position, or memory location to "tag" the NET ID to.
  • the MET operator sets the selector switch to a position, the MET uses the NET ID with the Tag number that corresponds to the selector position. This permits a CUG to setup all METs with the same selection positions for emergency nets for example.
  • the monitor codes are identified in Fig. 27 and are used to control which channel assignments the MET responds to.
  • the MET receives a channel assignment to a NET ID other than the one that was just tuned to. If the MET tunes to the new net, the operator may miss the next conversation on the previous net.
  • the monitor code permits the organization to setup nets which can reach entire fleets, or emergency teams even though all member METs have not selected that NET ID. In this case a monitor code for a required response is associated with the NET ID.
  • a Net Management System permits a Net Radio subscribing organization to customize their communication nets by assigning NET IDs to METs, changing NET ID assignments, or modifying the user defined attributes of a NET ID assigned to a MET. These changes are made by contacting or interfacing with customer billing support sy ⁇ tem/personnel .
  • the NMS enters the changes in the NOC customer configuration database.
  • the NOC disseminates this information to the NCC, which downloads the changes to the MET "over the air" from the GC-S channel.
  • the MET uses acknowledged MGSP message pairs for Net Radio MET management .
  • the MET Upon receipt of a NID SU addressed to it, the MET de-encrypts the NET ID NRASK using the METs ASK and RTIN, and stores that NET ID and the NRASK associated with the NET ID in non-volatile memory.
  • the MET then sends the MMA SU to the GC .
  • the MET stores multiple NET IDs, and an ASK is stored with each NET ID.
  • the MET Upon receipt of the NET ID Attribute SU, the MET performs operations indicated m the SU. The MET sends the MMA SU to the GC. The MET examines the Tag number contamed in the NET ID Attribute SU (NA_SU) and, provided the Operator field equals a predetermmed number, uses this number to determme the Tag position of the NET ID Selector switch to associate with that particular NET ID. For example, for a Tag number of zero the MET stores the NET ID in Tag location 00, which is reserved for Private Mode. If the Operator field m the NA_SU equals a predetermined number, for example 1, the MET erases the specified NET ID from memory.
  • NA_SU NET ID Attribute SU
  • the MET supports the following responses to the Monitor codes contained m the NA_SU.
  • the MET provides a means for the user to select one of the NET IDs and "lock-on" to it. When so selected, the MET does not respond to the NET ID assignments with monitor code 00 or 01, but responds to assignments with 11 code
  • the sequence of information exchanged between the MET, GC, and FES is for the purpose of demand period circuit assignment for Net Radio service, Private Mode service, Priority 1 service and Broadcast service calls
  • a call is described five parts; channel assignment, call establishment, call monitoring, call supervision and call release.
  • Channel assignment includes the network access procedures. Call establishment mcludes the procedures followed by the
  • Call monitoring mcludes the procedures performed by the MET durmg a call.
  • Call supervision includes procedures, performed by the FES, which provide contention resolution for MET access to the inbound channel.
  • Call release mcludes those procedures used by the FES to terminate a call and release the demand period circuits .
  • METs place and accept voice calls to/from members of the closed user group and a private network connected at a base FES.
  • the GC controls access to the satellite resources.
  • the base FES provides the Net Radio function of re-transmitting the mobile transmissions so that all member METs participating in the call can hear both sides of the conversation.
  • the FES provides access to the private network.
  • MET originated Net Radio calls are established using the sequence of messages shown in Fig. 28.
  • the protocol employed is as specified in the event tree m Fig. 29.
  • the GC verifies, based on the requesting MET RTIN that: the MET i ⁇ an operational Net Radio user; the MET is authorized to originate a Net Radio call using the NET ID included m the NRACR_SU; the required satellite capacity is available; the call type m the NET ID data base file is for
  • the GC verifies that the MET which requested the Net Radio call is in a beam included for the NET ID. If for any reason the call cannot be completed the GC sends a Call Failure SU using MGSP to the mobile terminal with the cause of failure mdicated in the cause indication parameter.
  • the GC determines that the call can be completed it will select frequency assignments for a FES-C communication channel and a MET-C communication channel and format a NRCHA SU with the NET ID for the call, and the call type set to Net Radio service.
  • the FES begins transmitting Net Radio SUs (NR_SU) using the In-band signaling mode.
  • the NET ID and requesting MET Directory Number are mcluded in the NR_SU.
  • the FES starts the Lost Speaker timeout (Nominally, for example, 3.5 sees) .
  • the FES also connects the Net Radio call to a dispatcher, as appropriate.
  • the MET Upon reception of the NRCHA_SU on the GC-S channel, the MET stops timer T M 24 and checks the call type. For Net Radio service call types, the MET tests the NET ID to determine what action to take. If the NET ID received matches one of the NET IDs assigned to the MET and if one of the following conditions is true, the MET accepts the Net Radio channel assignment and tunes to the assigned frequencies. If the NET ID does not match any NET ID assigned to the MET, or if none of the followmg case is true, then the MET ignores the NRCHA__SU and remains tuned to the GC-S channel.
  • Case 1 The Monitor code for the NET ID indicates a mandatory response.
  • Case 2 The Monitor code for the NET ID mdicates a conditional response and the condition criteria permit the MET to respond to the assignment . If the MET accepts the Net Radio channel assignment, then it alerts the user to the Net Radio call with appropriate audio and/or visual displays. The MET then starts timer T M 1. (Nominally, for example, 10 seconds) . If timer T M 24 expires, or a call failure is received, the MET indicates call failure to the user. Upon acquisition of the FES-C channel, the
  • MET stops timer T M 1 and decodes the NR_SU using the scrambling vector determmed from the Access Security Key. If the MET has a Net Radio call request outstanding, it verifies the NET ID and confirms that its user's Directory Number matches the Speaker ID. If there is no outstanding request, the MET only verifies the NET ID.
  • the MET tests the Speaker ID and if it matches its DN, it generates an audio and/or visual alert to the user and enable transmission. If T M 1 expires or the
  • the MET indicates call failure to the user and retunes to the GC-S channel.
  • MET Call Monitoring defines the procedures followed by a MET while assigned to a Net radio call .
  • the MET monitors the FES-C channel and operates timers on loss of the carrier.
  • the procedures determme when to permit PTT request ⁇ , disable transmi ⁇ sion, or re- tune to the GC-S channel.
  • a MET follows the call monitoring procedures specified herein and a ⁇ shown in Fig. 31.
  • the MET Upon accepting the NRCHA_SU the MET starts timers T M 20, the Lost FES-C channel timeout (Nominally, for example, 10 sees) , and T 22, the Transmit Inhibit timeout (1 superframe) .
  • the MET monitors the FES-C channel and generally only enables transmission if all the following conditions are true: the MET is in receipt of the FES-C channel, indicated when timers T M 20, and T M 22 are not expired; the MET is a member of the NET ID; the Speaker ID is the vacant ID or is equal to the MET user' s DN; the user initiates PTT ⁇ ignaling.
  • the transmitting MET continues transmitting provided all of the following conditions are true: the MET is in receipt of the FES-C channel, indicated when timers T ⁇ .20, and T M 21 are not expired. (T M 21 is defmed MET Call Supervision Procedure below) ; the current speaker as saved by the MET (see below) matches the MET's DN; and the PTT remains active.
  • the MET tests for a valid subframe at each FES-C subframe interval. When the MET receives a valid subframe, the MET restarts timers T M 20 and T M 22 A valid subframe is a voice subframe or a subframe having a message type recognized by the MET as a Net Radio message type and no errors are detected in the packet .
  • the MET restarts timer T M 21, "loss of speaker status timeout".
  • the MET tests the NET ID. If the NET ID is not valid for the MET, the MET shall retune to the GC-S channel. If the NET ID is valid, the MET saves the Speaker ID as the current speaker If the Speaker ID matches the MET's
  • the MET confirms, or maintains it's status as the "speaker". If the Speaker ID does not match the MET's DN, the MET ceases transmitting, if it was transmitting, and negates it's status as the speaker. If the subframe received is a Net Radio Call
  • the MET ceases transmitting and retunes to the GC-S channel.
  • the MET checks its speaker ⁇ tatu ⁇ . If the MET ha ⁇ the speaker status it ignores the timeout and continues transmitting. If the MET's speaker status is negated, it inhibits further PTT requests until all of the conditions listed above to enable transmission are satisfied.
  • the MET On expiration of timer T M 21, the MET stops transmitting, and negates or clears it's status as the current speaker. The MET indicates to the user that transmission has ceased. The MET remains on the assigned Net Radio channel. On expiration of timer T leverage2C, the MET retunes to the GC-S channel. MET Call Supervision Procedure
  • MET call supervision defines the procedures followed by a MET when the PTT button is pressed or released.
  • the procedures, together with the FES Net Radio procedures provide contention resolution of the inbound channel.
  • the MET accesses the MET-C channel for transmi ⁇ sion when the PTT is activated by the user in accordance with the MET call monitoring specified above and the call supervision specified herein, and by the event tree given in Fig. 32.
  • the MET transmits a PTT_SU using the In-band signaling mode for one frame as shown in Fig. 33 until an NR_SU is received with the Speaker ID not equal to the vacant code.
  • the PTT_SU mcludes the MET user's DN and the NET ID.
  • the MET then switches to voice mode and starts timer T M 23, the contention window timer (Nominally, for example, 1 second) .
  • the MET continues transmitting on the MET-C channel and monitoring the FES-C channel.
  • the MET tests the Speaker ID. If it matches the MET's DN, the MET saves the Speaker ID as the current speaker. The MET is then confirmed as the speaker. If the Speaker ID does not match the MET's DN, the MET ceases transmitting. The MET saves the Speaker ID as the current speaker. The MET negates or clears its speaker status .
  • the MET detects voice mode subframes on the FES-C channel instead of In-band signaling subframes, it assumes that these voice frames are either its own, or the dispatcher's and that the Speaker's ID SU was missed. In this case the MET continues transmitting. An NR-SU is sent to the MET in the next superframe . If an NR SU with the MET's DN as speaker ID is not received before the expiration of T M 23, the MET ceases transmitting. The MET then negates its speaker status. When the MET is confirmed as the speaker, the MET starts timer T M 21, the Lost Speaker Status timeout (Nominally, for example, 3.5 sees) . In addition the
  • MET disables passing voice output to either the extended speaker or the handset speaker.
  • the MET continuously transmits while the PTT button is active and conditions specified in the MET call monitoring procedures are met .
  • the MET finishes transmitting any voice subframes remaining in the buffer, and then switches to In-Band signaling mode as shown in Figs. 33 and 34.
  • the MET transmits one frame using the In-band
  • the PTT_SU identifies the MET user's DN and the NET ID and the PTT Relea ⁇ e Code.
  • the MET then ceases transmitting, but remains tuned to the net radio frequencies, and continues to monitor the FES-C channel for the NET ID in accordance with the MET call monitoring procedures. After the user releases the push to talk, the MET waits for a time equal to or greater than the delay time before enabling the loudspeaker again.
  • the MET tuned to the FES-C channel retunes to the GC-S channel and deactivates the Net Radio call indicator to the user.
  • the FES operates a hangtimer. When no activity has occurred for the hangtime duration, the FES releases the call.
  • the hangtimer, perceived by a MET user is shown in Fig. 35. Private Mode Service Call Procedures
  • the Network Control System procedures for MET originated Private Mode Service calls allow mobile CUG members to originate a call using a Net Radio channel configuration for the purpose of private communications with another member of the CUG. More than one NRC may be configured at a FES using the same NET ID. Thi ⁇ permits more than one Private Mode call to be in progre ⁇ at the same time .
  • MET originated Private Mode service calls are established using the sequence of messages shown Fig. 36.
  • the protocol employed is as specified for Net Radio service in the event tree given in Fig. 29.
  • a MET suitably equipped for Private Mode service formats and sends a Net Radio Access Request SU using MGSP on the MET-SR channel.
  • the NRACR_SU includes the NET ID private mode with the called DN. If no NET ID with a NET ID Tag number of '00 hex' has been assigned to the MET, the MET indicates call failure to the operator.
  • Radio service calls Once the GC determines that the call can be completed it selects the frequency assignments required for the NET ID and formats a NRCHA_SU with the call type field set for Private Mode and the MET FTIN number of the calling MET in place of the NET ID. The GC sends the assignment SU three times as for Net Radio service on the GC-S channel.
  • the GC formats a second Private Mode call type NRCHA_SU using the called MET FTIN number m place of the NET ID.
  • the GC sends thi ⁇ a ⁇ signment SU three times as for Net Radio service on the GC-S channels required for the NET ID. In the event there are no NRC's available to handle the call, the GC send ⁇ a Call Failure Message with no resources as the cause indication to the requesting MET.
  • a MET Upon receipt of the NRCHA_SU with the Private Mode call type, a MET compares it's FTIN with the FTIN in the NUCHA_SU. If the numbers match, the MET tunes to the as ⁇ igned frequencies . The MET then proceeds as for Net Radio service calls.
  • the MET uses the call establishment, call monitoring, call supervision and call release procedures as specified for Net Radio service calls.
  • the MET shall follow the Priority 1 procedures as specified in this section and as shown by the event tree given in Fig. 37.
  • the MET supports a Priority One mode of operation called the normal mode.
  • the MET takes one of three actions based on the state of the MET at the time.
  • the three states are:
  • the MET In the case where the Net Radio call is not m progress and the MET user has selected a Net ID, the MET originates the Net Radio Call.
  • the MET appends the Priority 1 code to the Net ID m the NRACR_SU.
  • the Net ID mcluded in the NRACR_SU is that which the MET user has selected.
  • the MET then proceeds with call establishment, call monitoring, call supervi ⁇ ion, and call relea ⁇ e a ⁇ for MET originated Net Radio service.
  • the MET responds as in case 1, except that the NET ID mcluded the NRACR_SU is retrieved from the NVRAM location specifically tagged by the MET user for this situation.
  • the MET tunes to the GC-S channel and sends a NRACR_SU with the Priority 1 code appended to the Net ID as for Case 1.
  • the MET sends a PTT_SU request with the Priority One code appended.
  • the GC Upon receipt of the NRACR_SU, the GC follows the call setup procedures as for MET originated Net Radio
  • the GC rebroadcasts the NRCHA_SU on all GC-S channels identified in the Net ID or that are active
  • the GC sends the
  • NRCHA_SU three times in three con ⁇ ecutive superframes as for Net Radio Service channel as ⁇ gnments.
  • the GC sets the Priority 1 code and mcludes the call identifier of the established call in the GC-I channel assignment message to the FES.
  • the requesting MET tunes to the assigned frequencies and proceeds as for MET originated Net Radio calls.
  • the MET presently transmitting on the MET-C channel detects that the speaker ID no longer matches its DN and ceases transmitting in accordance with the MET call monitoring procedures.
  • the Priority 1 requesting MET then proceeds as for Case 1.
  • Priority One Default Operations When the MET user initiates Priority One Default service via the Priority One button, the MET expediently performs the following actions:
  • the MET tunes to the GC-S channel and sends a NRACR_SU with the Priority One code appended on the corresponding MET_SR channel .
  • the MET retrieves the NET ID included in the NRACR_SU from a NVRAM location ⁇ pecifically tagged by the MET user for this situation.
  • the GC Upon receipt of the NRACR_SU, the GC follows the call setup procedures as for MET originated Net Radio
  • the GC rebroadcasts the NRCHA_SU on all GC-S channels identified in the Net ID or that are active (per dynamic beam allocation) .
  • the GC sends the NRCHA_SU three ti e ⁇ in three consecutive superframes as for Net Radio Service channel assignments.
  • the GC sets the Priority 1 code and includes the call identifier of the established call in the GC-I channel assignment message to the FES.
  • the requesting MET tunes to the assigned frequencies and proceeds as for MET originated Net
  • the MET transmitting on the MET-C channel detects that the Speaker ID no longer matche ⁇ its DN and ceases transmitting accordance with MET call monitoring procedures .
  • the MET proceed ⁇ with call establi ⁇ hment , call monitoring, call supervision and call release as for MET originated Net Radio service .
  • the MET beneficially includes the option of providing the service with a verification process that utilizes a security code.
  • the security code NET ID ASK is stored in the MET memory a ⁇ encrypted.
  • the MET recover ⁇ or derives the Net ID ASK from the encrypted
  • the 64-bit MET ASK and the concatenation of the 24 bit MET electronic serial number (ESN) and 10 "A" hexadecimal fill digits to form a 64-bit word are input into the DES encryption process.
  • Both the MET ASK and the DES encryption process are described detail in copending patent applications entitled “Fraud Detection and User Validation System for Mobile Earth Terminal Communication Device, " to William R. Tisdale and C.
  • a MET authenticates its identity upon each commissioning event, performance verification event, and call setup event.
  • the authentication process is based upon the use of an encryption function and a MET Access Security Key (ASK) to form an authorization code (the Access Security Check Field) from a random variable (the MET transmit and receive frequency assignments) at the beginning of each event.
  • the encryption algorithm is preferably the Data Encryption Standard (DES) defmed by ANSI X3.92- 1981/R1987, u ⁇ ed in the Electronic Codebook Mode (ECB) and is built mto both the MET and the NCC.
  • DES Data Encryption Standard
  • EBC Electronic Codebook Mode
  • Fig. 39 illustrates the ASK generation process u ⁇ ing a Seed ASK (SASK) provided by the MSS system operator, and a random number (EFTIN) .
  • SASK Seed ASK
  • EFTIN random number
  • the CRC-8 parity check algorithm is used to protect the integrity of the ASK.
  • the parity check is generated over all of the hexadecimal digits comprising the ASK.
  • the NOC provides a logically separate master database for the METID numbers (the MET electronic serial numbers) and the MET ASKs .
  • the NCCs maintain slave ASK databases, and also provide protection from access by NCC processmg functions other than the legitimate authorization processes.
  • the MET SASK is supplied to the MET user prior to commissioning.
  • the MET provides a "user friendly" means, using alphanumeric prompted, audible tones, and key strokes, for the user to enter the SASK mto the MET and verify its correctness.
  • the MET verifies the correctness of the SASK via the CRC-B parity check.
  • the MET uses the process detailed Fig. 39 to generate the ASK from the inputted SASK.
  • the MET stores the ASK in NVRAM. There is no means provided to read out or display the ASK once it is entered. Any attempted access to the ASK will preferably render the MET inoperable. It is possible, however, to enter or reenter the SASK at will
  • the NCC compute a 64-bit cipher text block by using the ASK stored m its secure database and the DES algorithm the ECB mode to encode a 64- bit input variable comprised of the 16-bit receive frequency assignment in the least significant bit position ⁇ , the 16-bit tran ⁇ mit frequency a ⁇ signment in the next least significant po ⁇ itions, the 24 Access Security Fill Bits, and the 8 most significant positions filled with the hexadecimal "A" (1010) characters.
  • the most significant 32 bits of the resulting cipher text block are designated the Access Security Check Field (ASCF) .
  • the lea ⁇ t significant 32 bits are designated the Secondary Security Check Field (SSCF) .
  • the Access Security Check Field and the Secondary Security Check Field generation process is depicted Fig. 40.
  • the Acces ⁇ Security Check Field is transmitted from the GC to the terminating FES in the SU.
  • the MET independently generates the Access Security Check Field using an identical process to encode the transmit and receive frequency assignments received m the MET Channel Assignment SU received from the NCC.
  • the MET transmits the Access Security Check Field to the FES the scrambling
  • the FES compares the MET and NCC generated Acces ⁇ Security Check Fields on a bit-by-bit basis. If the values are identical, the MET is declared authenticated, and the call setup l ⁇ completed normally. If the values are not identical, the MET identity is declared non-authenticated, and the FES terminates the call process. The FES sends a channel release message to the NCC, as well as the call record, w th authentication failure indicated as the call clearing reason.
  • the MET During commissioning or PVT, the MET generates the Access Security Check Field from the transmit and receive frequency assignments included in the Set Loopback Request SU received from the NCC, and returns it to the NCC the scrambling vector SU.
  • the NCC compares the locally generated value of the Access Security Check Field with the value returned by the MET on a bit-by-bit basis. If the values are identical, the MET identity is declared authenticated, and commissioning or PVT continues. If the values do not compare, the MET identity is declared non- authenticated, and the NCC terminates the process, declare PVT failure, and sends an authentication failure alert message to the NOC.
  • a "clear mode" is provided to facilitate system troubleshooting on an individual MET basis. This mode is invoked at the NCC (with suitable password control) , and causes the authentication system to accept and complete all calls for the specific MET, with or without a valid Access Security Check Field.
  • An “override mode” is provided that permits system operation without authentication, m case of failure or other problems. This mode is invoked at the NCC through operation of a hardware or software switch, with suitable protection (i.e., physical key, password) .
  • the "Authentication Subsystems" at the NOC (which maintains the master MET ASK database) , and at the NCC (which maintains the slave MET ASK database and generates the Access Security Check Field) are preferably both logically and physically separated from other NOC and NCC processors, and provide both physical and pas ⁇ word security to prevent unauthorized access to the MET ASK databases.
  • the NCC processors access the NCC Authentication Subsystem with the MET ID and the transmit and receive frequency assignments, and the NCC Authorization Subsystem returns only the MET ID and the Acces ⁇ Security Check Field.
  • a MET generally authenticates its identity upon each commissioning event, performance verification event, and call setup event.
  • the authentication process is based upon the use of an encryption function and MET Access Security Key (ASK) to form an authorization code (the Acces ⁇ Security Check Field) from a random variable (the MET transmit and receive frequency assignment ⁇ ) at the beginning of each event.
  • ASK MET Access Security Key
  • the encryption algorithm is preferably the Data Encryption Standard (DES) defined by ANSI X3.92- 1981/R1987, used m the Electronic Codebook Mode (ECB) , and is built into both the MET and the NCC DES is well known, well documented, and is m the public domain. Its performance is also well known, and is generally approved for U.S. Government application.
  • DES Data Encryption Standard
  • EBC Electronic Codebook Mode
  • the followmg relates to an enhanced or more detailed version of the fraud detection and user validation proces ⁇ .
  • the ASK for each MET l ⁇ independently generated at both the MET and the NOC/NCC using the DES algorithm.
  • the mputs to the generation process is a Seed ASK (SASK) provided by the MSS system operator, and a random number (EFTIN KEY) generated by the MET at the time of commissioning and used to encrypt the FTIN.
  • SASK Seed ASK
  • EFTIN KEY random number generated by the MET at the time of commissioning and used to encrypt the FTIN.
  • the SASK for each MET will be generated by the CMIS at the time of MET registration.
  • Fig. 39 illustrates the ASK generation process using the SASK and EFTIN variables
  • a standard CRC-8 parity check algorithm will be used to protect the integrity of the SASK.
  • the parity check is generated over all of the hexadecimal digits and incorporated into the SASK.
  • the NMS provides the processing capability necessary to generate the SASK and any needed parity check. Note that inclusion of the parity check bits as part of the SASK yields a 64 bit bmary word which is the length of key required by the DES.
  • the input to the parity checker is the information portion of the SASK.
  • the SASK is supplied to the MET subscriber prior to commissioning
  • the key distribution scheme is not a requirement of this specification.
  • the MET provides a "user friendly" means, using alphanumeric prompts, audible tones, and Key strokes, for the user to enter the SASK mto the
  • the MET verifies the correctness of the SASK as described below. If the SASK is incorrect, the user is prompted to enter the SASK again The MET does not enter the "Ready for Commissioning" state prior to entry of a valid SASK.
  • the MET uses the DES algorithm in the ECB mode to generate tne "active" ASK
  • the EFTIN KEY is extended to additional bits by falling tne leading positions and is used as tne plain text input to the algorithm
  • the SASK is used as the key
  • the resulting cipher text block is from the ASK Tne forms of the elements used in the key generation process are shown in Fig. 39. It is impos ⁇ ible for the MET to initiate recommissioning either with or without reentry of the SASK.
  • the CGS can selectively command at will a MET that has been detected as potentially fraudulent to reinitiate the commissioning process, thereby creating a new ASK and CCV. Therefore, if a fraudulent MET has gained access to CGS, the CGS can selectively "remove" the fraudulent MET upon detection.
  • the MET stores the SASK and the
  • ASK in NVRAM There is no means provided to read out or display either the SASK, or the ASK once it is generated and stored.
  • Fig. 41A is a flow chart of the keying process
  • Fig. 41B is an illustration of the keying process in the satellite communication system
  • Fig. 41C is a signal/data diagram of the keying process.
  • the MET subscriber registers or requests to become a subscriber of the satellite communication sy ⁇ tem in ⁇ tep S2.
  • Registration information is sent to CMIS and a customer service representative enters the registration information in the CMIS system that handles subscriber billing, contact and the like, in step S4.
  • CMIS then generates the Seed ASK which is supplied to the NOC/NCC and the subscriber/distributor of the MET prior to commissioning in step S6.
  • the subscriber/distributor enters the SASK into the MET in step S8, and the MET stores the SASK for commissioning in step S10.
  • the NOC/NCC stores the ESN and SASK and assigns a Forward Terminal ID (FTIN) for each MET in step S12.
  • the NOC/NCC also receives an FTIN Key from the MET which is a random number generated by the MET when the MET requests to be commissioned, and uses the FTIN key and the SASK to generate the ASK in step S14.
  • the NCC stores the ASK m step S16.
  • the NCC uses the FTIN Key and the FTIN to generate the EFTIN m step S18 and transmits the EFTIN to the MET.
  • the MET uses tne EFTIN and the FTIN key to recover the FTIN in step S20
  • the MET also uses the SASK and the FTIN Key to generate the
  • ASK m step S20 The MET then stores the ASK and FTIN in step S24 to be used later during the registration or call connect process.
  • the commissioning process is then completed in step S26, providing the necessary security codes in the MET associated with a specific
  • the NCC duplicates the process of MET ASK generation.
  • the NCC process is entirely automatic, and is protected from access by, the MSS system operators.
  • the NCC computes a cipher text block (see Fig. 40) by using the ASK stored m its secure database and the DES algorithm to encode an input variable comprised of the receive frequency assignment m the least significant positions, the transmit frequency assignment m the next least significant positions, the Access Security Fill Bits (transmitted m the Bulletin Board, see, for example, Fig 42) , and the most significant positions filled with predesignated characters.
  • the 32 most significant bits of the resulting cipher text block are designated the Access Security Check Field, and the least significant is designated the Secondary Security Check Field.
  • the MET also generates the Access Security Check Field from the transmit and receive frequency assignments mcluded in the Set Loopback Request SU received from the NCC, and returns it to the NCC m the scrambling vector SU.
  • the NCC compares the locally generated value of the Access Security Check Field with the value returned by the MET on a bit-by-bit basis. If the values are identical, the MET identity is declared authenticated, and commissioning or PVT continues. If the values do not coincide, the MET identity is declared non- authenticated, and the NCC terminates the process, declares PVT failure, and sends an authentication failure alert mes ⁇ age to the NOC.
  • the MET ASK is the DES 'key' and the concatenation of the ESN and fill bits is the DES 'Plaintext' .
  • the least significant 16-b ⁇ ts of the resultant cryptovariable is then exclusive- "or" -ed with the encrypted Net ID ASK to form the cleartext Net
  • the MET then proceeds to determme the scrambling vector used to initiate the MET scrambler for NET Radio calls
  • the generated NET Radio scrambling vector is applied to both the MET transmit and receive scrambling units.
  • the MET determmed the NR scrambling vector using the followmg process.
  • the NET Radio scrambling vector is, for example, the 15 least significant bits of the resultant 64-bit DES "ciphertext" output therefrom.
  • a MET wants to oin a NET Radio group, then the MET is able to enter the group via the scrambling vector.
  • the MET mcludes the capability of dual standby operation when configured, registered and commissioned for both MTS and NR service.
  • Dual standby operation is defined as MET operation whereby the MET responds to either MTS page requests or NR Channel Assignments as transmitted on the GC-S channel
  • the MET is not required to monitor the GC-S channel for service requests of another type while the MET is responding to a service request of either type.
  • This feature is user selectable: either MTS only, NR only, or Dual Standby
  • the MET determines whether an MTS call or NR call is desired via the appropriate entries by the MET user or by receiving the appropriate signaling units discussed previously.
  • the MET When the "MTS only" of the dual standby mode feature is selected, the MET will undertake the authentication process after the MET ASK has been generated The authentication process indicates that the MET is ready to ga access to CGS for voice/data communication using the real-time authentication process described hereinafter According to the authentication proces ⁇ , the Access Security Fill Bits are transmitted in the MET bulletin board The NOC operator can manually change this field to any desired pattern. It is recognized that when the Access Security Fill Bits are changed there will be a short period durmg which METs will attempt to acces ⁇ the system with Authentication Codes generated using the
  • the MET transmits the Access Security Check Field m the Scrambling Vector SU.
  • the FES compares the MET and NCC generated Access Security Check Fields on a bit-by-bit basis. If the values are identical, the MET identity is declared authenticated, and the call setup shall be completed normally. If the values are not identical, the MET identity is declared non-authenticated If nonauthenticated, the FES terminates the call process, and sends a channel release message to the NCC with authentication failure indicated as the call clearing reason. Upon receiving the channel release message with authentication failure as the call clearing reason, the GC generate an authentication failure event. The NCC treats this as an alarm condition.
  • NCC provides a real time display to the MSS operator console indicating that the call wa ⁇ failed due to authentication failure
  • a "clear mode” is provided to facilitate system troubleshooting on an individual basis This mode is invoked at the NCC (with suitable password control) , and causes the authentication system to accept and complete all calls for the specific MET with or without a valid Secondary Security Check Field.
  • An “override mode” is also provided which permits system operation without authentication, case of failure or other problems .
  • This mode is invoked at the NCC through operation of a hardware or software, with suitable protection (i.e , physical key, password) .
  • the "Authentication Subsystem" at the NOC/NCC (which maintains the MET ASK database) is both logically and physically separated from mother NOC and NCC processors, and which provides both physical and password security to prevent unauthorized access to the MET ASK databases.
  • the NCC processors access the NCC Authentication Subsystem with the MET ESN (RTIN) and the transmit and receive frequency assignments and fill bits
  • the NCC Authorization Subsy ⁇ te returns only the MET ESN, the Access Security Check Field and the Secondary Security Check Field.
  • a MET is required to authenticate its identity upon each request to invoke an advanced calling feature which redirects the source or destination of a call or adds participants
  • the MET mcludes the least significant ("right most") bits of the Secondary Security Check Field m the AFR SU ("Hook Flash") transmitted in an Advanced Features Request Sequence
  • the serving FES compares the these least significant bits of the Secondary Security Check Field received from the NCC in the Channel As ⁇ ignment
  • the FES denies the advanced features request, and provides a suitable indication, such as a tone or recorded voice announcement, to the MET subscriber.
  • the FES sends a reauthentication failure alert message to the NCC.
  • the MSS system provides for a Call Count Variable (CCV) in the authentication process.
  • the CCV is a count of calls made by each MET, and is separately and independently maintained by the individual METs and the NCC.
  • the CCV is a 16 bit binary number, and is set equal to the value of the least significant 16 bits of random EFTIN KEY when the MET is commissioned or recommissioned.
  • the CCV is incremented at the completion of each call setup.
  • the CCV is also incremented at the MET when the change from transmission of the Scrambling Vector SU to voice/data frames is made.
  • the CCV is also incremented at the NCC when the call Setup Complete SU is received from the serving FES .
  • the NCC adds (i.e., the logical XOR operation) the CCV to the least significant bits of the Secondary Security Check Field.
  • the resulting CCV Check Field is included in the Channel Assignment SU sent to the serving FES.
  • the MET independently generates a CCV Check Field using an identical process, and mcludes the result in the Scrambling Vector SU sent to the serving FES during call setup.
  • the FES verifies the MET CCV.
  • the FES declares the CCV to be authenticated if the absolute value of the error is equal to or less than a configurable threshold. Provision is made for selection of the error threshold by the NOC/NCC operators .
  • the nominal value of the threshold is zero, and the range is at least zero to 15 (decimal) . If the absolute value of the error is greater than the threshold, the FES declares the CCV non-authenticated.
  • the FES terminates the call process, and sends a channel release message to the NCC, with CCV authentication failure indicated as the call clearing reason.
  • the GC Upon receiving the channel release mes ⁇ age with authentication failure as the call clearing reason, the GC generates an authentication failure event. The NCC treats this as an alarm condition.
  • Figs. 44A and 44B are diagrams of this described authentication process using the authentication security key generated by the process described m Figs. 41A-41C.
  • the fraud detection and user validation system optionally includes an enhanced MET authentication process through the use of a Personal
  • PIN Identification Number entered by the MET subscriber at the initiation of each call
  • the PIN is not to be used for MET terminated calls.
  • the PIN is provided to the MET subscriber by the MSS operator and must be entered whenever the MET initiates a call.
  • NOC/NCC makes provision to enter and store the PIN in the MET ASK secure database.
  • the NOC/NCC software architecture makes provision for a "PIN REQUIRED" Flag to be mcluded m the data base for each MET, and m the calling sequence and software used to invoke generation of the Acces ⁇ Security Check Field by the Authentication Subsystem.
  • the PIN Required flag can be set by CMIS or the NOC operator. If the use of the PIN s required, the NCC authentication subsy ⁇ tem replace ⁇ the most significant
  • the MET undertakes the authentication process if it is the initiator of the NR call, or generates a scrambling vector for the NET Radio service using the MET ASK and the NR ASK to join the NET group
  • the MET will undertake either the authentication process indicating that the MET is ready to gam access to CGS for voice/data communication or the scrambling vector generation proces ⁇ indicating that the MET is ready to ga access to a NET Radio group.
  • the MET is able to advantageously utilize both the standard MTS voice service and the NET Radio service .
  • a Call Barring List is flagged as Include, the MET may only make calls to the numbers or NPAs on the list. Any other call would be denied. Conversely, if a Call Barring List is flagged as Exclude, the MET may make calls to any number or
  • Numbering plan area or phone number m the call barring list.
  • the values that appear in the list are the phone numbers or NPAs that the MET's restriction apply to.
  • the types of restrictions are dictated by the flag ⁇ for Include/Exclude and Inbound/Outbound Call Barring. Call Trap Flag
  • Service available on the MET There are four service types: voice data (2400 or 4800 baud) , fax, and alternate voice data (avd) .
  • voice data (2400 or 4800 baud)
  • fax fax
  • alternate voice data (avd)
  • a service record l ⁇ created with a single call type indicated.
  • This call type turn has a unique mobile identification number (min) associated with it
  • This field is a switch field used to support equal access to long distance carriers.
  • Constant used by the GC to validate the encryption/decryption algorithm This element is related to the ASK Commanded GSl
  • the set of resources that exist m the configuration most recently sent to or received from the NOC. This is assumed to be the actual configuration of the traffic bearing network at any given time.
  • the CGS is divided mto Control Groups that contam circuit pools, signaling channels, bulletin boards, METs, and VNs .
  • a MET may only belong to one Control Group.
  • the control Group as ⁇ ignment is based on the virtual network membership. All VNs a MET is a member of must be m the same control group.
  • Identifier for a specialized routing information used at the switch e.g., 1024 available cust groups per MSR. Dialing plans will be implemented for groups of customers through a Customer Group
  • VN VN selected if user does not specify VN durmg dialing. For METs that belong to only one VN, this can be populated with the VN ID the MET is assigned to by default.
  • This element is a characteristic of the MET Class.
  • CMIS will only have the MET Clas ⁇ ID that a particular METs equipment maps to. NE/SE originates this and other data that describes the
  • Event Type Definition :
  • MET features within a specific VN Identifies MET features within a specific VN.
  • Fixed feature ⁇ are set up during order processing and require no action by the MET user to invoke a feature.
  • MET activated features must also be set up durmg order processing but will only be available through some action on the part of the MET use durmg call process.
  • FIXED FEATURES include:
  • CB Call Barring
  • MET ACTIVATED (dynamic) FEATURES include:
  • CFU Call Forwarding Unconditional
  • CFB Call Forwarding Busy
  • CFC Call Forward Congestion
  • CTN Call Forward No Reply
  • Alternate Voice Data Operation allows a MET user to toggle between voice and data mode during a call. Requires that the call be initiated in voice mode. Only the MET user may toggle between voice and data. This requires a special service type in addition to the activation at set-up of the feature.
  • Conference calling (CC) allows a MET to communicate with multiple-parties including METs and PSTN concurrently.
  • Three Party Service (3PS) allows a MET to who is active on a call to hold that call, make an additional call to a third party, switch from one call to the other (privacy being provided between the calls) and/or release one call and return to the other.
  • MCT Malicious Call Trace
  • VM Voice Mail
  • ACC Alternate Accounts Charging
  • MET Call Barring Flags Definition Describe actions available to a user originating a call from a MET. These call Barring flags relate to specific types of calls at an aggregate level to mdicate if the MET can make or receive a call of a particular type. When this list indicates that an Inclusion or Exclusion to particular numbers or area codes is allowed, the values for those restrictions are indicated on a Call Barring FTIN Definition:
  • NOC generated time stamp used for NOC audit purposes .
  • Internal Transaction Id Definition NOC generated transaction is u ⁇ ed for NOC audit purposes .
  • CMIS will only have the MET Cla ⁇ s ID that a particular MET's equipment maps to.
  • NE/SE originates this and other data that describes the MET Class and sends
  • Mobile Servicing Region id (table) contams multiple MSA assignments for the MET.
  • the operator will input the MSR for temporary assignment Allows up to 1024 cust groups - At CGS startup there will be 1 MSR.
  • CMIS assigned unique MET identifier This can be a unique random number assigned to each MET registered for service This is a MET level characteristic set once for the MET regardless of how many services, etc. the MET has The MET ID is used by the NOC to identify METs. It does not have to be used withm CMIS as a key field MET ID cannot be updated once it has been assigned A
  • Carrier name is contamed CARRIER field.
  • Remote feature personal identification number A user is prompted for a p when attempting to use a remote feature.
  • Reverse Termmal Identification Number which is also the satellite electronic serial number on satellite only and dual mode cellular/satellite METs. This is a unique identifier assigned by manufacturer for each piece of equipment . Withm CGS processing the RTIN is used by the GC to signal the MET. Satellite Id Definition:
  • Satellite Id of current L-band beam The NOC populates this field based on MET commissioning.
  • each MET may have only one signaling priority regardless of the number of VN memberships it has .
  • the highest priority level is 0 and the lowest is seven.
  • TDM is the GSl
  • Telephone Number Definition Phone number associated with a call type (voice, data, fax, avd) in a given virtual network.
  • Trunk Access Priority Definition Describes action ⁇ available to a user receiving a call at their MET. Trunk Access Priority Definition:
  • Satellite trunk queuing priority used durmg network congestion. Determines access to channels.
  • a MET may have one voice, data, fax and/or avd service type.
  • Features and restrictions for those services are defined on the basis of the METs membership m that VN. If the MET required an additional instance of a service that it already subscribed to, (e.g a second voice number) , a second virtual network assignment would be required.
  • Features and restrictions for that second membership can be defmed with no relation to the existing VN membership, but all elements that relate to the MET level cannot change without a ripple effect to the other services VMS Instance Type
  • Vocoder version currently installed in the MET CMIS will only have the MET Class ID that a particular METs equipment maps to NE/SE originates this and other data that describes the MET Class and sends it to the NOC.
  • the set of resources currently being modified by the engineer This may be an existing, complete configuration which the engineer is modifying, or may be a new, partial (or initially empty) configuration.
  • ACU Antenna Control Unit
  • DAMA Demand Assignment Multiple Access db Database dbc Decibel Relative to Carrier dB decibels dBi dB Relative to Isotropic dBm dB relative to 1 milli watt dBW decibels relative to 1 watt
  • FCS Fading Channel Simulator FDMA Frequency Division Multiple Access
  • FEC Forward Error Correction FES Feederlmk Earth Station
  • LAPB Link Access Procedure using a balanced mode of operation LATA Local Access and Transport Area
  • Random Access Signaling Channel from Mobile Terminal to Group Controller MET-ST Time Division Multiple Access signaling channel from Mobile Terminal to Group Controller MF Multiple Frequency MFID Manufacturer Identification
  • MIB Management Information Base MIR Management Information Region MIRQ MT Initialization Request MIS Mobile Terminal Interface Simulator
  • NCC Network Communications Controller NCC Network Control Center NCC-RE
  • VAX Virtual Address extension (.proprietary name used by DEC fo some of its computer sy ⁇ tems)
  • VCN Virtual Circuit Number
  • Voice Frequency VLR Visitor Location Regi ⁇ ter
  • VN Virtual Network
  • VPN Virtual Private Network
  • X.25 physical layer interface for Data Terminal Equipment designed for interfacing to synchronous V-series modems to access data networks X.25 Specification for interface between Data Termmal

Abstract

Un système de communication mobile assurant la communication entre des utilisateurs multiples (10) dans une configuration de groupe fermé d'utilisateurs, comprend une pluralité de terminaux terrestres mobiles (TTM) (10) rattachés à un système satellitaire mobile (12). Le premier terminal terrestre mobile (10) sélectionne un identificateur de réseau (ID RESEAU) de groupe fermé d'utilisateurs, représentant un groupe RESEAU pour établir la communication vocale avec ce dernier et envoyer l'ID RESEAU à un dispositif de commande central (14). Ce dernier (14) reçoit l'ID RESEAU d'un premier TTM (10), valide l'ID RESEAU, attribue une fréquence au groupe reseau et diffuse le message à l'attention du groupe réseau l'informant de la fréquence attribuée. Le deuxième TTM (10) se règle sur la fréquence en réponse au message diffusé par le dispositif de commande central (14).
PCT/US1996/019165 1995-09-19 1996-11-27 Systeme perfectionne de service radio relie a un satellite WO1997020401A1 (fr)

Priority Applications (3)

Application Number Priority Date Filing Date Title
CA002238646A CA2238646C (fr) 1995-11-30 1996-11-27 Systeme perfectionne de service radio relie a un satellite
AU12763/97A AU1276397A (en) 1995-11-30 1996-11-27 Improved satellite trunked radio service system
US09/114,289 US6477370B1 (en) 1995-09-19 1998-07-13 Satellite trunked radio service system

Applications Claiming Priority (6)

Application Number Priority Date Filing Date Title
US774295P 1995-11-30 1995-11-30
US60/007,742 1995-11-30
US1420596P 1996-03-27 1996-03-27
US60/014,205 1996-03-27
US08/657,479 US5717830A (en) 1995-09-19 1996-05-29 Satellite trunked radio service system
US08/657,479 1996-05-29

Related Parent Applications (1)

Application Number Title Priority Date Filing Date
US08/657,479 Continuation-In-Part US5717830A (en) 1995-09-19 1996-05-29 Satellite trunked radio service system

Related Child Applications (1)

Application Number Title Priority Date Filing Date
US08/887,691 Continuation-In-Part US5790071A (en) 1997-07-03 1997-07-03 Method for determining orientation and attitude of a satellite- or aircraft-borne phased-array antenna

Publications (1)

Publication Number Publication Date
WO1997020401A1 true WO1997020401A1 (fr) 1997-06-05

Family

ID=27358434

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US1996/019165 WO1997020401A1 (fr) 1995-09-19 1996-11-27 Systeme perfectionne de service radio relie a un satellite

Country Status (3)

Country Link
AU (1) AU1276397A (fr)
CA (1) CA2238646C (fr)
WO (1) WO1997020401A1 (fr)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6058307A (en) * 1995-11-30 2000-05-02 Amsc Subsidiary Corporation Priority and preemption service system for satellite related communication using central controller
EP1056223A1 (fr) * 1999-05-25 2000-11-29 ICO Services Ltd. Système de communication par satellite ayant des groupes s'excluant d'utilisateurs
AU773827B2 (en) * 2000-11-10 2004-06-10 Ntt Docomo, Inc. Mobile communication method and mobile communication system
US6856603B1 (en) 1999-03-19 2005-02-15 Robert Bosch Gmbh Process, control center, and terminal equipment for transmitting messages to terminal equipment in a telecommunications system

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5303286A (en) * 1991-03-29 1994-04-12 Space Systems/Loral, Inc. Wireless telephone/satellite roaming system
US5394560A (en) * 1992-09-30 1995-02-28 Motorola, Inc. Nationwide satellite message delivery system

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5303286A (en) * 1991-03-29 1994-04-12 Space Systems/Loral, Inc. Wireless telephone/satellite roaming system
US5394560A (en) * 1992-09-30 1995-02-28 Motorola, Inc. Nationwide satellite message delivery system

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6058307A (en) * 1995-11-30 2000-05-02 Amsc Subsidiary Corporation Priority and preemption service system for satellite related communication using central controller
US6542739B1 (en) 1995-11-30 2003-04-01 Mobile Satellite Ventures, Lp Priority and preemption service system for satellite related communication using central controller
US6856603B1 (en) 1999-03-19 2005-02-15 Robert Bosch Gmbh Process, control center, and terminal equipment for transmitting messages to terminal equipment in a telecommunications system
EP1056223A1 (fr) * 1999-05-25 2000-11-29 ICO Services Ltd. Système de communication par satellite ayant des groupes s'excluant d'utilisateurs
WO2000072468A1 (fr) * 1999-05-25 2000-11-30 Ico Services Ltd Systeme de communication par satellite
AU773827B2 (en) * 2000-11-10 2004-06-10 Ntt Docomo, Inc. Mobile communication method and mobile communication system

Also Published As

Publication number Publication date
CA2238646C (fr) 2001-03-20
CA2238646A1 (fr) 1997-06-05
AU1276397A (en) 1997-06-19

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