Abstract: A network includes a system and a population of subscriber units. System satellites move in low earth orbits and form moving cells on the surface of the earth. A pattern of static areas that covers the service area of the system is defined in a map. The system discovers the static areas for the subscriber units. When an incoming call needs to be directed to a subscriber unit, the subscriber unit's static area is converted into identities of beams that form the cells that coincide with the static area. A ring signal is transmitted in only these cells. Subscriber units monitor area identification signals that identify the static areas coincident with the cells where the signals are transmitted. When the static area known by the system is not among the identified static areas, a subscriber unit engages in re-registration communications.

Abstract: An RF communications system for providing wireless telecommunication service to sixteen contiguous geographic sectors or cells. The system includes an antenna array having a plurality of antenna sites located at the corners of contiguous geographic sectors. The central antenna site has four directional antennas. The four corner towers each have three directional antennas. Each directional antenna illuminates an entire sector. The location of the antenna sites and the allocation of a frequency group for each sector minimizes RF interference.

Abstract: A mobile communications network comprises a PCN network (60-64) including a plurality of radio cells under the jurisdiction of an MSC (mobile-services switching center). One or more of said cells comprise a fixed base (60, 61) for a mobile subscriber (71). Location information regarding the fixed bases being stored in a fixed location register (FLR). When the mobile subscriber roams into such a fixed base location (60, 61) a respective service type is provided. In particular, the fixed base may be a business site (60) with a PABX network. When the mobile subscriber roams into the business site, calls involving him are routed via the PCN network or rather the base station controller (BSC) thereof, which is intelligent in that it has MSC functionality located thereat. Thus a mobile phone can act as a desk phone, with all the same services provided, whilst the mobile subscriber is within the business fixed base.

Abstract: A method for handling calls to a terminal in a mobile telephone system of the kind in which the call is handled by an ISUP/IAM message which has a static relationship between the address of the visitor location register in the network in which the terminal roams, and the unique terminal identity. If the visitor location register has no data record relating to the unique identity, an attempt is made to collect from the home location register of the called subscriber the data that is required to complete the connection, this data being stored in the visitor location register. If the attempt is successful and the called subscriber is active, the connection is set up in a known manner with the aid of this data.

Abstract: A local area network comprises a plurality of network interfaces with each network interface coupled to a station, the network interfaces further for exchanging data with each other. The local area network further comprises a distribution station for exchanging data with the network interfaces. The distribution station further receives load information of the network interfaces, and in response to the load information, transmits a channel distribution for the exchange of data between the network interfaces.

Abstract: A radio paging system includes one or more transmitters (12) for sending radio signals to pagers (14) within a paging service area (10). Receivers (22) are located within the service area to receive low power transmissions from the pagers. These receivers are coupled to omnidirectional antennas (24, 26) that are disposed in pairs to form a two branch diversity antenna system. Each pair of antennas is located in a cell that forms part of a four cell cluster (66), and each pair of antennas is located on an axis (42) running through its cell. The axes are selected to provide a high and uniform level of diversity gain throughout the cluster.

Abstract: A radio telephone which is capable of switching between operating through a land based cellular network and an orbiting satellite system is disclosed. First antenna and radio frequency circuits receive transmitted signals from the land-based network and form first conditioned signals for subsequent numerical decoding. Second antenna and radio frequency circuits receive transmitted signals from the orbiting satellite system and form second condition signals for subsequent numerical decoding. Numerical decoders process either the first condition signals or the second conditioned signals to provide an automatic frequency control signal. Reference frequency oscillators controlled by the automatic frequency control signal provide a reference frequency signal.

Abstract: A base transceiver station of a GSM type cellular network exchanges data by radio with mobiles in a specific geographical area or main cell divided into a plurality of sectors each corresponding to a specific portion of the main cell and each associated with a receiver having a directional antenna. The base transceiver station includes a single transmitter having an omni-directional antenna and providing the transmit radio coverage of all the sectors so that the data transmitted by the base transceiver station in the form of radio signals to a mobile in any sector is transmitted by the transmitter.

Abstract: A method and apparatus in a radio communication system (100, 101) provides simulcast control channels for a coverage area (500), and message channels transmitted in coverage zones (502) within the coverage area (500) on a time-division multiplex basis (FIG. 4). A first modulation technique generates (814, 816, 818) each of the message channels at a first average output power substantially less than a peak output power of a transmitter (202). A second modulation technique generates (806, 808, 810) each of the control channels at a second average output power approximately equal to the peak output power of the transmitter (202), thereby increasing usable coverage distance from the transmitter (202) for the control channel compared to the message channel. The control channels are allocated (FIG. 5) to the coverage zones (502) in a staggered geographic pattern such that reception of the control channels is maintained substantially throughout the coverage area (500).

Abstract: In a method of determining, in a cellular mobile radio system with more than one type of cell, which type of cell a mobile station is accessing, the management network of the system sends to the mobile station a signalling message (recognition message) in the form of a sinusoid whose frequency (recognition frequency) differs from a reference frequency known to or determinable by the mobile station. The difference, optionally a null difference, between the reference frequency and the recognition frequency is characteristic of the cell type. The mobile station determines the recognition frequency. The mobile station then determines the difference between the reference frequency and the recognition frequency. The mobile station then determines the cell type from this difference.

Abstract: Unauthorized use of a communication unit 102 in a wireless communication system 100 may be prevented by determining the location of the communication unit 102 each time it transmits an affiliation request or a service request. Knowing the location of the communication unit 102, the controller 101 can determine whether the location of the unit fits within a historical location pattern for that unit. If the location does not fit within the pattern, the controller 101 can deny the request or send an indication to a system manager 110 asking the system manager 110 to decide what should be done with this unit.

Abstract: A method of forcibly disconnecting a communications connection established between a mobile station and a mobile services switching network, depending on whether the communications connection initially allocated to the mobile station has deteriorated or that a call connection or a handover attempt has failed. With the intention of forcing the mobile station to relinquish the allocated channel, the network transmits to the mobile station a signal which activates a time monitoring process in the mobile station, which thereby sends an acknowledgement signal back to the network. When the network does not wish the mobile station to retain the allocated channel, a signal which would stop the time monitoring process is not sent to the mobile station, thereby resulting in the release of the communications channel. Also described is a mobile station which includes counter-circuits for effecting the time monitoring process.

Abstract: Resource controllers (14) within a multisite communication system (20) selectively and automatically assume primary (45) and secondary (53) control modes of operation in order to ensure that adequate communication resources are assigned throughout the system at necessary sites in order to include talk group members that are dispersed throughout the system.

Abstract: Transceiver frequency and optionally power level are allocated to a radio personal communications system which includes a base station connected to a wire telephone network and a cellular terminal operating within a region of a wide area cellular network to minimize interference between communications over the wide area cellular network and communications between the base station and the cellular terminal. The same cellular terminal may thus be used to communicate over the lower cost wire network when within range of the base station and over the wide area cellular network otherwise. The frequency for communications between the cellular terminal and the base station are optionally assigned by the operator of the wide area cellular network so appropriate frequencies and power levels can be assigned for base stations, to minimize same channel interference with the wide area cellular network.

Abstract: A system and method for adaptive-power control of a spread-spectrum transmitter of a mobile station operating in a cellular-communications network using spread-spectrum modulation. A mobile station transmits a first spread-spectrum signal. A base station has an automatic-gain-control circuit for generating an AGC-output signal, from a received signal. The received signal includes the first spread-spectrum signal and an interfering signal. The base station also has a correlator for despreading the AGC-output signal, a power-measurement circuit responsive to processing the received signal with the despread AGC-output signal for generating a received-power level, a comparator coupled to the power-measurement circuit for generating a comparison signal by comparing the received-power level to a threshold level, a transmitter for transmitting a second spread-spectrum signal, and an antenna.

Abstract: A cellular digital packet data (CDPD) system includes a mobile data base station (MDBS) configured to interface easily with an advanced mobile phone system (AMPS). The elements of the MDBS are arranged on modules and the functionality of the MDBS is divided among the modules to facilitate flexibility, compactness and quick expansion of the MDBS. To further facilitate compactness, the MDBS includes a transceiver/modem board which uses a single chip to carry out delta-sigma modulation. In order to maintain the integrity of CDPD transmission, a channel hopping scheme is used based upon avoidance of AMPS channel use. A distinctive protocol is used to encapsulate control/query/response data for transmission throughout the CDPD system. This protocol also facilitates easy control of each MDBS throughout the system.

Abstract: A method of and system for paging mobile stations within a cellular telecommunication system wherein the allocation of control channel paging capacity is optimized. Each page request for a mobile station received by the system is classified into a predesignated group based upon the characteristics of the request, such as the degree of certainty with which the location of the mobile is known and the origin of the page request. In accordance with the predesignated group to which the page request is assigned, each page request is assigned a paging extent designation to be associated with one or more page attempts and representing the geographic area within the system to which each page attempt is to be broadcast. A paging priority is then assigned to each page attempt based upon the previously assigned group characteristics and paging patterns. Each page attempt is executed within the system according to its designated priority.

Abstract: A method and apparatus for circuit-switched and single-user traffic channel packet data communication in a cellular radiotelephone system, including a base station and mobile data unit both operable for establishing either a circuit-switched data call connection or a single-user connectionless packet data traffic channel via a radio channel, and communicating packet data over the established radio channel.

Abstract: A wide-area-network (WAN) system and the operation thereof involves a plurality of local-area network (LAN) systems with mobiles, base stations and TRS switching systems, and a systematical WAN system for the TRS switching system having a LAN controller for several LAN systems, thereby controlling wireless transmission signal level, providing communication service even when the mobile moves, and designating the range of communication service available for respective mobile.

Abstract: The present invention relates to a mobile satellite communication system. It is the object of the invention to provide a mobile satellite communication system capable of monitoring a location of a mobile station by data on its absolute location on the ground L, in lieu of relative monitoring thereof with respect to satellite base stations, to thereby ensure an effective location registration and suppress an increase of traffic in communication lines arising from location registrations. The satellite base stations are each equipped with a navigation signal generator for issuing navigation signals. The mobile station detects its absolute location on the ground L based on the navigation signals received from the satellite base stations, and executes its location registration procedure by use of identification data (communication zone ID) associated with the communication zone in which it lies and which is determined by the thus detected absolute location data.

Abstract: A method and apparatus for controlling transmission power in a variable rate communication system is disclosed. The method disclosed provides for a closed loop power control method. A first remote station controls the transmission power of a second remote station by transmitting a rate dependent power control signal to the second remote communication station. Since only the second communication knows its transmission rate a priori, it must determine its course of action in accordance with both the received power control signal and the knowledge of its transmission rate. In the present invention, the power control system reduces the amount of overhead required by restricting the possible rate transition of the variable rate communication system.

Abstract: Transceiver frequency and optionally power level are allocated to a radio personal communications system which includes a base station connected to a wire telephone network and a cellular terminal operating within a region of a wide area cellular network to minimize interference between communications over the wide area cellular network and communications between the base station and the cellular terminal. The same cellular terminal may thus be used to communicate over the lower cost wire network when within range of the base station and over the wide area cellular network otherwise. The frequency for communications between the cellular terminal and the base station are optionally assigned by the operator of the wide area cellular network so appropriate frequencies and power levels can be assigned for base stations, to minimize same channel interference with the wide area cellular network.

Abstract: A combined radiotelephone and paging device (101), hereinafter the combined unit, normally operates as a radiotelephone. In response to a predetermined condition, the combined unit operates as a paging device. The predetermined conditions include low battery voltage and poor communication channel quality or a request signal from a remote transceiver (109) of the radiotelephone system. The paging system and the radiotelephone system may be independent communication systems or they may be a single communication system. The combined unit (101) and its unique switching characteristics allows the combined unit (101) to utilize the paging devices beneficial qualities of lower power consumption and broader service range to enhance the usefulness of a radiotelephone.

Abstract: A paging acknowledgement system is provided for communicating both (1) paging messages and (2) acknowledgement messages to confirm reception of the paging messages. The paging acknowledgement system includes at least one communications system, remote communications devices, and at least one MSC of a CMR system. In response to a paging message from a paging party, the communications system transmits data messages corresponding to the paging message via a communications link. The data message contains the type of data that is normally supplied with a conventional paging message and an acknowledgment code that uniquely identifies said data message. A remote communications device responds to a data message containing its particular address by transmitting an acknowledgment message containing the acknowledgment code to the MSC via a cellular network control channel of the CMR system. The MSC forwards the acknowledgment message to the communications system via a first communications link.

Abstract: The local access and transport area identification number (LATAID) of the area within which both the A- party and B-party of a call are located is indicated within all roamer routing messages. This information enables automatic call setup within a cellular network in the most cost effective manner which still complies with the interLATA carrier regulations.

Abstract: A wireline interface permitting a cellular telephone transceiver to originate and receive calls using both cellular and wireline services. The invention permits a subscriber unit to operate as a standard cellular telephone when it is disconnected from a land-based telephone line, and as both a full-featured telephone and a full-featured cellular telephone when it is connected to a wireline. A wireline interface circuit provides on/off hook, calling identification, and audio signal conversion functions on the wireline signals. A duplexed audio switch permits the audio signals provided to and from a cellular-type handset to be connected either to the cellular transceiver or to the wireline interface adapter, under control of the user. As a result, any handset-provided functions such as speed dialing or hands-free operation are available for use when operating on a wireline circuit as well as when operating on a cellular radio link.

Abstract: In a general frequency reuse data communications system including infrastructure 100 and a subscriber terminal 115 a method of acquiring a channel includes: fast scanning 199 a predetermined list of data channels to identify a fast scanned channel; intermediate scanning 200, when the fast scanned channel is not identified, the predetermined list of channels to identify an intermediate scanned channel where a channel from the predetermined list of channels is evaluated for a first time period; and slow scanning 500, when the intermediate scanned channel is not identified, the predetermined list of channels to identify a slow scanned channel where a channel from the predetermined list of channels is evaluated for a second time period.

Abstract: A universal radio (401) having an adaptive memory is used by field service centers to give a radio user immediate access to a radio system regardless of the model type of the user's defective radio (403) while the defective radio (403) is being repaired. An information set in the defective radio's memory is transferred into the universal radio's memory for subsequent independent operation of the universal radio in the radio system.

Abstract: A mobile radio communication apparatus includes a switch which outputs a strength of a received radio frequency signal or a power strength of a radio frequency signal in accordance with an input of a switch control signal supplied from a switch control circuit. The switch control signal is supplied during a transmission time slot allotted to the mobile radio communication apparatus by the base station so that the switch outputs the power strength of the radio frequency signals in the same period of the transmission time slot and the strength of a received radio frequency signals in the same period of an other time slot. The strength of the received radio frequency signals and the power strength of the radio frequency signals are supplied to an analog-to-digital converter which converts the applied signal into a digital signal and supplies the digitalized signal to a level detector.

Abstract: A method and apparatus for efficiently tracking the location of a mobile station in a cellular network, especially in cellular networks having nonuniform traffic distribution. A mobile station reports to a base station only upon entering selected reporting cells. When communication with a mobile station is desired, the station is searched for in the vicinity of the last reporting cell in which the station appeared. The vicinity of a reporting cell is defined as the set of all intersecting cells reachable from the reporting cell without passing through another reporting cell.

Abstract: A method for secure and prompt distribution of critical operational information to a wireless cellular or PCS subscriber station via wireless interface which includes the steps of generating operational information, storing the operational information into a first memory of a wireless base station, and transmitting at least a portion of the operational information stored in the first memory to a wireless subscriber station via a wireless interface at random times during an active conversation state of the wireless subscriber station. The operational information stored in a second memory register in the subscriber station is updated with the operational information transmitted from the first memory. Where at least a portion of new operational information is received by the subscriber station, a first update counter is incremented to reflect the number of operational information updates received by the subscriber station.

Abstract: A mobile call processing methodology and concomitant system based on ISDN/CACH-EKTS technology which can broadcast incoming calls to base stations (e.g., 1050) and which uses the ISDN/CACH-EKTS bridging technology to handle base station handoff of an established call. Each mobile user (e.g., 1041, 1042) is assigned a unique EKTS directory number as well as a unique call appearance identifier, which allows for the handling of multiple call appearances of the unique DN on a single base station. For a given mobile communication application, the central office (e.g., 1014) treats the base station as an ISDN/CACH-EKTS terminal.

Abstract: In a cellular system configuration, the location of a mobile station is determined from the acquisition of cellular network data pertaining to the mobile station, and the translation of such network data into a corresponding geographical position profile. The cellular system includes a mobile station locator entity for receiving from a mobile switching center the network data such as cell and/or sector ID and trunk group member number. The mobile station locator translates the network data into position information such as geographic coordinates (latitude and longitude), resolution (radius), and angle values for sectorized cells.

Abstract: In a cellular mobile radio network a limited number of available channels must be allocated among the various cells, and the efficiency of such allocation is highly variable with changing traffic conditions in the network. To solve this problem the invention determines all possible radio situations which may arise in the network, including the radio positions of a mobile station and occupancy of the various channels. The individual components of each possible radio situation are then compared with predetermined thresholds so as to reduce the multiplicity of such situations to a relatively small number of classified radio situations each of which has its own channel list allocated thereto. When a channel is requested for a mobile station, the relevant classified radio situation is determined and channel assignment is made from the channel list applicable to that classified situation.

Abstract: In a radiotelephonic process for locating mobile subsribers, a profile is created from data recorded in a recording means in the form of a first work file and obtained during the movements of a particular mobile subscriber during a first predetermined observation period, the data relates to a plurality of daily chronological periods spanning the first observation period and each period has a start determined by the time at which the mobile subscriber entered a location zone with a particular daily identity, and an end determined by the time at which the mobile subscriber left the location zone and entered another location zone with a different identiy. There is also disclosed a radiotelephonic installation for carrying out the process.

Abstract: The base stations (BS) in a multicellular, wireless telephone system are connected via trunk lines (VL) to a communication system (KS), particularly to a telephone private branch exchange. The base stations (BS) are arranged at such a distance from one another that synchronization information (si) wirelessly transmitted from one base station (BS) can be at least partially received in a neighboring base station (BS). Both the initial, wireless synchronization as well as the synchronization during operation are controlled by the communication system such that respectively one base station (BS) is synchronized to the synchronization information (si) transmitted from a neighboring base station (BS). Compared to a synchronization of the base stations (BS) via trunk lines (VL), these deviations due to running times and different processing speeds in the synchronization unit realized in circuit-oriented terms are avoided in the wireless synchronization.

Abstract: A cellular radiotelephone system is accessed by a cellular radiotelephone without requiring System IDentification (SID) comparison during access. Access is performed by eliminating a rescan of Access Channels during access and using the Combined Paging and Access Channel which was identified during initialization for system access. Alternatively, the Access Channels may be rescanned upon an access request and a comparison of the Digital Color Code with the initially scanned channels is made. If the compared Digital Color Code matches, the identified channel is used for system access regardless of its SID.

Abstract: A scanning technique that is preferential as to communication channels actually utilized in the past. A programmable queue is written with a communication channel identity code based on a predefined criteria, such as each time the channel is actually used. The preferential queue is scanned in association with all the remaining communication channel identity codes, thereby providing a weighting factor that is skewed toward the selection of channels that have experienced actual use. System identification codes utilized in a mobile radio complex are stored in the queue in accordance with a roaming function, and group identity codes are stored in the queue when scanning home channels of mobile radio systems to determine incoming calls.

Abstract: In a first coverage area of a geographically-based frequency-reuse communication system, at least two time division multiplexed communication resources are provided (109 and 111). It is determined whether the first coverage area is supporting no more than a predetermined number of communications (203). When the first coverage area is supporting no more than the predetermined number of communications, transmission of at least one of the communication resources is temporarily terminated (205).

Abstract: A method of controlling handoff in a telecommunications network is provided, the network including a land system and a plurality of mobile stations, the land system including a plurality of cells, the method comprising the steps of dividing each cell into a first region where evaluation of measurement values is performed and a second region where the evaluation of measurement values is not performed, performing an evaluation of measurement values when a mobile station enters the first region, and controlling the handoff based on the evaluation of measurement values.

Abstract: A random access method in a radio system having a plurality of radio stations and at least one base station serving the radio stations, in which the base station transmits an invoking message to the radio stations in a first time slot to grant the radio stations the right to send a random access message to the base station. One of the radio stations transmits a random access message containing a random identifier to the base station in a second time slot subsequent to the first time slot. The base station transmits a response message containing the random identifier to the radio station in a third time slot subsequent to the second time slot. In order to avoid allocating the same telecommunications resource for simultaneous use by more than one of the radio stations, the response message sent by the base station to the radio station in the third time slot contains the identifier of the second time slot.

Abstract: A mobile telephone system multiplexes plural voice traffic channels on a single carrier using a TDMA protocol. The capacity of the mobile telephone system is increased by assigning voice traffic capacity, not on a conversation basis, but on an information burst basis. In order to avoid compromising the voice transmission capacity, control signals (for the allocation and deallocation of both forward and reverse traffic channels) are sent using multiple diversity, i.e. both time and frequency. In addition, to increase the number of available control channels, a control channel comprises a sub-divided portion of an otherwise equivalent voice traffic slot. For reverse allocation requests, which are transmitted over a contention access channel, power diversity is used in addition to time and frequency diversity.

Abstract: A communications system and method of ordered borrowing which facilitates dynamic access to a global channel set that has been partitioned into subsets, with each cell of the system being assigned a particular subset of the channel set. The assignment of channel subsets is performed in such a way as to respect various constraints imposed by the physical layout. Calls originating in a cell are first assigned to the channels allocated to the base station of that cell, in an order determined by the cell. Once the allotted channels are exhausted, i.e. in the busy state, the cell attempts to borrow channels from those allotted to the base stations of neighboring cells in a specified order. The borrowing cell borrows a specified number of channels from each neighbor before returning to a particular cell to borrow additional channels. The channels borrowed from a neighbor are accessed in an order which is substantially the reverse of the order in which they are accessed by the owner cell.

Abstract: A receiver for being mounted on an automobile telephone or similar mobile station which is included in a cellular mobile radio communication system. The receiver has a high frequency amplifier for amplifying a received input wave, and a mixer for converting the received input wave to an intermediate frequency. The gain of the amplifier or that of the mixer is changed on the basis of the level of the field strength of the received input wave and whether or not the mobile station is communicating with a base station. The receiver enhances the reception sensitivity characteristic at locations where the reception field strength is low or the intermodulation distortion characteristic at locations where the field strength is high and intermodulation distortions occur.

Abstract: In a cellular mobile radiotelephone system having a plurality of cells providing radio coverage by a plurality of base stations and having a plurality of mobile stations, the location of a mobile station with respect to cell boundaries is identified using measurements, performed at the mobile station or at selected cells, of transmissions from the cells or transmissions from the mobile station. When a cell is found that meets a specified standard with respect to a call connection in progress according to a first radio-signal criterion, a handoff candidate cell is selected according a second different radio-signal criterion. When no cell is found that meet the specified standard, a cell is selected according to the first radio-signal criterion. Handoff to the selected cell is attempted if that cell is not presently handling that call. More particularly, the first radio-signal criterion may be signal strength and the second radio-signal criterion may be path loss.

Abstract: In a multi-site communication system, a communication unit (106) transmits a communication request (208) that includes information identifying the sites (100 and/or 101) where the user desires to communicate with members of his user group. Communication resources are allocated (308) using the communication request and current resource allocation for the user group.

Abstract: Apparatus and method for automatically generating an authentication key (A-Key) in a mobile station wherein the mobile station periodically receives random numbers from a base station, and automatically generates the authentication key from a received random number and from mobile station identification data stored in the mobile station. The mobile station identification data may include the electronic serial number of the mobile station, a user selected value, and a cellular system selected value. In addition, mixing registers may be utilized by an encoding algorithm, such as the CAVE algorithm, for encoding the random numbers and the identification data to automatically generate the mobile station authentication key.

Abstract: A method for supervising and controlling the information transfer between two or more categories of users of a data network with closed user groups. Users, belonging to a first category of users, constitute, together with a number of users belonging to other categories, a special closed user group. Within this group, the users belonging to the first category are given a certain first identity, whilst users, belonging to other categories of users, are given a certain second identity, different from the first identity. Transfer of information is only allowed firstly between users with the first identity and users with the second identity and secondly between users who belong to the same closed user group.

Abstract: In transmitting information over a cellular communications channel to an opposite endpoint, a modem's autorating routine is "data-driven." In particular, when the amount of information to transmit to the opposite endpoint is low, the modem's data rate is low e.g., 4800 bps, and the modem's ability to autorate upwards, i.e., fallforward, is disabled. However, when the amount of information to transmit to the opposite endpoint is high the modem's ability to fallforward is enabled so that the modem's data rate can increase to the highest permissible data rate for the cellular channel in order to transmit large blocks of information.

Abstract: A mobile communications system provides communications with mobile users in the interference zones of communications services having priority of use of the frequency band in which the mobile user operates. The frequency band has been previously allocated for use by the other services, such as fixed microwave service (FMS); however, by means of the invention, the mobile user is able to conduct communications operations on a subband or subbands in that frequency band. A position locating system determines the position of the mobile user and if the user is within an interference zone, the mobile user is assigned subbands for operation in the previously allocated frequency band that are outside the subbands of operation of the FMS. A memory accessible by the processor selecting the frequency band of operation of the mobile user includes descriptions of the transmit and receive interference zones of each FMS.