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Showing papers on "Base station published in 1989"


Patent
03 Aug 1989
TL;DR: In this paper, a test signal is sent by a base station at a suitable point in a communi-cation protocol, where the test signal can be associated with a query from a mobile unit having a message to send or with a contention polling message from the base.
Abstract: In an exemplary embodiment, a test signal is sent by a base station at a suitable point in a communi­ications protocol. According to the evaluation of the test signal transmission, a relatively high data rate or a lower more conservative data rate is selected by a mobile unit for the transmission of a relatively lengthy data message. The test signal can be associated with a query from a mobile unit having a message to send, or with a contention polling message from the base. Such test signal can be transmitted at the lower data rate where its transmission characteristics (e.g. signal strength, jitter or quality of transmission of known information) can be used to predict probable feasibility of transmission at the higher data rate, but most preferably the test signal is part of a high data rate contention poll which may alternate with a low data rate contention poll.

366 citations


Patent
Jan-Erik Uddenfeldt1
11 May 1989
TL;DR: In this paper, the authors proposed a method in which the responsibility for transmitting message information to a mobile station is handed over from a first base station transmitter to a second base station transmitters.
Abstract: The invention relates to a method in mobile radio systems in which the responsibility for transmitting message information to a mobile station is handed over from a first base station transmitter to a second base station transmitter. In this method, the same radio channel is used, if possible, before and after the handover for transmitting message information to the mobile station. If the same radio channel can be utilized, the handover takes place without the mobile station being informed beforehand of the handover by a special signal or order or the like. In digital mobile ratio systems with digital transmission of message information by digital modulation of the radio signals, the transmission is preferably started from a second base station transmitter before the transmission is terminated from a first base station transmitter. During a certain transmission time substantially the same message information is transmitted to the mobile station from both the first and second base station transmitters.

230 citations


Patent
20 Sep 1989
TL;DR: In this article, the authors considered the problem of multichannel digital data transmission in buildings and local areas for the configuration of a so-called cordless LAN, where a base station (BS) and mobile user stations (MS) each with a transmitter (S), a receiver (E) for multipath reception and a control unit (ST) are provided in each cell.
Abstract: A base station (BS) and mobile user stations (MS) each with a transmitter (S), a receiver (E) for multipath reception and a control unit (ST) are provided in each cell. Exactly one set of several sequence sets of the auxiliary function used for spectrum spreading is allocated to each cell. Sequences of several sets in pairs have the property that the absolute values of the normalized periodic cross-correlation functions are much smaller than one and for sequences within a set the cross-correlation function in pairs is optimally small around the zero point. Data synchronous generation of the transmission signals takes place in the base station (BS) for all simultaneous connections and the data clock of the received signal is used as data clock of the transmission signal of the user station (MS). Application for digital data transmission in buildings and local areas for the configuration of a so called cordless LAN are considered.

203 citations


Patent
10 Nov 1989
TL;DR: In this paper, a cellular radio system in which a BS1 establishes two way communication with a mobile (10) requests base stations (BS2 to BS7) of a subset of adjacent cells to reserve a channel so that in the event of handover to a base station in one of these cells this can be executed quicker than if the reservation had not been made.
Abstract: A cellular radio system in which a base station (BS1) establishing two way communication with a mobile (10) requests base stations (BS2 to BS7) of a subset of adjacent cells to reserve a channel so that in the event of handover to a base station in one of these cells this can be executed quicker than if the reservation had not been made. In making the request for reservation, the communicating base station (BS1) passes on details of the call-in-progress. Once call has been handed over a new subset of adjacent cells is created.

131 citations


Patent
16 Jun 1989
TL;DR: In this paper, a locating or surveillance system for monitoring the instantaneous position of a mobile object, such as a truck, at a central monitoring or base station is disclosed. But the system is not suitable for mobile objects.
Abstract: There is disclosed a locating or surveillance system for monitoring the instantaneous position of a mobile object, such as a truck, at a central monitoring or base station. The system comprises a receiving system (10, 11) to be located at the central monitoring station, a navigation unit (12) to be located on the mobile oject and operable automatically to determine the position of the object by reference to orbiting navigation satellites or by reference to land based transmissions or receiving beacons, and a radio telephone type transmitter unit (16) to be located on the mobile unit and connected to the navigation unit (12), the transmitter unit being operable to transmit signals which will be received by the receiving system (10, 11) at the central monitoring station and which are indicative of the instantaneous position of the mobile object as determined by the navigation unit (12).

104 citations


Proceedings ArticleDOI
01 May 1989
TL;DR: In this paper, the authors describe a channel assignment scheme for cellular mobile telephone systems in which assignment is based on actual field strength measurements performed dynamically on the functioning system, and a mutual interference criterion is applied to ensure that satisfactory service is maintained throughout the system.
Abstract: The authors describe a channel assignment scheme for cellular mobile telephone systems in which assignment is based on actual field strength measurements performed dynamically on the functioning system. The scheme involves no rigid partitioning of the channel set into geographic patterns, as in conventional systems. A mutual interference criterion is applied to ensure that satisfactory service is maintained throughout the system. The system provides capacity improvements ranging from 100% to 300% depending on the complexity of the implementation. It is implementable using any of the current or proposed modulation schemes. >

93 citations


Patent
03 Nov 1989
TL;DR: In this article, a Viterbi equaliser is used to decode the originally transmitted signal from the two superimposed signals received by the single antenna of the mobile station to achieve diversity without the need for two antennas at the mobile stations.
Abstract: A base station 10 has two transmitting antennas 20, 22 which both transmit the same signal to a mobile station 12, the signal via antenna 22 being delayed by a time delay unit 24 to ensure de-correlation between the transmitted signals. It is unlikely that multi-path fading will occur simultaneously in both signal paths to the single antenna 24 of the mobile station wherein an equaliser 26, such as a Viterbi equaliser, decodes the originally transmitted signal from the two superimposed signals received by antenna 24. Diversity is obtained without the need for two antennas at the mobile station where space limitations would probably prevent this. The base station 10 receives the signal transmitted from the single antenna 24 at the mobile station 12 over two signal paths respectively directed to the two antennas of the base station. The signals received are de-correlated by a time delay 38 connected to one of these antennas and summed, summed 36 and passed to an equaliser 40 for decoding. A repeater station may similarly include time delays (76), (82), (Figs 7, 8), to give de-correlation between the signals it retransmits and the corresponding signals directly transmitted by the base and mobile sections.

79 citations


Patent
Toshimitsu Shimizu1, Yasuhiko Sako1
09 Feb 1989
TL;DR: In this paper, a mobile station in the service zone of a first base station transmits a reconnect request packet to a second base station when leaving the services zone of the first and entering the service zones of the second during a session with the first base stations.
Abstract: In a digital radio communications system, a mobile station in the service zone of a first base station transmits a reconnect request packet to a second base station when leaving the service zone of the first and entering the service zone of the second during a session with the first base station. The second base station communicates the receipt of the reconnect request packet to the central station, from which a proceed-to-clear command packet is sent to the first base station to allow it clear the connection with the mobile station and return a clear response packet to the central station informing it of a serial number of the last data packet it has received from the mobile station immediately before leaving its service zone. On receiving the clear response packet, the central station sends a reconnect command packet indicating that serial number to the second base station to cause it to issue a reconnect response packet to the mobile station requesting the reconnect. The reconnect response packet communicates the serial number of the last packet to the mobile station to allow it to send a copy of data packets which may have been interrupted during the session with the first base station.

76 citations


Patent
Shinichi Miyazaki1
25 Sep 1989
TL;DR: In this article, a mobile station comprises a receiver for receiving a signal from the base station and a transmitter including a frequency synthesizer, a modulator and a power amplifier connected to it.
Abstract: A mobile station comprises a receiver for receiving a signal from the base station and a transmitter including a frequency synthesizer, a modulator and a power amplifier connected to it For power savings purposes, the transmitter is deactivated during a standby mode If an earlier portion of a signal received from the base station indicates a likelihood of a need to return an acknowledgment, power is supplied to the frequency synthesizer to allow it to stabilize in advance If a later portion of the received signal indicates that there actually exists the need to acknowledge the receipt of the signal, the power amplifier is subsequently activated and an acknowledgment signal is returned through it to the base station If the later portion of the received signal indeicates the absence of the need to acknowledge, the frequency synthesizer is again deactivated and the power amplifier remains deactivated

71 citations


Patent
Jan Erik Uddenfeldt1
08 Feb 1989
TL;DR: In this paper, the authors propose a TDMA-based method of transmitting data information in a mobile, cellular, radio communication system operating according to the TDMA principle, such that the bit frequency (f) of the data information is reduced to a new value (fr) in response to the number of unoccupied time slots.
Abstract: Method of transmitting data information in a mobile, cellular, radio communication system operating according to the TDMA principle. Within certain large cells (C2) in the system the number of calls in progress is less than the number of slots (CH1, CH2 . . . ) in each frame, where these slots have been allotted to the mobiles (M1) within the cell. The unoccupied slots thus occuring are utilised in accordance with the method such that the bit frequency (f) of the data information is reduced to a new value (fr) in response to the number of unoccupied time slots. The transmission range between mobile and base station is thus increased.

69 citations


Patent
28 Aug 1989
TL;DR: In this article, a wireless packet communication system is presented, where the transceiver is selected in a pseudorandom manner from a predetermined set of carrier frequencies prior to transmission of each packet or in response to detection of transmission errors.
Abstract: A wireless packet communication system is operable in a frequency band occupied by other transmission sources. The system includes a base station and several remote stations. Each remote station has a transceiver for transmitting and receiving data packets on electromagnetic carriers. The carrier frequency of the transceiver is selected in a pseudorandom manner from a predetermined set of carrier frequencies prior to transmission of each packet or in response to detection of transmission errors. Each carrier frequency may be associated with a unique pseudorandom noise code used to spread spectrum encode packets. The base station has a number of transceivers which operate simultaneously at the different carrier frequencies and which generate different noise codes for spread spectrum encoding and decoding. The base station records data for each remote station identifying the transceiver which last received a data packet and transmits packets addressed to each remote station with the identified transceiver.

Patent
30 May 1989
TL;DR: In this article, a mobile telecommunications system has multiple base stations (10) each defining a miniature service zone (20) and capable of communicating with mobile stations (16) present in the service zone over a radio link.
Abstract: A mobile telecommunications system has multiple base stations (10) each defining a miniature service zone (20) and capable of communicating with mobile stations (16) present in the service zone over a radio link. Geographically associated ones of the base stations (10) are spaced apart from each other by an area in which the mobile stations (16) are not responsive to electromagnetic waves (18) on the radio links, whereby the base stations (10) are allowed to share the same frequency for the electromagnetic waves (18). The base stations (10) are accommodated in an on-road vehicle telecommunications network (22) which switches communications to the base stations (10).

Patent
Koji Tokunaga1
24 Feb 1989
TL;DR: In this article, a mobile subscriber switches a reception frequency during a time period in which no data originating to the given mobile subscriber is transmitted from the base station having a frequency presently used by the mobile subscriber, and tests a reception condition at the switched frequency so as to select an optimal reception frequency.
Abstract: In a method and system in which data is time-divisionally transmitted from a plurality of base stations to a plurality of mobile subscribers at different frequencies corresponding to the base stations, a given mobile subscriber switches a reception frequency during a time period in which no data originating to the given mobile subscriber is transmitted from the base station having a frequency presently used by the given mobile subscriber, and tests a reception condition at the switched frequency so as to select an optimal reception frequency.

Patent
12 Jan 1989
TL;DR: In this article, a hybrid remote control system for extending the range of portable RF transceivers and for providing a select-call system is presented, where a modified full duplex system is used to control transmit and receive cycles from the portable unit so that the system can operate regardless of interference on the channel to which the base station is timed.
Abstract: A method and apparatus for extending the range of portable RF transceivers and for providing a select-call system includes a hybrid remote control system to extend the range of a portable transceiver and to permit the operator of a vessel or vehicle to communicate hands-free through the utilization of his own full power base station and antenna, in which a modified full duplex system is used to control transmit and receive cycles from the portable unit so that the system can operate regardless of interference on the channel to which the base station is timed. Also provided is a selective calling system in which a recipient's transceiver is turned on by the transmitting transceiver through punching in the recipient's call letters or at least its address. As an added feature, the transmitting station automatically transmits its own call letters which are displayed at recipient's receiver. This system thereby quiets all receivers until the particular transceiver is digitally addressed. An emergency code such as (0,0,0,0) activates all receivers for emergency transmissions on an emergency channel, such as on VHF channel 16, so that the emergency channel can be monitored without distraction from non-emergency traffic. This modular approach provides a universal system in which standard transceivers can be accommodated.

Patent
Sasaki Susumu1
25 Jan 1989
TL;DR: In this article, a channel changing system in a mobile unit communication system comprising a plurality of radio base stations making communication with moveable stations through radio channels and a center station for accommodating such base stations and connecting these base stations with the public telephone network is presented.
Abstract: The present invention is a channel changing system in a mobile unit communication system comprising a plurality of radio base stations (3) making communication with moveable stations (7) through radio channels and a center station for accommodating such base stations (3) and connecting these base stations (3) with the public telephone network (6). The center station is configurated comprising a private branch exchanger (1) for accommodating the public telephone network (6) and the lines (4) extending from a plurality of base stations (3) and a controller (2) for controlling changing of communication channels by supervising the signal receiving condition between a moveable station (7) and a plurality of base stations (3). The controller (2) is configurated so that it issues a channel changing command by detecting, based on the signal receiving condition, that a moveable station (7) has transferred to the radio zone of an adjacent base station (3) from the radio zone of a certain base station (3), while the private branch exchanger (1) conducts line changing depending on such command through the extension transfer to the line (4) of adjacent base station (3) from the line (4) to the relevant base station (3).

Patent
04 Oct 1989
TL;DR: In this article, the propagation time for signals to be transmitted between a mobile unit and at least two base stations, thereby obtaining two range measurements, is measured and used in a triangulation process to estimate the position of the mobile unit.
Abstract: A cellular or similar radio system measures the propagation time for signals to be transmitted between a mobile unit and at least two base stations, thereby obtaining two range measurements. This is used in a triangulation process to estimate the position of the mobile unit.

Patent
25 Apr 1989
TL;DR: In this article, a method of reducing blockages and call interruption in handling over calls in a cellular mobile radio system is proposed, where a smaller number of channels are reserved, so-called rescue channels, from the ordinary channels in the system.
Abstract: A method of reducing blockages and call interruption in handling over calls in a cellular mobile radio system. When the signal strength from a base station to a mobile and vice versa falls below a given value the handover shall take place to another base station. In order that the call will not be interrupted, a smaller number of channels are reserved, so-called rescue channels, from the ordinary channels in the system. The rescue channels can be fixed or dynamic for a given base station.

Patent
Aakerberg D1
08 Jun 1989
TL;DR: In this paper, a method of transmitting calls between a radio base station (FS) and one or more portable radio telephones (PS) which are at a short distance from the base station is described.
Abstract: A method of transmitting calls between a radio base station (FS) and one or more portable radio telephones (PS) which are at a short distance from the base station. The base stations of the mobile radio system all have access to all carrier frequencies (f 1 -f 4 ) and transmit/receive call information with the aid of time division multiple access (TDMA). The transmission from a base station (FS) to a radio telephone (PS) occupies time slots (CH1-CH16) within one half of a frame interval and the reception occupies time slots within the other half. When a channel occupies a time slot (CH1) for transmission/reception over a given carrier frequency (f 1 ) the remaining carrier frequencies are blocked for precisely this time slot, and a second time slot with the same (f 1 ) or a second carrier frequency (f 1 -f 4 ) shall be used for a second channel. A radio unit for carrying out the method is described.

Patent
08 Feb 1989
TL;DR: In this article, the authors proposed a method of transmitting message information digitally between mobile and base stations in a cellular digital mobile radio system including base stations (Bm, Bn) and mobile stations (MS1, MS2) with transmitters and receivers.
Abstract: The invention relates to a cellular digital mobile radio system including base stations (Bm, Bn) and mobile stations (MS1, MS2) with transmitters and receivers. The invention also relates to a method of transmitting message information digitally between mobile and base stations in such a system. In accordance with the invention, at least two base station transmitters (Bma, Bmb, Bna, Bnb) at a given transmitting distance from each other are assigned to each of certain cells (Cm, Cn) within a restricted geographical area. The base station transmitters which are assigned to the same cell transmit digitally modulated radio signals within the same frequency range at least partially simultaneously to the mobile stations of the cell. The radio signals from different base station transmitters associated with the same cell are digitally modulated with the same message information to the mobile stations in the cell. Different base station transmitters (9A, 9B) preferably transmit the digitally modulated radio signals with the same message information to a given mobile station with a given mutual transmission time shift. Here, the transmission time shift is selected individually for each mobile station, such that corresponding digitally modulated radio signals with the same message information to a given mobile station from different base station transmitters arrive practically simultaneously at the mobile station.

Patent
Kenzi Aratake1
20 Jun 1989
TL;DR: In this article, a radio data communication system linking a base station and a plurality of terminal stations by radio channels through a control station is presented, where note is taken of the fact that one radio channel can be occupied for only a certain occupied time T and that even after the completion of one data communication the radio channel is held for within a certain holding time t (T>t).
Abstract: An MCA radio data communication system linking a base station and a plurality of terminal stations by radio channels through a control station, wherein note is taken of the facts that one radio channel can be occupied for only a certain occupied time T and that even after the completion of one data communication the radio channel is held for within a certain holding time t (T>t). The present invention allows each of a plurality of terminal stations to share the same radio channels without a channel assignment operation. A communication end signal is simultaneously broadcast upon completion of a first data communication and so that another terminal station demanding a second data communication starts its data communication promptly upon receiving the communication end signal without a channel assignment operation.

Patent
12 Jun 1989
TL;DR: In this paper, a mobile telecommunications system includes a plurality of base stations (10) each being communicatable with a mobile station (16) by radio, and a system center (26) is connected to said telecommunications network (22) for selecting an optimum route on the basis of instantaneous traffic conditions.
Abstract: A mobile telecommunications system includes aplurality of base stations (10) each being communicatable with a mobile station (16) by radio, and a telecommunications network (22) accommodating the plurality of base stations (10) for switching communications to the plurality of base stations (10). A system center (26) is connected to said telecommunications network (22) for selecting an optimum route on the basis of instantaneous traffic conditions. Any of the base stations (10) transmits to the mobile station (16) base station data representative of the base station (10). When the mobile station (16) sends a guidance request for requesting route guidance data, the telecommunications network (22) reports the guidance request to the system center (26). The system center (26) selects, in response to the guidance request, an optimum route matching instantaneous traffic conditions and transmits optimum route data representative of the optimum route to the mobile station (16) over the telecommunications network (22).

Patent
03 Oct 1989
TL;DR: In this paper, a diagnostic test apparatus for a cellular communications system mobile transmitter/receiver unit, which is adapted for direct connection to the aerial connection of an mobile unit (4) of the system whilst installed in a vehicle, was described.
Abstract: Diagnostic test apparatus for a cellular communications system mobile transmitter/receiver unit, which apparatus is adapted for direct connection to the aerial connection of an mobile unit (4) of the system whilst installed in a vehicle, and which is arranged to simulate a land/base station of the system in such manner that when in operation the diagnostics unit appears to the mobile unit as a land/base station of the system. The diagnostic test apparatus includes means for producing any of a plurality of signals and/or functions for simulating corresponding signals and/or functions involved in the system, and means for enabling the application of such simulation signals/functions to the mobile unit (4) to be tested whilst the latter is in situ in its operationally installed condition in such manner as to test the response of the mobile unit to such signals and/or functions.

Patent
10 May 1989
TL;DR: In this paper, the position of the mobile station from a signal transmission time between plural base stations and a specific mobile station is estimated by arranging the base stations so that at least 3 zones are overlapped over nearly entire service area and specifying the reception time from a synchronizing signal in the case of demodulation.
Abstract: PURPOSE:To locate the position of the mobile station from a signal transmission time between plural base stations and a specific mobile station by arranging the base stations so that at least >=3 zones are overlapped over nearly entire service area and specifying the reception time from a synchronizing signal in the case of demodulation. CONSTITUTION:A zone charged by a base station is formed as a circle and the base stations are arranged to form a regular triangle with a distance corresponding to the radius of the circle. When the transmission of the own station number signal is arisen from a mobile station, the signal arrival time information from the relevant mobile station is received from >=3 of base stations. In such a case, a host station selects the three base stations sequentially at the fastest signal arrival time to calculate the difference of the arrival time. Thus, the coordinate obtained as a cross point of two specified hyperbolas is specified as the location of the mobile station. Thus, the host station can recognize in detail at which location of the service area the specific mobile station exists and the position information is used for various incoming control.

Patent
19 Sep 1989
TL;DR: In this article, the authors proposed to control the size of a radio zone by correcting a reception level from a base station with a correction value of the reception level informed from the base station to a mobile station and informing the threshold level of reception level required to make communication from each BS to the mobile station.
Abstract: PURPOSE: To control the size of a radio zone by correcting a reception level from a base station with a correction value of a reception level informed from the base station to a mobile station and informing the threshold level of the reception level required to make communication from each base station to the mobile station. CONSTITUTION: A correction value is informed to a mobile station 4 with an informing signal informed from base stations 1, 2, 3. Moreover, a mobile station 4 reads the correction value with the informing signal from the base stations 1, 2, 3 and measures the reception level 11 of the base stations 1, 2, 3 and obtains the reception level 11 of the base stations 1, 2, 3 and a reception level 12 after the correction to the base stations 1, 2, 3 from the correction value with the calculation. It is regarded by the correction that the radio zones of the base stations 1, 2, 3 are changed automatically. Thus, the size of the zone is controlled by calculating the correction value at the mobile station 4. COPYRIGHT: (C)1991,JPO&Japio

Proceedings ArticleDOI
27 Nov 1989
TL;DR: Simulations and experiments have confirmed that two-branch diversity using the proposed method can provide reliable speech communications using TDMA for a portable radio channel with RMS spread of 555 ns or less and a transmission rate of 450 kb/s.
Abstract: The authors describe and show performance results for a diversity-selection technique in a frequency-selective fading portable radio channel. Diversity selection is performed by using a quality measure obtained from the demodulation process. This technique is compared to diversity selection based on power and diversity selection after channel decoding. It is found that this diversity selection technique is more effective in mitigating selective fading than a conventional technique based on power and that it performs almost as well as diversity selection after channel decoding. This diversity selection technique can be implemented at the portable handset by using only one receiver if the base station transmits in at least one time slot in addition to the communication slot. Thus, its use does not significantly increase the portable's hardware complexity. Simulations and experiments have confirmed that two-branch diversity using the proposed method can provide reliable speech communications using TDMA (time division multiple access) for a portable radio channel with RMS spread of 555 ns or less and a transmission rate of 450 kb/s. >

Patent
17 Oct 1989
TL;DR: In this paper, the authors proposed to eliminate the need for registering a position so long as a mobile equipment is moving in a high in-zone probability area by allowing the mobile equipment to collect the history of the inzone location for a prescribed period.
Abstract: PURPOSE: To eliminate the need for registering a position so long as a mobile equipment is moving in a high in-zone probability area by allowing the mobile equipment to collect the history of the in-zone location for a prescribed period, to make a list of areas with a high in-zone probability for each time based on the effect of learning and introducing an area with the high in-zone probability area of the mobile set. CONSTITUTION: The mobile equipment (Z) 11 recognizes its own in-zone area by receiving a signal sent from each base station and extracting a code specific to each base station. The statistical processing is implemented to the in-zone area every time obtained in such a manner and a list is prepared in which area names are arranged in the order of higher in-zone probability. The prepared list is informed to an exchange station (F) 12, which stores the list to a memory. When it is discriminated that the mobile equipment (Z) 11 exists in the high in-zone probability area while the mobile equipment (Z) 11 receives a control signal from a base station and detects a code inherent in the base station, no position registration is needed. COPYRIGHT: (C)1991,JPO&Japio

Patent
27 Nov 1989
TL;DR: In this article, each mobile radio-telephone 4 has a unique identification code and responds to reception of a signal broadcast on a unidirectional link which contains the identification code thereof by transmitting a signal on a bidirectional communications link.
Abstract: Each mobile radio-telephone 4 has a unique identification code and responds to reception of a signal broadcast on a unidirectional link which contains the identification code thereof by transmitting a signal on a bidirectional communications link. If the mobile radio-telephone is within range of base station 5, then the latter responds on the bidirectional link establishes a communications channel between the mobile unit and the caller. If the mobile radio- telephone is not within range of a base station it will not receive a response and, after a predetermined time with no response, it may store information on the call-in attempt, or indicate to the user that an unsuccessful attempt has been made. This avoids the need to continuously track mobile radio-telephones. The unidirectional link may be a television or radio broadcast network, or a communications satellite.

K.J. Bye1
11 Dec 1989
TL;DR: In this article, a computer simulation tool has been developed to quantitatively compare handover algorithms in a system design; hence, a simulation tool was developed to expedite this comparison.
Abstract: Cellular system operation relies on frequency reuse, with cell sizes and reuse distances governed by receiver tolerance to cochannel interference. It is possible for a mobile unit to move away from the initial base station during communication, so the facility to handover the link to adjacent base stations is a necessary feature of the network. The complexity of the problem renders it difficult to quantitatively compare handover algorithms in a system design; hence a computer simulation tool has been developed to expedite this comparison. This has been used for handover criteria performance assessment within the model. A first order estimate of typical signalling loads anticipated in microcell based systems has been obtained. Simulation illustrates the excessive handover numbers compared with the number of cell boundary crossings, whenever the criteria chosen exhibit statistically indeterminate behaviour. However, the performance can approach that of a deterministically controlled system if the handover algorithm is modified. More sophisticated handover algorithms could magnify this effect.

Patent
27 Dec 1989
TL;DR: In this article, a mobile station 5 uses the intensity of electric field, BER (bit error rate) of data, or the like to measure the reception quality of each control channel and select the best base station.
Abstract: PURPOSE:To always communicate with an optimum base station by using the property of TDMA(time division multiple access system) and successively scanning control channel signals of a base station being in service and peripheral base stations by a mobile station to measure reception qualities and selecting an optimum base station. CONSTITUTION:With respect to a mobile station 5, one of n-number of time slots is set to the communication state, and the other time slots are in waiting or stop states. Consequently, the mobile station 5 scans control channels of respective base stations during the waiting or stop state though performing communication. The mobile station 5 uses the intensity of electric field, BER(bit error rate) of data, or the like to measure the reception quality of each control channel and selects the best base station.

Patent
16 Oct 1989
TL;DR: In this paper, a radio telephone switching control system having control channels which transmit/receive control data with respect to a plurality of movable terminals and a radio base station is described.
Abstract: A radio telephone switching control system having control channels which transmit/receive control data betweeen a plurality of movable terminals and a radio base station. The control channels include a mono-functional channel for access which is dedicated to access during data transmission/receiving by calling from the terminals. The control channel also includes a bi-functional channel for paging and access usable as a channel for paging one of the terminals as well as for access. The system contains a base station with a fault detector. Only one kind of control channel information is broadcast in the same service zone. All of the movable stations existing in same service zone scan the first or second range to decide the channel for access or paging according to the received control channel information. The system also sets the mono-functional channel for access and the bi-functional channel for paging and access, when a fault is not detected. Once a fault is detected, the second range is separated from the first range, whereby the mono-functional channel for paging is used only to transmit data for paging from the base station and the mono-functional channel for access is used to transmit/receive data related to actions other than paging to the terminals.