Showing papers on "Base station published in 1978"

Spread spectrum apparatus for cellular mobile communication systems

Abstract: An apparatus is disclosed for a cellular mobile communication system utilizing a spread spectrum. A plurality of fixed base stations is connected with a central processor so that calls originating in any cell can terminate in any other cell. The available frequency spectrum is divided such that one-half is used for mobile-to-base station transmission and the other one-half is used for base station-to-mobile unit transmission. A power control/mobile locator system and method is utilized in all mobile units to compensate for changes in signal level and to maintain the average received signal level at the base station constant regardless of the location of the mobile unit within the cell. In addition, each mobile unit has a unique set of time-frequency coded waveforms that are used for both transmission and reception. The waveforms have large time-bandwidth products so that interfering signals are well suppressed, and which provide a large set of signals so that each user can be assigned a unique set of waveforms. Message modulation is accomplished by digitizing the speech and encoding the resulting binary sequences into the set of waveforms available to the user, while detection is accomplished by a demodulation system and method in which the phases of each received waveform are compared with those of the preceding waveform.

Synchronizing means for a two-way communication system

Abstract: Digitally encoded data is carried over a first channel between a base station and a plurality of mobiles with the mobiles sharing a second channel for transmission to the base on a contention basis. Proper decoding of the data requires clock syncing at the receiver site. To hasten clock recovery lock time at the base station and improve system throughput, each mobile includes apparatus for monitoring transmissions by the base station and deriving a transmit clock base for the mobile's transmitter therefrom such that subsequent transmissions by the mobiles are all substantially in synchronization.

Method of signal transmission and reception utilizing wideband signals

Abstract: A method is disclosed for signal transmission and reception utilizing wideband signals, and, more particularly, the use of time-frequency coded signals to achieve more efficient use of the electromagnetic spectrum. The method can be generally utilized for signal transmission and reception, including personal communication uses such as utilized for land-mobile radio communications. Each user is assigned a unique set of time-frequency coded waveforms for both transmission and reception, and both message and control signals are transmitted and received using the assigned unique set of signals. Message modulation is effected by digitizing the message, such as a speech message, and several types of message digitization, including PCM are set forth. For land-mobile radio service, the geographical area is divided into a series of cells each of which has a base station therein for communication with the mobile units then in the cell. Each mobile unit transmitter utilizes automatic power control to maintain the received signal level at the base station constant regardless of the location of the mobile unit within the cell.

Transmitter multiplexing system for a land mobile communication system

Abstract: A common transmitting antenna system for a base station in a land mobile communication system like a land mobile telephone system consists of an antenna system with a plurality of input terminals which are so arranged as to avoid mutual radio signal interference, a plurality of transmitter multiplexers comprising a plurality of bandpass filters and a junction box for combining outputs of the bandpass filters, the output terminal of which is connected to one of the input terminals of the antenna system, and a plurality of transmitter groups respectively connected to the output of the bandpass filters. The pass bandwidth of the bandpass filters in the transmitter multiplexers are so selected that when they are arranged in the order of their pass bandwidth, the entire land mobile communication system frequency bandwidth assigned to the base station transmission may be covered by these pass bands. The transmitter groups feature automatic frequency tuning of multiradio channel capable of transmitting entire radio channels in the pass bands of the band pass filters in the transmitter multiplexer. Thus, a land mobile communication system is provided wherein the transmission channels may be instantaneously switched.

Base station feedback reporting system

Abstract: The operational status of equipment located at a base station is reported to a remote control terminal. The same audio channel that is used for sending audio signals and control signals to the base station is also used to carry the report signal. The control signals to the base station and the report signals from the base station are encoded tone burst signals. The report signal provides an indication of the proper receipt and execution of a control signal by the base station equipment. Equipment diagnostic signal and periodic checks of equipment performance are also reported by this system.

800-MHz band land mobile telephone system—Overall view

Abstract: The 800-MHz band land mobile telephone system which is going into service in Tokyo and other major cities is described. This system is characterized by 1) an ordered array of cells which allows each radio channel to be reused by spacing at an appropriate coordination distance in a wide service area (cellular system), 2) development of a new higher frequency band, and 3) a fully automatic exchange system integrated with the ordinary telephone network. Field tests have been carried out in the Tokyo metropolitan area since 1975 and have now been brought to a successful completion.

Radio transmission systems

Abstract: A radio transmission system is disclosed having a base station with a plurality of spaced radio transmitters in which an information signal is simultaneously transmitted on the same carrier frequency channel from all the transmitters. Each information signal is transmitted at least twice while the relative transmission powers of the transmitters are varied between one transmission of an information signal and a subsequent retransmission of the same information signal.

Multitransmitter digital signaling system

Abstract: In a multitransmitter digital signaling system for mobile communications consisting of a plurality of base stations, different waves are superposed on the digital information signals in adjacent base stations and carrier waves of the same frequency are angularly modulated by the superposed signals at the same modulation index and simultaneously transmitted from the base stations to one service area.

Mobile radiotelephone unit

Abstract: PURPOSE:To make the abbrebiation dialing service from a mobile terminal station possible by providing a memory function of dial signals and the reproducing function in the base station side. CONSTITUTION:Radio base station 2 is provided with RAM29, which is a memory function of dial signals, and a reproducing function. Switch 13 is operated and write signals are transmitted to store previously dial signals, which the operator wants to store, into RAM29 of the base station from mobile terminal station 3. Switch 16 is operated to transmit read signals and set a transmission read state as required. Next, regular dial numbers stored in RAM29 are read out on a basis of abbrebiated dialing and are transmitted to the exchange side. As a result, a connection reliability can be improved because required dial signals are stored under a stable state previously and abbrebiated dialing is used as required.

Trace telephone system

Abstract: PURPOSE:To facilitate the connection from the exchange to the mobile radio terminal by receiving the area signal from the base station within each area through the mobile terminal and then transmitting the signal including the self-terminal number every time the terminal changes its belonging area. CONSTITUTION:Base station 4 and 5 of area A and B transmit the area identification signal every fixed time, and mobile radio terminal 6 receives the area identification signal from the base station in the area of its own. When terminal 6 moves to area A from other area, it detects the variation of the area identification signal to be received to transmit the signal including the self-terminal number to station 4. Station 4 transmits the signal to exchange 1 via circuit 7, and exchange 1 memorizes the storage position information of circuit 7 of the memory corresponding to the terminal. When the incoming call is produced at terminal 6, exchange 1 calls out nearest telephone 2 of terminal 6 based on the contents of the memory to secure the talking with the owner of terminal 6.

Wireless station locator

Abstract: PURPOSE:In the wireless system having a great number of mobile wireless stations, positions of these mobile wireless stations can be determined automatically without using special equipment and facilities but by providing a very simple adapter for the base station

Medium frequency mine communications

Abstract: Wireless radio transmission at Medium Frequency (MF) is feasible for both personnel and vehicular communications in underground mines. MF radio does not suffer from the severe corner losses and leaky feeder installation requirements of Ultra High Frequency (UHF) radio. Propagation data obtained in both coal and metal/nonmetal mines has encouraged several organizations to develop portable and base station equipment.

Channel geover system of busy channel i n mobile communication

Abstract: PURPOSE:To prevent the outgoing of noise at the time of changing the channel, by turning off the gate of the talking circuit from the mobile station to the direction of the base station.

Spectrum Efficiency for Multiple Independent Spread-spectrum Land Mobile Radio Systems

Abstract: The use of spread-spectrum modulation in a common type of land-mobile radio service is studied. The radio service contains many networks operated independently, similar to the business land-mobile radio service. Network independence implies (among other things) that there is no central control of a transmitter's radiated power. A congested urban environment is assumed. If a band is allocated exclusively to spread-spectrum modulation for such a service, base stations and mobiles must operate on different channels, and all base station antennas must be located within a relatively small area. In this case, the worst interference is in the mobile-to-base channel. An explicit formulation of the "far-near" problem and a powerful computer calculation both show that in such a service spread-spectrum modulation is less spectrum efficient than conventional FM modulation. In fact, the spectrum efficiency of the spread-spectrum systems is inversely proportional to the cube root of the processing gain. However, overlaying a spreadspectrum system on conventional bands shows some promise.

Busy channel switching system

Abstract: PURPOSE:To simplify the process at the monitor station and to ensure an assured switching for the busy channel by making the moving object select and catch the signal featuring an intensive receiving intensity among the signals transmitted from plural base stations in the mobile transmission system.

Mobile radio control system

Abstract: PURPOSE:To decrease undesired process at a control station and to improve the quality of service for the connecting time, etc., by adding the idle channel information to a control signal and transmitting them at a base station having no idle channel. CONSTITUTION:A service area 1 is formed with plural minor line zones 2 which are sufficiently capable of transmission with the transmission power of a mobile station. A base station 3 is provided for each zone 2, and at the same time a general control station 4 is set for the area 1 as a whole. The station 4 uses the common control channel of each zone 2 to perform the transfer of the control signal to the mobile station and controls the mobile station. Then the station 3 relays the control signal 9 to the station 4 together with the idle channel information 10. At the same time, the station 4 performs a control so as not to select the station 3 having no idle channel when the zone 2 where the mobile station is located.

Connection control system for radio call channel

Abstract: PURPOSE:To realize an economical system for a shifting communication using a base station control unit and connecting a shifter unit which is grouped within a switchable range of the radio call channel.

Test system of mobile communication equipment

Abstract: PURPOSE:To make it possible to make an operation test of communication facilities of the mobile station from the base station, by automatically responding to the signal from the base station from the mobile station.

Call control system for mobile radio

Abstract: PURPOSE:To reduce the ineffective usage of channels and to increase the number of mobile sets which can be accommodated, by the instruction of the retransmission stop of the call signal to all other base stations from the control station, when the answering signal from the called mobile set is received in a base station.

Position detecting system for mobile radio station

Abstract: PURPOSE:To eliminate the installation of the fixed transmitting and receiving stations by giving a position detecting function only to the base station, and thus to promote the economization of the facilities.

Land mobile radio system performance model for VHF and higher frequencies over irregular terrain

Abstract: A model is described which may be used to predict land mobile radio system performance over irregular terrain. The model uses a semi-empirical formulation to calculate propagation losses from a selected base-station location to surrounding mobile locations within a variable-size "box" not exceeding two degrees latitude by two degrees longitude. Terrain data is obtained from a computer-accessible data base. The output is a plot showing contours of constant propagation loss, power density, or available received power.

Circuit control of mobile communication

Abstract: PURPOSE:The time in which the noise is existing between a base station and a mobile station is shortened, thereby reducing the discomfort to the subscriber at a mobile station side.

Dial signal transmission system

Abstract: PURPOSE:To prevent a misconnection resulting from the circuit deterioration and to securs an application of the touch tone dial system for a mobile radio circuit, by opening the radio circuit of the mobile station side in case the signal is received with incorrect intervals at the base station

Detecting system of mobile radio congestion

Abstract: PURPOSE:To take a suitable transmission controlling step, by measuring at the base station the working factor of the channel by the transmission of the mobile apparatus, and detecting the congested condition.

Technical Tradeoffs for Spectrum Efficiency in a Personal Radio Service

Abstract: Citizen's Band (CB) radio channels are already badly congested in large metropolitan areas, and the number of licensed sets is increasing several million per year. In addition, interference from skywave propagated CB signals during the three years near the peak of the next solar cycle (two to four years from now) will probably significantly decrease the opera­ tional range of users in less congested parts of the country. 1 ' 2 As a result, the Federal Communications Commission (FCC) has been studying the possibility of establishing a new Personal Radio Service to supplement the Citizen's Band service.

General commanding communication system

Abstract: PURPOSE:To make it possible to give a general command rapidly improving the efficiency in use of a radio channel, by transmitting a specific signal from the base station to any channel on communication for maintenance.

Digital pulsed DC remote-control system

Abstract: A remote control system and method therefor is disclosed that includes a control station coupled by a two-wire line to a base station having a transmitter for providing simplex radio communications to mobile radios. The control station utilizes digital pulsed DC signalling to select a radio channel of the base-station transmitter for transmission of each message. In response to activation of a transmission switch, the control station applies a DC voltage to the two-wire line and thereafter applies a command pulse train having a predetermined number of pulses corresponding to the selected radio channel. The base station is responsive to the DC voltage on the two-wire line for receiving the command pulse train. The pulses in the received command pulse train are totalized, and the base station transmits the message on the radio channel corresponding to the totalized number of pulses.

Mobile-station general calling system

Abstract: PURPOSE:To enable a base station to confirm the response state of each mobile station in a short time without making each mobile station perform different time setting, by effectively using radio channels. CONSTITUTION:Mobile stations Ml to Mm, which are equipped with their own transmitter-receiver and share radio channels (fl) to(fn), use free channels by changing them. Base station B, on the other hand, is provided with control board 1 and required unit 2. Once a general call is made by base station B, one specific free radio channel is assigned and a channel fixing signal is sent out. Simultaneously, a free channel for response signal transmission at the side of mobile station M is found and another free-line signal different from the above-mentioned signal is sent out. On receiving this signal, mobile station M stops changing over radio channels corresponding to it and detects a general calling signal from the base station, so that while a general calling tone is sent out from a speaker, etc., switching operation of radio channels will be restarted.

Countermeasure system for trouble o f mobile radio

Abstract: PURPOSE:To prevent the trouble of the transmission line from giving the influence to the whole service ares, by installing the trouble detector in each base station, and discontinuing the radiation of the wave of the transmitter in trouble time of the transmission line from the control station.

General command communication system

Abstract: PURPOSE:To make all radio stations wait for the corresponding radio circuit by switching the antenna signal which is sent to a radio station from the base station via a radio circuit into the corresponding code at the general command sending time.