Showing papers on "Base station published in 1979"

The effect of fading and shadowing on channel reuse in mobile radio

Abstract: Co-channel interference probabilities are calculated for mobile radio systems operating in a Rayleigh fading lognormal shadowing environment with inverse fourth power law dependence of area mean signal level on range. Interference levels are shown to be high even with generous reuse distances. The results are used to calculate spectrum utilization using reasonable but tentative estimates of protection ratio and channel spacing for SSB systems. On this basis SSB offers a higher spectral efficiency than current 25 kHz spaced FM systems.

Mobile telephone channel exchange system

Abstract: A mobile telephone communication system is provided with a plurality of mobile units having a transmitter-receiver capable of being tuned to a plurality of radio channels. A plurality of base stations are provided with receivers capable of detecting carrier level drop-off and a control station is operable to command the given base station to transmit an instruction to the mobile unit commanding it to transmit its signal over a channel which is common to all of the base stations. The control station is then operable to detect an increased carrier level in a zone corresponding to a second base station, and to instruct each of the base stations to transmit a signal over the common channel commanding the mobile unit to switch channels to an idle channel corresponding to a second base station.

Radio channel control systems of mobile radio telephone systems

Abstract: The service area of the radio telephone system is divided into a plurality of radio zones and a base station is installed in each radio zone. The base station is connected to a control unit through a common control channel and a plurality of speech channels, the control unit is connected to an ordinary telephone network, and the control unit is controlled by first and second sequence controllers for the radio system and an exchange control unit, respectively. In a modification, each first and second sequence controller comprises a plurality of discrete sequence controllers classified according to their functions.

Cellular land-mobile radio: Why spread spectrum?

Abstract: It is widely recognized that the electromagnetic spectrum is a beleaguered resource, and nowhere is this more evident than in the land-mobile radio service. The existing allocations of spectrum have long been oversubscribed in many major cities, and huge backlogs of potential users with no allocations have built up in many areas. Cellular land-mobile radio systems are widely recognized to provide a potential solution to this problem, and cellular systems using conventional analog modulation techniques have been proposed [l], [2]. This article discusses the authors' belief that spreadspectrum can substantially improve the spectral efficiency of a cellular land-mobile radio system, as well as making it more versatile and better adapted to the environment. It should be emphasized, however, that the theoretical work on which this belief is based is in a very preliminary stage and that much more study and simulation, as well as a field trial, are required before the validity of the claims made here can be established. Indeed, much of the work described here is controversial and, hence, a major function of this paper is to present these views to a wider audience and thereby encourage further discussion of them.

Mobile radio space diversity system using optical fiber

Abstract: PURPOSE:To make space diversity of the mobile radio system possible by constituting the transmission line between plural base stations and line control base stations by optical fibers and by modulating the light by the carrier frequency or the intermediate frequency and transmitting the light CONSTITUTION:The signal from antenna 13 of mobile station 11 is acquired by antennas of radio base station 12a and line control radio base station 12b The signal acquired by base station 12a is amplified in 14 and is subjected to frequency conversion in 15 and becomes an intermediate frequency signal and is sent to light modulator 16 Light modulator 16 modulates the light by the sent signal and transmits the light signal to base station 12b through optical fiber transmission line 17 Base station 12b demodulates the signal from transmission line 17 by light demodulator 18 into an intermediate frequency signal, and this signal and the intermediate signal, which is acquired from the antenna and is subjected to frequency conversion in 15, are synthesized with the same phase by synthesizing circuit 19 The signal synthesized by circuit 19 is demodulated in 20 and is sent to sound circuit 21 Since receiving signals from respective base stations are synthesized in the intermediate frequency band with the same phase, frequency of level lowering dependent upon fading is reduced

Mobile message communication system

Abstract: PURPOSE:To utilize a frequency effectively by making it possible to use the same frequency for communication by performing message communication between the base station and a mobile terminal under the control of the base station. CONSTITUTION:The base station stores temporarily messages from general subscribers in memory 3 of the base station. Memory contents are read by the control of control part 8 and are transmitted through transmission/receiving switching part 12. The mobile equipment receives the signal from the base station to transmit a response signal, and reads and transmits messages, which are stored in memory 22 previously, to the base station when the calling permission signal is received from the base station. Thus, message communication is performed under the control of the base station, so that the same frequency can be used for communication.

Polling time slot system

Abstract: PURPOSE:To enable to deliver the emergency signal to the base station with minimum transmission wait, by providing the time slot to deliver the emergency signal between time slots. CONSTITUTION:The times T1' to Tn' are specifically determined for each mobile station 2, and the time of timer 6 is set to each mobile station 2 so that the specific time slots t1' to tn' assigned respectively can be formed. Further, the time slots t1' to tn' are formed by clipping the time slot to so that the base station can receive the emergency signal FE. Further, emergency happens between the time slots t1' at the mobile station 2, then the mobile station 2 transmits the emergency signal FE through the radio set 8 from the emergency communication controller 10. The base station 1 receives the emergancy signal FE at the time slot to and the emergency communication controller 11 recognizes the emergency. Further, if it is necessary to confirm the mobile station 2, the specific number is also included.

Land mobile communications and position fixing using satellites

Abstract: In a recent series of experiments, the General Electric Corporate Research and Development Center demonstrated effective satellite-aided land mobile communications, analog and digital data relay, and automatic real-time vehicle position fixing. In one sequence of tests a station wagon was equipped with a specially designed antenna, a slightly modified commercial VHF transceiver, and a digital tone-code ranging responder that operated within the communications bandwidth. The General Electric Radio-Optical Observatory near Schenectady, NY, was the major earth terminal. A commercial VHF base station with a satellite antenna deployed first in an office building in Washington, DC, and later in Tucson, AZ, represented a headquarters or a sector office ground station. Communications were relayed by NASA's ATS-3 geosynchronous satellite. Both ATS-1 and ATS-3 were used for position fixing the vehicle. Voice, slow scan television, audio test tones, prerecorded intrusion sensor data, and telephone patches were relayed by the satellite to and from the vehicle under a variety of conditions in greater Washington, DC, and in the southwestern United States. The experiment demonstrated continent-wide communication of a quality comparable to fringe area reception of present local VHF mobile communications but with a notable lack of multipath flutter. Due to the high angle of signalling path from the vehicle to the satellite, solid structures such as buildings, mountains, bridges, or tunnels degraded communications only occasionally. An absolutely clear line-of-sight signalling path was not required. Trees directly in the signal path seldom interrupted communications. Noisy radio environments such as power lines and vehicle ignitions degraded signals received in the vehicle but did not affect vehicle transmissions. Vehicle positions to within one quarter mile were achieved in real time and within several hundred feet after post experiment recalibration and analysis. In another sequence of tests, similar equipments plus biomedical sensors and a medical telemetry unit were installed in an ambulance. NASA's ATS-3 satellite relayed two-way voice communications between a hospital and the ambulance and electrocardiograms from the ambulance to the hospital. Signals were received with excellent quality from various points within the United States, all well beyond the range of conventional line-of-sight communications. The future of operational systems depends not only on technology but on the need to define user requirements, international frequency allocations, and a commitment to support the initial hardware investment. One key technology that would have to be developed is a multibeam spaceborne antenna with low sidelobes. It has yet to be shown that a large space structure will be low enough in cost to attract the large number of subscribers needed to make it an attractive business venture. It appears likely, but not certain, that the cost of a satellite system to serve large, thinly populated areas may be less than a network of terrestrial repeaters that serve the same area. The likelihood is sufficient to justify further studies.

Mobile message communication system

Abstract: PURPOSE:To increase the frequency efficiency and then realizing the large capacity as well as the econmization, by carrying out the message transmission between the mobile station and the telephone of the telephone subscriber which is connected to the mobile message exchange. CONSTITUTION:The communication system comprises telephone set 1, general exchange 2, mobile message exchange 3, mobile message exchange 3, mobile message control station 4, mobile message base station 6, mobile station 8 and others. And in case the message is transmitted from telephone 1 to station 8, station 4 accepts the dial from telephone 1 with reply of ''This is the mobile message service center.'' via the talkie. Then the numbers are memorized for both the originating and incoming subscribers. After this, the calling subscriber 1 supplies the message in voice and within the time given. This message is also memorized at station 4. Thus station 4 gives the storage conversion to many stored data and then transmits them to station 8 in sequence, and station 8 sends the incoming reply signal back to station 4 with the information of ''The message has assuredly been transmitted.'' given to the originating subscriber. Thus the message transmission completes.

Leaky feeder radio techniques for mines and tunnels

Abstract: Leaky feeder systems should include frequently spaced in-line repeaters for consistent performance and to minimize line and mobile transmitter powers. In the well-established "daisy chain" arrangement of a parallel telephone line is now obviated by a return path through the repeaters at audio or medium radio frequency. The BDR (bi-directional routing) system is also in very successful operational service and an improved version is under trial. Such systems lend themselves to unique diversity arrangements for overcoming multipath effects in tunnels. The use of repeaters rather than multiple base stations is particularly economic in multi-channel operation.

Control signal relay system for mobile communication

Abstract: PURPOSE:To make dependent the subradio base station, without increasing control lines, by selecting the signal with maximum reception level among the subradio base stations and the radio base station and transmitting the signal to the radio channel control station. CONSTITUTION:The control signal received at receivers 23, 24 is added with the reception level information and transmitted to the radio base station. The radio base station compares the reception level at a receiver 28 of the station with each reception level transmitted from subradio base stations 11, 12, to select the radio base station or the subradio base stations having the maximum reception level, and the level information selected is added at the end of the digital control signal and the resultant is delivered to a radio channel control station 11.

Informing system for mobile station position of mobile radio communication

Abstract: PURPOSE:To enable the base station to know existance of the mobile station at a certain radio zone by adding the proper number to the position informing signal through the mobile station. CONSTITUTION:In case the mobile station exists in radio zone B and the power source is made, it is supposed that the waves of the channels receivable at the mobile station are sent to transmitter 1a, 1b and 1c of the base station in that order. Here when transmitter 1a has transmission, the mobile station cannot receive the wave since it is in zone B but can receive the wave radiated next from transmitter 1b. Then the mobile station transmits the position informing signal. In this case, the mobile station's proper number is added to the signal, and as a result the existence of the mobile station at a certain radio zone can be known at the base station.

Capacity degradation of packet radio fading channels

Abstract: A mathematical model is developed to determine the probability of successful transmission of a packet over a fading land mobile data channel.The model is further extended to packet radio channels and the throughput degradation of three random access schemes is analyzed. A relationship between throughput degradation and distance from the base station is finally derived and numerical results presented.

Confirmation system of line selection for mobile radio equipment

Abstract: PURPOSE:To increase the reliability about the confirmation of line selection, by making common the function of confirmation for the line selection in outgoing and incoming call of mobile radio. CONSTITUTION:Collation signal which displays the mobile radio equipment number of itself is provided with the mobile radio unit 15 and the collation signal confirming unit 11 is provided with the base station, which received the collation signal and collates the presence of coincidence with the mobile radio unit number desired. Further, the collation signal confirming unit 11 performs the confirmation of selection to either of incoming or outgoing of the mobile radio unit 15 via the communication radio line transmission and reception unit 12, when selection is made from the mobile radio unit 15 to the communication line designated every occasion via the controlling radio line transmission and reception unit 14 of the base station. Thus, the reliability as to the confirmation of line selection can be increased.

Synchronization control system for terminal station

Abstract: PURPOSE:To make possible the data transmisstion even when the reception field is fluctuating and thus to enhance the reliability for the mobile radio system by providing the local allotment time counting function to the mobile station. CONSTITUTION:When one of plural units of start pulses added with the sequential number given from the base station is received in a correct way, counter 15 is started. And the allotment time of the own station is counted based on the sequential number to carry out the data transmission within the allotted time. In case the next start signal cannot be received from the base station, the data is transmitted repetitivery with every system cycle time from the data tranmsission time based on the counting of the system cycle time via system timer 17. After this, counter 15 and timer 17 are reset when the start pulse is received correctly. Thus, the local allotment time is counted again.

Adjusting method for interrstation delay phase amount

Abstract: PURPOSE:To eliminate the effect caused by the uneven delay phase amount between the transmitter and the receiver of the repeater station by giving the preliminary adjustment of the delay phase amount between the master station and the slave station in the method with which the data signal delay phase amount is made constant between the base stations by means of the radio system. CONSTITUTION:Master station 20 contains 1st transmitter and receiver 2 and 3 of the radio system plus phase difference measurement unit 1 connected to 1st and 2nd variable delay circuit 4 and 12; 2nd slave station 21 includes 2nd transmitter and receiver 10 and 11, demodulator 8 and 2nd transmitter 9; and 1st slave station 22 contains demodulator 16 plus 3rd transmitter 17 and 18 respectively. A connection is given betwen 2 and 11 as well as between 3 and 10 via the wired circuit, and the radio wave is repeated between station 20 and 22 via station 21. In such system, the delay phase amount is measured by unit 1 during the time the wave transmitted from transmitter 2 is received at receiver 3. And the delay phase amount is adjusted via delay circuit 5 and 13 and then applied to demodulator 8 and 16 of station 21 and 22 via the wire to perform an adjustment of the phase amount.

Simultaneous multioffice diversity reception system

Abstract: PURPOSE:To simplify the constitution of a base station, and to improve an error ratio by exercising composition in a central station by controlling the level of the detection output in proportion to the center value of the envelope of a carrier in each base station on mobile communication

Radio telephone set

Abstract: PURPOSE:To attain excellent-S/N transmission with a little amount of signal klirr- attenuation by enabling a base station to detect a push-button dial signal from a mobile station or to read a digital coded signal from the mobile station before transmitting it to a switchboard side. CONSTITUTION:A push-button dial signal from a mobile station is received by receiver 2 of a base station, and frequencies F1, F2 F4 from push-buttom dial signals are detected by detection circuits 31 34 and outputted from oscillation circuits 41 44 to the switchboard side by being mixed 5. Further, digital coded signals, generated coding circuit 14 and transmitted 15 from mobile station 11, are recieved 72 at base station 70, where codes are read 73 to make oscillations 61 64 via timing circuits 51 54, so that signals will be transmitted from synthesizer circuit 74 to the switchboard side. Consequently, signals can be transmitted from the mobile station to the switchedboard side at an excellent S/N ratio with a little amount of klirr-attenuation.

Automatic set point detection system

Abstract: PURPOSE:To accomplish automatic detection of set points by means of an emergency receiver jointly used as a ground detection receiver eliminating elements on the ground and cars. CONSTITUTION:An input signal is transmitted to a base station on the ground through a transmitting antenna 21 from a mobile station on a car in detection of the zone (receiving zone) of the base station set along the rail tracks. Here, an automatic channel scanning circuit 23 is provided to serve as an emergency receiver. Channels f1 - fe are scanned with an automatic channel scanning switch 22 and the electric field of the channels is discriminated with a field detector 24. Thus, the best channel is outputted to control circuits 15, 16 and 17.

Control system for mobile communication line

Abstract: PURPOSE:To simplify the base station euqipment, by using the communication channel in vacant condition to the transmission and reception of the line control signal at mobile set outgoing without providing the oscillation control channel of the base station, in the mobile communication line control system at the area less in mobile subscribers. CONSTITUTION:In the mobile communication line controller 12s in which the incoming control channel and a plurality of communication channels are assigned to each base station and the transceivers PTX, RTX for each channel and those VTX1 to VTXk and VRX1 to VRXk for the communication channel are provided, the vacant channel detection and number information generating circuit 23, selector circuits 231 to 23k, vacant line control circuits 241 to 24k, vacant memory 18 and the communication channel set control circuits 171 to 17k are provided. Further, the line control for the incoming of the mobile subscriber is made by using the control channel exclusive use for incoming, and the line control at outgoing from the mobile subscriber is made by transmitting and receiving the control signal via the communication channel in vacant condition.

Mobile communication controlling method

Abstract: PURPOSE:To prevent a mobile station from taking a specific word or a noise for a normal control signal from a base station, by discriminating the regularity of the fixed code of the control signal. CONSTITUTION:On receiving start code 11 in channel swtiching command signal 10 transmitted from the base station, the mobile facility in a call state discriminates whether it is a start code or not. When it is identified as the start signal, the regualrity of the split phase signal of signal-kind discriminative code 12 is discriminated. Then, when it is discriminated that it has the regularity, a channel is disconnected and the mobile facility receives channel assignment code 13 and switches the its own channels according to the assignment channel. When it is discriminated the split phase signal is irregular, on the other hand, it is not regarded as the channel switching command signal and the channel is not changed over, thereby maintaining the channel state.

Position detection method for digital mobile communication

Abstract: PURPOSE:To constitute the system hardly subjected to the effect of various errors, by obtaining the effect equivallent to the electric field strength measurement digitally, through the utilization of the diagnostic series produced with the decoder for the error correction code in the basic station reception unit. CONSTITUTION:Assuming that the mobile body M is in running in frequency f1 at the zone A. The electric field is lowered, which is received at the base station A at the end of zone, and since the code error of the delivery path is increased, the counted number of ''1'' of the measurement 213 for diagnosis series is increased. If this counted value exceeds a criterion, the control station S makes instruction to the peripheral base stations B and C and lets the electromagnetic waves in frequency f1 to receive with the position detection receiver. Further, the control station S compares the average count number of ''1'' of the measurement 219. For example, if the counted number of ''1'' at the base station B is minimized, the mobile body M can be judged that it is transferred from the zone A to B.

Zone discrimination system of mobile radio communication

Abstract: PURPOSE:To make it secure to discriminate zones by discriminating zones in dependence on only free-line pilot signals assigned to base stations. CONSTITUTION:Base stations (a)-(d) transmit free-line pilot signals I-IV, assigned to base stations differing from those of adjacent stations, through free radio channels. Mobile station X detects a specific free-line pilot signal by sequentially changing over radio channels 4, at least one of them agrees with all base stations. When the free-line pilot signal is detected, the switching of radio channels is stopped; when the current S/N ratio is greater than a prescribed value, position registration is made to hold the channel in readiness and when less, the switching is restarted. After all channels are changed over once, the detecting circuit is changed over to detect another free-line pilot signal.

Mobile subscriber calling system

Abstract: PURPOSE:To make communication possible even when a mobile subscriber is away from a car, by adding a detachable, miniature, lightweight call-signal receiver to the mobile station unit of a car telephone set and by carrying the receiver with the subscriber who is away from the car. CONSTITUTION:When getting off the car, the mobile subscriber extracts call-signal receiver 4 from the container case, which is detected attachment-detachment detecting circuit 16 to close electric power switch 15 of receiver 4 through the operation of circuit 16, so that receiver 4 will get ready for reception. Simultaneously, the radio equipment also detects the extraction of receiver 4 and then uses the control channel to base station 29 to send a getting-off registration signal, including the subscriber's number, to base station 29. On receiving the getting-off registration signal, base station 29 stores it in memory circuit 26 and then sends a getting-off registration confirmation signal to the mobile station. The mobile station, having received it, turns off the electric power source automatically.