WO1991007028A1 - System for transmitting data between several subscriber stations in a local communications net - Google Patents

System for transmitting data between several subscriber stations in a local communications net Download PDF

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Publication number
WO1991007028A1
WO1991007028A1 PCT/EP1990/001818 EP9001818W WO9107028A1 WO 1991007028 A1 WO1991007028 A1 WO 1991007028A1 EP 9001818 W EP9001818 W EP 9001818W WO 9107028 A1 WO9107028 A1 WO 9107028A1
Authority
WO
WIPO (PCT)
Prior art keywords
pulse
radiation
stations
station
characterized
Prior art date
Application number
PCT/EP1990/001818
Other languages
German (de)
French (fr)
Inventor
Wolfgang Kemmler
Amer Amin
Original Assignee
Siemens Nixdorf Informationssysteme Aktiengesellschaft
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority to DEP3937096.8 priority Critical
Priority to DE19893937096 priority patent/DE3937096C2/de
Application filed by Siemens Nixdorf Informationssysteme Aktiengesellschaft filed Critical Siemens Nixdorf Informationssysteme Aktiengesellschaft
Publication of WO1991007028A1 publication Critical patent/WO1991007028A1/en

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Classifications

    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04BTRANSMISSION
    • H04B10/00Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/11Arrangements specific to free-space transmission, i.e. transmission through air or vacuum
    • H04B10/114Indoor or close-range type systems
    • H04B10/1149Arrangements for indoor wireless networking of information

Abstract

The invention concerns a system for transmitting data in half-duplex operation between several subscriber stations (10, 12) in a local communications net, transmission taking place between a subscriber station (10 or 12) and a sub-station (18 or 20) by modulated electromagnetic radiation. The invention calls for data transmission between the sub-stations (18, 20) also by electromagnetic radiation. To transmit binary data, this radiation is impulse-modulated. The sub-stations (18, 20) each emit a pulse in response to the arrival of a pulse. Following arrival of a pulse, the stations (10, 12, 18, 20) are not in a condition to receive at least for a time T equal to the sum of (a) twice the pulse transit time ti between the emitter station and the receiver station located furthest away within emitter range R and (b) the pulse length tp. The new system is highly flexible and can be set up with simple resources.

Description

System for transmitting data between a plurality of subscriber stations of a local Kommunikationsne zes

The invention relates to a system for transferring data in the half-Düplexbetrieb between multiple participants stations of a local communications network via at least two Zwischensta ion, wherein the Datenüber¬ transmission is performed between each subscriber station and an intermediate station by modulated radiation in space.

Such a system for data transmission on a local area network in the field of computer-aided manufacturing (CIM) is used is known from an article "Datenüber¬ transmission with Infrarotl layer" in the Fachzeitschrif electronics 24 / 25.11.1988, pages 82 to 90, known , Several Zwischenstat ones provide the wireless connection Ver¬ forth in a spacious factory hall by means of an infrared transmission link to subscriber stations of a flexible transport system. The intermediate stations are interconnected via lines and connected to a central computer, which takes control of the traffic. The Datenüber¬ transmission takes place in half duplex operation in which sends a Te lnehmersta either ion or receives data, a simultaneous data traffic is not provided in both directions.

In this known system which usually mounted on the ceiling of the space between stations must be unterein¬ other connected through a permanent data line network. In an extension of such a system to a larger indoor space or .One amendment of the transmission system, in which the subscriber stations are assigned new locations, consuming installation works for the Leitungs¬ network are required.

It is an object of the invention to provide a new system for transmitting data, which has a high Flexibi¬ formality and can be realized with- simple means.

This object is achieved for a system of the initially mentioned kind in that the data transmission zwi¬ rule takes place the identically constructed intermediate stations by radiation, that the radiation to übertra¬ gen binary data of a pulse modulation is subjected in that the intermediate stations each take on the input a pulse emit a pulse, and that the reception standby after the arrival of a pulse at rest for at least a time T which is equal to the sum of twice the pulse transit time between the sending station and the remote within the transmission range farthest receiving station and from the pulse duration ,

For data transmission, the pulse modulation is used in the invention. In this the following on a pulse interval is varied depending on the binary value of the data to be transmitted. The binary value 1 is assigned a short break, for example, a long pause, the 0. The pulse duration itself, ie the time that is emitted in the radiation is such that the switched on receiving Zwischensta¬ functions and the subscriber stations can receive the pulse safely.

This type of modulation, the radiation energy required for data transmission is minimal, since the information is contained in substantially the length of the pause. duration by selecting a short pulse can be high energy for a given amount of Strahlungs¬ the pulse amplitude, so that a large transmission range and a high signal to noise ratio ge genüber the ambient radiation is achieved.

There are also other types of pulse modulations ein¬ settable. For example, a modulation can be performed with fixed period in which the binary In¬ formation in successive predetermined cut Zeitab¬ constant length is encrypted. This can be done so that the transmission of a Strahlungs¬ pulse within a period of time is interpreted as a binary value. 1 The absence of such a pulse is then interpreted as a binary 0th

The light emitted in all directions generally loses momentum due to the divergence of the radiation and due to scattering and absorption in air, and of particles along its propagation path in intensity. Accordingly, a transmission range can be de¬ finishing that specifies the distance at which still present a sufficiently good receive signal for the respective subscriber station or intermediate station. this is decisive compliance with a predetermined Störab¬ prior to spurious signals such as noise, background radiation and spurious radiation. The received by an intermediate station in the range of a transmitting station pulse triggers the emission of a new pulse is received within their reach, in turn functions of Zwischensta¬. These stations then send additional pulses, so that an initially emitted from a subscriber station pulse triggers a plurality of additional pulses which propagate in the manner of a shaft, the functions Zwischensta¬ the respective received pulses attenuated amplified transmit again. The Ausbreitungsgeschwin¬ speed of the wave depends on the theory Licht¬ speed in air. Practically, however, delays are to be considered which are caused in particular by reaction times and the transient response of the electronic components.

send the similarly constructed intermediate stations their impulses generally in all directions and impulses from all directions can receive. This means that the intermediate stations after Aus¬ send a pulse of them adjacent Zwischen¬ stations again receive impulses. These pulses would cause no further action sending new Im¬ pulses that are not in connection with the data to be transmitted and thus disturb the Übertra¬ supply. For suppressing these pulses, the invention provides that the Empfangs¬ readiness rests a transmitting station for a time T. During this time, incoming pulses can trigger any new impulses. The time T is at least the sum of twice the pulse transit time between the sending station and the remote within the transmission range farthest receiving station and from the pulse duration. This measure is also ensures that the er¬ witnessed by crosstalk transmitted from the station or by reflection from obstacles in the transmission pulses are suppressed, and consequently receive k.eine missing pulses and will be sent out again. The receptivity of the subscriber stations suspended for the time T, so that their data reception is not disturbed by zu¬ back next impulses.

Since in the invention the data transmission between the intermediate stations takes place by radiation, eliminating the installation of a cable network for the Zwischensta¬ functions. The spatial extension of an existing data transmission system is therefore feasible without great technischen effort because easily wei ^ - be arranged direct between stations in space nen kön-.

Furthermore, the system required by the invention, no central control for data traffic, as is the case in the prior art, since the data transmission can be asynchronous and intermediate stations von¬ operate independently of each other without disturbing each other. The intermediate stations themselves are very simple, because they have to meet any memory function as well as any signal processing function. They can be by simple electronic means Sieren reali¬.

The system of the invention allows a high Ubertra- to transmission speed and data transfer rate, since the transmission of the data from a transmitting to a receiving subscriber station is almost with Licht¬ speed. The pulse repetition frequency for transmission is affected in addition to the defined by the Impulsmodu¬ lation pulse intervals by the time T, in readiness to receive the Statio¬ nen rests. The time T is true be¬ next to the pulse duration by the pulse transit time between the stations, which in turn depends on the speed of light in air as well as the transmission range. The latter can be optimized so that the time T is minimal. Advertising the pulses of short pulse duration is used, then a high pulse repetition rate and thus achieve a high data transfer rate can.

As a radiation to both visible light and infrared radiation may be used. The latter has the advantage that parts using simpler electronic Bau¬ such as light-emitting diodes in pulsed operation a high radiation intensity and thus a high transmission range is achieved. In cases of applications in which the electromagnetic Verträglich¬ ness is not critical, can be used as radiation, electromagnetic radiation in the radio frequency range or in the micro range elle.

A preferred embodiment of the invention is da¬ characterized by that in a Reaktions¬ a time-delayed emission of the pulse lengthening the time T zu¬ additionally at least this reaction time. The reaction time is determined by the switching time as well as by the delay inductive and capacitive components of the electronic components in the Zwi¬ rule stations caused. Since by means of said Ma߬ took the unfavorable timing of such components can be compensated, it is possible to use very simple and inexpensive electronic components with long response times at the circuit implementation of the intermediate stations.

In a further embodiment of the invention it is provided that the intermediate stations are arranged at equal intervals. The Zwi¬ rule stations then form which is composed of equilateral triangles at the corners thereof, respectively, an intermediate station is arranged a connection network. By this arrangement it is achieved that each Zwischen¬ station, except for those which are arranged on the edge of the net zes from six directly neighboring stations Zwi¬ rule is surrounded. In case of failure of one or even more of these stations is still stet gewährlei¬ that the emitted pulse tion of a remaining adjacent Sta¬ can still be received and so the further pulse transmission is ensured. This means that the system rule stations even in case of failure einzel¬ ner Zw very reliably. Further, a high and consistent density gleich¬ at intermediate points in space is achieved by this arrangement, so that a data transmission from a subscriber station to another can be done reliably in space regardless of the location of the Teilnehmerstat¬ ion.

A further development of the embodiment described provides that the distances are equal to the transmission range. By this measure, the number of required intermediate stations minimal and the technical complexity of the system is reduced.

An embodiment of the invention will be explained below with reference to the drawing. In which:

Fig. La a series of pulses according to the pulse modulation Im¬ with variable pulse pauses,

Fig. Lb a sequence of pulses with a fixed time raster,

Fig. 2 stops an arrangement with two Teilnehmer¬ and two intermediate stations, Fig. 3 shows a schematic structure of the elek¬ tronic components of a rule Zwi¬ station in a Blockdarstel¬ lung,

Fig. 4 experimental results for determining the

Transmission range represented in a

Diagram,

Fig. 5 shows pulse diagrams over time for two intermediate stations whose distance from each other slightly less than the Sendereichwe te is

Fig. 6, the propagation of pulses at a plurality of intermediate stations in space,

Fig. 7 shows pulse diagrams over time for three intermediate stations, which are within a transmission range, and

Fig. 8 a, b a directional characteristic with a main lobe and two side lobes for the abge¬ beamed from an intermediate station, and a radiation halb¬ omnidirectional.

In Fig. La pulse trains are over the time t for the used for the transmission of binary data Impulsmodula¬ tion. Radiation pulses with the pulse height H and the duration tp be over time t with unter¬ retired union breaks to, tl emitted. A short break tO corresponds to the binary value 0, a long pause tl the binary value 1. The pulse duration tp is intended to lichst mög¬ be short so that the emitted radiation • energy pulse height H is large or small so that at a given radiation energy. This pulse height H essentially determines the transmission range and signal to noise ratio to noise.

Another possible type of pulse modulation is shown in Figure lb.. In this modulation, a spring-stes time pattern of the length t2 is used. Occurs inner¬ half a period of time t2, a pulse of duration tp, so this corresponds to B, then this is interpreted as a binary value B = 1 is missing within a time interval t2 = 0, such a pulse to the binary value. The duration tp of the pulse must reach maximum-section, the length t2 of the Zeitab¬. Preferably, the pulse duration tp is chosen substantially smaller than the length t2 in order to obtain a large pulse height H with a predetermined pulse energy.

In FIG. 2, the basic structure of the system for schematically transfer of data between two Teilnehmerstat¬ ion-lo, 12 through two intermediate stations 18, shown in a space 20. The subscriber stations 10, 12, for example, computer terminals, personal Compu¬ ter with a communication interface, Ar¬ beitsstationen be for computer-aided manufacturing or automated teller stations and are located near the floor of the room. The subscriber stations 10, 12 are mobile, meaning they can be depending on the application in different places of the room.

The subscriber stations 10, 12 each have a

Transmitter Empfängereinhei 14 and 16, each having a matching with a stop structure which is described in more detail. The transmitter Empfängereinhe s 14, 16 have a spherical directivity pattern 15 to be received and abzu¬ ray radiation and are aligned with them benachbar¬ th intermediate stations 18 and 20 respectively. Thereby, the interference of the transmission path between the intermediate station 18 or 20 and the respective subscriber station 10 improves 12th

The traffic between the subscriber stations 10, 12 and executed under the half-duplex operation. This means that the subscriber stations 10, 12 abwech¬ nately send and receive data. For transmitting binary data is one of the Sendei-receiver unit 14, tivated ak¬ 16, the data pulses in the form of modulated radiation emitting, which are forwarded by the intermediate stations 18, 20 in the room. All the subscriber stations 10, 12 of the room, these pulses via their respective Sends receiver units 14, 16. The pulses are then counted aus¬ in the subscriber station 10, 12 by known methods and the corresponding data weiter¬ processed.

The 'intermediate stations 18, 20 are arranged on the ceiling 24 of the room at a distance from one another which corresponds at least to the transmission range of the intermediate stations 18, 20th As the radiation, infrared radiation is used with a typical semiconductor sources of radiation wavelength of about 1 micron. For suppression of the background radiation and the Stör¬ radiation by ambient light are the Empfangs¬ elements of the intermediate stations 18, 20 and the transceiver units 14, 16 with filters (not darge sets) whose wavelength is tuned to the radiation of the semiconductor radiation sources. The intermediate stations 18, 20 are each made of a power supply (not shown) supplied with power.

The circuit design of an intermediate station 18, 20 and a transmitter-receiver unit 14, 16 is shown in a schematic representation in Fig. 3. A reactor equipped with a photodiode receiving module 26 detects a pulse 25 which has been emitted from an intermediate station or a transmitter-receiver unit of a subscriber station, and converts it into an electrical signal. This is fed via a switch arrangement 28 to a preamplifier 30 whose impedance is the receive block 26 for a low noise amplification mög¬ lichst adjusted. The output signal of the amplifier 30 is fed to a threshold switch 32, which compares it with a given threshold vor¬ 31st the output signal exceeds this threshold 31, the threshold value delivers a signal 33, based on which the presence of a valid pulse can be detected 25th The signal 33 can then at a transmitter-receiver unit 14, 16 formation for evaluating the binary In¬ be used in a subscriber station.

The signal 33 is further guided to a pulse shaping stage 36 zu¬ which generates a control pulse having the pulse width tp and a diode array drives 38th The diode array 38 consists of a plurality of sparse ttieren¬ diodes (LED), infrared radiation of wavelength emit about 1 micrometer. The diodes operate in so¬ said pulse operation, that its pulse interval is we¬ sentlich greater than the time in which they send aus¬ radiation. This makes it possible to apply the diodes with high pulse currents that generate a high irradiance. By using mehre¬ rer diodes, the total radiated power is increased, and by different orientation of the diodes, the radiation may be radiated in a large solid angle.

The output signal 33 of the trigger 32 is also supplied to a timer 34, which 28 opens the switching path of the switch assembly for a vorge passed time T. In this time T from the reception module 26 detected pulses 25 is not transmitted to the preamplifier 30, so that the Schwell¬ value switch 32 does not output a signal 33 which Siert a gül¬ term pulse signal.

A emitted from the diode array 38 pulse 40 is attenuated along its propagation path due to the divergence Strahlungs¬ as well as the dispersion and absorption of radiation in air. This leads to a be¬ excluded transmission range of the intermediate stations 18, 20 and the subscriber stations 10, 12. Fig .. 4 is a diagram showing experimental results for determining the Sendereichweite.Über the distance s, from the sending station 14, 16, 18 20 is the switch in front of the Schwellwert¬ 32 (Fig. 3) can be tapped off the output voltage U of the preamplifier 30 is applied. With increasing distance s this voltage U decreases hyperbolically and reaches at a distance of s = 13.5 m a critical value of 0.5 V, below the reliable detection of the pulse is no longer possible. This limiting distance is called the transmission range R. The critical value of 0.5 V is used as the threshold value 31 in the comparison threshold in the 32nd

In FIG. 5, timing diagrams are plotted against time t darge provides that Zwischensta¬ the transmission of impulses between two within the transmission range R lying functions 42, 44 Show. A time t = 0 emitted from the intermediate station 42 pulse 48 reaches the intermediate station 44, but not the distant and lying outside of the transmission range R station 46. The pulse 48 meets with a time Verzöge¬ tion ti, the run time of the radiation in air to station 44 corresponds to a station in the 44th After a reaction time tr, which is caused by switching times of the electronic components of the intermediate station 44, the station 44 sends a pulse 50 in all directions. Subsequently, in the above senden¬ the station 42 incoming pulse 50 will be considered in more detail below. He meets after the pulse running time ti at the station 42 and would stay there without further countermeasures again a consequence pulse sen auslö¬. This would result in the further course to the fact that the stations 42, 44 at a time interval ti exchange continuously receive new impulses. The transmission of binary information would therefore not possible.

According to the invention the receiving readiness of the station 42 by transmitting their pulse 48 is stopped for a time T, so that during this time arrival T pulses coming kön¬ trigger any further pulses NEN. This time T must T tr + ti + ti + tp satisfy according to the diagram in Fig. 5 the relationship. Only way to ensure that the station 42 emits no disturbing consequence impulses. The excluded sent from the station 44 pulse 50 is received by the station 46 and triggers a pulse sequence from there. Whose intensity is too small to be detected at the station 42 as valid pulse. In FIG. 6 diagrams a) are provided to transfer data between a plurality of Teilnehmerstat¬ ion 52 to 58 of a local communications network to e) dar¬ in five. The subscriber stations 52 to 58 are marked by a triangle. For data transmission, a plurality of marked by circles is Zwi¬ rule stations provided which form a transmission network. The intermediate stations are from each other stands arranged in equal Ab¬, as is indicated by the dashed circle 60 in the diagram a). The distances between the intermediate stations are equal to the transmission range R.

In the representation b) the subscriber station 52 sends a pulse, the her standing next intermediate station receives. This then sends a subsequent pulse, which is received as shown c) of two adjacent intermediate stations. The simultaneous reception of these pulses is characterized by a connecting line. This connection line may be regarded as a wave front propagating pulses.

In the illustration d) this wave front is advanced by additional intermediate stations and achieved in the Dar¬ position E), the subscriber station 54, which is remote from the subscriber station 52 at the furthest. To transfer data from station 52 to station 54, so the pulses of the sending subscriber station 52 are pass on overnight stopovers. The subscriber stations 56 and 58 receive the ausgesand¬ th data already after five forwarding the Im¬ pulse by intermediate stations.

in Fig. 7 further timing diagrams of time t are shown, the information on the required "time T for the suspension of the readiness to receive a station type, if located in the transmission range R several Sta¬ functions are at different distances to the transmitting Sta¬ tion. in the upper part of FIG. 7 is a station 60 transmits, this may be an intermediate station or a subscriber station, a pulse 66 of which is well-received by both a station 62 as well as from a more distant station 64. the pulse 66 required to overcome the removal of the term ti, as the returned from the station 62 pulse 68. for a better understanding of the relationships described below was to station 62 in die¬ sem example, the response time tr is set to zero.

The pulse 66 is required until the arrival at the Wei ter remote station 64, the running time ti '. The same term ti 'also has the returned from the station 64 to the station 60 pulse 70. For störungs¬ free data transfer is, as can be seen from Fig. 7, necessary that the Recept-igsberei tschaft the station 60 for at least the time T rests, resulting from the relationship T> ti '+ t' + tp. At that time T is still to be added, which has been neglected in this example, the response time tr. It is therefore necessary to determine that the time T is essentially determined by the pulse transit time ti 'between the transmitting station 60 and the fernten within the transmission range of most ent receiving station 64th

The directional characteristic of the radiated from an intermediate station radiation has a decisive influence on the transmission range R. In Fig. 8a is a Ausfüh¬ approximately such an intermediate station 72 shown, the emitted radiation has a rotationally symmetrical directional characteristic with a spherical main lobe 74 and two side lobes 76, 78. The intermediate station 72 is attached beneath the ceiling 24 of the room. The main lobe 74 has an axis 86, parallel to the chennormale Flä¬ extends the ceiling 24th In the radiation area of ​​the main lobe 74 preferably are subscriber stations are usually located near the bottom of the suede there are. The side lobes 76, 78 have axes 82, 80 which extend parallel to the ceiling 24th In the direction of these axes 82, 80 lie adjacent Zwischen¬ stations. Through this directivity it is achieved that the radiated energy is preferably emitted both in the direction of the subscriber stations and in Rich¬ processing the intermediate stations so that ei¬ minimized nerseits energy consumption and subsequently the other hand, a large transmission range is achieved.

In Fig. 8b, the intermediate station 72 has an approximately hemispherical directivity pattern 90, that is radiated into the space radiation intensity - indicated by arrows 91 to 94 - is the same for all the solid angle of the half-space. Such a directional characteristic of 90, for example, can be generated on a substrate by arranging a plurality of radiation-emitting semiconductor components, such as for example LEDs or laser diodes. The components are oriented so that the principal axes of their radiation pointing in different directions and extend along the normal to the surface of a hemisphere whose center axis shows the inner to Raum¬. The resulting radiation intensity in the room is then constant for all solid angle approximately.

Claims

P atentanspr ü che
1. System for transmitting data in half-duplex mode between a plurality of Teilnehmersta¬ functions of a local communications network via at least two intermediate stations, said Da¬ tenübertragung merstation between each Teilneh¬ and carried by an intermediate station modulated radiation in space, characterized denotes ge, that the data transmission rule zwi¬ the similarly constructed Zwischenstatio¬ NEN (18, 20, 42, 44, 46, 60, 62, 64) that the radiation binary for transmitting data of a pulse modulation is subjected, is carried out by Strah¬ lung that the between stations (18, 20, 42, 44, 46, 60, 62, 64) emitting a pulse in each case on the arrival of a pulse out and in that the readiness to receive after the arrival of a pulse at rest for at least a time T which is equal to sum of twice the pulse time delay ti, ti 'between the transmitting station (10, 12, 42, 60) and the farthest within the transmission range R remote receiving station (44, 64) ud from the pulse duration tp is.
2. System according to claim 1, characterized in that in a to a reaction time tr verzö¬ siege transmission of the pulse, the time T is extended by at least additional borrowed, this reaction time tr ver¬.
3. System according to claim 1 or 2, characterized gekenn¬ characterized in that the ion Zwischensta are spaced at equal intervals gro¬ SEN.
4. System according to claim 3, characterized in that the distances equal to the Sendereichwei e R.
5. System according to any one of the preceding claims, characterized in that the radiation
Infrared radiation is used.
6. System according to any one of the preceding claims, characterized in that for the radiation of each intermediate station (18, 20, 42, 44, 46, 60, 62, 64) is a light emitting Halbleiter¬ least radiation source provided.
7. System according to any one of the preceding claims, characterized in that the stations of the
(10, 12, 18, 20, 42, 44, 46, 60, 62, 64) ab¬ radiation radiated a spherical (15) or a hemispherical directional characteristic (90).
8. System according to any one of the preceding claims, characterized in that in intermediate stations (7.2) attached to the ceiling (24) of the space montier¬ are bar, the emitted radiation has a rotationally symmetrical directional characteristic with a main lobe (74) and two side lobes (76 , 78), and in that the main beam axis (86) pa¬ rallel to the surface normal of the ceiling (24) and the side lobe axes (80, 82 extend) kenfläche parallel to DEK-.
9. System according to any one of the preceding claims, characterized in that the Teilnehmerstatio¬ NEN (10, 12) each having a transmitter-receiver unit (14, 16) with a directional characteristic (15) for the to be received and radiated radiation and have an them adjacent Zwischensta¬ tion (18, 20) are aligned.
10. System according to any one of the preceding claims, characterized in that the stations of the
(10, 12, 18, 20) received radiation is filtered by an optical filter, the emitted to the wavelength range of from the intermediate stations (18, 20) and the subscriber stations (10, 12) radiation is tuned.
PCT/EP1990/001818 1989-11-07 1990-10-31 System for transmitting data between several subscriber stations in a local communications net WO1991007028A1 (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
DEP3937096.8 1989-11-07
DE19893937096 DE3937096C2 (en) 1989-11-07 1989-11-07

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP51514690A JPH0793626B2 (en) 1989-11-07 1990-10-31 Data transmission system between a plurality of subscriber stations in the local communication network

Publications (1)

Publication Number Publication Date
WO1991007028A1 true WO1991007028A1 (en) 1991-05-16

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EP (1) EP0571366A1 (en)
JP (1) JPH0793626B2 (en)
DE (1) DE3937096C2 (en)
WO (1) WO1991007028A1 (en)

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WO1994011832A1 (en) * 1992-11-09 1994-05-26 Pricer Norden Ab Method and device for acknowledgement of transmitted information
WO1995023389A1 (en) * 1994-02-23 1995-08-31 Pricer Ab Method and device for acknowledgement
WO1995034963A1 (en) * 1994-06-16 1995-12-21 Iml Ltd. Free space communications system employing line of sight radiation

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DE4026073A1 (en) * 1990-08-17 1992-02-20 Telefunken Systemtechnik Control point coupling mobile data terminal to fixed data processor - has two components forming transceiver for electromagnetic waves, and air path as transmission line
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DE10116838C1 (en) * 2001-04-04 2002-11-28 Siemens Ag A process for half duplex transmission of information between communication devices with repeaters

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Publication number Priority date Publication date Assignee Title
WO1994011832A1 (en) * 1992-11-09 1994-05-26 Pricer Norden Ab Method and device for acknowledgement of transmitted information
US5729695A (en) * 1992-11-09 1998-03-17 Pricer Inc. Method and device for acknowledgement of transmitted information
WO1995023389A1 (en) * 1994-02-23 1995-08-31 Pricer Ab Method and device for acknowledgement
WO1995034963A1 (en) * 1994-06-16 1995-12-21 Iml Ltd. Free space communications system employing line of sight radiation
AU693564B2 (en) * 1994-06-16 1998-07-02 Iml Ltd. Free space communications system employing line of sight radiation

Also Published As

Publication number Publication date
JPH04505083A (en) 1992-09-03
EP0571366A1 (en) 1993-12-01
DE3937096A1 (en) 1991-05-08
DE3937096C2 (en) 1991-11-21
JPH0793626B2 (en) 1995-10-09

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