EP1002375A1 - Procede et dispositif de production d'une sequence de nombres aleatoires pour des frequences porteuses dans une transmission en radiotelephonie mobile - Google Patents

Procede et dispositif de production d'une sequence de nombres aleatoires pour des frequences porteuses dans une transmission en radiotelephonie mobile

Info

Publication number
EP1002375A1
EP1002375A1 EP97938761A EP97938761A EP1002375A1 EP 1002375 A1 EP1002375 A1 EP 1002375A1 EP 97938761 A EP97938761 A EP 97938761A EP 97938761 A EP97938761 A EP 97938761A EP 1002375 A1 EP1002375 A1 EP 1002375A1
Authority
EP
European Patent Office
Prior art keywords
shift register
bit
carrier frequencies
addition
content
Prior art date
Legal status (The legal status 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 status listed.)
Withdrawn
Application number
EP97938761A
Other languages
German (de)
English (en)
Inventor
Jürgen KOCKMANN
Uwe Sydon
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Siemens AG
Original Assignee
Siemens AG
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
Application filed by Siemens AG filed Critical Siemens AG
Publication of EP1002375A1 publication Critical patent/EP1002375A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/24—Radio transmission systems, i.e. using radiation field for communication between two or more posts
    • H04B7/26—Radio transmission systems, i.e. using radiation field for communication between two or more posts at least one of which is mobile
    • H04B7/2628—Radio transmission systems, i.e. using radiation field for communication between two or more posts at least one of which is mobile using code-division multiple access [CDMA] or spread spectrum multiple access [SSMA]
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
    • H04B1/69—Spread spectrum techniques
    • H04B1/713—Spread spectrum techniques using frequency hopping
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
    • H04B1/69—Spread spectrum techniques
    • H04B1/713—Spread spectrum techniques using frequency hopping
    • H04B1/7143—Arrangements for generation of hop patterns

Definitions

  • the present invention relates to a method and a device for generating a random number sequence which is converted into carrier frequencies for a mobile radio transmission.
  • the so-called frequency hopping spread spectrum system is known as a method for transmitting data on a plurality of carrier frequencies.
  • a frequency hopping spread spectrum system is understood to mean a system in which a large number of carrier frequencies are provided for radio transmission of data and the carrier frequency currently used is changed periodically.
  • the carrier frequency can be changed after each time slot or time frame of the time division multiplex transmission (or multiples thereof).
  • TDMA time division multiplex
  • Such a frequency hopping spread spectrum system has advantages in that the energy of the entire radio transmission is distributed over all carrier frequencies. This is particularly important if a generally available frequency band, such as the 2.4 GHz ISM (Industrial, Scientific, Medical) band, is used.
  • a further advantage of the frequency hopping spread spectrum system is that the system is made less sensitive by providing a large number of carrier frequencies. against disturbances.
  • the system is more secure against eavesdropping from third parties, since the third party generally does not know which carrier frequency is to be changed after a certain period of time.
  • the sequence of carrier frequencies that are used for transmission in succession is determined by an algorithm.
  • Such an algorithm is implemented in an identical manner in the base station and in each mobile station of the mobile radio transmission. If a handset is thus synchronized with the associated base station, the handset and the base station will synchronously carry out the carrier frequency changes specified by the sequence of the (identical) algorithm.
  • the algorithm should ensure that each carrier frequency is used the same number of times and for the same length of time over a period of time.
  • the object of the present invention is therefore to create a method and a device for generating a random number sequence for carrier frequencies of a mobile radio transmission, which enable a random number algorithm to be implemented in a simple manner.
  • a method for generating a random number sequence is thus provided, the random number sequence being converted into carrier frequencies for a mobile radio transmission.
  • a shift register with n bits is provided. This is followed by a feedback modulo2
  • the step of converting the content of the shift register into carrier frequencies for a mobile radio transmission comprises adding the content of the shift register to the current carrier frequency. It is then decided whether the result of the addition is greater than the number of carrier frequencies present. In the event that the decision is positive, the addition result is then reduced by the number of available carrier frequencies until the decision is negative, i.e. until the result of the addition is no longer greater than the number of available carrier frequencies. In the event that the decision is negative, the addition result is used as the next carrier frequency. The shift register is then shifted by one bit and the process begins again.
  • a device for converting a random number sequence into carrier frequencies fx for ne cellular transmission has a shift register with n bits. Furthermore, an addition device for modulo2 addition of one bit of the shift register with one or more other bits of the shift register is provided in the manner of a feedback. After the addition, the register content is shifted clockwise by one bit, preferably to the right. The result of the adder is then inserted into the bit position that has been freed by the shift. Furthermore, a device for converting the content of the shift register into a carrier frequency for a mobile radio transmission is provided.
  • the type of feedback i.e. the bits used for the modulo2 addition and their number can be changed in order to generate different sequences.
  • the device for converting the content of the shift register into carrier frequencies also has means for adding the content of the shift register to the current carrier frequency. Means are also provided for deciding whether the result of the addition is greater than the number of available carrier frequencies. In the event that the decision is positive, the addition result is reduced by the number of available carrier frequencies until the decision is negative, i.e. until the result of the addition is no longer greater than the number of carrier frequencies present. In the event that the decision is negative, the addition result is used as the next carrier frequency and then the shift register is shifted clockwise by one position.
  • the shift register preferably has 16 bits.
  • the shift register can be implemented in an 8 bit or 16 bit processor.
  • the invention further relates to a mobile radio device which has a device of the type mentioned above.
  • FIG. 1 shows a mobile radio transmission system with a base station according to the invention
  • FIG. 3 shows in detail the internal structure of a base station according to the invention.
  • Fig. 4b the content of the shift register for the different clocks of a period
  • FIG. 5 shows a flowchart for converting the random number sequence into carrier frequencies.
  • the arrangement for radio transmission of data has a base station 1 and several mobile parts (mobile stations), wireless telephones 2, 3 ....
  • the base station 1 is connected to the fixed network by a terminal line 10.
  • An interface device which is not shown, can be provided for communication between the base station 1 and the terminal line 10.
  • the base station 1 has an antenna 6, by means of which, for example, a first radio transmission communication path 8 with the handset 2 or via a second radio transmission path 9, communication with the handset 3 takes place.
  • the handsets 2, 3 ... each have an antenna 7 for receiving or transmitting data.
  • Fig. 1 the state is schematically shown in which the base station 1 actively communicates with the mobile part 2 and thus exchanges data.
  • base station 1 The internal structure of base station 1 is shown schematically in FIG. 1.
  • the voice information data are supplied to an RF module 4, which is controlled by a carrier frequency sequence unit.
  • RF module 4 which is controlled by a carrier frequency sequence unit.
  • the exact structure of a base station 1 according to the invention will be described later.
  • the duration of a time frame is 10 ms, and there are 24 time slots Zx, namely twelve time slots for the transmission from the base station to handsets and a further twelve time slots Zx for transmission from the handsets to the base station.
  • ten carrier frequencies fx between 1.88 GHz and 1.90 GHz are provided.
  • the present invention also finds particular application for transmissions in the so-called 2.4 GHz ISM (Industrial, Scientific, Medical) frequency band.
  • the generally accessible ISM frequency band has a bandwidth of 83.5 MHz.
  • at least 75 carrier frequencies fx must be distributed over this 83.5 MHz.
  • a division of the bandwidth from 83.5 MHz to 96 carrier frequencies is particularly advantageous, i. H. a channel spacing of 864 kHz.
  • the frequency bands and standards mentioned above are given purely as an example.
  • the basic requirement for applicability in the present invention is only that a frequency hopping spread spectrum is used, i. H. that several carrier frequencies are available and that the carrier frequency selected for transmission is changed periodically. For such a change, it is advantageous if the data are transmitted in time slots Zx (time division multiplex method).
  • the DECT standard and any other modified standard based on this DECT standard are suitable.
  • the RF module 4 is supplied with information data if the base station 1 is to transmit to a mobile unit 2, 3... By means of the antenna 6 and is transmitted by the HF Module 4 outputs information data when data is received from handsets.
  • the RF module 4 modulates the digitally coded information data onto a carrier frequency fx.
  • the carrier frequency fx currently to be used is predetermined by a carrier frequency sequence unit, which is generally designated 20.
  • a detection device 24 is provided in the carrier frequency sequence unit 20, to which the demodulated signal is supplied by the RF module 4. Interference means that there is either an interference in the proper sense or an assignment by another transmitter.
  • a disturbance in the sense of the present description can thus be detected, for example, by demodulating a received signal on a carrier frequency and detecting whether a signal level is present on this carrier frequency or not.
  • a disturbed carrier frequency is a carrier frequency onto which a signal is modulated that exceeds a certain threshold value.
  • Faults in the actual sense can be detected by the occurrence of CRC errors or burst losses.
  • the detection device 24 thus uses the demodulated signal from the RF module 4 to determine how high the signal component modulated onto a specific carrier frequency fx is.
  • the detection device 24 sends a fault detection signal to a blocking / releasing unit 21. / Release unit 21 a blocking / release information to a processor 23.
  • This blocking / release information indicates which of the carrier frequencies fx are blocked or released again due to the detection of a fault by the detection device 24, as will be explained later.
  • An independent procedure is thus created by means of the detection device 24 and the blocking / enabling device 21, by means of which disturbed frequencies can be blocked and released again.
  • the processor 23 is supplied with a sequence from a random number generator 22.
  • the random generator 22 On the basis of a random algorithm implied in the random generator 22 generates a randomly distributed sequence of carrier frequency values within the predetermined frequency band.
  • the random number generator 22 thus executes a procedure which is independent of the procedure for frequency blocking in the event of a fault.
  • the processor 23 finally sends a control signal to the RF module 4, which specifies the carrier frequency value to be used for the RF module 4.
  • the processor 23 specifies how many different values it is to generate. This number of values to be generated corresponds to the number of carrier frequencies to be generated, which must be at least 75, for example in accordance with the US specification “FCC part 152.
  • the processor 23 also provides the random number generator 22 with a starting value for its algorithm.
  • the mobile station receives this start value from the base station for synchronization, which is achieved by using the same start value and the same algorithm. With the same starting value and the same algorithm, the same sequences are forcibly generated by the base station and the handset.
  • Base station 1 is the master in frequency allocation, ie at the start of a connection establishment, the random number generator in a mobile part is initialized with the state of random number generator 22 of base station 1. On- finally, the random number generators in the handset 2, 3 ... and in the fixed station 1 generate the same carrier frequency values synchronously and independently of each other.
  • the procedure for frequency blocking which is carried out by the detection device 24 and the blocking / releasing unit 21, uses a unidirectional protocol on the air interface during the entire connection time between the base station 1 and a handset 2, 3. If the detection device 24 finds one of the possible frequencies fx as disturbed by the base station 1, the base station 1 thus informs all the mobile parts with which it operates connections that this disturbed frequency, if it is generated by the frequency of the random number generator is to be replaced by another carrier frequency which is not detected as being disturbed. The random number generator 22 is not influenced by the frequency blocking. This frequency blocking is withdrawn by the blocking / releasing unit 21 when the blocked carrier frequency is again suitable for transmission or when it was blocked for longer than a previously defined time.
  • the basis of the algorithm is a feedback shift register 25 with the length x, the length x being 4 in the example shown.
  • the shift register 25 is loaded with the value 0001 as shown. For each new value, the contents of the shift register 25 are shifted to the right by one bit, the left bit being recalculated as shown.
  • the type of feedback ie in the present example the modulo2 addition of the left bit with the rightmost bit of the shift register 25 can be changed.
  • the sequence length ie the periodicity after which the generated sequence is repeated periodically, is a maximum of 2 n- 1, where n is the number of bits in the shift register 25.
  • FIG. 4b shows how the content of the shift register 25 for the example shown in FIG. 4a is for the corresponding clocks of a period.
  • a 16-bit shift register can be used. Such a shift register can be easily implemented in 8- and 16-bit processors. Due to the different possibilities of the feedback 27, different sequences can be generated with a 16-bit shift register 2048.
  • a carrier frequency corresponding to a value of the generated random sequence is maintained for the duration of a frame of, for example, 10 ms
  • the duration of the period is 65535 x 10 ms «10.9 min. This means that a maximum length sequence in a 16-bit register is only repeated every 10.9 minutes.
  • the number of possible values of the sequence of the carrier frequencies is 65535 as explained.
  • the number of actually used carrier frequencies can be considerably smaller and moreover variable.
  • the carrier frequency cannot be obtained directly by converting the values of the random sequence.
  • FIG. 5 shows how the frequencies actually used are obtained in an endless loop from the content of the shift register 25.
  • the frequency fx n - ⁇ is first set to 0. Then the current content of the shift register 25 is added to this value (28). Then it is calculated and a decision is made as to whether the addition result calculated in step 28 is greater than the number y of the usable carrier frequencies fx. If the result of this decision 29 is positive, ie if the addition result in step 28 is greater than the number y of the actually usable carrier frequencies fx, then this value is reduced by the value of the number y of the usable carrier frequencies (30).
  • variable y By changing the variable y, the maximum number of frequencies used can be adjusted.
  • the invention thus enables the generation of random numbers by means of an algorithm that is simple to implement in a processor. At the same time, the computing time required is kept to a minimum.

Landscapes

  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Mobile Radio Communication Systems (AREA)

Abstract

L'invention concerne un procédé et un dispositif permettant de produire une séquence de nombres aléatoires, cette séquence servant à la transformation en fréquences porteuses (fx) pour une transmission en radiotéléphonie mobile. Un algorithme, qui est fondé sur un registre à décalage (25) à rétroaction (27) avec n bits, est utilisé. Un bit du registre à décalage (25) est, avec rétroaction (27), ajouté par addition modulo2, à un autre bit du registre à décalage (25). Le contenu du registre à décalage (25) est décalé, de façon cadencée, d'un bit vers la droite. Le résultat de l'addition modulo2 est introduit à l'emplacement de bit gauche libéré par le décalage. Ensuite, le contenu du registre à décalage (25) est transformé (23) en une fréquence porteuse (fx) pour une transmission en radiotéléphonie mobile. Pour ladite transformation (23) il est prévu d'utiliser un algorithme se présentant sous la forme d'une boucle sans fin.
EP97938761A 1997-08-14 1997-08-14 Procede et dispositif de production d'une sequence de nombres aleatoires pour des frequences porteuses dans une transmission en radiotelephonie mobile Withdrawn EP1002375A1 (fr)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/DE1997/001734 WO1999009668A1 (fr) 1997-08-14 1997-08-14 Procede et dispositif de production d'une sequence de nombres aleatoires pour des frequences porteuses dans une transmission en radiotelephonie mobile

Publications (1)

Publication Number Publication Date
EP1002375A1 true EP1002375A1 (fr) 2000-05-24

Family

ID=6918534

Family Applications (1)

Application Number Title Priority Date Filing Date
EP97938761A Withdrawn EP1002375A1 (fr) 1997-08-14 1997-08-14 Procede et dispositif de production d'une sequence de nombres aleatoires pour des frequences porteuses dans une transmission en radiotelephonie mobile

Country Status (3)

Country Link
EP (1) EP1002375A1 (fr)
CA (1) CA2300064A1 (fr)
WO (1) WO1999009668A1 (fr)

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4066964A (en) * 1967-01-06 1978-01-03 Rockwell International Corporation Communication system
EP0084967A2 (fr) * 1982-01-27 1983-08-03 The Marconi Company Limited Système de communication par radio
EP0287154A1 (fr) * 1987-04-17 1988-10-19 Hollandse Signaalapparaten B.V. Système de générateurs de codes orthogonaux, postes radio pourvus d'un générateur de code et générateur de code d'un tel système
WO1993017507A1 (fr) * 1992-02-28 1993-09-02 Telefonaktiebolaget Lm Ericsson Procede de communication d'un systeme radio mobile cellulaire amrt par saut de frequence

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
IL82561A (en) * 1986-05-27 1991-12-15 Fairchild Weston Systems Inc Secure communication system for multiple remote units
US5031129A (en) * 1989-05-12 1991-07-09 Alcatel Na Network Systems Corp. Parallel pseudo-random generator for emulating a serial pseudo-random generator and method for carrying out same
US5394433A (en) * 1993-04-22 1995-02-28 International Business Machines Corporation Frequency hopping pattern assignment and control in multiple autonomous collocated radio networks

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4066964A (en) * 1967-01-06 1978-01-03 Rockwell International Corporation Communication system
EP0084967A2 (fr) * 1982-01-27 1983-08-03 The Marconi Company Limited Système de communication par radio
EP0287154A1 (fr) * 1987-04-17 1988-10-19 Hollandse Signaalapparaten B.V. Système de générateurs de codes orthogonaux, postes radio pourvus d'un générateur de code et générateur de code d'un tel système
WO1993017507A1 (fr) * 1992-02-28 1993-09-02 Telefonaktiebolaget Lm Ericsson Procede de communication d'un systeme radio mobile cellulaire amrt par saut de frequence

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See also references of WO9909668A1 *

Also Published As

Publication number Publication date
CA2300064A1 (fr) 1999-02-25
WO1999009668A1 (fr) 1999-02-25

Similar Documents

Publication Publication Date Title
DE4447230C2 (de) Modulationsverfahren, Demodulationsverfahren, Modulator und Demodulator sowie Verwendung von Modulator und Demodulator
DE3787787T2 (de) Kommunikationssystem.
DE69736897T2 (de) Funkkommunikation mit bakenaussendung mit jitter
EP0012394B1 (fr) Circuit récepteur pour la synchronisation d'un génerateur pseudo-aléatoire avec un signal de réception transmis par un êmetteur
DE69916039T2 (de) Selbstinterferenzunterdrückung für relaisübertragungsnetzwerke
DE60023497T2 (de) Verfahren und einrichtung zur interferenzreduzierung zwischen basisstationen in einem breitband cdma-system
DE69215025T2 (de) System zur Verteilung von Funktelefonsignalen über ein Kabelfernsehnetz
DE69530713T2 (de) DS/FH-CDMA-System mit Sendeleitungsregelung
DE69831726T2 (de) Cdma mobile station und cdma übertragungsverfahren
EP1173943A1 (fr) Procede pour former et pour determiner une sequence de synchronisation, procede de synchronisation, unite d'emission et unite de reception
DE60124588T2 (de) Hybride spreizband-technik zur erweiterung der kanalkapazität
DE4021136A1 (de) Empfaenger fuer die datenuebertragung im bandspreizverfahren
DE2620368A1 (de) Vorrichtung zur funktionssteuerung fuer ein funksprechverbindungssystem
DE69735518T2 (de) Kommunikationsverfahren, Sendevorrichtung und Empfangsvorrichtung zur gleichzeitigen Verwendung von zwei Kommunikationsbetriebsmitteln durch variable Zuteilung
EP1002374B1 (fr) Procede et dispositif pour produire une sequence de frequences porteuses
EP1180270B1 (fr) Procede et dispositif pour effectuer des transmissions de donnees en simplex
WO1999009671A1 (fr) Procede et station fixe pour la transmission en radiotelephonie mobile
EP1088401B1 (fr) Procede et dispositif a diversite en frequence porteuse destines a la transmission d'informations par un procede a sauts de frequence
WO2006008305A1 (fr) Procede de transmission de signaux dans un systeme de communication
DE69533652T2 (de) Datenübertragungsverfahren und zellulares funksystem
DE60008195T2 (de) Verfahren und empfänger zur frequenzerfassung in einem frequenzsprungverfahren
EP1002375A1 (fr) Procede et dispositif de production d'une sequence de nombres aleatoires pour des frequences porteuses dans une transmission en radiotelephonie mobile
EP1002376B1 (fr) Procede et dispositif pour l'enregistrement d'une partie mobile dans une station fixe
WO1999009667A1 (fr) Procede et systeme de transmission pour la signalisation d'une frequence porteuse
DE102007028732A1 (de) Mehrfache Spreizung/Entspreizung von Spreizspektrumsignalen durch mehrfache Spreizfolgen

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

17P Request for examination filed

Effective date: 20000218

AK Designated contracting states

Kind code of ref document: A1

Designated state(s): DE ES FR GB IT

17Q First examination report despatched

Effective date: 20001020

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN

18D Application deemed to be withdrawn

Effective date: 20030121