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WO2003030425A2 - Procede informatique de generation de codes pseudo-orthogonaux destine a la transmission de donnees - Google Patents

Procede informatique de generation de codes pseudo-orthogonaux destine a la transmission de donnees Download PDF

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Publication number
WO2003030425A2
WO2003030425A2 PCT/IB2002/004017 IB0204017W WO03030425A2 WO 2003030425 A2 WO2003030425 A2 WO 2003030425A2 IB 0204017 W IB0204017 W IB 0204017W WO 03030425 A2 WO03030425 A2 WO 03030425A2
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WO
WIPO (PCT)
Prior art keywords
code
string
bit
value
pseudo
Prior art date
Application number
PCT/IB2002/004017
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English (en)
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WO2003030425A3 (fr
Inventor
Maria-Gabriella Di Benedetto
Maria Stella Iacobucci
Original Assignee
Universita' Degli Studi Di Roma 'la Sapienza'
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 Universita' Degli Studi Di Roma 'la Sapienza' filed Critical Universita' Degli Studi Di Roma 'la Sapienza'
Priority to AU2002338187A priority Critical patent/AU2002338187A1/en
Publication of WO2003030425A2 publication Critical patent/WO2003030425A2/fr
Publication of WO2003030425A3 publication Critical patent/WO2003030425A3/fr

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J13/00—Code division multiplex systems
    • H04J13/10—Code generation
    • H04J13/12—Generation of orthogonal codes
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J13/00—Code division multiplex systems
    • H04J13/0007—Code type
    • H04J13/0022—PN, e.g. Kronecker

Definitions

  • the present invention relates to a computer method for generating pseudo- orthogonal codes, in particular for data transmission.
  • CDMA code-division multiple-access
  • the second defined as frequency-hopping (FH), envisages that the carrier frequency will perform hops on a set of pre-defined values according to an appropriate sequence.
  • the third, time-hopping (TH) is a variant of pulse-code modulation (PCM), in which the position of a pulse within an assigned window is regulated by a code sequence.
  • PCM pulse-code modulation
  • the principle that underlies the CDMA technique is that the user information, which is typically a narrow-band information, is spread over a much wider band. Consequently, techniques are called for that enable maximum exploitation of the capacities of the communication channels, and this is rendered possible by the CDMA techniques. These guarantee a high quality of transmission, minimizing the interference between the information produced by different users via the use of appropriate codes.
  • Summary of the invention is to provide a computer method for generating pseudo-orthogonal codes for use with techniques of transmission of information of the CDMA type so as to minimize the signalling that the users have to exchange for setting up a communication.
  • Another purpose of the invention is to provide a computer program that will implement the computer method of the invention and that will be versatile and usable with general-purpose computers or else with main frame computers.
  • the above purposes, and others that will become apparent in the light of the ensuing description, are achieved by means of a computerised method for generating pseudo-orthogonal codes that has the characteristics specified in Claim 1 and by means of a computer program as specified in Claim 4. Thanks to the characteristics of the computer method and the computer program which implements it by means of computers, which employs both known algorithms and new algorithms, there is enabled a more efficient exploitation of both radio and cable communication channels.
  • Figure 1 illustrates a graph representing information transmitted according to a first variant of the CDMA technique, in which the computer method for generation of the pseudo-orthogonal codes according to the invention is used
  • Figure 2 illustrates a graph representing information transmitted by just one user according to a second variant of the CDMA technique, in which the computer method for generation of the pseudo-orthogonal codes according to the invention is used;
  • Figure 3 illustrates a graph representing information transmitted according to a second variant of the CDMA technique by multiple users, in which the computer method for generation of the pseudo-orthogonal codes according to the invention is used;
  • Figure 4 illustrates a graph representing information transmitted by just one user according to a third variant of the CDMA technique, in which the computer method for generation of the pseudo-orthogonal codes according to the invention is used;
  • Figure 5 illustrates a graph representing information transmitted by three users according to a third variant of the CDMA technique, in which the computer method for generation of the pseudo-orthogonal codes according to the invention is used;
  • Figure 6 represents the structure of a packet according to version 4 of the Internet protocol (IPv4); the pseudo-orthogonal code according to the invention is suitable for being generated starting from such packets; and
  • IPv4 Internet protocol
  • Figure 7 represents the structure of the header of a packet according to version 6 of the Internet protocol (IPv6); the pseudo-orthogonal code according to the invention is suitable for being generated starting from such packets.
  • IPv6 Internet protocol
  • each bit of information b(t) is multiplied by a binary sequence c(t), referred to as band-spreading code, which characterizes the user in question and is orthogonal to the codes used by the other users.
  • Figure 1 illustrates said multiplication.
  • said band increase is defined via a factor referred to as process gain, which is equal to the ratio between the rate f c of the signal transmitted and the rate f b of the information signal and is, in general, designated by "G":
  • the band-spreading code can be formed by the product, bit by bit, of the Walsh-Hadamard codes with pseudo-random sequences.
  • the second access technique, the TH-CDMA is also promising for future generations of mobile-radio systems.
  • This technique, also referred to as (IR) impulse radio is a spread-spectrum technique that uses pulses of extremely short duration of a pulse-position-modulation (PPM) type.
  • PPM pulse-position-modulation
  • N s is the number of pulses per bit
  • T b N S -T f is the bit duration.
  • the sequence ⁇ represents the bits of information.
  • An additional delay of c ⁇ T c is given by the TH code, with Q ⁇ C j ⁇ N h and
  • Figure 2 illustrates the concept of the TH-CDMA in the case of just one user who transmits one bit.
  • the TH codes used are a string of integers between 0 and (N h -1 ) of length N p .
  • the third access technique of a CDMA type is the FH-CDMA.
  • the total band is divided into a number of sub-bands, and each user transmits in one sub- band, which changes at pre-set time intervals according to a frequency-hopping (FH) sequence.
  • Figure 4 illustrates the FH-CDMA with just one user. In this example, the frequency-hopping sequence used [f2 f1 f1 f3] is illustrated.
  • Figure 5 illustrates multiple access with three users, in which user number 1 uses the sequence [f2 f1 f1 f3], user number 2 uses [f1 f2 f3 f1], and user number 3 uses [f3 f3 f2 f2]. If an integer is associated to each frequency, the FH codes are strings of integers.
  • Underlying the invention is the definition of an algorithm that enables a pseudo- random code to be obtained starting from a binary string.
  • the pseudo-random code is used for spread-spectrum access to a shared resource, typically the radio channel or cable channel.
  • a shared resource typically the radio channel or cable channel.
  • said code distinguishes the communication between two users of the network.
  • IP Internet Protocol
  • IPv4 Internet Protocol
  • An increasingly wide diffusion of this protocol is forecast for the next few years, together with a gradual migration to version 6 of the IP protocol, IPv6, on account of the limited number of Internet addresses that can be handled with IPv4.
  • IPv6 Internet Protocol
  • the algorithm according to the invention is designed to be applied to any binary string.
  • a possible advantageous application is the one where the binary string is the concatenation of the IP addresses of the source machine and of the addressee.
  • communication between two network nodes via IP is based upon the exchange of packets, referred to as IP packets, consisting of a header and a body.
  • IP packets consisting of a header and a body.
  • the structure of the header of the IPv4 packets is the one represented in Figure 6, and the structure of the header of the IPv6 packets is the one represented in Figure 7.
  • the length of said addresses is 32 bits for IPv4 and 128 bits for IPv6.
  • the length of the string for the generation of the code is 64 bits for IPv4 and 256 bits for IPv6.
  • the algorithm for generating the code which is designed to be used for the generation of the sequences in the three CDMA variants described above, is obtained with the following process. a) The string from which to start, of length L s , is defined. b) An integer k, with l ⁇ k ⁇ L s , ⁇ s extracted.
  • N b of bits is considered, which are set in the string in a position subsequent to the k-th bit, where N is derived by calculation of log 2 (N h ), and the value of all the N b bits, considered one after another, read in decimal base, constitutes the first element of the code word.
  • N h log 2
  • All the other N p elements of the code word are obtained by translating one bit to the right and repeating step c). Note that the numbers making up the output code are integers that may range from 0 to (Nh -1).
  • the inventive idea is linked to the possibility of generating a code with pseudorandom characteristics starting from a known binary string and an integer k.
  • the computer just has to store the binary string present in the software that implements the particular network protocol, for example the IP protocol in the case of communication via the Internet, and the integer k. This may be extracted from a generator of pseudorandom numbers present in the computer and stored for use in relation to the communication, or else it is possible to define the integer k in some other appropriate way.
  • the use of the invention is extremely wide because is applicable in all network terminals that use the spread-spectrum access technique to a shared resource, when the code used for the spread spectrum is a pseudo-random code.
  • the wide use of the IP and the diffusion of mobile-radio networks supporting IP with CDMA access to the radio resource renders the algorithm applicable to an extremely wide range of mobile networks for telecommunications.
  • the implementation of the method according to the invention is advantageously provided via the definition of a computer program, in particular for a general purpose computer, also of a personal-computer type.
  • the program may be written in an appropriate programming language, such as may be "C+" or equivalent.
  • the said program can be stored in data-processing means integrated directly with telecommunications devices and be implemented, according to appropriate modalities known to a person skilled in the branch, for the needs of data transmission.

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Mobile Radio Communication Systems (AREA)
  • Compression, Expansion, Code Conversion, And Decoders (AREA)

Abstract

L'invention concerne un procédé de génération de codes pseudo-orthogonaux destiné à une transmission de données par la technique CDMA. Ce procédé consiste a) à définir la valeur LS, correspondant à la longueur de la chaîne de laquelle on commence ; b) à extraire un nombre entier k, sachant que 1</= k </= Ls ; c) à prendre en considération, à partir du k ième bit de la chaîne, un nombre Nb de bits réglé dans la chaîne dans une position consécutive au kième bit, sachant que Nb = log2(Nh), et la valeur de tous les Nb considérés l'un après l'autre lu dans le système décimal constitue le premier élément du mot code. Les éléments du mot code sont des nombres entiers entre 0 et (Nh-1) ; et d) tous les autres éléments du mot code sont obtenus par déplacement d'un bit vers la droite et on répète l'opération c).
PCT/IB2002/004017 2001-09-28 2002-09-27 Procede informatique de generation de codes pseudo-orthogonaux destine a la transmission de donnees WO2003030425A2 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU2002338187A AU2002338187A1 (en) 2001-09-28 2002-09-27 Method for generating pseudo-orthogonal sequences

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
IT2001RM000592A ITRM20010592A1 (it) 2001-09-28 2001-09-28 Metodo informatizzato di generazione di codici pseudo-ortogonali.
ITRM2001A000592 2001-09-28

Publications (2)

Publication Number Publication Date
WO2003030425A2 true WO2003030425A2 (fr) 2003-04-10
WO2003030425A3 WO2003030425A3 (fr) 2003-10-23

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PCT/IB2002/004017 WO2003030425A2 (fr) 2001-09-28 2002-09-27 Procede informatique de generation de codes pseudo-orthogonaux destine a la transmission de donnees

Country Status (3)

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AU (1) AU2002338187A1 (fr)
IT (1) ITRM20010592A1 (fr)
WO (1) WO2003030425A2 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102265539A (zh) * 2011-04-28 2011-11-30 华为技术有限公司 生成准正交序列集的超集的方法

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19755832A1 (de) * 1997-12-16 1999-06-17 Cit Alcatel Verfahren zur Erzeugung einer Frequenzsprungfolge mittels verketteter Kodierungen, Funkvorrichtung und Funkkombinationssystem dafür

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102265539A (zh) * 2011-04-28 2011-11-30 华为技术有限公司 生成准正交序列集的超集的方法
US9407401B2 (en) 2011-04-28 2016-08-02 Huawei Technologies Co., Ltd. Method for generating a superset of quasi-orthogonal sets of sequences

Also Published As

Publication number Publication date
ITRM20010592A0 (it) 2001-09-28
ITRM20010592A1 (it) 2003-03-28
AU2002338187A1 (en) 2003-04-14
WO2003030425A3 (fr) 2003-10-23

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