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• 1

  Patent

  Code time division Multiple Access System
  

  Inventor(s):

  James L. Massey

  Patent Number:

  EP 0486834B1

  Description:

  In a multiple access method for the simultaneous exchange of several data streams ({B.sub.1,m }, {B.sub.2,m }, {B.sub.3,m }) among several participants of a transmission system, various data streams ({B.sub.1,m }, {B.sub.2,m }, {B.sub.3,m }) with the same spread sequence (s[.]) are expanded to a corresponding DSSS signal ({B.sub.1,m s[.]}, {B.sub.2,m s[.]}, {B.sub.3,m s[.]}. During transmission, the various DSSS signals ({B.sub.1,m s[.]}, {B.sub.2,m s[.]}, {B.sub.3,m s[.]}) are heterodyned to…

  Date Issued:

  1990-11-22

  Record Visibility:

  Public

  Title

  Code time division Multiple Access System

  Description

  In a multiple access method for the simultaneous exchange of several data streams ({B.sub.1,m }, {B.sub.2,m }, {B.sub.3,m }) among several participants of a transmission system, various data streams ({B.sub.1,m }, {B.sub.2,m }, {B.sub.3,m }) with the same spread sequence (s[.]) are expanded to a corresponding DSSS signal ({B.sub.1,m s[.]}, {B.sub.2,m s[.]}, {B.sub.3,m s[.]}. During transmission, the various DSSS signals ({B.sub.1,m s[.]}, {B.sub.2,m s[.]}, {B.sub.3,m s[.]}) are heterodyned to a single incoming signal. For detecting the various data streams in a receiver, the incoming signal is filtered in a filter that is inverse with respect to the joint spread sequence (s[.]). In order to permit reliable detection, heterodyning takes place in each case so that the spread sequence intervals pertaining to different data streams are chronologically shifted with respect to one another by a given minimum value (delta.sub.-- T). The invention provides a multiple access method combining therein the advantages of TDMA and CDMA. In particular, an almost complete separation of the users is possible without requiring the precision of synchronization customary in case of TDMA.

  Creator

  James L. Massey

  Publisher

  European Patent Office

  Language

  German, English, French

  Resource Type

  Patent

• 2

  Patent

  Device for the conversion of a digital block and use of same 
  

  Inventor(s):

  James L. Massey, Xuejia Lai

  Patent Number:

  EP 0482154B1

  Description:

  The device (12) comprises nine coding stages (61.1, 61.2, 69), the first eight of which are of identical construction. It also comprises a coding partial block generation unit (63), an input unit (21) and an output unit (79). It is used for the blockwise coding of a plain text (X) from an information source (11) into a coded text (Y) to be taken to a transmission line (13), whereby a secret code block (Z) is previously introduced via a secure channel (17). Coding takes place stepwise and in p…

  Date Issued:

  1993-06-30

  Record Visibility:

  Public

  Title

  Device for the conversion of a digital block and use of same 

  Description

  The device (12) comprises nine coding stages (61.1, 61.2, 69), the first eight of which are of identical construction. It also comprises a coding partial block generation unit (63), an input unit (21) and an output unit (79). It is used for the blockwise coding of a plain text (X) from an information source (11) into a coded text (Y) to be taken to a transmission line (13), whereby a secret code block (Z) is previously introduced via a secure channel (17). Coding takes place stepwise and in parallel for four partial blocks (X1 - X4; W11 - W14; W21 - W24; W81 - W84; Y1 - Y4) at a time. To this end, each coding stage (61.1, 61.2, 60) has four first inputs (25 - 28; 35 - 38), six or four second inputs (29, 30, 32, 33, 49, 52; 129, 130, 132, 133) and four outputs (75 - 78).; At the second inputs there are a total of fifty-two coding partial blocks (Z1 - Z52) formed from the code block (Z). The device (12) may also be used unchanged for decoding an incoming cipher text (Y). For this purpose it is merely necessary to apply other code partial blocks to the second inputs.

  Creator

  James L. Massey, Xuejia Lai

  Publisher

  European Patent Office

  Language

  German, English, French

  Resource Type

  Patent