GB2125654A - Intranetwork code division multiple access communication system - Google Patents
Intranetwork code division multiple access communication system Download PDFInfo
- Publication number
- GB2125654A GB2125654A GB08308603A GB8308603A GB2125654A GB 2125654 A GB2125654 A GB 2125654A GB 08308603 A GB08308603 A GB 08308603A GB 8308603 A GB8308603 A GB 8308603A GB 2125654 A GB2125654 A GB 2125654A
- Authority
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- United Kingdom
- Prior art keywords
- signal
- code
- digital
- digital data
- code word
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Classifications
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04J—MULTIPLEX COMMUNICATION
- H04J13/00—Code division multiplex systems
- H04J13/16—Code allocation
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04J—MULTIPLEX COMMUNICATION
- H04J13/00—Code division multiplex systems
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- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Mobile Radio Communication Systems (AREA)
Abstract
A CDMA format is used within a network to permit communication between members of the network. A predetermined set of digital code words is established for the network. A member desiring to transmit digital data selects an unused code word. A CDMA generator generates a reference code corresponding to the selected unused code word. The code word is gated with a signal from a pseudo-random noise generator, the output of which is then gated with the digital data to be transmitted to form a digital signal. A carrier signal is modulated with the digital signal and transmitted. The transmitted digital data modulating the carrier signal is demodulated to provide a digital signal. The particular code word embodied in the digital signal is determined by a corresponding PN generator and a corresponding CDMA generator which provides outputs which are gated and mixed with the digital signal resulting in the digital data being separated from the digital signal. <IMAGE>
Description
SPECIFICATION
Intranetwork code division multiple access communication system
The invention relates generally to communication systems and, in particular, to communication systems employing code division multiple access.
Code division multiple access communication systems are well known in the prior art. Such systems assign codes to users according to a demand access (or floating assignment) priority or may use pre-assigned codes. In the former case, assignments of codes may be controlled or selfselecting (autonomous) controlled assignments which tend to limit the system operating parameters.
Self-selecting code systems require a networkcontrolled master to monitor the selection process.
In the latter case of a multiple member network in which two or three members may be simultaneously communicating, preassigning of codes becomes very complex and is a limiting factor in the number of members which can be a part of the network.
It is an object of this invention to provide a communication system employing code division multiple access (CDMA) in a floating assignment or demand access mode.
It is another object of this invention to provide a
CDMA communication system which self-selects codes without a network-controlled master.
The invention includes an apparatus for transmitting digital data within a network. An unused code word is selected from a predetermined set of code words within the network. A reference code corresponding to the selected unused code word is generated and the digital data to be transmitted is gated with the selected code word thereby forming a digital signal. A carrier signal is modulated with the digital signal and the modulated carrier signal is transmitted.
The transmitted digital data is detected and the carrier signal is demodulated from the detected signal to provide the digital signal. The code word embodied in the digital signal is determined from the available code words and the digital data is separated from the code word embodied in the digital signal.
For a better understanding of the present invention, together with other and further objects, reference is made to the following description, taken in conjunction with the accompanying drawings, and its scope will be pointed out in the appended ciaims.
Figure 1 is a block diagram illustrating a transmitter according to the invention.
Figure 2 is a block diagram illustrating a receiver according to the invention.
The invention relates generally to the transmission of digital data. The digital data to be transmitted may be provided by any source and is referred to in
Figure 1 as coded data transmitted via line 6. As illustrated in Figure 1, the coded data on line 6 may be the result of audio information which is applied to audio encoder 7, the output of which is applied to data encoder 8. Audio encoder 7 may be any prior art system for digitally encoding audio information such as a continuously variable slope delta-modulated key (CVSK) system. The data output of audio encoder 7 may be digitally encoded by a differential binary encoder or any other digital encoder known in the prior art. Audio encoder 7 and data encoder 8 form a means for providing the digital data to be transmitted as coded data 6.
In pre-assigned CDMA systems, each member of a network is normally provided with a code. However, usually only a few (two or three) members are communicating at any given time and it is only necessary for codes to be assigned to those members which are communicating. When the number of members in a given network is large, preassigning each member a different code becomes a complex problem since each member must be able to detect the codes of all other members of the same network.
In demand access CDMA, a control or master for each network is required to monitor code assignments. The need for a control monitor is an unnecessary limit on the system.
The present invention minimizes these problems by predetermining a set of code words which are used by a given network and permits each memeber to select its own word. This set of code words is sufficiently large to avoid detection and deciphering.
The actual number of code words in the set is based on the anticipated number of members which would be communicating during a given period of time and the security desired. For example, when only two members are likely to be communicating within a network at any given time, twenty codes may be used to define the predetermined set.
Rather than preassigning code words to each member, the invention employs floating assignment or demand access of the code words without the need for a control monitor. Each member is familiar with the set of, for example, thirty code words and continuously monitors the use of the code words within the network. When a network member desires to transmit digital data, a push-to-talk (PTT) request is provided to a means for selecting an unused code word from the predetermined set of code words.
Such a means may be a selector referred to by reference character 2. Monitor 2B monitors the codes stored in means 2A which includes a memory and a pseudo-random generator which randomly selects the available codes for monitoring. Monitor 2B segregates all code words which are not being used. An algorithm defined in processor 2C selects a code word from the unused code words which are available at a particular time and verifies through monitor 2B that the code word is available. More than one code word may be selected and searched for verification depending on the algorithm being employed. When a code word is verified as avaiiable, processor 2C assigns the code word to the network member and provides a reference code to
CDMA generator 3. The reference code corresponds to the unused code word that has been selected and causes generator 3 to generate the particular code word.This code word is gated by gating means 4 with an output signal from pseudo-random noise generator 5, the output of which is then gated with coded data 6. Gating means 4 may be any logic gating circuitry for achieving a desired overlaying of information such as exclusive OR gates 9 and 10.
The output of gating means 10 is provided to mixer 11 along with an IF signal on which the data is modulated, the output of which is provided to a radio frequency modulator 12 which modulates a local oscillator carrier signal with the information provided at the output of mixer 11. The modulated carrier is then transmitted by antenna 13.
Figure 2 illustrates a receiver according to the invention. Similar reference characters are used for similar structure. In a receiver/transmitter unit used by a member of the network, such similar structure may be a single item which functions in both the transmit and receive modes. As shown in Figure 2,
RF receiver 22 receives the information on the carrier signal received by antenna 13. The received information is applied to mixer 11 along with the local oscillator carrier signal LO to provide an IF signal including a digital signal. This is applied to mixer 14 along with the output from means 30 for determining, from the available code words, the code word which is embodied in the digital signal. The output of mixer 14 provides coded data to means 40 for separating and decoding the digital data from the code word embodied in the digital signal.Data decoder 41 determines the data within the coded data signal and provides the data to audio decoder 41 for providing the audio signal from data.
Means 30 includes acquisition microprocessor 15 which is used to control CDMA generator 3 and delays 16 and 17. Means 2 provides a signal to
CDMA generator 3 which represents one of the available codes at a particular point in time. Processor 15 gates this code with PN generator output 18 through exclusive OR gate 19. The output of OR gate
19 is provided to matched filter 21 along with the output of mixer 11. Matched filter 21 is a programmable matched filter which is controlled by processor
15 to be matched to each of the codes of the
predetermined set of code words. When the code word in the message is matched to filter 21,
processor 15 instructs generator 3 to duplicate this code word. The delayed PN generator output 18 and
CDMA generator output are suitably delayed and
gated by gate 19 and mixed with the IF signal by
mixer 20. The output of mixer 20 is then mixed with the digital IF signal by mixer 14. This results in mixer
14 providing coded data to decoders 41 and 42.
Claims (14)
1. An apparatus for transmitting digital data
within a network comprising:
first means (1) for providing the digital data to be transmitted;
second means (2) for selecting, from a predeter
mined set of code words within the network, an
unused code word;
third means (3) for generating a reference code
corresponding to the unused code word selected by the second means;
fourth means (4) for gating the digital data and a
particular code word corresponding to said refer
ence code to form a digital signal;
fifth means (11) for modulating a carrier signal with the digital signal; and
sixth means (12) for transmitting the modulated carrier signal.
2. The apparatus of claim 1 further comprising a pseudo-random noise (PN) generator (5) supplying a
PN signal and wherein said fourth means gates the
PN signal with the digital data and the reference code to form a digital signal.
3. The apparatus of claim 2 wherein said first means comprises an audio encoding means having an input for receiving the audio information and having an output for providing digital data corresponding to said audio information.
4. The apparatus of claim 3 wherein said first means further comprises a data encoder with an input for receiving the digital data and an output for providing coded digital data corresponding to the digital data.
5. The apparatus of claim 1 wherein said second means comprises means for randomly selecting available codes, means for searching and verifying that the selected codes are available and means for assigning a code division multiple access (CDMA) code.
6. The apparatus of claim 5 wherein said third means comprises a CDMA generator.
7. The apparatus of claim 6 wherein said fourth means comprises at least one exclusive OR gate.
8. The apparatus of claim 7 wherein said fifth means and said sixth means comprise an RF modulator and transmitter.
9. An apparatus for receiving a signal comprising a particular code word and digital data modulating a carrier signal comprising:
first means (13) for detecting the signal;
second means (22, 11) for demodulating the carrier signal from the detected signal and for providing a digital signal including the particular code word and the digital data;
third means (2) for determining, from a predetermined set of code words, the available code words;
fourth means (30) for determining, from the available code words, the particular code word included in the digital signal; and
fifth means (40) for separating the digital data from the particular code word included in the digital signal.
10. The apparatus of claim 9 wherein said fourth means comprises a pseudo-random noise (PN) generator supplying a PN signal;
a CDMA generator for generating a reference code corresponding to one of the unused codes;
means for gating the PN signal and the reference code to form a digital reference signal; and
means for mixing the digital reference signal and the digital signal and providing the transmitted digital data.
11. An apparatus comprising:
a transmitter comprising first means for providing digital data to be transmitted within a network;
second means for selecting, from a predetermined set of code words within the network, an unused code word;
third means for generating a reference code corresponding to the unused code word selected by the second means;
fourth means for gating the digital data and a particular code word corresponding to said reference code to form a digital signal;
fifth means for modulating a carrier signal with the digital signal; and
sixth means for transmitting the modulated carrier signal;
and a receiver comprising seventh means for detecting the modulated carrier signal;
eighth means for demodulating the carrier signal from the detected modulated carrier signal and for providing a digital signal including the particlar code word and the digital data modulating the carrier signal;
ninth means for determining, from a predetermined set of code words, the available code words;
tenth means for determining, from the available code words, a code word embodied in the digital signal; and
eleventh means for separating the digital data from the code word embodied in the digital signal.
12. Apparatus according to claim 1 and substantially as described herein with reference to Figure 1 of the accompanying drawing.
13. Apparatus according to claim 9 and substantially as described herein with reference to Figure 2 of the accompanying drawing.
14. An intranetworkcode division multiple access communication system substantially as described herein with reference to the accompanying drawing.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US40798082A | 1982-08-13 | 1982-08-13 |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB8308603D0 GB8308603D0 (en) | 1983-05-05 |
| GB2125654A true GB2125654A (en) | 1984-03-07 |
| GB2125654B GB2125654B (en) | 1986-01-29 |
Family
ID=23614352
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB08308603A Expired GB2125654B (en) | 1982-08-13 | 1983-03-29 | Intranetwork code division multiple access communication system |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2125654B (en) |
Cited By (15)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2172777A (en) * | 1985-03-21 | 1986-09-24 | Hazeltine Corp | Code division multiple access communication system |
| WO1987004883A1 (en) * | 1986-02-04 | 1987-08-13 | Advanced Systems Research Pty. Ltd. | Spread-spectrum multiplexed transmission system |
| EP0240124A2 (en) * | 1986-02-28 | 1987-10-07 | AT&T Corp. | Lightwave communication system |
| EP0257110A1 (en) * | 1986-08-14 | 1988-03-02 | Alcatel SEL Aktiengesellschaft | Digital cellular system |
| US4901307A (en) * | 1986-10-17 | 1990-02-13 | Qualcomm, Inc. | Spread spectrum multiple access communication system using satellite or terrestrial repeaters |
| US4912722A (en) * | 1988-09-20 | 1990-03-27 | At&T Bell Laboratories | Self-synchronous spread spectrum transmitter/receiver |
| EP0629325A1 (en) * | 1992-03-05 | 1994-12-21 | Qualcomm Incorporated | Apparatus and method for reducing message collision between mobile stations simultaneously accessing a base station in a cdma cellular communications system |
| WO1996005668A1 (en) * | 1994-08-16 | 1996-02-22 | Ericsson, Inc. | Multiple access coding using bent sequences for mobile radio communications |
| US5715236A (en) * | 1990-06-25 | 1998-02-03 | Qualcomm Incorporated | System and method for generating signal waveforms in a CDMA cellular telephone system |
| GB2319930A (en) * | 1996-11-27 | 1998-06-03 | Sony Uk Ltd | Storage and transmission of one-bit data |
| GB2338157A (en) * | 1998-04-04 | 1999-12-08 | Samsung Electronics Co Ltd | Spread spectrum signal generating device utilising a selected one of a plurality of different spreading techniques. |
| EP1231804A1 (en) * | 2001-02-07 | 2002-08-14 | Siemens Aktiengesellschaft | Method and device for allocating a code in a CDMA communications system |
| WO2002063908A1 (en) * | 2001-02-07 | 2002-08-15 | Siemens Aktiengesellschaft | Method and communication device for assigning a code in a cdma communication system |
| US6618429B2 (en) | 1990-06-25 | 2003-09-09 | Oualcomm Incorporated | System and method for generating signal waveforms in a CDMA cellular telephone system |
| US8213485B2 (en) | 1996-05-28 | 2012-07-03 | Qualcomm Incorporated | High rate CDMA wireless communication system using variable sized channel codes |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4675863A (en) | 1985-03-20 | 1987-06-23 | International Mobile Machines Corp. | Subscriber RF telephone system for providing multiple speech and/or data signals simultaneously over either a single or a plurality of RF channels |
| US5546383A (en) | 1993-09-30 | 1996-08-13 | Cooley; David M. | Modularly clustered radiotelephone system |
| US5926500A (en) | 1996-05-28 | 1999-07-20 | Qualcomm Incorporated | Reduced peak-to-average transmit power high data rate CDMA wireless communication system |
-
1983
- 1983-03-29 GB GB08308603A patent/GB2125654B/en not_active Expired
Cited By (34)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2172777A (en) * | 1985-03-21 | 1986-09-24 | Hazeltine Corp | Code division multiple access communication system |
| AU582038B2 (en) * | 1986-02-04 | 1989-03-09 | British Aerospace Australia Limited | Spread-spectrum multiplexed transmission system |
| WO1987004883A1 (en) * | 1986-02-04 | 1987-08-13 | Advanced Systems Research Pty. Ltd. | Spread-spectrum multiplexed transmission system |
| EP0240124A3 (en) * | 1986-02-28 | 1990-10-24 | American Telephone And Telegraph Company | Lightwave communication system |
| US4703474A (en) * | 1986-02-28 | 1987-10-27 | American Telephone And Telegraph Company, At&T Bell Laboratories | Spread spectrum code-division-multiple-access (SS-CDMA) lightwave communication system |
| EP0240124A2 (en) * | 1986-02-28 | 1987-10-07 | AT&T Corp. | Lightwave communication system |
| EP0257110A1 (en) * | 1986-08-14 | 1988-03-02 | Alcatel SEL Aktiengesellschaft | Digital cellular system |
| AU591575B2 (en) * | 1986-08-14 | 1989-12-07 | Alcatel N.V. | Cellular radio system |
| US4901307A (en) * | 1986-10-17 | 1990-02-13 | Qualcomm, Inc. | Spread spectrum multiple access communication system using satellite or terrestrial repeaters |
| US4912722A (en) * | 1988-09-20 | 1990-03-27 | At&T Bell Laboratories | Self-synchronous spread spectrum transmitter/receiver |
| US7839960B2 (en) | 1990-06-25 | 2010-11-23 | Qualcomm Incorporated | System and method for generating signal waveforms in a CDMA cellular telephone system |
| US6693951B1 (en) | 1990-06-25 | 2004-02-17 | Qualcomm Incorporated | System and method for generating signal waveforms in a CDMA cellular telephone system |
| US6618429B2 (en) | 1990-06-25 | 2003-09-09 | Oualcomm Incorporated | System and method for generating signal waveforms in a CDMA cellular telephone system |
| US5715236A (en) * | 1990-06-25 | 1998-02-03 | Qualcomm Incorporated | System and method for generating signal waveforms in a CDMA cellular telephone system |
| US7734260B2 (en) | 1992-03-05 | 2010-06-08 | Qualcomm Incorporated | Apparatus and method for reducing message collision between mobile stations simultaneously accessing a base station in a CDMA cellular communications system |
| EP0629325A4 (en) * | 1992-03-05 | 1998-04-08 | Qualcomm Inc | Apparatus and method for reducing message collision between mobile stations simultaneously accessing a base station in a cdma cellular communications system. |
| EP1746795A3 (en) * | 1992-03-05 | 2007-05-23 | Qualcomm, Incorporated | Apparatus and method for reducing message collision between mobile stations simultaneously accessing a base station in a CDMA cellular communications system |
| EP2058994A1 (en) * | 1992-03-05 | 2009-05-13 | Qualcomm Incorporated | Apparatus and method for reducing message collision between mobile stations simultaneously accessing a base station in a CDMA cellular communications system |
| US7426391B2 (en) | 1992-03-05 | 2008-09-16 | Qualcomm Incorporated | Apparatus and method for reducing message collision between mobile stations simultaneously accessing a base station in a CDMA cellular communications system |
| EP1583309A2 (en) * | 1992-03-05 | 2005-10-05 | Qualcomm, Incorporated | Apparatus and method for reducing message collision between mobile stations simultaneously accessing a base station in a CDMA cellular communications system |
| EP0629325A1 (en) * | 1992-03-05 | 1994-12-21 | Qualcomm Incorporated | Apparatus and method for reducing message collision between mobile stations simultaneously accessing a base station in a cdma cellular communications system |
| EP1583309A3 (en) * | 1992-03-05 | 2006-03-01 | Qualcomm, Incorporated | Apparatus and method for reducing message collision between mobile stations simultaneously accessing a base station in a CDMA cellular communications system |
| EP1746795A2 (en) * | 1992-03-05 | 2007-01-24 | Qualcomm, Incorporated | Apparatus and method for reducing message collision between mobile stations simultaneously accessing a base station in a CDMA cellular communications system |
| US5550809A (en) * | 1992-04-10 | 1996-08-27 | Ericsson Ge Mobile Communications, Inc. | Multiple access coding using bent sequences for mobile radio communications |
| WO1996005668A1 (en) * | 1994-08-16 | 1996-02-22 | Ericsson, Inc. | Multiple access coding using bent sequences for mobile radio communications |
| US8588277B2 (en) | 1996-05-28 | 2013-11-19 | Qualcomm Incorporated | High data rate CDMA wireless communication system using variable sized channel codes |
| US8213485B2 (en) | 1996-05-28 | 2012-07-03 | Qualcomm Incorporated | High rate CDMA wireless communication system using variable sized channel codes |
| US6970753B2 (en) | 1996-11-27 | 2005-11-29 | Sony Corporation | Storage and transmission of one-bit data |
| GB2319930B (en) * | 1996-11-27 | 2001-05-16 | Sony Uk Ltd | Storage and transmission of one-bit data |
| GB2319930A (en) * | 1996-11-27 | 1998-06-03 | Sony Uk Ltd | Storage and transmission of one-bit data |
| GB2338157B (en) * | 1998-04-04 | 2002-11-20 | Samsung Electronics Co Ltd | Spread spectrum signal generating device for a spread spectrum communication system |
| GB2338157A (en) * | 1998-04-04 | 1999-12-08 | Samsung Electronics Co Ltd | Spread spectrum signal generating device utilising a selected one of a plurality of different spreading techniques. |
| WO2002063908A1 (en) * | 2001-02-07 | 2002-08-15 | Siemens Aktiengesellschaft | Method and communication device for assigning a code in a cdma communication system |
| EP1231804A1 (en) * | 2001-02-07 | 2002-08-14 | Siemens Aktiengesellschaft | Method and device for allocating a code in a CDMA communications system |
Also Published As
| Publication number | Publication date |
|---|---|
| GB2125654B (en) | 1986-01-29 |
| GB8308603D0 (en) | 1983-05-05 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |