Coder-packetizer for random accessing in digital communication with multiple accessing

• US 4,761,778 A
• Filed: 04/11/1985
• Issued: 08/02/1988
• Est. Priority Date: 04/11/1985
• Status: Expired due to Fees

• Current Assignee: Massachusetts Institute of Technology
• Original Assignee: Massachusetts Institute of Technology
• Inventors: Hui, Joseph Y. N.
• Primary Examiner(s): Olms, Douglas W.
• Assistant Examiner(s): Scutch, III, Frank M.
• Application Number:
  US06/722,275
• Time in Patent Office: 1,209 Days
• Field of Search: 370/85, 370/94, 370/60, 370/99, 370/89, 370/109, 370/104, 370/46, 371/45, 371/46
• US Class Current: 370/441
• CPC Class Codes: H04L 1/0059 Convolutional codes
• CPC Class Codes: H04L 1/0071 Use of interleaving interleaving per se H03M13/27
• CPC Class Codes: H04W 74/08 Non-scheduled access, e.g. ALOHA hybrid access H04W74/02

Abstract

A Coded Data Multiple Access (CDMA) communication system in which a bit stream of digitized data is convolutionally encoded, and interleaved, to provide time diversity for consecutive output bits of the encoder. The interleaved encoded message is packetized into blocks to which synchronization and user identity preambles are provided. Each packet is transmitted in time compressed bursts at random time intervals.

Claims

1. In a common channel of communication, apparatus for transmitting serially related bit streams of information from multiple geographically distributed sources over said common channel of communications, comprising:

(a) an encoder for at least one such source for redundantly encoding the bits in a bit stream originating from said one such source into a serially related encoded bit stream;

(b) interleaving means for interleaving the bits into a plurality of different packets of bits;

(c) storage means for storing said packets;

(d) transmitter means for transmitting said packets in bursts at random intervals over said common channel;

the number of such packets being sufficiently large so that consecutive bits in a packet are not serially related.

2. The apparatus of claim 1 wherein a randomizer means enables the transmitter means to transmit the packets at said random intervals.

3. The apparatus of claim 1 wherein the encoder is a convolutional encoder.

4. Apparatus for transmitting serially related bit streams of information from multiple geographically distributed sources over a common channel of communications, comprising for each such source:

(a) a convolutional encoder having a code sequence for redundantly encoding the bits in a sequence of bits originating at a respective source into an output symbol sequence of serially related encoded bits which is the convolution of the bit sequence with the code generation sequence;

(b) switching means for interleaving the encoded bits into different packets, the number of such packets being sufficiently large so that consecutive bits in each packet are not serially related;

(c) transmitter means for transmitting said packets sequentially in a compressed time frame and at random intervals over said common channel.

5. A coded data multiple access transmitter system for transmitting bit streams of information from multiple sources geographically separated over a common channel of communications, comprising:

(a) a convolutional encoder for redundantly encoding the bits in a bit stream originating from at least one such source to provide an encoded bit stream of consecutive serially related bits which is the moving weighted sum of the input bit stream;

(b) interleaving means for interleaving the encoded bit stream into stacks of packets of predetermined bit length;

the number of such packets being sufficient to assure that consecutive bits in each packet are not serially related;

(c) preamble means for providing user identity and preamble bits onto said packets; and

(d) transmitter means for transmitting said packets sequentially in a relatively short time period and at random intervals over said common channel.

6. The system of claim 5 wherein the number of packets is at least equal to k times v wherein k=the number of bits in a register and v is the rate of the convolutional encoder in bits out per bits in.

7. A method of transmitting a digitized serially related bit stream of information from multiple sources located at geographically distributed locations over a common channel of communication comprising the steps of:

(a) redundantly encoding said information from at least one of said multiple sources into a stream of serially related encoded bits;

(b) interleaving and storing said encoded bits into a plurality of packets, each a plurality of bits in length;

the number of such packets being sufficiently large to prevent the occurrence in said packets of consecutive serially related bits;

(c) transmitting over said common channel said packets sequentially at intervals in a compressed time frame and at random intervals.

8. A method of of CDMA communication by transmitting digitized serially related bit streams of information from multiple geographically distributed sources over a common channel of communication comprising for each of said multiple sources the steps of:

(a) convolutionally encoding sets of information bits from a respective source to produce encoded sets of information bits;

(b) interleaving and storing said encoded information in a plurality of packets, each a plurality of bits in length; and

the number of packets is sufficiently large so that each bit in a packet originated from a different set of encoded information bits;

(c) providing synchronization and user identity preambles on said packets;

(d) transmitting said packets over said common channel sequentially at random time intervals and in a compressed time frame.