Apparatus and method for transmitting digital data over a radio communications channel

• US 4,905,234 A
• Filed: 06/03/1987
• Issued: 02/27/1990
• Est. Priority Date: 06/03/1987
• Status: Expired due to Term

• Current Assignee: Ericsson, Inc. (Telefonaktiebolaget LM Ericsson)
• Original Assignee: General Electric Company
• Inventors: Hughes, Houston H. III, Childress, Jeffrey S., Hall, Nancy L.
• Primary Examiner(s): Orsino, Joseph A.
• Assistant Examiner(s): NOT, DEFINED
• Application Number:
  US07/056,923
• Time in Patent Office: 1,000 Days
• Field of Search: 370/60, 370/94, 370/89, 370/95, 370/110.1, 455/63, 455/67, 371/33, 371/32
• US Class Current: 370/349
• CPC Class Codes: H04L 1/08 by repeating transmission, e.g. Verdan system H04L1/1858 and H04L1/189 take precedence
• CPC Class Codes: H04L 1/1614 using bitmaps
• CPC Class Codes: H04L 1/1671 the supervisory signal being transmitted together with control information
• CPC Class Codes: H04L 1/188 Time-out mechanisms
• CPC Class Codes: H04L 1/189 Transmission or retransmission of more than one copy of a message
• CPC Class Codes: H04L 2001/125 Arrangements for preventing errors in the return channel
• CPC Class Codes: H04W 4/10 Push-to-Talk [PTT] or Push-On-Call services
• CPC Class Codes: H04W 76/45 for Push-to-Talk [PTT] or Push-to-Talk over cellular [PoC] services
• CPC Class Codes: H04W 84/08 Trunked mobile radio systems
• CPC Class Codes: Y10S 370/913 Wireless or radio

Abstract

A digital radio RF signalling protocol communicates either digitized voice or digital data signals and indicates the type of information being communicated to the receiver. Multiple repeats of control signals are provided for face protection and to ensure correct receipt even under adverse communications channel conditions. When the destination transceiver receives a transmitted digital data burst from the transmitter, the destination transceiver transmits a responsive acknowledge message and may specify in the acknowledge message which portions of the received message were received incorrectly and should be retransmitted by the originating transceiver. The originating transceiver determines the contents of subsequently-transmitted data burst based upon the information it receives from the destination transceiver by way of the acknowledge message. As deleterious phenomena (e.g., noise and/or fading) degrade communcations channel quality, the acknowledge message handshaking causes the originating transceiver to repeat incorrectly received data packets until the destination transceiver finally receives those data packets correctly.

Claims

1. A method for reliably and quickly exchanging bursts of digital data packets between a first site and a second site, said method comprising the steps of:

(a) transmitting a plurality N digital data packets from said first site to said second site;

(b) checking for the correct receipt of all N packets at said second site;

(c) transmitting a binary coded N-bit map of digital data from said second site back to said first site identifying any data packets not yet correctly received at said second site;

(d) retransmitting at least such identified data packets, if any, from said first site to said second site; and

(e) repeating said steps (b)-(d) until all N-packets have been correctly received at said second site.

17. A method as in claim 1 wherein said transmitting step (c) comprises transmitting a binary coded bit map comprising N bits corresponding to said N packets, a one-to-one correspondence existing between said N bits of said bit map and said N packets in the last transmitted data burst.

2. A method of transmitting digital signals from a data originating digital radio transceiver over a RF communication channel to a destination digital radio transceiver, said method comprising:

(a) transmitting, from said data originating transceiver to said destination transceiver over said RF channel, a plurality N of successive data packets in a first data burst;

(b) receiving said first data burst with said destination transceiver;

(c) determining at said destination transceiver which of said N data packets were correctly received by said destination transceiver and which of said data packets were incorrectly received by said destination transceiver and transmitting a bit map from said destination transceiver to said source transceiver specifying at least said incorrectly received, packets; and

(d) retransmitting, from said data originating transceiver to said destination transceiver, a further data burst including N successive data packets, said further data burst data packets including said incorrectly received data packets and no correctly received ones of said data packets of said first data burst.

3. A method as in claim 2 further including the step of transmitting an acknowledge message from said destination transceiver to said originating transceiver over said communication channel, said acknowledge message indicating which of said data packets within said first data burst were correctly received and which of said data packets within said first data burst were incorrectly received.

4. A method as in claim 2 wherein:

said method further includes the step of transmitting an acknowledge message from said destination transceiver to said originating transceiver over said communication channel in response to receipt of said first data burst by said destination transceiver, said acknowledge message including the results of said determining step; and

said retransmitting step includes the step of selecting data packets for retransmission in response to said acknowledge message.

18. A method as in claim 2 wherein said step (c) includes transmitting a binary coded bit map comprising N bits corresponding to said N packets, a one-to-one correspondence existing between said N bits of said bit map and said N packets in the last transmitted data burst.

5. A method of transmitting digital signals from a data originating digital radio transceiver over a RF communication channel to a destination digital radio transceiver, said method comprising:

(a) transmitting, from said data originating transceiver to said destination transceiver over said RF channel, a plurality N of successive data packets in a first data burst;

(b) receiving said first data burst with said destination transceiver;

(c) determining at said destination transceiver which of said N data packets were correctly received by said destination transceiver and which of said data packets were incorrectly received by said destination transceiver and transmitting a bit map from said destination transceiver to said source transceiver specifying at least said incorrectly received packets; and

(d) retransmitting from said data originating transceiver to said destination transceiver, a further data burst including N successive data packets, said further data burst data packets including said incorrectly received data packets and no correctly received ones of said first data burst data packets,

wherein said retransmitting step includes retransmitting each of said incorrectly received data packets plural times, none of said incorrectly received data packets being retransmitted more than one time more than any other of said incorrectly received data packets is retransmitted.

19. A method as in claim 5 wherein said step (c) includes transmitting a binary coded bit map comprising N bits corresponding to said N packets, a one-to-one correspondence existing between said N bits of said bit map and said N packets in the last transmitted data burst.

6. A method of transmitting digital signals from a data originating digital radio transceiver over a RF communication channel to a destination digital radio transceiver, said method comprising:

(a) transmitting, from said data originating transceiver to said destination transceiver over said RF channel, a plurality N of successive data packets in a first data burst;

(b) receiving said first data burst with said destination transceiver;

(c) determining at said destination transceiver which of said N data packets were correctly received by said destination transceiver and which of said data packets were incorrectly received by said destination transceiver and transmitting a bit map from said destination transceiver to said source transceiver specifying at least said incorrectly received packets; and

(d) retransmitting, from said data originating transceiver to said destination transceiver, a further data burst including N successive data packets, said further data burst data packets including said incorrectly received data packets and no correctly received ones of said first data burst data packets,

wherein;

said method further includes the step of transmitting an acknowledge message from said destination transceiver t aid originating transceiver over said communication channel in response to receipt of said first data burst by said destination transceiver, said acknowledge message including signals indicating the results of said determining step; and

said retransmitting step includes the step of selecting data packets for retransmission in response to said acknowledge message and retransmitting each of said selected data packets multiple times x until N data packets have been transmitted in said further data burst, none of said selected data packets being transmitted more than x+1 times.

20. A method as in claim 6 wherein said step (c) includes transmitting a binary coded bit map comprising N bits corresponding to said N packets, a one-to-one correspondence existing between said N bits of said bit map and said N packets in the last transmitted data burst.

7. A method of transmitting digital signals from a data originating digital radio transceiver over a RF communication channel to a destination digital radio transceiver, said method comprising:

(a) transmitting, from said data originating transceiver to said destination transceiver over said RF channel, a plurality N of successive data packets P(1)-P(N) in a first data burst;

(b) receiving said first data burst with said destination transceiver;

(c) determining which of said data packets P(1)-P(N) were correctly received by said destination transceiver and which of said data packets were incorrectly received by said destination transceiver;

(d) storing said correctly received data packets into a buffer capable of storing a maximum of Q data packets;

(e) calculating the number X of new packets P(N+1) - P(Q) which can be stored in said buffer while reserving space in said buffer for said incorrectly received data packets;

(f) transmitting an acknowledge message from said destination transceiver to said data originating transceiver, said acknowledge message indicating the data packets which were incorrectly received by said destination transceiver and the number of new packets said buffer can store in addition to said incorrectly received data packets; and

(g) retransmitting, from said data originating transceiver to said destination transceiver, a further data burst including said incorrectly received data packets and said number X of new data packets, said incorrectly received data packets being repeated in sequence until the number of data packets in said further data burst totals N, none of said data packets within said further data burst being repeated more than one time more than any other data packet within said further data burst.

8. A transceiver for sending and receiving digital control and digital data signals over a communication channel, said transceiver comprising:

transmitter and receiver means for transmitting and/or receiving a succession of digital signals; and

control means connected to said transmitter and receiver means and including a digital data microprocessor system programmed so as to control said transmitter and receiver means to process said digital signals occurring in substantially the following time sequence;

(a) a preamble portion having;

(1) an alternating 1,0 dotting pattern,

(2) Twelve repeated sets of

(i) a 16 bit synchronization word S including a multiple bit Barker code,

(ii) a 16 bit outside address word OA including a multiple bit sequence repeated at least once, said outside address word indicating whether a later-processed string of digital data includes digitized voice signals or other types of digital signals,

(iii) a 16 bit sync number code (identifying which of 12 repeats is involved),

(3) Nine repeated sets of

(i) a 64 bit guard band,

(ii) a 64 bit cryptographic initialization vector,

(iii) a 16 bit selective signalling code identifying the intended message recipient(s),

(b) a plurality of successive data packets each including a string of digital data, said data representing either digitized voice signals or other types of digital signals, an 8 bit repeat byte (indicating whether said successive data packets are repeats of previously-transmitted packets) separating some of said data packets, and

(c) an end-of-message word signifying the end of a given message.

9. A transceiver as in claim 8 wherein said control means processes said 64 bit guard band by processing digital signals in substantially the following sequence:

(a) a 4 bit command code indicating a task to be performed,

(b) a 1 bit NP code (indicating if said plurality of successive data packets are not present in a given message),

(c) a 1 bit mid command execution control bit,

(d) an 8 bit sub-group source code SUBGS (indicating the transceiver generating said message),

(e) an 8 bit sub-group destination code SUBGD (indicating, in conjunction with said selective signalling signals, the intended recipient of said message),

(f) a 6 bit BPP code indicating the number M of bytes of digital data in each of said plurality of data packets,

(g) a 6 bit PPB code indicating the number N of said plurality of successive data packets,

(h) 14 additional bits of digital signals, and

(i) 16 bits of error checking signals.

10. A method for reliably and quickly exchanging data bursts of digital data packets over an RF communications channel between a data transmitter and a data receiver, said method comprising the steps of:

(a) transmitting a plurality N of discrete digital data packets from said transmitter to said receiver without transmitting identifications for each of said discrete packets;

(b) checking for correct receipt of all of said N packets at said data receiver;

(c) transmitting a binary coded N-bit map of digital data from said data receiver back to said data transmitter, said map identifying which of said N packets have not yet been correctly received by said data receiver without expressly identifying said incorrectly received packets;

(d) retransmitting said identified packets from said transmitter to said receiver; and

(e) repeating said steps (b)-(d) until all of said N packets have been correctly received by said data receiver.

11. A method as in claim 10 wherein said transmitting step (c) includes transmitting said N bits of said map in a sequence corresponding to the sequence said transmitting step (a) transmits said N packets, each of said N bits corresponding to one of said packets.

12. An arrangement for reliably and quickly exchanging data bursts of digital data packets over an RF communications channel between a data transmitter and a data receiver, said arrangement comprising:

means for transmitting a plurality N of discrete digital data packets from said transmitter to said receiver without transmitting identifications for each of said discrete packets;

means at said receiver for checking for correct receipt of all of said N packets; and

means connected to said checking means for transmitting a binary coded N-bit map of digital data from said data receiver back to said data transmitter, said map identifying which of said N packets have not yet been correctly received by said data receiver without expressly identifying said incorrectly received packets,

wherein said first-mentioned transmitting means is also for retransmitting plural versions of said identified packets from said transmitter to said receiver plural lines and said checking means is also for checking for correct receipt of at least one of said plural retransmitted versions of each of said retransmitted packets until all of said N packets have been correctly received at least once by said data receiver.

13. An arrangement as in claim 12 wherein said bit map transmitting means includes means for transmitting said N bits of said map in a sequence corresponding to the sequence said packet transmitting means transmits said N packets, the positions of said N bits corresponding to and associated with said N packets.

14. A method for exchanging of data bursts of digital data packets over an RF communications channel, comprising the steps of:

(a) transmitting a data burst from a source RF transceiver to a destination RF transceiver, said data burst comprising a number N of discrete digital data packets, N being greater than one;

(b) testing for correct receipt of said N digital data packets at said destination transceiver;

(c) in response to said testing step, transmitting an acknowledgement message from said destination transceiver to said source transceiver, said acknowledgement message identifying at least which of said N packets were incorrectly received; and

(d) in response to said acknowledgement message, transmitting a further data burst from said source transceiver to said destination transceiver, said burst comprising said number N of discrete digital data packets, including the step of repeating each of said incorrectly received data packets a sufficient number of times in sequence to provide N packets.

15. A method as in claim 14 wherein said transmitting step (c) comprises transmitting a binary coded bit map comprising N bits corresponding to said N packets, a one-to-one correspondence existing between said N bits of said bit map and said N packets in the last transmitted data burst.

16. A method for reliably and quickly exchanging bursts of digital data packets between a first site and a second site over an RF communications channel, said method comprising the steps of:

(a) transmitting a plurality N digital data packets from said first site to said second site;

(b) checking for the correct receipt of all N packets at said second site;

(c) transmitting a binary coded N-bit map of digital data from said second site back to said first site identifying which data packets were correctly received at said second site;

(d) retransmitting the data packets, if any, not correctly received at said second site from said first site to said second site in response to receipt of said map; and

(e) repeating said steps (b)-(d) until all N packets have been correctly received at said second site.